Friday, December 8
9:30 AM - 4:00 PM EST
Skylight Room and via Zoom
watch the lectures online
9:30 AM
Coffee and bagels
10:00 AM - 11:30 AM
Deciphering the form and function of the 3D genome
Zhe J. Liu
HHMI Janelia Research Campus
Deconstructing the mechanism by which the 3D genome encodes genetic information to generate diverse cell types during animal development is a major challenge in biology. In this talk, I will discuss our latest effort on devising advanced imaging and genomic tools to quantitatively analyzes gene regulatory mechanisms at the single-cell, single-molecule level to discover how stereotypical gene expression programs during normal development as well as altered states in diseases emerge from seemly stochastic molecular events in the cell. Particularly, by single-molecule spatial imaging , we recently found that, instead of dictating population-wide gene expression levels, 3D genome topology safeguards long-distance gene co-expression programs in single cells.
11:30 AM - 12:00 PM
Break
12:00 PM - 1:30 PM
Transcription factor dynamics in gene expression: the long and short of it
Arpita Upadhyaya
University of Maryland
Transcription factors (TFs) regulate gene expression by binding to specific DNA sequences within a complex and heterogenous chromatin environment to assemble transcriptional machinery at specific genomic loci. The mechanisms by which TFs bind to their target sequences on dynamic chromatin to regulate gene expression remains elusive. We used single-molecule tracking to directly measure the interaction dynamics of a broad spectrum of transcription factors in live cells. We found that TFs follow power-law distributed binding times, suggesting that the prevalent model of specific and non-specific TF/chromatin interactions is incomplete. Using machine-learning based analysis of single molecule mobility, we found that a diverse set of transcription factors, transcriptional co-regulators, architectural proteins, and remodelers exhibit two distinct low-mobility bound states, reflecting the mobility of the underlying chromatin. We use mutational analysis to dissect the origins of these low mobility states. Together, our results elucidate how TF and chromatin mobility regulates transcriptional activation in mammalian cells.
1:30 PM - 2:30 PM
Lunch
2:30 PM - 4:00 PM
Ultralong-term, real-time tracking of single cargoes in living neurons
Chunte Sam Peng
Massachusetts Institute of Technology
Broad Institute
Cytoplasmic dynein is essential for intracellular transport. Despite extensive in vitro characterizations, how the dynein motors work collectively to transport vesicles and how they step in live cells remains elusive because of the much faster speed of dynein under physiological conditions. To dissect the molecular mechanism and dynamics of dynein, we developed novel optical probes which enabled long-term single particle tracking with high spatiotemporal resolutions. We found that the number of active dynein motors transporting the cargo switched stochastically from one to five pairs during the long-range transport. Our very bright optical probes allowed the observation of individual molecular steps. The dwell time between steps was found to be described by two equal and temperature-dependent rate constants. This finding suggests that two ATP molecules were hydrolyzed sequentially during each dynein step. Our observations shed new light on the chemomechanical cycle of dynein in living cells.
Organized by Thomas Gregor and Kevin Keomanee-Dizon (Princeton University). Sponsored in part by the NSF Center for the Physics of Biological Function, a joint effort of Princeton University and the CUNY Graduate Center.