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Phase Separation

Available via

WEBINAR

Phase Separation in Biology and Disease

Wednesday, February 20, 2019, 8:30 AM - 5:00 PM

The New York Academy of Sciences, 7 World Trade Center, 250 Greenwich St Fl 40, New York

Presented By

The Chemical Biology Discussion Group

The New York Academy of Sciences

 

Liquid-liquid phase separation of cytoplasmic and nuclear components into biomolecular condensates is emerging as a fundamental mechanism of cellular organization. These condensates are spatially segregated, but open systems, which can serve as specialized regions for biochemical reactions, dynamically sequester components or act as organizational hubs for signaling networks.

Phase separation regulates processes as diverse as transcription, stress granule formation and actin polymerization. Moreover, an accumulating body of evidence suggests that dysregulation of these phase transitions may contribute to neurodegenerative diseases, including ALS and prion diseases, as well as to cancer.

This one day symposium will bring together scientists from academia and industry to dissect the latest advances in the field of biological phase separation and discuss the implications for human disease.

Registration

Member
By 01/11/2019
$90
After 01/11/2019
$130
Nonmember Academia, Faculty, etc.
By 01/11/2019
$180
After 01/11/2019
$260
Nonmember Corporate, Other
By 01/11/2019
$250
After 01/11/2019
$350
Nonmember Not for Profit
By 01/11/2019
$180
After 01/11/2019
$260
Nonmember Student, Undergrad, Grad, Fellow
By 01/11/2019
$100
After 01/11/2019
$145
Member Student, Post-Doc, Fellow
By 01/11/2019
$50
After 01/11/2019
$70
Member
$30
Nonmember Academia, Faculty, etc.
$65
Nonmember Corporate, Other
$85
Nonmember Not for Profit
$65
Nonmember Student, Undergrad, Grad, Fellow
$45
Member Student, Post-Doc, Fellow
$15
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Scientific Organizing Committee

Clifford Brangwynne
Clifford Brangwynne, PhD,
Princeton University
Jason Imbriglio, PhD,  Merck
Jason Imbriglio, PhD,
Merck
Neal Zondlo, PhD,  University of Delaware
Neal Zondlo, PhD,
University of Delaware
Sara Donnelly, PhD, The New York Academy of Sciences
Sara Donnelly, PhD, The New York Academy of Sciences
Sonya Dougal, PhD, The New York Academy of Sciences
Sonya Dougal, PhD, The New York Academy of Sciences

Speakers

Clifford Brangwynne, PhD,  Princeton University
Clifford Brangwynne, PhD,
Princeton University
Zhijian "James" Chen, PhD,  University of Texas, Southwestern
Zhijian "James" Chen, PhD,
University of Texas, Southwestern
Geraldine Seydoux, PhD,  Johns Hopkins School of Medicine
Geraldine Seydoux, PhD,
Johns Hopkins School of Medicine
Abby Dernburg, PhD,  University of California, Berkeley
Abby Dernburg, PhD,
University of California, Berkeley
Rohit Pappu, PhD  Washington University in St. Louis
Rohit Pappu, PhD
Washington University in St. Louis
Tanja Mittag
Tanja Mittag, PhD

St. Jude Children's Research Hospital

Nicolas Fawzi, PhD,  Brown University
Nicolas Fawzi, PhD,
Brown University
Martin Jonikas, PhD,  Princeton University
Martin Jonikas, PhD,
Princeton University
David Cowburn, PhD, DSc,  Albert Einstein College of Medicine
David Cowburn, PhD, DSc,
Albert Einstein College of Medicine





Wednesday

February 20, 2019

8:30 AM

Continental Breakfast and Registration

9:00 AM

Introduction and Welcome Remarks

Speakers

Sara Donnelly, PhD
The New York Academy of Sciences
Neal Zondlo, PhD
University of Delaware

Session 1: Composition and Regulation of Biomolecular Condensates

Session Chairperson
Neal Zondlo
9:15 AM

Assembly, Properties, and Function of Liquid States of Biological Matter

Speaker

Clifford Brangwynne, PhD
Princeton University
9:45 AM

Regulation of RNA Granule Dynamics by Intrinsically-disordered Proteins

Speaker

Geraldine Seydoux, PhD
Johns Hopkins School of Medicine

RNA granules are RNA-protein condensates that form in the cytoplasm or nucleoplasm of cells. We are studying the P granules of C. elegans as a model to uncover principles of RNA granule assembly and function. We have identified a small family of intrinsically-disordered proteins (MEGs) that drive P granule assembly in C. elegans embryos. I will present our recent findings on how the MEGs recruit mRNAs to P granules.

10:15 AM

Networking Coffee Break

10:45 AM

Characterization of Multivalent Interactions of Proteins

Speaker

David Cowburn, PhD, DSc
Albert Einstein College of Medicine

Intrinsically disordered proteins (IDPs) play important roles in many biological systems, including phase
seperated low complexity domain. Given the vast conformational space that IDPs can explore, the
thermodynamics of the interactions with their partners is closely linked to their biological functions.
Intrinsically disordered regions of Phe–Gly nucleoporins (FG Nups) that contain multiple
phenylalanine–glycine repeats are of particular interest, as their interactions with transport factors (TFs)
underlie the paradoxically rapid yet also highly selective transport ofmacromoleculesmediated bythe
nuclear pore complex. We used NMR and isothermal titration calorimetry to thermodynamically
characterize these multivalent interactions. These analyses revealed that a combination of low FG
motif affinity and the enthalpy–entropy balance prevents high avidity interaction between FG Nups and
TFs, whereas the large number of FG motifs promotes frequent FG–TF contacts, resulting in enhanced
selectivity. Our thermodynamic model underlines the importance of functional disorder of FG Nups. It
helps explain the rapid and selective translocation of TFs through the nuclear pore complex and further
expands our understanding of the mechanisms of “fuzzy” interactions involving IDPs.

11:15 AM

Multivalency and Disorder as Drivers of Protein Phase Separation

Speaker

Rohit Pappu, PhD
Washington University in St. Louis

This talk will present findings based on a stickers and spacers model for proteins that drive phase separation of proteins with multivalency of adhesive motifs / domains interspersed by spacers.

Session 2: Data Blitz Talks

Session Chairperson
Neal Zondlo
11:45 AM

Short Talks Selected from Submitted Abstracts

12:00 PM

Networking Lunch and Poster Session

Speakers

Odd Numbered Posters
12:30 PM - 1:00 PM
Even Numbered Posters
1:00 PM - 1:30 PM

Session 3: Regulation of Physiological Processes by Phase Separation

Session Chairperson
Clifford Brangwynne
1:30 PM

DNA-induced Liquid Phase Condensation of cGAS Activates Innate Immune Signaling

Speaker

Zhijian "James" Chen, PhD
University of Texas Southwestern
2:00 PM

Phase Separation in Photosynthesis

Speaker

Martin Jonikas, PhD
Princeton University
2:30 PM

Phase Separation Mediates Intracellular Pattern Formation

Speaker

Abby Dernberg, PhD
University of California Berkeley

The cell division process of meiosis partitions a diploid genome to produce haploid cells, and is essential for sexual reproduction. During meiotic prophase, each chromosome pairs with its homolog. Paired homologs then “zipper up” via assembly of a unique protein polymer, the synaptonemal complex (SC), along their interface. Through in vivo imaging in Caenorhabditis elegans, we discovered that the SC behaves as a liquid crystal, and have been investigating the implications of this finding.

A longstanding mystery has been the regulation of meiotic recombination: each pair of chromosomes must undergo at least one crossover, but the total number of crossovers is typically very low, often just one per pair. The SC plays a crucial role in crossover control. We have now found that ZHP-1–4, members of a widely conserved family of meiotic RING finger proteins, diffuse within the SC and interact with components anchored at recombination intermediates to pattern crossovers.

In 1952, the mathematician Alan Turing first proposed that biological patterns might arise through coupled feed-forward and feedback interactions within a diffusive medium. Such “reaction-diffusion” mechanisms can operate on any spatial scale. They are thought to underlie pigmentation patterns and the regular spacing of hair, feathers, and fish scales, and have also been proposed to mediate intracellular patterning and symmetry breaking. Liquid-liquid (or liquid crystalline) phase separation (LLPS) gives rise to subcellular compartments of varying geometries that concentrate biomolecules and impose boundaries to their diffusion. We propose that LLPS may create conditions that enable formation of diverse subcellular patterns.

Session 4: Phase Separation in Disease

Session Chairperson
Jason Imbriglo
3:00 PM

Networking Coffee Break

3:30 PM

Phase Separation for Proteostasis in Normal and Cancerous Cells

Speaker

Tanja Mittag, PhD
St. Jude Children's Research Hospital

Liquid–liquid phase separation is the biophysical driving force for the formation of membrane-less organelles in cells, such as stress granules, nucleoli and nuclear speckles. Current open questions are: (i) How is phase separation propensity encoded in the protein sequence, (ii) are dense liquid droplets used as reaction compartments in the cell, and (iii) is physiological phase separation disrupted in disease states? To address these, we study the tumor suppressor Speckle-type POZ protein (SPOP), a substrate adaptor of a ubiquitin ligase, which localizes to different liquid membrane-less organelles in the cell nucleus. In these organelles, SPOP encounters its substrates but its recruitment mechanism to the organelles is not understood. Here, we show that SPOP undergoes LLPS with substrate proteins, and that this mechanism underlies its recruitment to membrane-less organelles. Multivalency of SPOP and substrate for each other drive their ability to phase separate. We present evidence that the SPOP/substrate assemblies are active ubiquitination compartments in vitro and in cells. SPOP cancer mutations reduce the propensity for phase separation. We propose that SPOP has evolved a propensity for phase separation in order to target substrates localized in membrane-less compartments. Using phase separation for proteostasis may allow setting an upper limit for substrate protein levels in cells.

Coauthors: Jill J. Bouchard[1], Joel H. Otero[1], Daniel C. Scott[1], Elzbieta Szulc[2], Erik W. Martin[1], Nafiseh Sabri[1], Daniele Granata[3], Kresten Lindorff-Larsen[3], Xavier Salvatella[2,4], Brenda A. Schulman[5,6].

1. St. Jude Children’s Research Hospital, Memphis.
2. The Barcelona Institute of Science and Technology, Barcelona.
3. University of Copenhagen.
4. ICREA, Barcelona.
5. Max-Planck Institute of Biochemistry, Martinsried/Munich.
6. Howard Hughes Medical Institute, St. Jude Children's Research Hospital, Memphis.

4:00 PM

Functional and Pathological RNA-binding Protein Phase Separation with Atomic Detail

Speaker

Nicolas Fawzi, PhD
Brown University

Cells use various mechanisms to organize reactions and sequester proteins, RNA, and chromatin for transcription, processing, and localization. One emerging mechanism is liquid-liquid phase separation mediated by the association of the disordered domains of RNA binding proteins. RNA-binding proteins FUS, TDP-43, and hnRNPA2 are all associated with RNA granule assembly and all form inclusions in amyotrophic lateral sclerosis and multisystem proteinopathy, respectively. Using these proteins as models, we probe their molecular structure along the assembly pathway and the structural changes caused by disease mutations and post-translational modifications. Using nuclear magnetic resonance (NMR) spectroscopy and molecular simulation, we see their structure and interactions with atomic resolution. These findings are paired with microscopy and turbidity experiments and cell assays to assess the effect of posttranslational modifications and mutations on phase separation, aggregation, toxicity and splicing function. We find that low complexity domains remain predominantly unstructured both before and after phase separation. The exception is TDP-43 where phase separation and protein function is enhanced by a globular domain and an alphahelical region whose helical extent increases and extends upon phase separation. Arginine methylation and phosphorylation disrupts phase separation, aggregation, and cellular toxicity. Our work points to the potential for post-translational modification to alter assembly, function, and pathological interactions of disease-associated disordered domains.

4:30 PM

Closing Remarks

Speaker

Jason Imbriglio, PhD
Merck
4:35 PM

Networking Reception and Poster Session

5:00 PM

F1000 Poster Prize Presentation

Speaker

Clifford Brangwynne, PhD
Princeton University
5:35 PM

Adjourn