MONDAY, April 20
Condensed Matter Physics Seminar, 4:00 PM - 5:00 PM, 107 Downs
"Feedback Regulation and Dosage Compensation in Gene Networks," Murat Acar, Caltech. More info: CMP

Abstract:
Feedback-mediated regulation of gene expression is ubiquitous in gene networks. Positive feedback structures can give rise to bistability or hysteresis while negative feedback loops can help cells tune the frequency of cellular switching between different gene expression states. By using the galactose utilization pathway of the yeast Saccharomyces cerevisiae as a model gene network, we experimentally quantified the contribution of different feedback topologies on gene network activity. We re-programmed the rates of phenotypic switching between the ON and OFF states of the network with time scales ranging from hours to months. Next, in order to understand how the activity of the network is affected by its size (or dosage), we combinatorially constructed diploid 'network mutant' strains in which either one or two copies of the four regulatory genes (GAL2, GAL3, GAL4, and GAL80) of the network were present. Our results demonstrate that the activity of the galactose regulatory network is robust to variations in network size. Cells could use such a network property to better cope with potentially detrimental and sudden variations in network size caused, for example, by genome duplication events.

Sponsored by: Professor Mike Cross