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Showing BORCS5LOH12CR1 is a alias.

BORCS5

BLOC-1-related complex subunit 5 · UniProt Q969J3

Length
196 aa
Mass
22.2 kDa
Annotated
2026-06-09
13 papers in source corpus 7 papers cited in narrative 8 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

BORCS5 is a structurally essential subunit of the octameric BORC complex that drives kinesin-1-dependent anterograde movement of lysosomes toward the cell periphery (PMID:42012897, PMID:36717601). The complex is built from two intertwined tetramers, and within BORCS5 a pH-sensitive histidine residue contributes to regulating BORC formation and function (PMID:41557793). Protein-truncating BORCS5 variants lower BORCS5 protein levels and impair BORC assembly, establishing that BORCS5 is required for complex integrity, whereas missense variants leave assembly and anterograde transport intact (PMID:42012897, PMID:40385417). Loss of BORCS5 causes perinuclear lysosomal clustering and blocks lysosomal axonal trafficking in iPSC-derived forebrain neurons (PMID:42012897); in macrophages, BORC- and kinesin-1-dependent peripheral positioning counteracts autophagy evasion by M. tuberculosis by promoting lysosomal delivery to bacterial phagosomes (PMID:36717601). Beyond organelle positioning, both loss-of-function and missense variants reduce total lysosomal proteolysis, lower glucocerebrosidase and cathepsin B activity, and cause accumulation of multilamellar bodies, revealing a role for BORCS5 in lysosomal hydrolytic function (PMID:42012897, PMID:40385417). Separately, BORCS5 acts as a regulator of the G1/S cell cycle checkpoint via p16INK4a and p21WAF1/CIP1, and its disruption through chromosomal fusion events (LMO3-BORCS5, BORCS5-ETV6) contributes to oncogenesis (PMID:29879888, PMID:31488873).

Mechanistic history

Synthesis pass · year-by-year structured walk · 5 steps
  1. 2018 Medium

    Established a cell-cycle role for BORCS5 by showing it gates the G1/S transition, the first functional readout linking the gene to proliferation control.

    Evidence Reciprocal siRNA knockdown and overexpression in colorectal cancer lines with cell cycle and p16/p21 western readouts

    PMID:29879888

    Open questions at the time
    • Does not connect the cell-cycle phenotype to BORC-dependent lysosomal function
    • Mechanism by which BORCS5 controls p16INK4a/p21WAF1 expression unresolved
  2. 2019 Medium

    Addressed whether BORCS5 disruption is oncogenic by characterizing fusion genes that interrupt the locus, implicating loss of intact BORCS5 in tumor formation.

    Evidence LMO3-BORCS5 in vivo tumor formation in NIH-3T3 cells and BORCS5-ETV6 fusion knockdown in a gastric cancer line

    PMID:31222839 PMID:31488873

    Open questions at the time
    • Cannot separate the contribution of the partner gene from loss of BORCS5
    • ETV6 fusion validated in only a single cell line with one functional method
    • No mechanistic link to BORCS5's lysosomal or cell-cycle activities
  3. 2023 Medium

    Placed BORCS5 in a defined molecular pathway by showing the BORC subunits work through kinesin-1 to position lysosomes peripherally, with a physiological consequence for innate immunity.

    Evidence siRNA knockdown of BORCS5-8 and kinesin-1/3 in macrophages with phagosome-lysosome fusion and positioning assays

    PMID:36717601

    Open questions at the time
    • Did not isolate BORCS5 from the other co-depleted subunits
    • Single study with knockdown rather than genetic loss
  4. 2025 High

    Defined BORCS5 as structurally essential to BORC and dissected genotype-phenotype: truncating variants destabilize the complex and block anterograde lysosome trafficking, while missense variants spare transport but still impair lysosomal hydrolytic function.

    Evidence iPSC-derived neurons, zebrafish KO, exome sequencing, lysosomal imaging, hydrolase/proteolysis assays, and BORC assembly readouts in patient cells

    PMID:40385417 PMID:42012897

    Open questions at the time
    • Mechanism by which missense variants impair hydrolase activity without disrupting transport is undefined
    • How perinuclear clustering causes reduced proteolysis not mechanistically resolved
  5. 2026 High

    Resolved the architecture of human BORC as two intertwined tetramers and identified interfacial and pH-sensitive residues in BORCS5 governing complex integrity.

    Evidence Cross-linking mass spectrometry of endogenous human BORC, C. elegans structure determination, and interfacial residue mutagenesis

    PMID:41557793

    Open questions at the time
    • Functional role of the pH-sensitive histidine not tested in cells
    • Human structure inferred partly from C. elegans complex

Open questions

Synthesis pass · forward-looking unresolved questions
  • How BORCS5 mechanistically links anterograde lysosome positioning to lysosomal hydrolase activity, and whether its cell-cycle/oncogenic roles are downstream of BORC function, remain unresolved.
  • No mechanism connecting lysosome positioning to hydrolase regulation
  • Cell-cycle role not integrated with lysosomal function
  • Direct physical partners of BORCS5 beyond BORC subunits not defined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005198 structural molecule activity 2
Localization
GO:0005764 lysosome 2
Pathway
R-HSA-9609507 Protein localization 2
Complex memberships
BORC

Evidence

Reading pass · 8 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2025 BORCS5 encodes a subunit of the BORC complex required for kinesin-dependent anterograde (peripheral) movement of lysosomes; loss-of-function variants (protein-truncating) cause perinuclear lysosomal clustering and impaired lysosomal axonal trafficking in iPSC-derived forebrain neurons, whereas missense variants do not cause this trafficking defect. Patient-derived cell studies (iPSC-derived neurons), zebrafish Borcs5 KO, whole-exome sequencing, lysosomal localization imaging The Journal of clinical investigation High 42012897
2025 BORCS5 is required for lysosomal function beyond anterograde transport: both loss-of-function and missense BORCS5 variants are associated with reduced total lysosomal proteolysis, reduced activity of lysosomal hydrolases glucocerebrosidase and cathepsin B, and accumulation of multilamellar bodies, revealing a role for BORCS5 in regulating lysosomal hydrolytic function. Lysosomal hydrolase activity assays (glucocerebrosidase, cathepsin B), proteolysis assays, electron microscopy of multilamellar bodies in patient-derived cells The Journal of clinical investigation High 40385417 42012897
2025 Loss-of-function (protein-truncating) BORCS5 variants, but not missense variants, result in lower BORCS5 protein expression and impaired BORC complex assembly, demonstrating that BORCS5 is structurally essential for BORC integrity. Western blot (protein expression), co-immunoprecipitation or co-fractionation for BORC assembly assessment in patient-derived cells medRxiv Medium 40385417 42012897
2026 The octameric BORC complex is formed by two intertwined tetramers; cross-linking mass spectrometry of endogenous human BORC validates this architecture, and specific interfacial residues are essential for complex integrity and lysosomal transport. BORCS5 contains a pH-sensitive histidine residue proposed to regulate BORC formation and function. Cross-linking mass spectrometry of endogenous complexes, C. elegans BORC structure determination, interfacial residue mutagenesis Proceedings of the National Academy of Sciences of the United States of America High 41557793
2023 BORCS5 (as part of BORC components BORCS5-8) promotes peripheral lysosome positioning via Kinesin-1; depletion of BORCS5-8 or Kinesin-1 (but not Kinesin-3) in macrophages reverts autophagy evasion by M. tuberculosis Beijing strain, increases lysosomal delivery to bacterial phagosomes, and causes augmented perinuclear lysosomal relocation. siRNA knockdown of BORCS5-8 and Kinesin-1/3 in macrophages, lysosomal delivery assays to phagosomes, lysosomal positioning imaging Scientific reports Medium 36717601
2018 BORCS5 (LOH12CR1) knockdown in colorectal cancer cell lines promotes cell proliferation and accelerates G1/S cell cycle transition through downregulation of p16INK4a and p21WAF1/CIP1; ectopic overexpression produces the opposite effects, placing BORCS5 as a regulator of the G1/S checkpoint. siRNA knockdown and ectopic overexpression in colorectal cancer cell lines, cell cycle analysis (flow cytometry), colony formation assay, western blot for p16INK4a and p21WAF1/CIP1 Current molecular medicine Medium 29879888
2019 The LMO3-BORCS5 fusion oncogene (disrupting BORCS5) increases proliferation, decreases apoptosis-related gene expression and treatment sensitivity, downregulates differentiation genes, and induces tumors in NIH-3T3 mouse fibroblasts in vivo, suggesting that disruption of intact BORCS5 contributes to oncogenesis. In vitro proliferation and apoptosis assays, gene expression profiling, in vivo tumor formation in NIH-3T3 cells Oncogene Medium 31488873
2019 A BORCS5-ETV6 fusion gene identified in scirrhous-type gastric cancer cell line OCUM-9 possesses oncogenic activity; suppression of its message partially inhibits cell growth. RNA sequencing, whole exome sequencing, siRNA knockdown of fusion transcript, cell growth assay Cancer science Low 31222839

Source papers

Stage 0 corpus · 13 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2002 A detailed transcriptional map of the chromosome 12p12 tumour suppressor locus. European journal of human genetics : EJHG 36 11896457
2004 Mutational and expression analysis of the chromosome 12p candidate tumor suppressor genes in pre-B acute lymphoblastic leukemia. Leukemia 31 15284860
2021 Integrative omics provide biological and clinical insights into acute respiratory distress syndrome. Intensive care medicine 30 34032881
2019 Comparative proteomic analysis of high- and low-fertile buffalo bull spermatozoa for identification of fertility-associated proteins. Reproduction in domestic animals = Zuchthygiene 30 30820981
2019 Identification of candidates for driver oncogenes in scirrhous-type gastric cancer cell lines. Cancer science 9 31222839
2019 Newly identified LMO3-BORCS5 fusion oncogene in Ewing sarcoma at relapse is a driver of tumor progression. Oncogene 9 31488873
2023 BORC complex specific components and Kinesin-1 mediate autophagy evasion by the autophagy-resistant Mycobacterium tuberculosis Beijing strain. Scientific reports 6 36717601
2025 Pathogenic variants in BORCS5 Cause a Spectrum of Neurodevelopmental and Neurodegenerative Disorders with Lysosomal Dysfunction. medRxiv : the preprint server for health sciences 2 40385417
2018 LOH12CR1 is a Novel Tumor Suppressor Inhibiting Tumor Growth Through Deregulation of G1/S Checkpoint in Human Colorectal Carcinoma. Current molecular medicine 2 29879888
2026 BORC assemblies integrate BLOC-1 subunits to diversify endosomal trafficking functions. Proceedings of the National Academy of Sciences of the United States of America 1 41557793
2024 Whole-genome resequencing reveals genetic differentiation and selection signatures among wild, local and commercial duck populations. Animal bioscience 1 40336248
2026 Pathogenic variants in BORCS5 cause a spectrum of neurodevelopmental and neurodegenerative disorders with lysosomal dysfunction. The Journal of clinical investigation 0 42012897
2025 Neuroaxonal Dystrophy With Osteopetrosis Associated With a Novel Biallelic Nonsense Homozygous Variant in BORCS5. American journal of medical genetics. Part A 0 40621786

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