Speaker : Pr Thomas POLLARD
Professor of Molecular Cellular & Developmental Biology, Molecular Biophysics & Biochemistry of Cell Biology, Yale University, USA
Hosted by Daniel RIVELINE
We combine biochemical analysis of proteins, quantitative and super resolution microscopy of live cells and simulations of mathematical models to study the formation, constriction and disassembly the cytokinetic contractile ring in fission yeast. The proteins that organize the contractile ring form different structures at each stage of the cell cycle. During interphase two types of punctate protein structures arise in separate locations in the cortex and join each other around the equator of the cell by a diffuse and capture mechanism to form « nodes », the precursors of the cytokinetic contractile ring (Akamatsu et al. 2014).
During mitosis nodes grow actin filaments and a search, capture, pull and release mechanism organizes the nodes into the contractile ring (Vavylonis et al. 2008). The contractile ring constricts in coordination with growth of the cell wall into the cleavage furrow. A stochastic model based on the numbers and properties of the main proteins self-assembles and continuously remodels the contractile ring, which produces tension similar to that observed in cells (Stachowiak et al., 2014). These models account of the physical basis of the main events in cytokinesis across the entire cell cycle.