Affinage

CLEC14A

C-type lectin domain family 14 member A · UniProt Q86T13

Length
490 aa
Mass
51.6 kDa
Annotated
2026-04-28
22 papers in source corpus 15 papers cited in narrative 15 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

CLEC14A is an endothelial-selective transmembrane C-type lectin that promotes angiogenesis and maintains vascular homeostasis by mediating cell-cell adhesion, sprouting, and signaling balance through its C-type lectin-like domain (CTLD). The CTLD drives homophilic endothelial cell-cell contact and directly binds the extracellular matrix protein Multimerin-2 (MMRN2) via a long-loop region, as well as heparan sulfate with nanomolar affinity, to regulate sprouting angiogenesis and tumor vascularization; its ectodomain is proteolytically shed by the rhomboid protease RHBDL2 to generate a soluble fragment that inhibits tip-cell sprouting (PMID:25745997, PMID:28671670, PMID:31964714, PMID:26939791). CLEC14A forms a complex with VEGFR-3 and constrains VEGFR-2 signaling, such that its loss elevates VEGFR-2 activity, disrupts blood-brain barrier integrity, and worsens ischemic injury, while in bone it restrains type-H endothelial condensation and osteoblast maturation through MMRN2 binding (PMID:27991863, PMID:32019570, PMID:39394430). FLI1 directly activates CLEC14A transcription, and CLEC14A in turn promotes VEGFC expression, positioning it within a FLI1–CLEC14A–VEGFC angiogenic axis; additionally, CLEC14A binds HMGB1 in podocytes to suppress NF-κB/EGR1-driven inflammation (PMID:41548484, PMID:34107098).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2010 Medium

    The first mechanistic question—how CLEC14A influences endothelial behavior—was answered by showing that its CTLD mediates cell-cell adhesion and that knockdown impairs migration, filopodia, and tube formation, establishing CLEC14A as a pro-angiogenic adhesion molecule.

    Evidence Deletion mutant analysis and siRNA knockdown with migration and tube-formation assays in endothelial cells

    PMID:21095181

    Open questions at the time
    • Mechanism by which CTLD mediates homophilic adhesion not structurally resolved
    • Ligands of CTLD unknown at this stage
    • In vivo relevance not yet demonstrated
  2. 2011 Medium

    CLEC14A was validated as a tumor endothelial marker with in vivo relevance, as it promoted vascular development in zebrafish, extending its role beyond cultured cells to organismal angiogenesis.

    Evidence Overexpression, anti-CLEC14A antisera inhibition, zebrafish vascular development assay, immunohistochemistry of tumor vasculature

    PMID:21706054

    Open questions at the time
    • Molecular partners mediating in vivo angiogenesis unidentified
    • Mechanism of filopodia induction not defined
  3. 2013 Medium

    Domain-specific antibodies confirmed the CTLD as the key functional domain for cell-cell contact and showed that antibody cross-linking downregulates CLEC14A surface expression, revealing a potential feedback mechanism.

    Evidence Phage-display-derived anti-CTLD antibodies blocking migration, tube formation, and CTLD-CTLD interactions

    PMID:23644659

    Open questions at the time
    • Endocytic fate of cross-linked CLEC14A not characterized
    • Identity of CTLD binding partners still unknown
  4. 2015 High

    The question of what extracellular ligand CLEC14A engages was resolved by demonstrating direct binding to the ECM protein Multimerin-2, with antibody blockade of this interaction inhibiting sprouting angiogenesis and tumor growth in vivo.

    Evidence Reciprocal co-immunoprecipitation, pull-down, monoclonal antibody C4 blocking in aortic ring and tumor xenograft models

    PMID:25745997

    Open questions at the time
    • Binding site on CLEC14A not yet mapped
    • Downstream signaling triggered by MMRN2 binding undefined
  5. 2016 High

    Two major advances resolved how CLEC14A is regulated post-translationally and how it interfaces with VEGFR signaling: RHBDL2-mediated ectodomain shedding generates a soluble inhibitor of tip-cell sprouting, and CLEC14A forms a complex with VEGFR-3 to maintain VEGFR-2/VEGFR-3 signaling balance, with its loss shifting signaling toward excess VEGFR-2 activity.

    Evidence Site-directed mutagenesis mapping the RHBDL2 cleavage site, siRNA specificity, in vivo sponge implant (shedding); co-immunoprecipitation, CLEC14A-KO mouse, VEGFR-2 blockade epistasis (VEGFR-3 complex)

    PMID:26939791 PMID:27991863

    Open questions at the time
    • Signals controlling RHBDL2 activity toward CLEC14A unknown
    • Structural basis of CLEC14A–VEGFR-3 complex not determined
    • Whether shed ectodomain acts on VEGFR signaling not tested
  6. 2017 High

    The MMRN2-binding mechanism was refined: a long-loop region in the CTLD is required for MMRN2 binding; CLEC14A and CD93 compete for the same MMRN2 coiled-coil region whereas CD248 binds a distinct site, enabling simultaneous CLEC14A–MMRN2–CD248 complexes at endothelial-pericyte interfaces. Separately, HSP70-1A was identified as a CTLD ligand (residues 43–69) that drives ERK-dependent tube formation.

    Evidence Domain mutagenesis, competition assays, tissue co-localization (MMRN2); Co-IP, in vitro binding, competitive blocking, ERK phosphorylation assays (HSP70-1A)

    PMID:28671670 PMID:28878328

    Open questions at the time
    • Functional consequence of CLEC14A–CD93 competition for MMRN2 in vivo not established
    • Whether HSP70-1A binding and MMRN2 binding are mutually exclusive unknown
  7. 2020 High

    CLEC14A's glycosaminoglycan engagement was defined—the CTLD binds heparin 1:1 with nanomolar affinity and interacts with endothelial heparan sulfate and chondroitin sulfate E—and its physiological importance was extended to brain vascular integrity, as CLEC14A-KO mice exhibit increased BBB permeability and worsened ischemic stroke through VEGFR-2 hyperactivation.

    Evidence Heparin-affinity chromatography, mutagenesis-based site mapping, affinity measurements (GAG binding); siRNA knockdown, CLEC14A-KO mice, MCAO stroke model, Evans blue leakage, VEGFR-2 blockade (BBB)

    PMID:31964714 PMID:32019570

    Open questions at the time
    • Specific heparan sulfate epitope on endothelial surface not identified
    • Whether heparin binding and MMRN2 binding are coordinated not tested
    • Tight-junction regulation mechanism downstream of VEGFR-2 not fully dissected
  8. 2021 Medium

    CLEC14A's function was extended beyond endothelium to podocytes, where it directly binds HMGB1 and restrains HMGB1-mediated NF-κB/EGR1 inflammatory signaling; its deficiency worsens podocyte injury and proteinuria.

    Evidence Co-immunoprecipitation in podocytes, CLEC14A overexpression, CLEC14A-KO mice with adriamycin nephropathy

    PMID:34107098

    Open questions at the time
    • Binding site on CLEC14A for HMGB1 not mapped
    • Whether HMGB1 binding involves the CTLD not tested
    • Independent replication in a second nephropathy model lacking
  9. 2024 Medium

    In bone, CLEC14A on type-H endothelial cells restrains premature vascular condensation and osteoblast expansion through its interaction with MMRN2, broadening the CLEC14A–MMRN2 axis beyond tumor angiogenesis to skeletal development.

    Evidence Clec14a-/- mouse skeletal phenotyping, antibody-mediated blockade of Clec14a–Mmrn2 interaction recapitulating KO phenotype

    PMID:39394430

    Open questions at the time
    • Signaling pathway downstream of CLEC14A–MMRN2 in osteogenesis not identified
    • Contribution of CLEC14A–VEGFR-3 complex to bone phenotype not assessed
  10. 2026 Medium

    The transcriptional control of CLEC14A was resolved: the ETS factor FLI1 directly activates CLEC14A transcription, and CLEC14A in turn promotes VEGFC expression, establishing a FLI1–CLEC14A–VEGFC axis governing retinal angiogenesis.

    Evidence Dual-luciferase reporter assay for FLI1→CLEC14A, siRNA knockdown and overexpression rescue, in vivo choroidal neovascularization model

    PMID:41548484

    Open questions at the time
    • Mechanism by which CLEC14A regulates VEGFC expression (transcriptional vs. post-transcriptional) not defined
    • Whether FLI1 regulation is conserved in non-retinal vascular beds untested

Open questions

Synthesis pass · forward-looking unresolved questions
  • Key open questions remain: the structural basis of the CLEC14A–VEGFR-3 complex, the mechanism by which CLEC14A controls VEGFC expression, whether CLEC14A's multiple ligand interactions (MMRN2, heparan sulfate, HSP70-1A, HMGB1) are spatially or temporally segregated, and how RHBDL2 shedding is physiologically regulated.
  • No structural model of CLEC14A CTLD or its complexes available
  • Integration of shedding, VEGFR-3 complex formation, and MMRN2 binding in a unified signaling model lacking
  • Role of CLEC14A in human genetic disease not established

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098631 cell adhesion mediator activity 3 GO:0098772 molecular function regulator activity 2 GO:0008289 lipid binding 1
Localization
GO:0005886 plasma membrane 5 GO:0031012 extracellular matrix 2 GO:0005576 extracellular region 1
Pathway
R-HSA-1266738 Developmental Biology 3 R-HSA-162582 Signal Transduction 3 R-HSA-168256 Immune System 1
Partners
CD248CD93FLI1HMGB1HSPA1AMMRN2RHBDL2VEGFR3
Complex memberships
CLEC14A–VEGFR-3 complex

Evidence

Reading pass · 15 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2010 CLEC14A mediates endothelial cell-cell adhesion through its C-type lectin-like domain (CTLD), as demonstrated by deletion mutant analysis; knockdown in endothelial cells suppressed cell migratory activity, filopodial protrusion, and tube formation. Deletion mutant analysis, siRNA knockdown, cell migration and tube formation assays Biochemical and biophysical research communications Medium 21095181
2011 CLEC14A is a tumor endothelial marker that induces filopodia, facilitates endothelial migration and tube formation, and promotes vascular development in zebrafish; anti-CLEC14A antisera inhibited cell migration and tube formation. Overexpression, antisera inhibition assays, zebrafish developmental assay, immunohistochemistry Oncogene Medium 21706054
2013 The C-type lectin-like domain (CTLD) of CLEC14A is a key functional domain mediating cell-cell contact; antibodies targeting CTLD blocked endothelial cell migration, tube formation, and CTLD-CTLD interactions, and cross-linking downregulated CLEC14A surface expression. Phage display antibody selection, functional blocking assays, cell migration and tube formation assays Oncogene Medium 23644659
2015 CLEC14A binds directly to the extracellular matrix protein Multimerin-2 (MMRN2) via its extracellular region, as confirmed by pull-down and co-immunoprecipitation; this CLEC14A-MMRN2 interaction promotes sprouting angiogenesis and tumor growth, and blocking it with monoclonal antibody C4 inhibited endothelial sprouting and tumor growth in vivo. Pull-down, co-immunoprecipitation, monoclonal antibody blocking, aortic ring assay, in vivo tumor model Oncogene High 25745997
2016 CLEC14A ectodomain is cleaved (shed) by rhomboid-like protease RHBDL2, but not RHBDL1 or RHBDL3; site-directed mutagenesis identified the precise cleavage site; the shed ectodomain inhibits sprouting angiogenesis and binds to sprouting endothelial tip cells. Site-directed mutagenesis, siRNA knockdown of CLEC14A and RHBDL2, in vitro sprouting assays, in vivo sponge implant model, recombinant protein addition FASEB journal High 26939791
2016 CLEC14A forms a complex with VEGFR-3 in endothelial cells; CLEC14A knockout leads to reduced VEGFR-3 expression with concomitant increases in VEGFR-2 expression and downstream signaling, establishing CLEC14A as a regulator of VEGFR-2/VEGFR-3 balance in vascular homeostasis. Co-immunoprecipitation (complex formation), CLEC14A knockout mouse, Western blotting, in vivo vascular phenotype analysis, VEGFR-2 blockade epistasis The Journal of clinical investigation High 27991863
2017 CLEC14A, CD93, and CD248 all directly bind to Multimerin-2 (MMRN2); binding is dependent on a long-loop region in the C-type lectin domain and is abrogated by mutation within this domain; CLEC14A and CD93 bind the same non-glycosylated coiled-coil region of MMRN2, whereas CD248 binds a distinct non-competing region; CLEC14A and CD248 can simultaneously bind MMRN2, occurring at the endothelial-pericyte interface in human pancreatic cancer. Direct binding assays, mutagenesis (long-loop region), recombinant protein competition assays, co-localization in human tissue Oncogene High 28671670
2017 HSP70-1A interacts with CLEC14A specifically at amino acids 43–69 of the CTLD; this interaction mediates HSP70-1A-induced ERK phosphorylation and endothelial tube formation; competitive blocking of this region inhibits HSP70-1A-induced angiogenesis. Proteomic isolation, co-immunoprecipitation, in vitro binding assays, competitive blocking experiments, ERK phosphorylation assay, tube formation assay Scientific reports Medium 28878328
2018 The CLEC14A C-type lectin-like domain (CTLD) mediates endothelial cell-cell contact in angiogenesis; an antibody targeting CTLD directly inhibits this cell-cell contact and simultaneously downregulates CLEC14A surface expression, suppressing VEGF-dependent and tumor angiogenesis in vitro and in vivo. CDR grafting antibody generation, cell-cell contact assays, in vitro tube formation, in vivo tumor xenograft models Molecular oncology Medium 29316206
2019 In zebrafish, clec14a genetically interacts with ETS transcription factor Etv2 and with Vegfa signaling in vasculogenesis and angiogenesis; partial knockdown of Etv2 or Vegfaa shows synergistic inhibition with clec14a mutation, placing Clec14a in the same pathway as Etv2 and Vegf signaling. TALEN genome editing (zebrafish clec14a mutant), morpholino knockdown, genetic epistasis, vascular phenotype analysis BMC developmental biology Medium 30953479
2020 The C-type lectin domain of CLEC14A binds heparin in a 1:1 ratio with nanomolar affinity; molecular modeling and mutagenesis mapped the heparin-binding site within the CTLD; CLEC14A also physically interacts with endothelial heparan sulfate and chondroitin sulfate E but not neutral or sialylated oligosaccharides. Heparin-affinity chromatography (LPHAMS proteomics), molecular modeling, site-directed mutagenesis, binding affinity measurements The Journal of biological chemistry High 31964714
2020 CLEC14A deficiency increases BBB permeability by downregulating tight junctional proteins and activating VEGFR-2 signaling in endothelial cells; CLEC14A-KO mice show cerebral vascular leakage and exacerbated ischemic stroke injury that is suppressed by VEGFR-2 blockade, establishing CLEC14A as a negative regulator of VEGFR-2-driven BBB dysfunction. siRNA knockdown (in vitro FITC-dextran permeability, TEER assay), CLEC14A-KO mice, Evans blue/FITC-dextran leakage, MCAO stroke model, Western blotting, immunofluorescence Journal of neuroinflammation High 32019570
2021 CLEC14A directly binds HMGB1 in podocytes, inhibiting HMGB1 release and thereby suppressing HMGB1-mediated NF-κB and EGR1 signaling; CLEC14A deficiency exacerbates podocyte injury and proteinuria in adriamycin nephropathy mice. Co-immunoprecipitation (direct binding), CLEC14A overexpression in podocytes, CLEC14A-KO mice with adriamycin nephropathy model, Western blotting, NF-κB/EGR1 signaling assays FASEB journal Medium 34107098
2024 Clec14a on type-H endothelial cells orchestrates osteoblast maturation and bone formation via its interaction with Mmrn2; Clec14a-/- mice show premature condensation of type-H vasculature and expanded osteoblast distribution/activity; antibody-mediated blockade of the Clec14a-Mmrn2 interaction recapitulates the Clec14a-/- bone phenotype. Clec14a-/- mouse model, antibody-mediated blockade of Clec14a-Mmrn2 interaction, histological and immunofluorescence analysis of bone and vasculature Communications biology Medium 39394430
2026 FLI1 acts as a direct transcriptional activator of CLEC14A; CLEC14A in turn regulates VEGFC expression; knockdown of CLEC14A decreases VEGFC and impairs angiogenesis, while CLEC14A overexpression rescues DFMO-induced VEGFC downregulation, establishing a FLI1-CLEC14A-VEGFC regulatory axis in retinal endothelial angiogenesis. Dual-luciferase reporter assay (FLI1→CLEC14A), siRNA knockdown, CLEC14A overexpression, in vivo choroidal neovascularization mouse model Biochemical and biophysical research communications Medium 41548484

Source papers

Stage 0 corpus · 22 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2011 Identification and angiogenic role of the novel tumor endothelial marker CLEC14A. Oncogene 97 21706054
2017 Multimerin-2 is a ligand for group 14 family C-type lectins CLEC14A, CD93 and CD248 spanning the endothelial pericyte interface. Oncogene 68 28671670
2020 CLEC14A deficiency exacerbates neuronal loss by increasing blood-brain barrier permeability and inflammation. Journal of neuroinflammation 63 32019570
2015 Blocking CLEC14A-MMRN2 binding inhibits sprouting angiogenesis and tumour growth. Oncogene 45 25745997
2010 Clec14a is specifically expressed in endothelial cells and mediates cell to cell adhesion. Biochemical and biophysical research communications 45 21095181
2018 Activin receptor-like kinase 1 is associated with immune cell infiltration and regulates CLEC14A transcription in cancer. Angiogenesis 42 30132150
2018 Inhibition of VEGF-dependent angiogenesis and tumor angiogenesis by an optimized antibody targeting CLEC14a. Molecular oncology 35 29316206
2020 CAR T cells targeting tumor endothelial marker CLEC14A inhibit tumor growth. JCI insight 33 33004686
2019 Human muscle-derived CLEC14A-positive cells regenerate muscle independent of PAX7. Nature communications 33 31852888
2016 Sprouting angiogenesis is regulated by shedding of the C-type lectin family 14, member A (CLEC14A) ectodomain, catalyzed by rhomboid-like 2 protein (RHBDL2). FASEB journal : official publication of the Federation of American Societies for Experimental Biology 32 26939791
2020 Proteomics-based screening of the endothelial heparan sulfate interactome reveals that C-type lectin 14a (CLEC14A) is a heparin-binding protein. The Journal of biological chemistry 31 31964714
2013 Human antibodies targeting the C-type lectin-like domain of the tumor endothelial cell marker clec14a regulate angiogenic properties in vitro. Oncogene 30 23644659
2016 Carbohydrate-binding protein CLEC14A regulates VEGFR-2- and VEGFR-3-dependent signals during angiogenesis and lymphangiogenesis. The Journal of clinical investigation 29 27991863
2017 CLEC14a-HSP70-1A interaction regulates HSP70-1A-induced angiogenesis. Scientific reports 26 28878328
2021 CLEC14A protects against podocyte injury in mice with adriamycin nephropathy. FASEB journal : official publication of the Federation of American Societies for Experimental Biology 17 34107098
2020 An evaluation of the tumour endothelial marker CLEC14A as a therapeutic target in solid tumours. The journal of pathology. Clinical research 15 32696621
2018 Methylation of CLEC14A is associated with its expression and lung adenocarcinoma progression. Journal of cellular physiology 11 30191970
2019 Clec14a genetically interacts with Etv2 and Vegf signaling during vasculogenesis and angiogenesis in zebrafish. BMC developmental biology 9 30953479
2024 CLEC14A facilitates angiogenesis and alleviates inflammation in diabetic wound healing. Life sciences 5 39454994
2024 Type-H endothelial cell protein Clec14a orchestrates osteoblast activity during trabecular bone formation and patterning. Communications biology 4 39394430
2022 CLEC14A was up-regulated in hepatocellular carcinoma and may function as a potential diagnostic biomarker. Clinics (Sao Paulo, Brazil) 2 35576868
2026 Alpha-difluoromethylornithine suppresses angiogenesis via the FLI1-CLEC14A-VEGFC pathway in retinal endothelial cells. Biochemical and biophysical research communications 0 41548484