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Caveolae are tiny invaginations in the sarcolemma that buffer extra membrane and contribute to mechanical regulation of cellular function. While the role of caveolae in membrane mechanosensation has been studied predominantly in non-cardiomyocyte cells, caveolae contribution to cardiac mechanotransduction remains elusive. Here, we studied the role of caveolae in the regulation of Ca2+ signaling in atrial cardiomyocytes. In Langendorff-perfused mouse hearts, atrial pressure/volume overload stretched atrial myocytes and decreased caveolae density. In isolated cells, caveolae were disrupted through hypotonic challenge that induced a temporal (

Introduction: Rafts are protein-lipid structural nanodomains involved in efficient signal transduction and the modulation of physiological processes of the cell plasma membrane. Raft disruption in the nervous system has been associated with a wide range of disorders. Development: We review the concept of rafts, the nervous system processes in which they are involved, and their role in diseases such as Parkinson’s disease, Alzheimer disease, and Huntington disease. Conclusions: Based on the available evidence, preservation and/or reconstitution of rafts is a promising treatment strategy for a wide range of neurological disorders. Resumen: Introducción: Los rafts constituyen nanodominios estructurales de naturaleza lipo-proteica que propician la eficiente transducción de señales y la modulación de procesos fisiológicos asociados a la membrana plasmática. En el sistema nervioso, la alteración de estos dominios se ha asociado con el desarrollo de diversos padecimientos. Desarrollo: En el presente artículo se revisa el concepto de rafts, los procesos del sistema nervioso en los cuales están involucrados y su papel en distintas afectaciones, entre las que se destacan las enfermedades de Parkinson, Alzheimer y Huntington. Conclusiones: Dadas las evidencias de su participación en diversas neuropatías, la preservación y/o reconstitución de los rafts se vislumbran como una atractiva estrategia terapéutica.

Caveolae are tiny invaginations in the sarcolemma that buffer extra membrane and contribute to mechanical regulation of cellular function. While the role of caveolae in membrane mechanosensation has been studied predominantly in non-cardiomyocyte cells, caveolae contribution to cardiac mechanotransduction remains elusive. Here, we studied the role of caveolae in the regulation of Ca2+ signaling in atrial cardiomyocytes. In Langendorff-perfused mouse hearts, atrial pressure/volume overload stretched atrial myocytes and decreased caveolae density. In isolated cells, caveolae were disrupted through hypotonic challenge that induced a temporal (<10 min) augmentation of Ca2+ transients and caused a rise in Ca2+ spark activity. Similar changes in Ca2+ signaling were observed after chemical (methyl-β-cyclodextrin) and genetic ablation of caveolae in cardiac-specific conditional caveolin-3 knock-out mice. Acute disruption of caveolae, both mechanical and chemical, led to the elevation of cAMP level in the cell interior, and cAMP-mediated augmentation of protein kinase A (PKA)-phosphorylated ryanodine receptors (at Ser2030 and Ser2808). Caveolae-mediated stimulatory effects on Ca2+ signaling were abolished via inhibition of cAMP production by adenyl cyclase antagonists MDL12330 and SQ22536, or reduction of PKA activity by H-89. A compartmentalized mathematical model of mouse atrial myocytes linked the observed changes to a microdomain-specific decrease in phosphodiesterase activity, which disrupted cAMP signaling and augmented PKA activity. Our findings add a new dimension to cardiac mechanobiology and highlight caveolae-associated cAMP/PKA-mediated phosphorylation of Ca2+ handling proteins as a novel component of mechano-chemical feedback in atrial myocytes. [Display omitted] • Caveolae are an important but poorly understood component of membrane mechanosensing complex in cardiomyocytes. • Stretching of atrial myocytes flattens caveolae and increases membrane tension. • Caveolae disruption results in augmented Ca2+ signaling via cAMP-mediated increase in PKA-phosphorylated ryanodine receptors. • Computational modeling linked observed changes in Ca2+ signaling to a loss of caveolae-confined control of phosphodiesterases. • Caveolae-associated changes in Ca2+ signaling is a novel part of mechano-chemical feedback in atrial myocytes. [ABSTRACT FROM AUTHOR]

Abstract Background It has been reported that dietary fats and genetic factors in individuals are associated with the pattern of fat distribution. This study aimed to evaluate the interaction between dietary fats intake and Caveolin1 (CAV-1) rs 3807s992 polymorphism with fat distribution in overweight and obese women. Methods A total of 221 participants were included in the current cross-sectional study. Body composition, biochemical parameters were evaluated by body composition analyzer and Pars Azmoon kits and genotypes determination was performed by PCR–RFLP, dietary fats were measured using a validated semi-quantitative food frequency questionnaire (FAQ). Results The frequency of GG, AA and AG genotypes were 53.1, 24.6, and 22.3%, respectively, and the mean intake of total dietary fat intake was 97.47 ± 36.87 g. There was positive significant interaction between total fat intake and AA genotype on visceral fat level (p = 0.001), trunk fat (p = 0.01) and waist circumference (p = 0.05), positive significant interaction between total fat intake and AG genotype on the waist to hip ratio (WHR) (p = 0.02) and visceral fat level (p = 0.05), positive borderline significant interaction between saturated fatty acid and AA genotype on the trunk fat (p = 0.06), and between trans-fatty acids and AG genotype on WHR (p = 0.04), visceral fat level (p = 0.01), and between monounsaturated fatty acid and AG genotype on WHR (p = 0.04), and a borderline interaction between polyunsaturated fatty acid and AA genotypes on visceral fat level (p = 0.06), negative significant interaction between AG genotypes and linolenic acid on WHR (p = 0.04), borderline significant interaction between ALA and AG genotype on WHR (p = 0.06). Conclusions Our findings showed that CAV-1 rs 3807992 polymorphism and dietary fats were associated with fat distributions in individuals.

Background: It has been reported that dietary fats and genetic factors in individuals are associated with the pattern of fat distribution. This study aimed to evaluate the interaction between dietary fats intake and Caveolin1 (CAV-1) rs 3807s992 polymorphism with fat distribution in overweight and obese women. Methods: A total of 221 participants were included in the current cross-sectional study. Body composition, biochemical parameters were evaluated by body composition analyzer and Pars Azmoon kits and genotypes determination was performed by PCR–RFLP, dietary fats were measured using a validated semi-quantitative food frequency questionnaire (FAQ). Results: The frequency of GG, AA and AG genotypes were 53.1, 24.6, and 22.3%, respectively, and the mean intake of total dietary fat intake was 97.47 ± 36.87 g. There was positive significant interaction between total fat intake and AA genotype on visceral fat level (p = 0.001), trunk fat (p = 0.01) and waist circumference (p = 0.05), positive significant interaction between total fat intake and AG genotype on the waist to hip ratio (WHR) (p = 0.02) and visceral fat level (p = 0.05), positive borderline significant interaction between saturated fatty acid and AA genotype on the trunk fat (p = 0.06), and between trans-fatty acids and AG genotype on WHR (p = 0.04), visceral fat level (p = 0.01), and between monounsaturated fatty acid and AG genotype on WHR (p = 0.04), and a borderline interaction between polyunsaturated fatty acid and AA genotypes on visceral fat level (p = 0.06), negative significant interaction between AG genotypes and linolenic acid on WHR (p = 0.04), borderline significant interaction between ALA and AG genotype on WHR (p = 0.06). Conclusions: Our findings showed that CAV-1 rs 3807992 polymorphism and dietary fats were associated with fat distributions in individuals. [ABSTRACT FROM AUTHOR]

The plasma membrane in eukaryotic cells contains microdomains that are enriched in certain glycosphingolipids, gangliosides, and sterols (such as cholesterol) to form membrane/lipid rafts (MLR). These regions exist as caveolae, morphologically observable flask-like invaginations, or as a less easily detectable planar form. MLR are scaffolds for many molecular entities, including signaling receptors and ion channels that communicate extracellular stimuli to the intracellular milieu. Much evidence indicates that this organization and/or the clustering of MLR into more active signaling platforms depends upon interactions with and dynamic rearrangement of the cytoskeleton. Several cytoskeletal components and binding partners, as well as enzymes that regulate the cytoskeleton, localize to MLR and help regulate lateral diffusion of membrane proteins and lipids in response to extracellular events (e.g., receptor activation, shear stress, electrical conductance, and nutrient demand). MLR regulate cellular polarity, adherence to the extracellular matrix, signaling events (including ones that affect growth and migration), and are sites of cellular entry of certain pathogens, toxins and nanoparticles. The dynamic interaction between MLR and the underlying cytoskeleton thus regulates many facets of the function of eukaryotic cells and their adaptation to changing environments. Here, we review general features of MLR and caveolae and their role in several aspects of cellular function, including polarity of endothelial and epithelial cells, cell migration, mechanotransduction, lymphocyte activation, neuronal growth and signaling, and a variety of disease settings. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé.

Background/Aims: To test whether the physiological regulation of the cardiac Kv4 channels by the Ca2+/calmodulin-dependent protein kinase II (CaMKII) is restricted to lipid rafts and whether the interactions observed in rat cardiomyocytes also occur in the human ventricle. Methods: Ventricular myocytes were freshly isolated from Sprague-Dawley rats. Ito was recorded by the whole-cell Patch-Clamp technique. Membrane rafts were isolated by centrifugation in a discontinuous sucrose density gradient. The presence of the proteins of interest was analysed by western blot. Immunogold staining and electron microscopy of heart vibrosections was performed to localize Kv4.2/Kv4.3 and CaMKII proteins. Protein-protein interactions were determined by co-immunoprecipitation experiments in rat and human ventricular mycoytes. Results: Patch-Clamp recordings in control conditions and after lipid raft or caveolae disruption show that the CaMKII-Kv4 channel complex must associate in noncaveolar lipid rafts to be functional. Separation in density gradients, co-immunoprecipitation and electron microscopy show that there are two Kv4 channel populations: one located in caveolae, that is CaMKII independent, and another one located in planar membrane rafts, which is bound to CaMKII. Conclusion: CaMKII regulates only the Kv4 channel population located in non-caveolar lipid rafts. Thus, the regulation of cardiac Kv4 channels in rat and human ventricle depends on their subcellular localization. [ABSTRACT FROM AUTHOR]

Quiescin/sulfhydryl oxidase (QSOX1) is a secreted flavoprotein that modulates cellular proliferation, migration and adhesion, roles attributed to its ability to organize the extracellular matrix. We previously showed that exogenously added QSOX1b induces smooth muscle cells migration in a process that depends on its enzymatic activity and that is mediated by hydrogen peroxide derived from Nox1, a catalytic subunit of NAD(P)H oxidases. Here, we report that exogenous QSOX1b also stimulates the migration of L929 fibroblasts and that this effect is regulated by its endocytosis. The use of endocytosis inhibitors and caveolin 1-knockdown demonstrated that this endocytic pathway is caveola-mediated. QSOX1b colocalized with Nox1 in intracellular vesicles, as detected by confocal fluorescence, suggesting that extracellular QSOX1b is endocytosed with the transmembrane Nox1. These results reveal that endosomal QSOX1b is a novel intracellular redox regulator of cell migration. [Display omitted] • QSOX1b induces fibroblast migration. • Caveolae-dependent endocytosis contributes to QSOX1b uptake. • QSOX1b endocytosis is required for QSOX1b-promoted cell migration. • Endocytosed QSOX1b colocalizes with Nox1. • Nox1 is required to QSOX1b-induced migration. [ABSTRACT FROM AUTHOR]

Key points: Mutations in the caveolae scaffolding protein, caveolin‐3 (Cav3), have been linked to the long QT type 9 inherited arrhythmia syndrome (LQT9) and the cause of underlying action potential duration prolongation is incompletely understood.In the present study, we show that LQT9 Cav3 mutations, F97C and S141R, cause mutation‐specific gain of function effects on Cav1.2‐encoded L‐type Ca2+ channels responsible for ICa,L and also cause loss of function effects on heterologously expressed Kv4.2 and Kv4.3 channels responsible for Ito.A computational model of the human ventricular myocyte action potential suggests that the major ionic current change causing action potential duration prolongation in the presence of Cav3‐F97C is the slowly inactivating ICa,L but, for Cav3‐S141R, both increased ICa,L and increased late Na+ current contribute equally to action potential duration prolongation.Overall, the LQT9 Cav3‐F97C and Cav3‐S141R mutations differentially impact multiple ionic currents, highlighting the complexity of Cav3 regulation of cardiac excitability and suggesting mutation‐specific therapeutic approaches. Mutations in the CAV3 gene encoding caveolin‐3 (Cav3), a scaffolding protein integral to caveolae in cardiomyocytes, have been associated with the congenital long‐QT syndrome (LQT9). Initial studies demonstrated that LQT9‐associated Cav3 mutations, F97C and S141R, increase late sodium current as a potential mechanism to prolong action potential duration (APD) and cause LQT9. Whether these Cav3 LQT9 mutations impact other caveolae related ion channels remains unknown. We used the whole‐cell, patch clamp technique to characterize the effect of Cav3‐F97C and Cav3‐S141R mutations on heterologously expressed Cav1.2+Cavβ2cN4 channels, as well as Kv4.2 and Kv4.3 channels, in HEK 293 cells. Expression of Cav3‐S141R increased ICa,L density without changes in gating properties, whereas expression of Cav3‐F97C reduced Ca2+‐dependent inactivation of ICa,L without changing current density. The Cav3‐F97C mutation reduced current density and altered the kinetics of IKv4.2 and IKv4.3 and also slowed recovery from inactivation. Cav3‐S141R decreased current density and also slowed activation kinetics and recovery from inactivation of IKv4.2 but had no effect on IKv4.3. Using the O'Hara–Rudy computational model of the human ventricular myocyte action potential, the Cav3 mutation‐induced changes in Ito are predicted to have negligible effect on APD, whereas blunted Ca2+‐dependent inactivation of ICa,L by Cav3‐F97C is predicted to be primarily responsible for APD prolongation, although increased ICa,L and late INa by Cav3‐S141R contribute equally to APD prolongation. Thus, LQT9 Cav3‐associated mutations, F97C and S141R, produce mutation‐specific changes in multiple ionic currents leading to different primary causes of APD prolongation, which suggests the use of mutation‐specific therapeutic approaches in the future. Key points: Mutations in the caveolae scaffolding protein, caveolin‐3 (Cav3), have been linked to the long QT type 9 inherited arrhythmia syndrome (LQT9) and the cause of underlying action potential duration prolongation is incompletely understood.In the present study, we show that LQT9 Cav3 mutations, F97C and S141R, cause mutation‐specific gain of function effects on Cav1.2‐encoded L‐type Ca2+ channels responsible for ICa,L and also cause loss of function effects on heterologously expressed Kv4.2 and Kv4.3 channels responsible for Ito.A computational model of the human ventricular myocyte action potential suggests that the major ionic current change causing action potential duration prolongation in the presence of Cav3‐F97C is the slowly inactivating ICa,L but, for Cav3‐S141R, both increased ICa,L and increased late Na+ current contribute equally to action potential duration prolongation.Overall, the LQT9 Cav3‐F97C and Cav3‐S141R mutations differentially impact multiple ionic currents, highlighting the complexity of Cav3 regulation of cardiac excitability and suggesting mutation‐specific therapeutic approaches. [ABSTRACT FROM AUTHOR]

Copyright of Hungarian Medical Journal / Orvosi Hetilap is the property of Akademiai Kiado and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In biology, the modern scientific fashion is to mostly study proteins. Much less attention is paid to lipids. However, lipids themselves are extremely important for the formation and functioning of cellular membrane organelles. Here, the role of the geometry of the lipid bilayer in regulation of organelle shape is analyzed. It is proposed that during rapid shape transition, the number of lipid heads and their size (i.e., due to the change in lipid head charge) inside lipid leaflets modulates the geometrical properties of organelles, in particular their membrane curvature. Insertion of proteins into a lipid bilayer and the shape of protein trans-membrane domains also affect the trans-membrane asymmetry between surface areas of luminal and cytosol leaflets of the membrane. In the cases where lipid molecules with a specific shape are not predominant, the shape of lipids (cylindrical, conical, or wedge-like) is less important for the regulation of membrane curvature, due to the flexibility of their acyl chains and their high ability to diffuse.

RESUMO:A utilização da transgenia com a proteína fluorescente verde (GFP) como marcador de células de origem fetal nas placentas de clones bovinos servirá de modelo inédito para estudo morfofisiológico e imunológico da interação materno-fetal, visto que possibilitará o seu mapeamento, diferenciando as células fetais das maternas. Tal modelo terá aplicação direta, principalmente porque estes são animais que apresentam problemas em relação ao seu desenvolvimento. Com o auxílio deste modelo, pretende-se verificar o transporte de substâncias entre a mãe e o feto via endocitose, pela imunolocalização das proteínas chamadas de caveolinas. Para tanto foram utilizados 06 bovinos clonados e 30 bovinos de inseminação artificial (IA) com idade até 90 dias de gestação, os quais tiveram seu desenvolvimento interrompido mediante abate humanitário das receptoras e ovariosalpingohisterectomia, com posterior recuperação do útero gestante. Foram coletados os placentônios e o cório. Uma parte das amostras foi recortada e fixada, por imersão, em solução de parafolmaldeído a 4% ou formoldeído a 10% em tampão fosfato de sódio (PBS) a 0,1M pH 7.4, solução de Zamboni (4% de paraformoldeído, 15% de ácido pícrico, em tampão fosfato de sódio a 0,1M pH 7.4), metacarn (60% de metanol, 30% de clorofórmio, e 10% de ácido acético glacial), para verificação da morfologia e realização de imuno-histoquímica para as proteínas caveolinas -1 e -2 (CAV -1 e CAV-2). As caveolinas -1 foram localizadas nos vilos fetais e maternos, mas sua marcação mais forte foi observada no estroma endometrial. As caveolinas -2 tiveram marcação positiva no trofoblasto e membrana córioalantoide, e, especificamente em célula trofoblástica gigante binucleada. Sendo assim, os resultados mostram que a proteína CAV-1 teve uma maior expressão em relação à proteína CAV-2 e que as proteínas CAV-1 e -2 são parte da composição das cavéolas, sendo estruturas importantes e relacionadas com a transferência de moléculas para o feto, realizando a nutrição do mesmo mediante endocitose e pinocitose.

Introduction: Rafts are protein-lipid structural nanodomains involved in efficient signal transduction and the modulation of physiological processes of the cell plasma membrane. Raft disruption in the nervous system has been associated with a wide range of disorders., Development: We review the concept of rafts, the nervous system processes in which they are involved, and their role in diseases such as Parkinson's disease, Alzheimer disease, and Huntington disease., Conclusions: Based on the available evidence, preservation and/or reconstitution of rafts is a promising treatment strategy for a wide range of neurological disorders., (Copyright © 2021 Sociedad Española de Neurología. Published by Elsevier España, S.L.U. All rights reserved.)

Membrane lipid rafts are distinct plasma membrane nanodomains that are enriched with cholesterol, sphingolipids and gangliosides, with occasional presence of saturated fatty acids and phospholipids containing saturated acyl chains. It is well known that they organize receptors (such as Epithelial Growth Factor Receptor), ion channels and their downstream acting molecules to regulate intracellular signaling pathways. Among them are Ca 2 + signaling pathways, which are modified in tumor cells and inhibited upon membrane raft disruption. In addition to protein components, lipids from rafts also contribute to the organization and function of Ca 2 + signaling microdomains. This article aims to focus on the lipid raft KCa/ClCa/Ca 2 + channel complexes that regulate Ca 2 + and EGFR signaling in cancer cells, and discusses the potential modification of these complexes by lipids as a novel therapeutic approach in tumor development. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers. [ABSTRACT FROM AUTHOR]

We previously showed that intraperitoneal administration of Freund's adjuvant treatment resulted in acute peritonitis and TGF-β was found to be one of the main organizers of the subsequent EMT in mesothelial cells. In the present study, we investigated whether TGF-β signaling molecules are present in mesothelial cells and how their compartmentalization pattern changes with the dynamics of inflammatory events in vivo . In addition, we tried to evaluate the turnover of endosomal compartments concomitant with the internalization of signaling molecules and examine whether caveola-mediated internalization might play a role in the termination of TGF-β signaling. Using immunocytochemical approach, we could detect TβRII in EEA1 positive compartments and as the inflammation progressed, at D3, the receptor appeared in caveolin-1 positive intracellular structures as well. The latter event was accompanied by the appearance of negative regulatory protein, Smad7 in caveolae. We also found EEA1 and caveolin-1 double positive vesicular structures that were corresponded to forming MVBs affirmed by our immuno-electron microscopical results. Fine structural, morphometric and immunoblot analysis proved that Cd63 positive multivesicular body (MVB) formation was significantly increased by D3 and the IP results confirmed that TβRII as well as caveolin-1 were strongly associated with these endosomal compartments at this time. In contrast, by the termination of inflammation, by D5, caveolin-1 was found to be associated with late endosomal marker, Rab7 and entirely degraded from the system. Despite the limitations of an in vivo system, our results provide both morphological and biochemical data about the endosomal compartments involved in the internalization of TβRII upon inflammatory stimuli. Furthermore, our study implies the possible role of caveola-mediated endocytosis in the attenuation of TGF-β signaling and highlight the significance of endosomal compartments via which caveolae might meet the classical endocytic pathway under in vivo inflammatory conditions. [ABSTRACT FROM AUTHOR]

Copyright of Pesquisa Veterinaria Brasileira is the property of Colegio Brasileiro de Patologia Animal - CBPA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Caveolae are curved lipid raft regions rich in cholesterol and sphingolipids found abundantly in vascular endothelial cells, adipocytes, smooth muscle cells and fibroblasts. They are multifunctional organelles with roles in clathrin-independent endocytosis, cholesterol transport, mechanosensing and signal transduction. Caveolae provide an environmentwhere multiple receptor signalling components are sequestered, clustered and compartmentalized for efficient signal transduction. Many of these receptors, including cytokine signal transducer gp130 (glycoprotein 130), are mediators of chronic inflammation during atherogenesis. Subsequently, disruption of these organelles is associated with a broad range of disease states including cardiovascular disease and cancer. Cavin-1 is an essential peripheral component of caveolae that stabilizes caveolin-1, the main structural/integral membrane protein of caveolae. Caveolin-1 is an essential regulator of eNOS (endothelial nitric oxide synthase) and its disruption leads to endothelial dysfunction which initiates a range of cardiovascular and pulmonary disorders. Although dysfunctional cytokine signalling is also a hallmark of cardiovascular disease, knowledge of caveolae-dependent cytokine signalling is lacking as is the role of cavin-1 independent of caveolae. The present review introduces caveolae, their structural components, the caveolins and cavins, their regulation by cAMP, and their potential role in cardiovascular disease. [ABSTRACT FROM AUTHOR]

The actions of catecholamines on adrenergic receptors (ARs) induce sympathetic responses, and sustained activation of the sympathetic nervous system results in disrupted circulatory homeostasis. In cardiomyocytes, α1-ARs localize to flask-shaped membrane microdomains known as "caveolae." Caveolae require both caveolin and cavin proteins for their biogenesis and function. However, the functional roles and molecular interactions of caveolar components in cardiomyocytes are poorly understood. Here, we showed that muscle-restricted coiled-coil protein (MURC)/Cavin-4 regulated a1-AR-induced cardiomyocyte hypertrophy through enhancement of ERK1/2 activation in caveolae. MURC/Cavin-4 was expressed in the caveolae and T tubules of cardiomyocytes. MURC/Cavin-4 overexpression distended the caveolae, whereas MURC/Cavin-4 was not essential for their formation. MURC/Cavin-4 deficiency attenuated cardiac hypertrophy induced by a1-AR stimulation in the presence of caveolae. Interestingly, MURC/Cavin-4 bound to α1A- and α1B-ARs as well as ERK1/2 in caveolae, and spatiotemporally modulated MEK/ERK signaling in response to a1-AR stimulation. Thus, MURC/Cavin-4 facilitates ERK1/2 recruitment to caveolae and efficient α1-AR signaling mediated by caveolae in cardiomyocytes, which provides a unique insight into the molecular mechanisms underlying caveola-mediated signaling in cardiac hypertrophy. [ABSTRACT FROM AUTHOR]

Abstract: The plasma membrane in eukaryotic cells contains microdomains that are enriched in certain glycosphingolipids, gangliosides, and sterols (such as cholesterol) to form membrane/lipid rafts (MLR). These regions exist as caveolae, morphologically observable flask-like invaginations, or as a less easily detectable planar form. MLR are scaffolds for many molecular entities, including signaling receptors and ion channels that communicate extracellular stimuli to the intracellular milieu. Much evidence indicates that this organization and/or the clustering of MLR into more active signaling platforms depends upon interactions with and dynamic rearrangement of the cytoskeleton. Several cytoskeletal components and binding partners, as well as enzymes that regulate the cytoskeleton, localize to MLR and help regulate lateral diffusion of membrane proteins and lipids in response to extracellular events (e.g., receptor activation, shear stress, electrical conductance, and nutrient demand). MLR regulate cellular polarity, adherence to the extracellular matrix, signaling events (including ones that affect growth and migration), and are sites of cellular entry of certain pathogens, toxins and nanoparticles. The dynamic interaction between MLR and the underlying cytoskeleton thus regulates many facets of the function of eukaryotic cells and their adaptation to changing environments. Here, we review general features of MLR and caveolae and their role in several aspects of cellular function, including polarity of endothelial and epithelial cells, cell migration, mechanotransduction, lymphocyte activation, neuronal growth and signaling, and a variety of disease settings. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé. [Copyright &y& Elsevier]

Ca 2+ -activated Cl - (Cl Ca ) channels regulate membrane excitability and myogenic tone in vascular smooth muscles. TMEM16A-coding proteins are mainly responsible for functional Cl Ca channels in vascular smooth muscles, including portal vein smooth muscles (PVSMs). Caveolae are cholesterol-rich and Ω-shaped invaginations on the plasma membrane that structurally contributes to effective signal transduction. Caveolin 1 (Cav1) accumulates in caveolae to form functional complexes among receptors, ion channels, and kinases. The present study examined the functional roles of Cav1 in the expression and activity of Cl Ca channels in the portal vein smooth muscle cells (PVSMCs) of wild-type (WT) and Cav1-knockout (KO) mice. Contractile experiments revealed that the amplitude of spontaneous PVSM contractions was larger in Cav1-KO mice than WT mice. Under whole-cell patch-clamp configurations, Cl Ca currents were markedly inhibited by 1 µM Ani9 (a selective TMEM16A Cl Ca channel blocker) in WT and Cav1-KO PVSMCs. However, Ani9-sensitive Cl Ca currents were significantly larger in Cav1-KO PVSMCs than in WT PVSMCs. Expression analyses showed that TMEM16A expression levels were higher in Cav1-KO PVSMs than in WT PVSMs. Therefore, the caveolar structure formed by Cav1 negatively regulates the expression and activity of TMEM16A-mediated Cl Ca channels in vascular smooth muscle cells.

Abstract: How dietary fatty acids are absorbed into the enterocyte and transported to the ER is not established. We tested the possibility that caveolin-1 containing lipid rafts and endocytic vesicles were involved. Apical brush border membranes took up 15% of albumin bound 3H-oleate whereas brush border membranes from caveolin-1 KO mice took up only 1%. In brush border membranes, the 3H-oleate was in the detergent resistant fraction of an OptiPrep gradient. On OptiPrep gradients of intestinal cytosol, we also found the 3H-oleate in the detergent resistant fraction, separate from OptiPrep gradients spiked with 3H-oleate or 3H-triacylglycerol. Caveolin-1 immuno-depletion of cytosol removed 91% of absorbed 3H-oleate whereas immuno-depletion using IgG, or anti-caveolin-2 or -3 or anti-clathrin antibodies removed 20%. Electron microscopy showed the presence of caveolin-1 containing vesicles in WT mouse cytosol that were 4 fold increased by feeding intestinal sacs 1mM oleate. No vesicles were seen in caveolin-1 KO mouse cytosol. Caveolin-1 KO mice gained less weight on a 23% fat diet and had increased fat in their stool compared to WT mice. We conclude that dietary fatty acids are absorbed by caveolae in enterocyte brush border membranes, are endocytosed, and transported in cytosol in caveolin-1 containing endocytic vesicles. [Copyright &y& Elsevier]

TFPI (tissue factor pathway inhibitor) is an anticoagulant protein that prevents intravascular coagulation through inhibition of fXa (Factor Xa) and the TF (tissue factor)-fVIIa (Factor VIIa) complex. Localization of TFPI within caveolae enhances its anticoagulant activity. To define further how caveolae contribute to TFPI anticoagulant activity, CHO (Chinese-hamster ovary) cells were co-transfected with TF and membraneassociated TFPI targeted to either caveolae [TFPI-GPI (TFPI- glycosylphosphatidylinositol anchor chimaera)] or to bulk plasma membrane [TFPI-TM (TFPI-transmembrane anchor chimaera)]. Stable clones had equal expression of surface TF and TFPI. TX-114 cellular lysis confirmed localization of TFPI-GPI to detergent-insoluble membrane fractions, whereas TFPI-TM localized to the aqueous phase. TFPI-GPI and TFPI-TM were equally effective direct inhibitors of fXa in amidolytic assays. However, TFPI-GPI was a significantly better inhibitor of TF- fVIIa than TFPI-TM, as measured in both amidolytic and plasmaclotting assays. Disrupting caveolae by removing membrane cholesterol from EA.hy926 cells, which make TFPIα, CHO cells transfected with TFPIβ and HUVECs (human umbilical vein endothelial cells) did not affect their fXa inhibition, but significantly decreased their inhibition of TF-fVIIa. These studies confirm and quantify the enhanced anticoagulant activity of TFPI localized within caveolae, demonstrate that caveolae enhance the inhibitory activity of both TFPI isoforms and define the effect of caveolae as specifically enhancing the anti-TF activity of TFPI. [ABSTRACT FROM AUTHOR]

Abstract: Adenosine receptors are a member of the large family of seven transmembrane spanning G protein coupled receptors. The four adenosine receptor subtypes—A1, A2a, A2b, A3—exert their effects via the activation of one or more heterotrimeric G proteins resulting in the modulation of intracellular signaling. Numerous studies over the past decade have documented the complexity of G protein coupled receptor signaling at the level of protein–protein interactions as well as through signaling cross talk. With respect to adenosine receptors, the activation of one receptor subtype can have profound direct effects in one cell type but little or no effect in other cells. There is significant evidence that the compartmentation of subcellular signaling plays a physiological role in the fidelity of G protein coupled receptor signaling. This compartmentation is evident at the level of the plasma membrane in the form of membrane microdomains such as caveolae and lipid rafts. This review will summarize and critically assess our current understanding of the role of membrane microdomains in regulating adenosine receptor signaling. This article is part of a Special Issue entitled: “Adenosine Receptors”. [Copyright &y& Elsevier]

The endothelium can evoke relaxations (dilatations) of the underlying vascular smooth muscle, by releasing vasodilator substances. The best characterized endothelium-derived relaxing factor is nitric oxide (NO), which is synthesized by the endothelial isoform of nitric oxide synthase (eNOS). Endothelium-dependent relaxations involve both pertussis-toxin-sensitive Gi (e.g., responses to serotonin, sphingosine 1-phosphate, alpha2-adrenergic agonists, and thrombin) and pertussis-toxin-insensitive Gq (e.g., adenosine diphosphate and bradykinin) coupling proteins. eNOS undergoes a complex pattern of intracellular regulation, including post-translational modifications involving enzyme acylation and phosphorylation. eNOS is reversibly targeted to signal-transducing plasmalemmal caveolae where the enzyme interacts with a number of regulatory proteins, many of which are modified in cardiovascular disease states. The release of nitric oxide by the endothelial cell can be up- (e.g., by estrogens, exercise, and dietary factors) and down-regulated (e.g. oxidative stress, smoking, and oxidized low-density lipoproteins). It is reduced in the course of vascular disease (e.g., diabetes and hypertension). Arteries covered with regenerated endothelium (e.g. following angioplasty) selectively lose the pertussis-toxin-sensitive pathway for NO release which favors vasospasm, thrombosis, penetration of macrophages, cellular growth, and the inflammatory reaction leading to atherosclerosis. The unraveling of the complex interaction of the pathways regulating the presence and the activity of eNOS will enhance the understanding of the perturbations in endothelium-dependent signaling that are seen in cardiovascular disease states, and may lead to the identification of novel targets for therapeutic intervention. [ABSTRACT FROM AUTHOR]

Abstract: Membrane rafts and caveolae are specialized microdomains of the cell membrane that form physical platforms for compartmentalization of signalling molecules. Here, we intended to gain insight into the consequences of caveolar localization in G protein-coupled receptor function. We analysed β2-adrenoceptor signalling in purified CRLDF (caveolin-rich low density fractions) of β2-adrenoceptor-overexpressing HEK-293 cells. β2-adrenoceptor and Gs immunoreactivities and forskolin-stimulated adenylate cyclase activity were all detected in CRLDF obtained by the conventional raft purification method that uses Triton X-100 solubilization. However, Triton X-100 caused a complete loss of the functional coupling between β2-adrenoceptor, Gs and adenylate cyclase. Therefore, we developed an optimized purification method based on n-octyl-β-d-glucopyranoside solubilization, where the functional properties of β2-adrenoceptor, Gs and adenylate cyclase were preserved in the CRLDF. Using this method, we showed that isoproterenol-stimulated adenylate cyclase activity was similar in CRLDF and bulk membrane preparations of HEK-293 cells that overexpress β2-adrenoceptor or β2-adrenoceptor–Gs fusion. Accordingly, treatment of cells with methyl-β-cyclodextrin, a caveola-disrupting agent, did not affect β2-adrenoceptor-induced cAMP response. Likewise, these responses were insensitive to caveolin 1 and 2 overexpression. On the other hand, methyl-β-cyclodextrin treatment did decrease β2-adrenoceptor-induced ERK phosphorylation. However, the latter effect of methyl-β-cyclodextrin could be attributed to a non-specific effect rather than its ability to disrupt membrane microdomains. We showed that localization in the raft microdomains did not affect the signalling efficiency of β2-adrenoceptor–Gs–adenylate cyclase pathway, and that methyl-β-cyclodextrin may inhibit signalling by directly affecting the signalling system independently of its caveola-disrupting property. [Copyright &y& Elsevier]

Abstract: The present study was designed to investigate the contribution of endothelial cell caveolae to vascular relaxation in aortas from a normotensive (2K) and renal hypertensive (2K-1C) rat. For that purpose, concentration–effect curves to acetylcholine were constructed in 2K and 2K-1C intact endothelium aortic rings, in the absence or in the presence of the caveolae disassembler methyl-β-ciclodextrin. The potency (pD2) and the maximum relaxant effect to acetylcholine were greater in 2K than in 2K-1C aortas. Methyl-β-ciclodextrin reduced the pD2 in 2K and the maximum relaxant effect in both 2K and 2K-1C. The quantification of the caveolae number by electronic microscopy has shown a larger number of caveolae in 2K than in 2K-1C endothelial cells, which was reduced by methyl-β-ciclodextrin in both 2K and 2K-1C. The production of NO stimulated with acetylcholine was greater in 2K than in 2K-1C endothelial cells, and this effect was impaired by methyl-β-ciclodextrin in both 2K and 2K-1C. The cytosolic Ca2+ concentration ([Ca2+]c) was simultaneously measured in endothelial and smooth muscle cells stimulated with acetylcholine by confocal image of aortic slices. Acetylcholine produced a greater [Ca2+]c increase in 2K than in 2K-1C endothelial cells, which response was inhibited by methyl-β-ciclodextrin only in 2K cells. In smooth muscle cells the reduction of [Ca2+]c was higher in 2K than in 2K-1C. This effect was inhibited by methyl-β-ciclodextrin only in 2K cells. Taken together, our results suggest that the decreased number of caveolae in the endothelial cells from 2K-1C rat aortas is involved in the impaired effect of acetylcholine on [Ca2+]c and NO. [Copyright &y& Elsevier]

To cite this article: Mattila P, Renkonen J, Toppila-Salmi S, Parviainen V, Joenväärä S, Alff-Tuomala S, Nicorici D, Renkonen R. Time-series nasal epithelial transcriptomics during natural pollen exposure in healthy subjects and allergic patients. Allergy 2010; 65: 175–183. Background: The role of epithelium has recently awakened interest in the studies of type I hypersensitivity. Objective: We analysed the nasal transcriptomics epithelial response to natural birch pollen exposure in a time series manner. Methods: Human nasal epithelial cell swabs were collected from birch pollen allergic patients and healthy controls in winter season. In addition, four specimens at weekly intervals were collected from the same subjects during natural birch pollen exposure in spring and transcriptomic analyses were performed. Results: The nasal epithelium of healthy subjects responded vigorously to allergen exposure. The immune response was a dominating category of this response. Notably, the healthy subjects did not display any clinical symptoms regardless of this response detected by transcriptomic analysis. Concomitantly, the epithelium of allergic subjects responded also, but with a different set of responders. In allergic patients the regulation of dyneins, the molecular motors of intracellular transport dominated. This further supports our previous hypothesis that the birch pollen exposure results in an active uptake of allergen into the epithelium only in allergic subjects but not in healthy controls. Conclusion: We showed that birch pollen allergen causes a defence response in healthy subjects, but not in allergic subjects. Instead, allergic patients actively transport pollen allergen through the epithelium to tissue mast cells. Our study showed that new hypotheses can arise from the application of discovery driven methodologies. To understand complex multifactorial diseases, such as type I hypersensitivity, this kind of hypotheses might be worth further analyses. [ABSTRACT FROM AUTHOR]

Background: Previous work in type-I pollen allergies has mainly focused on lymphocytes and immune responses. Here, we begin to analyse with a systems biology view the differences in conjunctival epithelium obtained from healthy and allergic subjects. Methods: Transcriptomics analysis combined with light and electron microscopic analysis of birch pollen allergen Bet v 1 located within conjunctival epithelial cells and tissues from birch allergic subjects and healthy controls was carried out. Results: Bet v 1 pollen allergen bound to conjunctival epithelial cells within minutes after the exposure even during the nonsymptomatic winter season only in allergic, but not in healthy individuals. Light- and electron microscopy showed that Bet v 1 was transported through the epithelium within lipid rafts/caveolae and reached mast cells only in allergic patients, but not in healthy individuals. Transcriptomics yielded 22 putative receptors expressed at higher levels in allergic epithelium compared with healthy specimens. A literature search indicated that out of these receptors, eight (i.e. 37%) were associated with lipid rafts/caveolae, which suggested again that Bet v 1 transport is lipid raft/caveola-dependent. Conclusions: We show a clear difference in the binding and uptake of Bet v 1 allergen by conjunctival epithelial cells in allergic vs healthy subjects and several putative lipid raft/caveolar receptors were identified, which could mediate or be co-transported with this entry. The application of discovery driven methodologies on human conjunctival epithelial cells and tissues can provide new hypotheses worth a further analysis to the molecular mechanisms of a complex multifactorial disease such as type-I birch pollen allergy. [ABSTRACT FROM AUTHOR]

We introduce a novel high resolution scanning surface confocal microscopy technique that enables imaging of endocytic pits in apical membranes of live cells for the first time. The improved topographical resolution of the microscope together with simultaneous fluorescence confocal detection produces pairs of images of cell surfaces sufficient to identify single endocytic pits. Whilst the precise position and size of the pit is detected by the ion conductance microscope, the molecular nature of the pit, e.g. clathrin coated or caveolae, is determined by the corresponding green fluorescent protein fluorescence. Also, for the first time, we showed that flotillin 1 and 2 can be found co-localising with ~200-nm indentations in the cell membrane that supports involvement of this protein in endocytosis. [ABSTRACT FROM AUTHOR]

The idea that G protein-coupled receptors (GPCRs) may undergo homo- or hetero-oligomerization, although highly controversial up to a few years ago, has recently gained wide acceptance. The recognition that GPCRs may exhibit either dimeric or oligomeric structures is based upon a large body of biochemical and biophysical evidence. While much effort has been spent to demonstrate the mechanism(s) by which GPCRs interact with each other, the physiological relevance of this phenomenon remains rather elusive. GPCR oligomerization has been proposed to play a role in receptor ontogeny by either chaperoning protein folding or controlling trafficking to the cell surface. However, the acquisition of these roles does not rule out the possibility that oligomeric receptors may have additional functions, once they are brought to the cell surface. Herein, we propose that protein–protein as well as protein–lipid interactions may provide the structural basis for organizing distinct cell compartments along the plasma membrane where different extracellular signals may be perceived and discriminated. [ABSTRACT FROM AUTHOR]

Treatment of cells with pervanadate or vanadate induces the phosphorylation of caveolin-1 and its internalization from the cell surface, but the intracellular fate of caveolae has not been fully elucidated. In the present study, we examined the fate of endocytosed caveolae in human umbilical vein endothelial cells and mouse endothelial KOP2.16 cells. The localization of internalized caveolae and their relationship with the endosomes were examined by immunofluorescence microscopy as well as by immunoprecipitation and chasing of biotinylated transferrin. In untreated cells, caveolin-1 was mostly confined to the cell surface. When cells were treated with either pervanadate for 30 min or vanadate for 3 h, many caveolin-1-labeled vesicles were formed inside the cells, some of which were colocalized with Rab5 or Rab4. The internalized caveolin-1 was colocalized with the endocytosed transferrin in the Rab5-, Rab4- or early endosome antigen-1-labeled compartment where caveolin-1 was phosphorylated. It then moved to the Rab11-associated compartment. Immunogold electron microscopy revealed that internalized caveolin-1 colocalized with Rab5 or Rab4 in vesicles larger than caveolae. These results suggest that the internalized caveolae interact with early endosomes. [ABSTRACT FROM AUTHOR]

This study tested whether sarcoplasmic-endoplasmic reticulum Ca2+-ATPase regulates the ability of endothelin receptor antagonist to inhibit the endothelin- 1 constriction. The endothelin A receptor antagonist BQ-123 (1 µM) completely relaxed constriction to 10 nM endothelin- 1 in endothelium-denuded rat aorta. Challenge with cyclopiazonic acid (10 µM), a sarcoplasmic-endoplasmic reticulum Ca2+-ATPase inhibitor, during the plateau of endothelin-1 constriction enhanced the constriction by ~30%. BQ-123 relaxed the endothelin-1 plus cyclopiazonic acid constriction by only ~10%. In contrast, prazosin (1 µM), an α-adrenergic receptor antagonist, still completely relaxed the 0.3 µM phenylephrine constriction in the presence of cyclopiazonic acid. Verapamil relaxed the endothelin-1 plus cyclopiazonic acid constriction by ~30%, whereas Ni2+ and 2-aminoethoxydiphenyl borate, nonselective cation channel and store-operated channel blockers, respectively, completely relaxed the constriction. These results suggest that lowered sarcoplasmic-endoplasmic reticulum Ca2+-ATPase activity selectively decreases the ability of endothelin receptor antagonist to inhibit the endothelin A receptor. The decreased antagonism may be related to the opening of store-operated channels and subsequent greater internalization of endothelin A receptor. [ABSTRACT FROM AUTHOR]

Abstract: Neurofibromin (Nf1) is a ∼280kDa protein having tumor suppressor function, presumably by virtue of its GTPase activating domain, but little is known regarding molecular aspects of its effector pathways. Caveolin-1 (Cav-1) regulates diverse signaling molecules and has itself been implicated as a tumor suppressor. Here we demonstrate that Nf1 binds to Cav-1’s scaffolding domain and co-immunoprecipitates with Cav-1. Analysis of Nf1’s primary structure reveals four potential caveolin binding domains, and interestingly, in individuals with neurofibromatosis I, missense mutations occur with high frequency in 3 of the 4 putative domains. We show that Nf1 modulates ras, Akt, and focal adhesion kinase pathways, thereby affecting cytoskeletal organization; moreover, Nf1’s effects on signaling are altered when lipid rafts and caveolae are disrupted by cholesterol depletion. These novel findings provide insight into possible signaling mechanisms of Nf1 and suggest that together Nf1 and Cav-1 may coordinately regulate cell growth and differentiation. [Copyright &y& Elsevier]

Abstract: Growth factor receptors have been shown to be localized to lipid rafts and caveolae. Consistent with a role for these cholesterol-enriched membrane domains in growth factor receptor function, the binding and kinase activities of growth factor receptors are susceptible to regulation by changes in cholesterol content. Furthermore, knockouts of caveolin-1, the structural protein of caveolae, have confirmed that this protein, and by implication caveolae, modulate the ability of growth factor receptors to signal. This article reviews the findings pertinent to the relationship between growth factor receptors, lipid rafts and caveolae and presents a model for understanding the disparate observations regarding the role of membrane microdomains in the regulation of growth factor receptor function. [Copyright &y& Elsevier]

Caveolae are free cholesterol-rich invaginated microdomains of the cell surface characterized by the presence of one or more structural proteins (caveolins). The cholesterol-binding capacity of caveolin plays a key role in the organization of signaling complexes within caveolae. Caveolae are particularly rich in multiprotein signaling complexes containing protein growth factor receptors or integrins. Immunoprecipitation of caveolins from cells labeled with 3H free cholesterol (FC) allows proteins and lipids present in caveolae to be identified at intervals following the initiation of signal transduction. Signaling was found to be associated with transient loss of caveolin-associated FC, stimulation of FC efflux, and phosphorylation of caveolin at a sensitive tyrosine residue. FC within caveolae is labile and responsive to changes in the local composition of signaling complexes. In view of the extended residence of caveolae at the cell surface, these data imply that caveolae take part in an FC cycle initiated by the binding of ligand to its transmembrane kinase. Regulated loss of FC from caveolae is followed by a recovery phase when FC content is restored. These changes form an essential part of signal transduction from the cell surface for caveolae-associated signaling complexes. [Copyright &y& Elsevier]

Caveolins have been identified as key components of caveolae, specialized cholesterol-enriched raft domains visible as small flask-shaped invaginations of the plasma membrane. In polarized MDCK cells caveolin-1 and -2 are found together on basolateral caveolae whereas the apical membrane, where only caveolin-1 is present, lacks caveolae. Expression of a caveolin mutant prevented the formation of the large caveolin-1/-2 hetero-oligomeric complexes, and led to intracellular retention of caveolin-2 and disappearance of caveolae from the basolateral membrane. Correspondingly, in MDCK cells over-expressing caveolin-2 the basolateral membrane exhibited an increased number of caveolae. These results indicate the involvement of caveolin-2 in caveolar biogenesis. [Copyright &y& Elsevier]

Restoration of cell volume after cell swelling in mammalian cells is achieved by the loss of solutes (K+, Cl−, and organic osmolytes) and the subsequent osmotically driven efflux of water. This process is generally known as regulatory volume decrease (RVD). One pathway for the swelling induced loss of Cl− (and also organic osmolytes) during RVD is the volume-regulated anion channel (VRAC). In this review, we discuss the physiological role and cellular control of VRAC. We will first highlight evidence that VRAC is more than a volume regulator and that it participates in other fundamental cellular processes such as cell proliferation and apoptosis. The second part concentrates on the Rho/Rho kinase/myosin phosphorylation cascade and on compartmentalization in caveolae as modulators of the signal transduction cascade that controls VRAC gating in vascular endothelial cells. [ABSTRACT FROM AUTHOR]

The discovery of small, "cave-like" invaginations at the plasma membrane, called caveola, has opened up a new and exciting research area in health and diseases revolving around this cellular ultrastructure. Caveolae are rich in cholesterol and orchestrate cellular signaling events. Within caveola, the caveola-associated proteins, caveolins and cavins, are critical components for the formation of these lipid rafts, their dynamics, and cellular pathophysiology. Their alterations underlie human diseases such as lipodystrophy, muscular dystrophy, cardiovascular disease, and diabetes. The expression of caveolins and cavins is modulated in tumors and in tumor stroma, and their alterations are connected with cancer progression and treatment resistance. To date, although substantial breakthroughs in cancer drug development have been made, drug resistance remains a problem leading to treatment failures and challenging translation and bench-to-bedside research. Here, we summarize the current progress in understanding cancer drug resistance in the context of caveola-associated molecules and tumor stroma and discuss how we can potentially design therapeutic avenues to target these molecules in order to overcome treatment resistance.

An increase in intracellular Ca 2+ concentration ([Ca 2+ ] i ) activates Ca 2+ -sensitive enzymes such as Ca 2+ /calmodulin-dependent kinases (CaMK) and induces gene transcription in various types of cells. This signaling pathway is called excitation-transcription (E-T) coupling. Recently, we have revealed that a L-type Ca 2+ channel/CaMK kinase (CaMKK) 2/CaMK1α complex located within caveolae in vascular smooth muscle cells (SMCs) can convert [Ca 2+ ] i changes to gene transcription profiles that are related to chemotaxis. Although CaMK1α is expected to be the key molecular identity that can transport Ca 2+ signals originated within caveolae to the nucleus, data sets directly proving this scheme are lacking. In this study, multicolor fluorescence imaging methods were utilized to address this question. Live cell imaging using mouse primary aortic SMCs revealed that CaMK1α can translocate from the cytosol to the nucleus; and that this movement was blocked by nifedipine or a CaMKK inhibitor, STO609. Experiments using two types of Ca 2+ chelators, ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) and 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), combined with caveolin-1 knockout (cav1-KO) mice showed that local Ca 2+ events within caveolae are required to trigger this CaMK1α nuclear translocation. Importantly, overexpression of cav1 in isolated cav1-KO myocytes recovered the CaMK1α translocation. In SMCs freshly isolated from mesenteric arteries, CaMK1α was localized mainly within caveolae in the resting state. Membrane depolarization induced both nuclear translocation and phosphorylation of CaMK1α. These responses were inhibited by nifedipine, STO609, cav1-KO, or BAPTA. These new findings strongly suggest that CaMK1α can transduce Ca 2+ signaling generated within or very near caveolae to the nucleus and thus, promote E-T coupling.

Caveolae are bulb-shaped invaginations of the plasma membrane that are enriched in specific lipids including cholesterol, phosphatidylserine and sphingolipids. Caveolae have many described cellular roles and functions, including endocytic transport, transcytosis, mechanosensing, and serving as a buffer against plasmalemmal stress. Caveola are formed through interactions between integral membrane proteins (Caveolin) and a cavin family of peripheral proteins (Cavins). Nearly half of the human proteome resides within or at the surface of membranes. Studying protein-protein interactions, especially of transmembrane domain containing proteins can be challenging. Fortunately, sophisticated biophysical methods allow for the monitoring of protein interactions in intact cells. Here, we describe the principles of Förster resonance energy transfer, fluorescence lifetime, and how their properties can be used to assess protein-protein interactions. Additionally, we discuss and demonstrate how fluorescence lifetime can be monitored microscopically thereby providing caveolin-cavin interaction data from living cells., (© 2022. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Paraquat dichloride (PQ) is an effective and widely used herbicide for eliminating weeds. However, once being accidentally or voluntarily ingested, PQ-poisoned patients have the very high incidence of adult respiratory distress syndrome because lung can actively absorb PQ. Since the 1970s, evidence suggested that polyamine competitively inhibited uptake of PQ into lung tissue; therefore, polyamine transport system has been regarded as an important vehicle for PQ uptake into lung. However, so far, we cannot clone or detect the polyamine transport system in mammalian animal. Recent evidence from diverse sources has suggested that caveola may be an important vehicle for polyamine absorption into lung. Herein we hypothesise that caveola is a key vehicle for PQ uptake in lung and hence blocking the expression of caveola may serve as new targets for treatment of PQ poisoning. [ABSTRACT FROM AUTHOR]

In biology, the modern scientific fashion is to mostly study proteins. Much less attention is paid to lipids. However, lipids themselves are extremely important for the formation and functioning of cellular membrane organelles. Here, the role of the geometry of the lipid bilayer in regulation of organelle shape is analyzed. It is proposed that during rapid shape transition, the number of lipid heads and their size (i.e., due to the change in lipid head charge) inside lipid leaflets modulates the geometrical properties of organelles, in particular their membrane curvature. Insertion of proteins into a lipid bilayer and the shape of protein trans-membrane domains also affect the trans-membrane asymmetry between surface areas of luminal and cytosol leaflets of the membrane. In the cases where lipid molecules with a specific shape are not predominant, the shape of lipids (cylindrical, conical, or wedge-like) is less important for the regulation of membrane curvature, due to the flexibility of their acyl chains and their high ability to diffuse. [ABSTRACT FROM AUTHOR]

Introduction: Rafts are function-structural cell membrane nano-domains. They contribute to explain the efficiency of signal transduction at the low physiological membrane concentrations of the signaling partners by their clustering inside specialized signaling domains., Development: In this article, we review the current model of the membrane rafts and their physio-pathological relevance in the nervous system, including their role in Parkinson, Alzheimer, and Huntington diseases., Conclusions: Rafts disruption/dysfunction has been shown to relate diverse neurological diseases. Therefore, it has been suggested that preservation of membrane rafts may represent a strategy to prevent or delay neuronal dysfunctions in several diseases., (Copyright © 2021 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.)