March 23, 2018, Eduardo Sontag, Northeastern University

Friday, March 23, 2018, 3pm-4pm
8 St. Mary’s Street, PHO 211
Refreshments at 2:45pm

Eduardo Sontag
Northeastern University 

Dynamic Response Phenotypes in Systems Biology: Scale-Invariance and Monotone I/O Systems

Among the central questions in systems biology are those of understanding the roles of, and interactions among, signal transduction pathways and feedback loops. This talk focuses on “dynamic phenotypes” characterized by input/output responses to external inputs in addressing such issues, using fold-change detection and monotone architectures as case studies.

An ubiquitous property of sensory systems is “adaptation”: a step increase in stimulus triggers an initial change in a biochemical or physiological response, followed by a more gradual relaxation toward a basal, pre-stimulus level. Adaptation helps maintain essential variables within acceptable bounds and allows organisms to readjust themselves to an optimum and non-saturating sensitivity range when faced with a prolonged change in their environment. It has been recently observed that some adapting systems, ranging from bacterial chemotaxis pathways to signal transduction mechanisms in eukaryotes, enjoy a remarkable additional feature: scale invariance or “fold change detection” meaning that the initial, transient behavior remains approximately the same even when the background signal level is scaled. This talk will review the biological phenomenon, and formulate a theoretical framework leading to a general theorem characterizing scale invariant behavior by equivariant actions on sets of vector fields that satisfy appropriate Lie-algebraic nondegeneracy conditions. The theorem allows one to make experimentally testable predictions, and the presentation will discuss the validation of these predictions using genetically engineered bacteria and microfluidic devices, as well their use as a “dynamical phenotype” for model invalidation. The talk will also include some speculative remarks about the role of the shape of transient responses in immune system self/other recognition and in cancer immunotherapy, as well as a brief discussion of how control-theoretic structures such as differential positivity (monotonicity) have been experimentally employed together with experimental data in order to elucidating mechanisms for stress responses and chemosensing.

Eduardo Sontag’s major current research interests lie in several areas of control and dynamical systems theory, systems molecular biology, cancer and immunology, and computational biology.

Dr. Sontag received his Licenciado degree from the Mathematics Department at the University of Buenos Aires in 1972, and his Ph.D. (Mathematics) under Rudolf E. Kalman at the University of Florida, in 1977. From 1977 to 2017, he was with the Department of Mathematics at Rutgers, The State University of New Jersey, where he was a Distinguished Professor of Mathematics as well as a Member of the Graduate Faculty of the Department of Computer Science and the Graduate Faculty of the Department of Electrical and Computer Engineering, and a Member of the Rutgers Cancer Institute of NJ. In addition, Dr. Sontag served as the head of the undergraduate Biomathematics Interdisciplinary Major, Director of the Center for Quantitative Biology, and Director of Graduate Studies of the Institute for Quantitative Biomedicine. In January 2018, Dr. Sontag was appointed as a University Distinguished Professor in the Department of Electrical and Computer Engineering and the Department of BioEngineering at Northeastern University.

Sontag has authored over five hundred research papers and monographs and book chapters in the above areas with over 41,000 citations and an h-index of 88.

Sontag is in the Editorial Board of several journals, including: IET Proceedings Systems Biology, Synthetic and Systems Biology, International Journal of Biological Sciences, and Journal of Computer and Systems Sciences, and is a former Board member of SIAM Review, IEEE Transactions in Automatic Control, Systems and Control Letters, Dynamics and Control, Neurocomputing, Neural Networks, Neural Computing Surveys, Control-Theory and Advanced Technology, Nonlinear Analysis: Hybrid Systems, and Control, Optimization and the Calculus of Variations. In addition, he is a co-founder and co-Managing Editor of the Springer journal MCSS (Mathematics of Control, Signals, and Systems).

Sontag is an IEEE Fellow, an AMS Fellow, a SIAM Fellow, and a Fellow of the International Federation of Automatic Control. He has been Program Director and Vice-Chair of the Activity Group in Control and Systems Theory of SIAM, and member of several committees at SIAM and the AMS, including Chair of the Committee on Human Rights of Mathematicians of the latter. He was awarded the Reid Prize in Mathematics in 2001, the 2002 Hendrik W. Bode Lecture Prize and the 2011 Control Systems Field Award from the IEEE, the 2002 Board of Trustees Award for Excellence in Research from Rutgers, and the 2005 Teacher/Scholar Award from Rutgers.

Faculty Host: Ioannis Paschalidis
Student Host: Sean Sanchez