2017.3.6. Ratio sensing and signal decomposition in the response of yeast to mixtures of sugars
题 目： Ratio sensing and signal decomposition in the response of yeast to mixtures of sugars
报告人： Dr. Michael Springer
Associate Professor, Systems Biology Department, Harvard Medical School, Boston, MA
时 间： 2017年3月6日13：00-14：00
地 点： 北京大学老化学楼东配楼101报告厅
主持人： 汤超 教授
We use the response of yeast to galactose, one of the best-studied Eukaryotic signaling pathways, as a model for understanding how cells integrate multiple signals from their environment. We have uncovered several previously unrecognized features of GAL signaling： 1) cells respond to the ratio of glucose and galactose and 2) the strength of induction and the decision to induce are decomposable and regulated independently. We have evidence that the ratiometric sensing is set by the plasma membrane transporters and therefore suggest that the more than twenty 'passive' hexose transporters may be playing an integral role in signal processing. Additionally, the mathematical decomposition of the response appears to be matched by a genetic decomposition that allow cells to independently select the strength of induction and decision to induce. Correspondingly, we find a significant amount of variation in natural populations in the decision to induce the GAL pathway. We can map the majority of this variation to changes in a single locus, GAL3. In contrast to this, we find that >1000 genes can affect the GAL pathway, highlighting the differences between natural variation and mutational potential.
Dr. Michael Springer is an associate professor in systems biology department at Harvard medical School. He received a dual degree in biological sciences and chemistry in 1996. Later, he got his PhD degree in cell biology under Erin O’Shea’s mentorship at UCSF in 2003. And then took up a postdoc in systems biology with Marc Kirschner Bela at Harvard medical school. His lab focuses on understanding a facet of this large problem： how cells quantitatively process and appropriately respond to their environment, including how mutations and evolution alter response. They use yeast as a model system for signal integration, as this high throughput system provides a nearly unparalleled ability to attack this problem from many angles and interpret the results in the context of a well understood system.