Identification of C dk targets that control cytokinesis

Abstract

The final event of the eukaryotic cell cycle is cytokinesis, when two new daughter cells are born. How the timing and execution of cytokinesis is controlled is poorly understood. Here, we show that downregulation of cyclin-dependent kinase (Cdk) activity, together with upregulation of its counteracting phosphatase Cdc14, controls each of the sequential steps of cytokinesis, including furrow ingression, membrane resolution and cell separation in budding yeast. We use phosphoproteome analysis of mitotic exit to identify Cdk targets that are dephosphorylated at the time of cytokinesis. We then apply a new and widely applicable tool to generate conditionally phosphorylated proteins to identify those whose dephosphorylation is required for cytokinesis. This approach identifies Aip1, Ede1 and Inn1 as cytokinetic regulators. Our results suggest that cytokinesis is coordinately controlled by the master cell cycle regulator Cdk together with its counteracting phosphatase and that it is executed by concerted dephosphorylation of Cdk targets involved in several cell biological processes.

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

“…Yeast cells that lack CDC14 function fail to form an actomyosin ring, whereas it forms prematurely after overexpression of CDC14 (55). Cdc14 regulates F-actin dynamics through dephosphorylation of actin-interacting proteins such as Iqg1 and Aip1 (55,56). Consistent with these data from yeast, hCDC14A also regulates actin dynamics, however, in interphase.…”

Mechanisms regulating phosphatase specificity and the removal of individual phosphorylation sites during mitotic exit

“…This preferential dephosphorylation of lower abundance TP sites during mitotic exit has also been reported by others in mammalian cells . Interestingly, this situation is reversed in budding yeast, where SP residues are preferentially dephosphorylated by the Cdc14 phosphatase , which may explain the divergent roles of Cdc14 between organisms. In yeast, Cdc14 primarily drives mitotic exit, whereas in higher eukaryotes, the role of Cdc14 is less clear .…”

Coupling changes in cell shape to chromosome segregation

“…For example, phosphorylationinduced changes in the activities of proteins that negatively regulate actin fila ment formation, including LIM kinase, cofilin and WD repeatcontaining protein 1 (WDR1), may contribute to an increase in the actin filament turnover rate upon entry into mitosis 35,[47][48][49][50] . Furthermore, the activation of actin filamentbinding proteins, such as ERM (Ezrin, Radixin, Moesin) proteins, brought about by the SLIK kinase 51,52 leads to the physical crosslinking of the actin filaments to proteins embedded in the plasma mem brane 52,53 (FIG.…”