scholarly journals Domain architecture of the smooth-muscle plasma membrane: regulation by annexins

2005 ◽  
Vol 387 (2) ◽  
pp. 309-314 ◽  
Author(s):  
Annette DRAEGER ◽  
Susan WRAY ◽  
Eduard B. BABIYCHUK
Keyword(s):  
Smooth Muscle ◽  
Plasma Membrane ◽  
Membrane Lipids ◽  
Domain Architecture ◽  
Focal Adhesions ◽  
Membrane Lipid ◽  
Dependent Manner ◽  
Detailed Structural Analysis ◽  
Specific Subset ◽  
Associated Proteins

Individual signalling events are processed in distinct, spatially segregated domains of the plasma membrane. In a smooth muscle, the sarcolemma is divided into domains of focal adhesions alternating with caveolae-rich zones, both harbouring a specific subset of membrane-associated proteins. Recently, we have demonstrated that the sarcolemmal lipids are similarly segregated into domains of cholesterol-rich lipid rafts and glycerophospholipid-rich non-raft regions. In the present study, we provide a detailed structural analysis of the relationship between these proteinaceous and lipid domains. We demonstrate that the segregation of plasmalemmal protein constituents is intimately linked to that of the membrane lipids. Our results imply that lipid segregation is critical for the preservation of membrane protein architecture and essential for directional translocation of proteins to the sarcolemma. We show that the membrane lipid segregation is supported by the annexin protein family in a Ca2+-dependent manner. Eukaryotic cells harbour numerous, tissue-specific subsets of annexins. By examining the significance of this variety in a smooth muscle, we demonstrate that four different annexins target membrane sites of distinct lipid composition and that each annexin requires a different [Ca2+] for its translocation to the sarcolemma. Our results suggest that the interactions of annexins with distinct plasma membrane regions promote membrane segregation and, in combination with their individual Ca2+ sensitivity, might allow a spatially confined, graded response to a multitude of extra- or intracellular stimuli.

scholarly journals Defining how multiple lipid species interact with inward rectifier potassium (Kir2) channels

2020 ◽  
Vol 117 (14) ◽  
pp. 7803-7813 ◽  
Author(s):  
Anna L. Duncan ◽  
Robin A. Corey ◽  
Mark S. P. Sansom
Keyword(s):  
Plasma Membrane ◽  
Membrane Lipids ◽  
Membrane Lipid ◽  
Inward Rectifier ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Anionic Lipid ◽  
Lipid Interactions ◽  
Interaction Sites ◽  
Lipid Species

Protein–lipid interactions are a key element of the function of many integral membrane proteins. These potential interactions should be considered alongside the complexity and diversity of membrane lipid composition. Inward rectifier potassium channel (Kir) Kir2.2 has multiple interactions with plasma membrane lipids: Phosphatidylinositol (4, 5)-bisphosphate (PIP2) activates the channel; a secondary anionic lipid site has been identified, which augments the activation by PIP2; and cholesterol inhibits the channel. Molecular dynamics simulations are used to characterize in molecular detail the protein–lipid interactions of Kir2.2 in a model of the complex plasma membrane. Kir2.2 has been simulated with multiple, functionally important lipid species. From our simulations we show that PIP2interacts most tightly at the crystallographic interaction sites, outcompeting other lipid species at this site. Phosphatidylserine (PS) interacts at the previously identified secondary anionic lipid interaction site, in a PIP2concentration-dependent manner. There is interplay between these anionic lipids: PS interactions are diminished when PIP2is not present in the membrane, underlining the need to consider multiple lipid species when investigating protein–lipid interactions.

scholarly journals Impact of Membrane Lipids on UapA and AzgA Transporter Subcellular Localization and Activity in Aspergillus nidulans

2021 ◽  
Vol 7 (7) ◽  
pp. 514
Author(s):  
Mariangela Dionysopoulou ◽  
George Diallinas
Keyword(s):  
Plasma Membrane ◽  
Subcellular Localization ◽  
Aspergillus Nidulans ◽  
Membrane Lipids ◽  
Membrane Lipid ◽  
Lipid Biosynthesis ◽  
Transport Kinetics ◽  
Negative Effect ◽  
And Function

Recent biochemical and biophysical evidence have established that membrane lipids, namely phospholipids, sphingolipids and sterols, are critical for the function of eukaryotic plasma membrane transporters. Here, we study the effect of selected membrane lipid biosynthesis mutations and of the ergosterol-related antifungal itraconazole on the subcellular localization, stability and transport kinetics of two well-studied purine transporters, UapA and AzgA, in Aspergillus nidulans. We show that genetic reduction in biosynthesis of ergosterol, sphingolipids or phosphoinositides arrest A. nidulans growth after germling formation, but solely blocks in early steps of ergosterol (Erg11) or sphingolipid (BasA) synthesis have a negative effect on plasma membrane (PM) localization and stability of transporters before growth arrest. Surprisingly, the fraction of UapA or AzgA that reaches the PM in lipid biosynthesis mutants is shown to conserve normal apparent transport kinetics. We further show that turnover of UapA, which is the transporter mostly sensitive to membrane lipid content modification, occurs during its trafficking and by enhanced endocytosis, and is partly dependent on autophagy and Hect-type HulARsp5 ubiquitination. Our results point out that the role of specific membrane lipids on transporter biogenesis and function in vivo is complex, combinatorial and transporter-dependent.

Abstract 361: Cyclophilin A Mediates Angiotensin II--Stimulated NADPH Oxidase Activation in Vascular Smooth Muscle Cells

2012 ◽  
Vol 32 (suppl_1) ◽  
Author(s):  
Nwe Nwe Soe ◽  
Mark Sowden ◽  
Patrizia Nigro ◽  
Bradford C Berk
Keyword(s):  
Smooth Muscle ◽  
Plasma Membrane ◽  
Nadph Oxidase ◽  
Smooth Muscle Cells ◽  
Fold Increase ◽  
Muscle Cells ◽  
Dependent Manner ◽  
Ang Ii ◽  
Membrane Translocation ◽  
Ppiase Activity

Objective: Cyclophilin A (CyPA) is a ubiquitously expressed cytosolic protein that possesses PPIase activity and scaffold function. CyPA regulates Angiotensin II (Ang II) induced reactive oxygen species (ROS) production in vascular smooth muscle cells. However, the mechanism of this CyPA regulation remains unclear. We hypothesized that CyPA regulates plasma membrane translocation of NADPH oxidase cytosolic subunit, p47phox, which is required for NADPH oxidase structural organization and activity. Methods and results: Immunofluorescence studies in rat aortic smooth muscle cells revealed that CyPA translocated from the cytosol to the plasma membrane in response to Ang II in a time dependent manner with a peak at 10min (46.4±5.4 fold increase). Mouse Aortic Smooth Muscle Cells (MASM) were isolated from mice lacking CyPA (CyPA-/-) and wild type controls (WT), treated with Ang II (100nM) and immunofluorescence analysis was performed. Ang II induced p47phox plasma membrane translocation at 10min in WT mice. However, p47 phox translocation was significantly inhibited in CyPA -/- MASM. CyPA and p47phox colocalized at the plasma membrane in response to Ang II. Further analysis using subcellular fractionation studies confirmed that Ang II induced p47phox plasma membrane translocation was inhibited in CyPA -/- MASM compared to WT (1.2±2.7 vs 4.3±3.4 fold increase). Coimmunoprecipitation analyses confirmed that Ang II increased CyPA association with p47phox in a time dependent manner (2.5±3.4 fold increase at 10min). Finally, pretreatment with the PPIase activity inhibitor, cyclosporine A (1uM), could not inhibit CyPA association with p47phox and CyPA mediated p47phox translocation to the plasma membrane. Conclusion: These data suggest that Ang II promotes an association between CyPA and p47phox that enhances plasma membrane translocation of p47phox. This is proposed to increase the NADPH oxidase activity thereby increasing cellular ROS production. This process is independent of the PPIase activity of CyPA. Therefore, inhibition of the CyPA and p47phox association could be a future therapeutic target for Ang II induced ROS regulated cardiovascular diseases such as atherosclerosis and abdominal aortic aneurysm formation.

scholarly journals Homocysteine promotes vascular smooth muscle cell migration by induction of the adipokine resistin

2009 ◽  
Vol 297 (6) ◽  
pp. C1466-C1476 ◽  
Author(s):  
Changtao Jiang ◽  
Heng Zhang ◽  
Weizhen Zhang ◽  
Wei Kong ◽  
Yi Zhu ◽  
...  
Keyword(s):  
Cardiovascular Disease ◽  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cell ◽  
Muscle Cell ◽  
Vascular Smooth Muscle Cell ◽  
Focal Adhesions ◽  
Diabetic Patients ◽  
Dependent Manner ◽  
Concentration Dependent Manner

Adipokines may represent a mechanism linking insulin resistance to cardiovascular disease. We showed previously that homocysteine (Hcy), an independent risk factor for cardiovascular disease, can induce the expression and secretion of resistin, a novel adipokine, in vivo and in vitro. Since vascular smooth muscle cell (VSMC) migration is a key event in vascular disease, we hypothesized that adipocyte-derived resistin is involved in Hcy-induced VSMC migration. To confirm our hypothesis, Sprague-Dawley rat aortic SMCs were cocultured with Hcy-stimulated primary rat epididymal adipocytes or treated directly with increasing concentrations of resistin for up to 24 h. Migration of VSMCs was investigated. Cytoskeletal structure and cytoskeleton-related proteins were also detected. The results showed that Hcy (300–500 μM) increased migration significantly in VSMCs cocultured with adipocytes but not in VSMC cultured alone. Resistin alone also significantly increased VSMC migration in a time- and concentration-dependent manner. Resistin small interfering RNA (siRNA) significantly attenuated VSMC migration in the coculture system, which indicated that adipocyte-derived resistin mediates Hcy-induced VSMC migration. On cell spreading assay, resistin induced the formation of focal adhesions near the plasma membrane, which suggests cytoskeletal rearrangement via an α5β1-integrin-focal adhesion kinase/paxillin-Ras-related C3 botulinum toxin substrate 1 (Rac1) pathway. Our data demonstrate that Hcy promotes VSMC migration through a paracrine or endocrine effect of adipocyte-derived resistin, which provides further evidence of the adipose-vascular interaction in metabolic disorders. The migratory action exerted by resistin on VSMCs may account in part for the increased incidence of restenosis in diabetic patients.

scholarly journals Epidermal Growth Factor Receptor Activation Remodels the Plasma Membrane Lipid Environment To Induce Nanocluster Formation

2010 ◽  
Vol 30 (15) ◽  
pp. 3795-3804 ◽  
Author(s):  
Nicholas Ariotti ◽  
Hong Liang ◽  
Yufei Xu ◽  
Yueqiang Zhang ◽  
Yoshiya Yonekubo ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Molecular Mechanisms ◽  
Receptor Activation ◽  
Membrane Lipid ◽  
Dependent Manner ◽  
Epidermal Growth ◽  
Lipid Environment ◽  
Lateral Segregation

ABSTRACT Signal transduction is regulated by the lateral segregation of proteins into nanodomains on the plasma membrane. However, the molecular mechanisms that regulate the lateral segregation of cell surface receptors, such as receptor tyrosine kinases, upon ligand binding are unresolved. Here we used high-resolution spatial mapping to investigate the plasma membrane nanoscale organization of the epidermal growth factor (EGF) receptor (EGFR). Our data demonstrate that in serum-starved cells, the EGFR exists in preformed, cholesterol-dependent, actin-independent nanoclusters. Following stimulation with EGF, the number and size of EGFR nanoclusters increase in a time-dependent manner. Our data show that the formation of EGFR nanoclusters requires receptor tyrosine kinase activity. Critically, we show for the first time that production of phosphatidic acid by phospholipase D2 (PLD2) is essential for ligand-induced EGFR nanocluster formation. In accordance with its crucial role in regulating EGFR nanocluster formation, we demonstrate that modulating PLD2 activity tunes the degree of EGFR nanocluster formation and mitogen-activated protein kinase signal output. Together, these data show that EGFR activation drives the formation of signaling domains by regulating the production of critical second-messenger lipids and modifying the local membrane lipid environment.

scholarly journals Oligomerization and Ca2+/calmodulin control binding of the ER Ca2+-sensors STIM1 and STIM2 to plasma membrane lipids

2013 ◽  
Vol 33 (5) ◽  
Author(s):  
Rajesh Bhardwaj ◽  
Hans-Michael Müller ◽  
Walter Nickel ◽  
Matthias Seedorf
Keyword(s):  
Plasma Membrane ◽  
Membrane Lipids ◽  
Lipid Binding ◽  
Dependent Manner ◽  
Activation Threshold ◽  
Concentration Dependent Manner ◽  
Rich Domain ◽  
Α Helix ◽  
Distinct Features ◽  
Ca2 Channels

Ca2+ (calcium) homoeostasis and signalling rely on physical contacts between Ca2+ sensors in the ER (endoplasmic reticulum) and Ca2+ channels in the PM (plasma membrane). STIM1 (stromal interaction molecule 1) and STIM2 Ca2+ sensors oligomerize upon Ca2+ depletion in the ER lumen, contact phosphoinositides at the PM via their cytosolic lysine (K)-rich domains, and activate Ca2+ channels. Differential sensitivities of STIM1 and STIM2 towards ER luminal Ca2+ have been studied but responses towards elevated cytosolic Ca2+ concentration and the mechanism of lipid binding remain unclear. We found that tetramerization of the STIM1 K-rich domain is necessary for efficient binding to PI(4,5)P2-containing PM-like liposomes consistent with an oligomerization-driven STIM1 activation. In contrast, dimerization of STIM2 K-rich domain was sufficient for lipid binding. Furthermore, the K-rich domain of STIM2, but not of STIM1, forms an amphipathic α-helix. These distinct features of the STIM2 K-rich domain cause an increased affinity for PI(4,5)P2, consistent with the lower activation threshold of STIM2 and a function as regulator of basal Ca2+ levels. Concomitant with higher affinity for PM lipids, binding of CaM (calmodulin) inhibited the interaction of the STIM2 K-rich domain with liposomes in a Ca2+ and PI(4,5)P2 concentration-dependent manner. Therefore we suggest that elevated cytosolic Ca2+ concentration down-regulates STIM2-mediated ER–PM contacts via CaM binding.

scholarly journals Plasma Membrane Lipid Domains as Platforms for Vesicle Biogenesis and Shedding?

Biomolecules ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 94 ◽  
Author(s):  
Hélène Pollet ◽  
Louise Conrard ◽  
Anne-Sophie Cloos ◽  
Donatienne Tyteca
Keyword(s):  
Plasma Membrane ◽  
Membrane Lipids ◽  
Disease Diagnosis ◽  
Membrane Lipid ◽  
Lipid Domains ◽  
Disease Evolution ◽  
Physiological Processes ◽  
Plasma Membrane Lipid ◽  
Vesicle Biogenesis ◽  
Few Data

Extracellular vesicles (EVs) contribute to several pathophysiological processes and appear as emerging targets for disease diagnosis and therapy. However, successful translation from bench to bedside requires deeper understanding of EVs, in particular their diversity, composition, biogenesis and shedding mechanisms. In this review, we focus on plasma membrane-derived microvesicles (MVs), far less appreciated than exosomes. We integrate documented mechanisms involved in MV biogenesis and shedding, focusing on the red blood cell as a model. We then provide a perspective for the relevance of plasma membrane lipid composition and biophysical properties in microvesiculation on red blood cells but also platelets, immune and nervous cells as well as tumor cells. Although only a few data are available in this respect, most of them appear to converge to the idea that modulation of plasma membrane lipid content, transversal asymmetry and lateral heterogeneity in lipid domains may play a significant role in the vesiculation process. We suggest that lipid domains may represent platforms for inclusion/exclusion of membrane lipids and proteins into MVs and that MVs could originate from distinct domains during physiological processes and disease evolution.

The focal adhesions of chick retinal pigmented epithelial cells

1985 ◽  
Vol 63 (6) ◽  
pp. 553-563 ◽  
Author(s):  
Michał Opas
Keyword(s):  
Plasma Membrane ◽  
Incident Light ◽  
Focal Adhesions ◽  
Rpe Cells ◽  
Surface Reflection ◽  
Immersion Medium ◽  
Microfilament Bundles ◽  
Associated Proteins ◽  
Definition Of

Retinal pigmented epithelial (RPE) cells obtained from the eyes of chick embryos form colonies in vitro in which cells at the periphery of the colony express an undifferentiated, well-spread morphology and develop extremely large areas of cell–substratum adhesion. These adhesions can be classified as focal on the basis of the following: (a) their black surface reflection interference image, the contrast of which is not affected by changes in either the wavelength of the incident light or the refractive index of the immersion medium; (b) their association with the termini of actin-containing microfilament bundles; and (c) their ability to be labelled with antiserum against vinculin, a protein specific for adhesions of the focal type. The focal adhesions of RPE cells comprise laterally associated individual focal contacts, the mechanism by which this association is achieved and maintained is yet unknown. Because of the unusually large size and excellent microscopical definition of their focal adhesions, I used RPE cells to investigate the role of other actin-associated proteins in adhesion complexes. One of these, nonerythroid spectrin (fodrin), a protein suggested to play a role in anchoring actin filaments to the plasma membrane, was neither concentrated in nor excluded from the focal adhesions of RPE cells. Thus, at least in this cell type, spectrin seems unlikely to serve as a link between the major actin-containing microfilament bundles and the plasma membrane in the regions of cell-to-substratum contacts.

scholarly journals Pyk2- and Src-Dependent Tyrosine Phosphorylation of PDK1 Regulates Focal Adhesions

2003 ◽  
Vol 23 (22) ◽  
pp. 8019-8029 ◽  
Author(s):  
Yoshihiro Taniyama ◽  
David S. Weber ◽  
Petra Rocic ◽  
Lula Hilenski ◽  
Marjorie L. Akers ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Tyrosine Phosphorylation ◽  
Adhesion Formation ◽  
Focal Adhesions ◽  
Dependent Manner ◽  
Critical Function ◽  
Focal Adhesion Formation ◽  
Dependent Protein ◽  
And Migration

ABSTRACT 3-Phosphoinositide-dependent protein kinase 1 (PDK1) is a signal integrator that activates the AGC superfamily of serine/threonine kinases. PDK1 is phosphorylated on tyrosine by oxidants, although its regulation by agonists that stimulate G-protein-coupled receptor signaling pathways and the physiological consequences of tyrosine phosphorylation in this setting have not been fully identified. We found that angiotensin II stimulates the tyrosine phosphorylation of PDK1 in vascular smooth muscle in a calcium- and c-Src-dependent manner. The calcium-activated tyrosine kinase Pyk2 acts as a scaffold for Src-dependent phosphorylation of PDK1 on Tyr9, which permits phosphorylation of Tyr373 and -376 by Src. This critical function of Pyk2 is further supported by the observation that Pyk2 and tyrosine-phosphorylated PDK1 colocalize in focal adhesions after angiotensin II stimulation. Importantly, infection of smooth muscle cells with a Tyr9 mutant of PDK1 inhibits angiotensin II-induced tyrosine phosphorylation of paxillin and focal adhesion formation. These observations identify a novel interaction between PDK1 and Pyk2 that regulates the integrity of focal adhesions, which are major compartments for integrating signals for cell growth, apoptosis, and migration.

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