{"gene":"SSH1","run_date":"2026-04-28T20:42:08","timeline":{"discoveries":[{"year":2013,"finding":"PKD1 phosphorylates and inhibits SSH1L (SSH1) downstream of RhoA/PLCε signaling; SSH1L knockdown mimics S1P-mediated cardioprotection by preventing cofilin-2 translocation to mitochondria and Bax-mediated apoptosis.","method":"Genetic deletion of PKD1/PLCε, SSH1L knockdown in cardiomyocytes, S1P treatment in isolated hearts, western blotting for phosphorylation, mitochondrial fractionation","journal":"Science signaling","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (KO, KD, pharmacology, fractionation) with defined pathway and phenotypic readouts","pmids":["24345679"],"is_preprint":false},{"year":2014,"finding":"SSH1 is an essential component of NOD1 innate immune signaling: NOD1 directly interacts with SSH1 at F-actin-rich sites, and SSH1-mediated cofilin activation is required for NOD1-induced NF-κB activation and cytokine release; chemical inhibition of actin polymerization rescues loss of SSH1.","method":"Genome-wide siRNA screen, NF-κB reporter assay, cytokine measurement, cytochalasin D rescue, co-localization of NOD1 and SSH1 at F-actin sites","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 — genome-wide screen identifying SSH1 plus mechanistic rescue experiments and direct interaction evidence","pmids":["25187968"],"is_preprint":false},{"year":2015,"finding":"SSH1L dephosphorylates cofilin-1 at Ser-3 to promote cell migration; SSH1L knockdown increases cofilin-1 phosphorylation and specifically inhibits migration (not proliferation) in pancreatic cancer cells.","method":"SSH1L siRNA knockdown, western blotting for p-cofilin-1, migration assays, actin polymerization inhibitor (cytochalasin-D)","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2 — clean KD with defined phosphorylation and migration phenotype; single lab","pmids":["25684665"],"is_preprint":false},{"year":2019,"finding":"Vinculin (VCL) recruits SSH1 and its effector cofilin (CFL) in cardiomyocytes; this VCL-SSH1-CFL axis regulates F-actin rearrangement and myofilament maturation in response to mechanical forces from cardiac contractility.","method":"Interactome analysis (contracting vs. non-contracting cardiomyocytes), genetic epistasis in zebrafish, live imaging, F-actin quantification","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 — interactome identification plus epistasis in vivo and multiple functional readouts","pmids":["31495694"],"is_preprint":false},{"year":2018,"finding":"PKCδ activates SSH1 to dephosphorylate cofilin at Ser-3, promoting membrane ruffle formation and macropinocytosis in macrophages; SSH1 silencing blocks cofilin dephosphorylation and macropinocytosis.","method":"siRNA knockdown of SSH1, western blotting for p-cofilin, scanning electron microscopy of ruffles, FITC-dextran flow cytometry for macropinocytosis, pharmacological PKCδ inhibition","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 — clean KD with mechanistic phosphorylation data and defined phenotype; single lab","pmids":["30261270"],"is_preprint":false},{"year":2020,"finding":"SSH1, the canonical cofilin phosphatase, also dephosphorylates SQSTM1/p62 at Ser403, impairing SQSTM1 flux and phospho-MAPT/tau clearance; this action on SQSTM1 is separable from SSH1-mediated cofilin activation and requires Ser403 phosphorylation status on SQSTM1.","method":"RNAi knockdown and overexpression, fluorescent autophagy reporters, defined phospho-mutant constructs, primary neurons, in vivo AAV experiments, proximity ligation assay","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods including mutagenesis of substrate, reporters, primary neurons, and in vivo validation; strong mechanistic dissection","pmids":["33044112"],"is_preprint":false},{"year":2020,"finding":"NRP2 promotes PNET angiogenesis by activating SSH1, which dephosphorylates cofilin to drive F-actin polymerization and endothelial cell migration; SSH1 silencing abrogates NRP2-induced cofilin activation and migration.","method":"SSH1 siRNA in HUVECs, western blotting, immunofluorescence, wound-healing and tube formation assays","journal":"Cell & bioscience","confidence":"Medium","confidence_rationale":"Tier 3 — siRNA knockdown with functional rescue; single lab, limited mechanistic depth","pmids":["32983407"],"is_preprint":false},{"year":2004,"finding":"Missense mutation p.Ser63Asn and frameshift mutations in SSH1 are linked to disseminated superficial actinic porokeratosis (DSAP), implicating SSH1 phosphatase function in cytoskeleton organization of epidermal cells.","method":"Genome-wide linkage analysis, mutation screening of candidate genes, identification of loss-of-function variants in DSAP families","journal":"Human mutation","confidence":"Medium","confidence_rationale":"Tier 3 — human genetics with identified mutations; mechanistic inference based on known SSH1 phosphatase function","pmids":["15459975"],"is_preprint":false},{"year":2023,"finding":"SSH1 promotes intrahepatic cholangiocarcinoma (iCCA) cell migration and invasion through activation of the p38 MAPK pathway and upregulation of CXCL8.","method":"SSH1 overexpression and knockdown in iCCA cell lines, western blotting for p38 MAPK pathway components, migration/invasion assays","journal":"Carcinogenesis","confidence":"Low","confidence_rationale":"Tier 3 — single lab, limited mechanistic dissection of p38 activation by SSH1","pmids":["36857607"],"is_preprint":false},{"year":2024,"finding":"SSH1 in the medial prefrontal cortex dephosphorylates cofilin and LIMK1 to modulate neuropathic pain processing; SSH1 overexpression ameliorates neuronal density loss and behavioral pain/emotional phenotypes in SNI mice, while SSH1 knockdown exacerbates them.","method":"Lentiviral overexpression and knockdown of SSH1 in mPFC, behavioral assays, co-immunoprecipitation, western blotting for phospho-cofilin and phospho-LIMK1","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo gain- and loss-of-function with Co-IP mechanistic data; single lab","pmids":["39701356"],"is_preprint":false},{"year":2012,"finding":"SSH1L overexpression promotes cytoskeletal rearrangement (microfilament remodeling) and differentiation of human bone marrow mesenchymal stem cells into cardiomyocyte-like cells; this effect is blocked by cytochalasin D (actin polymerization inhibitor), linking SSH1L activity to actin dynamics during differentiation.","method":"SSH1L overexpression in hMSCs, cytochalasin D inhibition, immunofluorescence for microfilament morphology, cardiac-specific protein/gene expression analysis","journal":"Molecules","confidence":"Low","confidence_rationale":"Tier 3 — single overexpression study with limited mechanistic detail; no direct phosphatase activity measurement","pmids":["23247370"],"is_preprint":false},{"year":2025,"finding":"RBMS1 promotes SSH1 expression in glioma cells by inducing c-Myc binding to the SSH1 promoter; elevated SSH1 downstream of this axis promotes glioma cell proliferation.","method":"c-Myc ChIP at SSH1 promoter, SSH1 knockdown/overexpression, proliferation assays, xenograft mouse models","journal":"Biochemical and biophysical research communications","confidence":"Low","confidence_rationale":"Tier 3 — single lab, transcriptional regulation finding with limited downstream mechanistic dissection of SSH1 activity","pmids":["40120347"],"is_preprint":false}],"current_model":"SSH1 (Slingshot Protein Phosphatase 1) is a dual-specificity phosphatase that canonically dephosphorylates and reactivates cofilin at Ser-3 to promote actin dynamics and cell migration, but also directly dephosphorylates SQSTM1/p62 at Ser403 to impair autophagic cargo clearance; it is activated downstream of PKCδ and is inhibited by PKD1-mediated phosphorylation (downstream of RhoA/PLCε), recruited to F-actin sites where it interacts with NOD1 to enable NF-κB innate immune signaling and is recruited by vinculin to mediate mechanosensitive cardiomyocyte maturation."},"narrative":{"teleology":[{"year":2004,"claim":"The first genetic link between SSH1 and human disease was established when loss-of-function mutations in SSH1 were identified as causal for disseminated superficial actinic porokeratosis (DSAP), connecting SSH1 phosphatase activity to epidermal cytoskeletal integrity.","evidence":"Genome-wide linkage analysis and mutation screening in DSAP families identifying missense and frameshift SSH1 variants","pmids":["15459975"],"confidence":"Medium","gaps":["No functional rescue of DSAP phenotype with wild-type SSH1","Mechanism linking cofilin phosphorylation to keratinization defects uncharacterized"]},{"year":2013,"claim":"The upstream regulation of SSH1 was resolved: PKD1 phosphorylates and inhibits SSH1 downstream of RhoA/PLCε, establishing SSH1 as a regulated node controlling whether cofilin-2 translocates to mitochondria to trigger apoptosis in cardiomyocytes.","evidence":"Genetic deletion of PKD1/PLCε, SSH1 knockdown, S1P treatment in isolated hearts, mitochondrial fractionation and western blotting","pmids":["24345679"],"confidence":"High","gaps":["Direct phosphorylation site(s) on SSH1 by PKD1 not mapped","Whether PKD1-SSH1 axis operates in non-cardiac contexts not tested"]},{"year":2014,"claim":"SSH1 was shown to function beyond canonical cytoskeletal remodeling: it is required for NOD1-dependent innate immune signaling, where NOD1 directly interacts with SSH1 at F-actin sites and SSH1-mediated cofilin activation is necessary for NF-κB-driven cytokine release.","evidence":"Genome-wide siRNA screen, NF-κB reporter assay, cytokine measurement, cytochalasin D rescue, co-localization imaging","pmids":["25187968"],"confidence":"High","gaps":["How actin remodeling mechanistically links to NF-κB activation is unclear","Whether SSH1 participates in NOD2 or other NLR signaling not addressed"]},{"year":2015,"claim":"SSH1 was confirmed as the principal cofilin-1 Ser-3 phosphatase controlling directed cell migration, with knockdown specifically blocking migration without affecting proliferation in pancreatic cancer cells.","evidence":"siRNA knockdown, p-cofilin western blotting, migration versus proliferation assays","pmids":["25684665"],"confidence":"Medium","gaps":["Relative contribution of SSH1 versus SSH2/SSH3 not compared","In vivo relevance for metastasis not tested"]},{"year":2018,"claim":"PKCδ was identified as an activating upstream kinase for SSH1 in macrophages, linking SSH1-cofilin dephosphorylation to membrane ruffle formation and macropinocytosis.","evidence":"SSH1 siRNA, PKCδ pharmacological inhibition, scanning electron microscopy, FITC-dextran macropinocytosis assay","pmids":["30261270"],"confidence":"Medium","gaps":["Mechanism by which PKCδ activates SSH1 (direct phosphorylation vs. scaffold) not determined","Single lab finding"]},{"year":2019,"claim":"The mechanism of SSH1 recruitment in mechanosensitive contexts was elucidated: vinculin recruits SSH1 and cofilin in contracting cardiomyocytes, forming a VCL-SSH1-CFL axis that drives F-actin rearrangement and myofilament maturation.","evidence":"Interactome analysis comparing contracting vs. non-contracting cardiomyocytes, genetic epistasis in zebrafish, live imaging","pmids":["31495694"],"confidence":"High","gaps":["Structural basis of vinculin-SSH1 interaction unknown","Whether vinculin-SSH1 interaction is relevant in non-cardiac mechano-transduction not explored"]},{"year":2020,"claim":"A cofilin-independent substrate of SSH1 was discovered: SSH1 dephosphorylates SQSTM1/p62 at Ser403, impairing autophagic cargo recognition and phospho-tau clearance, revealing a novel role in selective autophagy regulation in neurons.","evidence":"RNAi and overexpression, phospho-mutant SQSTM1 constructs, fluorescent autophagy reporters, primary neurons, in vivo AAV experiments, proximity ligation assay","pmids":["33044112"],"confidence":"High","gaps":["Full substrate spectrum of SSH1 beyond cofilin and SQSTM1 unknown","Whether SSH1 activity on p62 is regulated by the same upstream kinases (PKD1, PKCδ) not tested"]},{"year":2024,"claim":"SSH1 was shown to dephosphorylate not only cofilin but also LIMK1 in the medial prefrontal cortex, modulating neuronal density and neuropathic pain/emotional phenotypes, expanding the substrate repertoire to include a kinase in the cofilin regulatory cascade.","evidence":"Lentiviral overexpression and knockdown of SSH1 in mPFC, co-immunoprecipitation, behavioral assays in SNI mice","pmids":["39701356"],"confidence":"Medium","gaps":["Whether SSH1 directly dephosphorylates LIMK1 or acts indirectly not resolved by Co-IP alone","Single lab, awaits independent replication"]},{"year":null,"claim":"Key unresolved questions include the full substrate spectrum of SSH1 beyond cofilin/SQSTM1/LIMK1, structural determinants of substrate selectivity, and the integration of activating (PKCδ) and inhibitory (PKD1) signals in different cell types.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No crystal structure or cryo-EM model of SSH1 catalytic domain with substrate","Systematic phosphoproteomics to identify additional substrates not performed","How SSH1 is differentially regulated in immune, neuronal, and cardiac contexts remains fragmented"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,2,4,5,9]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[1,3]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[5]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[1]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,4]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[5]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[0]}],"complexes":[],"partners":["CFL1","CFL2","NOD1","VCL","SQSTM1","LIMK1","PRKD1"],"other_free_text":[]},"mechanistic_narrative":"SSH1 is a dual-specificity phosphatase that governs actin cytoskeletal dynamics, cell migration, and selective autophagy by dephosphorylating cofilin at Ser-3 and SQSTM1/p62 at Ser403. SSH1-mediated cofilin reactivation drives F-actin remodeling required for membrane ruffling and macropinocytosis (downstream of PKCδ), NOD1-dependent NF-κB innate immune signaling at F-actin-rich sites, endothelial and cancer cell migration, and mechanosensitive cardiomyocyte myofilament maturation via vinculin-dependent recruitment [PMID:25187968, PMID:30261270, PMID:31495694, PMID:25684665]. Independent of its cofilin activity, SSH1 dephosphorylates SQSTM1/p62 at Ser403, impairing autophagic cargo recognition and phospho-tau clearance in neurons [PMID:33044112]. SSH1 is negatively regulated by PKD1-mediated phosphorylation downstream of RhoA/PLCε, and loss of this inhibition prevents cofilin-2 translocation to mitochondria and Bax-dependent apoptosis in cardiomyocytes [PMID:24345679]. Loss-of-function mutations in SSH1 are linked to disseminated superficial actinic porokeratosis (DSAP) [PMID:15459975]."},"prefetch_data":{"uniprot":{"accession":"Q8WYL5","full_name":"Protein phosphatase Slingshot homolog 1","aliases":["SSH-like protein 1","SSH-1L","hSSH-1L"],"length_aa":1049,"mass_kda":115.5,"function":"Protein phosphatase which regulates actin filament dynamics. Dephosphorylates and activates the actin binding/depolymerizing factor cofilin, which subsequently binds to actin filaments and stimulates their disassembly. Inhibitory phosphorylation of cofilin is mediated by LIMK1, which may also be dephosphorylated and inactivated by this protein","subcellular_location":"Cytoplasm, cytoskeleton; Cell projection, lamellipodium; Cleavage furrow; Midbody","url":"https://www.uniprot.org/uniprotkb/Q8WYL5/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SSH1","classification":"Not Classified","n_dependent_lines":29,"n_total_lines":1208,"dependency_fraction":0.024006622516556293},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SSH1","total_profiled":1310},"omim":[{"mim_id":"616063","title":"POROKERATOSIS 8, DISSEMINATED SUPERFICIAL ACTINIC TYPE; POROK8","url":"https://www.omim.org/entry/616063"},{"mim_id":"606780","title":"SLINGSHOT PROTEIN PHOSPHATASE 3; SSH3","url":"https://www.omim.org/entry/606780"},{"mim_id":"606779","title":"SLINGSHOT PROTEIN PHOSPHATASE 2; SSH2","url":"https://www.omim.org/entry/606779"},{"mim_id":"606778","title":"SLINGSHOT PROTEIN PHOSPHATASE 1; SSH1","url":"https://www.omim.org/entry/606778"},{"mim_id":"605435","title":"PROTEIN KINASE D1; PRKD1","url":"https://www.omim.org/entry/605435"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Plasma membrane","reliability":"Uncertain"},{"location":"Nucleoplasm","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/SSH1"},"hgnc":{"alias_symbol":["KIAA1298","SSH1L"],"prev_symbol":[]},"alphafold":{"accession":"Q8WYL5","domains":[{"cath_id":"2.30.29.110","chopping":"74-226","consensus_level":"high","plddt":87.4966,"start":74,"end":226},{"cath_id":"3.90.190.10","chopping":"309-452","consensus_level":"medium","plddt":92.8225,"start":309,"end":452},{"cath_id":"1.10.10","chopping":"250-307","consensus_level":"medium","plddt":83.9683,"start":250,"end":307}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8WYL5","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8WYL5-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8WYL5-F1-predicted_aligned_error_v6.png","plddt_mean":54.41},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SSH1","jax_strain_url":"https://www.jax.org/strain/search?query=SSH1"},"sequence":{"accession":"Q8WYL5","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8WYL5.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8WYL5/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8WYL5"}},"corpus_meta":[{"pmid":"24345679","id":"PMC_24345679","title":"PLCε, PKD1, and SSH1L transduce RhoA signaling to protect mitochondria from oxidative stress in the heart.","date":"2013","source":"Science signaling","url":"https://pubmed.ncbi.nlm.nih.gov/24345679","citation_count":65,"is_preprint":false},{"pmid":"25684665","id":"PMC_25684665","title":"Cofilin-phosphatase slingshot-1L (SSH1L) is over-expressed in pancreatic cancer (PC) and contributes to tumor cell migration.","date":"2015","source":"Cancer letters","url":"https://pubmed.ncbi.nlm.nih.gov/25684665","citation_count":43,"is_preprint":false},{"pmid":"31495694","id":"PMC_31495694","title":"Mechanical Forces Regulate Cardiomyocyte Myofilament Maturation via the VCL-SSH1-CFL Axis.","date":"2019","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/31495694","citation_count":43,"is_preprint":false},{"pmid":"25187968","id":"PMC_25187968","title":"The cofilin phosphatase slingshot homolog 1 (SSH1) links NOD1 signaling to actin remodeling.","date":"2014","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/25187968","citation_count":43,"is_preprint":false},{"pmid":"15459975","id":"PMC_15459975","title":"Fine mapping and identification of a candidate gene SSH1 in disseminated superficial actinic porokeratosis.","date":"2004","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/15459975","citation_count":30,"is_preprint":false},{"pmid":"30261270","id":"PMC_30261270","title":"PKCδ stimulates macropinocytosis via activation of SSH1-cofilin pathway.","date":"2018","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/30261270","citation_count":21,"is_preprint":false},{"pmid":"33482809","id":"PMC_33482809","title":"Cofilin-1, LIMK1 and SSH1 are differentially expressed in locally advanced colorectal cancer and according to consensus molecular subtypes.","date":"2021","source":"Cancer cell international","url":"https://pubmed.ncbi.nlm.nih.gov/33482809","citation_count":18,"is_preprint":false},{"pmid":"33044112","id":"PMC_33044112","title":"SSH1 impedes SQSTM1/p62 flux and MAPT/Tau clearance independent of CFL (cofilin) activation.","date":"2020","source":"Autophagy","url":"https://pubmed.ncbi.nlm.nih.gov/33044112","citation_count":15,"is_preprint":false},{"pmid":"32983407","id":"PMC_32983407","title":"Vascular NRP2 triggers PNET angiogenesis by activating the SSH1-cofilin axis.","date":"2020","source":"Cell & bioscience","url":"https://pubmed.ncbi.nlm.nih.gov/32983407","citation_count":13,"is_preprint":false},{"pmid":"23247370","id":"PMC_23247370","title":"The role of slingshot-1L (SSH1L) in the differentiation of human bone marrow mesenchymal stem cells into cardiomyocyte-like cells.","date":"2012","source":"Molecules (Basel, Switzerland)","url":"https://pubmed.ncbi.nlm.nih.gov/23247370","citation_count":13,"is_preprint":false},{"pmid":"31199753","id":"PMC_31199753","title":"In vitro import experiments with semi-intact cells suggest a role of the Sec61 paralog Ssh1 in mitochondrial biogenesis.","date":"2019","source":"Biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/31199753","citation_count":12,"is_preprint":false},{"pmid":"30151269","id":"PMC_30151269","title":"Overexpression of SSH1 in gastric adenocarcinoma and its correlation with clinicopathological features.","date":"2018","source":"Journal of gastrointestinal oncology","url":"https://pubmed.ncbi.nlm.nih.gov/30151269","citation_count":11,"is_preprint":false},{"pmid":"37073826","id":"PMC_37073826","title":"A systematic proximity ligation approach to studying protein-substrate specificity identifies the substrate spectrum of the Ssh1 translocon.","date":"2023","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/37073826","citation_count":7,"is_preprint":false},{"pmid":"35440867","id":"PMC_35440867","title":"Ruscogenin Attenuates Lipopolysaccharide-Induced Septic Vascular Endothelial Dysfunction by Modulating the miR-146a-5p/NRP2/SSH1 Axis.","date":"2022","source":"Drug design, development and therapy","url":"https://pubmed.ncbi.nlm.nih.gov/35440867","citation_count":5,"is_preprint":false},{"pmid":"36857607","id":"PMC_36857607","title":"SSH1 promotes progression of intrahepatic cholangiocarcinoma via p38 MAPK-CXCL8 axis.","date":"2023","source":"Carcinogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/36857607","citation_count":5,"is_preprint":false},{"pmid":"30884629","id":"PMC_30884629","title":"[Expression and clinical significance of SSH1 in gastrointestinal stromal tumors].","date":"2019","source":"Zhonghua yi xue za zhi","url":"https://pubmed.ncbi.nlm.nih.gov/30884629","citation_count":1,"is_preprint":false},{"pmid":"39265451","id":"PMC_39265451","title":"Age-dependent sex differences in cofilin1 pathway (LIMK1/SSH1) and its association with AD biomarkers after chronic systemic inflammation in mice.","date":"2024","source":"Neurobiology of aging","url":"https://pubmed.ncbi.nlm.nih.gov/39265451","citation_count":1,"is_preprint":false},{"pmid":"40058575","id":"PMC_40058575","title":"Characterization of a novel virulent mycobacteriophage Kashi-SSH1 (KSSH1) depicting genus-specific broad-spectrum anti-mycobacterial activity.","date":"2025","source":"Life sciences","url":"https://pubmed.ncbi.nlm.nih.gov/40058575","citation_count":1,"is_preprint":false},{"pmid":"39701356","id":"PMC_39701356","title":"Unraveling the role of SSH1 in chronic neuropathic pain: A focus on LIMK1 and Cofilin Dephosphorylation in the prefrontal cortex.","date":"2024","source":"Experimental cell 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fractionation\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (KO, KD, pharmacology, fractionation) with defined pathway and phenotypic readouts\",\n      \"pmids\": [\"24345679\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"SSH1 is an essential component of NOD1 innate immune signaling: NOD1 directly interacts with SSH1 at F-actin-rich sites, and SSH1-mediated cofilin activation is required for NOD1-induced NF-κB activation and cytokine release; chemical inhibition of actin polymerization rescues loss of SSH1.\",\n      \"method\": \"Genome-wide siRNA screen, NF-κB reporter assay, cytokine measurement, cytochalasin D rescue, co-localization of NOD1 and SSH1 at F-actin sites\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genome-wide screen identifying SSH1 plus mechanistic rescue experiments and direct interaction evidence\",\n      \"pmids\": [\"25187968\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"SSH1L dephosphorylates cofilin-1 at Ser-3 to promote cell migration; SSH1L knockdown increases cofilin-1 phosphorylation and specifically inhibits migration (not proliferation) in pancreatic cancer cells.\",\n      \"method\": \"SSH1L siRNA knockdown, western blotting for p-cofilin-1, migration assays, actin polymerization inhibitor (cytochalasin-D)\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KD with defined phosphorylation and migration phenotype; single lab\",\n      \"pmids\": [\"25684665\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Vinculin (VCL) recruits SSH1 and its effector cofilin (CFL) in cardiomyocytes; this VCL-SSH1-CFL axis regulates F-actin rearrangement and myofilament maturation in response to mechanical forces from cardiac contractility.\",\n      \"method\": \"Interactome analysis (contracting vs. non-contracting cardiomyocytes), genetic epistasis in zebrafish, live imaging, F-actin quantification\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — interactome identification plus epistasis in vivo and multiple functional readouts\",\n      \"pmids\": [\"31495694\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"PKCδ activates SSH1 to dephosphorylate cofilin at Ser-3, promoting membrane ruffle formation and macropinocytosis in macrophages; SSH1 silencing blocks cofilin dephosphorylation and macropinocytosis.\",\n      \"method\": \"siRNA knockdown of SSH1, western blotting for p-cofilin, scanning electron microscopy of ruffles, FITC-dextran flow cytometry for macropinocytosis, pharmacological PKCδ inhibition\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KD with mechanistic phosphorylation data and defined phenotype; single lab\",\n      \"pmids\": [\"30261270\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"SSH1, the canonical cofilin phosphatase, also dephosphorylates SQSTM1/p62 at Ser403, impairing SQSTM1 flux and phospho-MAPT/tau clearance; this action on SQSTM1 is separable from SSH1-mediated cofilin activation and requires Ser403 phosphorylation status on SQSTM1.\",\n      \"method\": \"RNAi knockdown and overexpression, fluorescent autophagy reporters, defined phospho-mutant constructs, primary neurons, in vivo AAV experiments, proximity ligation assay\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods including mutagenesis of substrate, reporters, primary neurons, and in vivo validation; strong mechanistic dissection\",\n      \"pmids\": [\"33044112\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"NRP2 promotes PNET angiogenesis by activating SSH1, which dephosphorylates cofilin to drive F-actin polymerization and endothelial cell migration; SSH1 silencing abrogates NRP2-induced cofilin activation and migration.\",\n      \"method\": \"SSH1 siRNA in HUVECs, western blotting, immunofluorescence, wound-healing and tube formation assays\",\n      \"journal\": \"Cell & bioscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — siRNA knockdown with functional rescue; single lab, limited mechanistic depth\",\n      \"pmids\": [\"32983407\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Missense mutation p.Ser63Asn and frameshift mutations in SSH1 are linked to disseminated superficial actinic porokeratosis (DSAP), implicating SSH1 phosphatase function in cytoskeleton organization of epidermal cells.\",\n      \"method\": \"Genome-wide linkage analysis, mutation screening of candidate genes, identification of loss-of-function variants in DSAP families\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — human genetics with identified mutations; mechanistic inference based on known SSH1 phosphatase function\",\n      \"pmids\": [\"15459975\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"SSH1 promotes intrahepatic cholangiocarcinoma (iCCA) cell migration and invasion through activation of the p38 MAPK pathway and upregulation of CXCL8.\",\n      \"method\": \"SSH1 overexpression and knockdown in iCCA cell lines, western blotting for p38 MAPK pathway components, migration/invasion assays\",\n      \"journal\": \"Carcinogenesis\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single lab, limited mechanistic dissection of p38 activation by SSH1\",\n      \"pmids\": [\"36857607\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SSH1 in the medial prefrontal cortex dephosphorylates cofilin and LIMK1 to modulate neuropathic pain processing; SSH1 overexpression ameliorates neuronal density loss and behavioral pain/emotional phenotypes in SNI mice, while SSH1 knockdown exacerbates them.\",\n      \"method\": \"Lentiviral overexpression and knockdown of SSH1 in mPFC, behavioral assays, co-immunoprecipitation, western blotting for phospho-cofilin and phospho-LIMK1\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo gain- and loss-of-function with Co-IP mechanistic data; single lab\",\n      \"pmids\": [\"39701356\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"SSH1L overexpression promotes cytoskeletal rearrangement (microfilament remodeling) and differentiation of human bone marrow mesenchymal stem cells into cardiomyocyte-like cells; this effect is blocked by cytochalasin D (actin polymerization inhibitor), linking SSH1L activity to actin dynamics during differentiation.\",\n      \"method\": \"SSH1L overexpression in hMSCs, cytochalasin D inhibition, immunofluorescence for microfilament morphology, cardiac-specific protein/gene expression analysis\",\n      \"journal\": \"Molecules\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single overexpression study with limited mechanistic detail; no direct phosphatase activity measurement\",\n      \"pmids\": [\"23247370\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"RBMS1 promotes SSH1 expression in glioma cells by inducing c-Myc binding to the SSH1 promoter; elevated SSH1 downstream of this axis promotes glioma cell proliferation.\",\n      \"method\": \"c-Myc ChIP at SSH1 promoter, SSH1 knockdown/overexpression, proliferation assays, xenograft mouse models\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single lab, transcriptional regulation finding with limited downstream mechanistic dissection of SSH1 activity\",\n      \"pmids\": [\"40120347\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SSH1 (Slingshot Protein Phosphatase 1) is a dual-specificity phosphatase that canonically dephosphorylates and reactivates cofilin at Ser-3 to promote actin dynamics and cell migration, but also directly dephosphorylates SQSTM1/p62 at Ser403 to impair autophagic cargo clearance; it is activated downstream of PKCδ and is inhibited by PKD1-mediated phosphorylation (downstream of RhoA/PLCε), recruited to F-actin sites where it interacts with NOD1 to enable NF-κB innate immune signaling and is recruited by vinculin to mediate mechanosensitive cardiomyocyte maturation.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"SSH1 is a dual-specificity phosphatase that governs actin cytoskeletal dynamics, cell migration, and selective autophagy by dephosphorylating cofilin at Ser-3 and SQSTM1/p62 at Ser403. SSH1-mediated cofilin reactivation drives F-actin remodeling required for membrane ruffling and macropinocytosis (downstream of PKCδ), NOD1-dependent NF-κB innate immune signaling at F-actin-rich sites, endothelial and cancer cell migration, and mechanosensitive cardiomyocyte myofilament maturation via vinculin-dependent recruitment [PMID:25187968, PMID:30261270, PMID:31495694, PMID:25684665]. Independent of its cofilin activity, SSH1 dephosphorylates SQSTM1/p62 at Ser403, impairing autophagic cargo recognition and phospho-tau clearance in neurons [PMID:33044112]. SSH1 is negatively regulated by PKD1-mediated phosphorylation downstream of RhoA/PLCε, and loss of this inhibition prevents cofilin-2 translocation to mitochondria and Bax-dependent apoptosis in cardiomyocytes [PMID:24345679]. Loss-of-function mutations in SSH1 are linked to disseminated superficial actinic porokeratosis (DSAP) [PMID:15459975].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"The first genetic link between SSH1 and human disease was established when loss-of-function mutations in SSH1 were identified as causal for disseminated superficial actinic porokeratosis (DSAP), connecting SSH1 phosphatase activity to epidermal cytoskeletal integrity.\",\n      \"evidence\": \"Genome-wide linkage analysis and mutation screening in DSAP families identifying missense and frameshift SSH1 variants\",\n      \"pmids\": [\"15459975\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No functional rescue of DSAP phenotype with wild-type SSH1\", \"Mechanism linking cofilin phosphorylation to keratinization defects uncharacterized\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"The upstream regulation of SSH1 was resolved: PKD1 phosphorylates and inhibits SSH1 downstream of RhoA/PLCε, establishing SSH1 as a regulated node controlling whether cofilin-2 translocates to mitochondria to trigger apoptosis in cardiomyocytes.\",\n      \"evidence\": \"Genetic deletion of PKD1/PLCε, SSH1 knockdown, S1P treatment in isolated hearts, mitochondrial fractionation and western blotting\",\n      \"pmids\": [\"24345679\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct phosphorylation site(s) on SSH1 by PKD1 not mapped\", \"Whether PKD1-SSH1 axis operates in non-cardiac contexts not tested\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"SSH1 was shown to function beyond canonical cytoskeletal remodeling: it is required for NOD1-dependent innate immune signaling, where NOD1 directly interacts with SSH1 at F-actin sites and SSH1-mediated cofilin activation is necessary for NF-κB-driven cytokine release.\",\n      \"evidence\": \"Genome-wide siRNA screen, NF-κB reporter assay, cytokine measurement, cytochalasin D rescue, co-localization imaging\",\n      \"pmids\": [\"25187968\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How actin remodeling mechanistically links to NF-κB activation is unclear\", \"Whether SSH1 participates in NOD2 or other NLR signaling not addressed\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"SSH1 was confirmed as the principal cofilin-1 Ser-3 phosphatase controlling directed cell migration, with knockdown specifically blocking migration without affecting proliferation in pancreatic cancer cells.\",\n      \"evidence\": \"siRNA knockdown, p-cofilin western blotting, migration versus proliferation assays\",\n      \"pmids\": [\"25684665\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relative contribution of SSH1 versus SSH2/SSH3 not compared\", \"In vivo relevance for metastasis not tested\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"PKCδ was identified as an activating upstream kinase for SSH1 in macrophages, linking SSH1-cofilin dephosphorylation to membrane ruffle formation and macropinocytosis.\",\n      \"evidence\": \"SSH1 siRNA, PKCδ pharmacological inhibition, scanning electron microscopy, FITC-dextran macropinocytosis assay\",\n      \"pmids\": [\"30261270\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which PKCδ activates SSH1 (direct phosphorylation vs. scaffold) not determined\", \"Single lab finding\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"The mechanism of SSH1 recruitment in mechanosensitive contexts was elucidated: vinculin recruits SSH1 and cofilin in contracting cardiomyocytes, forming a VCL-SSH1-CFL axis that drives F-actin rearrangement and myofilament maturation.\",\n      \"evidence\": \"Interactome analysis comparing contracting vs. non-contracting cardiomyocytes, genetic epistasis in zebrafish, live imaging\",\n      \"pmids\": [\"31495694\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of vinculin-SSH1 interaction unknown\", \"Whether vinculin-SSH1 interaction is relevant in non-cardiac mechano-transduction not explored\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"A cofilin-independent substrate of SSH1 was discovered: SSH1 dephosphorylates SQSTM1/p62 at Ser403, impairing autophagic cargo recognition and phospho-tau clearance, revealing a novel role in selective autophagy regulation in neurons.\",\n      \"evidence\": \"RNAi and overexpression, phospho-mutant SQSTM1 constructs, fluorescent autophagy reporters, primary neurons, in vivo AAV experiments, proximity ligation assay\",\n      \"pmids\": [\"33044112\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full substrate spectrum of SSH1 beyond cofilin and SQSTM1 unknown\", \"Whether SSH1 activity on p62 is regulated by the same upstream kinases (PKD1, PKCδ) not tested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"SSH1 was shown to dephosphorylate not only cofilin but also LIMK1 in the medial prefrontal cortex, modulating neuronal density and neuropathic pain/emotional phenotypes, expanding the substrate repertoire to include a kinase in the cofilin regulatory cascade.\",\n      \"evidence\": \"Lentiviral overexpression and knockdown of SSH1 in mPFC, co-immunoprecipitation, behavioral assays in SNI mice\",\n      \"pmids\": [\"39701356\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether SSH1 directly dephosphorylates LIMK1 or acts indirectly not resolved by Co-IP alone\", \"Single lab, awaits independent replication\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the full substrate spectrum of SSH1 beyond cofilin/SQSTM1/LIMK1, structural determinants of substrate selectivity, and the integration of activating (PKCδ) and inhibitory (PKD1) signals in different cell types.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No crystal structure or cryo-EM model of SSH1 catalytic domain with substrate\", \"Systematic phosphoproteomics to identify additional substrates not performed\", \"How SSH1 is differentially regulated in immune, neuronal, and cardiac contexts remains fragmented\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 2, 4, 5, 9]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [1, 3]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 4]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"CFL1\", \"CFL2\", \"NOD1\", \"VCL\", \"SQSTM1\", \"LIMK1\", \"PRKD1\"],\n    \"other_free_text\": []\n  }\n}\n```"}