KIAA1217/SKT and its paralog p140Cap are centrosomal proteins that regulate ciliogenesis through Src family signaling pathway

ABSTRACT Centrosomes organize the microtubule network along the cell cycle and drive cilia assembly in resting cells to allow sensory or motility functions. Defects in cilia formation underlie ciliopathies and skeletal disorders, but the molecular regulators that couple centrosomes to signaling and cytoskeletal networks remain incompletely defined. Through BioID screening for CYLD interactors, we identify KIAA1217/SKT as a centrosomal and microtubule plus-end protein that also associates with focal adhesions. KIAA1217 loss in RPE-1 cells impaired ciliogenesis, producing fewer and shorter cilia. Domain mapping revealed an N-terminal centrosomal targeting domain and an EB1-dependent targeting of KIAA1217 to microtubule tips via C-terminal SxIP motifs. Importantly, defects caused by loss of KIAA1217 or its paralog p140Cap were rescued by inhibiting actin polymerization or Src activity, indicating regulation of actin polymerization through Src family activity. Together, our findings establish KIAA1217 as a positive regulator of ciliogenesis that integrates Src-dependent signaling, centrosomal architecture, and actin remodeling and may open new research avenues to understand KIAA1217-associated pathologies as vertebrate malformation and epithelia-mesenchymal transition. Centrosome, Ciliogenesis, Actin, Src family signaling, KIAA217/SKT, p140Cap Competing Interest Statement The authors have declared no competing interest. Footnotes The title has been changed to reflect our findings. Abbreviations - BB - basal body - FA - focal adhesion - ECM - extracellular matrix - EMT - epithelio-mesenchymal transition - BioID - In vivo biotinylation identification - MS - mass spectrometry - SKT - sickle tail - GFP - green fluorescent protein - aPKC - atypical protein kinase C - MIM - Missing-in-Metastasis - PKD - polycystic kidney diseases - ARPKD - autosomal recessive polycystic kidney diseases - ADPKD - autosomal dominant polycystic kidney diseases - ILK - integrin-linked-kinase - EGF - epidermal growth factor - SU - SU6656 - CD - CytochalasinD - IF - immunofluorescence - WB - Western blot - U-ExM - ultrastructural expansion microscopy - ATP - adenosin triphosphate - KO - knock-out - IVD - intervertebral disc - NP - nucleus pulposus - AF - annulus fibrosus - EP - endplate - MMP - matrix metalloproteinase