scholarly journals Condensation of pericentrin proteins in human cells illuminates phase separation in centrosome assembly

2021 ◽  
Author(s):  
Xueer Jiang ◽  
Dac Bang Tam Ho ◽  
Karan Mahe ◽  
Jennielee Mia ◽  
Guadalupe Sepulveda ◽  
...  
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Chromosome Segregation ◽  
Low Complexity ◽  
Coiled Coils ◽  
Human Cells ◽  
Terminal Portion ◽  
Pericentriolar Material ◽  
Liquid Liquid Phase Separation ◽  
Early Mitosis

At the onset of mitosis, centrosomes expand the pericentriolar material (PCM) to maximize their microtubule-organizing activity. This step, termed centrosome maturation, ensures proper spindle organization and faithful chromosome segregation. However, as the centrosome expands, how PCM proteins are recruited and held together without membrane enclosure remains elusive. We found that endogenously expressed pericentrin (PCNT), a conserved PCM scaffold protein, condenses into dynamic granules during late G2/early mitosis before incorporating into mitotic centrosomes. Furthermore, the N-terminal portion of PCNT—enriched with conserved coiled-coils (CCs) and low-complexity regions (LCRs)—phase separates into dynamic condensates that selectively recruit PCM proteins and nucleate microtubules in cells. We propose that CCs and LCRs, two prevalent sequence features in the centrosomal proteome, are preserved under evolutionary pressure in part to mediate liquid-liquid phase separation, a process that bestows upon the centrosome distinct properties critical for its assembly and functions.

scholarly journals Condensation of pericentrin proteins in human cells illuminates phase separation in centrosome assembly

2020 ◽  
Author(s):  
Xueer Jiang ◽  
Dac Bang Tam Ho ◽  
Karan Mahe ◽  
Jennielee Mia ◽  
Guadalupe Sepulveda ◽  
...  
Keyword(s):  
Phase Separation ◽  
Lipid Membrane ◽  
Low Complexity ◽  
Terminal Segment ◽  
Coiled Coils ◽  
Human Cells ◽  
Mitotic Spindles ◽  
Pericentriolar Material ◽  
Cultured Human Cells ◽  
Early Mitosis

AbstractMitotic centrosomes are complex membraneless organelles that guide the formation of mitotic spindles to ensure faithful cell division. They are formed by timely expansion of the pericentriolar material (PCM) around the centrioles at the onset of mitosis. How PCM proteins are recruited and held together without a lipid membrane remains elusive. Here we found that endogenously expressed pericentrin (PCNT), a conserved PCM scaffold protein, condenses into liquid-like granules during early mitosis in cultured human cells. Furthermore, the N-terminal segment of PCNT, enriched with conserved coiled-coils and low-complexity regions (LCRs), undergoes phase separation. These PCNT “condensates” selectively recruit PCM components and nucleate microtubules in cells. We propose that coiled-coils and LCRs, two prevalent sequence features in the centrosomal proteome, are preserved under evolutionary pressure to drive phase separation, a process that bestows upon the centrosome a distinct material property critical for its assembly and functions.

scholarly journals Liquid–Liquid Phase Separation Enhances TDP-43 LCD Aggregation but Delays Seeded Aggregation

Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 548
Author(s):  
Donya Pakravan ◽  
Emiel Michiels ◽  
Anna Bratek-Skicki ◽  
Mathias De Decker ◽  
Joris Van Lindt ◽  
...  
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Hydrophobic Interactions ◽  
Low Complexity ◽  
Liquid Phase Separation ◽  
End Stage ◽  
Positive Effect ◽  
Self Aggregation ◽  
Lateral Sclerosis ◽  
Liquid Liquid Phase Separation

Aggregates of TAR DNA-binding protein (TDP-43) are a hallmark of several neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). Although TDP-43 aggregates are an undisputed pathological species at the end stage of these diseases, the molecular changes underlying the initiation of aggregation are not fully understood. The aim of this study was to investigate how phase separation affects self-aggregation and aggregation seeded by pre-formed aggregates of either the low-complexity domain (LCD) or its short aggregation-promoting regions (APRs). By systematically varying the physicochemical conditions, we observed that liquid–liquid phase separation (LLPS) promotes spontaneous aggregation. However, we noticed less efficient seeded aggregation in phase separating conditions. By analyzing a broad range of conditions using the Hofmeister series of buffers, we confirmed that stabilizing hydrophobic interactions prevail over destabilizing electrostatic forces. RNA affected the cooperativity between LLPS and aggregation in a “reentrant” fashion, having the strongest positive effect at intermediate concentrations. Altogether, we conclude that conditions which favor LLPS enhance the subsequent aggregation of the TDP-43 LCD with complex dependence, but also negatively affect seeding kinetics.

scholarly journals Liquid-liquid phase separation of the chromosomal passenger complex drives parallel bundling of midzone microtubules

2022 ◽  
Author(s):  
Ewa Niedzialkowska ◽  
Tan M Truong ◽  
Luke A Eldredge ◽  
Stefanie Redemann ◽  
Denis Chretien ◽  
...  
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Chromosome Segregation ◽  
Dynamic Structure ◽  
Liquid Phase Separation ◽  
Chromosomal Passenger Complex ◽  
Chromosomal Passenger ◽  
Spindle Midzone ◽  
Liquid Liquid Phase Separation

The spindle midzone is a dynamic structure that forms during anaphase, mediates chromosome segregation, and provides a signaling platform to position the cleavage furrow. The spindle midzone comprises two antiparallel bundles of microtubules (MTs) but the process of their formation is poorly understood. Here, we show that the Chromosomal Passenger Complex (CPC) undergoes liquid-liquid phase separation (LLPS) to generate parallel MT bundles in vitro when incubated with free tubulin and GTP. MT bundles emerge from CPC droplets with protruding minus-ends that then grow into long, tapered MT structures. During this growth, the CPC in condensates apparently reorganize to coat and bundle the resulting MT structures. CPC mutants attenuated for LLPS or MT binding prevented the generation of parallel MT bundles in vitro and reduced the number of MTs present at spindle midzones in HeLa cells. Our data uncovers a kinase-independent function of the CPC and provides models for how cells generate parallel-bundled MT structures that are important for the assembly of the mitotic spindle.

scholarly journals Exploiting mammalian low-complexity domains for liquid-liquid phase separation–driven underwater adhesive coatings

2019 ◽  
Vol 5 (8) ◽  
pp. eaax3155 ◽  
Author(s):  
Mengkui Cui ◽  
Xinyu Wang ◽  
Bolin An ◽  
Chen Zhang ◽  
Xinrui Gui ◽  
...  
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Soft Materials ◽  
Low Complexity ◽  
Liquid Phase Separation ◽  
Biologically Inspired ◽  
Underwater Adhesion ◽  
Assembly Mechanism ◽  
Adhesion Performance ◽  
Liquid Liquid Phase Separation

Many biological materials form via liquid-liquid phase separation (LLPS), followed by maturation into a solid-like state. Here, using a biologically inspired assembly mechanism designed to recapitulate these sequential assemblies, we develop ultrastrong underwater adhesives made from engineered proteins containing mammalian low-complexity (LC) domains. We show that LC domain–mediated LLPS and maturation substantially promotes the wetting, adsorption, priming, and formation of dense, uniform amyloid nanofiber coatings on diverse surfaces (e.g., Teflon), and even penetrating difficult-to-access locations such as the interiors of microfluidic devices. Notably, these coatings can be deposited on substrates over a broad range of pH values (3 to 11) and salt concentrations (up to 1 M NaCl) and exhibit strong underwater adhesion performance. Beyond demonstrating the utility of mammalian LC domains for driving LLPS in soft materials applications, our study illustrates a powerful example of how combining LLPS with subsequent maturation steps can be harnessed for engineering protein-based materials.

scholarly journals Poly-glutamine-dependent self-association as a potential mechanism for regulation of androgen receptor activity

2021 ◽  
Author(s):  
Josep Rizo ◽  
Carlos M. Roggero ◽  
Victoria Esser ◽  
Lingling Duan ◽  
Allyson M. Rice ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Phase Separation ◽  
Androgen Receptor ◽  
Liquid Phase ◽  
Transcriptional Activity ◽  
Molecular Mechanisms ◽  
Catalytic Domain ◽  
Low Complexity ◽  
Liquid Phase Separation ◽  
Liquid Liquid Phase Separation

The androgen receptor (AR) plays a central role in prostate cancer. Development of castration resistant prostate cancer (CRPC) requires androgen-independent activation of AR, which involves its large N-terminal domain (NTD) and entails dramatic epigenetic changes depending in part on histone lysine demethylases (KDMs) that interact with AR. The AR-NTD is rich in low-complexity sequences, including a polyQ repeat. Longer polyQ sequences were reported to decrease transcriptional activity and to protect against prostate cancer. However, the molecular mechanisms underlying these observations are unclear. Using NMR spectroscopy, here we identify weak interactions between the AR-NTD and the KDM4A catalytic domain, and between the AR ligand-binding domain and a central KDM4A region that also contains low-complexity sequences. We also show that the AR-NTD can undergo liquid-liquid phase separation in vitro, with longer polyQ sequences phase separating more readily. Moreover, longer polyQ sequences hinder nuclear localization in the absence of hormone and increase the propensity for formation of AR-containing puncta in the nucleus of cells treated with dihydrotestosterone. These results lead us to hypothesize that polyQ-dependent liquid-liquid phase separation may provide a mechanism to decrease the transcriptional activity of AR, potentially opening new opportunities to design effective therapies against CRPC.

scholarly journals The Role of Methionine Residues in the Regulation of Liquid-Liquid Phase Separation

Biomolecules ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1248
Author(s):  
Juan Carlos Aledo
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Low Complexity ◽  
Liquid Phase Separation ◽  
Modular Architecture ◽  
Residue Interaction ◽  
Methionine Residues ◽  
Molecular Forces ◽  
Liquid Liquid Phase Separation

Membraneless organelles are non-stoichiometric supramolecular structures in the micron scale. These structures can be quickly assembled/disassembled in a regulated fashion in response to specific stimuli. Membraneless organelles contribute to the spatiotemporal compartmentalization of the cell, and they are involved in diverse cellular processes often, but not exclusively, related to RNA metabolism. Liquid-liquid phase separation, a reversible event involving demixing into two distinct liquid phases, provides a physical framework to gain insights concerning the molecular forces underlying the process and how they can be tuned according to the cellular needs. Proteins able to undergo phase separation usually present a modular architecture, which favors a multivalency-driven demixing. We discuss the role of low complexity regions in establishing networks of intra- and intermolecular interactions that collectively control the phase regime. Post-translational modifications of the residues present in these domains provide a convenient strategy to reshape the residue–residue interaction networks that determine the dynamics of phase separation. Focus will be placed on those proteins with low complexity domains exhibiting a biased composition towards the amino acid methionine and the prominent role that reversible methionine sulfoxidation plays in the assembly/disassembly of biomolecular condensates.

scholarly journals The C-terminal low-complexity domain involved in liquid–liquid phase separation is required for BRD4 function in vivo

2019 ◽  
Vol 11 (9) ◽  
pp. 807-809
Author(s):  
Chenlu Wang ◽  
Erhao Zhang ◽  
Fan Wu ◽  
Yufeng Sun ◽  
Yingcheng Wu ◽  
...  
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Low Complexity ◽  
Liquid Phase Separation ◽  
Liquid Liquid Phase Separation

scholarly journals Inhibition of amyloid formation of the Nucleoprotein of SARS-CoV-2

2021 ◽  
Author(s):  
Einav Tayeb-Fligelman ◽  
Xinyi Cheng ◽  
Christen Tai ◽  
Jeannette T. Bowler ◽  
Sarah Griner ◽  
...  
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Low Complexity ◽  
Fibril Formation ◽  
Liquid Phase Separation ◽  
Amyloid Formation ◽  
Rna Packaging ◽  
Atomic Structures ◽  
Amyloid Fibril Formation ◽  
Liquid Liquid Phase Separation

The SARS-CoV-2 Nucleoprotein (NCAP) functions in RNA packaging during viral replication and assembly. Computational analysis of its amino acid sequence reveals a central low-complexity domain (LCD) having sequence features akin to LCDs in other proteins known to function in liquid-liquid phase separation. Here we show that in the presence of viral RNA, NCAP, and also its LCD segment alone, form amyloid-like fibrils when undergoing liquid-liquid phase separation. Within the LCD we identified three 6-residue segments that drive amyloid fibril formation. We determined atomic structures for fibrils formed by each of the three identified segments. These structures informed our design of peptide inhibitors of NCAP fibril formation and liquid-liquid phase separation, suggesting a therapeutic route for Covid-19.

scholarly journals Molecular interactions underlying liquid−liquid phase separation of the FUS low-complexity domain

2019 ◽  
Vol 26 (7) ◽  
pp. 637-648 ◽  
Author(s):  
Anastasia C. Murthy ◽  
Gregory L. Dignon ◽  
Yelena Kan ◽  
Gül H. Zerze ◽  
Sapun H. Parekh ◽  
...  
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Molecular Interactions ◽  
Low Complexity ◽  
Liquid Phase Separation ◽  
Liquid Liquid Phase Separation
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