Expression Of Cavin-1 Research Articles

Expression of the Cavin Family in Childhood Leukemia and Its Implications in Subtype Diagnosis and Prognosis Evaluation.

BackgroundCaveolae are plasma membrane subdomains of many mammalian cells that play critical roles in cellular processes, including endocytosis, signal transduction and tumorigenesis. Cavin proteins are essential for caveola formation, structure and function and are reported to be involved in various human diseases, but little is known about their expression and prognostic value in leukemia.MethodsWe performed a detailed analysis of Cavin family mRNA expression levels in different cancer tissues vs. normal tissues via the ONCOMINE, Gene Expression Profiling Interactive Analysis (GEPIA) and Cancer Cell Line Encyclopedia (CCLE) databases. Then, we used qRT-PCR and Western blotting to validate Cavin1-4 expression in 10 fresh leukemia samples. Moreover, we estimated their prognostic value in leukemia with the R programming language and GEPIA database.ResultsThe expression of Cavin members is low in most human cancers, especially in leukemia. Cavin-1 and Cavin-2 are often more expressed in myeloid leukemia than lymphoblastic leukemia, but Cavin-4 has the opposite pattern. Interestingly, low expression of CAVIN1 and CAVIN4 is correlated with poorer outcome but low CAVIN2 expression is associated with a significantly better leukemia prognosis in leukemia.ConclusionThe Cavin family showed significant expression differences between leukemia and normal cells. High Cavin-2 and low Cavin-4 levels predict poor survival and could be promising subtype diagnosis and prognosis biomarkers for leukemia.

Cavin-1 promotes M2 macrophages/microglia polarization via SOCS3

Our study aimed to investigate the function of Cavin-1 and SOCS3 in macrophages/microglia M2 polarization and further explored the relevant mechanism. Expression levels of Cavin-1 and SOCS3 in macrophages/microglia were measured by western blotting and RT-PCR, respectively. Then, Cavin-1 or SOCS3 was gene silenced by a siRNA approach, and gene silencing efficiency was determined by western blotting. Next, co-immunoprecipitation (Co-IP) was employed to further analyze the interaction between Cavin-1 and SOCS3. Finally, the activation of STAT6/PPAR-γ signaling was evaluated using western blotting, and the M2 macrophages/microglia polarization was validated by measuring the mRNA expression of M2 markers by RT-PCR. In the polarization process of macrophages/microglia to M2 phenotype, both Cavin-1 and SOCS3 increased synchronously at protein and mRNA level, reached the peak at the 6h, and then decreased. After Cavin-1 or SOCS3 silencing, the expression of Cavin-1 and SOCS3 declined. These results suggested that Cavin-1 and SOCS3 were positively correlated in macrophages/microglia, and this conjecture was verified by Co-IP. Besides, Cavin-1 silencing not only suppressed the activation of STAT6/PPAR-γ pathway, but also suppressed the release of anti-inflammatory factors. Finally, we found that SOCS3 overexpression reversed the inhibitory effect of Cavin-1 silencing on the release of anti-inflammatory factors in M2 macrophages/microglia. Cavin-1 and SOCS3 are actively involved in the process of M2 macrophages/microglia polarization. As a SOCS3 interacting protein, Cavin-1 can promote M2 macrophages/microglia polarization via SOCS3.

Abstract 10197: Cavin1, a Novel Actor in Drug Induced Long Qt

Introduction: Many drugs have been pulled from the market due to their undesirable effect in prolonging the QT interval by altering cardiac ion currents, notably I Kr generated by hERG. This cardiotoxic impact is however extremely variable between individuals and the mechanisms underlying this variability remain undiscovered. Previously, we identified a higher expression of CAVIN1, an essential protein for caveolae biogenesis, in cardiomyocytes (CM) derived from individuals with high susceptibility to develop sotalol-induced long QT. Hypothesis: CAVIN1 can modulate cardiomyocytes’ response to drugs. Methods: We used induced pluripotent stem cells-derived-CM (iCM) from 3 subjects with the highest sensitivity (HS) to sotalol (ie, those with the highest increase in QTc) and 3 others with the lowest sensitivity to sotalol (LS). Results: cardiac repolarization and I Kr were similar between HS-iCM and LS-iCM at baseline. However, HS-iCM displayed a significantly higher prolongation of the repolarization phase along with a decrease in I Kr in response to sotalol and other drugs targeting hERG (E4031, vandetanib, and clarithromycin). CAVIN1 mRNA and protein levels were increased by 2-fold in the HS-iCM. Overexpressing CAVIN1 in the LS-iCM using adenovirus induced higher sensitivity to sotalol and the other hERG blockers. In contrast, CAVIN1 knockdown using siRNA in the HS-iCM switched their phenotype to a lower sensitivity to hERG blockers. We observed that CAVIN1 overexpression in LS-iCM and HEK cells changed hERG distribution within cells with accumulation at the membrane. We applied Methyl-β-cyclodextrin, a detergent that removes caveolae from membranes, and found that caveolae depletion induced prolonged repolarization associated with a decrease in CAVIN1 and hERG sarcolemmal expression, and their accumulation in the cytoskeleton. In contrast with the LS-iCM, sotalol application in the HS-iCM promoted hERG internalization into the cytoskeleton. Conclusions: We identified CAVIN1 as a novel modulator of cardiac repolarization in response to drug by promoting hERG internalization. This represents a novel mechanism sustaining the inter-individual variability in response to drugs.

Caveolák szerepe a szürke hályog képződésében: humán szemlencse epithelsejtjeinek vizsgálata

The aim of the study was to examine and compare the morphology of caveolae and the immunohistochemical difference of caveolin-1 in control (myopic and hyperopic) lens epithelial cells and human lens epithelial cells affected by cataract. Authors investigated whether caveolae might have a role in cataractogenesis. Anterior lens capsules were obtained by capsulorhexis during surgery of senile cataract and refractive surgery of the clear lens. Ultra-fine sections have been studied by transmission electron microscopy, and semi-fine samples were labelled for immunohistochemistry with polyclonal caveolin-1 and cavin-1 antibodies. By immunohistochemistry, in the control group, significant caveolin-1 label with low cavin-1 signal were measured in the lens epithelial cells. In the cataract group high cavin-1 and caveolin-1 expression was detected. In the control group, caveolae were not observed, but in the lens epithelial cells with cataract, increased number of caveolae have been detected by electron microscopy. For the development and maintenance of the specific caveolae shape, caveolin-1 is needed to be accompanied by cavin-1. Therefore, it is presumable that the increased expression of cavin-1 could explain the higher number of caveolae in the cataract group. These results might suggest that caveolae might play a role in cataractogenesis. Orv Hetil. 2019; 160(8): 300-308.

Vimentin intermediate filaments function as a physical barrier during intracellular trafficking of caveolin-1

Both the cytoskeletal intermediate filaments (IFs) and cytoplasmic caveolae contribute to active processes such as cell migration, morphogenesis and vesicular trafficking, but the interplay between these two systems has remained elusive. Here, we find that vimentin and nestin IFs interact with caveolae central component caveolin-1 (CAV-1) and importantly, restrain the intracellular trafficking of CAV-1 positive vesicles by serving as a physical barrier. Consequently, CAV-1 vesicles show less density and mobility in vimentin IFs enriched region, which is a substrate stiffness independent process. Moreover, depletion of vimentin IFs releases the slow movement proportion of CAV-1 positive vesicles and thus increases their cytoplasmic dynamics, whereas the expression of caveolae-associated protein CAV-1, CAV-2 and cavin-1 were unaffected. Collectively, these results reveal a negative role of IFs in regulating the trafficking of intracellular CAV-1 vesicles in live cells.

Fam198a, a member of secreted kinase, secrets through caveolae biogenesis pathway.

Fam198a is a member of four-jointed protein kinases, a secreted protein kinase family. It was identified as a caveolae-associated protein and colocalized with cavin-1 and caveolin-1 in both tissues and cells. The newly synthesized Fam198a precursor in endoplasmic reticulum (ER) was transported by caveolae biogenesis vesicles to Golgi apparatus in which it was proteolytically cleaved into the secreted mature form. The amino acid mutation analysis identified Arg 120 and 437 as the proteolytic sites in Fam198a precursor during maturation. In mouse embryo fibroblasts (MEFs) obtained from cavin-1-/- or caveolin-1-/- mice, Fam198a precursor was retained in ER and no mature Fam198a could be formed in these cells. Ectopic expression of exogenous cavin-1 in cavin-1-/- MEFs restored the blocked Fam198a post-translational process and secretion. Cavin-1 was also required for Fam198a secretion after its maturation in Golgi apparatus. Ectopic expression of cavin-1 in A549 cells restored the blocked Fam198a secretion. These results suggest that protein secretion is an important function for caveolae biogenesis pathway and the disruption of caveolae system will affect those functions played by the secreted proteins.

Interaction of suppressor of cytokine signalling 3 with cavin-1 links SOCS3 function and cavin-1 stability

Effective suppression of JAK–STAT signalling by the inducible inhibitor “suppressor of cytokine signalling 3” (SOCS3) is essential for limiting signalling from cytokine receptors. Here we show that cavin-1, a component of caveolae, is a functionally significant SOCS3-interacting protein. Biochemical and confocal imaging demonstrate that SOCS3 localisation to the plasma membrane requires cavin-1. SOCS3 is also critical for cavin-1 stabilisation, such that deletion of SOCS3 reduces the expression of cavin-1 and caveolin-1 proteins, thereby reducing caveola abundance in endothelial cells. Moreover, the interaction of cavin-1 and SOCS3 is essential for SOCS3 function, as loss of cavin-1 enhances cytokine-stimulated STAT3 phosphorylation and abolishes SOCS3-dependent inhibition of IL-6 signalling by cyclic AMP. Together, these findings reveal a new functionally important mechanism linking SOCS3-mediated inhibition of cytokine signalling to localisation at the plasma membrane via interaction with and stabilisation of cavin-1.

Hypoxia Inhibits Cavin-1 and Cavin-2 Expression and Down-Regulates Caveolae in Adipocytes

During obesity, a hypoxic state develops within the adipose tissue, resulting in insulin resistance. To understand the underlying mechanism, we analyzed the involvement of caveolae because they play a crucial role in the activation of insulin receptors. In the present study, we demonstrate that in 3T3-L1 adipocytes, hypoxia induces the disappearance of caveolae and inhibits the expression of Cavin-1 and Cavin-2, two proteins necessary for the formation of caveolae. In mice, hypoxia induced by the ligature of the spermatic artery results in the decrease of cavin-1 and cavin-2 expression in the epididymal adipose tissue. Down-regulation of the expression of cavins in response to hypoxia is dependent on hypoxia-inducible factor-1. Indeed, the inhibition of hypoxia-inducible factor-1 restores the expression of cavins and caveolae formation. Expression of cavins regulates insulin signaling because the silencing of cavin-1 and cavin-2 impairs insulin signaling pathway. In human, cavin-1 and cavin-2 are decreased in the sc adipose tissue of obese diabetic patients compared with lean subjects. Moreover, the expression of cavin-2 correlates negatively with the homeostatic model assessment index of insulin resistance and glycated hemoglobin level. In conclusion, we propose a new mechanism in which hypoxia inhibits cavin-1 and cavin-2 expression, resulting in the disappearance of caveolae. This leads to the inhibition of insulin signaling and the establishment of insulin resistance.

Caveolin-1 expression and cavin stability regulate caveolae dynamics in adipocyte lipid store fluctuation.

Adipocytes specialized in the storage of energy as fat are among the most caveolae-enriched cell types. Loss of caveolae produces lipodystrophic diabetes in humans, which cannot be reversed by endothelial rescue of caveolin expression in mice, indicating major importance of adipocyte caveolae. However, how caveolae participate in fat cell functions is poorly understood. We investigated dynamic conditions of lipid store fluctuations and demonstrate reciprocal regulation of caveolae density and fat cell lipid droplet storage. We identified caveolin-1 expression as a crucial step in adipose cell lines and in mice to raise the density of caveolae, to increase adipocyte ability to accommodate larger lipid droplets, and to promote cell expansion by increased glucose utilization. In human subjects enrolled in a trial of 8 weeks of overfeeding to promote fattening, adipocyte expansion response correlated with initial caveolin-1 expression. Conversely, lipid mobilization in cultured adipocytes to induce lipid droplet shrinkage led to biphasic response of cavin-1 with ultimate loss of expression of cavin-1 and -3 and EHD2 by protein degradation, coincident with caveolae disassembly. We have identified the key steps in cavin/caveolin interplay regulating adipocyte caveolae dynamics. Our data establish that caveolae participate in a unique cell response connected to lipid store fluctuation, suggesting lipid-induced mechanotension in adipocytes.

Endocytic Crosstalk: Cavins, Caveolins, and Caveolae Regulate Clathrin-Independent Endocytosis

Author SummaryEndocytosis is the process that allows cells to take up molecules from the environment. Several endocytic pathways exist in mammalian cells. While the best understood endocytic pathway uses clathrin, recent years have seen a great increase in our understanding of clathrin-independent endocytic pathways. Here we characterize the crosstalk between caveolae, flask-shaped specialized microdomains present at the plasma membrane, and a second clathrin-independent pathway, the CLIC/GEEC Cdc42-regulated endocytic pathway. These pathways are segregated in migrating cells with caveolae at the rear and CLIC/GEEC endocytosis at the leading edge. Here we find that specific caveolar proteins, caveolins and cavins, can also negatively regulate the CLIC/GEEC pathway. With the help of several techniques, including quantitative electron microscopy analysis and real-time live-cell imaging, we demonstrate that expression of caveolar proteins affects early carrier formation, causes cellular lipid changes, and changes the activity of the key regulator of the CLIC/GEEC pathway, Cdc42. The functional consequences of loss of caveolar proteins on the CLIC/GEEC pathway included inhibition of polarized cell migration and increased endocytosis in tissue explants.

Arterial dysfunction but maintained systemic blood pressure in cavin-1-deficient mice.

Caveolae are omega-shaped plasma membrane micro-domains that are abundant in cells of the vascular system. Formation of caveolae depends on caveolin-1 and cavin-1 and lack of either protein leads to loss of caveolae. Mice with caveolin-1 deficiency have dysfunctional blood vessels, but whether absence of cavin-1 similarly leads to vascular dysfunction is not known. Here we addressed this hypothesis using small mesenteric arteries from cavin-1-deficient mice. Cavin-1-reporter staining was intense in mesenteric arteries, brain arterioles and elsewhere in the vascular system, with positive staining of both endothelial and smooth muscle cells. Arterial expression of cavin-1, -2 and -3 was reduced in knockout (KO) arteries as was expression of caveolin-1, -2 and -3. Caveolae were absent in the endothelial and smooth muscle layers of small mesenteric arteries as determined by electron microscopy. Arginase, a negative regulator of nitric oxide production, was elevated in cavin-1 deficient arteries as was contraction in response to the α1-adrenergic agonist cirazoline. Detailed assessment of vascular dimensions revealed increased media thickness and reduced distensibility, arguing that enhanced contraction was due to increased muscle mass. Contrasting with increased α1-adrenergic contraction, myogenic tone was essentially absent and this appeared to be due in part to increased nitric oxide production. Vasomotion was less frequent in the knock-out vessels. In keeping with the opposing influences on arterial resistance of increased agonist-induced contractility and reduced myogenic tone, arterial blood pressure was unchanged in vivo. We conclude that deficiency of cavin-1 affects the function of small arteries, but that opposing influences on arterial resistance balance each other such that systemic blood pressure in unstressed mice is well maintained.

S138 Blood outgrowth endothelial cells isolated from patients with pulmonary arterial hypertension possess less caveolae and reduced cavin-2 expression

Pulmonary arterial hypertension (PAH) is a progressive disease characterised by a marked elevation in pulmonary arterial pressure due to increased muscularisation and obliteration of small pulmonary arteries. The majority of...

PTRF/cavin-1 neutralizes non-caveolar caveolin-1 microdomains in prostate cancer.

Caveolin-1 has a complex role in prostate cancer and has been suggested to be a potential biomarker and therapeutic target. As mature caveolin-1 resides in caveolae, invaginated lipid raft domains at the plasma membrane, caveolae have been suggested as a tumor-promoting signaling platform in prostate cancer. However, caveola formation requires both caveolin-1 and cavin-1 (also known as PTRF; polymerase I and transcript release factor). Here, we examined the expression of cavin-1 in prostate epithelia and stroma using tissue microarray including normal, non-malignant and malignant prostate tissues. We found that caveolin-1 was induced without the presence of cavin-1 in advanced prostate carcinoma, an expression pattern mirrored in the PC-3 cell line. In contrast, normal prostate epithelia expressed neither caveolin-1 nor cavin-1, while prostate stroma highly expressed both caveolin-1 and cavin-1. Utilizing PC-3 cells as a suitable model for caveolin-1-positive advanced prostate cancer, we found that cavin-1 expression in PC-3 cells inhibits anchorage-independent growth, and reduces in vivo tumor growth and metastasis in an orthotopic prostate cancer xenograft mouse model. The expression of α-smooth muscle actin in stroma along with interleukin-6 (IL-6) in cancer cells was also decreased in tumors of mice bearing PC-3-cavin-1 tumor cells. To determine whether cavin-1 acts by neutralizing caveolin-1, we expressed cavin-1 in caveolin-1-negative prostate cancer LNCaP and 22Rv1 cells. Caveolin-1 but not cavin-1 expression increased anchorage-independent growth in LNCaP and 22Rv1 cells. Cavin-1 co-expression reversed caveolin-1 effects in caveolin-1-positive LNCaP cells. Taken together, these results suggest that caveolin-1 in advanced prostate cancer is present outside of caveolae, because of the lack of cavin-1 expression. Cavin-1 expression attenuates the effects of non-caveolar caveolin-1 microdomains partly via reduced IL-6 microenvironmental function. With circulating caveolin-1 as a potential biomarker for advanced prostate cancer, identification of the molecular pathways affected by cavin-1 could provide novel therapeutic targets.

Abstract 3040: Cavin-1 alters oncogenic effects of caveolin-1 microdomains in prostate cancer.

Abstract Caveolin-1 is associated with prostate cancer progression and has been suggested to be a biomarker and therapeutic target. Mature caveolin-1 resides in lipid raft domains at the plasma membrane, where it forms caveolae upon co-expression of cavin-1 (also known as PTRF; polymerase I and transcript release factor). In the absence of cavin-1, caveolin-1 does not form caveolae but are found on flat membrane. To determine if oncogenic caveolin-1 in prostate cancer is present in caveolae, we examined the relative expression of caveolin-1 and cavin-1 in normal, non-malignant and malignant prostate tissues. We found that caveolin-1 is induced in prostate cancer without cavin-1, an expression pattern mirror in the PC3 cell line. Previously we showed that expression of cavin-1 in PC3 cells recruits flat membrane caveolin-1 to caveolae and reduced transmigration. Here we report that cavin-1 expression reduces tumour size and metastasis of PC3 cells in vivo, using an orthotopic prostate cancer xenograft mouse model. To determine if cavin-1 acts by neutralizing oncogenic caveolin-1, we expressed cavin-1 in caveolin-1 negative LNCaP and 22Rv1 cells. While caveolin-1 over-expression increased anchorage-independent growth of LNCaP and 22Rv1 cells, cavin-1 over-expression had no effect. Furthermore, co-expression of cavin-1 in LNCaP+caveolin-1 cells reversed caveolin-1 effect. Taken together, these results suggest that caveolin-1 in prostate cancer is present outside of caveolae, and caveola formation by cavin-1 co-expression alters the oncogenic effect of non-caveolar caveolin-1 microdomains. Citation Format: Hyeongsun Moon, C Soon Lee, Sowmya Sharma, Kerry Inder, Debra Black, Kim-Anh Lê Cao, Clay Winterford, Patrick Ling, the Australian Prostate Cancer BioResource, David Craik, Robert Parton, Pamela Russell, Michelle Hill. Cavin-1 alters oncogenic effects of caveolin-1 microdomains in prostate cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3040. doi:10.1158/1538-7445.AM2013-3040

Phosphocaveolin-1 is a mechanotransducer that induces caveola biogenesis via Egr1 transcriptional regulation

Caveolin-1 (Cav1) is an essential component of caveolae whose Src kinase-dependent phosphorylation on tyrosine 14 (Y14) is associated with regulation of focal adhesion dynamics. However, the relationship between these disparate functions remains to be elucidated. Caveola biogenesis requires expression of both Cav1 and cavin-1, but Cav1Y14 phosphorylation is dispensable. In this paper, we show that Cav1 tyrosine phosphorylation induces caveola biogenesis via actin-dependent mechanotransduction and inactivation of the Egr1 (early growth response-1) transcription factor, relieving inhibition of endogenous Cav1 and cavin-1 genes. Cav1 phosphorylation reduces Egr1 binding to Cav1 and cavin-1 promoters and stimulates their activity. In MDA-231 breast carcinoma cells that express elevated levels of Cav1 and caveolae, Egr1 regulated Cav1, and cavin-1 promoter activity was dependent on actin, Cav1, Src, and Rho-associated kinase as well as downstream protein kinase C (PKC) signaling. pCav1 is therefore a mechanotransducer that acts via PKC to relieve Egr1 transcriptional inhibition of Cav1 and cavin-1, defining a novel feedback regulatory loop to regulate caveola biogenesis.

Loss of bladder smooth muscle caveolae in the aging bladder

Caveolae are specialized regions of the cell membrane that modulate signal transduction and alterations in these structures affect bladder smooth muscle (BSM) contraction. Since bladder dysfunctions are common in the elderly, we evaluated the effect of aging on the morphology of caveolae and caveolin protein expression in BSM. Caveolar morphology (number, size, and depth) in BSM was determined from electron microscopy images of young (10 weeks), adult (6-month old), and old (12-month old) rat urinary bladders. Changes in expression levels of caveolin proteins with age were investigated by Western blot and immunofluorescence microscopy. Caveolin-3 gene expression was determined by real-time RT-PCR in young and 19-month-old rat bladders. Twelve-month-old animals exhibited 50% fewer BSM caveolae compared to young (P < 0.01). The area of caveolae was significantly decreased at 6 and 12 months. Despite a decrease in the number of BSM caveolae at 12 months, the expression of caveolin-1 and cavin-1 were unaltered with age. In contrast, caveolin-2 and caveolin-3 protein expression and immunoreactivity were reduced in BSM at 6 and 12 months of age. Caveolin-3 gene expression was also downregulated at 19 months compared to young animals. Biological aging significantly decreases BSM caveolae number and morphology with associated selective alteration in caveolin protein expression. Since caveolae are protected membrane regions that regulate signal transduction, age-related alterations in caveolae and caveolin protein expression could alter BSM contractility resulting in bladder dysfunctions of the elderly.

P14. The number and location of vessels with decidual vasculopathy correlate with disease severity in preeclampsia

were observed (P > 0.05 for all) in the protein expression of Cav-1, Cavin-1 and eNOS between groups. Conclusion: The description of the mRNA and protein expression of Cavin-1 within the placenta is to our knowledge novel. Our findings provide evidence for a potential mechanistic pathway whereby a reduction in placental Cav-1 and Cavin-1 leads to chronic activation of eNOS within PE. The altered placental expression may serve as a compensatory mechanism to attenuate the characteristic vasoconstriction; conversely, it may be a consequence of the well recognised oxidative/nitrative stress state observed in PE. Clearly, these differences are not observed at the general protein level. However, distribution of co-localised eNOS and Cav-1 is very tissue-specific and immunohistochemistry is needed to identify alterations in the location and activity of the proteins through post-translational modifications.

P13. Alterations in placental expression of Caveolin-1, Cavin-1 and eNOS in women with pre-eclampsia

P13. Alterations in placental expression of Caveolin-1, Cavin-1 and eNOS in women with pre-eclampsia

Biochemical and functional correlates of an increased membrane density of caveolae in hypertrophic rat urinary bladder

Organ hypertrophy is often found to be associated with changes in the expression of caveolins and altered density of caveolae in the membrane. A plethora of signalling intermediaries are associated with caveolae and loss of caveolae has profound effects on contractility of the urinary bladder. We hypothesized that smooth muscle hypertrophy caused by bladder outflow obstruction (BOO) might lead to an altered caveola density with consequences for contractile regulation. Rat BOO for 6 weeks caused a 2.56-fold increase in the number of smooth muscle caveolae per μm membrane. No changes in the expression of caveolin-1 or cavin-1, normalized to β-actin were seen, but membrane area per unit muscle volume dropped to 0.346. Hypertrophy was associated with altered contraction in response to carbachol. The effect on contraction of cholesterol desorption, which disrupts lipid rafts and caveolae, was however not changed. Contraction in response to bradykinin resisted mβcd in control destrusor, but was inhibited by it after 6 weeks of obstruction. It is concluded that rat detrusor hypertrophy leads to an increased number of caveolae per unit membrane area. This change is due to a reduction of membrane area per volume muscle and it does not play a role for cholinergic activation, but promotes contraction in response to bradykinin after long-term obstruction.