Maintenance of epithelial surface membrane lipid polarity: A role for differing phospholipid translocation rates

1986 ◽  
Vol 94 (1) ◽  
pp. 47-53 ◽  
Author(s):  
Bruce A. Molitoris ◽  
Francis R. Simon
Keyword(s):  
Surface Membrane ◽  
Membrane Lipid ◽  
Epithelial Surface

scholarly journals Functional diversity of isoprenoidal lipids in Methylobacterium extorquens PA1

2020 ◽  
Author(s):  
Sandra Rizk ◽  
Petra Henke ◽  
Carlos Santana-Molina ◽  
Gesa Martens ◽  
Marén Gnädig ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Surface Membrane ◽  
Chemical Properties ◽  
Carotenoid Biosynthesis ◽  
Membrane Lipid ◽  
Cellular Growth ◽  
Membrane Properties ◽  
Methylobacterium Extorquens ◽  
Ideal System ◽  
Eukaryotic Organisms

AbstractHopanoids and carotenoids are two of the major isoprenoid-derived lipid classes in prokaryotes that have been proposed to have similar membrane ordering properties as sterols. Methylobacterium extorquens contains hopanoids and carotenoids in their outer membrane, making them an ideal system to investigate whether isoprenoid lipids play a complementary role in outer membrane ordering and cellular fitness. By genetically knocking out hpnE, and crtB we disrupted the production of squalene, and phytoene in Methylobacterium extorquens PA1, which are the presumed precursors for hopanoids and carotenoids, respectively. Deletion of hpnE unexpectedly revealed that carotenoid biosynthesis utilizes squalene as a precursor resulting in a pigmentation with a C30 backbone, rather than the previously predicted C40 phytoene-derived pathway. We demonstrate that hopanoids but not carotenoids are essential for growth at high temperature. However, disruption of either carotenoid or hopanoid synthesis leads to opposing effects on outer membrane lipid packing. These observations show that hopanoids and carotenoids may serve complementary biophysical roles in the outer membrane. Phylogenetic analysis suggests that M. extorquens may have acquired the C30 pathway through lateral gene transfer with Planctomycetes. This suggests that the C30 carotenoid pathway may have provided an evolutionary advantage to M. extorquens.ImportanceAll cells have a membrane that delineates the boundary between life and its environment. To function properly, membranes must maintain a delicate balance of physical and chemical properties. Lipids play a crucial role in tuning membrane properties. In eukaryotic organisms from yeast to mammals, sterols are essential for assembling a cell surface membrane that can support life. However, bacteria generally do not make sterols, so how do they solve this problem? Hopanoids and carotenoids are two major bacterial lipids, that are proposed as sterol surrogates. In this study we explore the bacterium M. extorquens for studying the role of hopanoids and carotenoids in surface membrane properties and cellular growth. Our findings suggest that hopanoids and carotenoids may serve complementary roles balancing outer membrane properties, and provide a foundation for elucidating the principles of surface membrane adaptation.

Ischemia-induced loss of epithelial polarity: potential role of the actin cytoskeleton

1991 ◽  
Vol 260 (6) ◽  
pp. F769-F778 ◽  
Author(s):  
B. A. Molitoris
Keyword(s):  
Proximal Tubule ◽  
Membrane Lipids ◽  
Basolateral Membrane ◽  
Surface Membrane ◽  
Membrane Lipid ◽  
Epithelial Polarity ◽  
Membrane Domains ◽  
Cortical Actin ◽  
Proximal Tubule Cells ◽  
Tubule Cells

Proximal tubule cells play a major role in the reabsorption of ions, water, and solutes from the glomerular filtrate. This is accomplished, in large part, by a surface membrane polarized into structurally, biochemically, and physiologically distinct apical and basolateral membrane domains separated by cellular junctional complexes. Establishment and maintenance of these unique membrane domains is essential for the normal functioning of proximal tubular cells and is dependent on cortical actin cytoskeletal-surface membrane interactions. Ischemia results in the duration-dependent loss of apical and basolateral surface membrane lipid and protein polarity. This loss of surface membrane polarity is associated with disruption of the cortical actin microfilament network and the opening of cellular tight junctions. Surface membrane lipids and proteins are then free to diffuse laterally within the membrane bilayer into the alternate membrane domain. Functionally, ischemia-induced loss of epithelial polarity is, in part, responsible for reduced sodium and glucose reabsorption. With recovery, proximal tubule cells undergo remodeling of the surface membrane such that the unique apical and basolateral membrane domains are reestablished allowing normal cellular function to return.

scholarly journals New insights into the cell biology of ischemic acute renal failure.

1991 ◽  
Vol 1 (12) ◽  
pp. 1263-1270 ◽  
Author(s):  
B A Molitoris
Keyword(s):  
Proximal Tubule ◽  
Cell Biology ◽  
Membrane Lipids ◽  
Basolateral Membrane ◽  
Surface Membrane ◽  
Membrane Lipid ◽  
Membrane Domains ◽  
Proximal Tubule Cells ◽  
Glomerular Filtrate ◽  
Tubule Cells

Proximal tubule cells play an essential role in the reabsorption of ions, water, and solutes from the glomerular filtrate. This is accomplished, in large part, by having a surface membrane polarized into structurally, biochemically, and physiologically distinct apical and basolateral membrane domains separated by cellular junctional complexes. Establishment and maintenance of these unique membrane domains are essential for the normal functioning of the cell. Ischemia results in the duration-dependent loss of apical and basolateral surface membrane lipid and protein polarity. Loss of surface membrane polarity is preceded by disruption of the microfilament network and opening of cellular tight junctions. Surface membrane lipids and proteins are then free to diffuse laterally within the bilayer into the alternate membrane domain. Functionally, ischemia-induced loss of epithelial polarity has been shown to be responsible for reduced sodium and glucose reabsorption. Reduced Na+ reabsorption has been related to redistribution of Na+, K(+)-ATPase into the apical membrane. During recovery from ischemic injury, proximal tubule cells undergo remodeling of the surface membrane such that the unique apical and basolateral membrane domains are reestablished, allowing for the return of normal cellular function.

Lateral mobility of plasma membrane lipids in bull spermatozoa: heterogeneity between surface domains and rigidification following cell death

1997 ◽  
Vol 110 (9) ◽  
pp. 1041-1050 ◽  
Author(s):  
S. Ladha ◽  
P.S. James ◽  
D.C. Clark ◽  
E.A. Howes ◽  
R. Jones
Keyword(s):  
Cell Death ◽  
Plasma Membrane ◽  
Membrane Lipids ◽  
Surface Membrane ◽  
Fold Increase ◽  
Membrane Lipid ◽  
Differentiated Cells ◽  
Immobile Phase ◽  
Lipid Diffusion ◽  
Surface Domains

Compartmentalization of surface membrane antigens into discrete regions or domains is a characteristic feature of differentiated cells. In mammalian spermatozoa at least 5 surface domains are known, implying the presence of barriers or boundaries within the plasma membrane. Using the technique of fluorescence recovery after photobleaching (FRAP) to measure diffusibility of fluorescent lipid analogues 1,1′-dihexadecyl-3,3,3′3′-tetramethylindocarbocyanine (DiIC[16]) and 5-(N-octa-decanoyl) aminofluorescein (ODAF), we have investigated lipid topology and dynamics in the plasma membrane of ejaculated bull spermatozoa. Contrary to reports in the literature, we have found that DiIC(16) stains only dead or damaged spermatozoa whereas ODAF intercalates into the plasma membrane of both live and dead cells, each type showing a distinctive staining pattern. FRAP analysis with ODAF revealed that diffusion coefficients on live spermatozoa are significantly faster on the acrosome and postacrosome (29.3x10(−9) cm2/second) than on the midpiece and principal piece (11.8x10(−9) cm2/second). Recovery (R) is >90% in all domains. ODAF diffusion also shows regionalized temperature-sensitivity with a 4-fold increase over the sperm head and a 1.8-fold increase on the tail between 20 degrees C and 37 degrees C. Remarkably, dead or permeabilized spermatozoa rapidly develop a large immobile phase (R<25%) over the whole plasma membrane. This rigidification is temperature insensitive and irreversible suggesting major changes in the physical state of membrane lipids. It is concluded that lipid diffusion in the plasma membrane of live bull spermatozoa is rapid and varies significantly between surface domains. Following permeabilization or cell death, however, a large immobile phase develops indicating substantial changes in membrane lipid disposition.

Changes in the organization of the surface membrane upon transformation of cercariae to schistosomula of the helminth parasite Schistosoma mansoni

Parasitology ◽  
1988 ◽  
Vol 96 (1) ◽  
pp. 85-97 ◽  
Author(s):  
M. Foley ◽  
J. R. Kusel ◽  
P. B. Garland
Keyword(s):  
Schistosoma Mansoni ◽  
Crystalline Phase ◽  
Liquid Crystalline ◽  
Fluorescence Recovery After Photobleaching ◽  
Surface Membrane ◽  
Skin Penetration ◽  
Membrane Lipid ◽  
Lipid Phase ◽  
Entire Surface ◽  
Fluorescent Compound

SUMMARYMerocyanin 540 (Mc540) is a fluorescent compound which is thought to bind to membranes in which there are substantial amounts of lipid in the lipid-crystalline phase. It is shown here to be of value in detecting the transformation by both mechanical and skin-penetration methods of the cercaria to the schistosomulum. The cercaria does not appear to bind Mc540, but the schistosomulum, binds Mc540 initially, in its anterior region, and at later times over the entire surface. The suggestion that transformation involves changes in the surface membrane lipid phase from gel to liquid-crystalline phase is supported by fluorescence recovery after photobleaching results with 5-N-(octadecanoyl)-amino fluorescein, a lipophilic dye which appears to be immobile in the cercaria, but fully mobile in the 40 min schistosomulum.

Microviscosity in the surface membrane lipid layer of intact normal lymphocyte leukemic cells

FEBS Letters ◽  
1974 ◽  
Vol 38 (3) ◽  
pp. 268-270 ◽  
Author(s):  
Michael Inbar ◽  
Meir Shinitzky ◽  
Leo Sachs
Keyword(s):  
Surface Membrane ◽  
Membrane Lipid ◽  
Leukemic Cells ◽  
Normal Lymphocyte ◽  
Lipid Layer

Nonpolarized surface distribution and delivery of human CD7 in polarized MDCK cells

1993 ◽  
Vol 265 (4) ◽  
pp. C1069-C1079 ◽  
Author(s):  
C. Haller ◽  
S. L. Alper
Keyword(s):  
Membrane Proteins ◽  
Protein Targeting ◽  
Mdck Cells ◽  
Transmembrane Protein ◽  
Surface Membrane ◽  
Experimental System ◽  
Surface Polarity ◽  
Epithelial Surface ◽  
Surface Distribution

Madin-Darby canine kidney (MDCK) cells grown on permeable supports have served as the most common experimental system for in vitro studies of the generation and maintenance of epithelial surface polarity. Protein targeting to the apical and basolateral plasmalemmal domains of these and other polarized epithelia has been suggested to rely on targeting sequences. Two simple sorting models for MDCK cells have proposed active sorting to a single domain, with "default" movement to the other domain. Examples of both apical and basal sorting signals have been found to support each hypothesis, but the idea of a default pathway has remained in question. Indeed, all endogenous and heterologous wild-type proteins so far studied in MDCK cells achieve polarized distributions at steady state. It is not known whether these selected proteins are representative of all surface membrane proteins or represent only a subset. We report here the apparent absence of sorting by MDCK cells of the transmembrane protein of T-cells, CD7. CD7 is expressed at similar density in apical and basolateral membranes of MDCK cells as assessed by both immunocytological and biochemical criteria. Furthermore, CD7 appears to be directly sorted to both surfaces at similar rates and turns over at both surfaces at similar rates. The nonpolarized distribution of CD7 appears independent of its level of expression. CD7 may identify a "bulk-flow" default pathway for plasma membrane proteins expressed in polarized MDCK cells.

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