{"gene":"BORCS8","run_date":"2026-06-09T22:02:45","timeline":{"discoveries":[{"year":2024,"finding":"BORCS8 is a subunit of the BLOC-one-related complex (BORC) that associates with the cytosolic face of lysosomes and promotes anterograde transport of lysosomes toward the cell periphery in non-neuronal cells and toward the distal axon in neurons by sequentially recruiting the small GTPase ARL8 and kinesin-1 and -3 microtubule motors. Disease-associated missense variants (p.Ser29Pro, p.Ser42Pro, p.Thr66Pro) are expressed at normal levels but show reduced assembly with other BORC subunits and reduced ability to drive peripheral lysosome distribution; a frameshift variant (p.Asn26Trpfs*51) is expressed at lower levels and is completely incapable of assembling with BORC subunits or promoting lysosome distribution.","method":"Heterologous transfection rescue assays in cultured cells (lysosome distribution quantification, co-assembly assays); zebrafish borcs8 knockout for in vivo validation","journal":"Brain : a journal of neurology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (transfection rescue, co-assembly, lysosome distribution imaging, zebrafish KO), variant-level mechanistic dissection, peer-reviewed","pmids":["38128568"],"is_preprint":false},{"year":2026,"finding":"BORCS8 mediates acidification of early endosomes during viral entry, a process that facilitates degradation of virus particles; loss-of-function of BORCS8 identified in a systematic arrayed screen modulates SARS-CoV-2 infection.","method":"Arrayed loss-of-function screen (siRNA/shRNA) against 285 ISGs across eight viruses; mechanistic follow-up demonstrating early endosome acidification","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — pan-ISG screen with mechanistic follow-up on endosome acidification for BORCS8 specifically, but single study and limited orthogonal validation described in abstract","pmids":["42103727"],"is_preprint":false},{"year":2026,"finding":"BORCS8 variants in the context of BORC dysfunction impair anterograde lysosome transport and autophagy, establishing that BORCS8/BORC function is required for lysosomal dynamics and autophagy in non-neuronal cells and iPSC-derived neurons (contextual finding from BLOC1S1 study confirming BORCS8-BORC pathway).","method":"BLOC1S1-KO functional studies with parallel reference to BORCS8 disease variants; lysosome transport assays, autophagy assays in iPSC-derived neurons","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO plus iPSC-derived neuron assays, but BORCS8 is referenced indirectly as a comparator; peer-reviewed","pmids":["41887224"],"is_preprint":false}],"current_model":"BORCS8 is a subunit of the BORC multiprotein complex that localizes to the cytosolic face of lysosomes, where it promotes anterograde lysosomal transport toward the cell periphery (and distal axon in neurons) by recruiting ARL8 and kinesin motors; it also mediates early endosome acidification to facilitate degradation of endocytosed cargo including viral particles, and loss-of-function variants that disrupt BORC assembly and lysosome dynamics cause an infantile-onset neurodegenerative disorder."},"narrative":{"mechanistic_narrative":"BORCS8 is a subunit of the BLOC-one-related complex (BORC) that associates with the cytosolic face of lysosomes and drives their anterograde transport toward the cell periphery in non-neuronal cells and toward the distal axon in neurons, acting by sequentially recruiting the small GTPase ARL8 and kinesin-1 and -3 microtubule motors [PMID:38128568]. Within this pathway BORCS8/BORC function is required for lysosomal dynamics and autophagy in both non-neuronal cells and iPSC-derived neurons [PMID:41887224]. BORCS8 additionally mediates acidification of early endosomes during viral entry, facilitating degradation of virus particles and thereby modulating SARS-CoV-2 infection [PMID:42103727]. Disease-associated missense variants (p.Ser29Pro, p.Ser42Pro, p.Thr66Pro) are expressed normally but assemble poorly with other BORC subunits and fail to drive peripheral lysosome distribution, while a frameshift variant (p.Asn26Trpfs*51) is expressed at reduced levels and cannot assemble with BORC or promote lysosome distribution, causing an infantile-onset neurodegenerative disorder [PMID:38128568].","teleology":[{"year":2024,"claim":"Established that BORCS8 is a functional BORC subunit whose disease variants impair complex assembly and lysosome positioning, linking molecular defects to an inherited neurodegenerative disorder.","evidence":"Heterologous transfection rescue and co-assembly assays in cultured cells with lysosome distribution imaging; zebrafish borcs8 knockout for in vivo validation","pmids":["38128568"],"confidence":"High","gaps":["Structural basis for how the Ser/Thr-to-Pro substitutions disrupt BORC assembly is not resolved","Direct biochemical demonstration of ARL8/kinesin recruitment by BORCS8 specifically is not isolated from the complex","Mechanism connecting impaired lysosome distribution to neuronal degeneration is not defined"]},{"year":2026,"claim":"Extended BORCS8 function beyond lysosome positioning to early endosome acidification during viral entry, implicating it in antiviral degradation of internalized particles.","evidence":"Arrayed siRNA/shRNA loss-of-function screen across eight viruses with mechanistic follow-up on early endosome acidification","pmids":["42103727"],"confidence":"Medium","gaps":["Single study with limited orthogonal validation of the acidification mechanism","How a BORC/lysosome-positioning subunit controls early endosome pH is not mechanistically explained","Whether the antiviral role depends on the same BORC assembly required for lysosome transport is unknown"]},{"year":2026,"claim":"Confirmed within a BLOC1S1-focused study that the BORCS8/BORC pathway is required for anterograde lysosome transport and autophagy in iPSC-derived neurons, reinforcing its neuronal relevance.","evidence":"BLOC1S1-KO functional studies with lysosome transport and autophagy assays in iPSC-derived neurons, referencing BORCS8 disease variants as comparators","pmids":["41887224"],"confidence":"Medium","gaps":["BORCS8 is referenced indirectly as a comparator rather than directly perturbed in this study","The contribution of BORCS8 versus other BORC subunits to the autophagy defect is not separated"]},{"year":null,"claim":"How the same BORCS8/BORC machinery coordinates lysosome positioning, autophagy, and early endosome acidification, and how its disruption produces neurodegeneration, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of BORCS8 within the assembled BORC complex","Mechanistic link between lysosome mispositioning and neuronal cell death undefined","Reconciliation of the endosomal acidification role with the established lysosome-transport role"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[0]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[1]}],"pathway":[{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[2]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[0]}],"complexes":["BORC"],"partners":["ARL8","BLOC1S1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q96FH0","full_name":"BLOC-1-related complex subunit 8","aliases":["MEF2B neighbor"],"length_aa":119,"mass_kda":13.4,"function":"As part of the BLOC-one-related complex (BORC), it plays a role in the movement and localization of lysosomes at the cell periphery (PubMed:25898167, PubMed:38128568). Associated with the cytosolic face of lysosomes, BORC recruits ARL8B to the lysosomal membrane and couples lysosomes to microtubule plus-end-directed kinesin motors, driving lysosome movement toward the cell periphery","subcellular_location":"Lysosome membrane","url":"https://www.uniprot.org/uniprotkb/Q96FH0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/BORCS8","classification":"Not Classified","n_dependent_lines":99,"n_total_lines":1208,"dependency_fraction":0.08195364238410596},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/BORCS8","total_profiled":1310},"omim":[{"mim_id":"620987","title":"NEURODEGENERATION, INFANTILE-ONSET, WITH OPTIC ATROPHY AND BRAIN ABNORMALITIES; NDOABA","url":"https://www.omim.org/entry/620987"},{"mim_id":"616601","title":"BLOC1-RELATED COMPLEX, SUBUNIT 8; BORCS8","url":"https://www.omim.org/entry/616601"},{"mim_id":"616600","title":"BLOC1-RELATED COMPLEX, SUBUNIT 7; BORCS7","url":"https://www.omim.org/entry/616600"},{"mim_id":"616599","title":"BLOC1-RELATED COMPLEX, SUBUNIT 6; BORCS6","url":"https://www.omim.org/entry/616599"},{"mim_id":"616598","title":"BLOC1-RELATED COMPLEX, SUBUNIT 5; BORCS5","url":"https://www.omim.org/entry/616598"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Vesicles","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/BORCS8"},"hgnc":{"alias_symbol":[],"prev_symbol":["MEF2BNB"]},"alphafold":{"accession":"Q96FH0","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96FH0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96FH0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96FH0-F1-predicted_aligned_error_v6.png","plddt_mean":92.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=BORCS8","jax_strain_url":"https://www.jax.org/strain/search?query=BORCS8"},"sequence":{"accession":"Q96FH0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96FH0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96FH0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96FH0"}},"corpus_meta":[{"pmid":"26859814","id":"PMC_26859814","title":"Obsessive-compulsive symptoms in a large population-based twin-family sample are predicted by clinically based polygenic scores and by genome-wide SNPs.","date":"2016","source":"Translational psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/26859814","citation_count":53,"is_preprint":false},{"pmid":"25271210","id":"PMC_25271210","title":"Identification of genes whose expression is altered by obesity throughout the arterial tree.","date":"2014","source":"Physiological genomics","url":"https://pubmed.ncbi.nlm.nih.gov/25271210","citation_count":23,"is_preprint":false},{"pmid":"38128568","id":"PMC_38128568","title":"Biallelic BORCS8 variants cause an infantile-onset neurodegenerative disorder with altered lysosome dynamics.","date":"2024","source":"Brain : a journal of neurology","url":"https://pubmed.ncbi.nlm.nih.gov/38128568","citation_count":19,"is_preprint":false},{"pmid":"38134459","id":"PMC_38134459","title":"Weighted single-step GWAS identified candidate genes associated with carcass traits in a Chinese yellow-feathered chicken population.","date":"2023","source":"Poultry science","url":"https://pubmed.ncbi.nlm.nih.gov/38134459","citation_count":13,"is_preprint":false},{"pmid":"41887224","id":"PMC_41887224","title":"BLOC1S1 variants cause lysosomal and autophagic defects resulting in a hypomyelinating leukodystrophy with epileptic encephalopathy.","date":"2026","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/41887224","citation_count":1,"is_preprint":false},{"pmid":"40791729","id":"PMC_40791729","title":"BLOC1S1 variants cause lysosomal and autophagic defects resulting in a hypomyelinating leukodystrophy with epileptic encephalopathy.","date":"2025","source":"medRxiv : the preprint server for health sciences","url":"https://pubmed.ncbi.nlm.nih.gov/40791729","citation_count":0,"is_preprint":false},{"pmid":"42103727","id":"PMC_42103727","title":"The ISG Atlas: a loss-of-function analysis characterizes antiviral properties of interferon stimulated genes.","date":"2026","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/42103727","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":6423,"output_tokens":988,"usd":0.017045,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":7489,"output_tokens":1782,"usd":0.040997,"stage2_stop_reason":"end_turn"},"total_usd":0.058042,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2024,\n      \"finding\": \"BORCS8 is a subunit of the BLOC-one-related complex (BORC) that associates with the cytosolic face of lysosomes and promotes anterograde transport of lysosomes toward the cell periphery in non-neuronal cells and toward the distal axon in neurons by sequentially recruiting the small GTPase ARL8 and kinesin-1 and -3 microtubule motors. Disease-associated missense variants (p.Ser29Pro, p.Ser42Pro, p.Thr66Pro) are expressed at normal levels but show reduced assembly with other BORC subunits and reduced ability to drive peripheral lysosome distribution; a frameshift variant (p.Asn26Trpfs*51) is expressed at lower levels and is completely incapable of assembling with BORC subunits or promoting lysosome distribution.\",\n      \"method\": \"Heterologous transfection rescue assays in cultured cells (lysosome distribution quantification, co-assembly assays); zebrafish borcs8 knockout for in vivo validation\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (transfection rescue, co-assembly, lysosome distribution imaging, zebrafish KO), variant-level mechanistic dissection, peer-reviewed\",\n      \"pmids\": [\"38128568\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"BORCS8 mediates acidification of early endosomes during viral entry, a process that facilitates degradation of virus particles; loss-of-function of BORCS8 identified in a systematic arrayed screen modulates SARS-CoV-2 infection.\",\n      \"method\": \"Arrayed loss-of-function screen (siRNA/shRNA) against 285 ISGs across eight viruses; mechanistic follow-up demonstrating early endosome acidification\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — pan-ISG screen with mechanistic follow-up on endosome acidification for BORCS8 specifically, but single study and limited orthogonal validation described in abstract\",\n      \"pmids\": [\"42103727\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"BORCS8 variants in the context of BORC dysfunction impair anterograde lysosome transport and autophagy, establishing that BORCS8/BORC function is required for lysosomal dynamics and autophagy in non-neuronal cells and iPSC-derived neurons (contextual finding from BLOC1S1 study confirming BORCS8-BORC pathway).\",\n      \"method\": \"BLOC1S1-KO functional studies with parallel reference to BORCS8 disease variants; lysosome transport assays, autophagy assays in iPSC-derived neurons\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO plus iPSC-derived neuron assays, but BORCS8 is referenced indirectly as a comparator; peer-reviewed\",\n      \"pmids\": [\"41887224\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"BORCS8 is a subunit of the BORC multiprotein complex that localizes to the cytosolic face of lysosomes, where it promotes anterograde lysosomal transport toward the cell periphery (and distal axon in neurons) by recruiting ARL8 and kinesin motors; it also mediates early endosome acidification to facilitate degradation of endocytosed cargo including viral particles, and loss-of-function variants that disrupt BORC assembly and lysosome dynamics cause an infantile-onset neurodegenerative disorder.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"BORCS8 is a subunit of the BLOC-one-related complex (BORC) that associates with the cytosolic face of lysosomes and drives their anterograde transport toward the cell periphery in non-neuronal cells and toward the distal axon in neurons, acting by sequentially recruiting the small GTPase ARL8 and kinesin-1 and -3 microtubule motors [#0]. Within this pathway BORCS8/BORC function is required for lysosomal dynamics and autophagy in both non-neuronal cells and iPSC-derived neurons [#2]. BORCS8 additionally mediates acidification of early endosomes during viral entry, facilitating degradation of virus particles and thereby modulating SARS-CoV-2 infection [#1]. Disease-associated missense variants (p.Ser29Pro, p.Ser42Pro, p.Thr66Pro) are expressed normally but assemble poorly with other BORC subunits and fail to drive peripheral lysosome distribution, while a frameshift variant (p.Asn26Trpfs*51) is expressed at reduced levels and cannot assemble with BORC or promote lysosome distribution, causing an infantile-onset neurodegenerative disorder [#0].\",\n  \"teleology\": [\n    {\n      \"year\": 2024,\n      \"claim\": \"Established that BORCS8 is a functional BORC subunit whose disease variants impair complex assembly and lysosome positioning, linking molecular defects to an inherited neurodegenerative disorder.\",\n      \"evidence\": \"Heterologous transfection rescue and co-assembly assays in cultured cells with lysosome distribution imaging; zebrafish borcs8 knockout for in vivo validation\",\n      \"pmids\": [\"38128568\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis for how the Ser/Thr-to-Pro substitutions disrupt BORC assembly is not resolved\",\n        \"Direct biochemical demonstration of ARL8/kinesin recruitment by BORCS8 specifically is not isolated from the complex\",\n        \"Mechanism connecting impaired lysosome distribution to neuronal degeneration is not defined\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Extended BORCS8 function beyond lysosome positioning to early endosome acidification during viral entry, implicating it in antiviral degradation of internalized particles.\",\n      \"evidence\": \"Arrayed siRNA/shRNA loss-of-function screen across eight viruses with mechanistic follow-up on early endosome acidification\",\n      \"pmids\": [\"42103727\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single study with limited orthogonal validation of the acidification mechanism\",\n        \"How a BORC/lysosome-positioning subunit controls early endosome pH is not mechanistically explained\",\n        \"Whether the antiviral role depends on the same BORC assembly required for lysosome transport is unknown\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Confirmed within a BLOC1S1-focused study that the BORCS8/BORC pathway is required for anterograde lysosome transport and autophagy in iPSC-derived neurons, reinforcing its neuronal relevance.\",\n      \"evidence\": \"BLOC1S1-KO functional studies with lysosome transport and autophagy assays in iPSC-derived neurons, referencing BORCS8 disease variants as comparators\",\n      \"pmids\": [\"41887224\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"BORCS8 is referenced indirectly as a comparator rather than directly perturbed in this study\",\n        \"The contribution of BORCS8 versus other BORC subunits to the autophagy defect is not separated\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the same BORCS8/BORC machinery coordinates lysosome positioning, autophagy, and early endosome acidification, and how its disruption produces neurodegeneration, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No structural model of BORCS8 within the assembled BORC complex\",\n        \"Mechanistic link between lysosome mispositioning and neuronal cell death undefined\",\n        \"Reconciliation of the endosomal acidification role with the established lysosome-transport role\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [2]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"complexes\": [\"BORC\"],\n    \"partners\": [\"ARL8\", \"BLOC1S1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":4,"faith_pct":100.0}}