1
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Scott-Hewitt N, Mahoney M, Huang Y, Korte N, Yvanka de Soysa T, Wilton DK, Knorr E, Mastro K, Chang A, Zhang A, Melville D, Schenone M, Hartigan C, Stevens B. Microglial-derived C1q integrates into neuronal ribonucleoprotein complexes and impacts protein homeostasis in the aging brain. Cell 2024; 187:4193-4212.e24. [PMID: 38942014 DOI: 10.1016/j.cell.2024.05.058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 01/08/2024] [Accepted: 05/31/2024] [Indexed: 06/30/2024]
Abstract
Neuroimmune interactions mediate intercellular communication and underlie critical brain functions. Microglia, CNS-resident macrophages, modulate the brain through direct physical interactions and the secretion of molecules. One such secreted factor, the complement protein C1q, contributes to complement-mediated synapse elimination in both developmental and disease models, yet brain C1q protein levels increase significantly throughout aging. Here, we report that C1q interacts with neuronal ribonucleoprotein (RNP) complexes in an age-dependent manner. Purified C1q protein undergoes RNA-dependent liquid-liquid phase separation (LLPS) in vitro, and the interaction of C1q with neuronal RNP complexes in vivo is dependent on RNA and endocytosis. Mice lacking C1q have age-specific alterations in neuronal protein synthesis in vivo and impaired fear memory extinction. Together, our findings reveal a biophysical property of C1q that underlies RNA- and age-dependent neuronal interactions and demonstrate a role of C1q in critical intracellular neuronal processes.
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Affiliation(s)
- Nicole Scott-Hewitt
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; The Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
| | - Matthew Mahoney
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Youtong Huang
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; The Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Nils Korte
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; The Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - T Yvanka de Soysa
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; The Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Daniel K Wilton
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; The Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Emily Knorr
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Kevin Mastro
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; The Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Allison Chang
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Allison Zhang
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - David Melville
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Monica Schenone
- The Broad Proteomics Platform, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Christina Hartigan
- The Broad Proteomics Platform, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Beth Stevens
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; The Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Howard Hughes Medical Investigator, Boston Children's Hospital, Boston, MA 02115, USA.
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2
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Chattaraj A, Shakhnovich EI. Multi-condensate state as a functional strategy to optimize the cell signaling output. Nat Commun 2024; 15:6268. [PMID: 39054333 PMCID: PMC11272944 DOI: 10.1038/s41467-024-50489-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 07/10/2024] [Indexed: 07/27/2024] Open
Abstract
The existence of multiple biomolecular condensates inside living cells is a peculiar phenomenon not compatible with the predictions of equilibrium statistical mechanics. In this work, we address the problem of multiple condensates state (MCS) from a functional perspective. We combine Langevin dynamics, reaction-diffusion simulation, and dynamical systems theory to demonstrate that MCS can indeed be a function optimization strategy. Using Arp2/3 mediated actin nucleation pathway as an example, we show that actin polymerization is maximum at an optimal number of condensates. For a fixed amount of Arp2/3, MCS produces a greater response compared to its single condensate counterpart. Our analysis reveals the functional significance of the condensate size distribution which can be mapped to the recent experimental findings. Given the spatial heterogeneity within condensates and non-linear nature of intracellular networks, we envision MCS to be a generic functional solution, so that structures of network motifs may have evolved to accommodate such configurations.
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Affiliation(s)
- Aniruddha Chattaraj
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Eugene I Shakhnovich
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.
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3
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Kelley FM, Ani A, Pinlac EG, Linders B, Favetta B, Barai M, Ma Y, Singh A, Dignon GL, Gu Y, Schuster BS. Controlled and orthogonal partitioning of large particles into biomolecular condensates. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.11.603072. [PMID: 39071308 PMCID: PMC11275771 DOI: 10.1101/2024.07.11.603072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
Biomolecular condensates arising from liquid-liquid phase separation contribute to diverse cellular processes, such as gene expression. Partitioning of client molecules into condensates is critical to regulating the composition and function of condensates. Previous studies suggest that client size limits partitioning, with dextrans >5 nm excluded from condensates. Here, we asked whether larger particles, such as macromolecular complexes, can partition into condensates based on particle-condensate interactions. We sought to discover the biophysical principles that govern particle inclusion in or exclusion from condensates using polymer nanoparticles with tailored surface chemistries as models of macromolecular complexes. Particles coated with polyethylene glycol (PEG) did not partition into condensates. We next leveraged the PEGylated particles as an inert platform to which we conjugated specific adhesive moieties. Particles functionalized with biotin partitioned into condensates containing streptavidin, driven by high-affinity biotin-streptavidin binding. Oligonucleotide-decorated particles exhibited varying degrees of partitioning into condensates, depending on condensate composition. Partitioning of oligonucleotide-coated particles was tuned by altering salt concentration, oligonucleotide length, and oligonucleotide surface density. Remarkably, beads with distinct surface chemistries partitioned orthogonally into immiscible condensates. Based on our experiments, we conclude that arbitrarily large particles can controllably partition into biomolecular condensates given sufficiently strong condensate-particle interactions, a conclusion also supported by our coarse-grained molecular dynamics simulations and theory. These findings may provide insights into how various cellular processes are achieved based on partitioning of large clients into biomolecular condensates, as well as offer design principles for the development of drug delivery systems that selectively target disease-related biomolecular condensates.
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Affiliation(s)
- Fleurie M. Kelley
- Department of Chemical and Biochemical Engineering, Rutgers, the State University of New Jersey, Piscataway, NJ 08854
| | - Anas Ani
- Department of Chemical and Biochemical Engineering, Rutgers, the State University of New Jersey, Piscataway, NJ 08854
- Department of Chemistry and Chemical Biology, Rutgers, the State University of New Jersey, Piscataway, NJ 08854
| | - Emily G. Pinlac
- Department of Chemical and Biochemical Engineering, Rutgers, the State University of New Jersey, Piscataway, NJ 08854
| | - Bridget Linders
- Department of Chemical and Biochemical Engineering, Rutgers, the State University of New Jersey, Piscataway, NJ 08854
| | - Bruna Favetta
- Department of Biomedical Engineering, Rutgers, the State University of New Jersey, Piscataway, NJ 08854
| | - Mayur Barai
- Department of Chemical and Biochemical Engineering, Rutgers, the State University of New Jersey, Piscataway, NJ 08854
| | - Yuchen Ma
- Department of Chemistry and Chemical Biology, Rutgers, the State University of New Jersey, Piscataway, NJ 08854
| | - Arjun Singh
- Department of Chemical and Biochemical Engineering, Rutgers, the State University of New Jersey, Piscataway, NJ 08854
| | - Gregory L. Dignon
- Department of Chemical and Biochemical Engineering, Rutgers, the State University of New Jersey, Piscataway, NJ 08854
| | - Yuwei Gu
- Department of Chemistry and Chemical Biology, Rutgers, the State University of New Jersey, Piscataway, NJ 08854
| | - Benjamin S. Schuster
- Department of Chemical and Biochemical Engineering, Rutgers, the State University of New Jersey, Piscataway, NJ 08854
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4
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Zhou HX, Kota D, Qin S, Prasad R. Fundamental Aspects of Phase-Separated Biomolecular Condensates. Chem Rev 2024; 124:8550-8595. [PMID: 38885177 PMCID: PMC11260227 DOI: 10.1021/acs.chemrev.4c00138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
Biomolecular condensates, formed through phase separation, are upending our understanding in much of molecular, cell, and developmental biology. There is an urgent need to elucidate the physicochemical foundations of the behaviors and properties of biomolecular condensates. Here we aim to fill this need by writing a comprehensive, critical, and accessible review on the fundamental aspects of phase-separated biomolecular condensates. We introduce the relevant theoretical background, present the theoretical basis for the computation and experimental measurement of condensate properties, and give mechanistic interpretations of condensate behaviors and properties in terms of interactions at the molecular and residue levels.
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Affiliation(s)
- Huan-Xiang Zhou
- Department of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, USA
- Department of Physics, University of Illinois Chicago, Chicago, Illinois 60607, USA
| | - Divya Kota
- Department of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, USA
| | - Sanbo Qin
- Department of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, USA
| | - Ramesh Prasad
- Department of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, USA
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5
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Chattaraj A, Shakhnovich EI. Separation of sticker-spacer energetics governs the coalescence of metastable biomolecular condensates. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.03.560747. [PMID: 37873097 PMCID: PMC10592914 DOI: 10.1101/2023.10.03.560747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Biological condensates often emerge as a multi-droplet state and never coalesce into one large droplet within the experimental timespan. Previous work revealed that the sticker-spacer architecture of biopolymers may dynamically stabilize the multi-droplet state. Here, we simulate the condensate coalescence using metadynamics approach and reveal two distinct physical mechanisms underlying the fusion of droplets. Condensates made of sticker-spacer polymers readily undergo a kinetic arrest when stickers exhibit slow exchange while fast exchanging stickers at similar levels of saturation allow merger to equilibrium states. On the other hand, condensates composed of homopolymers fuse readily until they reach a threshold density. Increase in entropy upon inter-condensate mixing of chains drives the fusion of sticker-spacer chains. We map the range of mechanisms of kinetic arrest from slow sticker exchange dynamics to density mediated in terms of energetic separation of stickers and spacers. Our predictions appear to be in excellent agreement with recent experiments probing dynamic nature of protein-RNA condensates.
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Affiliation(s)
- Aniruddha Chattaraj
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Eugene I Shakhnovich
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
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6
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Holkar A, Gao S, Villaseñor K, Lake M, Srivastava S. Quantitative turbidimetric characterization of stabilized complex coacervate dispersions. SOFT MATTER 2024; 20:5060-5070. [PMID: 38743276 DOI: 10.1039/d3sm01761c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Stabilizing complex coacervate microdroplets is desirable due to their various applications, such as bioreactors, drug delivery vehicles, and encapsulants. Here, we present quantitative characterization of complex coacervate dispersion stability inferred by turbidimetry measurements. The stability of the dispersions is shown to be modulated by the concentrations of comb polyelectrolyte (cPE) stabilizers and salt. We demonstrate cPEs as effective stabilizers for complex coacervate dispersions independent of the chemistry or length of the constituent polyelectrolytes, salts, or preparation routes. By monitoring the temporal evolution of dispersion turbidity, we show that cPEs suppress microdroplet coalescence with minimal change in microdroplet sizes over 48 hours, even at salt concentrations up to 300 mM. The number density and average microdroplet size are shown to be controlled by varying the cPE and salt concentrations. Lastly, turbidity maps, akin to binodal phase maps, depict an expansion of the turbid two-phase region and an increase in the salt resistance of the coacervates upon the introduction of cPEs. The coacervate salt resistance is shown to increase by >3×, and this increase is maintained for up to 15 days, demonstrating that cPEs impart higher salt resistance over extended durations.
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Affiliation(s)
- Advait Holkar
- Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Shang Gao
- Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Kathleen Villaseñor
- Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Michael Lake
- NSF BioPACIFIC MIP, University of California, Los Angeles, Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Samanvaya Srivastava
- Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA.
- NSF BioPACIFIC MIP, University of California, Los Angeles, Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Institute for Carbon Management, University of California, Los Angeles, Los Angeles, CA 90095, USA
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7
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Scholl A, Liu Y, Seydoux G. Caenorhabditis elegans germ granules accumulate hundreds of low translation mRNAs with no systematic preference for germ cell fate regulators. Development 2024; 151:dev202575. [PMID: 38984542 PMCID: PMC11266749 DOI: 10.1242/dev.202575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Accepted: 06/04/2024] [Indexed: 07/11/2024]
Abstract
In animals with germ plasm, embryonic germline precursors inherit germ granules, condensates proposed to regulate mRNAs coding for germ cell fate determinants. In Caenorhabditis elegans, mRNAs are recruited to germ granules by MEG-3, a sequence non-specific RNA-binding protein that forms stabilizing interfacial clusters on germ granules. Using fluorescence in situ hybridization, we confirmed that 441 MEG-3-bound transcripts are distributed in a pattern consistent with enrichment in germ granules. Thirteen are related to transcripts reported in germ granules in Drosophila or Nasonia. The majority, however, are low-translation maternal transcripts required for embryogenesis that are not maintained preferentially in the nascent germline. Granule enrichment raises the concentration of certain transcripts in germ plasm but is not essential to regulate mRNA translation or stability. Our findings suggest that only a minority of germ granule-associated transcripts contribute to germ cell fate in C. elegans and that the vast majority function as non-specific scaffolds for MEG-3.
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Affiliation(s)
- Alyshia Scholl
- HHMI and Dept. of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Yihong Liu
- HHMI and Dept. of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Geraldine Seydoux
- HHMI and Dept. of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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8
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Latham AP, Zhu L, Sharon DA, Ye S, Willard AP, Zhang X, Zhang B. Microphase Separation Produces Interfacial Environment within Diblock Biomolecular Condensates. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.03.30.534967. [PMID: 37034777 PMCID: PMC10081284 DOI: 10.1101/2023.03.30.534967] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The phase separation of intrinsically disordered proteins is emerging as an important mechanism for cellular organization. However, efforts to connect protein sequences to the physical properties of condensates, i.e., the molecular grammar, are hampered by a lack of effective approaches for probing high-resolution structural details. Using a combination of multiscale simulations and fluorescence lifetime imaging microscopy experiments, we systematically explored a series of systems consisting of diblock elastin-like polypeptides (ELP). The simulations succeeded in reproducing the variation of condensate stability upon amino acid substitution and revealed different microenvironments within a single condensate, which we verified with environmentally sensitive fluorophores. The interspersion of hydrophilic and hydrophobic residues and a lack of secondary structure formation result in an interfacial environment, which explains both the strong correlation between ELP condensate stability and interfacial hydrophobicity scales, as well as the prevalence of protein-water hydrogen bonds. Our study uncovers new mechanisms for condensate stability and organization that may be broadly applicable.
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Affiliation(s)
- Andrew P Latham
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Longchen Zhu
- Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, 600 Dunyu Road, Hangzhou 310030, Zhejiang Province, China
- Westlake Laboratory of Life Sciences and Biomedicine, 18 Shilongshan Road, Hangzhou 310024, Zhejiang Province, China
| | - Dina A Sharon
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Songtao Ye
- Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, 600 Dunyu Road, Hangzhou 310030, Zhejiang Province, China
- Westlake Laboratory of Life Sciences and Biomedicine, 18 Shilongshan Road, Hangzhou 310024, Zhejiang Province, China
| | - Adam P Willard
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Xin Zhang
- Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, 600 Dunyu Road, Hangzhou 310030, Zhejiang Province, China
- Westlake Laboratory of Life Sciences and Biomedicine, 18 Shilongshan Road, Hangzhou 310024, Zhejiang Province, China
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
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9
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Pamula MC, Lehmann R. How germ granules promote germ cell fate. Nat Rev Genet 2024:10.1038/s41576-024-00744-8. [PMID: 38890558 DOI: 10.1038/s41576-024-00744-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/08/2024] [Indexed: 06/20/2024]
Abstract
Germ cells are the only cells in the body capable of giving rise to a new organism, and this totipotency hinges on their ability to assemble membraneless germ granules. These specialized RNA and protein complexes are hallmarks of germ cells throughout their life cycle: as embryonic germ granules in late oocytes and zygotes, Balbiani bodies in immature oocytes, and nuage in maturing gametes. Decades of developmental, genetic and biochemical studies have identified protein and RNA constituents unique to germ granules and have implicated these in germ cell identity, genome integrity and gamete differentiation. Now, emerging research is defining germ granules as biomolecular condensates that achieve high molecular concentrations by phase separation, and it is assigning distinct roles to germ granules during different stages of germline development. This organization of the germ cell cytoplasm into cellular subcompartments seems to be critical not only for the flawless continuity through the germline life cycle within the developing organism but also for the success of the next generation.
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Affiliation(s)
| | - Ruth Lehmann
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA.
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.
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10
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Chen F, Li X, Guo W, Wang Y, Guo M, Shum HC. Size Scaling of Condensates in Multicomponent Phase Separation. J Am Chem Soc 2024; 146:16000-16009. [PMID: 38809420 DOI: 10.1021/jacs.4c02906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
Constant proportionalities between cells and their intracellular organelles have been widely observed in various types of cells, known as intracellular size scaling. However, the mechanism underlying the size scaling and its modulation by environmental factors in multicomponent systems remain poorly understood. Here, we study the size scaling of membrane-less condensates using microdroplet-encapsulated minimalistic condensates formed by droplet microfluidics and mean-field theory. We demonstrate that the size scaling of condensates is an inherent characteristic of liquid-liquid phase separation. This concept is supported by experiments showing the occurrence of size scaling phenomena in various condensate systems and a generic lever rule acquired from mean-field theory. Moreover, it is found that the condensate-to-microdroplet scaling ratio can be affected by the solute and salt concentrations, with good agreement between experiments and predictions by theory. Notably, we identify a noise buffering mechanism whereby condensates composed of large macromolecules effectively maintain constant volumes and counteract concentration fluctuations of small molecules. This mechanism is achieved through the dynamic rearrangement of small molecules in and out of membrane-free interfaces. Our work provides crucial insights into understanding mechanistic principles that govern the size of cells and intracellular organelles as well as associated biological functions.
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Affiliation(s)
- Feipeng Chen
- Department of Mechanical Engineering, the University of Hong Kong, Pokfulam Road, Hong Kong (SAR) 999077, China
| | - Xiufeng Li
- Advanced Biomedical Instrumentation Centre, Hong Kong Science Park, Shatin, New Territories, Hong Kong (SAR) 999077, China
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, Jiangsu, China
| | - Wei Guo
- Department of Mechanical Engineering, the University of Hong Kong, Pokfulam Road, Hong Kong (SAR) 999077, China
- Advanced Biomedical Instrumentation Centre, Hong Kong Science Park, Shatin, New Territories, Hong Kong (SAR) 999077, China
| | - Yuchao Wang
- Department of Mechanical Engineering, the University of Hong Kong, Pokfulam Road, Hong Kong (SAR) 999077, China
| | - Ming Guo
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Ho Cheung Shum
- Department of Mechanical Engineering, the University of Hong Kong, Pokfulam Road, Hong Kong (SAR) 999077, China
- Advanced Biomedical Instrumentation Centre, Hong Kong Science Park, Shatin, New Territories, Hong Kong (SAR) 999077, China
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11
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Choi CH, Lee DSW, Sanders DW, Brangwynne CP. Condensate interfaces can accelerate protein aggregation. Biophys J 2024; 123:1404-1413. [PMID: 37837191 PMCID: PMC11163288 DOI: 10.1016/j.bpj.2023.10.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 09/16/2023] [Accepted: 10/10/2023] [Indexed: 10/15/2023] Open
Abstract
Protein aggregates, formed from the assembly of aberrant, misfolded proteins, are a hallmark of neurodegenerative diseases. Disease-associated aggregates such as mutant Huntingtin polyQ inclusions, are typically enriched in p62/SQSTM1, an oligomeric protein that binds to and sequesters aberrant proteins. p62 has been suggested to sequester proteins through formation of liquid-like biomolecular condensates, but the physical mechanisms by which p62 condensates may regulate pathological protein aggregation remain unclear. Here, we use a light-inducible biomimetic condensate system to show that p62 condensates enhance coarsening of mutant polyQ aggregates through interface-mediated sequestration, which accelerates polyQ accumulation into larger aggregates. However, the resulting large aggregates accumulate polyubiquitinated proteins, which depletes free p62, ultimately suppressing further p62 condensation. This dynamic interplay between interface-mediated coarsening of solid aggregates and downstream consequences on the phase behavior of associated regulatory proteins could contribute to the onset and progression of protein aggregation diseases.
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Affiliation(s)
- Chang-Hyun Choi
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey
| | - Daniel S W Lee
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey
| | - David W Sanders
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey
| | - Clifford P Brangwynne
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey; Omenn-Darling Bioengineering Institute, Princeton University, Princeton, New Jersey; Howard Hughes Medical Institute, Chevy Chase, Maryland.
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12
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Roggeveen JV, Wang H, Shi Z, Stone HA. A calibration-free model of micropipette aspiration for measuring properties of protein condensates. Biophys J 2024; 123:1393-1403. [PMID: 37789618 PMCID: PMC11163300 DOI: 10.1016/j.bpj.2023.09.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 08/13/2023] [Accepted: 09/27/2023] [Indexed: 10/05/2023] Open
Abstract
There is growing evidence that biological condensates, which are also referred to as membraneless organelles, and liquid-liquid phase separation play critical roles regulating many important cellular processes. Understanding the roles these condensates play in biology is predicated on understanding the material properties of these complex substances. Recently, micropipette aspiration (MPA) has been proposed as a tool to assay the viscosity and surface tension of condensates. This tool allows the measurement of both material properties in one relatively simple experiment, in contrast to many other techniques that only provide one or a ratio of parameters. While this technique has been commonly used in the literature to determine the material properties of membrane-bound objects dating back decades, the model describing the dynamics of MPA for objects with an external membrane does not correctly capture the hydrodynamics of unbounded fluids, leading to a calibration parameter several orders of magnitude larger than predicted. In this work we derive a new model for MPA of biological condensates that does not require any calibration and is consistent with the hydrodynamics of the MPA geometry. We validate the predictions of this model by conducting MPA experiments on a standard silicone oil of known material properties and are able to predict the viscosity and surface tension using MPA. Finally, we reanalyze with this new model the MPA data presented in previous works for condensates formed from LAF-1 RGG domains.
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Affiliation(s)
- James V Roggeveen
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey
| | - Huan Wang
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey
| | - Zheng Shi
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey.
| | - Howard A Stone
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey.
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13
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Ji Y, Qiao Y. Tuning interfacial fluidity and colloidal stability of membranized coacervate protocells. Commun Chem 2024; 7:122. [PMID: 38831043 PMCID: PMC11148010 DOI: 10.1038/s42004-024-01193-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Accepted: 04/29/2024] [Indexed: 06/05/2024] Open
Abstract
The cell membrane not only serves as the boundary between the cell's interior and the external environment but also plays a crucial role in regulating fundamental cellular behaviours. Interfacial membranization of membraneless coacervates, formed through liquid-liquid phase separation (LLPS), represents a reliable approach to constructing hierarchical cell-like entities known as protocells. In this study, we demonstrate the capability to modulate the interfacial membrane fluidity and thickness of dextran-bound coacervate protocells by adjusting the molecular weight of dextran or utilizing dextranase-catalyzed hydrolysis. This modulation allows for rational control over colloidal stability, interfacial molecular transport and cell-protocell interactions. Our work opens a new avenue for surface engineering of coacervate protocells, enabling the establishment of cell-mimicking structures and behaviours.
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Affiliation(s)
- Yanglimin Ji
- Beijing National Laboratory for Molecular Sciences (BNLMS), Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, 100190, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Yan Qiao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, 100190, Beijing, China.
- University of Chinese Academy of Sciences, 100049, Beijing, China.
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14
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Yan X, Kuster D, Mohanty P, Nijssen J, Pombo-García K, Rizuan A, Franzmann TM, Sergeeva A, Passos PM, George L, Wang SH, Shenoy J, Danielson HL, Honigmann A, Ayala YM, Fawzi NL, Mittal J, Alberti S, Hyman AA. Intra-condensate demixing of TDP-43 inside stress granules generates pathological aggregates. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.23.576837. [PMID: 38328053 PMCID: PMC10849624 DOI: 10.1101/2024.01.23.576837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Cytosolic aggregation of the nuclear protein TDP-43 is associated with many neurodegenerative diseases, but the triggers for TDP-43 aggregation are still debated. Here, we demonstrate that TDP-43 aggregation requires a double event. One is up-concentration in stress granules beyond a threshold, and the other is oxidative stress. These two events collectively induce intra-condensate demixing, giving rise to a dynamic TDP-43 enriched phase within stress granules, which subsequently transitions into pathological aggregates. Mechanistically, intra-condensate demixing is triggered by local unfolding of the RRM1 domain for intermolecular disulfide bond formation and by increased hydrophobic patch interactions in the C-terminal domain. By engineering TDP-43 variants resistant to intra-condensate demixing, we successfully eliminate pathological TDP-43 aggregates in cells. We conclude that up-concentration inside condensates and simultaneous exposure to environmental stress could be a general pathway for protein aggregation, with intra-condensate demixing constituting a key intermediate step.
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Affiliation(s)
- Xiao Yan
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG); Dresden, Saxony, 01307; Germany
| | - David Kuster
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG); Dresden, Saxony, 01307; Germany
- These authors contributed equally
| | - Priyesh Mohanty
- Artie McFerrin Department of Chemical Engineering, Texas A&M University; College Station, TX 77843; USA
- These authors contributed equally
| | - Jik Nijssen
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG); Dresden, Saxony, 01307; Germany
- These authors contributed equally
| | - Karina Pombo-García
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG); Dresden, Saxony, 01307; Germany
- These authors contributed equally
| | - Azamat Rizuan
- Artie McFerrin Department of Chemical Engineering, Texas A&M University; College Station, TX 77843; USA
| | - Titus M. Franzmann
- Biotechnology Center (BIOTEC), Center for Molecular and Cellular Bioengineering, Technische Universität Dresden; Dresden, Saxony, 01307; Germany
| | - Aleksandra Sergeeva
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG); Dresden, Saxony, 01307; Germany
- Biotechnology Center (BIOTEC), Center for Molecular and Cellular Bioengineering, Technische Universität Dresden; Dresden, Saxony, 01307; Germany
| | - Patricia M. Passos
- Edward Doisy Department of Biochemistry and Molecular Biology, Saint Louis University; St. Louis, MO 63104; USA
| | - Leah George
- Edward Doisy Department of Biochemistry and Molecular Biology, Saint Louis University; St. Louis, MO 63104; USA
| | - Szu-Huan Wang
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University; Providence, RI 02912; USA
| | - Jayakrishna Shenoy
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University; Providence, RI 02912; USA
| | - Helen L. Danielson
- Center for Biomedical Engineering, Brown University; Providence, RI 02912; USA
| | - Alf Honigmann
- Biotechnology Center (BIOTEC), Center for Molecular and Cellular Bioengineering, Technische Universität Dresden; Dresden, Saxony, 01307; Germany
| | - Yuna M. Ayala
- Edward Doisy Department of Biochemistry and Molecular Biology, Saint Louis University; St. Louis, MO 63104; USA
| | - Nicolas L. Fawzi
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University; Providence, RI 02912; USA
| | - Jeetain Mittal
- Artie McFerrin Department of Chemical Engineering, Texas A&M University; College Station, TX 77843; USA
- Department of Chemistry, Texas A&M University; College Station, TX 77843; USA
- Interdisciplinary Graduate Program in Genetics and Genomics, Texas A&M University; College Station, TX 77843; USA
| | - Simon Alberti
- Biotechnology Center (BIOTEC), Center for Molecular and Cellular Bioengineering, Technische Universität Dresden; Dresden, Saxony, 01307; Germany
| | - Anthony A. Hyman
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG); Dresden, Saxony, 01307; Germany
- Lead contact
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15
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Paul S, Arias MA, Wen L, Liao SE, Zhang J, Wang X, Regev O, Fei J. RNA molecules display distinctive organization at nuclear speckles. iScience 2024; 27:109603. [PMID: 38638569 PMCID: PMC11024929 DOI: 10.1016/j.isci.2024.109603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 01/05/2024] [Accepted: 03/25/2024] [Indexed: 04/20/2024] Open
Abstract
RNA molecules often play critical roles in assisting the formation of membraneless organelles in eukaryotic cells. Yet, little is known about the organization of RNAs within membraneless organelles. Here, using super-resolution imaging and nuclear speckles as a model system, we demonstrate that different sequence domains of RNA transcripts exhibit differential spatial distributions within speckles. Specifically, we image transcripts containing a region enriched in binding motifs of serine/arginine-rich (SR) proteins and another region enriched in binding motifs of heterogeneous nuclear ribonucleoproteins (hnRNPs). We show that these transcripts localize to the outer shell of speckles, with the SR motif-rich region localizing closer to the speckle center relative to the hnRNP motif-rich region. Further, we identify that this intra-speckle RNA organization is driven by the strength of RNA-protein interactions inside and outside speckles. Our results hint at novel functional roles of nuclear speckles and likely other membraneless organelles in organizing RNA substrates for biochemical reactions.
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Affiliation(s)
- Sneha Paul
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Mauricio A. Arias
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA
- Institute for System Genetics, NYU Langone Health, New York, NY 10016, USA
| | - Li Wen
- Department of Physics, The University of Chicago, Chicago, IL 60637, USA
| | - Susan E. Liao
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA
| | - Jiacheng Zhang
- Graduate Program in Biophysical Sciences, The University of Chicago, Chicago, IL 60637, USA
| | - Xiaoshu Wang
- The College, The University of Chicago, Chicago, IL 60637, USA
| | - Oded Regev
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA
| | - Jingyi Fei
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA
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16
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Zhen Zhou F, Swinkels PJM, Wei Yin S, Velikov KP, Schall P. Pickering stabilization mechanism revealed through direct imaging of particles with tuneable contact angle in a phase-separated binary solvent. J Colloid Interface Sci 2024; 662:471-478. [PMID: 38364472 DOI: 10.1016/j.jcis.2024.02.070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/18/2024] [Accepted: 02/06/2024] [Indexed: 02/18/2024]
Abstract
Pickering emulsions have attracted increasing attention from multiple fields, including food, cosmetics, healthcare, pharmaceutical, and agriculture. Their stability relies on the presence of colloidal particles instead of surfactant at the droplet interface, providing steric stabilization. Here, we demonstrate the microscopic attachment and detachment of particles with tunable contact angle at the interface underlying the Pickering emulsion stability. We vary the interfacial tension continuously by varying the temperature offset of a phase-separated binary liquid from its critical point, and employ confocal microscopy to directly observe the particles at the interface to determine their coverage and contact angle as a function of the varying interfacial tension. When the interfacial tension decreases upon approaching the binary liquid's critical point, the contact angle and detachment energy (ΔE) drop, and the particles move out of the interface. Microscopic imaging suggests necking and capillary interactions lead to clustering of the particles, before they eventually desorb from the interface. Macroscopic measurements show that concomitantly, coalescence takes place, and the emulsion loses its stability. These results reveal the interplay of interfacial energies, contact angle and surface coverage that underlies the Pickering emulsion stability, opening up ways to manipulate and design the stability through the microscopic behavior of the adsorbed particles.
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Affiliation(s)
- Fu Zhen Zhou
- College of Food Science, Fujian Agriculture and Forestry University, Fuzhou, PR China; Institute of Physics, University of Amsterdam, Amsterdam, The Netherlands; Research and Development Center of Food Proteins, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, Department of Food Science and Technology, South China University of Technology, Guangzhou, 51640, PR China
| | - Piet J M Swinkels
- Institute of Physics, University of Amsterdam, Amsterdam, The Netherlands
| | - Shou Wei Yin
- Research and Development Center of Food Proteins, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, Department of Food Science and Technology, South China University of Technology, Guangzhou, 51640, PR China; Sino-Singapore International Joint Research Institute, Guangzhou 510640, PR China
| | - Krassimir P Velikov
- Institute of Physics, University of Amsterdam, Amsterdam, The Netherlands; Unilever Innovation Centre Wageningen, Bronland 14, 6708 WH, Wageningen, The Netherlands; Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC, Utrecht, The Netherlands
| | - Peter Schall
- Institute of Physics, University of Amsterdam, Amsterdam, The Netherlands
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17
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Chattaraj A, Shakhnovich EI. Multi-condensate state as a functional strategy to optimize the cell signaling output. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.14.575571. [PMID: 38798333 PMCID: PMC11118381 DOI: 10.1101/2024.01.14.575571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
The existence of multiple biomolecular condensates inside living cells is a peculiar phenomenon not compatible with the predictions of equilibrium statistical mechanics. In this work, we address the problem of multiple condensates state (MCS) from a functional perspective. We combined Langevin dynamics, reaction-diffusion simulation, and dynamical systems theory to demonstrate that MCS can indeed be a function optimization strategy. Using Arp2/3 mediated actin nucleation pathway as an example, we show that actin polymerization is maximum at an optimal number of condensates. For a fixed amount of Arp2/3, MCS produces a greater response compared to its single condensate counterpart. Our analysis reveals the functional significance of the condensate size distribution which can be mapped to the recent experimental findings. Given the spatial heterogeneity within condensates and non-linear nature of intracellular networks, we envision MCS to be a generic functional solution, so that structures of network motifs may have evolved to accommodate such configurations.
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Affiliation(s)
- Aniruddha Chattaraj
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Eugene I Shakhnovich
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
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18
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Banerjee DS, Chigumira T, Lackner RM, Kratz JC, Chenoweth DM, Banerjee S, Zhang H. Interplay of condensate material properties and chromatin heterogeneity governs nuclear condensate ripening. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.07.593010. [PMID: 38766065 PMCID: PMC11100695 DOI: 10.1101/2024.05.07.593010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Biomolecular condensates play pivotal roles in many cellular processes, yet predicting condensate growth dynamics within the complex intracellular environment is challenging. While chromatin mechanics are known to influence condensate coarsening in the nucleus, the effect of condensate properties remains unclear. Our study demonstrates that the interplay between condensate properties and chromatin mechanics dictates condensate growth dynamics. Through chemical dimerization, we induced condensates of various properties in the cell nuclei, revealing distinct growth mechanisms: diffusion-driven or ripening-dominated. To explain experimental observations, we developed a quantitative theory that uncovers the role of chromatin in modulating condensate growth via size-dependent pressure. We find that surface tension is a critical factor in determining whether condensates undergo elastic or Ostwald ripening. Our model predicts that different condensates are affected differently by chromatin heterogeneity, validated by experimentally perturbing chromatin organization. Taken together, our work elucidates how condensate surface tension and chromatin heterogeneity govern nuclear condensate ripening.
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Affiliation(s)
- Deb Sankar Banerjee
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Present address: James Franck Institute, University of Chicago, Chicago, IL 60637, USA
| | - Tafadzwa Chigumira
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Rachel M Lackner
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
| | - Josiah C Kratz
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Present address: Computational Biology Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - David M Chenoweth
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
| | - Shiladitya Banerjee
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Huaiying Zhang
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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19
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Bressloff PC. Asymptotic analysis of particle cluster formation in the presence of anchoring sites. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2024; 47:30. [PMID: 38720027 PMCID: PMC11078859 DOI: 10.1140/epje/s10189-024-00425-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 04/15/2024] [Indexed: 05/12/2024]
Abstract
The aggregation or clustering of proteins and other macromolecules plays an important role in the formation of large-scale molecular assemblies within cell membranes. Examples of such assemblies include lipid rafts, and postsynaptic domains (PSDs) at excitatory and inhibitory synapses in neurons. PSDs are rich in scaffolding proteins that can transiently trap transmembrane neurotransmitter receptors, thus localizing them at specific spatial positions. Hence, PSDs play a key role in determining the strength of synaptic connections and their regulation during learning and memory. Recently, a two-dimensional (2D) diffusion-mediated aggregation model of PSD formation has been developed in which the spatial locations of the clusters are determined by a set of fixed anchoring sites. The system is kept out of equilibrium by the recycling of particles between the cell membrane and interior. This results in a stationary distribution consisting of multiple clusters, whose average size can be determined using an effective mean-field description of the particle concentration around each anchored cluster. In this paper, we derive corrections to the mean-field approximation by applying the theory of diffusion in singularly perturbed domains. The latter is a powerful analytical method for solving two-dimensional (2D) and three-dimensional (3D) diffusion problems in domains where small holes or perforations have been removed from the interior. Applications range from modeling intracellular diffusion, where interior holes could represent subcellular structures such as organelles or biological condensates, to tracking the spread of chemical pollutants or heat from localized sources. In this paper, we take the bounded domain to be the cell membrane and the holes to represent anchored clusters. The analysis proceeds by partitioning the membrane into a set of inner regions around each cluster, and an outer region where mean-field interactions occur. Asymptotically matching the inner and outer stationary solutions generates an asymptotic expansion of the particle concentration, which includes higher-order corrections to mean-field theory that depend on the positions of the clusters and the boundary of the domain. Motivated by a recent study of light-activated protein oligomerization in cells, we also develop the analogous theory for cluster formation in a three-dimensional (3D) domain. The details of the asymptotic analysis differ from the 2D case due to the contrasting singularity structure of 2D and 3D Green's functions.
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Affiliation(s)
- Paul C Bressloff
- Department of Mathematics, Imperial College London, London, SW7 2AZ, UK.
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20
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van Haren MHI, Visser BS, Spruijt E. Probing the surface charge of condensates using microelectrophoresis. Nat Commun 2024; 15:3564. [PMID: 38670952 PMCID: PMC11053090 DOI: 10.1038/s41467-024-47885-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Accepted: 04/16/2024] [Indexed: 04/28/2024] Open
Abstract
Biomolecular condensates play an important role in cellular organization. Coacervates are commonly used models that mimic the physicochemical properties of biomolecular condensates. The surface of condensates plays a key role in governing molecular exchange between condensates, accumulation of species at the interface, and the stability of condensates against coalescence. However, most important surface properties, including the surface charge and zeta potential, remain poorly characterized and understood. The zeta potential of coacervates is often measured using laser doppler electrophoresis, which assumes a size-independent electrophoretic mobility. Here, we show that this assumption is incorrect for liquid-like condensates and present an alternative method to study the electrophoretic mobility of coacervates and in vitro condensate models by microelectrophoresis and single-particle tracking. Coacervates have a size-dependent electrophoretic mobility, originating from their fluid nature, from which a well-defined zeta potential is calculated. Interestingly, microelectrophoresis measurements reveal that polylysine chains are enriched at the surface of polylysine/polyaspartic acid complex coacervates, which causes the negatively charged protein ɑ-synuclein to adsorb and accumulate at the interface. Addition of ATP inverts the surface charge, displaces ɑ-synuclein from the surface and may help to suppress its interface-catalyzed aggregation. Together, these findings show how condensate surface charge can be measured and altered, making this microelectrophoresis platform combined with automated single-particle tracking a promising characterization technique for both biomolecular condensates and coacervate protocells.
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Affiliation(s)
- Merlijn H I van Haren
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6523, AJ, Nijmegen, The Netherlands
| | - Brent S Visser
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6523, AJ, Nijmegen, The Netherlands
| | - Evan Spruijt
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6523, AJ, Nijmegen, The Netherlands.
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21
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Meier SM, Steinmetz MO, Barral Y. Microtubule specialization by +TIP networks: from mechanisms to functional implications. Trends Biochem Sci 2024; 49:318-332. [PMID: 38350804 DOI: 10.1016/j.tibs.2024.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 12/23/2023] [Accepted: 01/12/2024] [Indexed: 02/15/2024]
Abstract
To fulfill their actual cellular role, individual microtubules become functionally specialized through a broad range of mechanisms. The 'search and capture' model posits that microtubule dynamics and functions are specified by cellular targets that they capture (i.e., a posteriori), independently of the microtubule-organizing center (MTOC) they emerge from. However, work in budding yeast indicates that MTOCs may impart a functional identity to the microtubules they nucleate, a priori. Key effectors in this process are microtubule plus-end tracking proteins (+TIPs), which track microtubule tips to regulate their dynamics and facilitate their targeted interactions. In this review, we discuss potential mechanisms of a priori microtubule specialization, focusing on recent findings indicating that +TIP networks may undergo liquid biomolecular condensation in different cell types.
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Affiliation(s)
- Sandro M Meier
- Institute of Biochemistry, Department of Biology, and Bringing Materials to Life Initiative, ETH Zürich, Switzerland; Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen, Switzerland; Bringing Materials to Life Initiative, ETH Zürich, Switzerland
| | - Michel O Steinmetz
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen, Switzerland; University of Basel, Biozentrum, CH-4056 Basel, Switzerland.
| | - Yves Barral
- Institute of Biochemistry, Department of Biology, and Bringing Materials to Life Initiative, ETH Zürich, Switzerland; Bringing Materials to Life Initiative, ETH Zürich, Switzerland.
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22
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Abeysinghe AADT, Young EJ, Rowland AT, Dunshee LC, Urandur S, Sullivan MO, Kerfeld CA, Keating CD. Interfacial Assembly of Bacterial Microcompartment Shell Proteins in Aqueous Multiphase Systems. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2308390. [PMID: 38037673 DOI: 10.1002/smll.202308390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 11/13/2023] [Indexed: 12/02/2023]
Abstract
Compartments are a fundamental feature of life, based variously on lipid membranes, protein shells, or biopolymer phase separation. Here, this combines self-assembling bacterial microcompartment (BMC) shell proteins and liquid-liquid phase separation (LLPS) to develop new forms of compartmentalization. It is found that BMC shell proteins assemble at the liquid-liquid interfaces between either 1) the dextran-rich droplets and PEG-rich continuous phase of a poly(ethyleneglycol)(PEG)/dextran aqueous two-phase system, or 2) the polypeptide-rich coacervate droplets and continuous dilute phase of a polylysine/polyaspartate complex coacervate system. Interfacial protein assemblies in the coacervate system are sensitive to the ratio of cationic to anionic polypeptides, consistent with electrostatically-driven assembly. In both systems, interfacial protein assembly competes with aggregation, with protein concentration and polycation availability impacting coating. These two LLPS systems are then combined to form a three-phase system wherein coacervate droplets are contained within dextran-rich phase droplets. Interfacial localization of BMC hexameric shell proteins is tunable in a three-phase system by changing the polyelectrolyte charge ratio. The tens-of-micron scale BMC shell protein-coated droplets introduced here can accommodate bioactive cargo such as enzymes or RNA and represent a new synthetic cell strategy for organizing biomimetic functionality.
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Affiliation(s)
| | - Eric J Young
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA
| | - Andrew T Rowland
- Department of Chemistry, Pennsylvania State University, State College, PA, 16801, USA
| | - Lucas C Dunshee
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, 19716, USA
- Department of Biomedical Engineering, University of Delaware, Newark, DE, 19716, USA
| | - Sandeep Urandur
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, 19716, USA
- Department of Biomedical Engineering, University of Delaware, Newark, DE, 19716, USA
| | - Millicent O Sullivan
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, 19716, USA
- Department of Biomedical Engineering, University of Delaware, Newark, DE, 19716, USA
| | - Cheryl A Kerfeld
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
| | - Christine D Keating
- Department of Chemistry, Pennsylvania State University, State College, PA, 16801, USA
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23
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Wahiduzzaman, Tindell SJ, Alexander E, Hackney E, Kharel K, Schmidtke R, Arkov AL. Drosophila germ granules are assembled from protein components through different modes of competing interactions with the multi-domain Tudor protein. FEBS Lett 2024; 598:774-786. [PMID: 38499396 DOI: 10.1002/1873-3468.14846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 12/21/2023] [Accepted: 02/14/2024] [Indexed: 03/20/2024]
Abstract
Membraneless organelles are RNA-protein assemblies which have been implicated in post-transcriptional control. Germ cells form membraneless organelles referred to as germ granules, which contain conserved proteins including Tudor domain-containing scaffold polypeptides and their partner proteins that interact with Tudor domains. Here, we show that in Drosophila, different germ granule proteins associate with the multi-domain Tudor protein using different numbers of Tudor domains. Furthermore, these proteins compete for interaction with Tudor in vitro and, surprisingly, partition to distinct and poorly overlapping clusters in germ granules in vivo. This partition results in minimization of the competition. Our data suggest that Tudor forms structurally different configurations with different partner proteins which dictate different biophysical properties and phase separation parameters within the same granule.
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Affiliation(s)
- Wahiduzzaman
- Department of Biological Sciences, Murray State University, KY, USA
| | - Samuel J Tindell
- Department of Biological Sciences, Murray State University, KY, USA
| | - Emma Alexander
- Department of Biological Sciences, Murray State University, KY, USA
| | - Ethan Hackney
- Department of Biological Sciences, Murray State University, KY, USA
| | - Kabita Kharel
- Department of Biological Sciences, Murray State University, KY, USA
| | - Ryan Schmidtke
- Department of Biological Sciences, Murray State University, KY, USA
| | - Alexey L Arkov
- Department of Biological Sciences, Murray State University, KY, USA
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24
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Ye S, Latham AP, Tang Y, Hsiung CH, Chen J, Luo F, Liu Y, Zhang B, Zhang X. Micropolarity governs the structural organization of biomolecular condensates. Nat Chem Biol 2024; 20:443-451. [PMID: 37973891 PMCID: PMC10978266 DOI: 10.1038/s41589-023-01477-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 10/11/2023] [Indexed: 11/19/2023]
Abstract
Membraneless organelles within cells have unique microenvironments that play a critical role in their functions. However, how microenvironments of biomolecular condensates affect their structure and function remains unknown. In this study, we investigated the micropolarity and microviscosity of model biomolecular condensates by fluorescence lifetime imaging coupling with environmentally sensitive fluorophores. Using both in vitro and in cellulo systems, we demonstrated that sufficient micropolarity difference is key to forming multilayered condensates, where the shells present more polar microenvironments than the cores. Furthermore, micropolarity changes were shown to be accompanied by conversions of the layered structures. Decreased micropolarities of the granular components, accompanied by the increased micropolarities of the dense fibrillar components, result in the relocation of different nucleolus subcompartments in transcription-stalled conditions. Our results demonstrate the central role of the previously overlooked micropolarity in the regulation of structures and functions of membraneless organelles.
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Affiliation(s)
- Songtao Ye
- Department of Chemistry, Research Center for Industries of the Future, Westlake University, Hangzhou, China
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, China
| | - Andrew P Latham
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Yuqi Tang
- Department of Chemistry, Research Center for Industries of the Future, Westlake University, Hangzhou, China
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, China
| | - Chia-Heng Hsiung
- Department of Chemistry, Research Center for Industries of the Future, Westlake University, Hangzhou, China
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, China
| | - Junlin Chen
- Department of Chemistry, Research Center for Industries of the Future, Westlake University, Hangzhou, China
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, China
| | - Feng Luo
- Department of Chemistry, Research Center for Industries of the Future, Westlake University, Hangzhou, China
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, China
| | - Yu Liu
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Xin Zhang
- Department of Chemistry, Research Center for Industries of the Future, Westlake University, Hangzhou, China.
- Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou, China.
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, China.
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25
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Gama AR, Miller T, Venkatesan S, Lange JJ, Wu J, Song X, Bradford D, Unruh JR, Halfmann R. Protein supersaturation powers innate immune signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.03.20.533581. [PMID: 36993308 PMCID: PMC10055258 DOI: 10.1101/2023.03.20.533581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Innate immunity protects us in youth but turns against us as we age. The reason for this tradeoff is unclear. Seeking a thermodynamic basis, we focused on death fold domains (DFDs), whose ordered polymerization has been stoichiometrically linked to innate immune signal amplification. We hypothesized that soluble ensembles of DFDs function as phase change batteries that store energy via supersaturation and subsequently release it through nucleated polymerization. Using imaging and FRET-based cytometry to characterize the phase behaviors of all 109 human DFDs, we found that the hubs of innate immune signaling networks encode large nucleation barriers that are intrinsically insulated from cross-pathway activation. We showed via optogenetics that supersaturation drives signal amplification and that the inflammasome is constitutively supersaturated in vivo. Our findings reveal that the soluble "inactive" states of adaptor DFDs function as essential, yet impermanent, kinetic barriers to inflammatory cell death, suggesting a thermodynamic driving force for aging.
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Affiliation(s)
| | - Tayla Miller
- Stowers Institute for Medical Research, Kansas City, MO
| | | | | | - Jianzheng Wu
- Stowers Institute for Medical Research, Kansas City, MO
| | - Xiaoqing Song
- Stowers Institute for Medical Research, Kansas City, MO
| | - Dan Bradford
- Stowers Institute for Medical Research, Kansas City, MO
| | - Jay R Unruh
- Stowers Institute for Medical Research, Kansas City, MO
| | - Randal Halfmann
- Stowers Institute for Medical Research, Kansas City, MO
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, USA
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26
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Danlasky BM, Martinez M, Cassani M, Bodas D, Putnam A, Seydoux G. The P granule antibody KT3 recognizes epitopes in both PGL-1 and PGL-3. MICROPUBLICATION BIOLOGY 2024; 2024:10.17912/micropub.biology.001137. [PMID: 38440332 PMCID: PMC10910292 DOI: 10.17912/micropub.biology.001137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 02/09/2024] [Accepted: 02/13/2024] [Indexed: 03/06/2024]
Abstract
The KT3 antibody is a commercially available antibody that recognizes the P granule protein PGL-3 (Takeda et al., 2008). Using immunostaining and western blotting of purified peptide fragments, we show that KT3 recognizes both PGL-3 and its paralog PGL-1 , likely through a shared epitope in the intrinsically disordered region.
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Affiliation(s)
- Brennan M Danlasky
- Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine
| | - Mario Martinez
- Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine
| | - Madeline Cassani
- Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine
| | - Devavrat Bodas
- Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine
| | - Andrea Putnam
- Molecular Biology and Genetics, University of Wisconsin–Madison, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine
| | - Geraldine Seydoux
- Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine
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27
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Hoffmann C, Milovanovic D. Dipping contacts - a novel type of contact site at the interface between membraneless organelles and membranes. J Cell Sci 2023; 136:jcs261413. [PMID: 38149872 PMCID: PMC10785658 DOI: 10.1242/jcs.261413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2023] Open
Abstract
Liquid-liquid phase separation is a major mechanism for organizing macromolecules, particularly proteins with intrinsically disordered regions, in compartments not limited by a membrane or a scaffold. The cell can therefore be perceived as a complex emulsion containing many of these membraneless organelles, also referred to as biomolecular condensates, together with numerous membrane-bound organelles. It is currently unclear how such a complex concoction operates to allow for intracellular trafficking, signaling and metabolic processes to occur with high spatiotemporal precision. Based on experimental observations of synaptic vesicle condensates - a membraneless organelle that is in fact packed with membranes - we present here the framework of dipping contacts: a novel type of contact site between membraneless organelles and membranes. In this Hypothesis, we propose that our framework of dipping contacts can serve as a foundation to investigate the interface that couples the diffusion and material properties of condensates to biochemical processes occurring in membranes. The identity and regulation of this interface is especially critical in the case of neurodegenerative diseases, where aberrant inclusions of misfolded proteins and damaged organelles underlie cellular pathology.
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Affiliation(s)
- Christian Hoffmann
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543, USA
| | - Dragomir Milovanovic
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
- Whitman Center, Marine Biological Laboratory, Woods Hole, MA 02543, USA
- National Center for X-ray Tomography, Advanced Light Source, Berkeley, CA 94720, USA
- Einstein Center for Neuroscience, Charité-Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität Berlin and Berlin Institute of Health, 10117 Berlin, Germany
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28
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Dhakal S, Mondal M, Mirzazadeh A, Banerjee S, Ghosh A, Rangachari V. α-Synuclein emulsifies TDP-43 prion-like domain-RNA liquid droplets to promote heterotypic amyloid fibrils. Commun Biol 2023; 6:1227. [PMID: 38052886 PMCID: PMC10697960 DOI: 10.1038/s42003-023-05608-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 11/17/2023] [Indexed: 12/07/2023] Open
Abstract
Many neurodegenerative diseases including frontotemporal lobar degeneration (FTLD), Lewy body disease (LBD), multiple system atrophy (MSA), etc., show colocalized deposits of TDP-43 and α-synuclein (αS) aggregates. To understand whether these colocalizations are driven by specific molecular interactions between the two proteins, we previously showed that the prion-like C-terminal domain of TDP-43 (TDP-43PrLD) and αS synergistically interact to form neurotoxic heterotypic amyloids in homogeneous buffer conditions. However, it remains unclear if αS can modulate TDP-43 present within liquid droplets and biomolecular condensates called stress granules (SGs). Here, using cell culture and in vitro TDP-43PrLD - RNA liquid droplets as models along with microscopy, nanoscale AFM-IR spectroscopy, and biophysical analyses, we uncover the interactions of αS with phase-separated droplets. We learn that αS acts as a Pickering agent by forming clusters on the surface of TDP-43PrLD - RNA droplets. The aggregates of αS on these clusters emulsify the droplets by nucleating the formation of heterotypic TDP-43PrLD amyloid fibrils, structures of which are distinct from those derived from homogenous solutions. Together, these results reveal an intriguing property of αS to act as a Pickering agent while interacting with SGs and unmask the hitherto unknown role of αS in modulating TDP-43 proteinopathies.
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Affiliation(s)
- Shailendra Dhakal
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
- Center for Molecular and Cellular Biosciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Malay Mondal
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
- Center for Molecular and Cellular Biosciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Azin Mirzazadeh
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
- Center for Molecular and Cellular Biosciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Siddhartha Banerjee
- Department of Chemistry and Biochemistry, University of Alabama, Tuscaloosa, AL, 35401, USA
| | - Ayanjeet Ghosh
- Department of Chemistry and Biochemistry, University of Alabama, Tuscaloosa, AL, 35401, USA
| | - Vijayaraghavan Rangachari
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA.
- Center for Molecular and Cellular Biosciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA.
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29
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Lu T, Javed S, Bonfio C, Spruijt E. Interfacing Coacervates with Membranes: From Artificial Organelles and Hybrid Protocells to Intracellular Delivery. SMALL METHODS 2023; 7:e2300294. [PMID: 37354057 DOI: 10.1002/smtd.202300294] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/30/2023] [Indexed: 06/26/2023]
Abstract
Compartmentalization is crucial for the functioning of cells. Membranes enclose and protect the cell, regulate the transport of molecules entering and exiting the cell, and organize cellular machinery in subcompartments. In addition, membraneless condensates, or coacervates, offer dynamic compartments that act as biomolecular storage centers, organizational hubs, or reaction crucibles. Emerging evidence shows that phase-separated membraneless bodies in the cell are involved in a wide range of functional interactions with cellular membranes, leading to transmembrane signaling, membrane remodeling, intracellular transport, and vesicle formation. Such functional and dynamic interplay between phase-separated droplets and membranes also offers many potential benefits to artificial cells, as shown by recent studies involving coacervates and liposomes. Depending on the relative sizes and interaction strength between coacervates and membranes, coacervates can serve as artificial membraneless organelles inside liposomes, as templates for membrane assembly and hybrid artificial cell formation, as membrane remodelers for tubulation and possibly division, and finally, as cargo containers for transport and delivery of biomolecules across membranes by endocytosis or direct membrane crossing. Here, recent experimental examples of each of these functions are reviewed and the underlying physicochemical principles and possible future applications are discussed.
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Affiliation(s)
- Tiemei Lu
- Institute for Molecules and Materials, Radboud University, Nijmegen, 6525 AJ, The Netherlands
| | - Sadaf Javed
- Institute for Molecules and Materials, Radboud University, Nijmegen, 6525 AJ, The Netherlands
| | - Claudia Bonfio
- Institut de Science et d'Ingénierie Supramoléculaires (ISIS), CNRS UMR 7006, Université de Strasbourg, Strasbourg, 67083, France
| | - Evan Spruijt
- Institute for Molecules and Materials, Radboud University, Nijmegen, 6525 AJ, The Netherlands
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30
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Holland J, Castrejón-Pita AA, Tuinier R, Aarts DGAL, Nott TJ. Surface tension measurement and calculation of model biomolecular condensates. SOFT MATTER 2023; 19:8706-8716. [PMID: 37791635 PMCID: PMC10663989 DOI: 10.1039/d3sm00820g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 09/20/2023] [Indexed: 10/05/2023]
Abstract
The surface tension of liquid-like protein-rich biomolecular condensates is an emerging physical principle governing the mesoscopic interior organisation of biological cells. In this study, we present a method to evaluate the surface tension of model biomolecular condensates, through straighforward sessile drop measurements of capillary lengths and condensate densities. Our approach bypasses the need for characterizing condensate viscosities, which was required in previously reported techniques. We demonstrate this method using model condensates comprising two mutants of the intrinsically disordered protein Ddx4N. Notably, we uncover a detrimental impact of increased protein net charge on the surface tension of Ddx4N condensates. Furthermore, we explore the application of Scheutjens-Fleer theory, calculating condensate surface tensions through a self-consistent mean-field framework using Flory-Huggins interaction parameters. This relatively simple theory provides semi-quantitative accuracy in predicting Ddx4N condensate surface tensions and enables the evaluation of molecular organisation at condensate surfaces. Our findings shed light on the molecular details of fluid-fluid interfaces in biomolecular condensates.
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Affiliation(s)
- Jack Holland
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK.
- Dept. of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK.
| | | | - Remco Tuinier
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry & Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Dirk G A L Aarts
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UK.
| | - Timothy J Nott
- Dept. of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK.
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31
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Wang J, Abbas M, Huang Y, Wang J, Li Y. Redox-responsive peptide-based complex coacervates as delivery vehicles with controlled release of proteinous drugs. Commun Chem 2023; 6:243. [PMID: 37935871 PMCID: PMC10630460 DOI: 10.1038/s42004-023-01044-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 10/26/2023] [Indexed: 11/09/2023] Open
Abstract
Proteinous drugs are highly promising therapeutics to treat various diseases. However, they suffer from limited circulation times and severe off-target side effects. Inspired by active membraneless organelles capable of dynamic recruitment and releasing of specific proteins, here, we present the design of coacervates as therapeutic protocells, made from small metabolites (anionic molecules) and simple arginine-rich peptides (cationic motif) through liquid-liquid phase separation. These complex coacervates demonstrate that their assembly and disassembly can be regulated by redox chemistry, which helps to control the release of the therapeutic protein. A model proteinous drugs, tissue plasminogen activator (tPA), can rapidly compartmentalize inside the complex coacervates, and the coacervates formed from peptides conjugated with arginine-glycine-aspartic acid (RGD) motif (a fibrinogen-derived peptide sequence), show selective binding to the thrombus site and thus enhance on-target efficacy of tPA. Furthermore, the burst release of tPA can be controlled by the redox-induced dissolution of the coacervates. Our proof-of-principle complex coacervate system provides insights into the sequestration and release of proteinous drugs from advanced drug delivery systems and represents a step toward the construction of synthetic therapeutic protocells for biomedical applications.
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Affiliation(s)
- Jiahua Wang
- Department of Radiology, Shanghai Jiao Tong University School of Medicine Affiliated Sixth People's Hospital, Shanghai, 200233, China.
| | - Manzar Abbas
- Department of Chemistry, Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi, UAE
- Advanced Materials Chemistry Center (AMCC), Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi, UAE
| | - Yu Huang
- Department of Radiology, Shanghai Jiao Tong University School of Medicine Affiliated Sixth People's Hospital, Shanghai, 200233, China.
| | - Junyou Wang
- State Key Laboratory of Chemical Engineering and Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Yuehua Li
- Department of Radiology, Shanghai Jiao Tong University School of Medicine Affiliated Sixth People's Hospital, Shanghai, 200233, China.
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32
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Yamamoto T, Yamazaki T, Ninomiya K, Hirose T. Nascent ribosomal RNA act as surfactant that suppresses growth of fibrillar centers in nucleolus. Commun Biol 2023; 6:1129. [PMID: 37935838 PMCID: PMC10630424 DOI: 10.1038/s42003-023-05519-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 10/27/2023] [Indexed: 11/09/2023] Open
Abstract
Liquid-liquid phase separation (LLPS) has been thought to be the biophysical principle governing the assembly of the multiphase structures of nucleoli, the site of ribosomal biogenesis. Condensates assembled through LLPS increase their sizes to minimize the surface energy as far as their components are available. However, multiple microphases, fibrillar centers (FCs), dispersed in a nucleolus are stable and their sizes do not grow unless the transcription of pre-ribosomal RNA (pre-rRNA) is inhibited. To understand the mechanism of the suppression of the FC growth, we here construct a minimal theoretical model by taking into account nascent pre-rRNAs tethered to FC surfaces by RNA polymerase I. The prediction of this theory was supported by our experiments that quantitatively measure the dependence of the size of FCs on the transcription level. This work sheds light on the role of nascent RNAs in controlling the size of nuclear bodies.
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Affiliation(s)
- Tetsuya Yamamoto
- Institute for Chemical Reaction Design and Discovery, Hokkaido University, Kita 21, Nishi 10, Kita-ku, Sapporo, 001-0021, Japan.
- PRESTO, Japan Science and Technology Agency (JST), 4-1-8, Honcho, Kawaguchi, Saitama, 332-0012, Japan.
| | - Tomohiro Yamazaki
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, 565-0871, Japan.
| | - Kensuke Ninomiya
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, 565-0871, Japan
| | - Tetsuro Hirose
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, 565-0871, Japan
- Institute for Open and Transdisciplinary Research Initiatives, Osaka University, 1-3 Yamadaoka, Suita, 565-0871, Japan
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33
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Ripin N, Parker R. Formation, function, and pathology of RNP granules. Cell 2023; 186:4737-4756. [PMID: 37890457 PMCID: PMC10617657 DOI: 10.1016/j.cell.2023.09.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 07/28/2023] [Accepted: 09/07/2023] [Indexed: 10/29/2023]
Abstract
Ribonucleoprotein (RNP) granules are diverse membrane-less organelles that form through multivalent RNA-RNA, RNA-protein, and protein-protein interactions between RNPs. RNP granules are implicated in many aspects of RNA physiology, but in most cases their functions are poorly understood. RNP granules can be described through four key principles. First, RNP granules often arise because of the large size, high localized concentrations, and multivalent interactions of RNPs. Second, cells regulate RNP granule formation by multiple mechanisms including posttranslational modifications, protein chaperones, and RNA chaperones. Third, RNP granules impact cell physiology in multiple manners. Finally, dysregulation of RNP granules contributes to human diseases. Outstanding issues in the field remain, including determining the scale and molecular mechanisms of RNP granule function and how granule dysfunction contributes to human disease.
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Affiliation(s)
- Nina Ripin
- Department of Biochemistry and Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Roy Parker
- Department of Biochemistry and Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA.
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34
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Cardona AH, Ecsedi S, Khier M, Yi Z, Bahri A, Ouertani A, Valero F, Labrosse M, Rouquet S, Robert S, Loubat A, Adekunle D, Hubstenberger A. Self-demixing of mRNA copies buffers mRNA:mRNA and mRNA:regulator stoichiometries. Cell 2023; 186:4310-4324.e23. [PMID: 37703874 DOI: 10.1016/j.cell.2023.08.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 06/08/2023] [Accepted: 08/16/2023] [Indexed: 09/15/2023]
Abstract
Cellular homeostasis requires the robust control of biomolecule concentrations, but how do millions of mRNAs coordinate their stoichiometries in the face of dynamic translational changes? Here, we identified a two-tiered mechanism controlling mRNA:mRNA and mRNA:protein stoichiometries where mRNAs super-assemble into condensates with buffering capacity and sorting selectivity through phase-transition mechanisms. Using C. elegans oogenesis arrest as a model, we investigated the transcriptome cytosolic reorganization through the sequencing of RNA super-assemblies coupled with single mRNA imaging. Tightly repressed mRNAs self-assembled into same-sequence nanoclusters that further co-assembled into multiphase condensates. mRNA self-sorting was concentration dependent, providing a self-buffering mechanism that is selective to sequence identity and controls mRNA:mRNA stoichiometries. The cooperative sharing of limiting translation repressors between clustered mRNAs prevented the disruption of mRNA:repressor stoichiometries in the cytosol. Robust control of mRNA:mRNA and mRNA:protein stoichiometries emerges from mRNA self-demixing and cooperative super-assembly into multiphase multiscale condensates with dynamic storage capacity.
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Affiliation(s)
| | - Szilvia Ecsedi
- Université Côte D'Azur, CNRS, Inserm, iBV, 06108 Nice, France
| | - Mokrane Khier
- Université Côte D'Azur, CNRS, Inserm, iBV, 06108 Nice, France
| | - Zhou Yi
- Université Côte D'Azur, CNRS, Inserm, iBV, 06108 Nice, France
| | - Alia Bahri
- Université Côte D'Azur, CNRS, Inserm, iBV, 06108 Nice, France
| | - Amira Ouertani
- Université Côte D'Azur, CNRS, Inserm, iBV, 06108 Nice, France
| | - Florian Valero
- Université Côte D'Azur, CNRS, Inserm, iBV, 06108 Nice, France
| | | | - Sami Rouquet
- Université Côte D'Azur, CNRS, Inserm, iBV, 06108 Nice, France
| | - Stéphane Robert
- Université Aix Marseille, Inserm, INRAE, C2VN, 13005 Marseille, France
| | - Agnès Loubat
- Université Côte D'Azur, CNRS, Inserm, iBV, 06108 Nice, France
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35
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Chawla R, Tom JKA, Boyd T, Grotjahn DA, Park D, Deniz AA, Racki LR. Reentrant DNA shells tune polyphosphate condensate size. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.13.557044. [PMID: 37745474 PMCID: PMC10515899 DOI: 10.1101/2023.09.13.557044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The ancient, inorganic biopolymer polyphosphate (polyP) occurs in all three domains of life and affects myriad cellular processes. An intriguing feature of polyP is its frequent proximity to chromatin, and in the case of many bacteria, its occurrence in the form of magnesium-enriched condensates embedded in the nucleoid, particularly in response to stress. The physical basis of the interaction between polyP and DNA, two fundamental anionic biopolymers, and the resulting effects on the organization of both the nucleoid and polyP condensates remain poorly understood. Given the essential role of magnesium ions in the coordination of polymeric phosphate species, we hypothesized that a minimal system of polyP, magnesium ions, and DNA (polyP-Mg2+-DNA) would capture key features of the interplay between the condensates and bacterial chromatin. We find that DNA can profoundly affect polyP-Mg2+ coacervation even at concentrations several orders of magnitude lower than found in the cell. The DNA forms shells around polyP-Mg2+ condensates and these shells show reentrant behavior, primarily forming in the concentration range close to polyP-Mg2+ charge neutralization. This surface association tunes both condensate size and DNA morphology in a manner dependent on DNA properties, including length and concentration. Our work identifies three components that could form the basis of a central and tunable interaction hub that interfaces with cellular interactors. These studies will inform future efforts to understand the basis of polyP granule composition and consolidation, as well as the potential capacity of these mesoscale assemblies to remodel chromatin in response to diverse stressors at different length and time scales.
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Affiliation(s)
| | | | - Tumara Boyd
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA
| | - Danielle A. Grotjahn
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA
| | - Donghyun Park
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA
| | - Ashok A. Deniz
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA
| | - Lisa R. Racki
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA
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36
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Perelman RT, Schmidt A, Khan U, Walter NG. Spontaneous Confinement of mRNA Molecules at Biomolecular Condensate Boundaries. Cells 2023; 12:2250. [PMID: 37759470 PMCID: PMC10526803 DOI: 10.3390/cells12182250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 09/01/2023] [Accepted: 09/09/2023] [Indexed: 09/29/2023] Open
Abstract
Cellular biomolecular condensates, termed ribonucleoprotein (RNP) granules, are often enriched in messenger RNA (mRNA) molecules relative to the surrounding cytoplasm. Yet, the spatial localization and diffusion of mRNAs in close proximity to phase separated RNP granules are not well understood. In this study, we performed single-molecule fluorescence imaging experiments of mRNAs in live cells in the presence of two types of RNP granules, stress granules (SGs) and processing bodies (PBs), which are distinct in their molecular composition and function. We developed a photobleaching- and noise-corrected colocalization imaging algorithm that was employed to determine the accurate positions of individual mRNAs relative to the granule's boundaries. We found that mRNAs are often localized at granule boundaries, an observation consistent with recently published data. We suggest that mRNA molecules become spontaneously confined at the RNP granule boundary similar to the adsorption of polymer molecules at liquid-liquid interfaces, which is observed in various technological and biological processes. We also suggest that this confinement could be due to a combination of intermolecular interactions associated with, first, the screening of a portion of the RNP granule interface by the polymer and, second, electrostatic interactions due to a strong electric field induced by a Donnan potential generated across the thin interface.
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Affiliation(s)
- Rebecca T. Perelman
- Single Molecule Analysis Group, University of Michigan, Ann Arbor, MI 48109, USA; (R.T.P.); (A.S.)
| | - Andreas Schmidt
- Single Molecule Analysis Group, University of Michigan, Ann Arbor, MI 48109, USA; (R.T.P.); (A.S.)
| | - Umar Khan
- Center for Advanced Biomedical Imaging and Photonics, Beth Israel Deaconess Medical Center, Harvard University, Boston, MA 02115, USA;
| | - Nils G. Walter
- Single Molecule Analysis Group, University of Michigan, Ann Arbor, MI 48109, USA; (R.T.P.); (A.S.)
- Center for RNA Biomedicine, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
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37
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Farag M, Borcherds WM, Bremer A, Mittag T, Pappu RV. Phase separation of protein mixtures is driven by the interplay of homotypic and heterotypic interactions. Nat Commun 2023; 14:5527. [PMID: 37684240 PMCID: PMC10491635 DOI: 10.1038/s41467-023-41274-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 08/29/2023] [Indexed: 09/10/2023] Open
Abstract
Prion-like low-complexity domains (PLCDs) are involved in the formation and regulation of distinct biomolecular condensates that form via phase separation coupled to percolation. Intracellular condensates often encompass numerous distinct proteins with PLCDs. Here, we combine simulations and experiments to study mixtures of PLCDs from two RNA-binding proteins, hnRNPA1 and FUS. Using simulations and experiments, we find that 1:1 mixtures of A1-LCD and FUS-LCD undergo phase separation more readily than either of the PLCDs on their own due to complementary electrostatic interactions. Tie line analysis reveals that stoichiometric ratios of different components and their sequence-encoded interactions contribute jointly to the driving forces for condensate formation. Simulations also show that the spatial organization of PLCDs within condensates is governed by relative strengths of homotypic versus heterotypic interactions. We uncover rules for how interaction strengths and sequence lengths modulate conformational preferences of molecules at interfaces of condensates formed by mixtures of proteins.
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Affiliation(s)
- Mina Farag
- Department of Biomedical Engineering and Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Wade M Borcherds
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Anne Bremer
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Tanja Mittag
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA.
| | - Rohit V Pappu
- Department of Biomedical Engineering and Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, MO, 63130, USA.
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Dhakal S, Mondal M, Mirzazadeh A, Banerjee S, Ghosh A, Rangachari V. α-Synuclein emulsifies TDP-43 prion-like domain - RNA liquid droplets to promote heterotypic amyloid fibrils. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.23.554502. [PMID: 37662377 PMCID: PMC10473755 DOI: 10.1101/2023.08.23.554502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Many neurodegenerative diseases including frontotemporal lobar degeneration (FTLD), Lewy body disease (LBD), multiple system atrophy (MSA), etc., show colocalized deposits of TDP-43 and α-synuclein (αS) aggregates. To understand whether these colocalizations are driven by specific molecular interactions between the two proteins, we previously showed that the prion-like C-terminal domain of TDP-43 (TDP-43PrLD) and αS synergistically interact to form neurotoxic heterotypic amyloids in homogeneous buffer conditions. However, it remains unclear whether and how αS modulates TDP-43 present within liquid droplets and biomolecular condensates called stress granules (SGs). Here, using cell culture and in vitro TDP-43PrLD - RNA liquid droplets as models along with microscopy, nanoscale spatially-resolved spectroscopy, and other biophysical analyses, we uncover the interactions of αS with phase-separated droplets. We learn that αS acts as a Pickering agent by forming clusters on the surface of TDP-43PrLD - RNA droplets and emulsifying them. The 'hardening' of the droplets that follow by αS aggregates on the periphery, nucleates the formation of heterotypic TDP-43PrLD amyloid fibrils with structures distinct from those derived from homogenous solutions. Together, these results reveal an intriguing property of αS as a Pickering agent in interacting with SGs and unmask the hitherto unknown role of αS in modulating TDP-43 proteinopathies.
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Affiliation(s)
- Shailendra Dhakal
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg MS 39406, USA
- Center for Molecular and Cellular Biosciences, University of Southern Mississippi, Hattiesburg MS 39406, USA
| | - Malay Mondal
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg MS 39406, USA
- Center for Molecular and Cellular Biosciences, University of Southern Mississippi, Hattiesburg MS 39406, USA
| | - Azin Mirzazadeh
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg MS 39406, USA
- Center for Molecular and Cellular Biosciences, University of Southern Mississippi, Hattiesburg MS 39406, USA
| | - Siddhartha Banerjee
- Department of Chemistry and Biochemistry, University of Alabama, Tuscaloosa, AL 35401, USA
| | - Ayanjeet Ghosh
- Department of Chemistry and Biochemistry, University of Alabama, Tuscaloosa, AL 35401, USA
| | - Vijayaraghavan Rangachari
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg MS 39406, USA
- Center for Molecular and Cellular Biosciences, University of Southern Mississippi, Hattiesburg MS 39406, USA
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39
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Ogunmowo T, Hoffmann C, Pepper R, Wang H, Gowrisankaran S, Ho A, Raychaudhuri S, Cooper BH, Milosevic I, Milovanovic D, Watanabe S. Intersectin and Endophilin condensates prime synaptic vesicles for release site replenishment. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.22.554276. [PMID: 37662300 PMCID: PMC10473601 DOI: 10.1101/2023.08.22.554276] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Neurotransmitter is released from dedicated sites of synaptic vesicle fusion within a synapse. Following fusion, the vacated sites are replenished immediately by new vesicles for subsequent neurotransmission. These replacement vesicles are assumed to be located near release sites and used by chance. Here, we find that replacement vesicles are clustered around this region by Intersectin-1. Specifically, Intersectin-1 forms dynamic molecular condensates with Endophilin A1 near release sites and sequesters vesicles around this region. In the absence of Intersectin-1, vesicles within 20 nm of the plasma membrane are reduced, and consequently, vacated sites cannot be replenished rapidly, leading to depression of synaptic transmission. Similarly, mutations in Intersectin-1 that disrupt Endophilin A1 binding result in similar phenotypes. However, in the absence of Endophilin, this replacement pool of vesicles is available but cannot be accessed, suggesting that Endophilin A1 is needed to mobilize these vesicles. Thus, our work describes a distinct physical region within a synapse where replacement vesicles are harbored for release site replenishment.
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Affiliation(s)
- Tyler Ogunmowo
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD USA
| | - Christian Hoffmann
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Renee Pepper
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD USA
| | - Han Wang
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | | | - Annie Ho
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD USA
| | - Sumana Raychaudhuri
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD USA
| | - Benjamin H. Cooper
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Ira Milosevic
- Multidisciplinary Institute of Ageing, University of Coimbra, Coimbra, Portugal
- Nuffield Department of Medicine, Wellcome Centre for Human Genetics, NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, UK
| | - Dragomir Milovanovic
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
- Einstein Center for Neuroscience, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität Berlin, and Berlin Institute of Health, 10117 Berlin, Germany
| | - Shigeki Watanabe
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD USA
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD USA
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40
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Parra AS, Moezzi CA, Johnston CA. Drosophila Adducin facilitates phase separation and function of a conserved spindle orientation complex. Front Cell Dev Biol 2023; 11:1220529. [PMID: 37655159 PMCID: PMC10467427 DOI: 10.3389/fcell.2023.1220529] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 08/08/2023] [Indexed: 09/02/2023] Open
Abstract
Asymmetric cell division (ACD) allows stem cells to generate differentiating progeny while simultaneously maintaining their own pluripotent state. ACD involves coupling mitotic spindle orientation with cortical polarity cues to direct unequal segregation of cell fate determinants. In Drosophila neural stem cells (neuroblasts; NBs), spindles orient along an apical-basal polarity axis through a conserved complex of Partner of Inscuteable (Pins; human LGN) and Mushroom body defect (Mud; human NuMA). While many details of its function are well known, the molecular mechanics that drive assembly of the cortical Pins/Mud complex remain unclear, particularly with respect to the mutually exclusive Pins complex formed with the apical scaffold protein Inscuteable (Insc). Here we identify Hu li tai shao (Hts; human Adducin) as a direct Mud-binding protein, using an aldolase fold within its head domain (HtsHEAD) to bind a short Mud coiled-coil domain (MudCC) that is adjacent to the Pins-binding domain (MudPBD). Hts is expressed throughout the larval central brain and apically polarizes in mitotic NBs where it is required for Mud-dependent spindle orientation. In vitro analyses reveal that Pins undergoes liquid-liquid phase separation with Mud, but not with Insc, suggesting a potential molecular basis for differential assembly mechanics between these two competing apical protein complexes. Furthermore, we find that Hts binds an intact Pins/Mud complex, reduces the concentration threshold for its phase separation, and alters the liquid-like property of the resulting phase separated droplets. Domain mapping and mutational analyses implicate critical roles for both multivalent interactions (via MudCC oligomerization) and protein disorder (via an intrinsically disordered region in Hts; HtsIDR) in phase separation of the Hts/Mud/Pins complex. Our study identifies a new component of the spindle positioning machinery in NBs and suggests that phase separation of specific protein complexes might regulate ordered assembly within the apical domain to ensure proper signaling output.
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41
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Lan C, Kim J, Ulferts S, Aprile-Garcia F, Weyrauch S, Anandamurugan A, Grosse R, Sawarkar R, Reinhardt A, Hugel T. Quantitative real-time in-cell imaging reveals heterogeneous clusters of proteins prior to condensation. Nat Commun 2023; 14:4831. [PMID: 37582808 PMCID: PMC10427612 DOI: 10.1038/s41467-023-40540-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 07/26/2023] [Indexed: 08/17/2023] Open
Abstract
Our current understanding of biomolecular condensate formation is largely based on observing the final near-equilibrium condensate state. Despite expectations from classical nucleation theory, pre-critical protein clusters were recently shown to form under subsaturation conditions in vitro; if similar long-lived clusters comprising more than a few molecules are also present in cells, our understanding of the physical basis of biological phase separation may fundamentally change. Here, we combine fluorescence microscopy with photobleaching analysis to quantify the formation of clusters of NELF proteins in living, stressed cells. We categorise small and large clusters based on their dynamics and their response to p38 kinase inhibition. We find a broad distribution of pre-condensate cluster sizes and show that NELF protein cluster formation can be explained as non-classical nucleation with a surprisingly flat free-energy landscape for a wide range of sizes and an inhibition of condensation in unstressed cells.
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Affiliation(s)
- Chenyang Lan
- Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany
- BIOSS and CIBSS Signalling Research Centres, University of Freiburg, Freiburg, Germany
- PicoQuant GmbH, Rudower Chaussee 29, 12489, Berlin, Germany
| | - Juhyeong Kim
- Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany
| | - Svenja Ulferts
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | | | - Sophie Weyrauch
- Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany
- Faculty of Chemistry and Pharmacology, University of Freiburg, Freiburg, Germany
| | | | - Robert Grosse
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | - Ritwick Sawarkar
- Medical Research Council (MRC), University of Cambridge, Cambridge, CB2 1QR, United Kingdom
| | - Aleks Reinhardt
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, United Kingdom.
| | - Thorsten Hugel
- Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany.
- BIOSS and CIBSS Signalling Research Centres, University of Freiburg, Freiburg, Germany.
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42
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Toledo PL, Gianotti AR, Vazquez DS, Ermácora MR. Protein nanocondensates: the next frontier. Biophys Rev 2023; 15:515-530. [PMID: 37681092 PMCID: PMC10480383 DOI: 10.1007/s12551-023-01105-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 07/21/2023] [Indexed: 09/09/2023] Open
Abstract
Over the past decade, myriads of studies have highlighted the central role of protein condensation in subcellular compartmentalization and spatiotemporal organization of biological processes. Conceptually, protein condensation stands at the highest level in protein structure hierarchy, accounting for the assembly of bodies ranging from thousands to billions of molecules and for densities ranging from dense liquids to solid materials. In size, protein condensates range from nanocondensates of hundreds of nanometers (mesoscopic clusters) to phase-separated micron-sized condensates. In this review, we focus on protein nanocondensation, a process that can occur in subsaturated solutions and can nucleate dense liquid phases, crystals, amorphous aggregates, and fibers. We discuss the nanocondensation of proteins in the light of general physical principles and examine the biophysical properties of several outstanding examples of nanocondensation. We conclude that protein nanocondensation cannot be fully explained by the conceptual framework of micron-scale biomolecular condensation. The evolution of nanocondensates through changes in density and order is currently under intense investigation, and this should lead to the development of a general theoretical framework, capable of encompassing the full range of sizes and densities found in protein condensates.
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Affiliation(s)
- Pamela L. Toledo
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, 1876, Bernal, Buenos Aires, Argentina
- Grupo de Biología Estructural y Biotecnología, IMBICE, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
| | - Alejo R. Gianotti
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, 1876, Bernal, Buenos Aires, Argentina
- Grupo de Biología Estructural y Biotecnología, IMBICE, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
| | - Diego S. Vazquez
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, 1876, Bernal, Buenos Aires, Argentina
- Grupo de Biología Estructural y Biotecnología, IMBICE, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
| | - Mario R. Ermácora
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, 1876, Bernal, Buenos Aires, Argentina
- Grupo de Biología Estructural y Biotecnología, IMBICE, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
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43
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Hou XN, Tang C. The pros and cons of ubiquitination on the formation of protein condensates. Acta Biochim Biophys Sin (Shanghai) 2023; 55:1084-1098. [PMID: 37294105 PMCID: PMC10423694 DOI: 10.3724/abbs.2023096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 03/19/2023] [Indexed: 06/10/2023] Open
Abstract
Ubiquitination, a post-translational modification that attaches one or more ubiquitin (Ub) molecules to another protein, plays a crucial role in the phase-separation processes. Ubiquitination can modulate the formation of membrane-less organelles in two ways. First, a scaffold protein drives phase separation, and Ub is recruited to the condensates. Second, Ub actively phase-separates through the interactions with other proteins. Thus, the role of ubiquitination and the resulting polyUb chains ranges from bystanders to active participants in phase separation. Moreover, long polyUb chains may be the primary driving force for phase separation. We further discuss that the different roles can be determined by the lengths and linkages of polyUb chains which provide preorganized and multivalent binding platforms for other client proteins. Together, ubiquitination adds a new layer of regulation for the flow of material and information upon cellular compartmentalization of proteins.
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Affiliation(s)
- Xue-Ni Hou
- Beijing National Laboratory for Molecular SciencesCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing100871China
| | - Chun Tang
- Beijing National Laboratory for Molecular SciencesCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing100871China
- Center for Quantitate BiologyPKU-Tsinghua Center for Life ScienceAcademy for Advanced Interdisciplinary StudiesPeking UniversityBeijing100871China
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44
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Dai Y, Chamberlayne CF, Messina MS, Chang CJ, Zare RN, You L, Chilkoti A. Interface of biomolecular condensates modulates redox reactions. Chem 2023; 9:1594-1609. [PMID: 37546704 PMCID: PMC10399281 DOI: 10.1016/j.chempr.2023.04.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Biomolecular condensates mediate diverse cellular processes. The density transition process of condensate formation results in selective partitioning of molecules, which define a distinct chemical environment within the condensates. However, the fundamental features of the chemical environment and the mechanisms by which such environment can contribute to condensate functions have not been revealed. Here, we report that an electric potential gradient, thereby an electric field, is established at the liquid-liquid interface between the condensate and the bulk environment due to the density transition of ions and molecules brought about by phase separation. We find that the interface of condensates can drive spontaneous redox reactions in vitro and in living cells. Our results uncover a fundamental physicochemical property of the interface of condensates and the mechanism by which the interface can modulate biochemical activities.
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Affiliation(s)
- Yifan Dai
- Department of Biomedical Engineering, Duke University, Durham, NC, 27705
| | | | - Marco S. Messina
- Department of Chemistry, University of California, Berkeley, CA, 94720
| | | | - Richard N. Zare
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Lingchong You
- Department of Biomedical Engineering, Duke University, Durham, NC, 27705
| | - Ashutosh Chilkoti
- Department of Biomedical Engineering, Duke University, Durham, NC, 27705
- Lead Contact
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45
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Shinn MK, Pappu RV. Soaping up transcriptional condensates. Dev Cell 2023; 58:915-916. [PMID: 37279696 DOI: 10.1016/j.devcel.2023.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 05/09/2023] [Accepted: 05/10/2023] [Indexed: 06/08/2023]
Abstract
The condensate-forming ability of transcription factors (TFs) has received considerable attention, although how condensates function in transcription remains unclear. In this issue of Developmental Cell, Wang et al. show that target DNA and transcriptional regulators work as soap-like surfactants to adsorb on condensates, affecting the activities of transcriptional condensates.
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Affiliation(s)
- Min Kyung Shinn
- Department of Biomedical Engineering and Center for Biomolecular Condensates, James F. McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Rohit V Pappu
- Department of Biomedical Engineering and Center for Biomolecular Condensates, James F. McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA.
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46
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Law JO, Jones CM, Stevenson T, Williamson TA, Turner MS, Kusumaatmaja H, Grellscheid SN. A bending rigidity parameter for stress granule condensates. SCIENCE ADVANCES 2023; 9:eadg0432. [PMID: 37196085 DOI: 10.1126/sciadv.adg0432] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 04/12/2023] [Indexed: 05/19/2023]
Abstract
Interfacial tension plays an important role in governing the dynamics of droplet coalescence and determining how condensates interact with and deform lipid membranes and biological filaments. We demonstrate that an interfacial tension-only model is inadequate for describing stress granules in live cells. Harnessing a high-throughput flicker spectroscopy pipeline to analyze the shape fluctuations of tens of thousands of stress granules, we find that the measured fluctuation spectra require an additional contribution, which we attribute to elastic bending deformation. We also show that stress granules have an irregular, nonspherical base shape. These results suggest that stress granules are viscoelastic droplets with a structured interface, rather than simple Newtonian liquids. Furthermore, we observe that the measured interfacial tensions and bending rigidities span a range of several orders of magnitude. Hence, different types of stress granules (and more generally, other biomolecular condensates) can only be differentiated via large-scale surveys.
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Affiliation(s)
- Jack O Law
- Computational Biology Unit and Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Carl M Jones
- Computational Biology Unit and Department of Biological Sciences, University of Bergen, Bergen, Norway
- Department of Biosciences, University of Durham, Durham, UK
| | - Thomas Stevenson
- Computational Biology Unit and Department of Biological Sciences, University of Bergen, Bergen, Norway
| | | | | | | | - Sushma N Grellscheid
- Computational Biology Unit and Department of Biological Sciences, University of Bergen, Bergen, Norway
- Department of Biosciences, University of Durham, Durham, UK
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47
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Kurusu R, Fujimoto Y, Morishita H, Noshiro D, Takada S, Yamano K, Tanaka H, Arai R, Kageyama S, Funakoshi T, Komatsu-Hirota S, Taka H, Kazuno S, Miura Y, Koike M, Wakai T, Waguri S, Noda NN, Komatsu M. Integrated proteomics identifies p62-dependent selective autophagy of the supramolecular vault complex. Dev Cell 2023:S1534-5807(23)00191-0. [PMID: 37192622 DOI: 10.1016/j.devcel.2023.04.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 03/13/2023] [Accepted: 04/25/2023] [Indexed: 05/18/2023]
Abstract
In addition to membranous organelles, autophagy selectively degrades biomolecular condensates, in particular p62/SQSTM1 bodies, to prevent diseases including cancer. Evidence is growing regarding the mechanisms by which autophagy degrades p62 bodies, but little is known about their constituents. Here, we established a fluorescence-activated-particle-sorting-based purification method for p62 bodies using human cell lines and determined their constituents by mass spectrometry. Combined with mass spectrometry of selective-autophagy-defective mouse tissues, we identified vault, a large supramolecular complex, as a cargo within p62 bodies. Mechanistically, major vault protein directly interacts with NBR1, a p62-interacting protein, to recruit vault into p62 bodies for efficient degradation. This process, named vault-phagy, regulates homeostatic vault levels in vivo, and its impairment may be associated with non-alcoholic-steatohepatitis-derived hepatocellular carcinoma. Our study provides an approach to identifying phase-separation-mediated selective autophagy cargoes, expanding our understanding of the role of phase separation in proteostasis.
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Affiliation(s)
- Reo Kurusu
- Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Yuki Fujimoto
- Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Hideaki Morishita
- Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan.
| | - Daisuke Noshiro
- Institute for Genetic Medicine, Hokkaido University, Sapporo 060-0815, Japan
| | - Shuhei Takada
- Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Koji Yamano
- Department of Biomolecular Pathogenesis, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Hideaki Tanaka
- Laboratory for Protein Crystallography, Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - Ritsuko Arai
- Department of Anatomy and Histology, Fukushima Medical University School of Medicine, Hikarigaoka, Fukushima 960-1295, Japan
| | - Shun Kageyama
- Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Tomoko Funakoshi
- Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Satoko Komatsu-Hirota
- Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Hikari Taka
- Laboratory of Proteomics and Biomolecular Science, Biomedical Research Core Facilities, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Saiko Kazuno
- Laboratory of Proteomics and Biomolecular Science, Biomedical Research Core Facilities, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Yoshiki Miura
- Laboratory of Proteomics and Biomolecular Science, Biomedical Research Core Facilities, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Masato Koike
- Department of Cell Biology and Neuroscience, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Toshifumi Wakai
- Division of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata City, Niigata 951-8510, Japan
| | - Satoshi Waguri
- Department of Anatomy and Histology, Fukushima Medical University School of Medicine, Hikarigaoka, Fukushima 960-1295, Japan
| | - Nobuo N Noda
- Institute for Genetic Medicine, Hokkaido University, Sapporo 060-0815, Japan
| | - Masaaki Komatsu
- Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan.
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48
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Pappu R, Farag M, Borcherds W, Bremer A, Mittag T. Phase Separation in Mixtures of Prion-Like Low Complexity Domains is Driven by the Interplay of Homotypic and Heterotypic Interactions. RESEARCH SQUARE 2023:rs.3.rs-2870258. [PMID: 37205474 PMCID: PMC10187436 DOI: 10.21203/rs.3.rs-2870258/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Prion-like low-complexity domains (PLCDs) are involved in the formation and regulation of distinct biomolecular condensates that form via coupled associative and segregative phase transitions. We previously deciphered how evolutionarily conserved sequence features drive phase separation of PLCDs through homotypic interactions. However, condensates typically encompass a diverse mixture of proteins with PLCDs. Here, we combine simulations and experiments to study mixtures of PLCDs from two RNA binding proteins namely, hnRNPA1 and FUS. We find that 1:1 mixtures of the A1-LCD and FUS-LCD undergo phase separation more readily than either of the PLCDs on their own. The enhanced driving forces for phase separation of mixtures of A1-LCD and FUS-LCD arise partly from complementary electrostatic interactions between the two proteins. This complex coacervation-like mechanism adds to complementary interactions among aromatic residues. Further, tie line analysis shows that stoichiometric ratios of different components and their sequence-encoded interactions jointly contribute to the driving forces for condensate formation. These results highlight how expression levels might be tuned to regulate the driving forces for condensate formation in vivo . Simulations also show that the organization of PLCDs within condensates deviates from expectations based on random mixture models. Instead, spatial organization within condensates will reflect the relative strengths of homotypic versus heterotypic interactions. We also uncover rules for how interaction strengths and sequence lengths modulate conformational preferences of molecules at interfaces of condensates formed by mixtures of proteins. Overall, our findings emphasize the network-like organization of molecules within multicomponent condensates, and the distinctive, composition-specific conformational features of condensate interfaces.
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Yu M, Heidari M, Mikhaleva S, Tan PS, Mingu S, Ruan H, Reinkemeier CD, Obarska-Kosinska A, Siggel M, Beck M, Hummer G, Lemke EA. Visualizing the disordered nuclear transport machinery in situ. Nature 2023; 617:162-169. [PMID: 37100914 PMCID: PMC10156602 DOI: 10.1038/s41586-023-05990-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 03/21/2023] [Indexed: 04/28/2023]
Abstract
The approximately 120 MDa mammalian nuclear pore complex (NPC) acts as a gatekeeper for the transport between the nucleus and cytosol1. The central channel of the NPC is filled with hundreds of intrinsically disordered proteins (IDPs) called FG-nucleoporins (FG-NUPs)2,3. Although the structure of the NPC scaffold has been resolved in remarkable detail, the actual transport machinery built up by FG-NUPs-about 50 MDa-is depicted as an approximately 60-nm hole in even highly resolved tomograms and/or structures computed with artificial intelligence4-11. Here we directly probed conformations of the vital FG-NUP98 inside NPCs in live cells and in permeabilized cells with an intact transport machinery by using a synthetic biology-enabled site-specific small-molecule labelling approach paired with highly time-resolved fluorescence microscopy. Single permeabilized cell measurements of the distance distribution of FG-NUP98 segments combined with coarse-grained molecular simulations of the NPC allowed us to map the uncharted molecular environment inside the nanosized transport channel. We determined that the channel provides-in the terminology of the Flory polymer theory12-a 'good solvent' environment. This enables the FG domain to adopt expanded conformations and thus control transport between the nucleus and cytoplasm. With more than 30% of the proteome being formed from IDPs, our study opens a window into resolving disorder-function relationships of IDPs in situ, which are important in various processes, such as cellular signalling, phase separation, ageing and viral entry.
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Affiliation(s)
- Miao Yu
- Biocenter, Johannes Gutenberg University Mainz, Mainz, Germany
- Institute of Molecular Biology Mainz, Mainz, Germany
- Structural and Computational Biology, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Maziar Heidari
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Sofya Mikhaleva
- Biocenter, Johannes Gutenberg University Mainz, Mainz, Germany
- Institute of Molecular Biology Mainz, Mainz, Germany
- Structural and Computational Biology, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Piau Siong Tan
- Structural and Computational Biology, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Sara Mingu
- Biocenter, Johannes Gutenberg University Mainz, Mainz, Germany
- Institute of Molecular Biology Mainz, Mainz, Germany
| | - Hao Ruan
- Biocenter, Johannes Gutenberg University Mainz, Mainz, Germany
- Institute of Molecular Biology Mainz, Mainz, Germany
| | - Christopher D Reinkemeier
- Biocenter, Johannes Gutenberg University Mainz, Mainz, Germany
- Institute of Molecular Biology Mainz, Mainz, Germany
- Structural and Computational Biology, European Molecular Biology Laboratory, Heidelberg, Germany
| | | | - Marc Siggel
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
- Centre for Structural Systems Biology, Hamburg, Germany
- European Molecular Biology Laboratory Hamburg, Hamburg, Germany
| | - Martin Beck
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
- Institute of Biophysics, Goethe University Frankfurt, Frankfurt am Main, Germany.
| | - Edward A Lemke
- Biocenter, Johannes Gutenberg University Mainz, Mainz, Germany.
- Institute of Molecular Biology Mainz, Mainz, Germany.
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Dai Y, You L, Chilkoti A. Engineering synthetic biomolecular condensates. NATURE REVIEWS BIOENGINEERING 2023; 1:1-15. [PMID: 37359769 PMCID: PMC10107566 DOI: 10.1038/s44222-023-00052-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 03/06/2023] [Indexed: 06/28/2023]
Abstract
The concept of phase-separation-mediated formation of biomolecular condensates provides a new framework to understand cellular organization and cooperativity-dependent cellular functions. With growing understanding of how biological systems drive phase separation and how cellular functions are encoded by biomolecular condensates, opportunities have emerged for cellular control through engineering of synthetic biomolecular condensates. In this Review, we discuss how to construct synthetic biomolecular condensates and how they can regulate cellular functions. We first describe the fundamental principles by which biomolecular components can drive phase separation. Next, we discuss the relationship between the properties of condensates and their cellular functions, which informs the design of components to create programmable synthetic condensates. Finally, we describe recent applications of synthetic biomolecular condensates for cellular control and discuss some of the design considerations and prospective applications.
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Affiliation(s)
- Yifan Dai
- Department of Biomedical Engineering, Duke University, Durham, NC USA
| | - Lingchong You
- Department of Biomedical Engineering, Duke University, Durham, NC USA
| | - Ashutosh Chilkoti
- Department of Biomedical Engineering, Duke University, Durham, NC USA
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