Phospho-regulation of KIBRA by CDK1 and CDC14 phosphatase controls cell-cycle progression

Abstract

KIBRA (kidney- and brain-expressed protein) is a novel regulator of the Hippo pathway, which controls tissue growth and tumorigenesis by regulating both cell proliferation and apoptosis. In mammals, KIBRA is associated with memory performance. The physiological function and regulation of KIBRA in non-neuronal cells remain largely unclear. We reported recently that KIBRA is phosphorylated by the mitotic kinases Aurora-A and -B. In the present study, we have expanded our analysis of KIBRA's role in cell-cycle progression. We show that KIBRA is also phosphorylated by CDK1 (cyclin-dependent kinase 1) in response to spindle damage stress. We have identified KIBRA Ser(542) and Ser(931) as main phosphorylation sites for CDK1 both in vitro and in vivo. Moreover, we found that the CDC (cell division cycle) 14A/B phosphatases associate with KIBRA, and CDK1-non-phosphorylatable KIBRA has greatly reduced interaction with CDC14B. CDC14A/B dephosphorylate CDK1-phosphorylated KIBRA in vitro and in cells. By using inducible-expression cell lines, we show further that phospho-regulation of KIBRA by CDK1 and CDC14 is involved in mitotic exit under spindle stress. Our results reveal a new mechanism through which KIBRA regulates cell-cycle progression.

Human phosphatase CDC14A is recruited to the cell leading edge to regulate cell migration and adhesion

“…The protein KIBRA is an upstream regulator of Hippo pathway that is critical for the control of contact inhibition and organ size (40). KIBRA was previously reported to be a hCDC14A substrate that also has functions in cell migration (39). We now show that KIBRA colocalizes with hCDC14A at the leading edge and that transient expression of KIBRA bypassed the hCDC14A PD cell migration defects.…”

“…S7 C and D). A slight downshift in the migration of the KIBRA band on SDS/PAGE was observed in the immunoblot, indicating the dephosphorylation of KIBRA by hCDC14A (39) (Fig. 4G).…”

“…The WW domain protein KIBRA has been described as hCDC14A substrate (39). This upstream regulator of Hippo pathway (40)(41)(42) controls the activity of the transcriptional coactivator YAP through its interaction with large-tumor suppressor kinase 1 (LATS1) and LATS2 kinases (42).…”

Oncoprotein YAP Regulates the Spindle Checkpoint Activation in a Mitotic Phosphorylation-dependent Manner through Up-regulation of BubR1

“…The Slidebook 4.2 software (Intelligent Imaging Innovations, Denver, CO) was used for analyzing and processing all immunofluorescence images. Mitotic index assessment and flow cytometry were performed as we have described (29).…”

Human phosphatase CDC14A regulates actin organization through dephosphorylation of epithelial protein lost in neoplasm

“…The only known substrate of hCDC14A that acts within the actin cytoskeleton is the protein Kibra (20,21). However, considering the broad distribution of hCDC14A throughout the actin network, it is highly likely that hCDC14A dephosphorylates additional actin-associated proteins.…”