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Small GTPases Apr 2017The plasma membrane is generally associated with underling actin cytoskeleton. When the plasma membrane detaches from actin filaments, it is expanded by the... (Review)
Review
The plasma membrane is generally associated with underling actin cytoskeleton. When the plasma membrane detaches from actin filaments, it is expanded by the intracellular pressure and the spherical membrane protrusion which lacks underlying actin cortex, termed bleb, is formed. Bleb is widely used for migration across species; however, the molecular mechanism underlying membrane blebbing remains largely unknown. Our recent study revealed that 2 small GTPases, Rnd3 and RhoA, are important regulators of membrane blebbing. In the expanding blebs, Rnd3 is recruited to the plasma membrane and inhibits RhoA activity by activating RhoGAP. On the other hand, RhoA is activated at the retracting membrane and removes Rnd3 from plasma membrane by the activity of ROCK (Rho-associated protein kinase). ROCK is also important for the rapid reassembly of actin cortex and retraction of membrane blebs by activating Ezrin. We propose that a Rnd3 and RhoA cycle underlies the core machinery of continuous membrane blebbing.
Topics: Actin Cytoskeleton; Animals; Cell Membrane; Humans; Monomeric GTP-Binding Proteins
PubMed: 27314434
DOI: 10.1080/21541248.2016.1199266 -
Current Opinion in Cell Biology Oct 2020The cell surface is a mechanobiological unit that encompasses the plasma membrane, its interacting proteins, and the complex underlying cytoskeleton. Recently, attention... (Review)
Review
The cell surface is a mechanobiological unit that encompasses the plasma membrane, its interacting proteins, and the complex underlying cytoskeleton. Recently, attention has been directed to the mechanics of the plasma membrane, and in particular membrane tension, which has been linked to diverse cellular processes such as cell migration and membrane trafficking. However, how tension across the plasma membrane is regulated and propagated is still not completely understood. Here, we review recent efforts to study the interplay between membrane tension and the cytoskeletal machinery and how they control cell form and function. We focus on factors that have been proposed to affect the propagation of membrane tension and as such could determine whether it can act as a global or local regulator of cell behavior. Finally, we discuss the limitations of the available tool kit as new approaches that reveal its dynamics in cells are needed to decipher how membrane tension regulates diverse cellular processes.
Topics: Animals; Biomechanical Phenomena; Biophysics; Cell Membrane; Cell Movement; Humans; Microtubules
PubMed: 32416466
DOI: 10.1016/j.ceb.2020.04.001 -
Biology of the Cell Aug 2021Deformability of the plasma membrane, the outermost surface of metazoan cells, allows cells to be dynamic, mobile and flexible. Factors that affect this deformability,... (Review)
Review
Deformability of the plasma membrane, the outermost surface of metazoan cells, allows cells to be dynamic, mobile and flexible. Factors that affect this deformability, such as tension on the membrane, can regulate a myriad of cellular functions, including membrane resealing, cell motility, polarisation, shape maintenance, membrane area control and endocytic vesicle trafficking. This review focuses on mechanoregulation of clathrin-mediated endocytosis (CME). We first delineate the origins of cell membrane tension and the factors that yield to its spatial and temporal fluctuations within cells. We then review the recent literature demonstrating that tension on the membrane is a fast-acting and reversible regulator of CME. Finally, we discuss tension-based regulation of endocytic clathrin coat formation during physiological processes.
Topics: Animals; Cell Membrane; Clathrin; Clathrin-Coated Vesicles; Endocytosis; Eukaryotic Cells; Exocytosis; Humans; Protein Transport; Transport Vesicles
PubMed: 33788963
DOI: 10.1111/boc.202000110 -
Biological & Pharmaceutical Bulletin Aug 2006Biological membranes are composed of lipid bilayers. Major lipid components of the eukaryotic plasma membrane include glycerophospholipids, sphingolipids, and... (Review)
Review
Biological membranes are composed of lipid bilayers. Major lipid components of the eukaryotic plasma membrane include glycerophospholipids, sphingolipids, and cholesterol. Lipids are irregularly distributed between the two leaflets, thus causing lipid asymmetry, or within the same leaflet, forming a lipid microdomain. Glycerophospholipids and sphingolipids both contribute to the lipid asymmetry, whereas cholesterol and sphingolipids form lipid microdomains. Maintenance of proper lipid asymmetry is required for the mechanical stability of the membrane and for vesicular transport. On the other hand, local or global changes in lipid asymmetry are important for cell cycle progression, apoptosis, and platelet coagulation. Three classes of lipid translocases, P-type ATPases, ABC transporters, and scramblases, are known to be involved in the regulation of lipid asymmetry. In this review, we describe the physiological and pathological functions of lipid asymmetry and the current knowledge of lipid translocases.
Topics: ATP-Binding Cassette Transporters; Adenosine Triphosphatases; Biological Transport; Cell Membrane; Eukaryotic Cells; Glycerophospholipids
PubMed: 16880601
DOI: 10.1248/bpb.29.1542 -
Plant Signaling & Behavior 2016Aluminum (Al) toxicity and phosphorus (P) deficiency are 2 major limiting factors for plant growth and crop production in acidic soils. Organic acids exuded from roots... (Review)
Review
Aluminum (Al) toxicity and phosphorus (P) deficiency are 2 major limiting factors for plant growth and crop production in acidic soils. Organic acids exuded from roots have been generally regarded as a major resistance mechanism to Al toxicity and P deficiency. The exudation of organic acids is mediated by membrane-localized OA transporters, such as ALMT (Al-activated malate transporter) and MATE (multidrug and toxic compound extrusion). Beside on up-regulation expression of organic acids transporter gene, transcriptional, translational and post-translational regulation of the plasma membrane H(+)-ATPase are also involved in organic acid release process under Al toxicity and P deficiency. This mini-review summarizes the current knowledge about this field of study on the role of the plasma membrane H(+)-ATPase in organic acid exudation under Al toxicity and P deficiency conditions.
Topics: Aluminum; Carboxylic Acids; Cell Membrane; Models, Biological; Phosphorus; Proton-Translocating ATPases
PubMed: 26713714
DOI: 10.1080/15592324.2015.1106660 -
International Journal of Molecular... Jul 2020The cell membrane is a complex and highly regulated system that is composed of lipid bilayer and proteins. One of the main functions of the cell membrane is the... (Review)
Review
The cell membrane is a complex and highly regulated system that is composed of lipid bilayer and proteins. One of the main functions of the cell membrane is the regulation of cell entry. Cell-penetrating peptides (CPPs) are defined as peptides that can cross the plasma membrane and deliver their cargo inside the cell. The uptake of a peptide is determined by its sequence and biophysicochemical properties. At the same time, the uptake mechanism and efficiency are shown to be dependent on local peptide concentration, cell membrane lipid composition, characteristics of the cargo, and experimental methodology, suggesting that a highly efficient CPP in one system might not be as productive in another. To better understand the dependence of CPPs on the experimental system, we present a review of the in vitro assays that have been employed in the literature to evaluate CPPs and CPP-cargos. Our comprehensive review suggests that utilization of orthogonal assays will be more effective for deciphering the true ability of CPPs to translocate through the membrane and enter the cell cytoplasm.
Topics: Animals; Cell Membrane; Cell Membrane Permeability; Cell-Penetrating Peptides; Drug Delivery Systems; Endocytosis; Humans; Lipid Bilayers; Membrane Lipids; Protein Transport
PubMed: 32630650
DOI: 10.3390/ijms21134719 -
Proceedings of the National Academy of... Oct 2021Recent work has highlighted roles for thermodynamic phase behavior in diverse cellular processes. Proteins and nucleic acids can phase separate into three-dimensional...
Recent work has highlighted roles for thermodynamic phase behavior in diverse cellular processes. Proteins and nucleic acids can phase separate into three-dimensional liquid droplets in the cytoplasm and nucleus and the plasma membrane of animal cells appears tuned close to a two-dimensional liquid-liquid critical point. In some examples, cytoplasmic proteins aggregate at plasma membrane domains, forming structures such as the postsynaptic density and diverse signaling clusters. Here we examine the physics of these surface densities, employing minimal simulations of polymers prone to phase separation coupled to an Ising membrane surface in conjunction with a complementary Landau theory. We argue that these surface densities are a phase reminiscent of prewetting, in which a molecularly thin three-dimensional liquid forms on a usually solid surface. However, in surface densities the solid surface is replaced by a membrane with an independent propensity to phase separate. We show that proximity to criticality in the membrane dramatically increases the parameter regime in which a prewetting-like transition occurs, leading to a broad region where coexisting surface phases can form even when a bulk phase is unstable. Our simulations naturally exhibit three-surface phase coexistence even though both the membrane and the polymer bulk only display two-phase coexistence on their own. We argue that the physics of these surface densities may be shared with diverse functional structures seen in eukaryotic cells.
Topics: Animals; Cell Membrane; Cytoplasm; Polymers; Post-Synaptic Density; Proteins; Thermodynamics
PubMed: 34599097
DOI: 10.1073/pnas.2103401118 -
Protein Science : a Publication of the... Jun 2020Our understanding of the plasma membrane structure has undergone a major change since the proposal of the fluid mosaic model of Singer and Nicholson in the 1970s. In... (Review)
Review
Our understanding of the plasma membrane structure has undergone a major change since the proposal of the fluid mosaic model of Singer and Nicholson in the 1970s. In this model, the membrane, composed of over thousand lipid and protein species, is organized as a well-equilibrated two-dimensional fluid. Here, the distribution of lipids is largely expected to reflect a multicomponent system, and proteins are expected to be surrounded by an annulus of specialized lipid species. With the recognition that a multicomponent lipid membrane is capable of phase segregation, the membrane is expected to appear as patchwork quilt pattern of membrane domains. However, the constituents of a living membrane are far from being well equilibrated. The living cell membrane actively maintains a trans-bilayer asymmetry of composition, and its constituents are subject to a number of dynamic processes due to synthesis, lipid transfer as well as membrane traffic and turnover. Moreover, membrane constituents engage with the dynamic cytoskeleton of a living cell, and are both passively as well as actively manipulated by this engagement. The extracellular matrix and associated elements also interact with membrane proteins contributing to another layer of interaction. At the nano- and mesoscale, the organization of lipids and proteins emerge from these encounters, as well as from protein-protein, protein-lipid, and lipid-lipid interactions in the membrane. New methods to study the organization of membrane components at these scales have also been developed, and provide an opportunity to synthesize a new picture of the living cell surface as an active membrane composite.
Topics: Animals; Cell Membrane; Humans; Lipids; Membrane Lipids
PubMed: 32297381
DOI: 10.1002/pro.3874 -
Biochemical Society Transactions Aug 2021Lipid enveloped viruses contain a lipid bilayer coat that protects their genome to help facilitate entry into the new host cell. This lipid bilayer comes from the host... (Review)
Review
Lipid enveloped viruses contain a lipid bilayer coat that protects their genome to help facilitate entry into the new host cell. This lipid bilayer comes from the host cell which they infect. After viral replication, the mature virion hijacks the host cell plasma membrane where it is then released to infect new cells. This process is facilitated by the interaction between phospholipids that make up the plasma membrane and specialized viral matrix proteins. This step in the viral lifecycle may represent a viable therapeutic strategy for small molecules that aim to block enveloped virus spread. In this review, we summarize the current knowledge on the role of plasma membrane lipid-protein interactions on viral assembly and budding.
Topics: Cell Membrane; Host-Pathogen Interactions; Lipids; Proteins; Virus Assembly
PubMed: 34431495
DOI: 10.1042/BST20200854 -
Journal of Microbiology (Seoul, Korea) Mar 2016Candida albicans is a human fungal pathogen capable of causing lethal systemic infections. The plasma membrane plays key roles in virulence because it not only functions... (Review)
Review
Candida albicans is a human fungal pathogen capable of causing lethal systemic infections. The plasma membrane plays key roles in virulence because it not only functions as a protective barrier, it also mediates dynamic functions including secretion of virulence factors, cell wall synthesis, invasive hyphal morphogenesis, endocytosis, and nutrient uptake. Consistent with this functional complexity, the plasma membrane is composed of a wide array of lipids and proteins. These components are organized into distinct domains that will be the topic of this review. Some of the plasma membrane domains that will be described are known to act as scaffolds or barriers to diffusion, such as MCC/eisosomes, septins, and sites of contact with the endoplasmic reticulum. Other zones mediate dynamic processes, including secretion, endocytosis, and a special region at hyphal tips that facilitates rapid growth. The highly organized architecture of the plasma membrane facilitates the coordination of diverse functions and promotes the pathogenesis of C. albicans.
Topics: Candida albicans; Candidiasis; Cell Membrane; Endocytosis; Fungal Proteins; Humans; Hyphae; Models, Molecular; Virulence; Virulence Factors
PubMed: 26920878
DOI: 10.1007/s12275-016-5621-y