SCFFbxw5 targets kinesin‐13 proteins to facilitate ciliogenesis

• Published in: The EMBO journal Vol. 40; no. 18; pp. e107735 - n/a
• Main Authors: Schweiggert, Jörg, Habeck, Gregor, Hess, Sandra, Mikus, Felix, Beloshistov, Roman, Meese, Klaus, Hata, Shoji, Knobeloch, Klaus‐Peter, Melchior, Frauke
• Format: Journal Article
• Language: English
• Published: Heidelberg Blackwell Publishing Ltd 15.09.2021; John Wiley and Sons Inc
• Subjects: Adenomatous polyposis coli; Basal bodies; Cdc34 protein; Cell cycle; cilia; Cullin‐RING ligase; Degradation; Fbxw5; G2 phase; Kinesin; MCAK; Proteasomes; Protein arrays; Proteins; Substrates; Tumorigenesis; Ubiquitin; Ubiquitin-protein ligase
• ISSN: 0261-4189; 1460-2075
• DOI: 10.15252/embj.2021107735

Microtubule depolymerases of the kinesin‐13 family play important roles in various cellular processes and are frequently overexpressed in different cancer types. Despite the importance of their correct abundance, remarkably little is known about how their levels are regulated in cells. Using comprehensive screening on protein microarrays, we identified 161 candidate substrates of the multi‐subunit ubiquitin E3 ligase SCFFbxw5, including the kinesin‐13 member Kif2c/MCAK. In vitro reconstitution assays demonstrate that MCAK and its closely related orthologs Kif2a and Kif2b become efficiently polyubiquitylated by neddylated SCFFbxw5 and Cdc34, without requiring preceding modifications. In cells, SCFFbxw5 targets MCAK for proteasomal degradation predominantly during G2. While this seems largely dispensable for mitotic progression, loss of Fbxw5 leads to increased MCAK levels at basal bodies and impairs ciliogenesis in the following G1/G0, which can be rescued by concomitant knockdown of MCAK, Kif2a or Kif2b. We thus propose a novel regulatory event of ciliogenesis that begins already within the G2 phase of the preceding cell cycle. SYNOPSIS Despite their importance in normal cellular physiology and tumorigenesis, regulation of microtubule depolymerases remains little understood. Here, the kinesin‐13 family member MCAK is found to be ubiquitylated and degraded via SCFFbxw5 to facilitate ciliogenesis. SCFFbxw5 modifies kinesin‐13 proteins with K48‐linked polyubiquitin chains. SCFFbxw5‐dependent polyubiquitylation targets MCAK for degradation during G2 phase, while post‐mitotic degradation is driven by the APC/C ligase. Defects in MCAK ubiquitylation and degradation cause its accumulation at basal bodies during the subsequent G1/G0 phase, impairing ciliogenesis. Ubiquitin‐dependent proteolysis of microtubule depolymerase MCAK restrains its post‐mitotic accumulation at basal bodies to allow ciliogenesis in G1/G0 phase.