CDK10/cyclin M is a protein kinase that controls ETS2 degradation and is deficient in STAR syndrome

Abstract

Cyclin-dependent kinases (CDKs) regulate a variety of fundamental cellular processes. CDK10 stands out as one of the last orphan CDKs for which no activating cyclin has been identified and no kinase activity revealed. Previous work has shown that CDK10 silencing increases ETS2 (v-ets erythroblastosis virus E26 oncogene homolog 2)-driven activation of the MAPK pathway, which confers tamoxifen resistance to breast cancer cells. The precise mechanisms by which CDK10 modulates ETS2 activity, and more generally the functions of CDK10, remain elusive. Here we demonstrate that CDK10 is a cyclin-dependent kinase by identifying cyclin M as an activating cyclin. Cyclin M, an orphan cyclin, is the product of FAM58A, whose mutations cause STAR syndrome, a human developmental anomaly whose features include toe syndactyly, telecanthus, and anogenital and renal malformations. We show that STAR syndrome-associated cyclin M mutants are unable to interact with CDK10. Cyclin M silencing phenocopies CDK10 silencing in increasing c-Raf and in conferring tamoxifen resistance to breast cancer cells. CDK10/cyclin M phosphorylates ETS2 in vitro, and in cells it positively controls ETS2 degradation by the proteasome. ETS2 protein levels are increased in cells derived from a STAR patient, and this increase is attributable to decreased cyclin M levels. Altogether, our results reveal an additional regulatory mechanism for ETS2, which plays key roles in cancer and development. They also shed light on the molecular mechanisms underlying STAR syndrome.C yclin-dependent kinases (CDKs) play a pivotal role in the control of a number of fundamental cellular processes (1). The human genome contains 21 genes encoding proteins that can be considered as members of the CDK family owing to their sequence similarity with bona fide CDKs, those known to be activated by cyclins (2). Although discovered almost 20 y ago (3, 4), CDK10 remains one of the two CDKs without an identified cyclin partner. This knowledge gap has largely impeded the exploration of its biological functions. CDK10 can act as a positive cell cycle regulator in some cells (5, 6) or as a tumor suppressor in others (7,8). CDK10 interacts with the ETS2 (v-ets erythroblastosis virus E26 oncogene homolog 2) transcription factor and inhibits its transcriptional activity through an unknown mechanism (9). CDK10 knockdown derepresses ETS2, which increases the expression of the c-Raf protein kinase, activates the MAPK pathway, and induces resistance of MCF7 cells to tamoxifen (6).Here, we deorphanize CDK10 by identifying cyclin M, the product of FAM58A, as a binding partner. Mutations in this gene that predict absence or truncation of cyclin M are associated with STAR syndrome, whose features include toe syndactyly, telecanthus, and anogenital and renal malformations in heterozygous females (10). However, both the functions of cyclin M and the pathogenesis of STAR syndrome remain unknown. We show that a recombinant CDK10/cyclin M heterodimer is an active protein kinase that phosphorylates ETS2 in v...

STAR syndrome-associated CDK10/Cyclin M regulates actin network architecture and ciliogenesis

“…The recent discovery of Cyclin M as a CDK10 binding partner has enabled exploration of this novel protein kinase's function and downstream targets. 27 Here, we discover that CDK10/CycM is a negative regulator of ciliogenesis, by showing that knockdown of this kinase increases the percentage of ciliated cells and also cilia length. This effect was not attributable to a perturbation in cell cycle phasing, which is controlled by various CDKs.…”

“…26 We recently reported that Cyclin M (CycM), encoded by FAM58A, interacts with Cyclin-Dependent Kinase 10 (CDK10) to form an active protein kinase. 27 We demonstrated that STAR syndrome-associated CycM mutants fail to interact with CDK10, thus compromising CDK10 kinase activity. Young girls affected by STAR syndrome suffer from general growth retardation.…”

Targeting Wnts at the Source—New Mechanisms, New Biomarkers, New Drugs

“…In addition to head and neck squamous cell carcinomas, FAT1 mutations are frequently observed in central nervous system, colorectal, and ovarian cancers. FAM58A (family with sequence similarity 58, member A) encodes cyclin M, which regulates CDK10 and interacts with SALL1 (62,63). Mutations in FAM58A cause an X-linked dominant disorder characterized by syndactyly, telecanthus, anogenital, and renal malformations.…”

CDK10 Mutations in Humans and Mice Cause Severe Growth Retardation, Spine Malformations, and Developmental Delays

“…The levels of ETS2 were substantially higher in CDK10 mutant cells than in control cells, which is in accordance with the finding that ETS2 is a substrate of the CDK10/cyclin M complex. 7 Finally, expression levels of genes involved in ciliogenesis, including BBS4 (MIM: 600374), CEP290 (MIM: 610142), and RPGRIP1L (MIM: 610937) ( Figure S7D), differed between organs with mutant CDK10 and control organs. Mutations in these genes can lead to ciliopathies such as Bardet-Biedl syndrome (MIM: 615982) or Joubert syndrome (type 5 [MIM: 610188] or type 7 [MIM: 611560]).…”

“…CDK10 is activated by cyclin M and interacts with ETS2. 6,7 To confirm the increase in ETS2 at the protein level, we performed western blots with lysates of subject-derived primary fibroblasts (see Figure 2D). The levels of ETS2 were substantially higher in CDK10 mutant cells than in control cells, which is in accordance with the finding that ETS2 is a substrate of the CDK10/cyclin M complex.…”