Caveolin-1 (Cav-1) is a trans-membrane protein that is a major component of the caveolae structure on the plasma membrane. Cav-1 is involved in the regulation of various cellular processes, including cell growth, differentiation, endocytosis, and in particular it has been implied in cellular senescence. Here we review current knowledge about Cav-1 in cellular signaling and discuss the role of Cav-1 in aging-related diseases.
Caveolae ; Caveolin 1 ; Cell Aging ; Cell Membrane ; Endocytosis

This study investigated a nano drug delivery system built by one sort of modified trimethyl chitosan (TMC). The TMC was modified by cRGDyk, ligand of integrin receptor avβ3. Single factor screening was used to optimize the prescription in which the particle sizes of TMC nanoparticle (TMC NPs) and cRGDyk modified TMC nanoparticle (C-TMC NPs) were (240.3 ± 4.2) nm and (259.5 ± 3.3) nm. Electric potential of those two nanoparticles were (33.5 ± 0.8) mV and (25.7 ± 1.6) mV. Encapsulation efficiencies were (76.0 ± 2.2) % and (74.4 ± 2.0) %. Drug loading efficacies were (50.1 ± 2.1) % and (26.1 ± 1.0) %. Then the cellular uptake, uptake mechanism and transport efficacy of TMC NPs and C-TMC NPs were investigated using Caco-2 cell line. The uptake rate and accumulating drug transit dose of C-TMC NPs were 1.98 and 2.84 times higher than TMC NPs, separately. Mechanism investigations revealed that caveolae-mediated endocytosis, clathrin-mediated endocytosis and macropinocytosis were involved in the intercellular uptake of both TMC NPs and C-TMC NPs. What is more, free cRGDyk could remarkably inhibit the uptake of C-TMC NPs.
Biological Transport ; Caco-2 Cells ; Caveolae ; Chitosan ; chemistry ; Clathrin ; Endocytosis ; Humans ; Integrin alphaVbeta3 ; chemistry ; Nanoparticles ; Particle Size ; Pinocytosis

Porphyromonas gingivalis is one of the most important periodontal pathogens and has been to known to invade various types of cells, including endothelial cells. The present study investigated the mechanisms involved in the internalization of P. gingivalis in human umbilical vein endothelial cells (HUVEC). P. gingivalis internalization was reduced by clathrin and lipid raft inhibitors, as well as a siRNA knockdown of caveolin-1, a principal molecule of lipid raft-related caveolae. The internalization was also reduced by perturbation of actin rearrangement, while microtubule polymerization was not required. Furthermore, we found that Src kinases are critical for the internalization of P. gingivalis into HUVEC, while neither Rho family GTPases nor phosphatidylinositol 3-kinase are required. Taken together, this study indicated that P. gingivalis internalization into endothelial cells involves clathrin and lipid rafts and requires actin rearrangement associated with Src kinase activation.
Actins ; Caveolae ; Caveolin 1 ; Clathrin* ; Endothelial Cells* ; GTP Phosphohydrolases ; Human Umbilical Vein Endothelial Cells ; Humans ; Microtubules ; Phosphatidylinositol 3-Kinase ; Phosphotransferases ; Polymerization ; Polymers ; Porphyromonas gingivalis* ; RNA, Small Interfering ; src-Family Kinases

The release of microvesicles(MV) is one of the critical mechanisms underlying the angiogenesis-promoting activity of mesenchymal stem cells(MSC). This study was aimed to explore the appropriate condition under which MSC releases MV. Bone marrow samples from 5 healthy adults were collected, and MSC were isolated, culture-expanded and identified. MSC at passage 5 were suspended in medium without or medium with 10% fetal(FCS) calf serum and seeded into culture dishes. The culture was separately maintained in hypoxia (1% oxygen) or normoxia (around 20% oxygen), and 20 dishes of cells (2×10(6)/dish) were used for each group. The supernatants were collected for MV harvesting. The cell number was counted with trypan blue exclusion test and the protein contents in the MV were determined. MV were identified by observation under an electron microscope. The surface markers on MV were analyzed by flow cytometry. MTT test was performed to observe the pro-proliferative activity of MV that were added into the culture of human umbilical cord vein endothelial cells at a concentration of 10 µg/ml. The results showed that the majority of MV released by MSC were with diameters of less than 100 nm, and MV took the featured membrane-like structure with a hypodense center. They expressed CD29, CD44, CD73 and CD105, while they were negative for CD31 and CD45. The increase multiples of the adherent trypan blue-resistant cells cultured in normoxia with serum, in normoxia without serum, in hypoxia with serum and hypoxia in the absence of serum were 4.05 ± 0.73, 1.77 ± 0.48, 5.80 ± 0.65 and 3.69 ± 0.85 respectively, and the estimated protein contents per 10(8) cells were 463.48 ± 138.74 µg, 1604.07 ± 445.28 µg, 2389.64 ± 476.75 µg and 3141.18 ± 353.01 µg. MTT test showed that MV collected from MSC in hypoxia seemed to promote the growth of endothelial cells more efficiently than those from cells in normoxia. It is concluded that hypoxia can enhance the release of microvesicles from MSC, and cultivation of MSC in hypoxia and medium without serum may provide an appropriate condition for MV harvesting.
Bone Marrow Cells ; cytology ; metabolism ; Caveolae ; metabolism ; Cell-Derived Microparticles ; metabolism ; Cells, Cultured ; Humans ; Mesenchymal Stromal Cells ; cytology ; metabolism

Caveolae are specialized lipid rafts that form flask-shaped invaginations of the plasma membrane. Many researches show that caveolae are involved in cell signaling and transport. Caveolin-1 is the major coat protein essential for the formation of caveolae. Recently, several reports indicated that the other caveolae-associated proteins, Cavins, are required for caveola formation and organization. It's worth noting that Cavin-1 could cooperate with Caveolin-1 to accommodate the structural integrity and function of caveolae. Here, we reviewed that the relationship between Cavins and Caveolins and explore the role of them in regulating caveolae.
Animals ; Caveolae ; physiology ; Caveolin 1 ; metabolism ; physiology ; Caveolins ; metabolism ; physiology ; Humans ; Membrane Proteins ; metabolism ; physiology ; RNA-Binding Proteins ; metabolism ; physiology

Glycosphingolipids (GSLs) are present in all mammalian cell plasma membranes and intracellular membrane structures. They are especially concentrated in plasma membrane lipid domains that are specialized for cell signaling. Plasma membranes have typical structures called rafts and caveola domain structures, with large amounts of sphingolipids, cholesterol, and sphingomyelin. GSLs are usually observed in many organs ubiquitously. However, GSLs, including over 400 derivatives, participate in diverse cellular functions. Several studies indicate that GSLs might have an effect on signal transduction related to insulin receptors and epidermal growth factor receptors. GSLs may modulate immune responses by transmitting signals from the exterior to the interior of the cell. Guillain-Barre syndrome is one of the autoimmune disorders characterized by symmetrical weakness in the muscles of the legs. The targets of the immune response are thought to be gangliosides, which are one group of GSLs. Other GSLs may serve as second messengers in several signaling pathways that are important to cell survival or programmed cell death. In the search for clear evidence that GSLs may play critical roles in various biological functions, many researchers have made genetically engineered mice. Before the era of gene manipulation, spontaneous animal models or chemical-induced disease models were used.
Animals ; Caveolae ; Cell Death ; Cell Membrane ; Cell Survival ; Cholesterol ; Diabetes Mellitus ; Gangliosides ; Glycosphingolipids ; Guillain-Barre Syndrome ; Intracellular Membranes ; Leg ; Mice ; Models, Animal ; Muscles ; Receptor, Epidermal Growth Factor ; Receptor, Insulin ; Second Messenger Systems ; Signal Transduction ; Sphingolipids

Caveolin-2, a protein about 20 kD, is a major component of the inner surface of caveolae, small invaginations of the plasma membrane. Similar with caveolin-1 and caveolin-3, it serves as a protein marker of caveolae. Caveolin-1 and -2 are located next to each other at 7q31.1 on human chromosome, the proteins encoded are co-localized and form a stable hetero-oligomeric complex, distributing similarly in tissue and cultured cells. Caveolin-3 is located on different chromosomes but confirmed to interact with caveolin-2. Caveolin-2 is similar to caveolin-1 in many respects but differs from the latter in functional domains, especially in G-protein binding domain and caveolin scaffolding domain. The mRNAs of both caveolin-1 and caveolin-2 are most abundantly expressed in white adipose tissue and are induced during differentiation of 3T3-L1 cells to adipocytes. Caveolin-2-deficient mice demonstrate clear pulmonary defects, with little or no change in caveolin-1 expression and caveolae formation, suggesting that caveolin-2 plays a selective role in lung functions. Caveolin-2 is also involved in lipid metabolism and human cancers.
Biomarkers ; metabolism ; Caveolae ; metabolism ; Caveolin 2 ; genetics ; metabolism ; Chromosomes, Human, Pair 7 ; Humans

BACKGROUND: Cholesterol is a major component of specialized membrane microdomains known as lipid rafts or caveolae, which modulate the fluidity of biological membranes. Membrane cholesterol therefore plays an important role in cell signaling and vesicular transport. OBJECTIVE: In this study, we investigated the effects of cholesterol on matrix metalloproteinase-1 (MMP-1) expression in human dermal fibroblasts. METHODS: MMP-1 mRNA and protein expression were determined by RT-PCR and Western blotting, respectively. AP-1 DNA binding activity was detected by electrophoretic mobility shift assays. The amount of cholesterol was analyzed by cholesterol assay kit. RESULTS: We observed that MMP-1 mRNA and protein expression was dose-dependently decreased by cholesterol treatment. In contrast, cholesterol depletion by a cholesterol depletion agent, methyl-beta-cyclodextrin (M beta CD) in human dermal fibroblasts, increased MMP-1 mRNA and protein expression in a dose-dependent manner. Also, we investigated the regulatory mechanism of M beta CD-induced MMP-1 expression: cholesterol depletion by M beta CD, activated ERK1/2 and JNK, but not p38 MAPK cascade, and it also significantly increased c-Jun phosphorylation, c-Fos expression and activator protein-1 binding activity. Furthermore, the inhibition of ERK or JNK with specific chemical inhibitors prevented M beta CD-induced MMP-1 expression, which indicates that ERK and JNK play an important role in cholesterol depletion-mediated MMP-1 induction. In addition, M beta CD-induced phosphorylation of ERK and JNK and MMP-1 expression were suppressed by cholesterol repletion. CONCLUSION: Our results suggest that cholesterol regulates MMP-1 expression through the control of ERK and JNK activity in human dermal fibroblasts.
beta-Cyclodextrins ; Blotting, Western ; Caveolae ; Cholesterol ; DNA ; Electrophoretic Mobility Shift Assay ; Fibroblasts ; Humans ; Matrix Metalloproteinase 1 ; Membrane Microdomains ; Membranes ; p38 Mitogen-Activated Protein Kinases ; Phosphorylation ; RNA, Messenger ; Transcription Factor AP-1

We investigated the effect of phenylephrine (PE)- and isoproterenol (ISO)-induced cardiac hypertrophy on subcellular localization and expression of caveolin-3 and STAT3 in H9c2 cardiomyoblast cells. Caveolin-3 localization to plasma membrane was attenuated and localization of caveolin-3 to caveolae in the plasma membrane was 24.3% reduced by the catecholamine-induced hypertrophy. STAT3 and phospho-STAT3 were up-regulated but verapamil and cyclosporin A synergistically decreased the STAT3 and phospho-STAT3 levels in PE- and ISO-induced hypertrophic cells. Both expression and activation of STAT3 were increased in the nucleus by the hypertrophy. Immunofluorescence analysis revealed that the catecholamine-induced hypertrophy promoted nuclear localization of pY705-STAT3. Of interest, phosphorylation of pS727-STAT3 in mitochondria was significantly reduced by catecholamine-induced hypertrophy. In addition, mitochondrial complexes II and III were greatly down-regulated in the hypertrophic cells. Our data suggest that the alterations in nuclear and mitochondrial activation of STAT3 and caveolae localization of caveolin-3 are related to the development of the catecholamine-induced cardiac hypertrophy.
Animals ; Catecholamines/*pharmacology ; Caveolae/*metabolism ; Caveolin 3/*metabolism ; Cell Line ; Hypertrophy/metabolism ; Mitochondria/*metabolism ; Myocardium/cytology/*pathology ; Myocytes, Cardiac/cytology/*drug effects/metabolism ; Rats ; STAT3 Transcription Factor/*metabolism

PURPOSE: A family of organic anion transporters (OAT) has been identified, and several isoforms have been reported. The regulatory mechanisms of OATs functions, however, still remain to be elucidated. The rat OAT1 contributes to move a number of negatively-charged organic compounds between cells and their extracellular milieu. Caveolin (Cav) also plays a role in membrane transport. To address this issue, we investigated the protein-protein interaction between rOAT1 and Cav-1. METHODS: The expressions of rOAT1 and Cav-1 (mRNA and protein) were evaluated using RT-PCR and Western blot analysis. The localization of rOAT1 and Cav-1 was determined in the caveolae-rich membrane fraction isolated by sucrose density gradient ultra-centrifugation. For the direct binding between the rOAT1 and Cav-1 proteins, the immuno-precipitation method and confocal microscopy were employed. To perform functional analysis, a Xenopus oocytes expression system with the antisense oligonucleotides (ODN) technique was used. RESULTS: The expressions of rOAT1 and Cav-1 were detected in the kidney. The caveolae-rich membranous fractions from the kidney contained both rOAT1 and Cav-1 in the same fractions. The immuno-precipitation experiments showed the formation of a complex between the rOAT1 and Cav-1. The confocal microscopy using primary cultured renal proximal epithelial cells also supported the co-localization of rOAT1 and Cav-1 at the plasma membrane. The uptake function of rOAT1, as assessed by using a Xenopus oocytes expression system, was inhibited by the Xenopus Cav-1 antisense ODN. CONCLUSION: rOAT1 co-localizes with caveolin-1 in the caveolae, and caveolin-1 plays an important role in regulating the function of rOAT1.
Animals ; Avena ; Blotting, Western ; Caveolae ; Caveolin 1 ; Cell Membrane ; Epithelial Cells ; Humans ; Ketoglutaric Acids ; Kidney ; Kidney Tubules, Proximal ; Membranes ; Microscopy, Confocal ; Oligonucleotides, Antisense ; Oocytes ; Organic Anion Transporters ; Protein Isoforms ; Proteins ; Rats ; Sucrose ; Xenopus