Title : "Beyond the genetic code: how a shape-shifting genome controls cell fate"
Speaker : Dr. Geeta Narlikar, Professor of Biochemistry and Biophysics, Lewis and Ruth Cozen Chair I, University of California, San Francisco, USA
Abstract: Different cell types in a given animal, such as heart cells and brain cells display different behaviors because they express different sets of genes. Yet, they all have DNA with essentially the same sequence and thus the same set of genes. How is it that the same DNA is used to generate different cell types? Which genes are on and which genes are off is controlled in part by how their underlying DNA sequences are packaged. DNA is packaged by wrapping it around specific proteins called histones to generate bead-like structures called nucleosomes. Strings of nucleosomes are then further folded to condense the underlying DNA and make it less accessible. Structures called heterochromatin are thought to be particularly effective at compacting strings of nucleosomes and turning off the underlying genes. A few years ago we discovered that nucleosomes, rather than acting as rigid packaging units act as shape-shifters to regulate access to the wrapped DNA. Around the same time we also found that proteins named HP1 proteins, which are core components of heterochromatin, can sequester packaged DNA into phase-separated droplets. Within these droplets the HP1 molecules are dynamic and display liquid-like properties. In my talk I will discuss the experiments that led to these findings. I will also discuss how these unexpected biophysical properties of the packaged genome are leading to new ways of conceptualizing genome regulation.
About the Speaker: Prof. Geeta Narlikar is the Professor of Biochemistry and Biophysics at the University of California, San Francisco. She is a pioneer in the field of chromatin biology where she discovered how molecular machines reorganise our genome. She studies the regulation of folding and compartmentalization of the genome that generates the many cell types that make up our body. She obtained her MSc in Chemistry from IIT Bombay in 1992 and PhD from Stanford University in 1998. She carried out postdoctoral research at the Harvard Medical School. She received distinguished alumnus award in 2018 from IIT Bombay. Prof. Narlikar's scientific work has been recognized by different awards during the course of her faculty career. These include the Beckman Young Investigator Award (2006), the Leukemia and Lymphoma Society Scholar Award (2008), the Outstanding Faculty Mentorship Award by the UCSF Graduate Students Association (2011) and the Deleage Prize awarded by the Deleage foundation (2017). Since 2017, Professor Narlikar has been appointed to the Lewis and Ruth Cozen Chair.