scholarly journals Ultrastructural Analysis of Human Epidermal CD44 Reveals Preferential Distribution on Plasma Membrane Domains Facing the Hyaluronan-rich Matrix Pouches

1998 ◽  
Vol 46 (2) ◽  
pp. 241-248 ◽  
Author(s):  
Anna-Liisa Tuhkanen ◽  
Markku Tammi ◽  
Alpo Pelttari ◽  
Ulla M. Ågren ◽  
Raija Tammi
Keyword(s):  
Plasma Membrane ◽  
Basement Membrane ◽  
Intercellular Space ◽  
Plasma Membranes ◽  
Ultrastructural Localization ◽  
Cell Types ◽  
Membrane Domains ◽  
Immunogold Staining ◽  
Plasma Membrane Domains ◽  
Plasma Membrane Domain

We used immunogold staining and stereology to examine the ultrastructural localization and to estimate the relative content of CD44 in different strata and cell types of normal human epidermis. We found that CD44 existed almost exclusively on the plasma membranes; only rare labeling occurred on vesicular structures within the cytoplasm. Quantitation of the immunogold particles indicated that the labeling density of melanocytes corresponded to that of basal keratinocytes, and Langerhans cells displayed a labeling density of ∼10% that of the surrounding spinous cells. Among keratinocyte strata, the highest labeling density occurred on spinous cells, suggesting upregulation of CD44 after detachment from the basement membrane. The plasma membrane distribution of CD44 was compartmentalized, with little signal on cell–cell and cell-substratum contact sites such as desmosomes, the plasma membrane domain facing the basement membrane, and the close apposition of terminally differentiating granular cells. In contrast, CD44 was abundant on plasma membrane domains facing an open intercellular space, rich in hyaluronan. This distribution is in line with a role of CD44 as a hyaluronan receptor, important in the maintenance of the intercellular space for nutritional and cell motility functions in stratified epithelia.

Membrane microdomains: lessons from microscopy

1995 ◽  
Vol 53 ◽  
pp. 776-777
Author(s):  
J.M. Robinson ◽  
J.M Oliver
Keyword(s):  
Spatial Distribution ◽  
Plasma Membrane ◽  
Epithelial Cells ◽  
Plasma Membranes ◽  
Cell Types ◽  
Imaging Modalities ◽  
Membrane Microdomains ◽  
Membrane Domains ◽  
Lateral Heterogeneity ◽  
Functional Importance

Specialized regions of plasma membranes displaying lateral heterogeneity are the focus of this Symposium. Specialized membrane domains are known for certain cell types such as differentiated epithelial cells where lateral heterogeneity in lipids and proteins exists between the apical and basolateral portions of the plasma membrane. Lateral heterogeneity and the presence of microdomains in membranes that are uniform in appearance have been more difficult to establish. Nonetheless a number of studies have provided evidence for membrane microdomains and indicated a functional importance for these structures.This symposium will focus on the use of various imaging modalities and related approaches to define membrane microdomains in a number of cell types. The importance of existing as well as emerging imaging technologies for use in the elucidation of membrane microdomains will be highlighted. The organization of membrane microdomains in terms of dimensions and spatial distribution is of considerable interest and will be addressed in this Symposium.

scholarly journals Involvement of Raft-Like Plasma Membrane Domains of Entamoeba histolytica in Pinocytosis and Adhesion

2004 ◽  
Vol 72 (9) ◽  
pp. 5349-5357 ◽  
Author(s):  
Richard C. Laughlin ◽  
Glen C. McGugan ◽  
Rhonda R. Powell ◽  
Brenda H. Welter ◽  
Lesly A. Temesvari
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Entamoeba Histolytica ◽  
Fluid Phase ◽  
Cell Types ◽  
Cysteine Proteases ◽  
Membrane Domains ◽  
Cell Surface Molecule ◽  
Physiological Relevance ◽  
Plasma Membrane Domains

ABSTRACT Lipid rafts are highly ordered, cholesterol-rich, and detergent-resistant microdomains found in the plasma membrane of many eukaryotic cells. These domains play important roles in endocytosis, secretion, and adhesion in a variety of cell types. The parasitic protozoan Entamoeba histolytica, the causative agent of amoebic dysentery, was determined to have raft-like plasma membrane domains by use of fluorescent lipid analogs that specifically partition into raft and nonraft regions of the membrane. Disruption of raft-like membrane domains in Entamoeba with the cholesterol-binding agents filipin and methyl-β-cyclodextrin resulted in the inhibition of several important virulence functions, fluid-phase pinocytosis, and adhesion to host cell monolayers. However, disruption of raft-like domains did not inhibit constitutive secretion of cysteine proteases, another important virulence function of Entamoeba. Flotation of the cold Triton X-100-insoluble portion of membranes on sucrose gradients revealed that the heavy, intermediate, and light subunits of the galactose-N-acetylgalactosamine-inhibitible lectin, an important cell surface adhesion molecule of Entamoeba, were enriched in cholesterol-rich (raft-like) fractions, whereas EhCP5, another cell surface molecule, was not enriched in these fractions. The subunits of the lectin were also observed in high-density, actin-rich fractions of the sucrose gradient. Together, these data suggest that pinocytosis and adhesion are raft-dependent functions in this pathogen. This is the first report describing the existence and physiological relevance of raft-like membrane domains in E. histolytica.

Protein trafficking and polarity in kidney epithelium: from cell biology to physiology

1996 ◽  
Vol 76 (1) ◽  
pp. 245-297 ◽  
Author(s):  
D. Brown ◽  
J. L. Stow
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Protein Trafficking ◽  
Cell Biology ◽  
Cell Types ◽  
Membrane Domains ◽  
Disease States ◽  
Target Membrane ◽  
Plasma Membrane Domains ◽  
Membrane Components

The transepithelial movement of fluids, electrolytes, and larger molecules is achieved by the activity of a host of specialized transporting proteins, including enzymes, receptors, and channels, that are located on either the apical, basal, or lateral plasma membrane domains of epithelial cells. In the kidney as well as in all other organs, this remarkable polarity of epithelial cells depends on the selective insertion of newly synthesized and recycling proteins and lipids into distinct plasma membrane domains and on the maintenance and modulation of these specialized domains once they are established during epithelial development. This review addresses the mechanisms by which epithelial cells control the movement of membrane components within the cell to ensure that they are delivered to the correct target membrane. Among the topics discussed are targeting signals within membrane proteins, the role of the cytoskeleton and the tight junctional barrier in cell polarity, and the requirement for accessory proteins in the targeting process, including GTP-binding proteins, and proteins that are involved in vesicle docking and fusion events. The final part of the review is devoted uniquely to the polarized targeting of functionally defined proteins in various kidney cell types. In concluding, examples of how a breakdown in these trafficking pathways may be related to some disease states are presented.

scholarly journals Distribution of G-proteins in rat liver plasma-membrane domains and endocytic pathways

1989 ◽  
Vol 261 (3) ◽  
pp. 905-912 ◽  
Author(s):  
N Ali ◽  
G Milligan ◽  
W H Evans
Keyword(s):  
Plasma Membrane ◽  
G Proteins ◽  
Rat Liver ◽  
Plasma Membranes ◽  
Alpha Subunit ◽  
Membrane Domains ◽  
Liver Plasma Membrane ◽  
Golgi Membranes ◽  
Late Endosomes ◽  
Plasma Membrane Domains

1. The distribution of the alpha- and beta-subunits of nucleotide-binding G-proteins among rat liver sinusoidal, lateral and canalicular plasma membranes, endosomes, Golgi membranes and lysosomes was investigated. 2. Pertussis-toxin-catalysed ADP-ribosylation identified a 41 kDa inhibitory alpha-subunit in all liver plasma-membrane functional domains as well as in endosomes. An antibody to a synthetic peptide corresponding to a C-terminal sequence of the inhibitory alpha-subunit also identified the 41 kDa polypeptide in all plasma-membrane domains, in ‘early’ and ‘late’ endosomes and in Golgi membranes; this polypeptide was not detected in lysosomes. The antibody-binding studies showed that bile-canalicular plasma membranes had the highest content of the inhibitory alpha-subunit. 3. Immunofluorescent microscopy confirmed the presence of the inhibitory alpha-subunit in all regions of the hepatocyte's cell surface. 4. An antibody recognizing the beta-subunit showed that a 36 kDa polypeptide was present in all plasma membranes and in ‘early’ and ‘late’ endosomes; it was not detected in lysosomes. The relative distribution among the fractions of this polypeptide was similar to the distribution of the inhibitory alpha-subunit. 5. The presence of high levels of the G-protein inhibitory alpha-subunit in bile-canalicular plasma membranes was confirmed by demonstration of its co-fractionation with marker enzymes in Nycodenz gradients and by free-flow electrophoresis. The significance of this location is discussed.

scholarly journals Rapid Nonvesicular Transport of Sterol between the Plasma Membrane Domains of Polarized Hepatic Cells

2002 ◽  
Vol 277 (33) ◽  
pp. 30325-30336
Author(s):  
Daniel Wüstner ◽  
Andreas Herrmann ◽  
Mingming Hao ◽  
Frederick R. Maxfield
Keyword(s):  
Plasma Membrane ◽  
Membrane Domains ◽  
Hepatic Cells ◽  
Plasma Membrane Domains

scholarly journals Fluorescent, short-chain C6-NBD-sphingomyelin, but not C6-NBD-glucosylceramide, is subject to extensive degradation in the plasma membrane: implications for signal transduction related to cell differentiation

1995 ◽  
Vol 309 (3) ◽  
pp. 905-912 ◽  
Author(s):  
J W Kok ◽  
T Babia ◽  
K Klappe ◽  
D Hoekstra
Keyword(s):  
Signal Transduction ◽  
Plasma Membrane ◽  
Cell Differentiation ◽  
Plasma Membranes ◽  
Cell Types ◽  
Short Chain ◽  
Synthetic Activity ◽  
Intact Cells ◽  
Ht29 Cells ◽  
Extensive Degradation

The involvement of the plasma membrane in the metabolism of the sphingolipids sphingomyelin (SM) and glucosylceramide (GlcCer) was studied, employing fluorescent short-chain analogues of these lipids, 6-[N-(7-nitro-2,1,3-benzoxadiazol-4-yl) amino]hexanoylsphingosylphosphorylcholine (C6-NBD-SM), C6-NBD-GlcCer and their common biosynthetic precursor C6-NBD-ceramide (C6-NBD-Cer). Although these fluorescent short-chain analogues are metabolically active, some caution is to be taken in view of potential changes in biophysical/biochemical properties of the lipid compared with its natural counterpart. However, these short-chain analogues offer the advantage of studying the lipid metabolic enzymes in their natural environment, since detergent solubilization is not necessary for measuring their activity. These studies were carried out with several cell types, including two phenotypes (differing in state of differentiation) of HT29 cells. Degradation and biosynthesis of C6-NBD-SM and C6-NBD-GlcCer were determined in intact cells, in their isolated plasma membranes, and in plasma membranes isolated from rat liver tissue. C6-NBD-SM was found to be subject to extensive degradation in the plasma membrane, due to neutral sphingomyelinase (N-SMase) activity. The extent of C6-NBD-SM hydrolysis showed a general cell-type dependence and turned out to be dependent on the state of cell differentiation, as revealed for HT29 cells. In undifferentiated HT29 cells N-SMase activity was at least threefold higher than in its differentiated counterpart. In contrast, in all cell types studied, very little if any biosynthesis of C6-NBD-SM from the precursor C6-NBD-Cer occurred. Moreover, in the case of C6-NBD-GlcCer, neither hydrolytic nor synthetic activity was found to be associated with the plasma membrane. These results are discussed in the context of the involvement of the sphingolipids SM and GlcCer in signal transduction pathways in the plasma membrane.

scholarly journals Synergistic Assembly of Linker for Activation of T Cells Signaling Protein Complexes in T Cell Plasma Membrane Domains

2003 ◽  
Vol 278 (22) ◽  
pp. 20389-20394 ◽  
Author(s):  
Lorian C. Hartgroves ◽  
Joseph Lin ◽  
Hanno Langen ◽  
Tobias Zech ◽  
Arthur Weiss ◽  
...  
Keyword(s):  
T Cells ◽  
Plasma Membrane ◽  
T Cell ◽  
Protein Complexes ◽  
Membrane Domains ◽  
Cell Plasma Membrane ◽  
Signaling Protein ◽  
Cell Plasma ◽  
Plasma Membrane Domains
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