CK1‐mediated phosphorylation of FAM110A promotes its interaction with mitotic spindle and controls chromosomal alignment

Abstract

Progression through the cell cycle is driven by cyclin-dependent kinases that control gene expression, orchestration of mitotic spindle, and cell division. To identify new regulators of the cell cycle, we performed transcriptomic analysis of human nontransformed cells expressing a fluorescent ubiquitination-based cell cycle indicator and identified 701 transcripts differentially expressed in G1 and G2 cells. Family with sequence similarity 110 member A (FAM110A) protein is highly expressed in G2 cells and localized at mitotic spindle and spindle poles during mitosis. Depletion of FAM110A impairs chromosomal alignment, delays metaphase-to-anaphase transition, and affects spindle positioning. Using mass spectrometry and immunoprecipitation, we identified casein kinase I (CK1) in complex with FAM110A during mitosis. CK1 phosphorylates the C-terminal domain of FAM110A in vitro, and inhibition of CK1 reduces phosphorylation of mitotic FAM110A. Wild-type FAM110A, but not the FAM110A-S252-S255A mutant deficient in CK1 phosphorylation, rescues the chromosomal alignment, duration of mitosis, and orientation of the mitotic spindle after depletion of endogenous FAM110A. We propose that CK1 regulates chromosomal alignment by phosphorylating FAM110A and promoting its interaction with mitotic spindle.

FAM110A promotes mitotic spindle formation by linking microtubules with actin cytoskeleton

“…1 B ). Interestingly, AlphaFold2 showed that interaction of tubulin could potentially be mediated by a conserved alpha-helix comprising residues 188–221 of FAM110A that are close to the previously reported phosphorylated sites promoting the binding of FAM110A to the spindle poles ( 20 ) ( Fig. 1 C ).…”

“…In our previous work, we showed that FAM110A interacts with tubulin and actin during mitosis ( 20 ). Here, we aimed to map and functionally characterize the interaction of FAM110A with both cytoskeletal systems.…”

“…We have recently shown that FAM110A localizes to the spindle poles and that its depletion delays progression through mitosis ( 20 ). In addition, mitotic function of FAM110A was dependent on its phosphorylation by CK1 that promoted its localization to the spindle poles in metaphase ( 20 ).…”

“…We have recently shown that FAM110A localizes to the spindle poles and that its depletion delays progression through mitosis ( 20 ). In addition, mitotic function of FAM110A was dependent on its phosphorylation by CK1 that promoted its localization to the spindle poles in metaphase ( 20 ). Here, we report that mitotic function of FAM110A depends on its ability to bind actin and microtubules through its N- and C-terminal domains, respectively.…”

CK1 Is a Druggable Regulator of Microtubule Dynamics and Microtubule-Associated Processes

“…In this study, it was demonstrated that CK1 interacts with FAM110A during mitosis, and inhibition of CK1 or depletion of FAM110A, led to chromosomal alignment defects and delayed mitosis progression ( Figure 3 ). Interestingly, defects in chromosomal alignment were rescued by mimicking phosphorylation with FAM110A-S252-255E mutants [ 68 ]. Functional binding partners of CK1, such as the anchoring proteins FAM83 and FAM110A, could be used as alternative targets in cancer treatment by blocking specifically the interaction of CK1 isoforms with these anchoring proteins and thus, inhibiting CK1 isoform-mediated substrate phosphorylation (see also Section 7.4 ) [ 68 ].…”