Friday, December 5, 2014 - 2:00pm
Fung Auditorium, Powell-Focht Bioengineering Hall
Kathryn Miller-Jensen, Ph.D.
Assistant Professor of Biomedical Engineering
Uncovering Paracrine Strategies for Coordinating Population Responses Through Single-Cell Analysis
Cell responses are mediated by intermediate signals that are secreted and sensed by the same cells and are subject to significant cell-to-cell heterogeneity. The propagation of these intermediate signals by extracellular signaling impacts the collective cell-population response, but the contribution of autocrine versus paracrine signaling is difficult to analyze. To address this, we have combined multiplexed, microwell single-cell secretion measurements with cell-population data to uncover the role of paracrine signaling in shaping the inflammatory response in human macrophages following toll-like receptor 4 (TLR4) stimulation with lipopolysaccharide (LPS). We demonstrate that loss of paracrine signaling upon single-cell isolation in microwells significantly alters secretion of many LPS-stimulated cytokines. Graphical models of these single-cell “perturbation” data sets specifically uncover dependencies between cytokines in the LPS-stimulated network. Interestingly, tumor necrosis factor-α (TNF), the most highly connected cytokine in the network, exhibits highly heterogeneous secretion, such that a small fraction of cells appear to drive total TNF output in the cell population. Using a computational model fit to our single-cell data, we demonstrate that this small fraction of high secretors can amplify the population response for IL-6 in small cell groups. Overall, our results reveal a novel role for paracrine cell-to-cell communication in coordinating a rapid and reliable innate immune response in spite of underlying cell-to-cell heterogeneity.
Kathryn Miller-Jensen is an Assistant Professor of Biomedical Engineering and Molecular, Cellular, and Developmental Biology at Yale University. Her lab uses experimental and computational approaches to study signaling and transcriptional regulation in response to pathogens, with a focus on activation of latent HIV, as well as innate immune signaling. Her lab is funded by the National Institutes of Health, the National Science Foundation, and the Bill and Melinda Gates Foundation. Kathryn was an NIH NSRA Postdoctoral Fellow at the University of California at Berkeley and she holds a Ph.D. in Chemical Engineering from the Massachusetts Institute of Technology and A.B. and B.E. degrees in Engineering Sciences from Dartmouth College. She is a member of the Biomedical Engineering Society and a former Christine Mirzayan Science and Technology Policy Fellow at the National Academies in Washington, DC.