Caveolin-1, galectin-3 and lipid raft domains in cancer cell signalling

Spatial organization of the plasma membrane is an essential feature of the cellular response to external stimuli. Receptor organization at the cell surface mediates transmission of extracellular stimuli to intracellular signalling molecules and effectors that impact various cellular processes including cell differentiation, metabolism, growth, migration and apoptosis. Membrane domains include morphologically distinct plasma membrane invaginations such as clathrin-coated pits and caveolae, but also less well-defined domains such as lipid rafts and the galectin lattice. In the present chapter, we will discuss interaction between caveolae, lipid rafts and the galectin lattice in the control of cancer cell signalling.

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Individual Palmitoyl Residues Serve Distinct Roles in H-Ras Trafficking, Microlocalization, and Signaling

Molecular and Cellular Biology ◽

10.1128/mcb.25.15.6722-6733.2005 ◽

2005 ◽

Vol 25 (15) ◽

pp. 6722-6733 ◽

Cited By ~ 142

Author(s):

Sandrine Roy ◽

Sarah Plowman ◽

Barak Rotblat ◽

Ian A. Prior ◽

Cornelia Muncke ◽

...

Keyword(s):

Plasma Membrane ◽

Golgi Apparatus ◽

Lipid Rafts ◽

Lipid Bilayer ◽

Spatial Organization ◽

Cysteine Residues ◽

Wild Type ◽

Membrane Affinity ◽

Lateral Segregation

ABSTRACT H-ras is anchored to the plasma membrane by two palmitoylated cysteine residues, Cys181 and Cys184, operating in concert with a C-terminal S-farnesyl cysteine carboxymethylester. Here we demonstrate that the two palmitates serve distinct biological roles. Monopalmitoylation of Cys181 is required and sufficient for efficient trafficking of H-ras to the plasma membrane, whereas monopalmitoylation of Cys184 does not permit efficient trafficking beyond the Golgi apparatus. However, once at the plasma membrane, monopalmitoylation of Cys184 supports correct GTP-regulated lateral segregation of H-ras between cholesterol-dependent and cholesterol-independent microdomains. In contrast, monopalmitoylation of Cys181 dramatically reverses H-ras lateral segregation, driving GTP-loaded H-ras into cholesterol-dependent microdomains. Intriguingly, the Cys181 monopalmitoylated H-ras anchor emulates the GTP-regulated microdomain interactions of N-ras. These results identify N-ras as the Ras isoform that normally signals from lipid rafts but also reveal that spacing between palmitate and prenyl groups influences anchor interactions with the lipid bilayer. This concept is further supported by the different plasma membrane affinities of the monopalmitoylated anchors: Cys181-palmitate is equivalent to the dually palmitoylated wild-type anchor, whereas Cys184-palmitate is weaker. Thus, membrane affinity of a palmitoylated anchor is a function both of the hydrophobicity of the lipid moieties and their spatial organization. Finally we show that the plasma membrane affinity of monopalmitoylated anchors is absolutely dependent on cholesterol, identifying a new role for cholesterol in promoting interactions with the raft and nonraft plasma membrane.

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Compartmentalization of the Exocyst Complex in Lipid Rafts Controls Glut4 Vesicle Tethering

Molecular Biology of the Cell ◽

10.1091/mbc.e06-01-0030 ◽

2006 ◽

Vol 17 (5) ◽

pp. 2303-2311 ◽

Cited By ~ 82

Author(s):

Mayumi Inoue ◽

Shian-Huey Chiang ◽

Louise Chang ◽

Xiao-Wei Chen ◽

Alan R. Saltiel

Keyword(s):

Plasma Membrane ◽

Glucose Uptake ◽

Lipid Rafts ◽

Lipid Raft ◽

Pdz Domain ◽

Vesicle Tethering ◽

Exocyst Complex ◽

Raft Domains ◽

Lipid Raft Microdomains ◽

Stimulation Of

Lipid raft microdomains act as organizing centers for signal transduction. We report here that the exocyst complex, consisting of Exo70, Sec6, and Sec8, regulates the compartmentalization of Glut4-containing vesicles at lipid raft domains in adipocytes. Exo70 is recruited by the G protein TC10 after activation by insulin and brings with it Sec6 and Sec8. Knockdowns of these proteins block insulin-stimulated glucose uptake. Moreover, their targeting to lipid rafts is required for glucose uptake and Glut4 docking at the plasma membrane. The assembly of this complex also requires the PDZ domain protein SAP97, a member of the MAGUKs family, which binds to Sec8 upon its translocation to the lipid raft. Exocyst assembly at lipid rafts sets up targeting sites for Glut4 vesicles, which transiently associate with these microdomains upon stimulation of cells with insulin. These results suggest that the TC10/exocyst complex/SAP97 axis plays an important role in the tethering of Glut4 vesicles to the plasma membrane in adipocytes.

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iTRVZ: liquid nano-platform for signal integration on the plasma membrane

10.1101/2021.12.30.474523 ◽

2021 ◽

Author(s):

Taka Aki Tsunoyama ◽

Christian Hoffmann ◽

Bo Tang ◽

Koichiro M Hirosawa ◽

Yuri L Nemoto ◽

...

Keyword(s):

Plasma Membrane ◽

Single Molecule ◽

Protein Interactions ◽

Tyrosine Kinases ◽

Focal Adhesions ◽

Specific Protein ◽

Signalling Pathways ◽

Signal Integration ◽

Signalling Molecules ◽

Raft Domains

Signalling is one of the most important functions of the cellular plasma membrane (PM). A variety of extracellular signalling molecules bind to their specific receptors in the PM, and the engaged receptors in turn trigger various cytoplasmic signalling cascades. These signalling pathways are intertwined and affect each other, in a process called crosstalk, which enables the cells to fine tune the overall signal. The crosstalk of different receptor signalling pathways has been examined quite extensively, but the platform responsible for signal integration has never been discovered. Here, using single-molecule imaging, we found a nanometer-scale (50-80 nm) liquid-like protein assembly on the PM cytoplasmic surface (at a density of ~2-μm apart from each other on average, with a lifetime of ~10 s), working as the signal transduction and integration platform for receptors, including GPI-anchored receptors (GPI-ARs), receptor-type tyrosine kinases (RTKs), and GPCRs. The platform consists of integrin, talin, RIAM, VASP, and zyxin, and is thus termed iTRVZ. These molecules are known as focal-adhesion constituents, but iTRVZ is distinct from focal adhesions, because iTRVZ exists on both the apical and basal PMs and lack vinculin. The iTRVZ formation is driven by specific protein-protein interactions, liquid-liquid phase separation, and interactions with actin filaments and raft domains via PI(4,5)P2. iTRVZ integrates and amplifies the GPI-AR and RTK signals in a strongly non-linear fashion, and thus works as an AND gate and noise filter. These findings greatly advance our understanding of the mechanism for crosstalk between signalling pathways.

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Signalling to the nucleus under the control of light and small molecules

Molecular BioSystems ◽

10.1039/c5mb00763a ◽

2016 ◽

Vol 12 (2) ◽

pp. 345-349 ◽

Cited By ~ 4

Author(s):

Samuel Juillot ◽

Hannes M. Beyer ◽

Josef Madl ◽

Wilfried Weber ◽

Matias D. Zurbriggen ◽

...

Keyword(s):

Plasma Membrane ◽

Small Molecules ◽

Regulatory Mechanism ◽

Cell Signalling ◽

Signalling Pathway ◽

Temporal Control ◽

Signalling Molecules ◽

Entire Cell ◽

Spatio Temporal ◽

Cell Signalling Pathway

One major regulatory mechanism in cell signalling is the spatio-temporal control of the localization of signalling molecules. We synthetically designed an entire cell signalling pathway, which allows controlling the transport of signalling molecules from the plasma membrane to the nucleus, by using light and small molecules.

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Lipid Rafts Are Triage Centers for Multimeric and Monomeric Thyrotropin Receptor Regulation

Endocrinology ◽

10.1210/en.2006-1580 ◽

2007 ◽

Vol 148 (7) ◽

pp. 3164-3175 ◽

Cited By ~ 22

Author(s):

R. Latif ◽

T. Ando ◽

T. F. Davies

Keyword(s):

Plasma Membrane ◽

G Protein ◽

Lipid Rafts ◽

Lipid Raft ◽

Significant Proportion ◽

Lipid Microdomains ◽

Biochemical Approach ◽

Biochemical Analyses ◽

Raft Domains ◽

G Protein Coupled

The TSH receptor (TSHR), a heptahelical G protein-coupled receptor on the surface of thyrocytes, is a major autoantigen and physiological regulator of the thyroid gland. Unlike other G protein-coupled receptors, the TSHR undergoes posttranslational cleavage of its ectodomain, leading to the existence of several forms of the receptor on the plasma membrane. We previously hypothesized that to achieve high fidelity and specificity of TSH ligand or TSHR autoantibody signaling, the TSHR may compartmentalize into microdomains within the plasma membrane. In support of this hypothesis we have shown previously that TSHRs reside in GM1 ganglioside-enriched lipid rafts in the plasma membrane of TSHR-expressing cells. In this study, we further explored the different forms of TSHRs that reside in lipid rafts. We studied both TSHR-transfected cells and rat thyrocytes, using both nondetergent biochemical analyses and receptor-lipid raft colocalization. Using the biochemical approach, we observed that monomeric receptors existed in both raft and nonraft fractions of the cell surface in the steady state. We also demonstrated that the multimeric forms of the receptor were preferentially partitioned into the lipid microdomains. Different TSHR forms, including multimers, were dynamically regulated both by receptor-specific and postreceptor-specific modulators. TSH ligand and TSHR antibody of the stimulating variety induced a decrease of multimeric forms in the raft fractions. In addition, multimeric and monomeric forms of the receptor were both associated with Gsα within and without the rafts. Although failure to achieve total lipid raft disruption prevented a conclusion regarding the relative power of TSHR signaling within and without the raft domains, these data showed clearly that not only were a significant proportion of TSHRs residing within lipid microdomains but that constitutive multimerization of TSHRs was actually regulated within the lipid rafts.

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Adaptive actin organization counteracts elevated membrane tension to ensure robust endocytosis

10.1101/2020.04.05.026559 ◽

2020 ◽

Author(s):

Charlotte Kaplan ◽

Sam J. Kenny ◽

Shirley Chen ◽

Johannes Schöneberg ◽

Ewa Sitarska ◽

...

Keyword(s):

Plasma Membrane ◽

Spatial Organization ◽

Force Generation ◽

List Type ◽

Membrane Tension ◽

Actin Assembly ◽

Actin Network ◽

Coated Pits ◽

Actin Organization ◽

Tightly Coupled

AbstractClathrin-mediated endocytosis (CME) remains robust despite variations in plasma membrane tension. Actin assembly-mediated force generation becomes essential for CME under high membrane tension, but the underlying mechanisms are not understood. We investigated actin network ultrastructure at each stage of CME by super-resolution imaging. Actin and N-WASP spatial organization indicate that polymerization initiates at the base of clathrin-coated pits and that the actin network then grows away from the plasma membrane. Actin network organization is not tightly coupled to endocytic clathrin coat growth and deformation. Membrane tension-dependent changes in actin organization explain this uncoupling. Under elevated membrane tension, CME dynamics slow down and the actin network grows higher, resulting in greater coverage of the clathrin coat. This adaptive mechanism is especially crucial during the initial membrane curvature-generating stages of CME. Our findings reveal that adaptive force generation by the actin network ensures robust CME progression despite changes in plasma membrane tension.Highlights-Clathrin coat surface area and actin ultra-structure adapt to elevated membrane tension.-The actin network is nucleated at the base of the clathrin-coated pit and grows upward.-Actin ultra-structural organization is not tightly coupled to CME progression.-Actin force generation is required earlier in CME progression under elevated membrane tension.SummaryKaplan et al. revealed that actin assembly compensates for changes in plasma membrane tension by an adaptive force generating mechanism to ensure robust endocytosis. Under elevated membrane tension the network grows deeper, even in early endocytic stages, from the base upward.

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Lattices, rafts, and scaffolds: domain regulation of receptor signaling at the plasma membrane

The Journal of Cell Biology ◽

10.1083/jcb.200811059 ◽

2009 ◽

Vol 185 (3) ◽

pp. 381-385 ◽

Cited By ~ 234

Author(s):

Patrick Lajoie ◽

Jacky G. Goetz ◽

James W. Dennis ◽

Ivan R. Nabi

Keyword(s):

Plasma Membrane ◽

Cell Surface ◽

Lipid Raft ◽

Scaffold Proteins ◽

Cell Junctions ◽

Cross Link ◽

Coated Pits ◽

Receptor Dynamics ◽

Raft Domains ◽

Molecular Lattices

The plasma membrane is organized into various subdomains of clustered macromolecules. Such domains include adhesive structures (cellular synapses, substrate adhesions, and cell–cell junctions) and membrane invaginations (clathrin-coated pits and caveolae), as well as less well-defined domains such as lipid rafts and lectin-glycoprotein lattices. Domains are organized by specialized scaffold proteins including the intramembranous caveolins, which stabilize lipid raft domains, and the galectins, a family of animal lectins that cross-link glycoproteins forming molecular lattices. We review evidence that these heterogeneous microdomains interact to regulate substratum adhesion and cytokine receptor dynamics at the cell surface.

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Changes Occur in Plasma Membrane Turnover when K562 Leukemia Cells are Induced to Differentiate

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100054042 ◽

1982 ◽

Vol 40 ◽

pp. 286-287

Author(s):

L. M. Marshall

Keyword(s):

Plasma Membrane ◽

Membrane Proteins ◽

Intracellular Transport ◽

Parent Cell ◽

Membrane Turnover ◽

Coated Pits ◽

Surface Distribution ◽

Specific Proteins ◽

Erythroleukemic Cell ◽

Specific Membrane

A human erythroleukemic cell line, metabolically blocked in a late stage of erythropoiesis, becomes capable of differentiation along the normal pathway when grown in the presence of hemin. This process is characterized by hemoglobin synthesis followed by rearrangement of the plasma membrane proteins and culminates in asymmetrical cytokinesis in the absence of nuclear division. A reticulocyte-like cell buds from the nucleus-containing parent cell after erythrocyte specific membrane proteins have been sequestered into its membrane. In this process the parent cell faces two obstacles. First, to organize its erythrocyte specific proteins at one pole of the cell for inclusion in the reticulocyte; second, to reduce or abolish membrane protein turnover since hemoglobin is virtually the only protein being synthesized at this stage. A means of achieving redistribution and cessation of turnover could involve movement of membrane proteins by a directional lipid flow. Generation of a lipid flow towards one pole and accumulation of erythrocyte-specific membrane proteins could be achieved by clathrin coated pits which are implicated in membrane endocytosis, intracellular transport and turnover. In non-differentiating cells, membrane proteins are turned over and are random in surface distribution. If, however, the erythrocyte specific proteins in differentiating cells were excluded from endocytosing coated pits, not only would their turnover cease, but they would also tend to drift towards and collect at the site of endocytosis. This hypothesis requires that different protein species are endocytosed by the coated vesicles in non-differentiating than by differentiating cells.

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