Affinage

TESK1

Dual specificity testis-specific protein kinase 1 · UniProt Q15569

Length
626 aa
Mass
67.7 kDa
Annotated
2026-04-28
15 papers in source corpus 9 papers cited in narrative 9 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

TESK1 is a serine/threonine kinase that phosphorylates cofilin on its conserved inhibitory serine residue to stabilize F-actin stress fibers and regulate cell spreading, focal adhesion dynamics, and adherens junction integrity (PMID:8537404, PMID:30115939, PMID:17118962). Its kinase activity toward cofilin is negatively regulated by the focal adhesion adaptor actopaxin (which dissociates from TESK1 upon fibronectin adhesion to permit cofilin phosphorylation and cell spreading) and by Spred1 (which inhibits TESK1 to keep actin fibers dynamic), while TESK1 itself inhibits MARKK/TAO1 to prevent microtubule disruption, forming a regulatory triangle linking actin and microtubule cytoskeleton control (PMID:15817463, PMID:18216281). Independent of its kinase activity, TESK1 sequesters Sprouty proteins to cytoplasmic vesicles, disrupting Sprouty–Grb2 interaction and thereby modulating RTK-Ras-ERK signaling during processes such as neurite outgrowth (PMID:17974561, PMID:12027893). In Drosophila, the TESK1 ortholog Cdi acts downstream of Rac1 and upstream of cofilin/Slingshot to control actin organization during spermatogenesis and epithelial morphogenesis (PMID:15169836, PMID:17118962).

Mechanistic history

Synthesis pass · year-by-year structured walk · 9 steps
  1. 1995 High

    Identification of TESK1 as a novel serine/threonine kinase established the existence of a kinase with an unusual domain architecture — an N-terminal kinase domain and a C-terminal proline-rich region — whose biological substrates remained unknown.

    Evidence cDNA cloning from human testis and in vitro kinase assay using myelin basic protein as substrate in COS cells

    PMID:8537404

    Open questions at the time
    • Physiological substrate not identified
    • Cellular function unknown
    • Regulation of kinase activity not explored
  2. 2001 Medium

    Demonstration that TESK1 phosphorylates cofilin and is highly expressed in testicular germ cells connected this kinase to actin cytoskeletal regulation and suggested a tissue-specific role in spermatogenesis.

    Evidence Biochemical phosphorylation assay and transgenic lacZ reporter for TESK1 promoter activity

    PMID:11511097

    Open questions at the time
    • Specific serine residue on cofilin not confirmed in this study
    • Functional consequence of cofilin phosphorylation by TESK1 not directly tested in cells
  3. 2002 Medium

    Discovery that TESK1 interacts with Sprouty4 and relocalizes it to cytoplasmic vesicles in a growth-factor-stimulated manner revealed a kinase-independent scaffolding function linking TESK1 to RTK signaling.

    Evidence Yeast two-hybrid screen, reciprocal coimmunoprecipitation, and colocalization microscopy in mammalian cells

    PMID:12027893

    Open questions at the time
    • Functional consequence for Ras-ERK signaling not tested
    • Whether kinase activity is required for Sprouty sequestration not determined
  4. 2004 Medium

    Genetic epistasis in Drosophila placed the TESK1 ortholog Cdi downstream of Rac1 and upstream of cofilin, establishing an in vivo signaling hierarchy for this kinase in actin-dependent spermatogenesis.

    Evidence Gain-of-function screen and double mutant analysis in Drosophila (Rac1N17 suppression, cdi/Rac1 double loss-of-function fertility defects)

    PMID:15169836

    Open questions at the time
    • Direct biochemical link between Rac1 and Cdi not demonstrated
    • Mechanism of Rac1-dependent Cdi activation unclear
  5. 2005 High

    Identification of actopaxin as a direct TESK1-binding partner that inhibits TESK1 kinase activity established a mechanism coupling integrin-mediated adhesion to cofilin phosphorylation: fibronectin engagement releases actopaxin inhibition, permitting TESK1-dependent cofilin phosphorylation and cell spreading.

    Evidence Direct pulldown, in vitro kinase assay, coimmunoprecipitation, domain mapping, and cell spreading assay with phospho-cofilin readout

    PMID:15817463

    Open questions at the time
    • How fibronectin adhesion disrupts the actopaxin–TESK1 complex is unknown
    • Other focal adhesion regulators of TESK1 not explored
  6. 2006 Medium

    Demonstration that Drosophila Cdi controls adherens junction integrity and apical actin organization in epithelia via cofilin phosphorylation extended the functional scope of TESK1 beyond spermatogenesis to epithelial morphogenesis and RTK apical localization.

    Evidence Gain- and loss-of-function genetics in Drosophila eye epithelium with DE-cadherin, β-catenin, and actin localization readouts

    PMID:17118962

    Open questions at the time
    • Whether mammalian TESK1 similarly regulates adherens junctions not tested
    • Relationship between cofilin phosphorylation and junction assembly not mechanistically resolved
  7. 2007 High

    Detailed dissection of TESK1–Sprouty2 interaction revealed a kinase-independent mechanism: TESK1 sequesters Spry2 to endosomal vesicles, blocks Spry2–Grb2 binding, and prevents Spry2 dephosphorylation by PP2A, thereby nullifying Spry2 inhibition of RTK signaling and promoting bFGF-induced neurite outgrowth.

    Evidence Endogenous coimmunoprecipitation (mouse tissues and cells), kinase-dead mutant analysis, Grb2 and PP2A binding assays, siRNA knockdown with neurite outgrowth readout in PC12 cells

    PMID:17974561

    Open questions at the time
    • Whether TESK1 regulates all Sprouty family members equivalently is unclear
    • Endosomal targeting mechanism for TESK1 not defined
  8. 2008 High

    Discovery that Spred1 inhibits TESK1, and that TESK1 reciprocally inhibits MARKK/TAO1, established a three-way regulatory circuit linking actin stabilization (via cofilin phosphorylation) and microtubule dynamics (via MARKK inhibition) through a single kinase node.

    Evidence Yeast two-hybrid, coimmunoprecipitation, overexpression/inhibition in CHO cells with stress fiber formation and microtubule disruption readouts

    PMID:18216281

    Open questions at the time
    • Direct phosphorylation of MARKK/TAO1 by TESK1 not demonstrated
    • Physiological contexts where this triangle operates in vivo not identified
  9. 2018 High

    Genetic knockout of TESK1 in podocytes demonstrated that TESK1 is a functionally non-redundant cofilin kinase that compensates for ROK pathway inhibition, resolving the question of whether TESK1 and LIMK pathways are interchangeable in regulating cell motility.

    Evidence TESK1 knockout podocytes, pharmacological ROK inhibition (Y27632), phospho-cofilin western blot and motility assay

    PMID:30115939

    Open questions at the time
    • Whether TESK1 loss affects podocyte function in vivo (e.g., proteinuria) is not tested
    • Relative contributions of TESK1 vs. LIMK to cofilin phosphorylation in other cell types unclear

Open questions

Synthesis pass · forward-looking unresolved questions
  • The upstream signals that directly activate TESK1 kinase activity (beyond relief of actopaxin inhibition) remain undefined, and no structural model exists for TESK1 or its complexes with regulators.
  • No activating kinase or post-translational modification identified for TESK1
  • No crystal or cryo-EM structure available
  • In vivo phenotype of mammalian TESK1 knockout not reported beyond cultured podocytes

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140096 catalytic activity, acting on a protein 5
Localization
GO:0005829 cytosol 2 GO:0031410 cytoplasmic vesicle 2
Pathway
R-HSA-162582 Signal Transduction 2 R-HSA-1500931 Cell-Cell communication 1
Partners
CFL1PARVASPRED1SPRY2SPRY4TAOK1

Evidence

Reading pass · 9 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1995 TESK1 is a serine/threonine kinase; protein expressed in COS cells exhibited kinase activity using myelin basic protein as substrate, and the protein contains an N-terminal kinase domain followed by a C-terminal proline-rich region. In vitro kinase assay with myelin basic protein as substrate; cDNA cloning and sequence analysis The Journal of biological chemistry High 8537404
2001 TESK1 has the potential to phosphorylate cofilin and induce actin cytoskeletal reorganization, and is highly expressed in testicular germ cells. Transgenic reporter (lacZ linked to TESK1 promoter) and biochemical phosphorylation assay Biochemical and biophysical research communications Medium 11511097
2002 TESK1 interacts with human Sprouty4 (hSpry4); the interaction was confirmed by coimmunoprecipitation and the two proteins colocalize in cytoplasmic vesicles; the interaction increases upon growth factor stimulation. Yeast two-hybrid screen, coimmunoprecipitation, colocalization by microscopy European journal of biochemistry Medium 12027893
2005 TESK1 directly interacts with the focal adhesion protein actopaxin via their carboxyl termini; actopaxin binding inhibits TESK1 kinase activity in vitro; the interaction is negatively regulated by adhesion to fibronectin; loss of this interaction impairs cofilin phosphorylation upon matrix adhesion and retards cell spreading. Direct binding assay (pulldown), in vitro kinase assay, domain mapping, coimmunoprecipitation, cell spreading assay with cofilin phosphorylation readout The Journal of biological chemistry High 15817463
2007 Tesk1 binds endogenous Spry2 and relocalizes it to vesicles including endosomes, inhibiting Spry2 translocation to membrane ruffles upon growth factor stimulation; independently of its kinase activity, Tesk1 nullifies Spry2 inhibitory function by abrogating Spry2 interaction with Grb2 and by interfering with Spry2 serine dephosphorylation (impeding Spry2 binding to PP2A catalytic subunit); Tesk1 depletion reduces bFGF-induced neurite outgrowth in PC12 cells. Coimmunoprecipitation (endogenous proteins and mouse tissues), subcellular localization imaging, kinase-dead mutant analysis, Grb2 interaction assay, PP2A binding assay, siRNA knockdown with neurite outgrowth readout The Journal of biological chemistry High 17974561
2008 TESK1 binds to and inhibits the kinase MARKK/TAO1, blocking MARKK-induced microtubule disruption; Spred1 binds TESK1 and inhibits TESK1, thereby making F-actin fibers dynamic by reducing cofilin phosphorylation; TESK1 phosphorylates cofilin to stabilize F-actin stress fibers; these three proteins (Spred1, MARKK, TESK1) form a regulatory triangle linking actin and microtubule cytoskeleton dynamics. Yeast two-hybrid, coimmunoprecipitation, overexpression/inhibition in CHO cells with cytoskeletal readouts (stress fiber formation, MT disruption), cofilin phosphorylation assay Molecular biology of the cell High 18216281
2004 In Drosophila, the TESK1 ortholog Cdi (Center divider) acts downstream of Rac1 and upstream of Cofilin in a Rac1-Cdi-Cofilin pathway regulating spermatogenesis; genetic epistasis shows that Cdi expression suppresses dominant-negative Rac1 (Rac1N17) rough-eye phenotype, and Rac1 loss-of-function fertility defects are worsened by cdi loss-of-function. Genetic epistasis (gain-of-function screen, dominant-negative suppression, double mutant analysis in Drosophila) Journal of cell science Medium 15169836
2006 In Drosophila, the TESK1 ortholog Cdi controls actin organization and adherens junction integrity (DE-cadherin and beta-catenin localization) in the eye epithelium via ADF/cofilin phosphorylation; gain- and loss-of-function of cdi alter apical actin organization and Sevenless RTK apical localization; the ADF/cofilin phosphatase Slingshot (ssh) antagonizes Cdi function. Gain- and loss-of-function genetics in Drosophila, localization of actin and adherens junction markers, EP modifier screen Journal of cell science Medium 17118962
2018 TESK1 phosphorylates cofilin-1 (CFL1) on the same serine residue as LIMK in glomerular podocytes; in TESK1 knockout podocytes, ROK inhibition (Y27632) effectively reduces phospho-CFL1 levels (whereas in wild-type cells TESK1 compensates for ROK inhibition); TESK1 KO abolishes the motility-promoting effect of ROK inhibition, demonstrating TESK1 regulates podocyte cytoskeletal dynamics. TESK1 knockout cells, pharmacological ROK inhibition (Y27632), phospho-cofilin western blot, podocyte motility assay Scientific reports High 30115939

Source papers

Stage 0 corpus · 15 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2002 Human sprouty 4, a new ras antagonist on 5q31, interacts with the dual specificity kinase TESK1. European journal of biochemistry 85 12027893
1995 Identification and characterization of a novel protein kinase, TESK1, specifically expressed in testicular germ cells. The Journal of biological chemistry 70 8537404
2008 Spred1 and TESK1--two new interaction partners of the kinase MARKK/TAO1 that link the microtubule and actin cytoskeleton. Molecular biology of the cell 54 18216281
2005 Actopaxin interacts with TESK1 to regulate cell spreading on fibronectin. The Journal of biological chemistry 42 15817463
1998 Stage-specific expression of testis-specific protein kinase 1 (TESK1) in rat spermatogenic cells. Biochemical and biophysical research communications 33 9705840
2007 Tesk1 interacts with Spry2 to abrogate its inhibition of ERK phosphorylation downstream of receptor tyrosine kinase signaling. The Journal of biological chemistry 32 17974561
2004 A screen for modifiers of RacGAP(84C) gain-of-function in the Drosophila eye revealed the LIM kinase Cdi/TESK1 as a downstream effector of Rac1 during spermatogenesis. Journal of cell science 21 15169836
2014 Cloning and characterization of tesk1, a novel spermatogenesis-related gene, in the tongue sole (Cynoglossus semilaevis). PloS one 20 25271995
2001 Cell-type-specific expression of a TESK1 promoter-linked lacZ gene in transgenic mice. Biochemical and biophysical research communications 19 11511097
2018 Decreased TESK1-mediated cofilin 1 phosphorylation in the jejunum of IBS-D patients may explain increased female predisposition to epithelial dysfunction. Scientific reports 18 29396473
1999 Drosophila center divider gene is expressed in CNS midline cells and encodes a developmentally regulated protein kinase orthologous to human TESK1. DNA and cell biology 17 10390152
1998 Structural organization and chromosomal localization of the mouse tesk1 (testis-specific protein kinase 1) gene. Gene 12 9469938
2018 Regulation of cofilin phosphorylation in glomerular podocytes by testis specific kinase 1 (TESK1). Scientific reports 10 30115939
2006 The Cdi/TESK1 kinase is required for Sevenless signaling and epithelial organization in the Drosophila eye. Journal of cell science 7 17118962
2016 Expression analysis and characterization of an autosome-localized tesk1 gene in half-smooth tongue sole (Cynoglossus semilaevis). Gene 5 26869317