There’s a time and a place: Biological discovery with spatially and temporally engineered materials
A key goal within the mechanobiology field has been to understand how biophysical properties of the microenvironment control cellular mechanics and phenotype. Historically, the vast majority of discovery in this area has relied on static and spatially uniform extracellular matrix platforms. While such approaches have been enormously powerful, they are often poorly suited to probing the dynamic mechanical interplay between a cell and its microenvironment. At the same time, these platforms paradoxically create large heterogeneities in cell size, shape, and cytoarchitecture that can make it challenging to quantify regulatory relationships. In this presentation I will discuss recent efforts my colleagues and I have made to exploit next-generation matrix platforms whose material properties may be controlled in both time and space. First, I will discuss our use of a polymer hydrogel system that may be reversibly stiffened and softened through the use of oligonucleotide-based crosslinks, which we have used to identify a critical time window for mechanosensitive neural stem cell lineage commitment. This system has also led us to discover an unexpected and non-canonical role for the transcriptional co-activator YAP in determining cell fate. Second, I will describe our combined use of single-cell photopatterning and femtosecond laser nanosurgery to probe the viscoelastic properties of actomyosin stress fibers with tightly standardized positions and lengths. This approach has allowed us to elucidate relationships between fiber elastic energy and length with unprecedented clarity, as well as gain new insight into how tension within a single fiber is governed by the properties of the surrounding cytoskeletal network. The models we develop in these stereotyped settings allow us to explain propagation of tension in more physiological settings, including during EGF-stimulated migration and the coupling of cytoskeletal tension across cells within a monolayer.
Sanjay Kumar, M.D., Ph.D., is Professor and Associate Chair of Bioengineering at UC Berkeley. He earned his B.S. in Chemical Engineering from the University of Minnesota in 1996, and his M.D. and Ph.D. in Molecular Biophysics from Johns Hopkins University in 2003. After completing an NIH Postdoctoral Fellowship at Children’s Hospital Boston and Harvard Medical School, he joined the faculty of the UC Berkeley Department of Bioengineering in 2005. He is also Professor of Chemical and Biomolecular Engineering at UC Berkeley and a Faculty Scientist in the Biological Systems & Engineering Division of Lawrence Berkeley National Laboratory. Dr. Kumar and his research group have been fortunate to receive a number of honors, including the Presidential Early Career Award for Scientists and Engineers (PECASE), The NIH Director's New Innovator Award, The Arnold and Mabel Beckman Young Investigator Award, the NSF CAREER Award, and the Stem Cells Young Investigator Award. He has also received awards by student vote for Outstanding Graduate Advising and Undergraduate Teaching. Dr. Kumar is an elected Fellow of AIMBE and BMES.
Molecular Engineering and Sciences Seminar Series
This weekly seminar brings together students, faculty and invited guests from various disciplines across campus to explore current trends in molecular engineering and nanotechnology. It is a forum for active interdisciplinary discussions. These talks are open to the public and attract a diverse audience of students and faculty.