Affinage

SPECC1L

Cytospin-A · UniProt Q69YQ0

Length
1117 aa
Mass
124.5 kDa
Annotated
2026-06-10
32 papers in source corpus 12 papers cited in narrative 12 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 7/7 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

SPECC1L is a cytoskeletal scaffolding protein that coordinates actin and microtubule networks to drive the tissue movement and fusion events of craniofacial morphogenesis, particularly cranial neural crest cell (CNCC) delamination and palatogenesis (PMID:21703590, PMID:26787558, PMID:34302166). It colocalizes with both microtubules and filamentous actin, using a second coiled-coil domain (CCD2) for microtubule association and intracellular trafficking; CCD2 deletion produces a gain-of-function state with excess actin and non-muscle myosin II bundles displaced to the cell periphery, disrupting actomyosin organization and producing exencephaly, cleft palate, and omphalocele in mice (PMID:34302166). SPECC1L directly binds MYPT1 and forms a stable complex with the myosin phosphatase holoenzyme MYPT1/PP1β, distributing this phosphatase between microtubule and actin networks (PMID:36634848). Functionally, SPECC1L restrains adherens junction stability—its loss increases β-catenin and E-cadherin junctional signal and impairs CNCC delamination—acting through PI3K-AKT signaling, since PI3K-AKT activation rescues both the junctional defects and the impaired collective movement of mutant palatal mesenchyme cells (PMID:26787558, PMID:33446878). In CNCCs, SPECC1L additionally limits F-actin levels to control primary cilium length and thereby Hedgehog signaling, without itself localizing to cilia (PMID:41657552, PMID:41278885). SPECC1L is also required for bipolar spindle assembly and chromosome alignment during oocyte meiotic maturation (PMID:37698179). Genetically, SPECC1L lies downstream of IRF6 in palatogenesis, and disease-associated mutations cluster in CCD2 and the calponin homology domains, acting through a gain-of-function mechanism to perturb actin organization (PMID:31943082, PMID:37345651).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2011 Medium

    Established SPECC1L as a dual cytoskeletal-associated protein whose loss disrupts actin reorganization, adhesion, and migration, framing it as a candidate regulator of cell movement.

    Evidence Immunofluorescence colocalization with tubulin and actin, siRNA knockdown adhesion/migration assays in mammalian cells, Drosophila knockdown phenocopying integrin pathway mutants

    PMID:21703590

    Open questions at the time
    • No molecular partners identified
    • Mechanism linking SPECC1L to integrin signaling unresolved
    • No structure-function mapping of domains
  2. 2016 High

    Placed SPECC1L mechanistically upstream of adherens junction stability and PI3K-AKT signaling, explaining the CNCC delamination defect underlying craniofacial disease.

    Evidence siRNA knockdown with immunostaining/EM, mouse gene-trap knockout with CNCC lineage analysis, reciprocal pharmacological PI3K-AKT inhibition and activation rescue

    PMID:26787558

    Open questions at the time
    • Direct molecular link between SPECC1L and PI3K-AKT components not defined
    • Whether AJ effect is via cytoskeleton or signaling not separated
  3. 2020 Medium

    Defined where disease mutations cluster (CCD2 and calponin homology domains) and their effect on microtubule association, and positioned SPECC1L downstream of IRF6 in palatogenesis.

    Evidence Mouse truncation alleles, palatal shelf immunostaining, Irf6 mutant analysis, nsCL/P patient cohort sequencing

    PMID:31943082

    Open questions at the time
    • How IRF6 regulates SPECC1L expression unknown
    • Functional consequence of lost microtubule association not yet tied to phenotype
  4. 2021 High

    Resolved CCD2 as the microtubule-trafficking determinant and showed its deletion is a gain-of-function that displaces actomyosin bundles, mechanistically connecting domain loss to actin/NMII dysregulation and tissue fusion failure.

    Evidence Mouse in-frame Specc1lΔCCD2 alleles, immunofluorescence colocalization, NMII staining, embryo phenotyping

    PMID:34302166

    Open questions at the time
    • Molecular basis of the gain-of-function actin effect not defined
    • Cargo trafficked along microtubules not identified at this stage
  5. 2021 Medium

    Connected the cellular adhesion/migration defect to PI3K-AKT by showing pathway activation rescues collective movement of primary mutant mesenchyme cells.

    Evidence Live-imaging wound-repair assays of primary MEPM cells from Specc1l mutants with pharmacological PI3K-AKT activation rescue

    PMID:33446878

    Open questions at the time
    • Direct biochemical link between SPECC1L and PI3K-AKT still missing
    • How cytoskeletal scaffolding feeds into directional guidance unclear
  6. 2023 High

    Identified the first direct molecular partner, MYPT1/PP1β myosin phosphatase, and proposed SPECC1L as a scaffold that traffics the phosphatase between microtubule and actin networks—providing a biochemical mechanism for actomyosin regulation.

    Evidence Co-immunoprecipitation, BioID proximity biotinylation, direct binding assay, SPECC1L/MYPT1 interactome comparison

    PMID:36634848

    Open questions at the time
    • Whether phosphatase redistribution drives the craniofacial phenotype not tested in vivo
    • Substrates of the redistributed phosphatase not enumerated
  7. 2023 Medium

    Extended SPECC1L function to meiotic spindle assembly, indicating its cytoskeletal scaffolding role operates beyond craniofacial tissues.

    Evidence siRNA knockdown in mouse oocytes, immunofluorescence localization, live-imaging of spindle assembly and polar body extrusion

    PMID:37698179

    Open questions at the time
    • Molecular mechanism in spindle assembly unknown
    • Whether MYPT1/PP1β complex participates in oocyte phenotype untested
  8. 2025 Medium

    Linked SPECC1L to primary cilium length and Hedgehog signaling in CNCCs via F-actin control, establishing a causal F-actin–cilia axis and a genetic interaction with the IFT-A component THM1.

    Evidence Wnt1-Cre2 conditional knockout with GLI1 immunostaining and cilia measurements; F-actin depolymerization rescue and Specc1l×Thm1 compound heterozygote analysis (one preprint)

    PMID:41278885 PMID:41657552

    Open questions at the time
    • How F-actin level controls ciliogenesis mechanistically not defined
    • THM1 interaction is genetic, not biochemical
  9. 2025 Medium

    Tested the conserved Drosophila ortholog Spdi, supporting NMII/actin association and a gain-of-function effect of disease-analogous mutations on focal adhesion dynamics.

    Evidence RNAi depletion in Drosophila cells, NMII/actin colocalization, focal adhesion dynamics assays, site-directed mutagenesis (preprint)

    PMID:40236004

    Open questions at the time
    • Ortholog did not colocalize with microtubules, leaving cross-species mechanism partly divergent
    • Preprint, not peer-reviewed
  10. 2025 Low

    Indicated the N-terminal disordered region is needed for correct translation initiation, since an exon 3 deletion forces alternative start codon usage and protein truncation.

    Evidence Functional overexpression assay of a deletion construct, protein truncation analysis, Sanger sequencing

    PMID:41120295

    Open questions at the time
    • Single overexpression assay with no cellular or in vivo rescue
    • Functional consequence of the truncated protein not characterized

Open questions

Synthesis pass · forward-looking unresolved questions
  • How SPECC1L mechanistically couples its cytoskeletal scaffolding and MYPT1/PP1β trafficking to PI3K-AKT signaling, adherens junction control, and F-actin/cilia regulation within a single unified pathway remains unresolved.
  • No direct biochemical link between SPECC1L and PI3K-AKT identified
  • Whether the MYPT1/PP1β complex mediates the AJ, cilia, and spindle phenotypes untested
  • Structural basis of CCD2/CH-domain cytoskeletal binding undefined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0008092 cytoskeletal protein binding 4 GO:0060090 molecular adaptor activity 2
Localization
GO:0005856 cytoskeleton 3 GO:0005829 cytosol 2
Pathway
R-HSA-1266738 Developmental Biology 4 R-HSA-162582 Signal Transduction 3
Partners
MYPT1PPP1CB
Complex memberships
MYPT1/PP1β myosin phosphatase holoenzyme

Evidence

Reading pass · 12 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2011 SPECC1L colocalizes with both tubulin and actin in mammalian cells, and its deficiency results in defective actin-cytoskeleton reorganization, as well as abnormal cell adhesion and migration. Knockdown in Drosophila phenocopies mutants in the integrin signaling pathway. Immunofluorescence colocalization, siRNA knockdown in mammalian cells (cell adhesion/migration assays), Drosophila morpholino knockdown American journal of human genetics Medium 21703590
2016 SPECC1L knockdown in cultured cells increases staining and apico-basal diffusion of canonical adherens junction (AJ) components β-catenin and E-cadherin. In Specc1l-deficient mouse embryos, AJ stability is increased, impairing cranial neural crest cell (CNCC) delamination. PI3K-AKT signaling is reduced in mutants; moderate PI3K-AKT inhibition in wildtype cells reproduces AJ alterations; and activating PI3K-AKT rescues AJ changes caused by SPECC1L knockdown, placing SPECC1L as a novel modulator of PI3K-AKT signaling and AJ biology. siRNA knockdown in cultured cells (immunostaining, electron microscopy), mouse gene-trap knockout (immunostaining, CNCC lineage analysis), pharmacological PI3K-AKT inhibition/activation rescue experiments Scientific reports High 26787558
2020 SPECC1L mutations cluster in the second coiled-coil (CCD2) and calponin homology domains and severely affect the ability of SPECC1L to associate with microtubules. SPECC1L expression is drastically reduced in Irf6 mutant palatal shelves, placing SPECC1L downstream of IRF6 in palatogenesis. SPECC1L deficiency causes periderm layer abnormalities including ectopic apical expression of adherens junction markers. Mouse Specc1l truncation alleles (compound heterozygotes), immunostaining of palatal shelves, Irf6 mutant mouse analysis, sequencing of nsCL/P patient cohorts Human molecular genetics Medium 31943082
2021 Wild-type SPECC1L distributes evenly throughout the cytoplasm and colocalizes with both microtubules and filamentous actin. Mutant SPECC1L lacking CCD2 (SPECC1L-ΔCCD2) shows abnormal perinuclear accumulation with diminished microtubule overlap, demonstrating SPECC1L uses microtubule association for intracellular trafficking. CCD2 deletion results in gain-of-function: increased actin and non-muscle myosin II bundles displaced to the cell periphery, disrupting actomyosin organization and tissue fusion dynamics (exencephaly, cleft palate, omphalocele in homozygous mice). Mouse in-frame deletion alleles (Specc1lΔCCD2), immunofluorescence colocalization of SPECC1L with microtubules and F-actin, non-muscle myosin II staining, mouse embryo phenotypic analysis Human molecular genetics High 34302166
2021 SPECC1L-deficient primary mouse embryonic palatal mesenchyme (MEPM) cells show reduced cell speed and defective coordinated (collective) cell movement in wound-repair assays. Activation of the PI3K-AKT pathway rescues both cell speed and directional guidance defects in Specc1l mutant MEPM cells, confirming SPECC1L modulates collective mesenchymal cell movement through PI3K-AKT signaling. Live-imaging wound-repair assays of primary MEPM cells from Specc1l mutant mice, pharmacological PI3K-AKT activation rescue Scientific reports Medium 33446878
2023 SPECC1L directly binds MYPT1 and forms a stable complex with the myosin phosphatase holoenzyme MYPT1/PP1β. SPECC1L can regulate the balance of MYPT1/PP1β distribution between microtubule and filamentous actin networks, suggesting it acts as a scaffold that traffics this phosphatase between cytoskeletal substrates. Co-immunoprecipitation, proximity biotinylation (BioID), direct binding assay, interactome comparison of SPECC1L and MYPT1 The Journal of biological chemistry High 36634848
2023 SPECC1L associates with microtubules, filamentous actin, non-muscle myosin II (NMII), and membrane-associated components of adherens junctions, functioning as a cytoskeletal scaffolding protein. Syndromic SPECC1L mutations act through a gain-of-function mechanism to affect intra- and supra-cellular actin organization. Review/synthesis of multiple experimental findings (colocalization, co-IP, mouse models) Biochemical Society transactions Medium 37345651
2023 SPECC1L is required for proper bipolar spindle assembly during mouse oocyte meiotic maturation. Specc1l knockdown in oocytes caused abnormal spindle morphology, misaligned chromosomes, decreased polar body extrusion, and reduced blastocyst formation. SPECC1L localizes to cytoplasm and germinal vesicle but not to the nucleolus-like body or chromatin. siRNA knockdown in mouse oocytes, immunofluorescence localization, live-imaging of spindle assembly and polar body extrusion Reproduction (Cambridge, England) Medium 37698179
2025 Loss of SPECC1L specifically in cranial neural crest cells (Wnt1-Cre2 conditional KO) causes shortened primary cilia and increased Hedgehog (Hh) signaling (elevated GLI1) in cranial mesenchyme from E9.5, resulting in frontonasal dysplasia features. SPECC1L itself does not localize to cilia but regulates cilia length indirectly through F-actin regulation. Conditional Specc1l knockout (Wnt1-Cre2 × Specc1l-flox), GLI1 immunostaining, primary cilia length measurement, embryo phenotypic analysis Frontiers in physiology Medium 41657552
2025 SPECC1L loss leads to increased F-actin levels and shortened primary cilia. Depolymerizing F-actin in Specc1l mutant cells restored cilia length, establishing a causal inverse relationship between SPECC1L-regulated F-actin and cilia length. A genetic interaction between Specc1l and Thm1 (IFT-A component) was identified: compound/double heterozygotes show higher penetrance of cleft palate than Specc1l heterozygotes alone. F-actin depolymerization rescue of cilia length in Specc1l mutant cells, genetic compound heterozygote analysis (Specc1l × Thm1), cilia length measurement bioRxivpreprint Medium 41278885
2025 The Drosophila SPECC1L homolog Split Discs (Spdi) co-localizes with non-muscle myosin II and actin (not microtubules as proposed for the mammalian protein). RNAi depletion of Spdi increases focal adhesion dynamics. Conserved point mutations analogous to human disease variants cause a further increase in focal adhesion dynamics beyond knockdown alone, suggesting disease mutations affect cell-matrix adhesion through NMII association. RNAi depletion in Drosophila cells, immunofluorescence colocalization with NMII/actin, focal adhesion dynamics assays, site-directed mutagenesis of disease-analogous residues bioRxivpreprint Medium 40236004
2025 An intragenic SPECC1L deletion encompassing exon 3 (containing the canonical start codon) leads to alternative start codon usage and protein truncation, demonstrating the N-terminal disordered region is required for normal SPECC1L translation initiation and function in craniofacial development. Functional overexpression assay of deletion construct, protein truncation analysis, Sanger sequencing NPJ genomic medicine Low 41120295

Source papers

Stage 0 corpus · 32 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2011 Deficiency of the cytoskeletal protein SPECC1L leads to oblique facial clefting. American journal of human genetics 77 21703590
2016 SPECC1L deficiency results in increased adherens junction stability and reduced cranial neural crest cell delamination. Scientific reports 44 26787558
2014 Mutations in SPECC1L, encoding sperm antigen with calponin homology and coiled-coil domains 1-like, are found in some cases of autosomal dominant Opitz G/BBB syndrome. Journal of medical genetics 39 25412741
2015 Expanding the SPECC1L mutation phenotypic spectrum to include Teebi hypertelorism syndrome. American journal of medical genetics. Part A 32 26111080
2018 Phenotypic spectrum associated with SPECC1L pathogenic variants: new families and critical review of the nosology of Teebi, Opitz GBBB, and Baraitser-Winter syndromes. European journal of medical genetics 30 30472488
2020 SPECC1L regulates palate development downstream of IRF6. Human molecular genetics 24 31943082
2014 Functional analysis of SPECC1L in craniofacial development and oblique facial cleft pathogenesis. Plastic and reconstructive surgery 22 25357034
2021 In-frame deletion of SPECC1L microtubule association domain results in gain-of-function phenotypes affecting embryonic tissue movement and fusion events. Human molecular genetics 15 34302166
2023 SPECC1L: a cytoskeletal protein that regulates embryonic tissue dynamics. Biochemical Society transactions 12 37345651
2021 SPECC1L-deficient primary mouse embryonic palatal mesenchyme cells show speed and directionality defects. Scientific reports 12 33446878
2023 SPECC1L binds the myosin phosphatase complex MYPT1/PP1β and can regulate its distribution between microtubules and filamentous actin. The Journal of biological chemistry 11 36634848
2020 A novel SPECC1L mutation causing Teebi hypertelorism syndrome: Expanding phenotypic and genetic spectrum. European journal of medical genetics 10 31953237
2020 Congenital diaphragmatic hernia as a prominent feature of a SPECC1L-related syndrome. American journal of medical genetics. Part A 8 32954677
2020 Recurrent SPECC1L-NTRK fusions in pediatric sarcoma and brain tumors. Cold Spring Harbor molecular case studies 7 33144287
2022 BCL6-SPECC1L: A Novel Fusion Gene in Nasopharyngeal Carcinoma. Technology in cancer research & treatment 5 36412101
2024 Changes in expression of VGF, SPECC1L, HLA-DRA and RANBP3L act with APOE E4 to alter risk for late onset Alzheimer's disease. Scientific reports 3 38942763
2021 A novel p.Pro871Leu missense mutation in SPECC1L gene causing craniosynostosis in a patient. Orthodontics & craniofacial research 3 33527670
2025 First Report of SPECC1L::ALK Fusion in Medullary Thyroid Carcinoma with Remarkable Response to Alectinib. Thyroid : official journal of the American Thyroid Association 2 40376737
2025 Oral Undifferentiated Pleomorphic Sarcoma: A Novel SPECC1L::TERT Gene Fusion and a Comprehensive Literature Review. Genes 2 40725486
2025 Genetic interaction of Specc1l and Thm1 reveals cytoskeletal-ciliary crosstalk. bioRxiv : the preprint server for biology 2 41278885
2024 NTRK-rearranged spindle cell tumor with SPECC1L-NTRK3 fusion in the thoracic spine: a case report. Journal of cancer research and clinical oncology 2 39661164
2023 Specc1l deficiency leads to abnormal oocyte meiosis and reduced blastocyst development in mouse. Reproduction (Cambridge, England) 2 37698179
2022 SPECC1L Mutations Are Not Common in Sporadic Cases of Opitz G/BBB Syndrome. Genes 2 35205294
2025 Disruption of SPECC1L translation initiation by intragenic deletion: novel pathogenic mechanism in Teebi-hypertelorism syndrome. NPJ genomic medicine 1 41120295
2023 Efficacy and safety of iruplinalkib (WX‑0593) on non‑small cell lung cancer with SPECC1L‑ALK fusion: A case report. Experimental and therapeutic medicine 1 38234623
2026 Loss of SPECC1L in cranial neural crest cells results in increased hedgehog signaling and frontonasal dysplasia. Frontiers in physiology 0 41657552
2025 The Drosophila SPECC1L homolog, Split Discs, co-localizes with non-muscle myosin II and regulates focal adhesion dynamics. bioRxiv : the preprint server for biology 0 40236004
2025 Case Report: Dual resistance to dasatinib/olverembatinib in accelerated-phase cml: identification of a novel SPECC1L-inserted e8a2 BCR::ABL1 transcript and ABL1 V379I mutation. Frontiers in oncology 0 41211450
2025 Loss of SPECC1L in cranial neural crest cells results in increased hedgehog signaling and frontonasal dysplasia. bioRxiv : the preprint server for biology 0 41332626
2024 Clinical and Molecular Traits of a Novel SPECC1L-ALK Fusion in a Patient with Advanced Non-Small Cell Lung Cancer. Journal of personalized medicine 0 39063924
2023 [Identification of a child with Teebi hypertelorism syndrome 1 due to variant of SPECC1L gene]. Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics 0 37532501
2023 The Human Brainome: changes in expression of VGF, SPECC1L, HLA-DRA and RANBP3L act with APOE E4 to alter risk for late onset Alzheimer's disease. Research square 0 38168398

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