Cell Motility and Cytokinesis

Talk Overview

Pollard begins with a brief history of the proteins involved in cellular motility, and the various factors involved in regulating actin filament turnover and cytokinesis.  He focuses on the role of the Arp2/3 protein complex in nucleating the growth of the branched actin filaments found at the leading edge of a motile cell. Structural and biochemical studies allowed Pollard and his colleagues to formulate a model for how actin polymerization can provide the force to push the cell membrane forward.

In his second talk, Pollard explains why the fission yeast S. pombe is an excellent model to study actin-mediated processes. Fluorescently labeled actin-binding proteins allowed Pollard and his colleagues to follow actual cellular events and compare them with their mathematical model. Adjusting the model so it matched the experimental data provided insight into how actin assembly and turnover could produce the force needed for cells to move or undergo endocytosis.

Cytokinesis is the process by which a contractile ring forms around the middle of a cell and squeezes to divide it into two daughter cells. Although it has been known since the 1970s that the contractile ring contains actin and myosin, it turns out that there are over 100 other proteins involved in cytokinesis. In fission yeast, conditional and deletion mutants of many cytokinesis genes are available, many cytokinesis proteins have been labeled with fluorescent tags so they can be followed over time in live cells, and biochemical characterization of proteins has informed computer models.  In his third talk, Pollard discusses the data that have given rise to the latest model for how the contractile ring forms and is regulated.

Speaker Bio

Thomas Pollard

Tom Pollard is the Sterling Professor of Molecular, Cellular and Developmental Biology at Yale University.  He received his BA from Pomona College and his MD from Harvard Medical School.  He was a Professor at the Johns Hopkins University School of Medicine from 1977-1996 and President of the Salk Institute in San Diego from 1996-2000.  He… Continue Reading