Ultrastructural Evidence of Differential Solubility in Triton X-100 of Endothelial Vesicles and Plasma Membrane

Moldovan, Nicanor I.; Heltianu, Constantina; Simiónescu, N; Simionescu, Maya

doi:10.1006/excr.1995.1233

Cited by 39 publications

(28 citation statements)

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“…Immunoelectron Microscopy-To assess CD4 localization at the cell plasma membrane of Triton-treated cells we followed a previously reported protocol with some modifications (35). Briefly, CD4 ϩ cells were isolated from peripheral lymphocytes using the IsoCell TM human CD4 Isolation Kit (Pierce) according to the manufacturer's instruction.…”

Section: Methodsmentioning

confidence: 99%

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Phorbol Ester-induced Disruption of the CD4-Lck Complex Occurs within a Detergent-resistant Microdomain of the Plasma Membrane

Parolini¹,

Topa²,

Sorice³

et al. 1999

Journal of Biological Chemistry

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Recent studies have highlighted the existence of discrete microdomains at the cell surface that are distinct from caveolae. The function of these microdomains remains unknown. However, recent evidence suggests that they may participate in a subset of transmembrane signaling events. In hematopoietic cells, these low density Triton-insoluble (LDTI) microdomains (also called caveolae-related domains) are dramatically enriched in signaling molecules, such as cell surface receptors (CD4 and CD55), Src family tyrosine kinases (Lyn, Lck, Hck, and Fyn), heterotrimeric G proteins, and gangliosides (GM 1 and GM 3 ). Human T lymphocytes have become a well established model system for studying the process of phorbol ester-induced down-regulation of CD4. Here, we present evidence that phorbol 12-myristate 13-acetate (PMA)-induced down-regulation of the cell surface pool of CD4 occurs within the LDTI microdomains of T cells. Localization of CD4 in LDTI microdomains was confirmed by immunoelectron microscopy. PMA-induced disruption of the CD4-Lck complex was rapid (within 5 min), and this disruption occurred within LDTI microdomains. Because PMA is an activator of protein kinase C (PKC), we next evaluated the possible roles of different PKC isoforms in this process. Our results indicate that PMA induced the rapid translocation of cytosolic PKCs to LDTI microdomains. We identified PKC␣ as the major isoform involved in this translocation event. Taken together, our results support the hypothesis that LDTI microdomains represent a functionally important plasma membrane compartment in T cells.

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Section: Methodsmentioning

confidence: 99%

“…In one such study, cells were first detergent extracted, fixed, and analyzed by standard transmission electron microscopy. These authors elegantly demonstrated that caveolae and caveolae-related domains exist in intact cells (35).…”

Section: Detergent-resistant Plasma Membrane Microdomains Are Presentmentioning

confidence: 99%

Phorbol Ester-induced Disruption of the CD4-Lck Complex Occurs within a Detergent-resistant Microdomain of the Plasma Membrane

Parolini¹,

Topa²,

Sorice³

et al. 1999

Journal of Biological Chemistry

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“…Due to their lipid composition, caveolae can be isolated on the basis of buoyant density on suitable gradients (216,232). The most commonly applied technique involves collecting those microdomains that are insoluble in 1% Triton X-100 at 0-4°C on 0-30% sucrose gradients (35,163).…”

Section: Lpp In Signaling Platformsmentioning

confidence: 99%

Pulmonary phosphatidic acid phosphatase and lipid phosphate phosphohydrolase

Nanjundan

Possmayer

2003

American Journal of Physiology-Lung Cellular and Molecular Phys

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The lung contains two distinct forms of phosphatidic acid phosphatase (PAP). PAP1 is a cytosolic enzyme that is activated through fatty acid-induced translocation to the endoplasmic reticulum, where it converts phosphatidic acid (PA) to diacylglycerol (DAG) for the biosynthesis of phospholipids and neutral lipids. PAP1 is Mg2+ dependent and sulfhydryl reagent sensitive. PAP2 is a six-transmembrane-domain integral protein localized to the plasma membrane. Because PAP2 degrades sphingosine-1-phosphate (S1P) and ceramide-1-phosphate in addition to PA and lyso-PA, it has been renamed lipid phosphate phosphohydrolase (LPP). LPP is Mg2+independent and sulfhydryl reagent insensitive. This review describes LPP isoforms found in the lung and their location in signaling platforms (rafts/caveolae). Pulmonary LPPs likely function in the phospholipase D pathway, thereby controlling surfactant secretion. Through lowering the levels of lyso-PA and S1P, which serve as agonists for endothelial differentiation gene receptors, LPPs regulate cell division, differentiation, apoptosis, and mobility. LPP activity could also influence transdifferentiation of alveolar type II to type I cells. It is considered likely that these lipid phosphohydrolases have critical roles in lung morphogenesis and in acute lung injury and repair.

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“…In contrast, caveolin-3 expression is essentially restricted to skeletal and smooth muscle cells, as well as cardiac myocytes (10)(11)(12)(13)(14)(15)(16)(17)(18). The direct interaction with caveolin-1 results in the inhibition of a number of signaling molecules, such as G-protein a subunit, Ras, nitric oxide synthase, protein kinase C, and protein kinase A (2,7,10,(16)(17)(18)(19)(20)(21)(22)(23)(24)(25). However, caveolin-1 has also been shown to stimulate the estrogen and insulin receptor signaling (26,27).…”

Section: Introductionmentioning

confidence: 99%

Oxidative Stress Induces Premature Senescence by Stimulating Caveolin-1 Gene Transcription through p38 Mitogen-Activated Protein Kinase/Sp1–Mediated Activation of Two GC-Rich Promoter Elements

et al. 2006

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Cellular senescence is believed to represent a natural tumor suppressor mechanism. We have previously shown that upregulation of caveolin-1 was required for oxidative stressinduced premature senescence in fibroblasts. However, the molecular mechanisms underlying caveolin-1 up-regulation in senescent cells remain unknown. Here, we show that subcytotoxic oxidative stress generated by hydrogen peroxide application promotes premature senescence and stimulates the activity of a (À1,296) caveolin-1 promoter reporter gene construct in fibroblasts. Functional deletion analysis mapped the oxidative stress response elements of the mouse caveolin-1 promoter to the sequences À244/À222 and À124/À101. The hydrogen peroxide-mediated activation of both Cav-1 (À244/ À222) and Cav-1 (À124/À101) was prevented by the antioxidant quercetin. Combination of electrophoretic mobility shift studies, chromatin immunoprecipitation analysis, Sp1 overexpression experiments, as well as promoter mutagenesis identifies enhanced Sp1 binding to two GC-boxes at À238/ À231 and À118/À106 as the core mechanism of oxidative stress-triggered caveolin-1 transactivation. In addition, signaling studies show p38 mitogen-activated protein kinase (MAPK) as the upstream regulator of Sp1-mediated activation of the caveolin-1 promoter following oxidative stress. Inhibition of p38 MAPK prevents the oxidant-induced Sp1-mediated up-regulation of caveolin-1 protein expression and development of premature senescence. Finally, we show that oxidative stress induces p38-mediated up-regulation of caveolin-1 and premature senescence in normal human mammary epithelial cells but not in MCF-7 breast cancer cells, which do not express caveolin-1 and undergo apoptosis. This study delineates for the first time the molecular mechanisms that modulate caveolin-1 gene transcription upon oxidative stress and brings new insights into the redox control of cellular senescence in both normal and cancer cells.

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Ultrastructural Evidence of Differential Solubility in Triton X-100 of Endothelial Vesicles and Plasma Membrane

Cited by 39 publications

References 0 publications

Phorbol Ester-induced Disruption of the CD4-Lck Complex Occurs within a Detergent-resistant Microdomain of the Plasma Membrane

Phorbol Ester-induced Disruption of the CD4-Lck Complex Occurs within a Detergent-resistant Microdomain of the Plasma Membrane

Pulmonary phosphatidic acid phosphatase and lipid phosphate phosphohydrolase

Oxidative Stress Induces Premature Senescence by Stimulating Caveolin-1 Gene Transcription through p38 Mitogen-Activated Protein Kinase/Sp1–Mediated Activation of Two GC-Rich Promoter Elements

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