{"gene":"TPO","run_date":"2026-06-10T10:51:55","timeline":{"discoveries":[{"year":2023,"finding":"Cryo-EM structures of human thyroid peroxidase (TPO) extracellular domain were determined at 3.4–3.92 Å resolution, revealing TPO as a monomer with four domains: N-terminal domain, peroxidase domain (POD), complement control protein (CCP)-like domain, and EGF-like domain. A disulfide bond between Cys146 (POD) and Cys756 (CCP) fixes the relative domain positions. The haem group, calcium binding site, and enzyme active site entrance are on the opposite face from the autoantibody binding sites (POD domain).","method":"Cryo-electron microscopy with TPO complexed with Fab fragments (monoclonal autoantibody 2G4 and mouse monoclonal 4F5)","journal":"Journal of molecular endocrinology","confidence":"High","confidence_rationale":"Tier 1 / Strong — first high-resolution structure of TPO, determined by cryo-EM with two independent antibody complexes providing orthogonal structural validation","pmids":["36537574"],"is_preprint":false},{"year":1998,"finding":"TPO catalytic mechanism depends on distal histidine His239 and proximal histidine His494 (identified by sequence alignment with myeloperoxidase). Asn579, which likely forms a stabilizing hydrogen bond with the proximal histidine, is absent in the alternatively spliced form TPO-2, explaining the lack of enzymatic activity of TPO-2. Arg396 is proposed to be required for compound I formation by analogy with other peroxidases.","method":"Amino acid sequence alignment across mammalian and invertebrate peroxidases; functional inference from alternatively spliced variant lacking residues 533–589","journal":"Thyroid : official journal of the American Thyroid Association","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — sequence-based mechanistic inference across multiple species plus functional correlation with splice variant, single lab, no direct mutagenesis reported in abstract","pmids":["9510129"],"is_preprint":false},{"year":2010,"finding":"TPO is a heme-binding protein localized on the apical membrane of the thyrocyte; its enzymatic activity is essential for thyroid hormonogenesis (iodide organification). Inactivating mutations in TPO cause thyroid dyshormonogenesis and congenital hypothyroidism with a total iodide organification defect.","method":"Genetic/functional analysis of TPO mutations in congenital hypothyroidism patients; review of 61 annotated mutations","journal":"Molecular and cellular endocrinology","confidence":"High","confidence_rationale":"Tier 2 / Strong — replicated across many independent patient cohorts and functional studies; established enzymatic role in iodide organification is well-documented","pmids":["20153806"],"is_preprint":false},{"year":2020,"finding":"In vitro enzyme activity assays of TPO missense mutants demonstrated that residual TPO enzymatic activity correlates with clinical severity in congenital hypothyroidism: patients with <15% residual activity had severe CH (markedly elevated TSH, pronounced goiter, higher L-thyroxine requirement), while those with >16% residual activity had mild CH.","method":"In vitro enzymatic activity assay of TPO mutants expressed in cells; correlation with clinical phenotype in 230 Chinese CH patients","journal":"Molecular and cellular endocrinology","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct in vitro enzyme activity measurements with functional (clinical) validation across a large patient cohort","pmids":["32088313"],"is_preprint":false},{"year":2018,"finding":"Breast-expressed TPO has slightly lower molecular weight than thyroid TPO due to decreased glycosylation. Breast TPO exhibits enzymatic activity and isoelectric point comparable to thyroid TPO, but in mammary cell lines the majority of TPO is cytoplasmic and cell-surface expression is insufficient to detect enzymatic activity. No peroxidase activity or dimer formation was detected in breast-derived cell lines.","method":"Western blot, glycosylation analysis, peroxidase activity assay, isoelectric focusing, subcellular localization in breast tissue-derived cell lines","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal biochemical methods in a single study; finding about subcellular localization tied to lack of enzymatic activity at cell surface","pmids":["29513734"],"is_preprint":false},{"year":1995,"finding":"TPO (thrombopoietin) induces tyrosine phosphorylation and activation of STAT5 (major component of the DNA-binding complex) and STAT3 in hematopoietic cells via its receptor c-Mpl, defining a rapid JAK-STAT signaling pathway downstream of TPO.","method":"DNA-binding assays (EMSA), tyrosine phosphorylation assays, immunoprecipitation in hematopoietic cells stimulated with TPO","journal":"FEBS letters","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal biochemical methods (EMSA + phosphorylation assays), replicated in context of broader JAK2 activation findings","pmids":["7544303"],"is_preprint":false},{"year":2004,"finding":"The adaptor protein Lnk negatively regulates TPO/c-Mpl signaling. Lnk overexpression attenuates TPO-induced STAT3, STAT5, Akt, and MAPK signaling; Lnk deficiency causes enhanced and prolonged activation of these pathways in megakaryocytes. The SH2 domain of Lnk is essential for this inhibitory function; the PH domain contributes but is not essential; the conserved C-terminal tyrosine is dispensable.","method":"Overexpression and knockout mouse studies; phosphorylation assays for STAT3, STAT5, Akt, MAPK; domain-deletion mutant analysis; megakaryocyte colony assays","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic (Lnk-/- mice) plus domain-mutant biochemical dissection, multiple signaling readouts, replicated in primary cells and cell lines","pmids":["15337790"],"is_preprint":false},{"year":2001,"finding":"Upon TPO stimulation, adaptor proteins Gab1 and Gab2 are tyrosine-phosphorylated and associate with Shc, SHP2, PI3-kinase, and Grb2 in mpl-expressing cells. In primary human megakaryocytic progenitors, only Gab1 is expressed and phosphorylated. Y112 in the C-terminal cytoplasmic domain of c-Mpl is required for Gab1/2 phosphorylation and subsequent PI3K/Akt activation; a Y112 mutant mpl fails to activate PI3K and does not support cell proliferation.","method":"Co-immunoprecipitation, tyrosine phosphorylation assays, mpl mutant analysis in UT7 and primary cells","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 / Strong — receptor mutant (Y112) dissection combined with Co-IP in multiple cell systems including primary cells; PI3K pathway placement confirmed","pmids":["11402314"],"is_preprint":false},{"year":1995,"finding":"TPO (thrombopoietin) stimulation induces tyrosine phosphorylation of JAK2, Shc, and Vav in myeloid precursor cells. JAK1 phosphorylation is induced by IL-3 but NOT by TPO, distinguishing TPO and IL-3 signal transduction at a molecular level.","method":"Tyrosine phosphorylation assays and immunoprecipitation of JAK1, JAK2, Shc, Vav in myeloid precursor cells after TPO or IL-3 stimulation","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct biochemical identification of signaling substrates with negative control (JAK1 not phosphorylated by TPO), single lab","pmids":["7545904"],"is_preprint":false},{"year":2005,"finding":"TPO (thrombopoietin) induces c-myc expression in megakaryocytes through a PI3K- and MAPK-dependent pathway. This induction is not mediated by Akt, PKCζ, or mTOR, distinguishing the c-myc regulatory pathway from other PI3K downstream effectors.","method":"Quantitative real-time RT-PCR of c-myc; pharmacological inhibitors of PI3K, MAPK, Akt, PKCζ, mTOR; active Akt overexpression in UT-7 and BaF3/Mpl cells and primary murine megakaryocytes","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple pathway inhibitors used in parallel with genetic overexpression, single lab, consistent results across cell lines and primary cells","pmids":["16380230"],"is_preprint":false},{"year":2006,"finding":"In TPO-driven megakaryocyte differentiation, MEK inhibition (via PD98059) increased polyploidization, while mTOR inhibition (via rapamycin) strongly inhibited polyploidization. MEK inhibition caused nuclear localization of cyclin D3, whereas mTOR inhibition caused exclusively cytoplasmic cyclin D3 localization. This demonstrates that TPO-activated MEK/ERK and PI3K/AKT/mTOR pathways have opposing effects on megakaryocyte ploidy.","method":"Pharmacological inhibition (PD98059, rapamycin), Western blot for p-ERK and p70S6K, flow cytometry for DNA content, immunolocalization of cyclin D3 in human CD34+-derived megakaryocytes","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (phosphoprotein analysis, ploidy, localization), single lab, human primary cells","pmids":["16449323"],"is_preprint":false},{"year":2014,"finding":"JAK2 and MPL protein expression levels determine whether TPO induces megakaryocyte proliferation or differentiation: decreasing JAK2 or MPL expression (or JAK2 chemical inhibition) suppresses TPO-induced proliferation arrest and differentiation. Low doses of JAK2 inhibitors paradoxically increase MK production both in vitro and in vivo.","method":"siRNA knockdown of JAK2/MPL, JAK2 chemical inhibitors, in vitro megakaryocyte differentiation assays, in vivo mouse studies, Western blot for JAK2/MPL in patient samples","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockdown plus chemical inhibition plus in vivo validation, correlated with patient samples; multiple orthogonal methods","pmids":["25143485"],"is_preprint":false},{"year":2003,"finding":"Raf-1 is NOT required for megakaryocytopoiesis or TPO-induced ERK1/2 phosphorylation. raf-1-/- mice have normal to slightly elevated platelet counts, normal megakaryocyte expansion and ploidy, and normal TPO-induced ERK1/2 phosphorylation without compensatory upregulation of A-Raf or B-Raf.","method":"raf-1 knockout mice; platelet counts, megakaryocyte development assays, ERK1/2 phosphorylation assays, A-Raf/B-Raf expression analysis","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout with multiple cellular and biochemical readouts; clear negative mechanistic finding","pmids":["14576068"],"is_preprint":false},{"year":2003,"finding":"TPO (thrombopoietin) stimulates Hoxb4 expression 2–3-fold in primitive hematopoietic cell lines and HSCs via p38 MAPK, which induces upstream stimulating factor 1 (USF-1), a transcription factor that regulates Hoxb4. tpo-/- HSCs express 2–5-fold less Hoxb4 than controls, providing a molecular pathway for TPO's role in HSC self-renewal.","method":"Gene expression analysis in tpo-/- vs. wild-type HSC populations; p38 MAPK inhibitor studies; USF-1 induction assays in EML and UT-7/TPO cells","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — knockout mouse comparison combined with pharmacological pathway dissection, single lab, two orthogonal approaches","pmids":["12855555"],"is_preprint":false},{"year":1998,"finding":"TPO and c-Mpl knockout mice are viable but have ~90% reduction in platelet counts due to reduced megakaryocyte progenitor numbers and decreased megakaryocyte ploidy. The primary physiological role of TPO in vivo is to control the number, not the maturation, of megakaryocytes and platelets. TPO also affects hematopoietic stem cell repopulating capacity. Circulating TPO levels are regulated by the platelet mass through binding to c-Mpl receptors on platelets (feedback mechanism).","method":"Gene-targeted TPO and c-Mpl knockout mouse studies; platelet counts; BM repopulation assays; progenitor cell enumeration","journal":"Stem cells (Dayton, Ohio)","confidence":"High","confidence_rationale":"Tier 2 / Strong — dual genetic knockouts with multiple hematopoietic readouts; feedback mechanism established by receptor binding analysis on platelets","pmids":["9474742"],"is_preprint":false},{"year":1996,"finding":"TPO (thrombopoietin) induces tyrosine phosphorylation of JAK2 and STAT5-related protein in megakaryoblastic cells. The UT-7/TPO cell line established absolute TPO dependence for growth and survival, with TPO signaling through c-Mpl to activate JAK2/STAT5 pathway.","method":"Western blot for JAK2 and STAT5 tyrosine phosphorylation in UT-7/TPO cells; mpl mRNA detection by RT-PCR","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct biochemical demonstration of JAK2/STAT5 activation; single lab; consistent with parallel findings in the field","pmids":["8639823"],"is_preprint":false},{"year":2000,"finding":"Platelets release full-length biologically active TPO (thrombopoietin) upon activation with platelet agonists. Platelet fractionation indicates stored TPO is contained in granules. Pre-incubation with TPO peptide mimetic or truncated TPO increases TPO release 3–5-fold upon activation, suggesting competition with Mpl-bound TPO.","method":"Platelet stimulation assays, platelet fractionation experiments, biological activity assays, clinical correlation with DIC patients","journal":"Thrombosis and haemostasis","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — subcellular fractionation identifying granule storage plus functional release assay; single lab; clinical correlation provided","pmids":["10896250"],"is_preprint":false},{"year":1996,"finding":"TPO (thrombopoietin) stimulation leads to formation of a Grb2 complex containing JAK2 (via c-Mpl), distinct from SCF/c-Kit stimulation where Grb2 interacts with c-Kit through its SH2 domain. TPO-induced c-Cbl tyrosine phosphorylation occurs via JAK2 (non-tyrosine kinase receptor pathway) rather than direct receptor interaction.","method":"Co-immunoprecipitation, in vitro binding assays, tyrosine phosphorylation assays in M-07e cells stimulated with TPO or SCF","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with in vitro confirmation; single lab; direct comparison between two receptor systems","pmids":["8950973"],"is_preprint":false},{"year":2015,"finding":"TPO (thrombopoietin) promotes liver metastasis of CD110+ colorectal cancer tumor-initiating cells by activating lysine degradation, generating acetyl-CoA (used for p300-dependent LRP6 acetylation triggering Wnt signaling for self-renewal) and glutamate (modulating redox status for drug resistance). TPO-mediated c-myc induction orchestrates chromatin modifier recruitment to regulate metabolic gene expression.","method":"Metabolic profiling, acetylation assays, Wnt signaling assays, redox assays, c-myc loss-of-function in CD110+ TICs; in vivo liver metastasis models","journal":"Cell stem cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple metabolic and signaling assays in vitro and in vivo; single lab; mechanistic pathway established by pharmacological and genetic interventions","pmids":["26140605"],"is_preprint":false},{"year":2020,"finding":"Both TPO (thrombopoietin) and its receptor c-Mpl are expressed in neurons of the human CNS. TPO is neuroprotective in hypoxic-ischemic neonatal rat brain models, reducing brain damage. TPO promotes C17.2 cell proliferation through PI3K/Akt signaling and exerts anti-apoptotic effects via the Bcl-2/BAX pathway by suppressing mitochondrial membrane potential loss.","method":"Immunohistochemistry of human CNS tissue; neonatal rat hypoxic-ischemic model; Western blot for PI3K/Akt and Bcl-2/BAX pathway components; proliferation and apoptosis assays","journal":"Aging","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo animal model with mechanistic pathway dissection; single lab; two orthogonal signaling readouts","pmids":["32341206"],"is_preprint":false},{"year":2006,"finding":"TPO (thrombopoietin) regulates PDGF-B, PDGFRα, and PDGFRβ expression in UT-7/TPO megakaryocytic cells, induces tyrosine phosphorylation of PDGFRα (but not PDGFRβ), and promotes PDGFRαβ heterodimer formation. During megakaryocytic differentiation, PDGFRs form complexes with neuropilin-1 (NRP-1), suggesting NRP-1 involvement in megakaryopoiesis.","method":"Western blot, co-immunoprecipitation, immunocytochemistry, tyrosine phosphorylation assays in UT-7/TPO cells","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP and immunocytochemistry confirming complex formation; single lab; multiple orthogonal methods","pmids":["25744030"],"is_preprint":false},{"year":2018,"finding":"TPO expression in thyroid cells is downregulated via a p38/TRHr-dependent pathway: triclosan activates p38, which induces TRHr expression; inhibition of p38 suppresses TRHr induction and restores TPO expression. TRHr siRNA knockdown also suppresses TPO.","method":"Rat in vivo triclosan treatment; Nthy-ori 3-1 cell culture with p38 inhibitors and TRHr siRNA; Western blot and RT-PCR for TPO expression","journal":"Cellular physiology and biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic (siRNA) and pharmacological pathway dissection in vitro and in vivo; single lab","pmids":["29462796"],"is_preprint":false},{"year":2006,"finding":"IL-1α/IFN-γ (Th1 cytokines) downregulate TPO protein and mRNA expression in human thyrocytes in a nitric oxide (NO)-dependent manner; this effect is partially prevented by the NOS inhibitor L-NAME, establishing NO as a mediator of Th1 cytokine-induced TPO suppression.","method":"Cytokine treatment of isolated human thyrocytes; L-NAME (NOS inhibitor) co-incubation; Western blot and RT-PCR for TPO and ThOXs; NO release measurement","journal":"American journal of physiology. Endocrinology and metabolism","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacological pathway dissection with enzyme inhibitor showing partial rescue; single lab; human primary thyrocytes","pmids":["16478776"],"is_preprint":false},{"year":2002,"finding":"PLZF activates TPO receptor (TpoR/c-Mpl) transcription in megakaryocytic cells by binding to a PLZF recognition site in the proximal TpoR promoter. PLZF and GATA1 proteins co-immunoprecipitate in PLZF-expressing cells, and their co-expression potentiates megakaryocytic marker upregulation, suggesting a PLZF/GATA1 transcriptional complex regulates TpoR expression.","method":"Promoter deletion constructs, co-immunoprecipitation of PLZF and GATA1, retroviral transduction of TF1 cells, flow cytometry for megakaryocytic markers","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — promoter deletion mapping plus Co-IP of transcription factor complex; single lab; two orthogonal approaches","pmids":["12242665"],"is_preprint":false}],"current_model":"TPO (thyroid peroxidase) is a heme-containing enzyme localized on the apical membrane of thyrocytes that catalyzes iodide organification essential for thyroid hormone synthesis, with a structure now resolved by cryo-EM revealing four domains stabilized by a Cys146–Cys756 disulfide bond, a peroxidase active site requiring His239, His494, and Asn579, and an immunodominant region on the POD domain targeted by autoantibodies; separately, TPO (thrombopoietin) signals through its receptor c-Mpl to activate JAK2/STAT3/STAT5, PI3K/Akt/mTOR, and Ras/MAPK pathways, driving megakaryocyte proliferation, polyploidization, and platelet production, with pathway flux regulated by adaptor proteins (Lnk via its SH2 domain, Gab1/2 via c-Mpl Y112), and by the relative levels of JAK2 and MPL protein determining whether the outcome is proliferation or differentiation."},"narrative":{"mechanistic_narrative":"The TPO symbol in this corpus resolves to two molecularly distinct, internally coherent proteins, and the synthesis here treats them separately. Thyroid peroxidase is a heme-containing, calcium-binding enzyme on the apical membrane of thyrocytes that catalyzes iodide organification, the essential committed step of thyroid hormone synthesis [PMID:20153806]. Cryo-EM of its extracellular domain resolves a monomeric four-domain architecture (N-terminal, peroxidase/POD, CCP-like, and EGF-like domains) in which a Cys146–Cys756 disulfide locks domain orientation, and which positions the heme, calcium site, and active-site entrance on the face opposite the POD-domain autoantibody epitopes [PMID:36537574]. Catalysis depends on a distal His239 and a proximal His494, with Asn579 stabilizing the proximal histidine—loss of these residues in the alternatively spliced TPO-2 form abolishes activity [PMID:9510129]. Inactivating TPO mutations cause thyroid dyshormonogenesis and congenital hypothyroidism with a total iodide organification defect, and residual in vitro enzymatic activity quantitatively tracks clinical severity [PMID:20153806, PMID:32088313]. Separately, thrombopoietin is a hematopoietic cytokine that signals through the receptor c-Mpl to control megakaryocyte number, polyploidization, and platelet production, as well as hematopoietic stem cell self-renewal [PMID:9474742]. Ligand engagement activates JAK2 (but not JAK1) and the STAT5/STAT3, PI3K/Akt, and Ras/MAPK arms [PMID:7544303, PMID:7545904, PMID:8639823], with receptor tyrosine Y112 recruiting Gab1/Gab2 to drive PI3K/Akt and proliferation [PMID:11402314], and the adaptor Lnk acting through its SH2 domain as a negative regulator of these outputs [PMID:15337790]. The balance between proliferation and differentiation is set by the relative levels of JAK2 and MPL protein and by opposing MEK/ERK versus PI3K/Akt/mTOR control of ploidy [PMID:16449323, PMID:25143485].","teleology":[{"year":1995,"claim":"Establishing the immediate signaling output of thrombopoietin defined how c-Mpl engagement is transduced, showing it activates the JAK-STAT axis and selectively engages JAK2 rather than JAK1.","evidence":"EMSA, tyrosine phosphorylation and immunoprecipitation assays in hematopoietic and myeloid precursor cells, including a JAK1 negative control distinguishing TPO from IL-3","pmids":["7544303","7545904"],"confidence":"High","gaps":["Does not resolve which STAT outputs drive proliferation versus differentiation","Direct receptor residues coupling c-Mpl to JAK2 not mapped here"]},{"year":1996,"claim":"Identification of a TPO-dependent megakaryoblastic cell line and the Grb2/JAK2/c-Cbl complex clarified how the receptor nucleates downstream adaptors distinct from receptor tyrosine kinase signaling.","evidence":"JAK2/STAT5 phosphorylation in UT-7/TPO cells and Co-IP comparing TPO/c-Mpl versus SCF/c-Kit adaptor recruitment","pmids":["8639823","8950973"],"confidence":"Medium","gaps":["Functional consequence of the Grb2/JAK2 complex on cell fate not isolated","c-Cbl downstream role undefined"]},{"year":1998,"claim":"Genetic ablation of TPO and c-Mpl established the physiological role of the cytokine as a controller of megakaryocyte/platelet number and a regulator of HSC repopulation, with a platelet-mass feedback loop.","evidence":"TPO and c-Mpl knockout mice with platelet counts, progenitor enumeration, BM repopulation assays, and platelet receptor-binding analysis","pmids":["9474742"],"confidence":"High","gaps":["Molecular basis of HSC self-renewal effect not defined here","Does not explain ploidy control mechanism"]},{"year":1998,"claim":"Assigning the catalytic residues of thyroid peroxidase and correlating them with the inactive splice variant explained the structural requirements for peroxidase activity.","evidence":"Sequence alignment with myeloperoxidase identifying His239/His494/Asn579/Arg396 plus functional correlation with activity-null TPO-2 lacking residues 533–589","pmids":["9510129"],"confidence":"Medium","gaps":["No direct site-directed mutagenesis of individual residues reported","Compound I formation role of Arg396 inferred by analogy"]},{"year":2001,"claim":"Mapping c-Mpl Y112 to Gab1/Gab2 recruitment defined the receptor module that couples thrombopoietin to PI3K/Akt and proliferation.","evidence":"Co-IP of Gab1/2 with Shc/SHP2/PI3K/Grb2 and Y112 mutant c-Mpl analysis in UT7 and primary megakaryocytic progenitors","pmids":["11402314"],"confidence":"High","gaps":["Why only Gab1 is expressed in primary progenitors not explained","Quantitative contribution of PI3K versus other arms to proliferation not partitioned"]},{"year":2002,"claim":"Identifying PLZF/GATA1 control of the TpoR promoter showed how receptor expression itself is transcriptionally set during megakaryocytic commitment.","evidence":"Promoter deletion mapping and PLZF/GATA1 Co-IP in retrovirally transduced TF1 cells","pmids":["12242665"],"confidence":"Medium","gaps":["Direct DNA-binding stoichiometry of the PLZF/GATA1 complex not resolved","In vivo relevance to receptor levels not tested"]},{"year":2003,"claim":"Dissection of the MAPK branch separated essential from dispensable kinases, showing Raf-1 is not required while p38 links TPO to Hoxb4 via USF-1 for HSC self-renewal.","evidence":"raf-1 knockout mice with ERK readouts and p38-inhibitor/USF-1 induction analysis with tpo-/- HSC comparison","pmids":["14576068","12855555"],"confidence":"High","gaps":["Which Raf isoform substitutes for Raf-1 in ERK activation not identified","Magnitude of Hoxb4 change (2–5 fold) leaves quantitative contribution to self-renewal uncertain"]},{"year":2005,"claim":"Tracing c-myc induction to a PI3K/MAPK route independent of Akt/mTOR refined which downstream effectors control megakaryocyte transcriptional output.","evidence":"qRT-PCR of c-myc with PI3K/MAPK/Akt/PKCζ/mTOR inhibitors and active-Akt overexpression in UT-7, BaF3/Mpl, and primary megakaryocytes","pmids":["16380230"],"confidence":"Medium","gaps":["The PI3K effector bridging to c-myc independent of Akt not identified","Direct transcriptional mediator at the c-myc locus undefined"]},{"year":2006,"claim":"Defining opposing MEK/ERK and PI3K/AKT/mTOR effects on ploidy, with cyclin D3 localization as readout, established how a single ligand balances proliferation against polyploidization.","evidence":"PD98059 and rapamycin treatment with ploidy flow cytometry and cyclin D3 immunolocalization in human CD34+-derived megakaryocytes","pmids":["16449323"],"confidence":"Medium","gaps":["Mechanism linking mTOR to nuclear cyclin D3 retention not resolved","Single-lab pharmacology without genetic confirmation"]},{"year":2004,"claim":"Identifying Lnk as an SH2-dependent negative regulator placed a brake on the breadth of TPO signaling outputs.","evidence":"Lnk overexpression and knockout mice with STAT3/STAT5/Akt/MAPK phosphorylation, domain-deletion mutants, and megakaryocyte colony assays","pmids":["15337790"],"confidence":"High","gaps":["The phosphotyrosine docking site engaged by the Lnk SH2 domain not mapped","PH domain contribution mechanism unresolved"]},{"year":2010,"claim":"Consolidating TPO genetics fixed thyroid peroxidase as the enzyme whose loss causes a total iodide organification defect and congenital hypothyroidism.","evidence":"Functional/genetic analysis of TPO mutations across congenital hypothyroidism cohorts (review of 61 mutations)","pmids":["20153806"],"confidence":"High","gaps":["Per-residue structural consequences not yet linked to mechanism at this stage","Genotype-phenotype quantitation not established here"]},{"year":2014,"claim":"Showing that JAK2 and MPL protein levels dictate proliferation-versus-differentiation outcome revealed a dosage logic, including a paradoxical pro-megakaryocytic effect of low-dose JAK2 inhibition.","evidence":"siRNA knockdown of JAK2/MPL, JAK2 chemical inhibition, in vitro/in vivo differentiation assays, and patient-sample Western blots","pmids":["25143485"],"confidence":"High","gaps":["Quantitative thresholds of JAK2/MPL setting each fate not defined","How the same kinase output is interpreted as opposite fates remains unresolved"]},{"year":2015,"claim":"Demonstrating that thrombopoietin drives metabolic reprogramming in colorectal tumor-initiating cells extended its signaling into oncogenic self-renewal beyond hematopoiesis.","evidence":"Metabolic profiling, acetylation/Wnt/redox assays, c-myc loss-of-function in CD110+ TICs and in vivo liver metastasis models","pmids":["26140605"],"confidence":"Medium","gaps":["Generality across cancer types not established","Direct receptor coupling to lysine degradation enzymes not mapped"]},{"year":2018,"claim":"Identifying breast-expressed thyroid peroxidase and its predominantly cytoplasmic distribution showed enzymatic activity depends on apical/cell-surface presentation absent in mammary cells.","evidence":"Western blot, glycosylation analysis, isoelectric focusing, peroxidase activity assays, and subcellular localization in breast-derived cell lines","pmids":["29513734"],"confidence":"Medium","gaps":["Functional role of cytoplasmic breast TPO undefined","Trafficking defect mechanism not identified"]},{"year":2018,"claim":"Linking thyroid TPO downregulation to a p38/TRHr pathway revealed an environmental-chemical route by which TPO expression is suppressed.","evidence":"Rat triclosan exposure with Nthy-ori 3-1 p38 inhibitor and TRHr siRNA experiments measuring TPO expression","pmids":["29462796"],"confidence":"Medium","gaps":["Direct transcriptional mechanism downstream of TRHr on the TPO gene not defined","Generalizability beyond triclosan unknown"]},{"year":2020,"claim":"Showing thrombopoietin and c-Mpl expression in CNS neurons with PI3K/Akt-mediated neuroprotection extended the cytokine's anti-apoptotic signaling to a non-hematopoietic tissue.","evidence":"Human CNS immunohistochemistry, neonatal rat hypoxic-ischemic model, and PI3K/Akt and Bcl-2/BAX pathway analysis with proliferation/apoptosis assays","pmids":["32341206"],"confidence":"Medium","gaps":["Physiological role of neuronal TPO under non-injury conditions unknown","Single-lab finding without independent confirmation"]},{"year":2023,"claim":"The first high-resolution structure of thyroid peroxidase resolved its domain architecture, the disulfide stabilizing it, and the spatial separation of catalytic site from autoantibody epitopes.","evidence":"Cryo-EM of the TPO extracellular domain at 3.4–3.92 Å complexed with two independent Fab fragments","pmids":["36537574"],"confidence":"High","gaps":["Membrane-anchored full-length conformation not resolved","Catalytic cycle intermediates not captured structurally"]},{"year":null,"claim":"It remains unresolved how the same intracellular kinase modules are quantitatively interpreted to produce opposite megakaryocyte fates, and whether the non-hematopoietic thrombopoietin roles (CNS, tumor metabolism) operate through the canonical c-Mpl module.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified quantitative model linking JAK2/MPL dosage to fate","Receptor coupling for metabolic and neuroprotective effects not mapped","Structural basis of thyroid TPO catalysis at the membrane unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016491","term_label":"oxidoreductase activity","supporting_discovery_ids":[0,1,2,3]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[5,7,8,15]},{"term_id":"GO:0048018","term_label":"receptor ligand activity","supporting_discovery_ids":[5,14]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[5,7,14]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,2]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[4]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[16]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[5,7,8,11]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[2,3]},{"term_id":"R-HSA-109582","term_label":"Hemostasis","supporting_discovery_ids":[14,16]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[11,14,13]}],"complexes":[],"partners":["MPL","JAK2","STAT5","STAT3","GAB1","GAB2","GRB2","LNK"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P07202","full_name":"Thyroid 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expression in malignant tissue and cell lines derived from breast, lung, and ovarian tumors.","date":"2012","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/22967017","citation_count":19,"is_preprint":false},{"pmid":"28575127","id":"PMC_28575127","title":"Thyroid peroxidase (TPO) expressed in thyroid and breast tissues shows similar antigenic properties.","date":"2017","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/28575127","citation_count":18,"is_preprint":false},{"pmid":"29513734","id":"PMC_29513734","title":"Biochemical properties of thyroid peroxidase (TPO) expressed in human breast and mammary-derived cell lines.","date":"2018","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/29513734","citation_count":18,"is_preprint":false},{"pmid":"29296963","id":"PMC_29296963","title":"Novel TPO receptor agonist TA-316 contributes to platelet biogenesis from human iPS cells.","date":"2017","source":"Blood advances","url":"https://pubmed.ncbi.nlm.nih.gov/29296963","citation_count":18,"is_preprint":false},{"pmid":"11986210","id":"PMC_11986210","title":"Lineage-specific growth factors can compensate for stem and progenitor cell deficiencies at the postprogenitor cell level: an analysis of doubly TPO- and G-CSF receptor-deficient mice.","date":"2002","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/11986210","citation_count":18,"is_preprint":false},{"pmid":"11593644","id":"PMC_11593644","title":"Expression of ICAM-1, B7.1 and TPO on human thyrocytes induced by IFN-alpha.","date":"1999","source":"Chinese medical journal","url":"https://pubmed.ncbi.nlm.nih.gov/11593644","citation_count":17,"is_preprint":false},{"pmid":"10960526","id":"PMC_10960526","title":"Thrombopoietin and the TPO receptorduring platelet storage.","date":"2000","source":"Transfusion","url":"https://pubmed.ncbi.nlm.nih.gov/10960526","citation_count":17,"is_preprint":false},{"pmid":"35612671","id":"PMC_35612671","title":"The return of RET GateKeeper mutations? an in-silico exploratory analysis of potential resistance mechanisms to novel RET macrocyclic inhibitor TPX-0046.","date":"2022","source":"Investigational new drugs","url":"https://pubmed.ncbi.nlm.nih.gov/35612671","citation_count":16,"is_preprint":false},{"pmid":"11012185","id":"PMC_11012185","title":"The efficacy of recombinant TPO in murine And nonhuman primate models for myelosuppression and stem cell transplantation.","date":"1998","source":"Stem cells (Dayton, Ohio)","url":"https://pubmed.ncbi.nlm.nih.gov/11012185","citation_count":16,"is_preprint":false},{"pmid":"9574554","id":"PMC_9574554","title":"Thrombopoietin (TPO) knockout phenotype induced by cross-reactive antibodies against TPO following injection of mice with recombinant adenovirus encoding human TPO.","date":"1998","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/9574554","citation_count":14,"is_preprint":false},{"pmid":"27797414","id":"PMC_27797414","title":"TPO-RAs in pITP: description of a case series and analysis of predictive factors for response.","date":"2016","source":"European journal of haematology","url":"https://pubmed.ncbi.nlm.nih.gov/27797414","citation_count":14,"is_preprint":false},{"pmid":"32341206","id":"PMC_32341206","title":"c-Mpl and TPO expression in the human central nervous system neurons inhibits neuronal apoptosis.","date":"2020","source":"Aging","url":"https://pubmed.ncbi.nlm.nih.gov/32341206","citation_count":13,"is_preprint":false},{"pmid":"32078117","id":"PMC_32078117","title":"Mild TPO deficiency characterized by progressive goiter and normal serum TSH level.","date":"2020","source":"Endocrine","url":"https://pubmed.ncbi.nlm.nih.gov/32078117","citation_count":13,"is_preprint":false},{"pmid":"37407700","id":"PMC_37407700","title":"TPO as an indicator of lymph node metastasis and recurrence in papillary thyroid carcinoma.","date":"2023","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/37407700","citation_count":13,"is_preprint":false},{"pmid":"37907956","id":"PMC_37907956","title":"The association of Treg and Th17 cells development factors and anti-TPO autoantibodies in patients with recurrent pregnancy loss.","date":"2023","source":"BMC research notes","url":"https://pubmed.ncbi.nlm.nih.gov/37907956","citation_count":13,"is_preprint":false},{"pmid":"33010232","id":"PMC_33010232","title":"Augmentation of NK Cell Proliferation and Anti-tumor Immunity by Transgenic Expression of Receptors for EPO or TPO.","date":"2020","source":"Molecular therapy : the journal of the American Society of Gene Therapy","url":"https://pubmed.ncbi.nlm.nih.gov/33010232","citation_count":13,"is_preprint":false},{"pmid":"28500830","id":"PMC_28500830","title":"Association between TPO Asn698Thr and Thr725Pro gene polymorphisms and serum anti-TPO levels in Iranian patients with subclinical hypothyroidism.","date":"2017","source":"Hormones (Athens, Greece)","url":"https://pubmed.ncbi.nlm.nih.gov/28500830","citation_count":13,"is_preprint":false},{"pmid":"9510129","id":"PMC_9510129","title":"Proximal and distal histidines in thyroid peroxidase: relation to the alternatively spliced form, TPO-2.","date":"1998","source":"Thyroid : official journal of the American Thyroid Association","url":"https://pubmed.ncbi.nlm.nih.gov/9510129","citation_count":13,"is_preprint":false},{"pmid":"31585887","id":"PMC_31585887","title":"Homology between TSH-R/Tg/TPO and Hashimoto's encephalopathy autoantigens.","date":"2020","source":"Frontiers in bioscience (Landmark edition)","url":"https://pubmed.ncbi.nlm.nih.gov/31585887","citation_count":12,"is_preprint":false},{"pmid":"37557083","id":"PMC_37557083","title":"Anti-TPO IgG/Total IgE Ratio: Biomarker for Omalizumab Response Prediction in Chronic Spontaneous Urticaria.","date":"2023","source":"International archives of allergy and immunology","url":"https://pubmed.ncbi.nlm.nih.gov/37557083","citation_count":12,"is_preprint":false},{"pmid":"25744030","id":"PMC_25744030","title":"Platelet-derived growth factor receptors form complexes with neuropilin-1 during megakaryocytic differentiation of thrombopoietin-dependent UT-7/TPO cells.","date":"2015","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/25744030","citation_count":12,"is_preprint":false},{"pmid":"36537574","id":"PMC_36537574","title":"Cryo-electron microscopy structures of human thyroid peroxidase (TPO) in complex with TPO antibodies.","date":"2023","source":"Journal of molecular endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/36537574","citation_count":11,"is_preprint":false},{"pmid":"28067429","id":"PMC_28067429","title":"Lnk Deficiency Leads to TPO-Mediated Osteoclastogenesis and Increased Bone Mass Phenotype.","date":"2017","source":"Journal of cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/28067429","citation_count":11,"is_preprint":false},{"pmid":"26174974","id":"PMC_26174974","title":"Novel genetic variants in the TPO gene cause congenital hypothyroidism.","date":"2015","source":"Scandinavian journal of clinical and laboratory investigation","url":"https://pubmed.ncbi.nlm.nih.gov/26174974","citation_count":11,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":54329,"output_tokens":6444,"usd":0.129824,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":15369,"output_tokens":5551,"usd":0.10781,"stage2_stop_reason":"end_turn"},"total_usd":0.237634,"stage1_batch_id":"msgbatch_017qqVz33Ga63SCDwzb35XPb","stage2_batch_id":"msgbatch_01Scr2Ei9x4HJMiRGxwrmvLK","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2023,\n      \"finding\": \"Cryo-EM structures of human thyroid peroxidase (TPO) extracellular domain were determined at 3.4–3.92 Å resolution, revealing TPO as a monomer with four domains: N-terminal domain, peroxidase domain (POD), complement control protein (CCP)-like domain, and EGF-like domain. A disulfide bond between Cys146 (POD) and Cys756 (CCP) fixes the relative domain positions. The haem group, calcium binding site, and enzyme active site entrance are on the opposite face from the autoantibody binding sites (POD domain).\",\n      \"method\": \"Cryo-electron microscopy with TPO complexed with Fab fragments (monoclonal autoantibody 2G4 and mouse monoclonal 4F5)\",\n      \"journal\": \"Journal of molecular endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — first high-resolution structure of TPO, determined by cryo-EM with two independent antibody complexes providing orthogonal structural validation\",\n      \"pmids\": [\"36537574\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"TPO catalytic mechanism depends on distal histidine His239 and proximal histidine His494 (identified by sequence alignment with myeloperoxidase). Asn579, which likely forms a stabilizing hydrogen bond with the proximal histidine, is absent in the alternatively spliced form TPO-2, explaining the lack of enzymatic activity of TPO-2. Arg396 is proposed to be required for compound I formation by analogy with other peroxidases.\",\n      \"method\": \"Amino acid sequence alignment across mammalian and invertebrate peroxidases; functional inference from alternatively spliced variant lacking residues 533–589\",\n      \"journal\": \"Thyroid : official journal of the American Thyroid Association\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — sequence-based mechanistic inference across multiple species plus functional correlation with splice variant, single lab, no direct mutagenesis reported in abstract\",\n      \"pmids\": [\"9510129\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"TPO is a heme-binding protein localized on the apical membrane of the thyrocyte; its enzymatic activity is essential for thyroid hormonogenesis (iodide organification). Inactivating mutations in TPO cause thyroid dyshormonogenesis and congenital hypothyroidism with a total iodide organification defect.\",\n      \"method\": \"Genetic/functional analysis of TPO mutations in congenital hypothyroidism patients; review of 61 annotated mutations\",\n      \"journal\": \"Molecular and cellular endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — replicated across many independent patient cohorts and functional studies; established enzymatic role in iodide organification is well-documented\",\n      \"pmids\": [\"20153806\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In vitro enzyme activity assays of TPO missense mutants demonstrated that residual TPO enzymatic activity correlates with clinical severity in congenital hypothyroidism: patients with <15% residual activity had severe CH (markedly elevated TSH, pronounced goiter, higher L-thyroxine requirement), while those with >16% residual activity had mild CH.\",\n      \"method\": \"In vitro enzymatic activity assay of TPO mutants expressed in cells; correlation with clinical phenotype in 230 Chinese CH patients\",\n      \"journal\": \"Molecular and cellular endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct in vitro enzyme activity measurements with functional (clinical) validation across a large patient cohort\",\n      \"pmids\": [\"32088313\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Breast-expressed TPO has slightly lower molecular weight than thyroid TPO due to decreased glycosylation. Breast TPO exhibits enzymatic activity and isoelectric point comparable to thyroid TPO, but in mammary cell lines the majority of TPO is cytoplasmic and cell-surface expression is insufficient to detect enzymatic activity. No peroxidase activity or dimer formation was detected in breast-derived cell lines.\",\n      \"method\": \"Western blot, glycosylation analysis, peroxidase activity assay, isoelectric focusing, subcellular localization in breast tissue-derived cell lines\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal biochemical methods in a single study; finding about subcellular localization tied to lack of enzymatic activity at cell surface\",\n      \"pmids\": [\"29513734\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"TPO (thrombopoietin) induces tyrosine phosphorylation and activation of STAT5 (major component of the DNA-binding complex) and STAT3 in hematopoietic cells via its receptor c-Mpl, defining a rapid JAK-STAT signaling pathway downstream of TPO.\",\n      \"method\": \"DNA-binding assays (EMSA), tyrosine phosphorylation assays, immunoprecipitation in hematopoietic cells stimulated with TPO\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal biochemical methods (EMSA + phosphorylation assays), replicated in context of broader JAK2 activation findings\",\n      \"pmids\": [\"7544303\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"The adaptor protein Lnk negatively regulates TPO/c-Mpl signaling. Lnk overexpression attenuates TPO-induced STAT3, STAT5, Akt, and MAPK signaling; Lnk deficiency causes enhanced and prolonged activation of these pathways in megakaryocytes. The SH2 domain of Lnk is essential for this inhibitory function; the PH domain contributes but is not essential; the conserved C-terminal tyrosine is dispensable.\",\n      \"method\": \"Overexpression and knockout mouse studies; phosphorylation assays for STAT3, STAT5, Akt, MAPK; domain-deletion mutant analysis; megakaryocyte colony assays\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic (Lnk-/- mice) plus domain-mutant biochemical dissection, multiple signaling readouts, replicated in primary cells and cell lines\",\n      \"pmids\": [\"15337790\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Upon TPO stimulation, adaptor proteins Gab1 and Gab2 are tyrosine-phosphorylated and associate with Shc, SHP2, PI3-kinase, and Grb2 in mpl-expressing cells. In primary human megakaryocytic progenitors, only Gab1 is expressed and phosphorylated. Y112 in the C-terminal cytoplasmic domain of c-Mpl is required for Gab1/2 phosphorylation and subsequent PI3K/Akt activation; a Y112 mutant mpl fails to activate PI3K and does not support cell proliferation.\",\n      \"method\": \"Co-immunoprecipitation, tyrosine phosphorylation assays, mpl mutant analysis in UT7 and primary cells\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — receptor mutant (Y112) dissection combined with Co-IP in multiple cell systems including primary cells; PI3K pathway placement confirmed\",\n      \"pmids\": [\"11402314\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"TPO (thrombopoietin) stimulation induces tyrosine phosphorylation of JAK2, Shc, and Vav in myeloid precursor cells. JAK1 phosphorylation is induced by IL-3 but NOT by TPO, distinguishing TPO and IL-3 signal transduction at a molecular level.\",\n      \"method\": \"Tyrosine phosphorylation assays and immunoprecipitation of JAK1, JAK2, Shc, Vav in myeloid precursor cells after TPO or IL-3 stimulation\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct biochemical identification of signaling substrates with negative control (JAK1 not phosphorylated by TPO), single lab\",\n      \"pmids\": [\"7545904\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"TPO (thrombopoietin) induces c-myc expression in megakaryocytes through a PI3K- and MAPK-dependent pathway. This induction is not mediated by Akt, PKCζ, or mTOR, distinguishing the c-myc regulatory pathway from other PI3K downstream effectors.\",\n      \"method\": \"Quantitative real-time RT-PCR of c-myc; pharmacological inhibitors of PI3K, MAPK, Akt, PKCζ, mTOR; active Akt overexpression in UT-7 and BaF3/Mpl cells and primary murine megakaryocytes\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple pathway inhibitors used in parallel with genetic overexpression, single lab, consistent results across cell lines and primary cells\",\n      \"pmids\": [\"16380230\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"In TPO-driven megakaryocyte differentiation, MEK inhibition (via PD98059) increased polyploidization, while mTOR inhibition (via rapamycin) strongly inhibited polyploidization. MEK inhibition caused nuclear localization of cyclin D3, whereas mTOR inhibition caused exclusively cytoplasmic cyclin D3 localization. This demonstrates that TPO-activated MEK/ERK and PI3K/AKT/mTOR pathways have opposing effects on megakaryocyte ploidy.\",\n      \"method\": \"Pharmacological inhibition (PD98059, rapamycin), Western blot for p-ERK and p70S6K, flow cytometry for DNA content, immunolocalization of cyclin D3 in human CD34+-derived megakaryocytes\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (phosphoprotein analysis, ploidy, localization), single lab, human primary cells\",\n      \"pmids\": [\"16449323\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"JAK2 and MPL protein expression levels determine whether TPO induces megakaryocyte proliferation or differentiation: decreasing JAK2 or MPL expression (or JAK2 chemical inhibition) suppresses TPO-induced proliferation arrest and differentiation. Low doses of JAK2 inhibitors paradoxically increase MK production both in vitro and in vivo.\",\n      \"method\": \"siRNA knockdown of JAK2/MPL, JAK2 chemical inhibitors, in vitro megakaryocyte differentiation assays, in vivo mouse studies, Western blot for JAK2/MPL in patient samples\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockdown plus chemical inhibition plus in vivo validation, correlated with patient samples; multiple orthogonal methods\",\n      \"pmids\": [\"25143485\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Raf-1 is NOT required for megakaryocytopoiesis or TPO-induced ERK1/2 phosphorylation. raf-1-/- mice have normal to slightly elevated platelet counts, normal megakaryocyte expansion and ploidy, and normal TPO-induced ERK1/2 phosphorylation without compensatory upregulation of A-Raf or B-Raf.\",\n      \"method\": \"raf-1 knockout mice; platelet counts, megakaryocyte development assays, ERK1/2 phosphorylation assays, A-Raf/B-Raf expression analysis\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout with multiple cellular and biochemical readouts; clear negative mechanistic finding\",\n      \"pmids\": [\"14576068\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"TPO (thrombopoietin) stimulates Hoxb4 expression 2–3-fold in primitive hematopoietic cell lines and HSCs via p38 MAPK, which induces upstream stimulating factor 1 (USF-1), a transcription factor that regulates Hoxb4. tpo-/- HSCs express 2–5-fold less Hoxb4 than controls, providing a molecular pathway for TPO's role in HSC self-renewal.\",\n      \"method\": \"Gene expression analysis in tpo-/- vs. wild-type HSC populations; p38 MAPK inhibitor studies; USF-1 induction assays in EML and UT-7/TPO cells\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — knockout mouse comparison combined with pharmacological pathway dissection, single lab, two orthogonal approaches\",\n      \"pmids\": [\"12855555\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"TPO and c-Mpl knockout mice are viable but have ~90% reduction in platelet counts due to reduced megakaryocyte progenitor numbers and decreased megakaryocyte ploidy. The primary physiological role of TPO in vivo is to control the number, not the maturation, of megakaryocytes and platelets. TPO also affects hematopoietic stem cell repopulating capacity. Circulating TPO levels are regulated by the platelet mass through binding to c-Mpl receptors on platelets (feedback mechanism).\",\n      \"method\": \"Gene-targeted TPO and c-Mpl knockout mouse studies; platelet counts; BM repopulation assays; progenitor cell enumeration\",\n      \"journal\": \"Stem cells (Dayton, Ohio)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — dual genetic knockouts with multiple hematopoietic readouts; feedback mechanism established by receptor binding analysis on platelets\",\n      \"pmids\": [\"9474742\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"TPO (thrombopoietin) induces tyrosine phosphorylation of JAK2 and STAT5-related protein in megakaryoblastic cells. The UT-7/TPO cell line established absolute TPO dependence for growth and survival, with TPO signaling through c-Mpl to activate JAK2/STAT5 pathway.\",\n      \"method\": \"Western blot for JAK2 and STAT5 tyrosine phosphorylation in UT-7/TPO cells; mpl mRNA detection by RT-PCR\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct biochemical demonstration of JAK2/STAT5 activation; single lab; consistent with parallel findings in the field\",\n      \"pmids\": [\"8639823\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Platelets release full-length biologically active TPO (thrombopoietin) upon activation with platelet agonists. Platelet fractionation indicates stored TPO is contained in granules. Pre-incubation with TPO peptide mimetic or truncated TPO increases TPO release 3–5-fold upon activation, suggesting competition with Mpl-bound TPO.\",\n      \"method\": \"Platelet stimulation assays, platelet fractionation experiments, biological activity assays, clinical correlation with DIC patients\",\n      \"journal\": \"Thrombosis and haemostasis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — subcellular fractionation identifying granule storage plus functional release assay; single lab; clinical correlation provided\",\n      \"pmids\": [\"10896250\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"TPO (thrombopoietin) stimulation leads to formation of a Grb2 complex containing JAK2 (via c-Mpl), distinct from SCF/c-Kit stimulation where Grb2 interacts with c-Kit through its SH2 domain. TPO-induced c-Cbl tyrosine phosphorylation occurs via JAK2 (non-tyrosine kinase receptor pathway) rather than direct receptor interaction.\",\n      \"method\": \"Co-immunoprecipitation, in vitro binding assays, tyrosine phosphorylation assays in M-07e cells stimulated with TPO or SCF\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with in vitro confirmation; single lab; direct comparison between two receptor systems\",\n      \"pmids\": [\"8950973\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"TPO (thrombopoietin) promotes liver metastasis of CD110+ colorectal cancer tumor-initiating cells by activating lysine degradation, generating acetyl-CoA (used for p300-dependent LRP6 acetylation triggering Wnt signaling for self-renewal) and glutamate (modulating redox status for drug resistance). TPO-mediated c-myc induction orchestrates chromatin modifier recruitment to regulate metabolic gene expression.\",\n      \"method\": \"Metabolic profiling, acetylation assays, Wnt signaling assays, redox assays, c-myc loss-of-function in CD110+ TICs; in vivo liver metastasis models\",\n      \"journal\": \"Cell stem cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple metabolic and signaling assays in vitro and in vivo; single lab; mechanistic pathway established by pharmacological and genetic interventions\",\n      \"pmids\": [\"26140605\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Both TPO (thrombopoietin) and its receptor c-Mpl are expressed in neurons of the human CNS. TPO is neuroprotective in hypoxic-ischemic neonatal rat brain models, reducing brain damage. TPO promotes C17.2 cell proliferation through PI3K/Akt signaling and exerts anti-apoptotic effects via the Bcl-2/BAX pathway by suppressing mitochondrial membrane potential loss.\",\n      \"method\": \"Immunohistochemistry of human CNS tissue; neonatal rat hypoxic-ischemic model; Western blot for PI3K/Akt and Bcl-2/BAX pathway components; proliferation and apoptosis assays\",\n      \"journal\": \"Aging\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo animal model with mechanistic pathway dissection; single lab; two orthogonal signaling readouts\",\n      \"pmids\": [\"32341206\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"TPO (thrombopoietin) regulates PDGF-B, PDGFRα, and PDGFRβ expression in UT-7/TPO megakaryocytic cells, induces tyrosine phosphorylation of PDGFRα (but not PDGFRβ), and promotes PDGFRαβ heterodimer formation. During megakaryocytic differentiation, PDGFRs form complexes with neuropilin-1 (NRP-1), suggesting NRP-1 involvement in megakaryopoiesis.\",\n      \"method\": \"Western blot, co-immunoprecipitation, immunocytochemistry, tyrosine phosphorylation assays in UT-7/TPO cells\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP and immunocytochemistry confirming complex formation; single lab; multiple orthogonal methods\",\n      \"pmids\": [\"25744030\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"TPO expression in thyroid cells is downregulated via a p38/TRHr-dependent pathway: triclosan activates p38, which induces TRHr expression; inhibition of p38 suppresses TRHr induction and restores TPO expression. TRHr siRNA knockdown also suppresses TPO.\",\n      \"method\": \"Rat in vivo triclosan treatment; Nthy-ori 3-1 cell culture with p38 inhibitors and TRHr siRNA; Western blot and RT-PCR for TPO expression\",\n      \"journal\": \"Cellular physiology and biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic (siRNA) and pharmacological pathway dissection in vitro and in vivo; single lab\",\n      \"pmids\": [\"29462796\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"IL-1α/IFN-γ (Th1 cytokines) downregulate TPO protein and mRNA expression in human thyrocytes in a nitric oxide (NO)-dependent manner; this effect is partially prevented by the NOS inhibitor L-NAME, establishing NO as a mediator of Th1 cytokine-induced TPO suppression.\",\n      \"method\": \"Cytokine treatment of isolated human thyrocytes; L-NAME (NOS inhibitor) co-incubation; Western blot and RT-PCR for TPO and ThOXs; NO release measurement\",\n      \"journal\": \"American journal of physiology. Endocrinology and metabolism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological pathway dissection with enzyme inhibitor showing partial rescue; single lab; human primary thyrocytes\",\n      \"pmids\": [\"16478776\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"PLZF activates TPO receptor (TpoR/c-Mpl) transcription in megakaryocytic cells by binding to a PLZF recognition site in the proximal TpoR promoter. PLZF and GATA1 proteins co-immunoprecipitate in PLZF-expressing cells, and their co-expression potentiates megakaryocytic marker upregulation, suggesting a PLZF/GATA1 transcriptional complex regulates TpoR expression.\",\n      \"method\": \"Promoter deletion constructs, co-immunoprecipitation of PLZF and GATA1, retroviral transduction of TF1 cells, flow cytometry for megakaryocytic markers\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — promoter deletion mapping plus Co-IP of transcription factor complex; single lab; two orthogonal approaches\",\n      \"pmids\": [\"12242665\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TPO (thyroid peroxidase) is a heme-containing enzyme localized on the apical membrane of thyrocytes that catalyzes iodide organification essential for thyroid hormone synthesis, with a structure now resolved by cryo-EM revealing four domains stabilized by a Cys146–Cys756 disulfide bond, a peroxidase active site requiring His239, His494, and Asn579, and an immunodominant region on the POD domain targeted by autoantibodies; separately, TPO (thrombopoietin) signals through its receptor c-Mpl to activate JAK2/STAT3/STAT5, PI3K/Akt/mTOR, and Ras/MAPK pathways, driving megakaryocyte proliferation, polyploidization, and platelet production, with pathway flux regulated by adaptor proteins (Lnk via its SH2 domain, Gab1/2 via c-Mpl Y112), and by the relative levels of JAK2 and MPL protein determining whether the outcome is proliferation or differentiation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"The TPO symbol in this corpus resolves to two molecularly distinct, internally coherent proteins, and the synthesis here treats them separately. Thyroid peroxidase is a heme-containing, calcium-binding enzyme on the apical membrane of thyrocytes that catalyzes iodide organification, the essential committed step of thyroid hormone synthesis [#2]. Cryo-EM of its extracellular domain resolves a monomeric four-domain architecture (N-terminal, peroxidase/POD, CCP-like, and EGF-like domains) in which a Cys146–Cys756 disulfide locks domain orientation, and which positions the heme, calcium site, and active-site entrance on the face opposite the POD-domain autoantibody epitopes [#0]. Catalysis depends on a distal His239 and a proximal His494, with Asn579 stabilizing the proximal histidine—loss of these residues in the alternatively spliced TPO-2 form abolishes activity [#1]. Inactivating TPO mutations cause thyroid dyshormonogenesis and congenital hypothyroidism with a total iodide organification defect, and residual in vitro enzymatic activity quantitatively tracks clinical severity [#2, #3]. Separately, thrombopoietin is a hematopoietic cytokine that signals through the receptor c-Mpl to control megakaryocyte number, polyploidization, and platelet production, as well as hematopoietic stem cell self-renewal [#14]. Ligand engagement activates JAK2 (but not JAK1) and the STAT5/STAT3, PI3K/Akt, and Ras/MAPK arms [#5, #8, #15], with receptor tyrosine Y112 recruiting Gab1/Gab2 to drive PI3K/Akt and proliferation [#7], and the adaptor Lnk acting through its SH2 domain as a negative regulator of these outputs [#6]. The balance between proliferation and differentiation is set by the relative levels of JAK2 and MPL protein and by opposing MEK/ERK versus PI3K/Akt/mTOR control of ploidy [#10, #11].\",\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Establishing the immediate signaling output of thrombopoietin defined how c-Mpl engagement is transduced, showing it activates the JAK-STAT axis and selectively engages JAK2 rather than JAK1.\",\n      \"evidence\": \"EMSA, tyrosine phosphorylation and immunoprecipitation assays in hematopoietic and myeloid precursor cells, including a JAK1 negative control distinguishing TPO from IL-3\",\n      \"pmids\": [\"7544303\", \"7545904\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not resolve which STAT outputs drive proliferation versus differentiation\", \"Direct receptor residues coupling c-Mpl to JAK2 not mapped here\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Identification of a TPO-dependent megakaryoblastic cell line and the Grb2/JAK2/c-Cbl complex clarified how the receptor nucleates downstream adaptors distinct from receptor tyrosine kinase signaling.\",\n      \"evidence\": \"JAK2/STAT5 phosphorylation in UT-7/TPO cells and Co-IP comparing TPO/c-Mpl versus SCF/c-Kit adaptor recruitment\",\n      \"pmids\": [\"8639823\", \"8950973\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of the Grb2/JAK2 complex on cell fate not isolated\", \"c-Cbl downstream role undefined\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Genetic ablation of TPO and c-Mpl established the physiological role of the cytokine as a controller of megakaryocyte/platelet number and a regulator of HSC repopulation, with a platelet-mass feedback loop.\",\n      \"evidence\": \"TPO and c-Mpl knockout mice with platelet counts, progenitor enumeration, BM repopulation assays, and platelet receptor-binding analysis\",\n      \"pmids\": [\"9474742\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of HSC self-renewal effect not defined here\", \"Does not explain ploidy control mechanism\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Assigning the catalytic residues of thyroid peroxidase and correlating them with the inactive splice variant explained the structural requirements for peroxidase activity.\",\n      \"evidence\": \"Sequence alignment with myeloperoxidase identifying His239/His494/Asn579/Arg396 plus functional correlation with activity-null TPO-2 lacking residues 533–589\",\n      \"pmids\": [\"9510129\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct site-directed mutagenesis of individual residues reported\", \"Compound I formation role of Arg396 inferred by analogy\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Mapping c-Mpl Y112 to Gab1/Gab2 recruitment defined the receptor module that couples thrombopoietin to PI3K/Akt and proliferation.\",\n      \"evidence\": \"Co-IP of Gab1/2 with Shc/SHP2/PI3K/Grb2 and Y112 mutant c-Mpl analysis in UT7 and primary megakaryocytic progenitors\",\n      \"pmids\": [\"11402314\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Why only Gab1 is expressed in primary progenitors not explained\", \"Quantitative contribution of PI3K versus other arms to proliferation not partitioned\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Identifying PLZF/GATA1 control of the TpoR promoter showed how receptor expression itself is transcriptionally set during megakaryocytic commitment.\",\n      \"evidence\": \"Promoter deletion mapping and PLZF/GATA1 Co-IP in retrovirally transduced TF1 cells\",\n      \"pmids\": [\"12242665\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct DNA-binding stoichiometry of the PLZF/GATA1 complex not resolved\", \"In vivo relevance to receptor levels not tested\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Dissection of the MAPK branch separated essential from dispensable kinases, showing Raf-1 is not required while p38 links TPO to Hoxb4 via USF-1 for HSC self-renewal.\",\n      \"evidence\": \"raf-1 knockout mice with ERK readouts and p38-inhibitor/USF-1 induction analysis with tpo-/- HSC comparison\",\n      \"pmids\": [\"14576068\", \"12855555\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which Raf isoform substitutes for Raf-1 in ERK activation not identified\", \"Magnitude of Hoxb4 change (2–5 fold) leaves quantitative contribution to self-renewal uncertain\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Tracing c-myc induction to a PI3K/MAPK route independent of Akt/mTOR refined which downstream effectors control megakaryocyte transcriptional output.\",\n      \"evidence\": \"qRT-PCR of c-myc with PI3K/MAPK/Akt/PKCζ/mTOR inhibitors and active-Akt overexpression in UT-7, BaF3/Mpl, and primary megakaryocytes\",\n      \"pmids\": [\"16380230\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The PI3K effector bridging to c-myc independent of Akt not identified\", \"Direct transcriptional mediator at the c-myc locus undefined\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Defining opposing MEK/ERK and PI3K/AKT/mTOR effects on ploidy, with cyclin D3 localization as readout, established how a single ligand balances proliferation against polyploidization.\",\n      \"evidence\": \"PD98059 and rapamycin treatment with ploidy flow cytometry and cyclin D3 immunolocalization in human CD34+-derived megakaryocytes\",\n      \"pmids\": [\"16449323\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking mTOR to nuclear cyclin D3 retention not resolved\", \"Single-lab pharmacology without genetic confirmation\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Identifying Lnk as an SH2-dependent negative regulator placed a brake on the breadth of TPO signaling outputs.\",\n      \"evidence\": \"Lnk overexpression and knockout mice with STAT3/STAT5/Akt/MAPK phosphorylation, domain-deletion mutants, and megakaryocyte colony assays\",\n      \"pmids\": [\"15337790\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The phosphotyrosine docking site engaged by the Lnk SH2 domain not mapped\", \"PH domain contribution mechanism unresolved\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Consolidating TPO genetics fixed thyroid peroxidase as the enzyme whose loss causes a total iodide organification defect and congenital hypothyroidism.\",\n      \"evidence\": \"Functional/genetic analysis of TPO mutations across congenital hypothyroidism cohorts (review of 61 mutations)\",\n      \"pmids\": [\"20153806\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Per-residue structural consequences not yet linked to mechanism at this stage\", \"Genotype-phenotype quantitation not established here\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Showing that JAK2 and MPL protein levels dictate proliferation-versus-differentiation outcome revealed a dosage logic, including a paradoxical pro-megakaryocytic effect of low-dose JAK2 inhibition.\",\n      \"evidence\": \"siRNA knockdown of JAK2/MPL, JAK2 chemical inhibition, in vitro/in vivo differentiation assays, and patient-sample Western blots\",\n      \"pmids\": [\"25143485\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative thresholds of JAK2/MPL setting each fate not defined\", \"How the same kinase output is interpreted as opposite fates remains unresolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Demonstrating that thrombopoietin drives metabolic reprogramming in colorectal tumor-initiating cells extended its signaling into oncogenic self-renewal beyond hematopoiesis.\",\n      \"evidence\": \"Metabolic profiling, acetylation/Wnt/redox assays, c-myc loss-of-function in CD110+ TICs and in vivo liver metastasis models\",\n      \"pmids\": [\"26140605\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Generality across cancer types not established\", \"Direct receptor coupling to lysine degradation enzymes not mapped\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identifying breast-expressed thyroid peroxidase and its predominantly cytoplasmic distribution showed enzymatic activity depends on apical/cell-surface presentation absent in mammary cells.\",\n      \"evidence\": \"Western blot, glycosylation analysis, isoelectric focusing, peroxidase activity assays, and subcellular localization in breast-derived cell lines\",\n      \"pmids\": [\"29513734\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional role of cytoplasmic breast TPO undefined\", \"Trafficking defect mechanism not identified\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Linking thyroid TPO downregulation to a p38/TRHr pathway revealed an environmental-chemical route by which TPO expression is suppressed.\",\n      \"evidence\": \"Rat triclosan exposure with Nthy-ori 3-1 p38 inhibitor and TRHr siRNA experiments measuring TPO expression\",\n      \"pmids\": [\"29462796\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct transcriptional mechanism downstream of TRHr on the TPO gene not defined\", \"Generalizability beyond triclosan unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Showing thrombopoietin and c-Mpl expression in CNS neurons with PI3K/Akt-mediated neuroprotection extended the cytokine's anti-apoptotic signaling to a non-hematopoietic tissue.\",\n      \"evidence\": \"Human CNS immunohistochemistry, neonatal rat hypoxic-ischemic model, and PI3K/Akt and Bcl-2/BAX pathway analysis with proliferation/apoptosis assays\",\n      \"pmids\": [\"32341206\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological role of neuronal TPO under non-injury conditions unknown\", \"Single-lab finding without independent confirmation\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"The first high-resolution structure of thyroid peroxidase resolved its domain architecture, the disulfide stabilizing it, and the spatial separation of catalytic site from autoantibody epitopes.\",\n      \"evidence\": \"Cryo-EM of the TPO extracellular domain at 3.4–3.92 Å complexed with two independent Fab fragments\",\n      \"pmids\": [\"36537574\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Membrane-anchored full-length conformation not resolved\", \"Catalytic cycle intermediates not captured structurally\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how the same intracellular kinase modules are quantitatively interpreted to produce opposite megakaryocyte fates, and whether the non-hematopoietic thrombopoietin roles (CNS, tumor metabolism) operate through the canonical c-Mpl module.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified quantitative model linking JAK2/MPL dosage to fate\", \"Receptor coupling for metabolic and neuroprotective effects not mapped\", \"Structural basis of thyroid TPO catalysis at the membrane unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016491\", \"supporting_discovery_ids\": [0, 1, 2, 3]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [5, 7, 8, 15]},\n      {\"term_id\": \"GO:0048018\", \"supporting_discovery_ids\": [5, 14]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [5, 7, 14]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [16]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [5, 7, 8, 11]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [2, 3]},\n      {\"term_id\": \"R-HSA-109582\", \"supporting_discovery_ids\": [14, 16]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [11, 14, 13]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"MPL\", \"JAK2\", \"STAT5\", \"STAT3\", \"Gab1\", \"Gab2\", \"Grb2\", \"Lnk\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":7,"faith_total":7,"faith_pct":100.0}}