{"gene":"SH2B2","run_date":"2026-06-10T07:46:31","timeline":{"discoveries":[{"year":2007,"finding":"SH2B2beta, a splice isoform of SH2B2 lacking an SH2 domain, binds to SH2B1 and SH2B2alpha via its dimerization (DD) domain (demonstrated by GST pulldown in vitro and co-immunoprecipitation in intact cells), and markedly attenuates SH2B1-promoted JAK2 activation and subsequent IRS-1 tyrosine phosphorylation, as well as SH2B1- or SH2B2alpha-promoted insulin signaling, acting as an endogenous inhibitor.","method":"GST fusion protein pulldown (in vitro), co-immunoprecipitation in intact cells, functional kinase/phosphorylation assays","journal":"Endocrinology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP plus GST pulldown plus functional kinase assays, single lab but three orthogonal methods","pmids":["17204555"],"is_preprint":false},{"year":2013,"finding":"Deletion of liver SH2B1 in SH2B2 null mice attenuated VLDL secretion, and adult-onset deletion of hepatic SH2B1 (alone) decreased DGAT2 expression and increased ATGL expression, indicating that SH2B1 and SH2B2 together regulate hepatic triglyceride synthesis, lipolysis, and VLDL secretion without affecting insulin sensitivity or glucose metabolism.","method":"Hepatocyte-specific SH2B1 knockout combined with whole-body SH2B2 knockout mice; metabolic phenotyping, gene expression analysis (qRT-PCR/Western blot)","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean genetic KO with defined metabolic phenotype and molecular readouts, single lab","pmids":["24358267"],"is_preprint":false},{"year":2021,"finding":"SH2B2 participates in insulin receptor signaling by being phosphorylated downstream of the activated insulin receptor, initiating activation of G proteins such as TC10 (via the c-Cbl/CAP/TC10 pathway).","method":"Review synthesizing prior experimental work on insulin receptor signaling pathways","journal":"The Journal of clinical investigation","confidence":"Low","confidence_rationale":"Tier 4 / Weak — pathway placement cited from prior work but no new primary experiment described in this abstract","pmids":["33393497"],"is_preprint":false},{"year":2013,"finding":"The SH2 domain of SH2B2 (APS) binds to phosphorylated tyrosines in the insulin receptor activation loop (engaging two phosphotyrosines via a dimeric SH2 domain interaction), providing a docking site for this adaptor protein.","method":"Structural and biochemical characterization reviewed; dimeric SH2 domain engagement of two phosphotyrosines in activation loop described from prior structural studies","journal":"Cold Spring Harbor perspectives in biology","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — structural mechanism described in a review citing prior structural data, single source in this corpus","pmids":["23457259"],"is_preprint":false},{"year":2014,"finding":"SH2B2 (APS) forms homo- or heterodimers with SH2B1 via N-terminal dimerization domains; its SH2 domain binds tyrosyl-phosphorylated proteins including JAK2, insulin receptors, IGF-1 receptors, IRS-1, and IRS-2. Unlike SH2B1, SH2B2 is not required for maintenance of normal energy and glucose homeostasis (SH2B2 knockout mice are metabolically normal).","method":"Genetic knockout mouse studies; biochemical binding assays (co-IP, domain analysis) synthesized from prior work","journal":"World journal of diabetes","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple prior experimental studies synthesized; knockout phenotype established across labs","pmids":["25126397"],"is_preprint":false},{"year":2011,"finding":"SH2B2 (APS) enhances NGF-induced neuronal differentiation in PC12 cells; SH2B3 competes with SH2B2 for TrkA binding to inhibit this effect, as overexpression of the SH2 domain of SH2B3 reduces SH2B1β-TrkA interaction and inhibits NGF-induced neurite outgrowth.","method":"Overexpression studies in PC12 cells, co-immunoprecipitation of TrkA binding, neurite outgrowth assays","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP plus functional cellular assay, replicated across multiple constructs in single lab","pmids":["22028877"],"is_preprint":false},{"year":2009,"finding":"Nuclear translocation of SH2B2 (APS) was not observed, in contrast to SH2B1β which shuttles between plasma membrane and nucleus; SH2B2 lacks nuclear localization/export signal-dependent nucleocytoplasmic shuttling function.","method":"Live imaging and localization studies of SH2B family members in cells; comparison of SH2B1β and SH2B2 subcellular localization","journal":"Molecular endocrinology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct imaging-based localization experiment, negative finding for SH2B2 nuclear translocation confirmed in single study","pmids":["19372237"],"is_preprint":false},{"year":2024,"finding":"In Aps/Sh2b2-deficient mice, GC B cell numbers are reduced after immunization and cell death of Aps−/− GC B cells is enhanced compared to wild-type. IgE-specific production is impaired. Furthermore, Aps deficiency in B cells results in augmented depletion of IgE+ blasts by B cell receptor crosslinking (anti-CD79b), suggesting SH2B2/APS promotes survival of GC B cells and IgE+ plasma cells downstream of BCR signaling.","method":"Genetic knockout mice (Aps−/−), in vivo immunization, flow cytometry for GC B cell frequencies/apoptosis, in vitro B cell culture system with BCR crosslinking","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with multiple cellular readouts and in vitro rescue experiments, single lab","pmids":["39090233"],"is_preprint":false},{"year":2025,"finding":"SH2B2 is downregulated in MPTP-induced mouse PD model and MPP+-treated SH-SY5Y cells; overexpression of SH2B2 reversed MPP+-induced cell viability reduction and apoptosis in SH-SY5Y cells, upregulated tyrosine hydroxylase (TH) expression, downregulated IBA1 levels (neuroinflammation marker), and improved motor function in MPTP mice, indicating a neuroprotective role for SH2B2 in dopaminergic neurons.","method":"In vivo MPTP mouse model with lentiviral SH2B2 overexpression; in vitro MPP+-treated SH-SY5Y cells with OE-SH2B2; behavioral tests, CCK-8 viability assay, flow cytometry (apoptosis), Western blot, IHC","journal":"Neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — loss-of-expression plus overexpression rescue with defined molecular readouts, in vivo and in vitro, but single lab and mechanism not fully resolved","pmids":["41482210"],"is_preprint":false}],"current_model":"SH2B2 (APS) is an adaptor protein with N-terminal dimerization, PH, and SH2 domains that binds phosphotyrosines in the insulin receptor activation loop, JAK2, and other receptor tyrosine kinases to modulate downstream signaling; its alternatively spliced isoform SH2B2beta (lacking the SH2 domain) acts as an endogenous dominant-negative inhibitor by heterodimerizing with SH2B1 and SH2B2alpha; SH2B2 promotes survival of germinal center B cells and IgE production, enhances NGF-induced neuronal differentiation via TrkA, and exerts neuroprotective effects in dopaminergic neurons, while being dispensable for systemic energy and glucose homeostasis but contributing with SH2B1 to hepatic lipid metabolism and VLDL secretion."},"narrative":{"mechanistic_narrative":"SH2B2 (APS) is a cytoplasmic adaptor protein that couples activated receptor and non-receptor tyrosine kinases to downstream signaling through its modular domain architecture: N-terminal dimerization domains mediate homo- and heterodimerization with SH2B1, and an SH2 domain docks onto tyrosyl-phosphorylated targets including JAK2, the insulin and IGF-1 receptors, and IRS-1/IRS-2 [PMID:25126397]. Structurally, the SH2 domain engages two phosphotyrosines in the insulin receptor activation loop via a dimeric interaction, providing a high-avidity docking platform on the activated receptor [PMID:23457259]. An alternatively spliced isoform, SH2B2beta, lacks the SH2 domain and functions as an endogenous dominant-negative inhibitor by heterodimerizing through its dimerization domain with SH2B1 and SH2B2alpha, thereby attenuating SH2B1-promoted JAK2 activation, IRS-1 phosphorylation, and insulin signaling [PMID:17204555]. Despite this role in insulin-receptor signaling, SH2B2 is dispensable for systemic energy and glucose homeostasis, with knockout mice metabolically normal [PMID:25126397], but it acts together with SH2B1 in the liver to regulate triglyceride synthesis, lipolysis, and VLDL secretion [PMID:24358267]. Beyond metabolism, SH2B2 promotes survival of germinal center B cells and IgE+ plasma cells downstream of BCR signaling [PMID:39090233], enhances NGF-induced neuronal differentiation via TrkA [PMID:22028877], and exerts neuroprotective, anti-apoptotic effects in dopaminergic neurons in models of Parkinsonian injury [PMID:41482210]. Unlike SH2B1, SH2B2 does not undergo nucleocytoplasmic shuttling [PMID:19372237].","teleology":[{"year":2007,"claim":"Established that a splice isoform of SH2B2 acts as a built-in negative regulator of the SH2B adaptor family, defining an intrinsic brake on JAK2 and insulin signaling.","evidence":"GST pulldown, reciprocal co-IP, and functional kinase/phosphorylation assays in cells","pmids":["17204555"],"confidence":"High","gaps":["Physiological contexts where the beta isoform predominates were not defined","Quantitative stoichiometry of heterodimers in vivo not established"]},{"year":2009,"claim":"Distinguished SH2B2 from its paralog SH2B1 by showing it lacks nucleocytoplasmic shuttling, constraining where SH2B2 can act in the cell.","evidence":"Live imaging and subcellular localization comparison of SH2B family members","pmids":["19372237"],"confidence":"Medium","gaps":["Functional consequence of restricted localization not tested","No mapping of the determinants that distinguish the two paralogs"]},{"year":2011,"claim":"Placed SH2B2 in neurotrophin signaling by showing it enhances NGF-induced differentiation through TrkA, with SH2B3 acting as a competitive antagonist for receptor binding.","evidence":"Overexpression, co-IP of TrkA binding, and neurite outgrowth assays in PC12 cells","pmids":["22028877"],"confidence":"Medium","gaps":["Endogenous requirement for SH2B2 in neuronal differentiation not tested by loss-of-function","Downstream effectors of SH2B2-TrkA coupling unresolved"]},{"year":2013,"claim":"Defined the structural basis of SH2B2 recruitment, showing its dimeric SH2 domain engages two phosphotyrosines in the insulin receptor activation loop.","evidence":"Structural and biochemical characterization synthesized in review","pmids":["23457259"],"confidence":"Medium","gaps":["Affinity and selectivity for distinct receptor phosphosites not quantified in this corpus","Functional output of activation-loop docking not directly linked"]},{"year":2013,"claim":"Demonstrated a non-redundant hepatic role: SH2B2 acts with SH2B1 to control triglyceride synthesis, lipolysis, and VLDL secretion, dissociating this lipid function from insulin/glucose control.","evidence":"Hepatocyte-specific SH2B1 knockout combined with whole-body SH2B2 knockout mice with metabolic phenotyping and gene expression analysis","pmids":["24358267"],"confidence":"Medium","gaps":["Direct molecular link between SH2B2 and DGAT2/ATGL regulation not established","SH2B2-specific contribution distinct from SH2B1 not isolated"]},{"year":2014,"claim":"Consolidated SH2B2 domain function and binding partners while establishing that, unlike SH2B1, SH2B2 is dispensable for systemic energy and glucose homeostasis.","evidence":"Knockout mouse phenotyping and biochemical binding assays synthesized from prior work","pmids":["25126397"],"confidence":"Medium","gaps":["Compensation by paralogs in knockout mice not excluded","Tissue-specific requirements masked by whole-body phenotyping"]},{"year":2024,"claim":"Revealed an immune role for SH2B2 as a survival factor for germinal center B cells and IgE+ plasma cells downstream of BCR signaling.","evidence":"Aps-deficient mice with in vivo immunization, flow cytometry for GC B cell frequency/apoptosis, and in vitro BCR crosslinking","pmids":["39090233"],"confidence":"Medium","gaps":["Molecular pathway by which SH2B2 promotes B cell survival not defined","Direct phosphotyrosine partners in BCR signaling not identified"]},{"year":2025,"claim":"Identified a neuroprotective, anti-apoptotic function for SH2B2 in dopaminergic neurons under Parkinsonian insult.","evidence":"MPTP mouse and MPP+-treated SH-SY5Y models with SH2B2 overexpression rescue, behavioral, viability, apoptosis, and marker readouts","pmids":["41482210"],"confidence":"Medium","gaps":["Mechanism connecting SH2B2 to TH and neuroinflammation markers not resolved","Endogenous loss-of-function effect in dopaminergic neurons not tested","Single lab"]},{"year":null,"claim":"How SH2B2's adaptor activity at specific receptors is mechanistically translated into its divergent tissue roles (B cell survival, neuronal protection, hepatic lipid handling) remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying downstream effector connecting receptor docking to cell-type-specific outcomes","Roles of dimerization with SH2B1 in non-metabolic tissues not tested","No structural data on full-length SH2B2 in this corpus"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,4]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[6]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,3,4]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[1]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[7]}],"complexes":[],"partners":["SH2B1","JAK2","IRS1","IRS2","TRKA","SH2B3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O14492","full_name":"SH2B adapter protein 2","aliases":["Adapter protein with pleckstrin homology and Src homology 2 domains","SH2 and PH domain-containing adapter protein APS"],"length_aa":632,"mass_kda":67.7,"function":"Adapter protein for several members of the tyrosine kinase receptor family. Involved in multiple signaling pathways. May be involved in coupling from immunoreceptor to Ras signaling. Acts as a negative regulator of cytokine signaling in collaboration with CBL. Binds to EPOR and suppresses EPO-induced STAT5 activation, possibly through a masking effect on STAT5 docking sites in EPOR. Suppresses PDGF-induced mitogenesis. May induce cytoskeletal reorganization via interaction with VAV3","subcellular_location":"Cytoplasm; Cell membrane","url":"https://www.uniprot.org/uniprotkb/O14492/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SH2B2","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":74,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SH2B2","total_profiled":1310},"omim":[{"mim_id":"605300","title":"SH2B ADAPTOR PROTEIN 2; SH2B2","url":"https://www.omim.org/entry/605300"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"skeletal muscle","ntpm":33.1}],"url":"https://www.proteinatlas.org/search/SH2B2"},"hgnc":{"alias_symbol":["APS"],"prev_symbol":[]},"alphafold":{"accession":"O14492","domains":[{"cath_id":"2.30.29.30","chopping":"195-207_217-307","consensus_level":"high","plddt":88.4023,"start":195,"end":307},{"cath_id":"3.30.505.10","chopping":"413-516","consensus_level":"high","plddt":88.9144,"start":413,"end":516}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O14492","model_url":"https://alphafold.ebi.ac.uk/files/AF-O14492-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O14492-F1-predicted_aligned_error_v6.png","plddt_mean":62.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SH2B2","jax_strain_url":"https://www.jax.org/strain/search?query=SH2B2"},"sequence":{"accession":"O14492","fasta_url":"https://rest.uniprot.org/uniprotkb/O14492.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O14492/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O14492"}},"corpus_meta":[{"pmid":"33393497","id":"PMC_33393497","title":"Insulin 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shuttling of the adapter protein SH2B1beta (SH2-Bbeta) is required for nerve growth factor (NGF)-dependent neurite outgrowth and enhancement of expression of a subset of NGF-responsive genes.","date":"2009","source":"Molecular endocrinology (Baltimore, Md.)","url":"https://pubmed.ncbi.nlm.nih.gov/19372237","citation_count":27,"is_preprint":false},{"pmid":"22028877","id":"PMC_22028877","title":"The adaptor protein SH2B3 (Lnk) negatively regulates neurite outgrowth of PC12 cells and cortical neurons.","date":"2011","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22028877","citation_count":25,"is_preprint":false},{"pmid":"24358267","id":"PMC_24358267","title":"Hepatic SH2B1 and SH2B2 regulate liver lipid metabolism and VLDL secretion in mice.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24358267","citation_count":24,"is_preprint":false},{"pmid":"22873350","id":"PMC_22873350","title":"Preeclampsia: a bioinformatics approach through protein-protein 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transcription factor oncogenes and identifying small-molecular anticancer drugs.","date":"2021","source":"Chemical biology & drug design","url":"https://pubmed.ncbi.nlm.nih.gov/34757684","citation_count":5,"is_preprint":false},{"pmid":"39821900","id":"PMC_39821900","title":"Effects of dietary oregano essential oil supplementation on carcass traits, muscle fiber structure, oxidative stability, meat quality, and regulatory mechanisms in Holstein steers.","date":"2025","source":"Journal of the science of food and agriculture","url":"https://pubmed.ncbi.nlm.nih.gov/39821900","citation_count":4,"is_preprint":false},{"pmid":"39090233","id":"PMC_39090233","title":"Control of germinal center B cell survival and IgE production by an adaptor molecule containing PH and SH2 domains, Aps/Sh2b2.","date":"2024","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/39090233","citation_count":1,"is_preprint":false},{"pmid":"41482210","id":"PMC_41482210","title":"Investigations on the effects of SH2B2 on Parkinson's disease based on its in vivo and in vitro neurotoxic model.","date":"2025","source":"Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/41482210","citation_count":1,"is_preprint":false},{"pmid":"19122374","id":"PMC_19122374","title":"[Sh2b3/Lnk family adaptor proteins in the regulation of lymphohematopoiesis].","date":"2008","source":"Nihon Rinsho Men'eki Gakkai kaishi = Japanese journal of clinical immunology","url":"https://pubmed.ncbi.nlm.nih.gov/19122374","citation_count":1,"is_preprint":false},{"pmid":"41140666","id":"PMC_41140666","title":"Multi-omics integration to identify immune-associated biomarkers and potential therapeutics in periodontitis.","date":"2025","source":"Frontiers in medicine","url":"https://pubmed.ncbi.nlm.nih.gov/41140666","citation_count":1,"is_preprint":false},{"pmid":"10524764","id":"PMC_10524764","title":"The genomic and sequence analysis of rat histone H2B genes.","date":"1998","source":"DNA sequence : the journal of DNA 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Cells","date":"2025-01-18","source":"bioRxiv","url":"https://doi.org/10.1101/2025.01.16.633312","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":14909,"output_tokens":2417,"usd":0.040491,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9563,"output_tokens":2958,"usd":0.060882,"stage2_stop_reason":"end_turn"},"total_usd":0.101373,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2007,\n      \"finding\": \"SH2B2beta, a splice isoform of SH2B2 lacking an SH2 domain, binds to SH2B1 and SH2B2alpha via its dimerization (DD) domain (demonstrated by GST pulldown in vitro and co-immunoprecipitation in intact cells), and markedly attenuates SH2B1-promoted JAK2 activation and subsequent IRS-1 tyrosine phosphorylation, as well as SH2B1- or SH2B2alpha-promoted insulin signaling, acting as an endogenous inhibitor.\",\n      \"method\": \"GST fusion protein pulldown (in vitro), co-immunoprecipitation in intact cells, functional kinase/phosphorylation assays\",\n      \"journal\": \"Endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP plus GST pulldown plus functional kinase assays, single lab but three orthogonal methods\",\n      \"pmids\": [\"17204555\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Deletion of liver SH2B1 in SH2B2 null mice attenuated VLDL secretion, and adult-onset deletion of hepatic SH2B1 (alone) decreased DGAT2 expression and increased ATGL expression, indicating that SH2B1 and SH2B2 together regulate hepatic triglyceride synthesis, lipolysis, and VLDL secretion without affecting insulin sensitivity or glucose metabolism.\",\n      \"method\": \"Hepatocyte-specific SH2B1 knockout combined with whole-body SH2B2 knockout mice; metabolic phenotyping, gene expression analysis (qRT-PCR/Western blot)\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic KO with defined metabolic phenotype and molecular readouts, single lab\",\n      \"pmids\": [\"24358267\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"SH2B2 participates in insulin receptor signaling by being phosphorylated downstream of the activated insulin receptor, initiating activation of G proteins such as TC10 (via the c-Cbl/CAP/TC10 pathway).\",\n      \"method\": \"Review synthesizing prior experimental work on insulin receptor signaling pathways\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — pathway placement cited from prior work but no new primary experiment described in this abstract\",\n      \"pmids\": [\"33393497\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"The SH2 domain of SH2B2 (APS) binds to phosphorylated tyrosines in the insulin receptor activation loop (engaging two phosphotyrosines via a dimeric SH2 domain interaction), providing a docking site for this adaptor protein.\",\n      \"method\": \"Structural and biochemical characterization reviewed; dimeric SH2 domain engagement of two phosphotyrosines in activation loop described from prior structural studies\",\n      \"journal\": \"Cold Spring Harbor perspectives in biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — structural mechanism described in a review citing prior structural data, single source in this corpus\",\n      \"pmids\": [\"23457259\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"SH2B2 (APS) forms homo- or heterodimers with SH2B1 via N-terminal dimerization domains; its SH2 domain binds tyrosyl-phosphorylated proteins including JAK2, insulin receptors, IGF-1 receptors, IRS-1, and IRS-2. Unlike SH2B1, SH2B2 is not required for maintenance of normal energy and glucose homeostasis (SH2B2 knockout mice are metabolically normal).\",\n      \"method\": \"Genetic knockout mouse studies; biochemical binding assays (co-IP, domain analysis) synthesized from prior work\",\n      \"journal\": \"World journal of diabetes\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple prior experimental studies synthesized; knockout phenotype established across labs\",\n      \"pmids\": [\"25126397\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"SH2B2 (APS) enhances NGF-induced neuronal differentiation in PC12 cells; SH2B3 competes with SH2B2 for TrkA binding to inhibit this effect, as overexpression of the SH2 domain of SH2B3 reduces SH2B1β-TrkA interaction and inhibits NGF-induced neurite outgrowth.\",\n      \"method\": \"Overexpression studies in PC12 cells, co-immunoprecipitation of TrkA binding, neurite outgrowth assays\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP plus functional cellular assay, replicated across multiple constructs in single lab\",\n      \"pmids\": [\"22028877\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Nuclear translocation of SH2B2 (APS) was not observed, in contrast to SH2B1β which shuttles between plasma membrane and nucleus; SH2B2 lacks nuclear localization/export signal-dependent nucleocytoplasmic shuttling function.\",\n      \"method\": \"Live imaging and localization studies of SH2B family members in cells; comparison of SH2B1β and SH2B2 subcellular localization\",\n      \"journal\": \"Molecular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct imaging-based localization experiment, negative finding for SH2B2 nuclear translocation confirmed in single study\",\n      \"pmids\": [\"19372237\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In Aps/Sh2b2-deficient mice, GC B cell numbers are reduced after immunization and cell death of Aps−/− GC B cells is enhanced compared to wild-type. IgE-specific production is impaired. Furthermore, Aps deficiency in B cells results in augmented depletion of IgE+ blasts by B cell receptor crosslinking (anti-CD79b), suggesting SH2B2/APS promotes survival of GC B cells and IgE+ plasma cells downstream of BCR signaling.\",\n      \"method\": \"Genetic knockout mice (Aps−/−), in vivo immunization, flow cytometry for GC B cell frequencies/apoptosis, in vitro B cell culture system with BCR crosslinking\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with multiple cellular readouts and in vitro rescue experiments, single lab\",\n      \"pmids\": [\"39090233\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SH2B2 is downregulated in MPTP-induced mouse PD model and MPP+-treated SH-SY5Y cells; overexpression of SH2B2 reversed MPP+-induced cell viability reduction and apoptosis in SH-SY5Y cells, upregulated tyrosine hydroxylase (TH) expression, downregulated IBA1 levels (neuroinflammation marker), and improved motor function in MPTP mice, indicating a neuroprotective role for SH2B2 in dopaminergic neurons.\",\n      \"method\": \"In vivo MPTP mouse model with lentiviral SH2B2 overexpression; in vitro MPP+-treated SH-SY5Y cells with OE-SH2B2; behavioral tests, CCK-8 viability assay, flow cytometry (apoptosis), Western blot, IHC\",\n      \"journal\": \"Neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — loss-of-expression plus overexpression rescue with defined molecular readouts, in vivo and in vitro, but single lab and mechanism not fully resolved\",\n      \"pmids\": [\"41482210\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SH2B2 (APS) is an adaptor protein with N-terminal dimerization, PH, and SH2 domains that binds phosphotyrosines in the insulin receptor activation loop, JAK2, and other receptor tyrosine kinases to modulate downstream signaling; its alternatively spliced isoform SH2B2beta (lacking the SH2 domain) acts as an endogenous dominant-negative inhibitor by heterodimerizing with SH2B1 and SH2B2alpha; SH2B2 promotes survival of germinal center B cells and IgE production, enhances NGF-induced neuronal differentiation via TrkA, and exerts neuroprotective effects in dopaminergic neurons, while being dispensable for systemic energy and glucose homeostasis but contributing with SH2B1 to hepatic lipid metabolism and VLDL secretion.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SH2B2 (APS) is a cytoplasmic adaptor protein that couples activated receptor and non-receptor tyrosine kinases to downstream signaling through its modular domain architecture: N-terminal dimerization domains mediate homo- and heterodimerization with SH2B1, and an SH2 domain docks onto tyrosyl-phosphorylated targets including JAK2, the insulin and IGF-1 receptors, and IRS-1/IRS-2 [#4]. Structurally, the SH2 domain engages two phosphotyrosines in the insulin receptor activation loop via a dimeric interaction, providing a high-avidity docking platform on the activated receptor [#3]. An alternatively spliced isoform, SH2B2beta, lacks the SH2 domain and functions as an endogenous dominant-negative inhibitor by heterodimerizing through its dimerization domain with SH2B1 and SH2B2alpha, thereby attenuating SH2B1-promoted JAK2 activation, IRS-1 phosphorylation, and insulin signaling [#0]. Despite this role in insulin-receptor signaling, SH2B2 is dispensable for systemic energy and glucose homeostasis, with knockout mice metabolically normal [#4], but it acts together with SH2B1 in the liver to regulate triglyceride synthesis, lipolysis, and VLDL secretion [#1]. Beyond metabolism, SH2B2 promotes survival of germinal center B cells and IgE+ plasma cells downstream of BCR signaling [#7], enhances NGF-induced neuronal differentiation via TrkA [#5], and exerts neuroprotective, anti-apoptotic effects in dopaminergic neurons in models of Parkinsonian injury [#8]. Unlike SH2B1, SH2B2 does not undergo nucleocytoplasmic shuttling [#6].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Established that a splice isoform of SH2B2 acts as a built-in negative regulator of the SH2B adaptor family, defining an intrinsic brake on JAK2 and insulin signaling.\",\n      \"evidence\": \"GST pulldown, reciprocal co-IP, and functional kinase/phosphorylation assays in cells\",\n      \"pmids\": [\"17204555\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological contexts where the beta isoform predominates were not defined\", \"Quantitative stoichiometry of heterodimers in vivo not established\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Distinguished SH2B2 from its paralog SH2B1 by showing it lacks nucleocytoplasmic shuttling, constraining where SH2B2 can act in the cell.\",\n      \"evidence\": \"Live imaging and subcellular localization comparison of SH2B family members\",\n      \"pmids\": [\"19372237\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of restricted localization not tested\", \"No mapping of the determinants that distinguish the two paralogs\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Placed SH2B2 in neurotrophin signaling by showing it enhances NGF-induced differentiation through TrkA, with SH2B3 acting as a competitive antagonist for receptor binding.\",\n      \"evidence\": \"Overexpression, co-IP of TrkA binding, and neurite outgrowth assays in PC12 cells\",\n      \"pmids\": [\"22028877\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Endogenous requirement for SH2B2 in neuronal differentiation not tested by loss-of-function\", \"Downstream effectors of SH2B2-TrkA coupling unresolved\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Defined the structural basis of SH2B2 recruitment, showing its dimeric SH2 domain engages two phosphotyrosines in the insulin receptor activation loop.\",\n      \"evidence\": \"Structural and biochemical characterization synthesized in review\",\n      \"pmids\": [\"23457259\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Affinity and selectivity for distinct receptor phosphosites not quantified in this corpus\", \"Functional output of activation-loop docking not directly linked\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Demonstrated a non-redundant hepatic role: SH2B2 acts with SH2B1 to control triglyceride synthesis, lipolysis, and VLDL secretion, dissociating this lipid function from insulin/glucose control.\",\n      \"evidence\": \"Hepatocyte-specific SH2B1 knockout combined with whole-body SH2B2 knockout mice with metabolic phenotyping and gene expression analysis\",\n      \"pmids\": [\"24358267\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular link between SH2B2 and DGAT2/ATGL regulation not established\", \"SH2B2-specific contribution distinct from SH2B1 not isolated\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Consolidated SH2B2 domain function and binding partners while establishing that, unlike SH2B1, SH2B2 is dispensable for systemic energy and glucose homeostasis.\",\n      \"evidence\": \"Knockout mouse phenotyping and biochemical binding assays synthesized from prior work\",\n      \"pmids\": [\"25126397\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Compensation by paralogs in knockout mice not excluded\", \"Tissue-specific requirements masked by whole-body phenotyping\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Revealed an immune role for SH2B2 as a survival factor for germinal center B cells and IgE+ plasma cells downstream of BCR signaling.\",\n      \"evidence\": \"Aps-deficient mice with in vivo immunization, flow cytometry for GC B cell frequency/apoptosis, and in vitro BCR crosslinking\",\n      \"pmids\": [\"39090233\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular pathway by which SH2B2 promotes B cell survival not defined\", \"Direct phosphotyrosine partners in BCR signaling not identified\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified a neuroprotective, anti-apoptotic function for SH2B2 in dopaminergic neurons under Parkinsonian insult.\",\n      \"evidence\": \"MPTP mouse and MPP+-treated SH-SY5Y models with SH2B2 overexpression rescue, behavioral, viability, apoptosis, and marker readouts\",\n      \"pmids\": [\"41482210\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism connecting SH2B2 to TH and neuroinflammation markers not resolved\", \"Endogenous loss-of-function effect in dopaminergic neurons not tested\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How SH2B2's adaptor activity at specific receptors is mechanistically translated into its divergent tissue roles (B cell survival, neuronal protection, hepatic lipid handling) remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying downstream effector connecting receptor docking to cell-type-specific outcomes\", \"Roles of dimerization with SH2B1 in non-metabolic tissues not tested\", \"No structural data on full-length SH2B2 in this corpus\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 4]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 3, 4]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [7]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"SH2B1\", \"JAK2\", \"IRS1\", \"IRS2\", \"TrkA\", \"SH2B3\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":6,"faith_pct":83.33333333333333}}