{"gene":"PDZK1IP1","run_date":"2026-06-10T05:19:53","timeline":{"discoveries":[{"year":1996,"finding":"MAP17 (DD96/PDZK1IP1) is a 17 kDa membrane-associated protein localized to the brush border of proximal tubular epithelial cells in normal kidney, and to cell membranes at areas of cell-cell contact in tissue culture. Transfection of full-length DD96 cDNA into HT-29 colon carcinoma cells markedly decreased cell proliferation in vitro and tumor growth in vivo.","method":"Polyclonal antibody characterization, immunolocalization, cDNA transfection with in vitro proliferation assay and in vivo tumor growth assay","journal":"The American journal of pathology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single lab, direct protein localization and functional transfection experiments with two orthogonal readouts (in vitro and in vivo)","pmids":["8701988"],"is_preprint":false},{"year":2003,"finding":"MAP17 interacts specifically with the fourth PDZ domain of PDZK1 (but not other PDZ proteins in the proximal tubule brush border), associates with the NH2-terminus of NaPi-IIa within a PDZK1/NaPi-IIa/MAP17 complex, and acts as an apical anchoring site for PDZK1. MAP17 apical localization is independent of PDZK1, but MAP17 is required for apical localization of PDZK1 in opossum kidney cells.","method":"Yeast two-hybrid screen, in vitro binding assays, immunofluorescence, transfection studies in opossum kidney (OK) cells","journal":"American journal of physiology. Renal physiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (yeast two-hybrid, in vitro assays, immunofluorescence, cell transfection) establishing complex membership and localization dependency","pmids":["12837682"],"is_preprint":false},{"year":2003,"finding":"Rat kidney MAP17 induces high-affinity, Na-dependent cotransport of D-mannose and D-glucose in Xenopus laevis oocytes, likely by stimulating an endogenous oocyte transport system. MAP17 spans the membrane twice with both termini inside the cell, and forms homodimers through intracellular Cys55; mutation of Cys55 abolishes transport activity.","method":"Expression cloning in Xenopus oocytes, transport assays, site-directed mutagenesis (Cys55), membrane topology analysis","journal":"American journal of physiology. Renal physiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — functional reconstitution in oocytes combined with mutagenesis establishing structure-function relationship","pmids":["12812916"],"is_preprint":false},{"year":2003,"finding":"SPAP (MAP17/DD96/PDZK1IP1) is an in vivo PDZK1-interacting protein in liver. Hepatic overexpression of SPAP in transgenic mice leads to degradation of PDZK1 via a proteasome-independent pathway, resulting in loss of SR-BI from the liver cell surface and markedly elevated plasma HDL levels.","method":"In vivo transgenic mouse model, metabolic labeling, proteasome inhibitor experiments, Western blot","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo transgenic model with metabolic labeling and proteasome pathway dissection, multiple orthogonal methods","pmids":["12754212"],"is_preprint":false},{"year":2006,"finding":"MAP17 interacts with all four NHERF proteins, NaPi-IIa, and NHE3 via its PDZ-binding domain. Co-expression of MAP17 with NHERF3 or NHERF4 (but not NHERF1/2) induces internalization of NaPi-IIa, MAP17, and the PDZ protein to the trans-Golgi network (TGN). This internalization is prevented by PKC inhibition and is triggered by PKC activation or dopamine D1-like receptor activation. Co-transfection of MAP17 and NHERF3 prevents adaptive upregulation of phosphate transport in response to low phosphate.","method":"Bacterial and mammalian two-hybrid systems, transfection in OK cells, immunofluorescence, PKC inhibition/activation assays, lysosomal inhibition, dopamine receptor activation","journal":"American journal of physiology. Renal physiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — two orthogonal two-hybrid systems plus multiple pharmacological interventions with functional transport readout in a single study","pmids":["16926447"],"is_preprint":false},{"year":2007,"finding":"MAP17 overexpression in tumor cells increases reactive oxygen species (ROS) production, enhancing proliferation, migration, resistance to apoptosis, and tumor growth in nude mice. The tumorigenic effects are abolished by antioxidant treatment. MAP17-dependent ROS increase requires its PDZ-binding domain, as point mutations disrupting this domain abolish ROS production and tumorigenesis. Na+-coupled co-transporter inhibitors reduce ROS increase and malignant behavior.","method":"Stable transfection in tumor cell lines, ROS measurement, antioxidant treatment, PDZ-binding domain point mutagenesis, nude mouse tumor assay, Na+-coupled cotransporter inhibition","journal":"Carcinogenesis","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods including mutagenesis, pharmacological inhibition, and in vivo tumor assay establishing mechanism","pmids":["17548903"],"is_preprint":false},{"year":2007,"finding":"MAP17 overexpression in Rat1a fibroblasts protects against Myc-induced apoptosis through ROS-mediated activation of the PI3K/AKT signaling pathway. This is associated with absence of Bax translocation to mitochondria, reduced caspase-3 activation, and oxidation of a fraction of PTEN. AKT activation (Thr308 phosphorylation) by MAP17 is independent of PI3K activity. Antioxidant treatment prevents AKT activation and restores apoptosis.","method":"Stable transfection in Rat1a cells, apoptosis assays, Bax translocation, caspase-3 activation measurement, PTEN oxidation assay, PI3K inhibition, dominant-negative AKT overexpression, antioxidant treatment","journal":"Carcinogenesis","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal biochemical assays and genetic tools (dominant-negative AKT) establishing pathway mechanism in single study","pmids":["17675338"],"is_preprint":false},{"year":2007,"finding":"MAP17 expression bypasses TNF-alpha-induced G1 growth arrest by impairing p21waf1 induction in tumor cells, but does not inhibit TNF-induced apoptosis. The effect is specific to TNF and does not alter IFN-gamma response.","method":"Large-scale genetic screen, cell cycle analysis, p21waf1 Western blot, cytokine treatment assays","journal":"Journal of cellular biochemistry","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — functional screen with molecular follow-up (p21 measurement), single lab","pmids":["17230460"],"is_preprint":false},{"year":2009,"finding":"Overexpression of MAP17 in HaCaT keratinocytes significantly decreases the expression of filaggrin, suggesting that Th cell cytokine-induced up-regulation of MAP17 may link to down-regulation of filaggrin and abnormal epidermal differentiation.","method":"Microarray meta-analysis, cytokine stimulation of NHEK cells, MAP17 overexpression in HaCaT cells, gene expression analysis","journal":"Experimental dermatology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single overexpression experiment in keratinocytes with gene expression readout only, single lab","pmids":["19601982"],"is_preprint":false},{"year":2012,"finding":"In non-tumoral breast epithelial cells, MAP17-induced ROS triggers a senescence-like response mediated by p38α activation. In tumor cells lacking p38α phosphorylation, MAP17-induced ROS instead enhances tumorigenic properties. Knockdown of MAP17 in protein-expressing tumor cells reduces tumorigenic capabilities.","method":"Stable transfection and shRNA knockdown in breast cell lines, ROS measurement, senescence assays, p38α activation/phosphorylation analysis, tumor growth assays","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function and gain-of-function with molecular pathway readout (p38α), single lab","pmids":["22266858"],"is_preprint":false},{"year":2015,"finding":"MAP17 is associated with proteins involved in protein degradation and suppresses bortezomib-induced cytoprotective autophagy and NFκB nuclear translocation in breast cancer cells both in vitro and in vivo. This MAP17-induced sensitivity to bortezomib depends on oxidative status and Na+-coupled transporter activity, as antioxidants or furosemide treatment restores cytoprotective responses.","method":"In vitro bortezomib treatment, autophagy assay, NFκB nuclear translocation assay, antioxidant treatment, furosemide inhibition, xenograft tumor model","journal":"Molecular cancer therapeutics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple assays including in vivo xenograft, pharmacological dissection, single lab","pmids":["25837675"],"is_preprint":false},{"year":2016,"finding":"MAP17 is a necessary activator of SGLT2 (SLC5A2): co-expression of MAP17 with SGLT2 in Xenopus oocytes increases SGLT2 activity by two orders of magnitude, and significant stimulation also occurs in opossum kidney cells co-transfected with SGLT2 and MAP17. MAP17 does not change the quantity of SGLT2 protein at the cell surface. A patient with familial renal glucosuria without SGLT2 mutations was found to carry a homozygous splicing mutation in PDZK1IP1 (c.176+1G>A).","method":"Expression cloning in Xenopus oocytes, glucose transport assay, co-transfection in opossum kidney cells, cell surface SGLT2 quantification, genetic analysis of patient cohort","journal":"Journal of the American Society of Nephrology : JASN","confidence":"High","confidence_rationale":"Tier 1 / Strong — functional reconstitution in two heterologous systems (oocytes and mammalian cells), corroborated by human genetic evidence, multiple orthogonal methods","pmids":["27288013"],"is_preprint":false},{"year":2017,"finding":"MAP17 (PDZK1IP1) interacts with NUMB through its PDZ-binding domain, sequestering NUMB and thereby activating the Notch signaling pathway. This leads to increased stem cell factor expression and expansion of cancer stem-like cells. MAP17 downregulation in tumor cell lines reduces Notch pathway activation and stemness. MAP17 levels directly correlate with tumorsphere formation capability in PDX models.","method":"Co-immunoprecipitation, PDZ-binding domain interaction studies, Notch pathway reporter assays, MAP17 overexpression/knockdown in cell lines, tumorsphere formation assay, PDX models","journal":"Clinical cancer research","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal binding assays, loss/gain-of-function experiments, in vivo PDX validation, multiple orthogonal methods in single study","pmids":["28153862"],"is_preprint":false},{"year":2017,"finding":"MAP17 expression directly regulates NFAT2 and IL-6 activation and induces differentiation of monocytes to dendritic cells, suggesting a causal role for MAP17 in inflammation.","method":"MAP17 overexpression experiments, NFAT2 and IL-6 reporter/activation assays, monocyte differentiation assay","journal":"Oncotarget","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, limited methodological details in abstract","pmids":["29228712"],"is_preprint":false},{"year":2018,"finding":"MAP17 colocalizes and co-immunoprecipitates with SGLT2 in HEK293T cells co-expressing V5-tagged SGLT2 and HA-tagged MAP17. In human kidney sections, both proteins overlap at the apical surface of tubular epithelia.","method":"Co-immunoprecipitation, colocalization by immunofluorescence in HEK293T cells, immunohistochemistry in human kidney sections","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP with colocalization, corroborating prior functional data, single lab","pmids":["30156268"],"is_preprint":false},{"year":2019,"finding":"PDZK1IP1 (MAP17) interacts with Smad4 protein. PDZK1IP1 inhibits both TGF-β and BMP signaling pathways without affecting R-Smad phosphorylation, instead interfering with R-Smad/Smad4 complex formation and retaining Smad4 in the cytoplasm. The middle region of PDZK1IP1 (Phe40–Ala49) is required for Smad4-regulating activity. PDZK1IP1 knockdown enhances TGF-β target gene expression; overexpression suppresses TGF-β-induced reporter activity, cell migration, and cell growth inhibition, and decreases tumor size in a xenograft model.","method":"Co-immunoprecipitation, PDZK1IP1 deletion/variant mutagenesis, R-Smad phosphorylation assays, Smad complex formation assay, cytoplasmic/nuclear fractionation, TGF-β reporter assay, siRNA knockdown, cell migration assay, xenograft tumor model","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods including Co-IP, domain mutagenesis, fractionation, loss/gain-of-function with pathway and in vivo readouts, single lab","pmids":["30718277"],"is_preprint":false},{"year":2020,"finding":"MAP17 increases exosome production in breast cancer tumor cells, and MAP17 protein is released as cargo in exosomes. Exosomal MAP17 transfer to recipient cells increases EMT. An antibody against MAP17 in conditioned media reduces EMT and stemness alterations in recipient cells. MAP17 expression is regulated by demethylation-induced miRNA changes dependent on Notch pathway activation.","method":"Exosome isolation, Western blot for MAP17 in exosomes, conditioned media transfer experiments, EMT and stemness assays, antibody blocking experiment, methylation analysis","journal":"Oncogenesis","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — exosome cargo identification with functional transfer and antibody blocking, single lab","pmids":["33106480"],"is_preprint":false},{"year":2021,"finding":"MAP17 expression is hypoxia-dependent in HCC. MAP17 knockdown reduces glucose uptake, lactate release, extracellular acidification rate, and glycolytic gene expression. Ectopic expression of wild-type MAP17, but not a PDZ-binding domain mutant (MAP17-PDZm), increases tumor glycolysis. Mechanistically, MAP17 increases ROS, which activates AKT and HIF1α downstream effectors to enhance the Warburg effect. RNA sequencing after MAP17 knockdown reveals transcriptional changes in ROS metabolic processes.","method":"Gain/loss-of-function studies, PDZ-binding domain mutagenesis, Seahorse metabolic assay, ROS measurement, co-immunoprecipitation, immunofluorescence, Western blotting, RNA sequencing, xenograft tumor model","journal":"Journal of experimental & clinical cancer research","confidence":"High","confidence_rationale":"Tier 2 / Strong — PDZ domain mutagenesis with mechanistic pathway dissection (ROS→AKT/HIF1α), multiple orthogonal methods including in vivo xenograft","pmids":["33832535"],"is_preprint":false},{"year":2023,"finding":"FXR1 negatively regulates PDZK1IP1 mRNA by promoting its degradation via direct interaction with the 3'UTR of PDZK1IP1. PDZK1IP1 overexpression inhibits the tumor-promotive phenotype in FXR1-overexpressed esophageal cancer cells.","method":"RNA-binding protein immunoprecipitation, mRNA stability assay, 3'UTR interaction analysis, PDZK1IP1 overexpression rescue experiments, xenograft tumor model","journal":"Biology direct","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct 3'UTR interaction with mRNA stability measurement and functional rescue, single lab","pmids":["39511680"],"is_preprint":false},{"year":2023,"finding":"Fenofibrate binds tightly to PDZK1IP1 protein (assessed by molecular docking), inhibits its hepatic expression in NIAAA model mice independently of PPARα signaling, and reduces lipid deposition, oxidative stress and inflammation.","method":"Molecular docking, Western blot in mouse liver, PPARα gene silencing, NIAAA alcoholic liver disease mouse model","journal":"Life sciences","confidence":"Low","confidence_rationale":"Tier 3 / Weak — molecular docking for binding (computational) with in vivo expression readout only; mechanism primarily inferred rather than reconstituted","pmids":["38042280"],"is_preprint":false},{"year":2023,"finding":"MAP17 up-regulation in kidneys of diabetic mice is observed with combined empagliflozin (SGLT2i) and ramipril (RAS blocker) treatment, suggesting MAP17 acts as a scaffolding protein placing SGLT2 and NHE3 together in proximal tubular cells.","method":"High-throughput proteomic analysis by TMT-labeled mass spectrometry, Western blot validation in db/db diabetic mouse kidneys","journal":"Clinical science","confidence":"Low","confidence_rationale":"Tier 3 / Weak — proteomic screen with Western blot validation, mechanistic interpretation is inferential rather than experimentally proven in this study","pmids":["36524468"],"is_preprint":false},{"year":2024,"finding":"miR-455-5p directly suppresses PDZK1IP1 (MAP17) expression by targeting it post-transcriptionally. PDZK1IP1 knockdown promotes migration, metastasis, EMT, and increases TGF-β signaling in OSCC cells.","method":"Dual-luciferase reporter assay, qRT-PCR, wound-healing assay, transwell invasion assay, in vivo metastasis assay, nuclear/cytoplasmic fractionation, Western blot","journal":"Journal of experimental & clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — dual-luciferase confirms miR-455-5p→PDZK1IP1 targeting, loss-of-function with functional readouts, single lab","pmids":["36737832"],"is_preprint":false},{"year":2026,"finding":"MAP17 activates the RELA-dependent NF-κB pathway in glioblastoma-initiating cells (GICs), increasing BCL2 expression, which promotes TMZ resistance and tumorigenicity. MAP17 overexpression in GICs increases proliferation, TMZ resistance, and tumorigenicity; knockdown impairs these properties. BCL2 overexpression phenocopies MAP17 overexpression, and BCL2 knockdown impairs TMZ resistance in MAP17-high resistant GICs.","method":"Stable overexpression and shRNA knockdown in GICs, gene expression profiling, NF-κB pathway assays, BCL2 overexpression/knockdown, TMZ resistance assays, tumorigenicity assays","journal":"Cancer science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis via gain/loss-of-function for MAP17-NF-κB-BCL2 pathway, single lab","pmids":["42043964"],"is_preprint":false},{"year":2026,"finding":"In rats with congestive heart failure (CHF), renal sympathetic nerve activity activates the ERK/NF-κB pathway, which increases SGLT2, MAP17, and PDZK1 expression and their translocation to the luminal membrane. Renal denervation mitigates enhanced expression of the SGLT2-MAP17-PDZK1 complex. Norepinephrine directly triggers SGLT2-MAP17-PDZK1 upregulation via ERK/NF-κB in human proximal tubular cells.","method":"Coronary artery ligation CHF rat model, bilateral renal denervation, Western blot, immunohistochemistry, norepinephrine treatment of human proximal tubular cells","journal":"Hypertension","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo denervation model with in vitro mechanistic confirmation via norepinephrine treatment; single lab","pmids":["41549941"],"is_preprint":false},{"year":2025,"finding":"SGLT2 is enriched within proximal tubular microvilli and partially colocalizes with its co-factor PDZK1IP1 (MAP17) at this subcellular location, as shown using knockout-validated antibodies in rodent and human kidney tissue.","method":"Immunohistochemistry with SGLT2-knockout rodent negative controls, subcellular colocalization analysis","journal":"bioRxiv (preprint)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — knockout-validated antibody with colocalization, rigorous negative controls, single preprint study","pmids":[],"is_preprint":true}],"current_model":"PDZK1IP1/MAP17 is a small (17 kDa), non-glycosylated, dual-pass membrane protein that acts as an obligate accessory/scaffolding unit for the renal Na⁺-glucose cotransporter SGLT2 (increasing its activity ~100-fold), anchors PDZK1 to the apical membrane of proximal tubular cells, forms a NaPi-IIa/PDZK1/MAP17 complex, regulates NaPi-IIa internalization via NHERF3/4 interaction in a PKC-dependent manner, promotes tumorigenic signaling through its PDZ-binding domain by increasing ROS to activate PI3K/AKT and HIF1α, activates Notch signaling by sequestering NUMB, suppresses TGF-β signaling by trapping Smad4 in the cytoplasm and blocking R-Smad/Smad4 complex formation, and drives chemoresistance in glioblastoma-initiating cells via NF-κB-dependent BCL2 upregulation."},"narrative":{"mechanistic_narrative":"PDZK1IP1 (MAP17/DD96/SPAP) is a small dual-pass membrane protein of the proximal tubule brush border that functions both as an obligate accessory subunit for renal sodium-coupled transporters and as a membrane scaffold whose dysregulation drives oncogenic signaling [PMID:8701988, PMID:12812916, PMID:27288013]. In the kidney it spans the membrane twice with both termini intracellular, homodimerizes through intracellular Cys55, and is a necessary activator of the Na⁺-glucose cotransporter SGLT2, increasing its activity by roughly two orders of magnitude without altering surface SGLT2 abundance; a homozygous PDZK1IP1 splicing mutation causes familial renal glucosuria, establishing this transporter-activating role in human physiology [PMID:12812916, PMID:27288013, PMID:30156268]. Through its C-terminal PDZ-binding domain it interacts with the fourth PDZ domain of PDZK1, anchoring PDZK1 to the apical membrane and assembling a PDZK1/NaPi-IIa/MAP17 complex, and engages NHERF3/NHERF4 to drive PKC-dependent internalization of NaPi-IIa toward the trans-Golgi network, thereby regulating phosphate transport [PMID:12837682, PMID:12754212, PMID:16926447]. The same PDZ-binding domain underlies its tumorigenic activity: MAP17 overexpression elevates reactive oxygen species in a manner dependent on Na⁺-coupled cotransport, and this ROS signal activates PI3K/AKT and HIF1α to enhance proliferation, apoptosis resistance, and Warburg-type glycolysis, while ROS instead triggers p38α-dependent senescence in non-transformed cells [PMID:17548903, PMID:17675338, PMID:22266858, PMID:33832535]. MAP17 additionally activates Notch signaling by sequestering NUMB to expand cancer stem-like cells, suppresses TGF-β and BMP signaling by binding Smad4 through its central Phe40–Ala49 region and retaining it in the cytoplasm to block R-Smad/Smad4 complex formation, and confers therapy resistance via NF-κB-dependent BCL2 upregulation in glioblastoma-initiating cells and suppression of bortezomib-induced cytoprotective autophagy in breast cancer [PMID:28153862, PMID:30718277, PMID:42043964, PMID:25837675]. Its expression is post-transcriptionally constrained by FXR1 and miR-455-5p [PMID:39511680, PMID:36737832].","teleology":[{"year":1996,"claim":"Established the existence and tissue distribution of MAP17 and the first functional clue that it could restrain epithelial tumor growth, framing the protein as both a kidney brush-border component and a growth modulator.","evidence":"Antibody immunolocalization and cDNA transfection with in vitro proliferation and in vivo tumor growth assays in colon carcinoma cells","pmids":["8701988"],"confidence":"Medium","gaps":["No molecular mechanism for growth suppression","No binding partners identified","Contrasts with later pro-tumorigenic findings, suggesting context dependence not resolved here"]},{"year":2003,"claim":"Defined MAP17 as a PDZ-domain scaffold partner and a transport-activating membrane protein, answering how it physically couples to the brush-border transport machinery.","evidence":"Yeast two-hybrid, in vitro binding, immunofluorescence in OK cells, plus expression cloning in Xenopus oocytes with Cys55 mutagenesis and topology analysis","pmids":["12837682","12812916","12754212"],"confidence":"High","gaps":["Identity of the endogenous oocyte transporter being stimulated not defined","Mechanism of PDZK1 degradation upon hepatic overexpression unresolved","Direct vs indirect basis of transport stimulation unclear"]},{"year":2006,"claim":"Showed MAP17 organizes regulated trafficking of phosphate transport, linking the scaffold to NHERF3/4-dependent, PKC-controlled internalization rather than static anchoring.","evidence":"Bacterial and mammalian two-hybrid systems with PKC/dopamine receptor pharmacology and transport assays in OK cells","pmids":["16926447"],"confidence":"High","gaps":["In vivo physiological relevance of TGN-directed internalization not tested","Selectivity for NHERF3/4 over NHERF1/2 mechanistically unexplained"]},{"year":2007,"claim":"Reframed MAP17 from growth suppressor to oncogenic driver by identifying ROS production through its PDZ-binding domain as the upstream event activating PI3K/AKT and bypassing apoptotic checkpoints.","evidence":"Stable transfection in tumor and Rat1a cells with ROS measurement, PDZ-domain mutagenesis, antioxidant rescue, dominant-negative AKT, and nude mouse tumor assays; plus a genetic screen for TNF-induced arrest bypass","pmids":["17548903","17675338","17230460"],"confidence":"High","gaps":["Source of MAP17-driven ROS not molecularly defined","How AKT Thr308 phosphorylation occurs independently of PI3K unexplained","Reconciliation with earlier growth-suppressive role incomplete"]},{"year":2012,"claim":"Resolved the suppressor/promoter paradox by showing the same ROS signal produces p38α-dependent senescence in normal cells but tumorigenic enhancement where p38α signaling is lost, making cellular context the determinant of outcome.","evidence":"Gain- and loss-of-function in breast cell lines with ROS, senescence, p38α phosphorylation, and tumor growth assays","pmids":["22266858"],"confidence":"Medium","gaps":["Single lab","Threshold of p38α activity that switches outcomes not quantified"]},{"year":2016,"claim":"Established MAP17 as a necessary activator of SGLT2 and linked PDZK1IP1 loss to human disease, anchoring its physiological transport role in genetics.","evidence":"Expression cloning in oocytes and OK cells, surface SGLT2 quantification, and identification of a homozygous PDZK1IP1 splicing mutation in familial renal glucosuria","pmids":["27288013"],"confidence":"High","gaps":["Structural basis of SGLT2 activation without changing surface levels unknown","Whether activation requires homodimerization not tested for SGLT2 specifically"]},{"year":2017,"claim":"Identified NUMB sequestration as a discrete oncogenic mechanism, explaining how MAP17 activates Notch signaling and expands cancer stem-like cells beyond its ROS activity.","evidence":"Co-immunoprecipitation, PDZ-binding domain interaction studies, Notch reporter assays, knockdown, and tumorsphere/PDX models","pmids":["28153862"],"confidence":"High","gaps":["Stoichiometry of NUMB sequestration not defined","Crosstalk between NUMB/Notch and ROS/AKT arms unresolved"]},{"year":2019,"claim":"Defined a Smad4-trapping mechanism mapped to the central Phe40–Ala49 region, showing MAP17 suppresses TGF-β/BMP signaling without altering R-Smad phosphorylation.","evidence":"Co-IP, deletion mutagenesis, R-Smad phosphorylation assays, nuclear/cytoplasmic fractionation, reporter assays, and xenograft model","pmids":["30718277"],"confidence":"High","gaps":["How a membrane protein retains Smad4 cytoplasmically not structurally explained","Interplay with PDZ-domain-dependent functions not addressed"]},{"year":2021,"claim":"Integrated the ROS arm into tumor metabolism, showing MAP17 drives the Warburg effect via ROS-mediated AKT and HIF1α activation in a PDZ-binding-domain-dependent manner.","evidence":"Gain/loss-of-function with PDZ-domain mutant, Seahorse metabolic assays, ROS measurement, RNA-seq, and xenograft model in HCC","pmids":["33832535"],"confidence":"High","gaps":["Direct connection between transporter activity and HIF1α stabilization not biochemically dissected"]},{"year":2023,"claim":"Placed PDZK1IP1 under post-transcriptional control and extended its scaffolding role to renal stress responses, defining regulatory inputs and an in vivo transporter-complex context.","evidence":"RNA-IP and 3'UTR/mRNA stability assays (FXR1), proteomic and Western analyses in diabetic and heart-failure renal models, and molecular docking for fenofibrate","pmids":["39511680","36524468","38042280"],"confidence":"Medium","gaps":["Fenofibrate binding inferred from docking only","MAP17 scaffolding of SGLT2/NHE3 in stressed kidney is interpretive in these studies","Direct vs indirect FXR1 effects on downstream phenotype incomplete"]},{"year":2024,"claim":"Added miR-455-5p as a direct repressor and reinforced the TGF-β-suppressive role by showing PDZK1IP1 loss promotes EMT and metastasis.","evidence":"Dual-luciferase reporter, qRT-PCR, migration/invasion and in vivo metastasis assays, and fractionation in OSCC cells","pmids":["36737832"],"confidence":"Medium","gaps":["Tissue specificity of tumor-suppressive versus oncogenic behavior not reconciled","Single lab"]},{"year":2026,"claim":"Defined an NF-κB/BCL2 axis underlying therapy resistance and tied renal complex regulation to sympathetic ERK/NF-κB signaling, broadening MAP17's roles in chemoresistance and cardiorenal physiology.","evidence":"Overexpression/knockdown with NF-κB and BCL2 epistasis and TMZ resistance assays in glioblastoma-initiating cells; CHF rat model with renal denervation and norepinephrine treatment of human proximal tubular cells","pmids":["42043964","41549941"],"confidence":"Medium","gaps":["Whether NF-κB activation depends on the ROS or scaffolding arm not resolved","Direct molecular link between MAP17 and RELA activation unknown","Single-lab findings"]},{"year":null,"claim":"How a single small membrane protein integrates its transporter-activating scaffolding function with its multiple cytoplasmic signaling effects (NUMB, Smad4, ROS, NF-κB) at the structural and stoichiometric level remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of MAP17 or its complexes","Mechanism linking Na⁺-coupled transport to ROS generation undefined","No unified model reconciling growth-suppressive and oncogenic contexts"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,4,11,15]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[2,11,5]},{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[2,11]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,1,11,14,24]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[4]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[15]}],"pathway":[{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[2,11,4]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[12,15,22,17]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[11,5,17]}],"complexes":["PDZK1/NaPi-IIa/MAP17 complex","SGLT2-MAP17-PDZK1 complex"],"partners":["PDZK1","SLC5A2","NAPI-IIA","NHERF3","NHERF4","NHE3","NUMB","SMAD4"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q13113","full_name":"PDZK1-interacting protein 1","aliases":["17 kDa membrane-associated protein","Protein DD96"],"length_aa":114,"mass_kda":12.2,"function":"Auxiliary protein of electrogenic Na(+)-coupled sugar symporter SLC5A2/SGLT2 and SLC5A1/SGLT1 (PubMed:34880493, PubMed:37217492, PubMed:38057552). 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science","url":"https://pubmed.ncbi.nlm.nih.gov/42043964","citation_count":0,"is_preprint":false},{"pmid":"41761346","id":"PMC_41761346","title":"Pan-cancer analysis of PDZK1IP1 reveals its role in tumorigenesis and tumor immunity: focused validation in thyroid carcinoma.","date":"2026","source":"Hereditas","url":"https://pubmed.ncbi.nlm.nih.gov/41761346","citation_count":0,"is_preprint":false},{"pmid":"41412792","id":"PMC_41412792","title":"SPAP: Soluble Human Plasma Proteoform Analysis via Acetonitrile Precipitation and Top-Down Mass Spectrometry.","date":"2025","source":"Journal of the American Society for Mass Spectrometry","url":"https://pubmed.ncbi.nlm.nih.gov/41412792","citation_count":0,"is_preprint":false},{"pmid":"42260473","id":"PMC_42260473","title":"The miR-4512/PDZK1IP1 axis in hepatocellular carcinoma: clinical significance, diagnostic value, and functional validation.","date":"2026","source":"BMC medical genomics","url":"https://pubmed.ncbi.nlm.nih.gov/42260473","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.08.31.672288","title":"Reliable Detection of SGLT2 Protein through Knockout-based Antibody Characterization and Optimized Procedures","date":"2025-09-01","source":"bioRxiv","url":"https://doi.org/10.1101/2025.08.31.672288","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.09.30.25336749","title":"Combination AI-Machine Learning to Diagnose Pulmonary Hypertension: A Real-World Evidence Cohort Study","date":"2025-10-01","source":"bioRxiv","url":"https://doi.org/10.1101/2025.09.30.25336749","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.10.07.24315064","title":"Predictors and outcomes of pulmonary hypertension after mitral valve replacement in severe mitral regurgitation","date":"2024-10-08","source":"bioRxiv","url":"https://doi.org/10.1101/2024.10.07.24315064","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":35972,"output_tokens":6580,"usd":0.103308,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":15645,"output_tokens":4743,"usd":0.0984,"stage2_stop_reason":"end_turn"},"total_usd":0.201708,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1996,\n      \"finding\": \"MAP17 (DD96/PDZK1IP1) is a 17 kDa membrane-associated protein localized to the brush border of proximal tubular epithelial cells in normal kidney, and to cell membranes at areas of cell-cell contact in tissue culture. Transfection of full-length DD96 cDNA into HT-29 colon carcinoma cells markedly decreased cell proliferation in vitro and tumor growth in vivo.\",\n      \"method\": \"Polyclonal antibody characterization, immunolocalization, cDNA transfection with in vitro proliferation assay and in vivo tumor growth assay\",\n      \"journal\": \"The American journal of pathology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single lab, direct protein localization and functional transfection experiments with two orthogonal readouts (in vitro and in vivo)\",\n      \"pmids\": [\"8701988\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"MAP17 interacts specifically with the fourth PDZ domain of PDZK1 (but not other PDZ proteins in the proximal tubule brush border), associates with the NH2-terminus of NaPi-IIa within a PDZK1/NaPi-IIa/MAP17 complex, and acts as an apical anchoring site for PDZK1. MAP17 apical localization is independent of PDZK1, but MAP17 is required for apical localization of PDZK1 in opossum kidney cells.\",\n      \"method\": \"Yeast two-hybrid screen, in vitro binding assays, immunofluorescence, transfection studies in opossum kidney (OK) cells\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (yeast two-hybrid, in vitro assays, immunofluorescence, cell transfection) establishing complex membership and localization dependency\",\n      \"pmids\": [\"12837682\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Rat kidney MAP17 induces high-affinity, Na-dependent cotransport of D-mannose and D-glucose in Xenopus laevis oocytes, likely by stimulating an endogenous oocyte transport system. MAP17 spans the membrane twice with both termini inside the cell, and forms homodimers through intracellular Cys55; mutation of Cys55 abolishes transport activity.\",\n      \"method\": \"Expression cloning in Xenopus oocytes, transport assays, site-directed mutagenesis (Cys55), membrane topology analysis\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — functional reconstitution in oocytes combined with mutagenesis establishing structure-function relationship\",\n      \"pmids\": [\"12812916\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"SPAP (MAP17/DD96/PDZK1IP1) is an in vivo PDZK1-interacting protein in liver. Hepatic overexpression of SPAP in transgenic mice leads to degradation of PDZK1 via a proteasome-independent pathway, resulting in loss of SR-BI from the liver cell surface and markedly elevated plasma HDL levels.\",\n      \"method\": \"In vivo transgenic mouse model, metabolic labeling, proteasome inhibitor experiments, Western blot\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo transgenic model with metabolic labeling and proteasome pathway dissection, multiple orthogonal methods\",\n      \"pmids\": [\"12754212\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"MAP17 interacts with all four NHERF proteins, NaPi-IIa, and NHE3 via its PDZ-binding domain. Co-expression of MAP17 with NHERF3 or NHERF4 (but not NHERF1/2) induces internalization of NaPi-IIa, MAP17, and the PDZ protein to the trans-Golgi network (TGN). This internalization is prevented by PKC inhibition and is triggered by PKC activation or dopamine D1-like receptor activation. Co-transfection of MAP17 and NHERF3 prevents adaptive upregulation of phosphate transport in response to low phosphate.\",\n      \"method\": \"Bacterial and mammalian two-hybrid systems, transfection in OK cells, immunofluorescence, PKC inhibition/activation assays, lysosomal inhibition, dopamine receptor activation\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — two orthogonal two-hybrid systems plus multiple pharmacological interventions with functional transport readout in a single study\",\n      \"pmids\": [\"16926447\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"MAP17 overexpression in tumor cells increases reactive oxygen species (ROS) production, enhancing proliferation, migration, resistance to apoptosis, and tumor growth in nude mice. The tumorigenic effects are abolished by antioxidant treatment. MAP17-dependent ROS increase requires its PDZ-binding domain, as point mutations disrupting this domain abolish ROS production and tumorigenesis. Na+-coupled co-transporter inhibitors reduce ROS increase and malignant behavior.\",\n      \"method\": \"Stable transfection in tumor cell lines, ROS measurement, antioxidant treatment, PDZ-binding domain point mutagenesis, nude mouse tumor assay, Na+-coupled cotransporter inhibition\",\n      \"journal\": \"Carcinogenesis\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods including mutagenesis, pharmacological inhibition, and in vivo tumor assay establishing mechanism\",\n      \"pmids\": [\"17548903\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"MAP17 overexpression in Rat1a fibroblasts protects against Myc-induced apoptosis through ROS-mediated activation of the PI3K/AKT signaling pathway. This is associated with absence of Bax translocation to mitochondria, reduced caspase-3 activation, and oxidation of a fraction of PTEN. AKT activation (Thr308 phosphorylation) by MAP17 is independent of PI3K activity. Antioxidant treatment prevents AKT activation and restores apoptosis.\",\n      \"method\": \"Stable transfection in Rat1a cells, apoptosis assays, Bax translocation, caspase-3 activation measurement, PTEN oxidation assay, PI3K inhibition, dominant-negative AKT overexpression, antioxidant treatment\",\n      \"journal\": \"Carcinogenesis\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal biochemical assays and genetic tools (dominant-negative AKT) establishing pathway mechanism in single study\",\n      \"pmids\": [\"17675338\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"MAP17 expression bypasses TNF-alpha-induced G1 growth arrest by impairing p21waf1 induction in tumor cells, but does not inhibit TNF-induced apoptosis. The effect is specific to TNF and does not alter IFN-gamma response.\",\n      \"method\": \"Large-scale genetic screen, cell cycle analysis, p21waf1 Western blot, cytokine treatment assays\",\n      \"journal\": \"Journal of cellular biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — functional screen with molecular follow-up (p21 measurement), single lab\",\n      \"pmids\": [\"17230460\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Overexpression of MAP17 in HaCaT keratinocytes significantly decreases the expression of filaggrin, suggesting that Th cell cytokine-induced up-regulation of MAP17 may link to down-regulation of filaggrin and abnormal epidermal differentiation.\",\n      \"method\": \"Microarray meta-analysis, cytokine stimulation of NHEK cells, MAP17 overexpression in HaCaT cells, gene expression analysis\",\n      \"journal\": \"Experimental dermatology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single overexpression experiment in keratinocytes with gene expression readout only, single lab\",\n      \"pmids\": [\"19601982\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"In non-tumoral breast epithelial cells, MAP17-induced ROS triggers a senescence-like response mediated by p38α activation. In tumor cells lacking p38α phosphorylation, MAP17-induced ROS instead enhances tumorigenic properties. Knockdown of MAP17 in protein-expressing tumor cells reduces tumorigenic capabilities.\",\n      \"method\": \"Stable transfection and shRNA knockdown in breast cell lines, ROS measurement, senescence assays, p38α activation/phosphorylation analysis, tumor growth assays\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function and gain-of-function with molecular pathway readout (p38α), single lab\",\n      \"pmids\": [\"22266858\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"MAP17 is associated with proteins involved in protein degradation and suppresses bortezomib-induced cytoprotective autophagy and NFκB nuclear translocation in breast cancer cells both in vitro and in vivo. This MAP17-induced sensitivity to bortezomib depends on oxidative status and Na+-coupled transporter activity, as antioxidants or furosemide treatment restores cytoprotective responses.\",\n      \"method\": \"In vitro bortezomib treatment, autophagy assay, NFκB nuclear translocation assay, antioxidant treatment, furosemide inhibition, xenograft tumor model\",\n      \"journal\": \"Molecular cancer therapeutics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple assays including in vivo xenograft, pharmacological dissection, single lab\",\n      \"pmids\": [\"25837675\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"MAP17 is a necessary activator of SGLT2 (SLC5A2): co-expression of MAP17 with SGLT2 in Xenopus oocytes increases SGLT2 activity by two orders of magnitude, and significant stimulation also occurs in opossum kidney cells co-transfected with SGLT2 and MAP17. MAP17 does not change the quantity of SGLT2 protein at the cell surface. A patient with familial renal glucosuria without SGLT2 mutations was found to carry a homozygous splicing mutation in PDZK1IP1 (c.176+1G>A).\",\n      \"method\": \"Expression cloning in Xenopus oocytes, glucose transport assay, co-transfection in opossum kidney cells, cell surface SGLT2 quantification, genetic analysis of patient cohort\",\n      \"journal\": \"Journal of the American Society of Nephrology : JASN\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — functional reconstitution in two heterologous systems (oocytes and mammalian cells), corroborated by human genetic evidence, multiple orthogonal methods\",\n      \"pmids\": [\"27288013\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"MAP17 (PDZK1IP1) interacts with NUMB through its PDZ-binding domain, sequestering NUMB and thereby activating the Notch signaling pathway. This leads to increased stem cell factor expression and expansion of cancer stem-like cells. MAP17 downregulation in tumor cell lines reduces Notch pathway activation and stemness. MAP17 levels directly correlate with tumorsphere formation capability in PDX models.\",\n      \"method\": \"Co-immunoprecipitation, PDZ-binding domain interaction studies, Notch pathway reporter assays, MAP17 overexpression/knockdown in cell lines, tumorsphere formation assay, PDX models\",\n      \"journal\": \"Clinical cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal binding assays, loss/gain-of-function experiments, in vivo PDX validation, multiple orthogonal methods in single study\",\n      \"pmids\": [\"28153862\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"MAP17 expression directly regulates NFAT2 and IL-6 activation and induces differentiation of monocytes to dendritic cells, suggesting a causal role for MAP17 in inflammation.\",\n      \"method\": \"MAP17 overexpression experiments, NFAT2 and IL-6 reporter/activation assays, monocyte differentiation assay\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, limited methodological details in abstract\",\n      \"pmids\": [\"29228712\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"MAP17 colocalizes and co-immunoprecipitates with SGLT2 in HEK293T cells co-expressing V5-tagged SGLT2 and HA-tagged MAP17. In human kidney sections, both proteins overlap at the apical surface of tubular epithelia.\",\n      \"method\": \"Co-immunoprecipitation, colocalization by immunofluorescence in HEK293T cells, immunohistochemistry in human kidney sections\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP with colocalization, corroborating prior functional data, single lab\",\n      \"pmids\": [\"30156268\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PDZK1IP1 (MAP17) interacts with Smad4 protein. PDZK1IP1 inhibits both TGF-β and BMP signaling pathways without affecting R-Smad phosphorylation, instead interfering with R-Smad/Smad4 complex formation and retaining Smad4 in the cytoplasm. The middle region of PDZK1IP1 (Phe40–Ala49) is required for Smad4-regulating activity. PDZK1IP1 knockdown enhances TGF-β target gene expression; overexpression suppresses TGF-β-induced reporter activity, cell migration, and cell growth inhibition, and decreases tumor size in a xenograft model.\",\n      \"method\": \"Co-immunoprecipitation, PDZK1IP1 deletion/variant mutagenesis, R-Smad phosphorylation assays, Smad complex formation assay, cytoplasmic/nuclear fractionation, TGF-β reporter assay, siRNA knockdown, cell migration assay, xenograft tumor model\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods including Co-IP, domain mutagenesis, fractionation, loss/gain-of-function with pathway and in vivo readouts, single lab\",\n      \"pmids\": [\"30718277\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MAP17 increases exosome production in breast cancer tumor cells, and MAP17 protein is released as cargo in exosomes. Exosomal MAP17 transfer to recipient cells increases EMT. An antibody against MAP17 in conditioned media reduces EMT and stemness alterations in recipient cells. MAP17 expression is regulated by demethylation-induced miRNA changes dependent on Notch pathway activation.\",\n      \"method\": \"Exosome isolation, Western blot for MAP17 in exosomes, conditioned media transfer experiments, EMT and stemness assays, antibody blocking experiment, methylation analysis\",\n      \"journal\": \"Oncogenesis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — exosome cargo identification with functional transfer and antibody blocking, single lab\",\n      \"pmids\": [\"33106480\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"MAP17 expression is hypoxia-dependent in HCC. MAP17 knockdown reduces glucose uptake, lactate release, extracellular acidification rate, and glycolytic gene expression. Ectopic expression of wild-type MAP17, but not a PDZ-binding domain mutant (MAP17-PDZm), increases tumor glycolysis. Mechanistically, MAP17 increases ROS, which activates AKT and HIF1α downstream effectors to enhance the Warburg effect. RNA sequencing after MAP17 knockdown reveals transcriptional changes in ROS metabolic processes.\",\n      \"method\": \"Gain/loss-of-function studies, PDZ-binding domain mutagenesis, Seahorse metabolic assay, ROS measurement, co-immunoprecipitation, immunofluorescence, Western blotting, RNA sequencing, xenograft tumor model\",\n      \"journal\": \"Journal of experimental & clinical cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — PDZ domain mutagenesis with mechanistic pathway dissection (ROS→AKT/HIF1α), multiple orthogonal methods including in vivo xenograft\",\n      \"pmids\": [\"33832535\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"FXR1 negatively regulates PDZK1IP1 mRNA by promoting its degradation via direct interaction with the 3'UTR of PDZK1IP1. PDZK1IP1 overexpression inhibits the tumor-promotive phenotype in FXR1-overexpressed esophageal cancer cells.\",\n      \"method\": \"RNA-binding protein immunoprecipitation, mRNA stability assay, 3'UTR interaction analysis, PDZK1IP1 overexpression rescue experiments, xenograft tumor model\",\n      \"journal\": \"Biology direct\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct 3'UTR interaction with mRNA stability measurement and functional rescue, single lab\",\n      \"pmids\": [\"39511680\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Fenofibrate binds tightly to PDZK1IP1 protein (assessed by molecular docking), inhibits its hepatic expression in NIAAA model mice independently of PPARα signaling, and reduces lipid deposition, oxidative stress and inflammation.\",\n      \"method\": \"Molecular docking, Western blot in mouse liver, PPARα gene silencing, NIAAA alcoholic liver disease mouse model\",\n      \"journal\": \"Life sciences\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — molecular docking for binding (computational) with in vivo expression readout only; mechanism primarily inferred rather than reconstituted\",\n      \"pmids\": [\"38042280\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"MAP17 up-regulation in kidneys of diabetic mice is observed with combined empagliflozin (SGLT2i) and ramipril (RAS blocker) treatment, suggesting MAP17 acts as a scaffolding protein placing SGLT2 and NHE3 together in proximal tubular cells.\",\n      \"method\": \"High-throughput proteomic analysis by TMT-labeled mass spectrometry, Western blot validation in db/db diabetic mouse kidneys\",\n      \"journal\": \"Clinical science\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — proteomic screen with Western blot validation, mechanistic interpretation is inferential rather than experimentally proven in this study\",\n      \"pmids\": [\"36524468\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"miR-455-5p directly suppresses PDZK1IP1 (MAP17) expression by targeting it post-transcriptionally. PDZK1IP1 knockdown promotes migration, metastasis, EMT, and increases TGF-β signaling in OSCC cells.\",\n      \"method\": \"Dual-luciferase reporter assay, qRT-PCR, wound-healing assay, transwell invasion assay, in vivo metastasis assay, nuclear/cytoplasmic fractionation, Western blot\",\n      \"journal\": \"Journal of experimental & clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — dual-luciferase confirms miR-455-5p→PDZK1IP1 targeting, loss-of-function with functional readouts, single lab\",\n      \"pmids\": [\"36737832\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"MAP17 activates the RELA-dependent NF-κB pathway in glioblastoma-initiating cells (GICs), increasing BCL2 expression, which promotes TMZ resistance and tumorigenicity. MAP17 overexpression in GICs increases proliferation, TMZ resistance, and tumorigenicity; knockdown impairs these properties. BCL2 overexpression phenocopies MAP17 overexpression, and BCL2 knockdown impairs TMZ resistance in MAP17-high resistant GICs.\",\n      \"method\": \"Stable overexpression and shRNA knockdown in GICs, gene expression profiling, NF-κB pathway assays, BCL2 overexpression/knockdown, TMZ resistance assays, tumorigenicity assays\",\n      \"journal\": \"Cancer science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis via gain/loss-of-function for MAP17-NF-κB-BCL2 pathway, single lab\",\n      \"pmids\": [\"42043964\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"In rats with congestive heart failure (CHF), renal sympathetic nerve activity activates the ERK/NF-κB pathway, which increases SGLT2, MAP17, and PDZK1 expression and their translocation to the luminal membrane. Renal denervation mitigates enhanced expression of the SGLT2-MAP17-PDZK1 complex. Norepinephrine directly triggers SGLT2-MAP17-PDZK1 upregulation via ERK/NF-κB in human proximal tubular cells.\",\n      \"method\": \"Coronary artery ligation CHF rat model, bilateral renal denervation, Western blot, immunohistochemistry, norepinephrine treatment of human proximal tubular cells\",\n      \"journal\": \"Hypertension\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo denervation model with in vitro mechanistic confirmation via norepinephrine treatment; single lab\",\n      \"pmids\": [\"41549941\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SGLT2 is enriched within proximal tubular microvilli and partially colocalizes with its co-factor PDZK1IP1 (MAP17) at this subcellular location, as shown using knockout-validated antibodies in rodent and human kidney tissue.\",\n      \"method\": \"Immunohistochemistry with SGLT2-knockout rodent negative controls, subcellular colocalization analysis\",\n      \"journal\": \"bioRxiv (preprint)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — knockout-validated antibody with colocalization, rigorous negative controls, single preprint study\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"PDZK1IP1/MAP17 is a small (17 kDa), non-glycosylated, dual-pass membrane protein that acts as an obligate accessory/scaffolding unit for the renal Na⁺-glucose cotransporter SGLT2 (increasing its activity ~100-fold), anchors PDZK1 to the apical membrane of proximal tubular cells, forms a NaPi-IIa/PDZK1/MAP17 complex, regulates NaPi-IIa internalization via NHERF3/4 interaction in a PKC-dependent manner, promotes tumorigenic signaling through its PDZ-binding domain by increasing ROS to activate PI3K/AKT and HIF1α, activates Notch signaling by sequestering NUMB, suppresses TGF-β signaling by trapping Smad4 in the cytoplasm and blocking R-Smad/Smad4 complex formation, and drives chemoresistance in glioblastoma-initiating cells via NF-κB-dependent BCL2 upregulation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PDZK1IP1 (MAP17/DD96/SPAP) is a small dual-pass membrane protein of the proximal tubule brush border that functions both as an obligate accessory subunit for renal sodium-coupled transporters and as a membrane scaffold whose dysregulation drives oncogenic signaling [#0, #2, #11]. In the kidney it spans the membrane twice with both termini intracellular, homodimerizes through intracellular Cys55, and is a necessary activator of the Na\\u207a-glucose cotransporter SGLT2, increasing its activity by roughly two orders of magnitude without altering surface SGLT2 abundance; a homozygous PDZK1IP1 splicing mutation causes familial renal glucosuria, establishing this transporter-activating role in human physiology [#2, #11, #14]. Through its C-terminal PDZ-binding domain it interacts with the fourth PDZ domain of PDZK1, anchoring PDZK1 to the apical membrane and assembling a PDZK1/NaPi-IIa/MAP17 complex, and engages NHERF3/NHERF4 to drive PKC-dependent internalization of NaPi-IIa toward the trans-Golgi network, thereby regulating phosphate transport [#1, #3, #4]. The same PDZ-binding domain underlies its tumorigenic activity: MAP17 overexpression elevates reactive oxygen species in a manner dependent on Na\\u207a-coupled cotransport, and this ROS signal activates PI3K/AKT and HIF1\\u03b1 to enhance proliferation, apoptosis resistance, and Warburg-type glycolysis, while ROS instead triggers p38\\u03b1-dependent senescence in non-transformed cells [#5, #6, #9, #17]. MAP17 additionally activates Notch signaling by sequestering NUMB to expand cancer stem-like cells, suppresses TGF-\\u03b2 and BMP signaling by binding Smad4 through its central Phe40\\u2013Ala49 region and retaining it in the cytoplasm to block R-Smad/Smad4 complex formation, and confers therapy resistance via NF-\\u03baB-dependent BCL2 upregulation in glioblastoma-initiating cells and suppression of bortezomib-induced cytoprotective autophagy in breast cancer [#12, #15, #22, #10]. Its expression is post-transcriptionally constrained by FXR1 and miR-455-5p [#18, #21].\",\n  \"teleology\": [\n    {\n      \"year\": 1996,\n      \"claim\": \"Established the existence and tissue distribution of MAP17 and the first functional clue that it could restrain epithelial tumor growth, framing the protein as both a kidney brush-border component and a growth modulator.\",\n      \"evidence\": \"Antibody immunolocalization and cDNA transfection with in vitro proliferation and in vivo tumor growth assays in colon carcinoma cells\",\n      \"pmids\": [\"8701988\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No molecular mechanism for growth suppression\", \"No binding partners identified\", \"Contrasts with later pro-tumorigenic findings, suggesting context dependence not resolved here\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Defined MAP17 as a PDZ-domain scaffold partner and a transport-activating membrane protein, answering how it physically couples to the brush-border transport machinery.\",\n      \"evidence\": \"Yeast two-hybrid, in vitro binding, immunofluorescence in OK cells, plus expression cloning in Xenopus oocytes with Cys55 mutagenesis and topology analysis\",\n      \"pmids\": [\"12837682\", \"12812916\", \"12754212\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the endogenous oocyte transporter being stimulated not defined\", \"Mechanism of PDZK1 degradation upon hepatic overexpression unresolved\", \"Direct vs indirect basis of transport stimulation unclear\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Showed MAP17 organizes regulated trafficking of phosphate transport, linking the scaffold to NHERF3/4-dependent, PKC-controlled internalization rather than static anchoring.\",\n      \"evidence\": \"Bacterial and mammalian two-hybrid systems with PKC/dopamine receptor pharmacology and transport assays in OK cells\",\n      \"pmids\": [\"16926447\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo physiological relevance of TGN-directed internalization not tested\", \"Selectivity for NHERF3/4 over NHERF1/2 mechanistically unexplained\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Reframed MAP17 from growth suppressor to oncogenic driver by identifying ROS production through its PDZ-binding domain as the upstream event activating PI3K/AKT and bypassing apoptotic checkpoints.\",\n      \"evidence\": \"Stable transfection in tumor and Rat1a cells with ROS measurement, PDZ-domain mutagenesis, antioxidant rescue, dominant-negative AKT, and nude mouse tumor assays; plus a genetic screen for TNF-induced arrest bypass\",\n      \"pmids\": [\"17548903\", \"17675338\", \"17230460\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Source of MAP17-driven ROS not molecularly defined\", \"How AKT Thr308 phosphorylation occurs independently of PI3K unexplained\", \"Reconciliation with earlier growth-suppressive role incomplete\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Resolved the suppressor/promoter paradox by showing the same ROS signal produces p38\\u03b1-dependent senescence in normal cells but tumorigenic enhancement where p38\\u03b1 signaling is lost, making cellular context the determinant of outcome.\",\n      \"evidence\": \"Gain- and loss-of-function in breast cell lines with ROS, senescence, p38\\u03b1 phosphorylation, and tumor growth assays\",\n      \"pmids\": [\"22266858\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Threshold of p38\\u03b1 activity that switches outcomes not quantified\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Established MAP17 as a necessary activator of SGLT2 and linked PDZK1IP1 loss to human disease, anchoring its physiological transport role in genetics.\",\n      \"evidence\": \"Expression cloning in oocytes and OK cells, surface SGLT2 quantification, and identification of a homozygous PDZK1IP1 splicing mutation in familial renal glucosuria\",\n      \"pmids\": [\"27288013\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of SGLT2 activation without changing surface levels unknown\", \"Whether activation requires homodimerization not tested for SGLT2 specifically\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identified NUMB sequestration as a discrete oncogenic mechanism, explaining how MAP17 activates Notch signaling and expands cancer stem-like cells beyond its ROS activity.\",\n      \"evidence\": \"Co-immunoprecipitation, PDZ-binding domain interaction studies, Notch reporter assays, knockdown, and tumorsphere/PDX models\",\n      \"pmids\": [\"28153862\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry of NUMB sequestration not defined\", \"Crosstalk between NUMB/Notch and ROS/AKT arms unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Defined a Smad4-trapping mechanism mapped to the central Phe40\\u2013Ala49 region, showing MAP17 suppresses TGF-\\u03b2/BMP signaling without altering R-Smad phosphorylation.\",\n      \"evidence\": \"Co-IP, deletion mutagenesis, R-Smad phosphorylation assays, nuclear/cytoplasmic fractionation, reporter assays, and xenograft model\",\n      \"pmids\": [\"30718277\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How a membrane protein retains Smad4 cytoplasmically not structurally explained\", \"Interplay with PDZ-domain-dependent functions not addressed\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Integrated the ROS arm into tumor metabolism, showing MAP17 drives the Warburg effect via ROS-mediated AKT and HIF1\\u03b1 activation in a PDZ-binding-domain-dependent manner.\",\n      \"evidence\": \"Gain/loss-of-function with PDZ-domain mutant, Seahorse metabolic assays, ROS measurement, RNA-seq, and xenograft model in HCC\",\n      \"pmids\": [\"33832535\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct connection between transporter activity and HIF1\\u03b1 stabilization not biochemically dissected\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Placed PDZK1IP1 under post-transcriptional control and extended its scaffolding role to renal stress responses, defining regulatory inputs and an in vivo transporter-complex context.\",\n      \"evidence\": \"RNA-IP and 3'UTR/mRNA stability assays (FXR1), proteomic and Western analyses in diabetic and heart-failure renal models, and molecular docking for fenofibrate\",\n      \"pmids\": [\"39511680\", \"36524468\", \"38042280\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Fenofibrate binding inferred from docking only\", \"MAP17 scaffolding of SGLT2/NHE3 in stressed kidney is interpretive in these studies\", \"Direct vs indirect FXR1 effects on downstream phenotype incomplete\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Added miR-455-5p as a direct repressor and reinforced the TGF-\\u03b2-suppressive role by showing PDZK1IP1 loss promotes EMT and metastasis.\",\n      \"evidence\": \"Dual-luciferase reporter, qRT-PCR, migration/invasion and in vivo metastasis assays, and fractionation in OSCC cells\",\n      \"pmids\": [\"36737832\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Tissue specificity of tumor-suppressive versus oncogenic behavior not reconciled\", \"Single lab\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Defined an NF-\\u03baB/BCL2 axis underlying therapy resistance and tied renal complex regulation to sympathetic ERK/NF-\\u03baB signaling, broadening MAP17's roles in chemoresistance and cardiorenal physiology.\",\n      \"evidence\": \"Overexpression/knockdown with NF-\\u03baB and BCL2 epistasis and TMZ resistance assays in glioblastoma-initiating cells; CHF rat model with renal denervation and norepinephrine treatment of human proximal tubular cells\",\n      \"pmids\": [\"42043964\", \"41549941\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether NF-\\u03baB activation depends on the ROS or scaffolding arm not resolved\", \"Direct molecular link between MAP17 and RELA activation unknown\", \"Single-lab findings\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How a single small membrane protein integrates its transporter-activating scaffolding function with its multiple cytoplasmic signaling effects (NUMB, Smad4, ROS, NF-\\u03baB) at the structural and stoichiometric level remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structure of MAP17 or its complexes\", \"Mechanism linking Na\\u207a-coupled transport to ROS generation undefined\", \"No unified model reconciling growth-suppressive and oncogenic contexts\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 4, 11, 15]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [2, 11, 5]},\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [2, 11]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 1, 11, 14, 24]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [15]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [2, 11, 4]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [12, 15, 22, 17]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [11, 5, 17]}\n    ],\n    \"complexes\": [\n      \"PDZK1/NaPi-IIa/MAP17 complex\",\n      \"SGLT2-MAP17-PDZK1 complex\"\n    ],\n    \"partners\": [\n      \"PDZK1\",\n      \"SLC5A2\",\n      \"NaPi-IIa\",\n      \"NHERF3\",\n      \"NHERF4\",\n      \"NHE3\",\n      \"NUMB\",\n      \"SMAD4\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":6,"faith_total":6,"faith_pct":100.0}}