Wiley Prize in Biomedical Sciences, 2020 Blavatnik National Award in Life Sciences, 2020 Human Frontier Science Program Nakasone Award, 2020 MacArthur Fellow, 2018 Sloan Research Fellowship, 2014 NSF CAREER Award, 2013 NIH New Innovator Award, 2012 Searle Scholar Award, 2012 Helen Hay Whitney Fellow, 2008-2010
Affiliations
Associated Faculty, Department of Molecular Biology Associated Faculty, Lewis-Sigler Institute for Integrative Genomics
Research Interests
? ? Figure 1. Schematic of Brangwynne lab research. Our work is based in the biophysics of intracellular organization, but utilizes those principles in engineering approaches. These engineering approaches (e.g. novel technologies) can then be used to yield new insights into the underlying biophysical principles and functional biologicalThe Brangwynne lab is focused on elucidating the fundamental principles underlying biological organization, with a particular interest in membrane-less organelles/condensates which form within living cells. Despite having no enclosing membrane, these structures localize biomolecules, including both RNA and protein, into distinct subcellular micro-compartments; examples include processing bodies, neuronal granules and germ (P) granules in the cytoplasm, and Cajal bodies, nucleoli, and PML bodies in the nucleus. ?We use experimental approaches together with close theory/computation collaborators to study the role of intracellular phase transitions in the assembly of these structures, and the impact of this phase behavior on the flow of genetic information (for a recent review on intracellular phase separation, see Shin & Brangwynne Science 2017). Our work combines the tools and techniques of soft matter physics and engineering with cutting edge cell and molecular biology methods, including advanced light microscope imaging and analysis. We are also heavily invested in the development of technologies for probing endogenous organelles, as well as engineering entirely new kinds of intracellular organelles for biomedical applications.
The Liquid Nucleome
? ? Figure 2.Schematic of the liquid phases of interest in the nucleus. (B) Two nucleoli from X.laevis oocyte coalesce into a larger sphere. (C) Novel nuclear body in Drosophila oocyte. (D) Gravitational destabilization of nucleoli in X.laevis oocyte; top panels: XY projection, bottom: XZ projection. All adapted from our prior work (Zhu et.al. 2015, Brangwynne et.al. 2011, Feric et.al. 2013).Of the dozens of liquid phase membrane-less bodies in the cell, nuclear bodies are particularly interesting, since they directly interact with and regulate the genome (Fig. 1). Our work to date has focused on nucleoli, the most prominent nuclear body associated with the biogenesis of ribosomes, the protein translation machinery (see e.g. Weber Curr Biol 2015, Berry PNAS 2015, Feric Cell 2016). We are also interested in nuclear bodies associated with the active transcription and processing of other genes, which are associated with condensates such as transcriptional hubs, Cajal bodies, and nuclear speckles. The molecular players underlying phase separation of these structures typically include intrinsically disordered proteins/regions (IDPs/IDRs), and their oligomerization, as well as interactions with RNA. Moreover, DNA is not only restructured in response to RNA/protein-driven phase separation, but itself may phase separate to give rise to higher order genome architecture. The interplay of these effects, and the impacts on biological function, are still largely unclear, and represents a major uncharted universe of non-covalent epigenetic regulation and dynamics. We have various collaborators involved in this work, many of whom are associated with the NIH 4D Nucleome Consortium.
Pathological Protein Aggregation
? ? Figure 3. Adapted from Weber Cell 2012. Biomolecules are capable of not only condensing into a liquid form (LLPS), but can undergo phase transitions into solid like assemblies.The liquid phase nature of intracellular condensates has implications not only for physiological function, but also for its dysregulation in disease. Neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Alzheimers, and Huntington's disease are associated with solid-like protein inclusions comprised of semi-crystalline amyloid fibers. Interestingly, many of the key IDR/LCS proteins found in RNP bodies are also implicated in these pathologies. Moreover, even in healthy cells, RNP bodies do not always appear to be pure liquids, and often exhibit partially solid-like features. In a review in 2012, we suggested that RNP bodies may represent metastable liquid phases, which can transition into more solid-like forms that could underlie the onset of various protein aggregation pathologies (Weber Cell 2012). Work from our own and other groups has recently provided strong evidence in support of this concept, showing that many liquid phase droplets are indeed metastable. For example, after sitting on a coverslip for several hours, droplets of the fungal protein Whi3 begin to nucleate fibers (Zhang Mol Cell 2015), while droplets of the nucleolar protein FIB1 become progressively more gel-like over time, consistent with time-dependent viscoelastic properties in vivo (Feric Cell 2016).
Organelle Engineering
? ? Figure 4. Schematic organelle engineering. Synthetic organelles induced to assemble can potentially concentrate enzymes to enhance the rate of production formation for various biotechnology applications.Membrane-less condensates can play roles within the cell comparable to those described for conventional membrane-bound organelles, including molecular sequestration, facilitating metabolic reactions, and channeling and amplifying intracellular signaling. The name organelle, comes from the fact that these structures are to the cell what our organs are to our bodies. And just as the field of tissue engineering has developed around the potential for organ replacements (i.e. heart, liver, kidney etc.), we are pioneering efforts to develop synthetic organelles for biomedical applications (i.e. organelle diseases) and for various biotechnology applications. This includes efforts to develop actuatable synthetic organelles in human cells, and in synthetic organelles in yeast being pursued in collaboration with the lab of Jose Avalos (Princeton Chemical and Biological Engineering).
Fundamental Biophysics
? ? Figure 5. Intracellular phase diagram. We have begun mapping the first intracellular phase diagrams, utilizing the biomimetic Corelet system (Bracha et.al. Cell 2018). This phase diagram describes the behavior of the oligomerized FUS IDR, and shows features comparable to those well-known in non-living systems.?Our work on intracellular organization spans biology, engineering, and physics, and we believe that thes efforts have the potential to uncover entirely new physics. For example, although our work has revealed that the thermodynamic concept of liquid-liquid phase equilibrium is useful for understanding the cytoplasm/nucleoplasm, living cells are out-of-equilibrium systems. One primary manifestations of this nonequilibrium behavior is the ATP hydrolysis which occurs throughout the cell, associated with activity of a plethora of ATP-dependent enzymes (molecular motors, helicase etc.) – see e.g. Brangwynne JCB 2008, Brangwynne et.al. PNAS 2011, Feric et.al. Cell 2016. ?A second related manifestation of intracellular nonequilibrium is post-translational protein modifications (PTMs), such as phosphorylation of particular IDR residues, which tune the intermolecular interactions underlying phase behavior (for a review, see Brangwynne et.al. Nature Physics 2015). Thus, the phase diagrams that we have been able to map in living cells (e.g. Bracha et.al. Cell 2018) may ultimately reflect and underlying non-equilibrium state. How this nonequilibrium behavior impacts classical features of phase behavior, such as nucleation and growth, spinodal decomposition, and criticality, and its dependence on IDR sequence, remain poorly understood and of great interest to us. Some of this work is being pursued together with our theory/computation collaborators, including Mikko Haataja (Princeton Mechanical Engineering), Ned Wingreen (Princeton Molecular Biology), Rohit Pappu (WUSTL), and Thanos Panagiatopoulos (Princeton Chemical and Biological Engineering).
Selected Publications Shin Y,?Brangwynne CP. Liquid phase condensation in cell physiology and disease.?Science?357(6357)eaaf4382, 2017 Shin Y. , Chang Y-C, Lee D.S.W., Berry J., Sanders D.W., Ronceray P., Wingreen N.S., Haataja M.P.,?Brangwynne CP. Liquid nuclear condensates mechanically sense and restructure the genome.?Cell, 2018 Elbaum-Garfinkle S, Kim Y, Szczepaniak C, Eckmann C, Myong S,? Brangwynne CP. The disordered P granule protein LAF-1 drives phase separation into droplets with tunable viscosity and dynamics. Proceedings of the National Academy of Sciences USA, 112(23):7189-7194, 2015 ?Feric M, Vaidya N, Harmon TS, Mitrea DM, Zhu L, Richardson TM, Kriwacki RW, Pappu RV,?Brangwynne CP.?Coexisting liquid phases underlie nucleolar sub-compartments.?Cell, 165(7):1686-1697, 2016 Brangwynne CP, Eckmann CR, Courson DS, Rybarska A, Hoege C, Gharakhani J, Jülicher F, Hyman AA. Germline P granules are liquid droplets that localize by controlled dissolution/condensation. Science,? 324: 1729-1732, 2009