1
|
Weakly HMJ, Keller SL. Coupling liquid phases in 3D condensates and 2D membranes: Successes, challenges, and tools. Biophys J 2024; 123:1329-1341. [PMID: 38160256 PMCID: PMC11163299 DOI: 10.1016/j.bpj.2023.12.023] [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: 09/21/2023] [Revised: 12/05/2023] [Accepted: 12/26/2023] [Indexed: 01/03/2024] Open
Abstract
This review describes the major experimental challenges researchers meet when attempting to couple phase separation between membranes and condensates. Although it is well known that phase separation in a 2D membrane could affect molecules capable of forming a 3D condensate (and vice versa), few researchers have quantified the effects to date. The scarcity of these measurements is not due to a lack of intense interest or effort in the field. Rather, it reflects significant experimental challenges in manipulating coupled membranes and condensates to yield quantitative values. These challenges transcend many molecular details, which means they impact a wide range of systems. This review highlights recent exciting successes in the field, and it lays out a comprehensive list of tools that address potential pitfalls for researchers who are considering coupling membranes with condensates.
Collapse
Affiliation(s)
- Heidi M J Weakly
- Department of Chemistry, University of Washington - Seattle, Seattle, Washington
| | - Sarah L Keller
- Department of Chemistry, University of Washington - Seattle, Seattle, Washington.
| |
Collapse
|
2
|
Wang J, Zhu H, Tian R, Zhang Q, Zhang H, Hu J, Wang S. Physiological and pathological effects of phase separation in the central nervous system. J Mol Med (Berl) 2024; 102:599-615. [PMID: 38441598 PMCID: PMC11055734 DOI: 10.1007/s00109-024-02435-7] [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: 05/01/2023] [Revised: 02/14/2024] [Accepted: 02/20/2024] [Indexed: 04/28/2024]
Abstract
Phase separation, also known as biomolecule condensate, participates in physiological processes such as transcriptional regulation, signal transduction, gene expression, and DNA damage repair by creating a membrane-free compartment. Phase separation is primarily caused by the interaction of multivalent non-covalent bonds between proteins and/or nucleic acids. The strength of molecular multivalent interaction can be modified by component concentration, the potential of hydrogen, posttranslational modification, and other factors. Notably, phase separation occurs frequently in the cytoplasm of mitochondria, the nucleus, and synapses. Phase separation in vivo is dynamic or stable in the normal physiological state, while abnormal phase separation will lead to the formation of biomolecule condensates, speeding up the disease progression. To provide candidate suggestions for the clinical treatment of nervous system diseases, this review, based on existing studies, carefully and systematically represents the physiological roles of phase separation in the central nervous system and its pathological mechanism in neurodegenerative diseases.
Collapse
Affiliation(s)
- Jiaxin Wang
- Department of Anesthesiology, First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001, People's Republic of China
- School of Medicine, Xiamen University, Xiamen, Fujian, 361000, People's Republic of China
| | - Hongrui Zhu
- Department of Anesthesiology, First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001, People's Republic of China.
- Core Facility Center, The First Affiliated Hospital of USTC (Anhui Provincial Hospital), Hefei, China.
| | - Ruijia Tian
- School of Medicine, Xiamen University, Xiamen, Fujian, 361000, People's Republic of China
| | - Qian Zhang
- School of Medicine, Xiamen University, Xiamen, Fujian, 361000, People's Republic of China
| | - Haoliang Zhang
- School of Medicine, Xiamen University, Xiamen, Fujian, 361000, People's Republic of China
| | - Jin Hu
- School of Medicine, Xiamen University, Xiamen, Fujian, 361000, People's Republic of China
| | - Sheng Wang
- Department of Anesthesiology, First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001, People's Republic of China.
| |
Collapse
|
3
|
Sakuma Y, Kayamori N, Tanaka J, Haga K, Imai M, Kawakatsu T. Effects of grafted polymers on the lipid membrane fluidity. Biophys J 2024; 123:489-501. [PMID: 38243595 PMCID: PMC10912922 DOI: 10.1016/j.bpj.2024.01.014] [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: 03/31/2023] [Revised: 07/27/2023] [Accepted: 01/12/2024] [Indexed: 01/21/2024] Open
Abstract
Since the membrane fluidity controls the cellular functions, it is important to identify the factors that determine the cell membrane viscosity. Cell membranes are composed of not only lipids and proteins but also polysaccharide chain-anchored molecules, such as glycolipids. To reveal the effects of grafted polymers on the membrane fluidity, in this study, we measured the membrane viscosity of polymer-grafted giant unilamellar vesicles (GUVs), which were prepared by introducing the poly (ethylene glycol) (PEG)-anchored lipids to the ternary GUVs composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), and cholesterol. The membrane viscosity was obtained from the velocity field on the GUV generated by applying a point force, based on the hydrodynamic model proposed by Henle and Levine. The velocity field was visualized by a motion of the circular liquid ordered (Lo) domains formed by a phase separation. With increasing PEG density, the membrane viscosity of PEG-grafted GUVs increased gradually in the mushroom region and significantly in the brush region. We propose a hydrodynamic model that includes the excluded volume effect of PEG chains to explain the increase in membrane viscosity in the mushroom region. This work provides a basic understanding of how grafted polymers affect the membrane fluidity.
Collapse
Affiliation(s)
- Yuka Sakuma
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, Japan.
| | - Nana Kayamori
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, Japan
| | - Julia Tanaka
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, Japan
| | - Kenya Haga
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, Japan
| | - Masayuki Imai
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, Japan
| | - Toshihiro Kawakatsu
- Department of Physics, Graduate School of Science, Tohoku University, Sendai, Japan
| |
Collapse
|
4
|
Bandyopadhyay S, Gurjar D, Saha B, Bodhale N. Decoding the contextual duality of CD40 functions. Hum Immunol 2023; 84:590-599. [PMID: 37596136 DOI: 10.1016/j.humimm.2023.08.142] [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: 05/20/2023] [Revised: 07/13/2023] [Accepted: 08/11/2023] [Indexed: 08/20/2023]
Abstract
Previously, we established that as a function of its mode of interaction with its ligand or cellular conditions such as membrane lipids, preexisting signaling intermediates activation status, a transmembrane receptor, as represented here with CD40, can induce counteractive cellular responses. Using CD40-binding peptides, recombinant mutated CD40-ligands, and an agonistic antibody, we have established the functional duality of CD40. CD40 builds up two constitutionally different signalosomes on lipid raft and non-raft membrane domains initiating two different signaling pathways. Although this initial signaling may be modified by the pre-existing signaling conditions downstream and may be subjected to feed-forward or negative signaling effects, the initial CD40-CD40L interaction plays a crucial role in the functional outcome of CD40. Herein, we have reviewed the influence of interaction between the CD40-CD40L evoking the functional duality of CD40 contingent upon different physiological states of the cells.
Collapse
Affiliation(s)
| | - Dhiraj Gurjar
- National Centre for Cell Science, Ganeshkhind, Pune 411007, India
| | - Bhaskar Saha
- National Centre for Cell Science, Ganeshkhind, Pune 411007, India
| | - Neelam Bodhale
- National Centre for Cell Science, Ganeshkhind, Pune 411007, India
| |
Collapse
|
5
|
Wang Y, Majd S. Charged Lipids Modulate the Phase Separation in Multicomponent Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:11371-11378. [PMID: 37485979 DOI: 10.1021/acs.langmuir.3c01199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
Phase separation in lipid membranes controls the organization of membrane components and thus regulates membrane-mediated processes. Membrane phase behavior is influenced by the molecular properties of its components and their relative concentrations. Charged lipid species are among the most essential components of lipid membranes, and their impact on the membrane phase behavior is yet to be fully understood. Aiming to provide insight into this impact, this paper investigates how the presence and amount of anionic and cationic lipids affect the phase behavior of multicomponent membranes. Membranes of ternary composition DOPC:DPPC:Chol with two distinct molar ratios were used to test the hypothesis that inclusion of charged lipids with saturated tails, beyond a certain concentration, would impede phase separation in an otherwise phase-separating membrane. Fluorescence microscopy examination of electroformed giant liposomes revealed that when more than half of DOPC in the examined mixtures was replaced with DOPA or DOTAP, phase separation in liposomes was somewhat suppressed, and this effect increased with increasing charged lipid content. This effect depended on the membrane surface charge density as the half-maximal effect was observed at around 0.0072 C Å-2 in all examined cases. The phase-separation suppressing effect of DOPA was neutralized when oppositely charged lipid DOTAP was included in the mixture. Likewise, presence of divalent cation Ca2+ in the solution neutralized the impact of negatively charged DOPA. These results underline the detrimental influence of surface charge density on membrane phase behavior. More importantly, these findings suggest that the charged lipid content in membranes may be a regulator of their phase behavior and open new opportunities for the design of synthetic lipid membranes.
Collapse
Affiliation(s)
- Yifei Wang
- Department of Biomedical Engineering, University of Houston, 3551 Cullen Boulevard, Houston, Texas 77204, United States
| | - Sheereen Majd
- Department of Biomedical Engineering, University of Houston, 3551 Cullen Boulevard, Houston, Texas 77204, United States
| |
Collapse
|
6
|
Vu TQ, Sant'Anna LE, Kamat NP. Tuning Targeted Liposome Avidity to Cells via Lipid Phase Separation. Biomacromolecules 2023; 24:1574-1584. [PMID: 36943688 PMCID: PMC10874583 DOI: 10.1021/acs.biomac.2c01338] [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: 03/23/2023]
Abstract
The addition of both cell-targeting moieties and polyethylene glycol (PEG) to nanoparticle (NP) drug delivery systems is a standard approach to improve the biodistribution, specificity, and uptake of therapeutic cargo. The spatial presentation of these molecules affects avidity of the NP to target cells in part through an interplay between the local ligand concentration and the steric hindrance imposed by PEG molecules. Here, we show that lipid phase separation in nanoparticles can modulate liposome avidity by changing the proximity of PEG and targeting protein molecules on a nanoparticle surface. Using lipid-anchored nickel-nitrilotriacetic acid (Ni-NTA) as a model ligand, we demonstrate that the attachment of lipid anchored Ni-NTA and PEG molecules to distinct lipid domains in nanoparticles can enhance liposome binding to cancer cells by increasing ligand clustering and reducing steric hindrance. We then use this technique to enhance the binding of RGD-modified liposomes, which can bind to integrins overexpressed on many cancer cells. These results demonstrate the potential of lipid phase separation to modulate the spatial presentation of targeting and shielding molecules on lipid nanocarriers, offering a powerful tool to enhance the efficacy of NP drug delivery systems.
Collapse
Affiliation(s)
- Timothy Q Vu
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Center for Synthetic Biology, McCormick School of Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Lucas E Sant'Anna
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Center for Synthetic Biology, McCormick School of Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Neha P Kamat
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Center for Synthetic Biology, McCormick School of Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208, United States
| |
Collapse
|
7
|
Ureña J, Knight A, Lee IH. Membrane Cargo Density-Dependent Interaction between Protein and Lipid Domains on the Giant Unilamellar Vesicles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:4702-4712. [PMID: 35385290 DOI: 10.1021/acs.langmuir.2c00247] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Protein cargos anchored on the lipid membrane can be segregated by fluidic domain phase separation. Lipid membranes at certain compositions may separate into lipid domains to segregate cargos, and protein cargos themselves may be involved in protein condensate domain formation with multivalent binding proteins to segregate cargos. Recent studies suggest that these two driving forces of phase separation closely interact on the lipid membranes to promote codomain formation. In this report, we studied the effect of cargo density on the outcome of the cargo phase separation on giant unilamellar vesicles. Proteins and lipids are connected only by the anchored cargos, so it was originally hypothesized that higher cargo density would increase the degree of interaction between the lipid and protein domains, promoting more phase separation. However, fluorescence image analysis on different cargo densities showed that the cooperative domain formation and steric pressure are at a tug of war opposing each other. Cooperative domain formation is dominant under lower anchor density conditions, and above a threshold density, steric pressure was dominant opposing the domain formation. The result suggests that the cargo density is a key parameter affecting the outcome of cargo organization on the lipid membranes by phase separation.
Collapse
Affiliation(s)
- Juan Ureña
- Department of Chemistry and Biochemistry, Montclair State University, Montclair, New Jersey 07043, United States
| | - Ashlynn Knight
- Department of Biology, Montclair State University, Montclair, New Jersey 07043, United States
| | - Il-Hyung Lee
- Department of Chemistry and Biochemistry, Montclair State University, Montclair, New Jersey 07043, United States
| |
Collapse
|
8
|
Sapp K, Sodt AJ. Observed steric crowding at modest coverage requires a particular membrane-binding scheme or a complementary mechanism. Biophys J 2022; 121:430-438. [PMID: 34971618 PMCID: PMC8822614 DOI: 10.1016/j.bpj.2021.12.036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 08/21/2021] [Accepted: 12/23/2021] [Indexed: 02/03/2023] Open
Abstract
Membrane shape transitions, including fusion and fission, play an important role in many biological processes. It is therefore essential to understand mechanisms of "curvature generation," the mathematical quantification of membrane shape. Among the different mechanisms is the effect of steric pressure between proteins crowded on a surface. At a higher curvature, there is more space for the crowders and less steric pressure. Currently, the physical model of curvature induction by crowding views the proteins as being bound to the surface as a whole rather than to the underlying lipids. Here, we split the previously understood model into two pieces: first, the reduction in steric pressure due to reduced collisions between proteins, and second, the increased area available to the protein that is independent of other crowders. The cases are distinguished by how the crowder is attached to the membrane. When a protein is attached to a specific lipid, as is the case in a typical crowding experiment, one should not model its lateral entropy; this has already been accounted for by the underlying lipid. The Carnahan-Starling pressure includes this lateral entropy. The revised theory predicts that a purely entropic crowding mechanism is inconsistent with observations of reshaping at the lower range of surface coverage, suggesting that an additional mechanism is at play.
Collapse
Affiliation(s)
- Kayla Sapp
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
| | - Alexander J. Sodt
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland,Corresponding author
| |
Collapse
|
9
|
Löwe M, Kalacheva M, Boersma AJ, Kedrov A. The more the merrier: effects of macromolecular crowding on the structure and dynamics of biological membranes. FEBS J 2020; 287:5039-5067. [DOI: 10.1111/febs.15429] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 05/18/2020] [Accepted: 05/19/2020] [Indexed: 12/23/2022]
Affiliation(s)
- Maryna Löwe
- Synthetic Membrane Systems Institute of Biochemistry Heinrich Heine University Düsseldorf Germany
| | | | | | - Alexej Kedrov
- Synthetic Membrane Systems Institute of Biochemistry Heinrich Heine University Düsseldorf Germany
| |
Collapse
|
10
|
Fakhree MAA, Blum C, Claessens MMAE. Shaping membranes with disordered proteins. Arch Biochem Biophys 2019; 677:108163. [PMID: 31672499 DOI: 10.1016/j.abb.2019.108163] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 10/23/2019] [Accepted: 10/27/2019] [Indexed: 12/15/2022]
Abstract
Membrane proteins control and shape membrane trafficking processes. The role of protein structure in shaping cellular membranes is well established. However, a significant fraction of membrane proteins is disordered or contains long disordered regions. It becomes more and more clear that these disordered regions contribute to the function of membrane proteins. While the fold of a structured protein is essential for its function, being disordered seems to be a crucial feature of membrane bound intrinsically disordered proteins and protein regions. Here we outline the motifs that encode function in disordered proteins and discuss how these functional motifs enable disordered proteins to modulate membrane properties. These changes in membrane properties facilitate and regulate membrane trafficking processes which are highly abundant in eukaryotes.
Collapse
Affiliation(s)
| | - Christian Blum
- Nanobiophysics Group, University of Twente, 7522, NB, Enschede, the Netherlands
| | | |
Collapse
|
11
|
Mensch AC, Buchman JT, Haynes CL, Pedersen JA, Hamers RJ. Quaternary Amine-Terminated Quantum Dots Induce Structural Changes to Supported Lipid Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:12369-12378. [PMID: 30184424 DOI: 10.1021/acs.langmuir.8b02047] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The cytoplasmic membrane represents an essential barrier between the cytoplasm and the environment external to cells. Interaction with nanomaterials can alter the integrity of the cytoplasmic membrane through the formation of holes and membrane thinning, which can ultimately lead to adverse biological impacts. Here we use supported lipid bilayers as experimental models for the cytoplasmic membrane to investigate the impact of quantum dots functionalized with the cationic polymer poly(diallyldimethylammonium chloride) (PDDA) on membrane structure. Using a quartz crystal microbalance with dissipation monitoring we show that the positively charged quantum dots attach to and induce structural rearrangement to zwitterionic bilayers in solely the liquid-disordered phase and in those containing phase-segregated liquid-ordered domains. Real-time atomic force microscopy imaging revealed that PDDA-coated quantum dots and, to a lesser extent, PDDA itself induced the disappearance of liquid-ordered domains. We hypothesize this effect is due to an increase in energy per unit area caused by collisions between PDDA-coated quantum dots at the membrane surface. This increase in free energy per area exceeds the approximate free-energy change associated with membrane mixing between the liquid-ordered and liquid-disordered phases and results in the destabilization of membrane domains.
Collapse
Affiliation(s)
- Arielle C Mensch
- Department of Chemistry , University of Wisconsin , Madison , Wisconsin 53706 , United States
| | - Joseph T Buchman
- Department of Chemistry , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Christy L Haynes
- Department of Chemistry , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Joel A Pedersen
- Department of Chemistry , University of Wisconsin , Madison , Wisconsin 53706 , United States
- Department of Soil Science , University of Wisconsin , Madison , Wisconsin 53706 , United States
- Department of Civil and Environmental Engineering , University of Wisconsin , Madison , Wisconsin 53706 , United States
| | - Robert J Hamers
- Department of Chemistry , University of Wisconsin , Madison , Wisconsin 53706 , United States
| |
Collapse
|
12
|
Kakimoto Y, Tachihara Y, Okamoto Y, Miyazawa K, Fukuma T, Tero R. Morphology and Physical Properties of Hydrophilic-Polymer-Modified Lipids in Supported Lipid Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:7201-7209. [PMID: 29788718 DOI: 10.1021/acs.langmuir.8b00870] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Lipid molecules such as glycolipids that are modified with hydrophilic biopolymers participate in the biochemical reactions occurring on cell membranes. Their functions and efficiency are determined by the formation of microdomains and their physical properties. We investigated the morphology and properties of domains induced by the hydrophilic-polymer-modified lipid applying a polyethylene glycol (PEG)-modified lipid as a model modified lipid. We formed supported lipid bilayers (SLBs) using a 0-10 mol % range of PEG-modified lipid concentration ( CPEG). We studied their morphology and fluidity by fluorescence microscopy, the fluorescence recovery after photobleaching method, and atomic force microscopy (AFM). Fluorescence images showed that domains rich in the PEG-modified lipid appeared and SLB fluidity decreased when CPEG ≥ 5%. AFM topographies showed that clusters of the PEG-modified lipid appeared prior to domain formation and the PEG-lipid-rich domains were observed as depressions. Frequency-modulation AFM revealed a force-dependent appearance of the PEG-lipid-rich domain.
Collapse
Affiliation(s)
- Yasuhiro Kakimoto
- Department of Environmental and Life Sciences , Toyohashi University of Technology , Toyohashi , Aichi 441-8580 , Japan
| | - Yoshihiro Tachihara
- Department of Environmental and Life Sciences , Toyohashi University of Technology , Toyohashi , Aichi 441-8580 , Japan
| | - Yoshiaki Okamoto
- Department of Environmental and Life Sciences , Toyohashi University of Technology , Toyohashi , Aichi 441-8580 , Japan
| | - Keisuke Miyazawa
- Division of Electrical Engineering and Computer Science , Kanazawa University , Kakuma-machi, Kanazawa 920-1192 , Japan
| | - Takeshi Fukuma
- Division of Electrical Engineering and Computer Science , Kanazawa University , Kakuma-machi, Kanazawa 920-1192 , Japan
- Nano Life Science Institute (WPI-NanoLSI) , Kakuma-machi, Kanazawa 920-1192 , Japan
| | - Ryugo Tero
- Department of Environmental and Life Sciences , Toyohashi University of Technology , Toyohashi , Aichi 441-8580 , Japan
| |
Collapse
|
13
|
Snead WT, Stachowiak JC. Structure Versus Stochasticity-The Role of Molecular Crowding and Intrinsic Disorder in Membrane Fission. J Mol Biol 2018; 430:2293-2308. [PMID: 29627460 DOI: 10.1016/j.jmb.2018.03.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 03/22/2018] [Accepted: 03/26/2018] [Indexed: 01/07/2023]
Abstract
Cellular membranes must undergo remodeling to facilitate critical functions including membrane trafficking, organelle biogenesis, and cell division. An essential step in membrane remodeling is membrane fission, in which an initially continuous membrane surface is divided into multiple, separate compartments. The established view has been that membrane fission requires proteins with conserved structural features such as helical scaffolds, hydrophobic insertions, and polymerized assemblies. In this review, we discuss these structure-based fission mechanisms and highlight recent findings from several groups that support an alternative, structure-independent mechanism of membrane fission. This mechanism relies on lateral collisions among crowded, membrane-bound proteins to generate sufficient steric pressure to drive membrane vesiculation. As a stochastic process, this mechanism contrasts with the paradigm that deterministic protein structures are required to drive fission, raising the prospect that many more proteins may participate in fission than previously thought. Paradoxically, our recent work suggests that intrinsically disordered domains may be among the most potent drivers of membrane fission, owing to their large hydrodynamic radii and substantial chain entropy. This stochastic view of fission also suggests new roles for the structure-based fission proteins. Specifically, we hypothesize that in addition to driving fission directly, the canonical fission machines may facilitate the enrichment and organization of bulky disordered protein domains in order to promote membrane fission by locally amplifying protein crowding.
Collapse
Affiliation(s)
- Wilton T Snead
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712, USA
| | - Jeanne C Stachowiak
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA.
| |
Collapse
|
14
|
Imam ZI, Kenyon LE, Ashby G, Nagib F, Mendicino M, Zhao C, Gadok AK, Stachowiak JC. Phase-Separated Liposomes Enhance the Efficiency of Macromolecular Delivery to the Cellular Cytoplasm. Cell Mol Bioeng 2017; 10:387-403. [PMID: 29104698 PMCID: PMC5665383 DOI: 10.1007/s12195-017-0489-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 05/11/2017] [Indexed: 11/28/2022] Open
Abstract
INTRODUCTION From viruses to organelles, fusion of biological membranes is used by diverse biological systems to deliver macromolecules across membrane barriers. Membrane fusion is also a potentially efficient mechanism for the delivery of macromolecular therapeutics to the cellular cytoplasm. However, a key shortcoming of existing fusogenic liposomal systems is that they are inefficient, requiring a high concentration of fusion-promoting lipids in order to cross cellular membrane barriers. OBJECTIVES Toward addressing this limitation, our experiments explore the extent to which membrane fusion can be amplified by using the process of lipid membrane phase separation to concentrate fusion-promoting lipids within distinct regions of the membrane surface. METHODS We used confocal fluorescence microscopy to investigate the integration of fusion-promoting lipids into a ternary lipid membrane system that separated into liquid-ordered and liquid-disordered membrane phases. Additionally, we quantified the impact of membrane phase separation on the efficiency with which liposomes transferred lipids and encapsulated macromolecules to cells, using a combination of confocal fluorescence imaging and flow cytometry. RESULTS Here we report that concentrating fusion-promoting lipids within phase-separated lipid domains on the surfaces of liposomes significantly increases the efficiency of liposome fusion with model membranes and cells. In particular, membrane phase separation enhanced the delivery of lipids and model macromolecules to the cytoplasm of tumor cells by at least 4-fold in comparison to homogenous liposomes. CONCLUSIONS Our findings demonstrate that phase separation can enhance membrane fusion by locally concentrating fusion-promoting lipids on the surface of liposomes. This work represents the first application of lipid membrane phase separation in the design of biomaterials-based delivery systems. Additionally, these results lay the ground work for developing fusogenic liposomes that are triggered by physical and molecular cues associated with target cells.
Collapse
Affiliation(s)
- Zachary I. Imam
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX USA
| | - Laura E. Kenyon
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX USA
| | - Grant Ashby
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX USA
| | - Fatema Nagib
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX USA
| | - Morgan Mendicino
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX USA
| | - Chi Zhao
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX USA
| | - Avinash K. Gadok
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX USA
| | - Jeanne C. Stachowiak
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX USA
| |
Collapse
|
15
|
Xia Y, Jang HS, Shen Z, Bothun GD, Li Y, Nieh MP. Effects of Membrane Defects and Polymer Hydrophobicity on Networking Kinetics of Vesicles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:5745-5751. [PMID: 28510460 DOI: 10.1021/acs.langmuir.7b00373] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The kinetics of clustering unilamellar vesicles induced by inverse Pluronics [poly(propylene oxide)m-poly(ethylene oxide)n-poly(propylene oxide)m, POm-EOn-POm] was investigated via experiments and molecular dynamic simulations. Two important factors for controlling the networking kinetics are the membrane defects, presumably located at the interfacial region between two lipid domains induced by acyl chain mismatch, and the polymer hydrophobicity. As expected, the clustering rate increases significantly with increasing bilayer defects on the membrane where the insertion of PPO is likely to take place because of the reduced energy barrier for the insertion of PO. The hydrophobic interaction between the PO blocks and membranes with the defects region dictates the "anchoring" kinetics, which is controlled by the association-dissociation of PO with the lipid membrane. As a result, the dependence of clustering rate on polymer concentration is strongly influenced by the hydrophobicity of the PO blocks. Nevertheless, longer PO blocks show stronger association with the membrane, resulting in faster consumption of the "active" sites made of these defect regions (causing mostly "invalid" insertions) with increasing polymer concentration, hence inhibiting the formation of large networking clusters, while shorter PO blocks undergo more frequent association with/dissociation from the defects, allowing continuous formation of larger clusters with increasing polymer concentration. This study provides important insights into how the organization and dynamics of a biomembrane influence its interaction with foreign amphiphilic molecules.
Collapse
Affiliation(s)
| | - Hyun-Sook Jang
- Center for Soft and Living Matter (CSLM), Institute for Basic Science (IBS) , Ulju-gun, Ulsan 689-798, Republic of Korea
| | | | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island , Kingston, Rhode Island 02881, United States
| | | | | |
Collapse
|