Defining elements in contractile ring assembly

Posted by vuit_admin on Friday, March 27, 2009 in Uncategorized .

Vanderbilt Reporter, Lords of the contractile ring

Cell division requires the formation of a contractile ring. While many protein components of this ring are known, how they interact with each other and with the plasma membrane remains unclear.

Rachel Roberts-Galbraith, Kathy Gould, Ph.D., and colleagues are studying these ring proteins in yeast. One such protein, Cdc15, has two “domains” that carry out different functions – the F-BAR domain, which binds and curves the plasma membrane, and the SH3 domain, which had not been characterized.

In the January Journal of Cell Biology, the researchers show that the SH3 domains of Cdc15 and of another member of the same protein family (Imp2) recruit other proteins (including a paxillin-like protein Pxl1 and a highly conserved C2-domain protein Fic1) to the contractile ring. Together, Pxl1 and Fic1 add structural integrity to the contractile ring and prevent it from fragmenting during cell division. The SH3 domains of Cdc15 and Imp2 overlap in function, and the authors suggest that this redundancy is essential for division of the cellular contents.

— Melissa Marino, Vanderbilt Reporter

See Also PubMed Article

Roberts-Galbraith, R.H., Chen, J.-S., Wang, J. and Gould, K.L. (2009) The SH3 domains of two PCH family members cooperate in construction of the Schizosaccharomyces pombe contractile ring. J. Cell Biol. 184:113-127.

Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.

Schizosaccharomyces pombe cdc15 homology (PCH) family members participate in many cellular processes by bridging the plasma membrane and cytoskeleton. Their F-BAR domains bind and curve membranes, whereas other domains, typically SH3 domains, are expected to provide cytoskeletal links. We tested this prevailing model of functional division in the founding member of the family, Cdc15, which is essential for cytokinesis in S. pombe, and in the related PCH protein, Imp2. We find that the distinct functions of Imp2 and Cdc15 are SH3 domain independent. However, the Cdc15 and Imp2 SH3 domains share an essential role in recruiting proteins to the contractile ring, including Pxl1 and Fic1. Together, Pxl1 and Fic1, a previously uncharacterized C2 domain protein, add structural integrity to the contractile ring and prevent it from fragmenting during division. Our data indicate that the F-BAR proteins Cdc15 and Imp2 contribute to a single biological process with both distinct and overlapping functions.