Crosstalk between NDR kinase pathways coordinates cell cycle dependent actin rearrangements

Abstract

Regulation of cytoskeletal remodeling is essential for cell cycle transitions. In fission yeast two NDR kinase signaling cascades, MOR and SIN, regulate the actin cytoskeleton to promote polarized growth during interphase and cytokinesis respectively. Our understanding of how these signaling pathways are coordinated to assist transition between the two cell-cycle stages is limited. Here, we review work from our laboratory, which reveals that cross talk between the SIN and MOR pathways is required for inhibition of interphase polarity programs during cytokinesis. Given the conservation of NDR kinase signaling pathways, our results may define general mechanisms by which these pathways are coordinated in higher organisms.

Figure 1

Conservation of NDR kinase pathways across species. Members of the Ste-20 like kinase family (Sid1, Nak1, Hpo, Mst1/2, Mst3) and the Nuclear Dbf2-related kinase family (Sid2, Orb6, Wts, Trc, Lats1/2, Ndr1/2) constitute the core of the NDR kinase signaling pathways in S. pombe, D. melanogaster (Fly), and mammals. This figure illustrates the cellular functions performed by these pathways in their respective organisms.

Figure 2

A dual role for the SIN in MOR pathway regulation. The SIN mediated regulation of MOR during mitosis appears to have two distinct cell cycle dependent effects on MOR function. While the SIN inhibits MOR activity during mitosis to keep MOR from interfering with cytokinesis, it may also play a role in enhancing MOR activity during the following interphase in order promote polarized growth.