Affinage

ARPC5L

Actin-related protein 2/3 complex subunit 5-like protein · UniProt Q9BPX5

Round 2 corrected
Length
153 aa
Mass
16.9 kDa
Annotated
2026-04-28
41 papers in source corpus 9 papers cited in narrative 9 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

ARPC5L is an isoform-specific subunit of the Arp2/3 complex that confers stimulus- and compartment-selective actin polymerization activity distinct from its paralog ARPC5. In CD4 T cells, ARPC5L specifically drives nuclear actin polymerization downstream of TCR-induced calcium–calmodulin–N-WASP signaling, whereas ARPC5 controls cytoplasmic actin dynamics and DNA-replication-stress responses (PMID:37162507). At actin branch junctions, ARPC5L stabilizes ArpC1 and regulates Ena/VASP positioning to shape protrusion architecture and cell migration (PMID:36662867), and it binds force-exposed cryptic sites in the talin 1 rod domain to couple integrin mechanosensing to extracellular matrix remodeling and vascular mechanical homeostasis in vivo (PMID:39167642, PMID:39344156). ARPC5L is transcriptionally induced by cooperating oncogenic PI3K and KMT2D loss and is required for the resulting Arp2/3-dependent single-cell migration persistence (PMID:38786098).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2014 Medium

    Identification of ARPC5L as a target of minor spliceosome processing established that its expression depends on U12-type intron splicing and implicated it in growth hormone–related endocrine biology.

    Evidence RNA-seq and RT-PCR of RNPC3-mutant patient cells showing aberrant ARPC5L splicing

    PMID:24480542

    Open questions at the time
    • Whether aberrant ARPC5L splicing causally contributes to pituitary dysfunction versus being a bystander effect is unresolved
    • No direct measurement of ARPC5L protein levels in affected tissues
  2. 2014 Low

    Phosphoproteomic profiling first linked ARPC5L phosphorylation status to Src kinase signaling and migration/adhesion phenotypes, raising the possibility that post-translational modification regulates ARPC5L-containing Arp2/3 complexes.

    Evidence Gel-based phosphoproteomics of Src-inhibitor-treated SaOS-2 osteosarcoma cells with migration/adhesion assays

    PMID:24615350

    Open questions at the time
    • No site-directed mutagenesis or identification of specific phospho-residue; no writer/eraser validation
    • Single cell line, single inhibitor
    • Phosphorylation could be indirect via other Arp2/3 subunits or adaptor proteins
  3. 2016 Low

    Cross-linking mass spectrometry placed ARPC5L within the intact seven-subunit Arp2/3 complex that interacts with protein kinase D2 at both cytosolic and Golgi-enriched compartments, suggesting ARPC5L-containing complexes operate at multiple subcellular sites.

    Evidence Affinity enrichment with XL-MS in cytosolic and Golgi fractions

    PMID:27559607

    Open questions at the time
    • No reciprocal validation specific to ARPC5L; PKD2 interaction detected at the complex level, not subunit-resolved
    • Functional consequence of the PKD2–ARPC5L-containing complex interaction not tested
  4. 2023 High

    Structural and cell-biological dissection of Arp2/3 branch junctions revealed that ARPC5L stabilizes ArpC1 at branches and controls Ena/VASP positioning at the leading edge, establishing the first mechanistic basis for isoform-specific effects on migration architecture.

    Evidence Cryo-electron tomography of branch junctions, TIRF/FRAP imaging, reverse genetics (KO/KD of ArpC5 vs ArpC5L), VASP localization analysis

    PMID:36662867

    Open questions at the time
    • Structural determinants within ARPC5L versus ARPC5 that explain differential ArpC1 stabilization are not resolved at atomic level
    • Whether Ena/VASP regulation by ARPC5L is direct or mediated by altered network geometry is unclear
  5. 2023 High

    Isoform-selective knockdown in CD4 T cells demonstrated that ARPC5L is specifically required for nuclear actin polymerization downstream of TCR–calcium–calmodulin–N-WASP signaling, while ARPC5 handles cytoplasmic actin and replication-stress responses, establishing compartment- and stimulus-specific routing of Arp2/3 activity.

    Evidence siRNA knockdown of ARPC5 vs ARPC5L; live-cell imaging of nuclear/cytoplasmic actin; pharmacological inhibition of calmodulin and N-WASP; TCR activation and replication stress stimuli

    PMID:37162507

    Open questions at the time
    • Mechanism of ARPC5L nuclear import or retention is not defined
    • How heterogeneous ARPC5L expression across T cells affects functional outcomes is unexplored
    • Whether ARPC5L drives nuclear actin in non-T cell contexts is untested
  6. 2024 High

    Biochemical and in vivo studies showed that ARPC5L binds a force-exposed cryptic site in the talin 1 rod domain (R1–R2 interface), linking integrin mechanosensing to Arp2/3-dependent cytoskeletal remodeling, cell spreading, and extracellular matrix mechanical homeostasis including aortic collagen architecture and rupture resistance.

    Evidence Co-IP/pull-down with talin mutants; knock-in mice with open R1-R2 talin; AFM and tensile testing of aortic tissue; DNA-based molecular clamp reconstitution

    PMID:39167642 PMID:39344156

    Open questions at the time
    • Whether ARPC5L binds talin as a free subunit or as part of the assembled Arp2/3 complex is not resolved
    • The specific ARPC5L residues mediating talin binding are not mapped
    • Whether ARPC5 shares this mechanosensitive talin interaction is not tested
  7. 2024 Medium

    Oncogenic PI3K cooperating with KMT2D loss transcriptionally induces ARPC5L, and ARPC5L depletion fully abolishes the resulting single-cell migration persistence, placing ARPC5L as a critical effector of an oncogene-driven migration program.

    Evidence PI3K-H1047R knock-in + KMT2D shRNA in MCF10A cells; siRNA depletion of ARPC5L; single-cell tracking; RNA-seq

    PMID:38786098

    Open questions at the time
    • Whether ARPC5L induction is a direct transcriptional target of altered chromatin or secondary to signaling changes is not determined
    • Generalizability beyond MCF10A cells not tested
  8. 2024 Medium

    Hematopoietic-specific Arpc5l knockout in mice showed that ARPC5L-containing Arp2/3 complexes are dispensable for macrophage phagocytosis and intestinal host-microbiota defense, functions that require ARPC5-containing complexes, sharpening the picture of non-overlapping isoform roles in vivo.

    Evidence Conditional KO of Arpc5l in mouse hematopoietic system; intestinal histopathology; bacterial phagocytosis/killing assays (preprint)

    PMID:bio_10.1101_2024.07.18.604111

    Open questions at the time
    • Preprint; not yet peer-reviewed
    • Positive biological role of ARPC5L in hematopoietic cells (beyond nuclear actin in T cells) remains unknown
    • Whether ARPC5L loss affects adaptive immune functions other than T cell nuclear actin is unexplored

Open questions

Synthesis pass · forward-looking unresolved questions
  • Key unresolved questions include the structural basis for ARPC5L versus ARPC5 selectivity in complex assembly and nuclear targeting, the identity of the ARPC5L binding interface on talin and whether it engages talin as a monomer or assembled complex subunit, and the in vivo consequences of ARPC5L loss in non-hematopoietic tissues such as the cardiovascular system.
  • No atomic-resolution structure of ARPC5L in complex with talin or within a branch junction
  • Nuclear import/retention mechanism for ARPC5L-containing Arp2/3 complexes not defined
  • Cardiovascular phenotype of ARPC5L loss-of-function not tested in knockout models

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0008092 cytoskeletal protein binding 3 GO:0005198 structural molecule activity 2
Localization
GO:0005856 cytoskeleton 3 GO:0005829 cytosol 2 GO:0005634 nucleus 1
Pathway
R-HSA-162582 Signal Transduction 3 R-HSA-1474244 Extracellular matrix organization 2 R-HSA-168256 Immune System 1
Partners
ARPC1AARPC1BTLN1VASPWASL
Complex memberships
Arp2/3 complex

Evidence

Reading pass · 9 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2014 ARPC5L contains a U12-type intron and its pre-mRNA is aberrantly spliced in patient cells harboring biallelic loss-of-function mutations in RNPC3, a minor spliceosome component required for U11/U12 snRNP formation. Defective ARPC5L transcripts were identified as candidate contributors to somatotroph-restricted dysfunction in isolated familial growth hormone deficiency. RNA sequencing and RT-PCR analysis of patient-derived cells; minor spliceosome U11/U12 di-snRNP formation assays EMBO Molecular Medicine Medium 24480542
2014 ARPC5L (a subunit of the Arp2/3 complex) is dephosphorylated in human osteosarcoma SaOS-2 cells treated with the Src inhibitor SI-83, and this dephosphorylation is accompanied by dramatic impairment of cell migration and adhesion, suggesting ARPC5L phosphorylation status links Src kinase activity to cytoskeletal dynamics and metastatic potential. Gel-based phosphoproteomics of SI-83-treated SaOS-2 cells; migration and adhesion functional assays Molecular BioSystems Low 24615350
2016 ARPC5L was identified as a component of the intact seven-subunit Arp2/3 complex that directly interacts with human protein kinase D2 (PKD2), detected in both cytosolic and Golgi-enriched subcellular fractions, via chemical cross-linking/mass spectrometry affinity enrichment. Affinity enrichment combined with chemical cross-linking/mass spectrometry (XL-MS) in cytosolic and Golgi fractions Journal of Proteome Research Low 27559607
2023 ARPC5L specifically drives nuclear actin polymerization upon TCR stimulation in CD4 T cells, acting downstream of nuclear calcium-calmodulin signaling and N-WASP, whereas ARPC5 (the paralog) is required for cytoplasmic actin dynamics. Nuclear actin polymerization triggered by DNA replication stress specifically requires ARPC5 but not ARPC5L, demonstrating isoform-specific routing of Arp2/3 activity to distinct physiological stimuli. ARPC5L is heterogeneously expressed across individual CD4 T cells. siRNA knockdown of ARPC5 vs. ARPC5L; live-cell imaging of nuclear and cytoplasmic actin dynamics; pharmacological inhibition of calmodulin and N-WASP; TCR activation and DNA replication stress stimuli eLife High 37162507
2023 ArpC5L incorporation into the Arp2/3 complex determines the structural stability of ArpC1 at branch junctions and influences protrusion characteristics and actin network ultrastructure during cell migration. ArpC5L isoform-specific effects on actin assembly level are mediated through differential positioning of Ena/VASP family actin filament elongators at the cell leading edge, placing ArpC5 isoforms and Ena/VASP in a common signaling pathway controlling cell migration. Reverse genetics (knockout/knockdown of ArpC5 vs. ArpC5L); cellular structural biology (cryo-electron tomography of branch junctions); TIRF/FRAP imaging; VASP localization analysis Science Advances High 36662867
2024 ARPC5L binds to a mechanosensitive site between helix bundles R1 and R2 of the talin 1 rod domain. Mutations that open the R1-R2 interface promote ARPC5L binding, increase cell spreading and tension on compliant substrates, and alter tissue mechanical homeostasis in vivo (ascending aortas show reduced fibrillar collagen, lower axial stiffness, and rupture at lower pressure in knock-in mice). ARPC5L thus mediates the downstream effect of talin mechanosensing on ECM remodeling. Co-immunoprecipitation/pull-down with talin mutants; mouse knock-in models; atomic force microscopy/tensile testing of aortic tissue; confocal imaging of fibrillar collagen; cell spreading assays on compliant substrates Science Advances High 39167642
2024 Tension applied to a fragment of the talin rod domain using a DNA-based molecular clamp induces binding of ARPC5L (alongside vinculin) to cryptic sites within the talin structure, demonstrating that ARPC5L recognition of talin is force-dependent and occurs at mechanically exposed cryptic binding sites. DNA-based molecular clamp applying defined tension to talin rod domain fragment; pull-down assays; negative-stain electron microscopy ACS Nano Medium 39344156
2024 Combined activation of PI 3-kinase (H1047R mutation) and inactivation of the histone methyltransferase KMT2D in MCF10A mammary epithelial cells synergistically induces ARPC5L gene expression. ARPC5L depletion fully abolishes the enhanced single-cell migration persistence conferred by this double mutation, placing ARPC5L as an essential downstream effector of an Arp2/3-dependent migration program driven by oncogenic PI 3-kinase and KMT2D loss. Stable cell line engineering (PI3K H1047R knock-in + KMT2D shRNA); siRNA depletion of ARPC5L; single-cell migration tracking; RNA-seq for ARPC5L expression quantification Cells Medium 38786098
2024 Loss of Arpc5l (the ARPC5L isoform) in the murine hematopoietic system, unlike loss of Arpc5, does not cause intestinal inflammation or impaired macrophage phagocytosis of intracellular bacteria, demonstrating that ARPC5L-containing Arp2/3 complexes are dispensable for mononuclear phagocyte function and host-microbiota homeostasis — these functions are specifically dependent on ARPC5-containing complexes. Hematopoietic-specific conditional knockout of Arpc5l in mice; intestinal histopathology; bacterial phagocytosis and killing assays in macrophages bioRxivpreprint Medium bio_10.1101_2024.07.18.604111

Source papers

Stage 0 corpus · 41 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2006 Global, in vivo, and site-specific phosphorylation dynamics in signaling networks. Cell 2861 17081983
2012 Insights into RNA biology from an atlas of mammalian mRNA-binding proteins. Cell 1718 22658674
2005 A human protein-protein interaction network: a resource for annotating the proteome. Cell 1704 16169070
2002 Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences. Proceedings of the National Academy of Sciences of the United States of America 1479 12477932
2015 The BioPlex Network: A Systematic Exploration of the Human Interactome. Cell 1118 26186194
2017 Architecture of the human interactome defines protein communities and disease networks. Nature 1085 28514442
2015 A human interactome in three quantitative dimensions organized by stoichiometries and abundances. Cell 1015 26496610
2020 A reference map of the human binary protein interactome. Nature 849 32296183
2003 Complete sequencing and characterization of 21,243 full-length human cDNAs. Nature genetics 754 14702039
2007 Large-scale mapping of human protein-protein interactions by mass spectrometry. Molecular systems biology 733 17353931
2021 Dual proteome-scale networks reveal cell-specific remodeling of the human interactome. Cell 705 33961781
2012 A census of human soluble protein complexes. Cell 689 22939629
2011 Phylogenetic-based propagation of functional annotations within the Gene Ontology consortium. Briefings in bioinformatics 656 21873635
2008 Large-scale proteomics and phosphoproteomics of urinary exosomes. Journal of the American Society of Nephrology : JASN 607 19056867
2011 Analysis of the myosin-II-responsive focal adhesion proteome reveals a role for β-Pix in negative regulation of focal adhesion maturation. Nature cell biology 490 21423176
2004 The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). Genome research 438 15489334
2022 OpenCell: Endogenous tagging for the cartography of human cellular organization. Science (New York, N.Y.) 432 35271311
2005 Diversification of transcriptional modulation: large-scale identification and characterization of putative alternative promoters of human genes. Genome research 409 16344560
2015 Panorama of ancient metazoan macromolecular complexes. Nature 407 26344197
2015 Proteome-wide profiling of protein assemblies by cross-linking mass spectrometry. Nature methods 370 26414014
2007 Functional specialization of beta-arrestin interactions revealed by proteomic analysis. Proceedings of the National Academy of Sciences of the United States of America 360 17620599
2021 A proximity-dependent biotinylation map of a human cell. Nature 339 34079125
2012 A high-throughput approach for measuring temporal changes in the interactome. Nature methods 273 22863883
2007 hORFeome v3.1: a resource of human open reading frames representing over 10,000 human genes. Genomics 222 17207965
2017 Optimized fragmentation schemes and data analysis strategies for proteome-wide cross-link identification. Nature communications 221 28524877
2010 MHC class II-associated proteins in B-cell exosomes and potential functional implications for exosome biogenesis. Immunology and cell biology 221 20458337
2015 ∆F508 CFTR interactome remodelling promotes rescue of cystic fibrosis. Nature 209 26618866
2011 Toward an understanding of the protein interaction network of the human liver. Molecular systems biology 207 21988832
2015 A deep proteomics perspective on CRM1-mediated nuclear export and nucleocytoplasmic partitioning. eLife 198 26673895
2011 Protein interactome reveals converging molecular pathways among autism disorders. Science translational medicine 180 21653829
2015 'Conceptualizing' the Endometrium: Identification of Conceptus-Derived Proteins During Early Pregnancy in Cattle. Biology of reproduction 82 25947061
2014 Defective minor spliceosome mRNA processing results in isolated familial growth hormone deficiency. EMBO molecular medicine 77 24480542
2023 ArpC5 isoforms regulate Arp2/3 complex-dependent protrusion through differential Ena/VASP positioning. Science advances 19 36662867
2023 ARPC5 isoforms and their regulation by calcium-calmodulin-N-WASP drive distinct Arp2/3-dependent actin remodeling events in CD4 T cells. eLife 19 37162507
2014 Proteomics and phosphoproteomics provide insights into the mechanism of action of a novel pyrazolo[3,4-d]pyrimidine Src inhibitor in human osteosarcoma. Molecular bioSystems 18 24615350
2024 Cellular stiffness sensing through talin 1 in tissue mechanical homeostasis. Science advances 11 39167642
2016 Protein Interaction Network of Human Protein Kinase D2 Revealed by Chemical Cross-Linking/Mass Spectrometry. Journal of proteome research 11 27559607
2024 DNA-Based Molecular Clamp for Probing Protein Interactions and Structure under Force. ACS nano 7 39344156
2024 Mechanosensing through talin 1 contributes to tissue mechanical homeostasis. bioRxiv : the preprint server for biology 2 38328095
2024 A DNA-based molecular clamp for probing protein interactions and structure under force. bioRxiv : the preprint server for biology 2 38895381
2024 PI 3-Kinase and the Histone Methyl-Transferase KMT2D Collaborate to Induce Arp2/3-Dependent Migration of Mammary Epithelial Cells. Cells 0 38786098