Affinage

Showing ICA1 — ICA69 is a alias.

ICA1

Islet cell autoantigen 1 · UniProt Q05084

Length
483 aa
Mass
54.6 kDa
Annotated
2026-06-10
32 papers in source corpus 15 papers cited in narrative 15 extracted findings
Cross-family judge faithfulness: 6/7 claims corpus-supported (86%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

ICA1 encodes ICA69, a conserved BAR-domain cytosolic protein that links membrane deformation to regulated secretion in both neuroendocrine and neuronal cells (PMID:8326004, PMID:11029035). A subpopulation associates with synaptic vesicles and synaptic-like microvesicles, and its loss in the C. elegans ortholog RIC-19 impairs neurotransmitter secretion (PMID:11029035). Mechanistically, ICA69 acts as a GTP-dependent effector of Rab2: Rab2 recruits it to membranes and positions it within ER-Golgi COPI vesicle transport, where it is required for anterograde delivery of secretory granule precursors (pro-ICA512, chromogranin A) and stimulated insulin secretion (PMID:18187231). Its N-BAR domain binds and deforms liposomes and induces filopodia, and genetic epistasis places it in a Rab2→ICA69→PICK1 pathway controlling synaptic architecture (PMID:28455372). In neurons, ICA69 is the major brain partner of PICK1, forming heteromeric BAR complexes whose balance against PICK1 homomers governs AMPA receptor clustering, surface expression, and trafficking (PMID:18032668); through this PICK1 axis it stabilizes PICK1 protein and is selectively required for NMDAR-dependent LTP and for spatial and associative memory (PMID:37251649). Independently, thymic ICA69 expression — set by AIRE acting on the Ica1 promoter — drives central negative selection of ICA69-reactive T cells, and its loss causes spontaneous multi-organ autoimmunity, establishing ICA69 as a tolerance-controlling autoantigen (PMID:25088457, PMID:22447927). ICA69 also promotes STING-driven ferroptosis in cardiomyocytes during endotoxemia (PMID:35397620).

Mechanistic history

Synthesis pass · year-by-year structured walk · 12 steps
  1. 1993 Medium

    Established that ICA1 encodes a discrete 69 kDa protein (ICA69) and defined its tissue distribution, providing the molecular entity to study in beta cells and brain.

    Evidence cDNA library screening with Northern, Western, and SDS-PAGE characterization

    PMID:8326004

    Open questions at the time
    • No function assigned at this stage
    • Subcellular localization and binding partners unknown
  2. 2000 High

    Showed ICA69 is a conserved membrane-associated regulator of neuroendocrine secretion, moving it from an antigen to a vesicle-trafficking protein.

    Evidence Subcellular fractionation and immunostaining in mouse, plus C. elegans ric-19 deletion (aldicarb resistance) with transgenic rescue

    PMID:11029035

    Open questions at the time
    • Molecular partners and the membrane-binding mechanism not yet defined
    • Direct biochemical role in vesicle budding unresolved
  3. 2007 High

    Identified PICK1 as the dominant brain partner and defined ICA69-PICK1 heteromeric BAR complexes as a switch controlling AMPA receptor trafficking.

    Evidence Reciprocal Co-IP from brain, liposome binding, and neuronal overexpression with surface AMPAR quantification

    PMID:18032668

    Open questions at the time
    • Effect shown by overexpression rather than endogenous loss-of-function
    • In vivo synaptic consequence not yet tested
  4. 2008 High

    Defined ICA69 as a GTP-dependent Rab2 effector required for ER-Golgi anterograde transport and insulin secretion, giving its trafficking role a molecular mechanism.

    Evidence GTP-dependent Co-IP, membrane recruitment, and pulse-chase secretory granule trafficking plus insulin secretion assays in INS-1 cells

    PMID:18187231

    Open questions at the time
    • Direct demonstration of BAR-mediated membrane curvature in this pathway not shown
    • Relationship between Rab2 and PICK1 functions unaddressed here
  5. 2017 High

    Ordered the pathway genetically (Rab2→ICA69→PICK1) and demonstrated direct N-BAR membrane deformation, unifying the trafficking and synaptic roles.

    Evidence Drosophila RNAi/genetic loss-of-function, liposome deformation, filopodia induction, and epistasis at the NMJ

    PMID:28455372

    Open questions at the time
    • Structural basis of heteromeric BAR assembly not resolved
    • Conservation of epistasis order in mammals not directly tested
  6. 2013 Medium

    Mapped the C-terminal domain as the PICK1-interacting/PKCα-regulating module and linked ICA69 to cerebellar LTD induction.

    Evidence Domain-deletion Co-IP, PICK1-PKCα trafficking imaging, and protein infusion with LTD electrophysiology in Purkinje cells

    PMID:24358315

    Open questions at the time
    • Acute infusion/overexpression rather than genetic loss
    • Endogenous requirement for LTD not established
  7. 2023 High

    Defined the in vivo synaptic function: ICA69 stabilizes PICK1 and is selectively required for NMDAR-dependent LTP and for learning and memory.

    Evidence Ica1 knockout mice with LTP/LTD electrophysiology, PSD fractionation, and behavioral memory testing

    PMID:37251649

    Open questions at the time
    • Molecular basis of LTP-specific (vs LTD) requirement unresolved
    • How PICK1 stabilization is achieved mechanistically not shown
  8. 2002 High

    Established ICA69 as a functionally required autoantigen whose islet-autonomous expression and organ-specific T-cell responses drive autoimmune disease.

    Evidence ICA69-null NOD mice with histopathology, T-cell phenotyping, and islet vs hematopoietic transplantation epistasis

    PMID:11751995 PMID:12383988

    Open questions at the time
    • Link between trafficking function and antigenicity unexplored
    • Mechanism of beta-cell drug toxicity dependence not molecular
  9. 2012 Medium

    Connected an Ica1 promoter SNP to AIRE-mediated transcriptional control, providing a mechanism for variable thymic expression.

    Evidence Luciferase reporter assays and AIRE binding affinity measurement in mTEC and B-cell lines

    PMID:22447927

    Open questions at the time
    • Endogenous AIRE occupancy at the locus not shown
    • Causal in vivo test of the SNP not performed here
  10. 2014 High

    Demonstrated that thymic ICA69 expression is directly required for central tolerance, with its loss causing spontaneous multi-organ autoimmunity.

    Evidence Aire-Cre conditional ICA69 deletion with multi-organ histology and T-cell tolerance assays

    PMID:25088457

    Open questions at the time
    • Why ICA69-reactive T cells damage diverse organs is unexplained
    • Relationship to the BAR/Rab2/PICK1 function not addressed
  11. 2014 Medium

    Extended the ICA69-PICK1-GluA2 axis to spinal nociception, linking the protein to inflammatory pain.

    Evidence ICA69 knockout mice with formalin pain assay, GluA2 phosphorylation/surface Western blots, and microglial immunohistochemistry

    PMID:25547463

    Open questions at the time
    • Causality of microglial activation vs AMPAR changes unresolved
    • Cell-type-specific contributions not separated
  12. 2022 Medium

    Identified a STING-dependent pro-ferroptotic role for ICA69 in septic cardiomyopathy, broadening function beyond trafficking and tolerance.

    Evidence ICA69 knockout in LPS-induced mice with ferroptosis marker quantification and STING expression analysis

    PMID:35397620

    Open questions at the time
    • Direct molecular link between ICA69 and STING not shown
    • Whether BAR/trafficking activity underlies this role is unknown

Open questions

Synthesis pass · forward-looking unresolved questions
  • How ICA69's BAR-domain membrane-deformation and Rab2-effector activities mechanistically connect to its disparate roles in central tolerance and STING-driven ferroptosis remains unresolved.
  • No structural model of the ICA69-PICK1 heteromeric BAR complex
  • No direct biochemical link between ICA69 and STING
  • Unclear whether the trafficking function underlies its antigenicity and tolerance roles

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0008289 lipid binding 2 GO:0098772 molecular function regulator activity 2 GO:0060090 molecular adaptor activity 1
Localization
GO:0005829 cytosol 2 GO:0031410 cytoplasmic vesicle 2 GO:0005794 Golgi apparatus 1
Pathway
R-HSA-112316 Neuronal System 2 R-HSA-168256 Immune System 2 R-HSA-5653656 Vesicle-mediated transport 2
Partners
PICK1PRKCARAB2
Complex memberships
ICA69-PICK1 heteromeric BAR complex

Evidence

Reading pass · 15 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1993 ICA69 (product of ICA1) is a novel 483-amino acid protein expressed in pancreatic beta cells, brain, heart, thyroid, and kidney, with the native molecule migrating at 69 kDa in SDS-PAGE; its mRNA was detected in beta cell lines and islet-cell tumoral tissue, establishing tissue distribution by direct molecular cloning and expression analysis. Lambda gt11 cDNA library screening, Western blotting with specific antibodies, Northern blotting, SDS-PAGE The Journal of clinical investigation Medium 8326004
2000 ICA69 and its C. elegans homologue RIC-19 are conserved regulators of neuroendocrine secretion: a subpopulation of ICA69 is membrane-bound and co-enriched with synaptic vesicles in mouse brain; in beta cells it localizes to synaptic-like microvesicles. Deletion of ric-19 in C. elegans causes aldicarb resistance (defective neurotransmitter secretion), rescued by ric-19 transgene. Subcellular fractionation, immunostaining, C. elegans deletion mutant with aldicarb resistance assay, transgenic rescue Molecular biology of the cell High 11029035
2007 ICA69 is the major binding partner of PICK1 in the brain (>75% of each protein associates with the other); the BAR domain of ICA69 forms heteromeric BAR domain complexes with PICK1 and binds liposomes. ICA69 overexpression redistributes PICK1 from synapses to dendrites, disrupts PICK1-induced AMPA receptor clustering, and reduces synaptic targeting and surface expression of AMPA receptors, indicating that the switch between ICA69-PICK1 heteromers and PICK1 homomers regulates AMPAR trafficking. Co-immunoprecipitation, liposome-binding assay, overexpression in neurons, immunofluorescence colocalization, surface AMPAR quantification The Journal of neuroscience High 18032668
2008 ICA69 is a novel Rab2 effector: it binds to Rab2 in a GTP-dependent manner, and Rab2 recruits ICA69 to membranes. Over-expression of either Rab2 or ICA69 in insulinoma INS-1 cells impairs anterograde transport of secretory granule protein precursors (pro-ICA512, chromogranin A) and reduces stimulated insulin secretion, placing ICA69 in ER-Golgi COPI vesicle transport. Co-immunoprecipitation (GTP-dependent), membrane recruitment assay, overexpression in INS-1 cells, pulse-chase secretory granule trafficking assay, insulin secretion assay European journal of cell biology High 18187231
2002 Genetic disruption of the ICA69 locus in NOD mice prevents lacrimal gland autoimmune disease and greatly reduces salivary gland disease; ICA69-specific T cells accumulate in lymph nodes draining salivary tissue in healthy NOD mice, establishing ICA69 as a functionally required autoantigen in Sjögren's syndrome progression. Genomic knockout (ICA69-null NOD congenic mice), histopathological assessment, T-cell immunophenotyping, peptide immunotherapy Lancet High 12383988
2002 ICA69-null NOD mice develop spontaneous diabetes and insulitis normally but are resistant to cyclophosphamide-accelerated diabetes; transplantation experiments linked this resistance to ICA69 deficiency specifically in islets (not in the hematopoietic compartment), indicating ICA69-dependent beta-cell drug toxicity contributes to CY-accelerated autoimmunity. ICA69 knockout mice, cyclophosphamide treatment, islet and hematopoietic tissue transplantation, diabetes incidence assay Journal of immunology High 11751995
2013 The C-terminal domain of ICA69 (ICAC) interacts with PICK1 and inhibits PKCα-mediated trafficking of the PICK1-PKCα complex to the plasma membrane; overexpression of ICAC (but not the BAR domain alone) blocks this trafficking. Infusion of MBP-ICA69 or MBP-ICAC into cerebellar Purkinje cells inhibits induction of long-term depression at parallel fiber and climbing fiber synapses. Co-immunoprecipitation, overexpression of domain deletion constructs, fluorescence imaging of PICK1-PKCα trafficking, intracellular protein infusion with electrophysiological LTD recording PloS one Medium 24358315
2014 Thymic-specific deletion of ICA69 (Aire-ΔICA69 mice) causes suboptimal central negative selection of ICA69-reactive T cells and spontaneous multi-organ autoimmunity (pancreas, salivary glands, thyroid, stomach), establishing a direct causal link between thymic ICA69 expression and maintenance of peripheral self-tolerance. Tissue-specific conditional knockout (Aire-Cre driven), histological analysis of organ inflammation, T-cell tolerance assays Journal of autoimmunity High 25088457
2014 Loss of ICA69 in mice reduces PICK1 protein levels in spinal cord, increases Ser880 phosphorylation of GluA2 and decreases surface GluA2 expression, leading to enhanced inflammatory pain hypersensitivity after formalin injection; microglial activation in the spinal dorsal horn was also increased. ICA69 knockout mice, formalin pain assay, Western blotting for GluA2 phosphorylation and surface expression, immunohistochemistry for microglial activation Neurochemical research Medium 25547463
2017 In Drosophila, ICA69 colocalizes with α-Spectrin at the neuromuscular junction (NMJ); the N-BAR domain deforms liposomes in vitro; full-length ICA69 and ICAC (but not N-BAR alone) induce filopodia in cultured cells. ICA69 mutants show reduced α-Spectrin at the NMJ and altered synaptic glutamate receptor levels. Reducing PICK1 or Rab2 phenocopies ICA69 mutation, and Rab2 functions genetically upstream of ICA69 regulating ICA69 levels and NMJ organization. RNAi screen, genetic loss-of-function, liposome deformation assay, immunofluorescence colocalization, filopodia induction assay, epistasis analysis Development High 28455372
2012 A single nucleotide polymorphism in the NOD mouse Ica1 promoter increases binding affinity for the transcription factor AIRE, which down-regulates ICA69 expression in medullary thymic epithelial cells; luciferase reporter assays showed NOD Ica1 promoter drives markedly reduced expression compared to C57BL/6 in mTEC and B-cell lines. Luciferase reporter assays, AIRE binding affinity assay, SNP identification, transfection in mTEC and B-cell lines The Journal of biological chemistry Medium 22447927
2002 The ICA1 gene uses alternative core promoters in a tissue-specific manner: the exon A promoter is more active in islet cells and the exon B promoter in neuronal cells; a CREB site within the exon B promoter negatively regulates transcriptional activity in both cell types. 5'-RACE, luciferase reporter constructs, CREB site mutagenesis, transient transfection in islet (RIN) and neuronal (NMB7) cell lines The Journal of biological chemistry Medium 12409289
2022 ICA69 promotes ferroptosis in LPS-treated cardiomyocytes and macrophages by triggering STING production, which drives intracellular lipid peroxidation. ICA69 knockout in LPS-induced mice elevated survival and heart function, reduced ferroptosis markers (PTGS2, MDA, 4HNE, GPX4, SOD, iron, lipid ROS), and reduced inflammatory cytokines, but had no effect on xCT-dependent pathways. ICA69 knockout mice, LPS-induced septic cardiomyopathy model, ferroptosis marker quantification (ELISA, Western blot), STING expression analysis Cell death discovery Medium 35397620
2023 ICA69 regulates PICK1 protein stability and distribution in the hippocampus. Genetic deletion of ICA69 (Ica1 knockout) selectively impairs NMDAR-dependent LTP but not LTD at Schaffer collateral–CA1 synapses without affecting basal AMPAR-mediated currents, dendritic morphology, or PSD AMPAR levels; this correlates with deficits in spatial and associative learning and memory. Ica1 knockout mice, electrophysiological LTP/LTD recording, PSD biochemical fractionation, Western blotting, behavioral tests (spatial and associative memory) Frontiers in molecular neuroscience High 37251649
2024 ICA1/ICA69 overexpression increases APP, ADAM10, and ADAM17 protein levels and increases PKCα protein levels and phosphorylation, shifting APP processing toward non-amyloidogenic pathways via the PICK1-PKCα signaling axis; transcriptome analysis indicated ICA1 regulates G protein-coupled receptor signaling. Overexpression in cell lines, Western blotting for APP/ADAM10/ADAM17/PKCα, transcriptome sequencing, half-life and mRNA level analysis CNS neuroscience & therapeutics Low 38884369

Source papers

Stage 0 corpus · 32 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1993 Islet cell autoantigen 69 kD (ICA69). Molecular cloning and characterization of a novel diabetes-associated autoantigen. The Journal of clinical investigation 224 8326004
2007 PICK1-ICA69 heteromeric BAR domain complex regulates synaptic targeting and surface expression of AMPA receptors. The Journal of neuroscience : the official journal of the Society for Neuroscience 74 18032668
2022 ICA69 aggravates ferroptosis causing septic cardiac dysfunction via STING trafficking. Cell death discovery 57 35397620
1995 Autoantibodies to the islet antigen ICA69 occur in IDDM and in rheumatoid arthritis. Diabetologia 54 7758883
2002 Primary Sjögren's syndrome and deficiency of ICA69. Lancet (London, England) 48 12383988
2008 ICA69 is a novel Rab2 effector regulating ER-Golgi trafficking in insulinoma cells. European journal of cell biology 43 18187231
2000 The diabetes autoantigen ICA69 and its Caenorhabditis elegans homologue, ric-19, are conserved regulators of neuroendocrine secretion. Molecular biology of the cell 38 11029035
1994 Sera from patients with IDDM and healthy individuals have antibodies to ICA69 on western blots but do not immunoprecipitate liquid phase antigen. Journal of autoimmunity 27 7840858
2002 ICA69(null) nonobese diabetic mice develop diabetes, but resist disease acceleration by cyclophosphamide. Journal of immunology (Baltimore, Md. : 1950) 26 11751995
1996 ICA69 is expressed equally in the human endocrine and exocrine pancreas. Diabetologia 25 8777998
1997 Loss of self-tolerance to ICA69 in nonobese diabetic mice. Diabetes 21 9313748
1996 Genomic organization and transcript analysis of ICAp69, a target antigen in diabetic autoimmunity. Genomics 18 8975715
2014 Compromised central tolerance of ICA69 induces multiple organ autoimmunity. Journal of autoimmunity 17 25088457
2002 Alternative core promoters regulate tissue-specific transcription from the autoimmune diabetes-related ICA1 (ICA69) gene locus. The Journal of biological chemistry 16 12409289
1994 ICA1 encoding p69, a protein linked to the development of type 1 diabetes, maps to human chromosome 7p22. Cytogenetics and cell genetics 16 8162706
2013 C-terminal domain of ICA69 interacts with PICK1 and acts on trafficking of PICK1-PKCα complex and cerebellar plasticity. PloS one 14 24358315
1975 Cell division suppression in the Bacillus subtilis div IC-A1 minicell-producing mutant. Journal of bacteriology 13 803958
2017 Regulation of neuromuscular junction organization by Rab2 and its effector ICA69 in Drosophila. Development (Cambridge, England) 12 28455372
2012 Sequence variation in promoter of Ica1 gene, which encodes protein implicated in type 1 diabetes, causes transcription factor autoimmune regulator (AIRE) to increase its binding and down-regulate expression. The Journal of biological chemistry 12 22447927
1997 Molecular cloning of murine ICA69: diabetes-prone mice recognize the human autoimmune-epitope, Tep69, conserved in splice variants from both species. Biochimica et biophysica acta 11 9128175
1998 Anti-BSA antibodies do not cross-react with the 69-kDa islet cell autoantigen ICA69. Journal of autoimmunity 10 9693970
2010 Sex-specific genetic dissection of diabetes in a rodent model identifies Ica1 and Ndufa4 as major candidate genes. Physiological genomics 9 20530722
2019 Analysis of the Epigenome in Multiplex Pre-eclampsia Families Identifies SORD, DGKI, and ICA1 as Novel Candidate Risk Genes. Frontiers in genetics 8 30941163
2014 Loss of ICA69 potentiates long-lasting hyperalgesia after subcutaneous formalin injection into the mouse hindpaw. Neurochemical research 6 25547463
1999 Production of the islet cell antigen ICA69 (p69) with baculovirus expression system: analysis with a solid-phase time-resolved fluorescence method of sera from patients with IDDM and rheumatoid arthritis. Autoimmunity 4 10433084
2024 ICA1 affects APP processing through the PICK1-PKCα signaling pathway. CNS neuroscience & therapeutics 2 38884369
2023 ICA69 regulates activity-dependent synaptic strengthening and learning and memory. Frontiers in molecular neuroscience 2 37251649
1990 Modelling of type 1 diabetes with monoclonal antibody ICA-1. Biomedical science 2 2102778
1983 Clinical studies on ionized calcium using the radiometer ICA1 analyzer. Scandinavian journal of clinical and laboratory investigation. Supplementum 2 6578583
1990 Immunoreactivity of cultured pancreatic islet cells with monoclonal antibody ICA-1. Biomedical science 1 2130918
1989 Pancreatic islet cells in tissue culture: function and immunoreactivity with serum autoantibodies from diabetes type-1 patients and monoclonal antibodies ICA-1. Experimental and clinical endocrinology 1 2673809
1983 An evaluation of the ICA1 ionized calcium analyzer in a clinical chemistry laboratory. Scandinavian journal of clinical and laboratory investigation. Supplementum 0 6578572

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