Caveolin-1 Protein Research Articles

Nebulization of Hypoxic hUCMSC-EVs Attenuates Airway Epithelial Barrier Defects in Chronic Asthma Mice by Transferring CAV-1.

Nebulization of hypoxic human umbilical cord mesenchymal stem cell-derived extracellular vesicles (Hypo-EVs) can suppress airway inflammation and remodeling in a chronic asthmatic mouse; however, the exact mechanism remains unclear. Recently, airway epithelial barrier defects have been regarded as crucial therapeutic targets in asthma. The aim of this study was to investigate whether and how Hypo-EVs protect against the disruption of the airway epithelial barrier under asthmatic conditions. The therapeutic effects of Hypo-EVs on airway epithelial barrier defects were evaluated in ovalbumin (OVA)-induced asthmatic mice and in IL-4 and IL-13-induced HBE135-E6E7 cell models by detecting cell monolayer leakage and junctional protein expression. The protein levels in Hypo-EVs were determined by Western blotting, and a gene knockdown approach was used to investigate the biofactors in Hypo-EVs. Nebulization of Hypo-EVs directly alleviated airway epithelial barrier defects in asthmatic mice, as evidenced by colocalization with bronchial epithelial cells, decreased albumin concentration, and increased ZO-1 and E-cadherin expression. In vitro, Hypo-EV treatment dramatically rescued the increase in airway cell permeability, and upregulated the ZO-1 and E-cadherin protein expressions. Based on WB analysis, we found that caveolin-1 (CAV-1) was strongly enriched in Hypo-EVs. The knockdown of CAV-1 protein levels in Hypo-EVs significantly impaired Hypo-EV-mediated barrier protection in vitro and in vivo. Moreover, CAV-1 knockdown significantly abolished the beneficial effects of Hypo-EVs on airway inflammation and remodeling in asthmatic mice. In addition, we showed that IL-4/IL-13-induced airway epithelial barrier defects were mainly related to activation of STAT6 phosphorylation (p-STAT6), and overexpression of CAV-1 or Hypo-EV treatment inhibited the levels of p-STAT6 in IL-4/IL-13-induced HBE135-E6E7 cells. Nebulization of Hypo-EVs can attenuate airway epithelial barrier defects in asthma by delivering CAV-1 to inhibit p-STAT6 expression and may be used to treat other barrier defect diseases.

A water-soluble caveolin-1 peptide inhibits psoriasis-like skin inflammation by suppressing cytokine production and angiogenesis

The plasma membrane protein caveolin-1 (CAV-1) regulates signaling by inhibiting a wide range of kinases and other enzymes. Our previous study demonstrated that the downregulation of CAV-1 in psoriatic epidermal cells contributes to inflammation by enhancing JAK/STAT signaling, cell proliferation, and chemokine production. Administration of the CAV-1 scaffolding domain (CSD) peptide suppressed imiquimod (IMQ)-induced psoriasis-like dermatitis. To identify an optimal therapeutic peptide derived from CAV-1, we have compared the efficacy of CSD and subregions of CSD that have been modified to make them water soluble. We refer to these modified peptides as sCSD, sA, sB, and sC. In IMQ-induced psoriasis-like dermatitis, while all four peptides showed major beneficial effects, sB caused the most significant improvements of skin phenotype and number of infiltrating cells, comparable or superior to the effects of sCSD. Phosphorylation of STAT3 was also inhibited by sB. Furthermore, sB suppressed angiogenesis both in vivo in the dermis of IMQ-induced psoriasis mice and in vitro by blocking the ability of conditioned media derived from CAV-1-silenced keratinocytes to inhibit tube formation by HUVEC. In conclusion, sB had similar or greater beneficial effects than sCSD not only by cytokine suppression but by angiogenesis inhibition adding to its ability to target psoriatic inflammation.

Caveolin 1 in bovine liver is associated with fatty acid-induced lipid accumulation and the ER unfolded protein response: role in fatty liver development

Disruption of endoplasmic reticulum (ER) homeostasis, i.e., ER stress, is intrinsically linked with lipid metabolism disorders in dairy cows. Caveolin 1 (CAV1) is a ubiquitously-expressed membrane-associated scaffolding protein involved in regulating the secretory pathway within the ER. Whether inhibiting the activity of CAV1 affects the ER and its potential role in hepatic lipid deposition in dairy cows is unknown. Biopsies of liver tissue from Holstein cows (days in milk: median = 13 d, range = 5 to 21) diagnosed as healthy (n = 6, hepatic TAG levels < 1%, milk production: median = 38.9 kg/day, Interquartile range = 38.0 and 40.8) or suffering from fatty liver (n = 6, hepatic TAG levels > 5%, milk production: median = 36.6 kg/day, Interquartile range = 35.7 and 38.1) revealed that fatty liver was associated with lower abundance of CAV1 gene and protein, higher phosphorylation (p) levels of PERK and IRE1α, and increased abundance of ATF6, GRP78, CHOP protein, and several unfolded protein response (UPR) genes (ATF4, sXBP1, and GRP78). Proteins related to de novo fatty acid synthesis, including ACC1, SREBP-1c, PPARγ, and downstream targets genes of SREBP1 (ACACA and FASN) also had greater abundance. This in vivo analysis highlighted a mechanistic link between CAV1 protein abundance, ER stress, and lipid metabolism during fatty liver. A mechanistic study was then performed in vitro with primary hepatocytes isolated from 5 healthy calves (weight, 40-45 kg; 1 d old). Initially, hepatocytes were treated with FFA (1.2 mM) for 1, 3, 6, or 12 h. FFA treatment reduced CAV1 protein abundance linearly while it reduced abundance of ER stress-related proteins, p-IRE1α, p-PERK, GRP78, ATF6, and CHOP. Proteins related to de novo fatty acid synthesis (ACC1, SREBP-1c, PPARγ) also increased linearly, and lipid droplets accumulated progressively over time following FFA treatment. Subsequently, to assess the role of CAV1 in FFA-induced ER stress and de novo fatty acid synthesis, hepatocytes were transfected with pCMV-CAV1 (cattle)-3 × FLAG-Neo (pc-CAV1) plasmid to overexpress CAV1 or with siRNA to silence CAV1 (siCAV1) transcription. Overexpression of CAV1 alleviated ER stress by reducing levels of p-PERK and p-IRE1α, as well as the protein abundance of ATF6, GRP78, CHOP, and several UPR genes (GRP78, ATF4, and sXBP1). Similarly, CAV1 overexpression decreased protein abundance of ACC1, SREBP-1c, PPARγ, and downstream targets genes of SREBP1 (ACACA and FASN). Conversely, silencing CAV1 exacerbated FFA-induced ER stress and de novo fatty acid synthesis. Considering the negative role of FFA-induced ER stress on lipid accumulation in hepatocytes, a second in vitro experiment involved hepatocytes treated with 0.5 μg/mL tunicamycin (TM, a typical ER stress inducer) for 24 h with or without overexpressing CAV1 (pc-CAV1). Overexpressing caveolin 1 reversed TM-induced increases in mRNA and protein associated with ER stress and de novo fatty acid synthesis. Furthermore, use of hepatocytes transfected with pc-CAV1 for 48 h and subjected to co-immunoprecipitation revealed that CAV1 interacts with IRE1α and ATF6. Overall, the data suggest that CAV1 may help reduce hepatic ER stress and mitigate fatty acid synthesis by binding to and inhibiting IRE1α and ATF6 signaling.

Monochasma Savatieri Aqueous Extract inhibits Human Breast Cancer Cell Line Migration and Adhesion Without Generating Toxicity.

Monochasma savatieri, is a rare and endangered plant used to treat cancer in Chinese traditional medicine. To evaluate the anti-cancer activity of M. savatieri aqueous extract by determining its cytotoxicity, anti-migratory, and anti-adhesion effects on breast cancer cells. Cell viability, migration, adhesion, circularity, and cell cycle were evaluated by crystal violet (CV) staining, wound-healing, and transwell assays and flow cytometry in MCF7 and MDA-MB-231 cells. Caveolin-1, snail, vimentin and activated Erk and Akt expression were determined by western blot in MDA-MB-231 cells. Immunofluorescent assays confirmed caveolin-1 expression in MDA-MB-231 cells. Survival and cell cycle of MCF7 and MDA-MB-231 cells were not modified by doses up to 500 μg/mL of the extract. The extract inhibited cell migration and adhesion of MDA-MB-231 cells. When cells were exposed to the extract, there was a slight decrease in protein expression of factors related to epithelial-to-mesenchymal transition (snail and vimentin) and a strong decrease in the expression of the oncogenic membrane protein caveolin- 1. Furthermore, the levels of phosphorylated Erk and Akt were also decreased. The content of acteoside, a phenylpropanoid glycoside with reported anti-cancer activity present in M. savatieri, was almost 5 times as much as isoacteoside. M. savatieri possesses anti-cancer activity without exerting cytotoxicity on breast cancer cells. The extract exhibited anti-migratory and anti-adhesion effects on breast cancer cells by regulating Erk and Akt signaling pathways and the expression of caveolin-1. In addition, acteoside present in M. savatieri could be responsible for the observed effects.

Insights in caveolae protein structure arrangements and their local lipid environment.

Caveolae are 50-80 nm sized plasma membrane invaginations found in adipocytes, endothelial cells or fibroblasts. They are involved in endocytosis, lipid uptake and the regulation of the cellular lipid metabolism as well as sensing and adapting to changes in plasma membrane tension. Caveolae are characterized by their unique lipid composition and their specific protein coat consisting of caveolin and cavin proteins. Recently, detailed structural information was obtained for the major caveolae protein caveolin1 showing the formation of a disc-like 11-mer proteincomplex. Furthermore, the importance of the cavindisordered regions in the generation of cavin trimers and caveolae at the plasma membrane were revealed. Thus,finally, structural insights about the assembly of the caveolar coat can be elucidated. Here, we review recent developments in caveolae structural biology with regard to caveolae coat formation and caveolae curvature generation. Secondly, we discuss the importance of specific lipid speciesnecessary for caveolae curvature and formation. Inthe last years, it was shown that specifically sphingolipids, cholesterol and fatty acids can accumulate in caveolae invaginations and may drive caveolae endocytosis. Throughout, we summarize recent studies in the field and highlight future research directions.

High Caveolin-1 mRNA expression in triple-negative breast cancer is associated with an aggressive tumor microenvironment, chemoresistance, and poor clinical outcome.

Currently, there are few treatment-predictive and prognostic biomarkers in triple-negative breast cancer (TNBC). Caveolin-1 (CAV1) is linked to chemoresistance and several important processes involved in tumor progression and metastasis, such as epithelial-mesenchymal transition (EMT). Herein, we report that high CAV1 gene expression is an independent factor of poor prognosis in TNBC. CAV1 gene expression was compared across different molecular features (e.g., PAM50 subtypes). CAV1 expression was assessed in relation to clinical outcomes using Cox regression adjusted for clinicopathological predictors. Differential gene expression and gene set enrichment analyses were applied to compare high- and low-expressing CAV1 tumors. Tumor microenvironment composition of high- and low-expressing CAV1 tumors was estimated using ECOTYPER. Tumor tissue microarrays were used to evaluate CAV1 protein levels in stromal and malignant cells. In the SCAN-B (n = 525) and GSE31519 (n = 327) cohorts, patients with CAV1-high tumors had an increased incidence of early recurrence adjusted HR 1.78 (95% CI 1.12-2.81) and 2.20 (95% CI 1.39-3.47), respectively. In further analysis, high CAV1 gene expression was associated with a molecular profile indicating altered metabolism, neovascularization, chemoresistance, EMT, suppressed immune response, and active tumor microenvironment. Protein levels of CAV1 in malignant and stromal cells were not correlated with CAV1 gene expression. CAV1 gene expression in TNBC is a biomarker that merits further investigation in clinical trials and as a therapeutic target.

Abstract 3132: Examining The Role Of The Lung Endothelial Cell Anti-apoptotic Protein C-iap2 In Schistosomiasis-associated Pulmonary Hypertension

Introduction: Schistosomiasis-associated Pulmonary Hypertension (Sch-PH) is the most common form of group I PH worldwide and remains with no targeted therapy. Previously, we observed that the loss of the anti-inflammatory protein caveolin-1 (Cav-1) in lung endothelial cells (EC) contributed to the survival of the abnormal EC phenotype in Sch-PH. Abnormal cell survival has been associated with some members of the inhibitor of apoptosis protein (IAP) family, but their role in Sch-PH is unknown. Hypothesis: The major etiological agent of Sch-PH, i.e., S. mansoni , may contribute to the abnormal lung EC phenotype via altered IAP family expression, specifically the inducible member c-IAP2. Methods/Methods: To test this hypothesis, we first quantified constitutive c-IAP1 and inducible c-IAP2 expression on lung samples from male and female control and pre-clinical S. mansoni egg-exposed mice (240 eggs/gram body weight intraperitoneally followed by intravenous injection of 175 eggs/gram body weight). Then, the specific contribution of EC-c-IAP2 expression to the progression of the disease was evaluated in our new mouse model ( Cdh5.CreERT2;cIAP1 -/- ,cIAP2 fl/fl - Cdh5.CreERT2;cIAP1 +/- ,cIAP2 +/fl ). EC- Cav1 -/- mice were also evaluated to test the contribution of EC-Cav-1 to lung c-IAP2 expression. Results/Discussion: Western blot and immunohistochemistry analysis revealed a reduction in c-IAP2 expression in the whole lung tissue of S. mansoni egg-exposed mice compared to controls (1.21 ± 0.12; 0.88 ± 0.06, control and egg-exposed mice respectively; p&lt;0.05; n=6). No difference was observed in c-IAP1 expression. Preliminary data indicate that genetic ablation of c-IAP2 in EC heterozygous mice promoted a mild increase in microvascular thickness and area in Masson’s Trichrome -stained lung sections. Consistent with our previous findings, c-IAP2 expression was also significantly impaired when Cav-1 expression was absent in lung ECs, suggesting that EC-Cav-1 may contribute to reduced lung c-IAP2 expression, leading to the severe vascular remodeling that underlies the development of Sch-PH. Conclusion: Our data is uncovering whether c-IAP2 expression is a novel and specific molecular target for future therapeutic approaches against chronic Sch-PH.

Exosomal Prostate-Specific Membrane Antigen (PSMA) and Caveolin-1 as Potential Biomarkers of Prostate Cancer-Evidence from Serbian Population.

Prostate-specific membrane antigen (PSMA) and caveolin-1 are membrane proteins that are overexpressed in prostate cancer (PCa) and are involved in tumor growth and increase in aggressiveness. The aim of the present study is therefore to evaluate PSMA and caveolin-1 proteins from plasma exosomes as effective liquid biopsy biomarkers for PCa. This study included 39 patients with PCa and 33 with benign prostatic hyperplasia (BPH). The shape and size of the exosomes were confirmed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analysis. Immunogold analysis showed that PSMA is localized to the membrane of exosomes isolated from the plasma of both groups of participants. The relative protein levels of PSMA and caveolin-1 in the plasma exosomes of PCa and BPH patients were determined by Western blot analysis. The relative level of the analyzed plasma exosomal proteins was compared between PCa and BPH patients and the relevance of the exosomal PSMA and caveoin-1 level to the clinicopathological parameters in PCa was investigated. The analysis performed showed an enrichment of exosomal PSMA in the plasma of PCa patients compared to the exosomes of men with BPH. The level of exosomal caveolin-1 in plasma was significantly higher in PCa patients with high PSA levels, clinical-stage T3 or T4 and in the group of PCa patients with aggressive PCa compared to favorable clinicopathological features or tumor aggressiveness. Plasma exosomes may serve as a suitable object for the identification of potential biomarkers for the early diagnosis and prognosis of PCa as well as carriers of therapeutic agents in precision medicine of PCa treatment.

Cholesterol depletion induces mesenchymal properties in oral squamous cell carcinoma cell line.

Cholesterol in cell membranes is crucial for cell signaling, adhesion, and migration. Membranes feature cholesterol-rich caveolae with caveolin proteins, playing roles in epithelial-mesenchymal transition and cancer progression. Despite elevated cholesterol levels in tumors, its precise function and the effects of its depletion in oral squamous cell carcinoma remain unclear. The aim of this study was to evaluate the influence of cholesterol depletion in oral squamous cell carcinoma cell line and epithelial-mesenchymal transition process. Cholesterol depletion was induced on SCC-9 cells by methyl-β-cyclodextrin and cell viability, proliferation, apoptosis, and colony formation capacities were evaluated. Gene and protein expressions were evaluated by reverse transcription polymerase chain reaction (RT-qPCR) and Western Blot, respectively, and cell sublocalization was assessed by immunofluorescence. Cholesterol depletion resulted in alteration of oral squamous cell carcinoma cell morphology at different concentrations of methyl-β-cyclodextrin, as well as decreased cell proliferation and viability rates. Analysis of CAV1 transcript expression revealed increased gene expression in the treated SCC-9 during the 24 h period, at different concentrations of methyl-β-cyclodextrin: 5 , 7.5, 10, and 15 mM, in relation to parental SCC-9. CAV1 protein expression was increased, with subsequent dose-dependent decrease. A statistically significant difference was observed in samples treated with 5 mM of methyl-β-cyclodextrin (p = 0.02, Kruskal-Wallis test). The immunofluorescence assay showed lower cytoplasmic and membrane labeling intensity in the treated samples for CAV1. These findings indicate the modulation of cholesterol as a possible mechanism underlying the regulation of these molecules and activation of epithelial-mesenchymal transition in oral squamous cell carcinoma.

Cysteine post-translational modifications regulate protein interactions of caveolin-3.

Caveolae are small flask-shaped invaginations of the surface membrane which are proposed to recruit and co-localize signaling molecules. The distinctive caveolar shape is achieved by the oligomeric structural protein caveolin, of which three isoforms exist. Aside from the finding that caveolin-3 is specifically expressed in muscle, functional differences between the caveolin isoforms have not been rigorously investigated. Caveolin-3 is relatively cysteine-rich compared to caveolins 1 and 2, so we investigated its cysteine post-translational modifications. We find that caveolin-3 is palmitoylated at 6 cysteines and becomes glutathiolated following redox stress. We map the caveolin-3 palmitoylation sites to a cluster of cysteines in its C terminal membrane domain, and the glutathiolation site to an N terminal cysteine close to the region of caveolin-3 proposed to engage in protein interactions. Glutathiolation abolishes caveolin-3 interaction with heterotrimeric G protein alpha subunits. Our results indicate that a caveolin-3 oligomer contains up to 66 palmitates, compared to up to 33 for caveolin-1. The additional palmitoylation sites in caveolin-3 therefore provide a mechanistic basis by which caveolae in smooth and striated muscle can possess unique phospholipid and protein cargoes. These unique adaptations of the muscle-specific caveolin isoform have important implications for caveolar assembly and signaling.

Dysregulated SYVN1 promotes CAV1 protein ubiquitination and accentuates ischemic stroke

BackgroundStroke is a major cause of death and severe disability, and there remains a substantial need for the development of therapeutic agents for neuroprotection in acute ischemic stroke (IS) to protect the brain against damage before and during recanalization. Caveolin-1 (CAV1), an integrated protein that is located at the caveolar membrane, has been reported to exert neuroprotective effects during IS. Nevertheless, the mechanism remains largely unknown. Here, we explored the upstream modifiers of CAV1 in IS. MethodsE3 ubiquitin ligases of CAV1 that are differentially expressed in IS were screened using multiple databases. The transcription factor responsible for the dysregulation of E3 ubiquitin-protein ligase synoviolin (SYVN1) in IS was predicted and verified. Genetic manipulations by lentiviral vectors were applied to investigate the effects of double-strand-break repair protein rad21 homolog (RAD21), SYVN1, and CAV1 in a middle cerebral artery occlusion (MCAO) mouse model and mouse HT22 hippocampal neurons induced by oxygen-glucose deprivation (OGD). ResultsSYVN1 was highly expressed in mice with MCAO, and knockdown of SYVN1 alleviated IS injury in mice, as evidenced by limited infarction volume, the lower water content in the brain, and repressed apoptosis and inflammatory response. RAD21 inhibited the transcription of SYVN1, thereby reducing the ubiquitination modification of CAV1. Overexpression of RAD21 elicited a neuroprotective role as well in mice with MCAO and HT22 induced with OGD, which was overturned by SYVN1. ConclusionTranscriptional repression of SYVN1 by RAD21 alleviates IS in mice by reducing ubiquitination modification of CAV1.

Human Adenovirus Entry and Early Events during Infection of Primary Murine Neurons: Immunofluorescence Studies In Vitro.

Human adenovirus (HAdV) is a common pathogen, which can lead to various clinical symptoms and-in some cases-central nervous system (CNS) dysfunctions, such as encephalitis and meningitis. Although the initial events of virus entry have already been identified in various cell types, the mechanism of neuronal uptake of adenoviruses is relatively little understood. The aim of this study was to investigate early events during adenoviral infection, in particular to determine the connection between cellular coxsackievirus and adenovirus receptor (CAR), clathrin, caveolin, and early endosomal proteins (EEA1 and Rab5) with the entry of HAdVs into primary murine neurons in vitro. An immunofluorescence assay and confocal microscopy analysis were carried out to determine HAdV4, 5, and 7 correlation with CAR, clathrin, caveolin, and early endosomal proteins in neurons. The quantification of Pearson's coefficient between CAR and HAdVs indicated that the HAdV4 and HAdV5 types correlated with CAR and that the correlation was more substantial for HAdV5. Inhibition of clathrin-mediated endocytosis using chlorpromazine limited the infection with HAdV, whereas inhibition of caveolin-mediated endocytosis did not affect virus entry. Thus, the entry of tested HAdV types into neurons was most likely associated with clathrin but not caveolin. It was also demonstrated that HAdVs correlate with the Rab proteins (EEA1, Rab5) present in early vesicles, and the observed differences in the manner of correlation depended on the serotype of the virus. With our research, we strove to expand knowledge regarding the mechanism of HAdV entry into neurons, which may be beneficial for developing potential therapeutics in the future.

Allosteric inhibitor of SHP2 enhances macrophage endocytosis and bacteria elimination by increasing caveolae activation and protects against bacterial sepsis

The uncontrolled bacterial infection-induced cytokine storm and sequential immunosuppression are commonly observed in septic patients, which indicates that the activation of phagocytic cells and the efficient and timely elimination of bacteria are crucial for combating bacterial infections. However, the role of dysregulated immune cells and their disrupted function in sepsis remains unclear. Here, we found that macrophages exhibited the impaired endocytosis capabilities in sepsis by Single-cell RNA sequencing and bulk RNA sequencing. Caveolae protein Caveolin-1 (Cav-1) of macrophages was inactivated by SHP2 rapidly during Escherichia coli (E.coli) infection. Allosteric inhibitor of SHP2 effectively maintains Cav-1 phosphorylation to enhance macrophage to endocytose and eliminate bacteria. Additionally, TLR4 endocytosis of macrophage was also enhanced upon E.coli infection by SHP099, inducing an increased and rapidly resolved inflammatory response. In vivo, pretreatment or posttreatment with inhibitor of SHP2 significantly reduced the bacterial burden in organs and mortality of mice subjected E.coli infection or CLP-induced sepsis. The cotreatment of inhibitor of SHP2 with an antibiotic conferred complete protection against mortality in mice. Our findings suggest that Cav-1-mediated endocytosis and bacterial elimination may play a critical role in the pathogenesis of sepsis, highlighting inhibitor of SHP2 as a potential therapeutic agent for sepsis.

Abstract A006: Spatial localization of Caveolin-1 protein in triple negative breast cancer is related to different molecular features

Abstract Background: Triple negative breast cancer (TNBC) is an aggressive and heterogeneous form of breast cancer with few targeted therapies and clinically used biomarkers. Caveolin-1 (CAV1) is a marker of stromal activation and vascularization. Molecular features of the tumor microenvironment (TME), important for tumor metastasis, may improve precision oncology in TNBC. CAV1 protein levels have previously been reported as a potential biomarker in breast cancer depending on their localization. Therefore, we aimed to investigate CAV1 protein levels in malignant and stromal cells of TNBC and their relation to CAV1 gene expression, clinicopathological factors, and molecular features. Methods: Tumor-specific CAV1 protein levels were evaluated with immunohistochemistry in malignant and stromal cells in tumor tissue microarrays from a cohort of 242 TNBC patients (inclusion 2010-2015, Sweden) from SCAN-B (NCT03758976). The protein levels of CAV1 in malignant and stromal cells were dichotomized as ‘strong’ (1) vs ‘negative to moderate’ (0) The CAV1 categories in malignant and stromal cells, respectively, were combined to create a joint CAV1 status with four categories: malignant/stromal cells, 0/0, 0/1, 1/0, and 1/1. Gene expression profiles from massive parallel paired-end sequencing of mRNA (RNA-seq) were available for all the tumors and from which PAM50 category and TNBC subtype were assigned. CAV1 status in malignant and stromal cells in relation to clinicopathological factors was analyzed using Chi-Square test. CAV1 mRNA expression in relation to CAV1 status in malignant and stromal cells was evaluated using Kruskal-Wallis test. Results: CAV1 status could be evaluated in 231/242 tumors. Strong CAV1 staining in malignant cells was associated with higher histological grade but no axillary lymph node involvement (both P &amp;lt;0.007). In contrast, strong CAV1 staining in stromal cells was associated with lower histological grade but axillary lymph node involvement (both P &amp;lt;0.001). Strong CAV1 staining in stromal cells was also associated with higher age at diagnosis (P =0.025). With regards to PAM50 subtypes, CAV1 in malignant cells was positively associated with the basal subtype while CAV1 in malignant cells was positively associated with the HER2 enriched subtype (P &amp;lt;0.001). Depending on localization, CAV1 expression was associated with different TNBCsubtypes. CAV1 in malignant cells was positively associated with the mesenchymal and negatively associated with the immunomodulatory subtype (P &amp;lt;0.001). CAV1 in stromal cells was positively associated with the luminal androgen (LAR) subtype (P &amp;lt;0.001). Neither CAV1 protein levels in malignant cells nor in stromal cells were correlated with CAV1 gene expression in the tumors, and the combined CAV1 status was not associated with CAV1 gene expression. Conclusion: CAV1 protein levels in malignant cells were related to different molecular features of TNBC compared to CAV1 protein levels in stromal cells. The results suggest that depending on localization, CAV1 protein levels function as two distinct biomarkers. Citation Format: Christopher Godina, Somayeh Khazaei, Mattias Belting, Johan Vallon-Christersson, Björn Nodin, Karin Jirström, Karolin Isaksson, Ana Bosch, Helena Jernström. Spatial localization of Caveolin-1 protein in triple negative breast cancer is related to different molecular features [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr A006.

Interleukin 17A Contributes to Blood-Brain Barrier Disruption of Hypothalamic Paraventricular Nucleus in Rats With Myocardial Infarction.

Elevated inflammatory cytokines in the periphery have been identified as active contributors to neuroinflammation and sympathetic overactivity in heart failure (HF). Yet, the exact mechanisms by which these cytokines breach the blood-brain barrier (BBB) to exert their effects on the brain remain elusive. Interleukin 17A has been linked to BBB disruption in various neurologic disorders, and its levels were significantly augmented in circulation and the brain in HF. The present study aimed to determine whether the BBB integrity was compromised within the hypothalamic paraventricular nucleus (PVN), and if so, whether interleukin 17A contributes to BBB disruption in myocardial infarction-induced HF. Male Sprague-Dawley rats underwent coronary artery ligation to induce HF or sham surgery. Some HF rats received bilateral PVN microinjections of an interleukin 17 receptor A small interfering RNA or a scrambled small interfering RNA adeno-associated virus. Four weeks after coronary artery ligation, the permeability of the BBB was evaluated by intracarotid injection of fluorescent dyes (fluorescein isothiocyanate-dextran 10 kDa+rhodamine-dextran 70 kDa). Compared with sham-operated rats, HF rats exhibited an elevated extravasation of fluorescein isothiocyanate-dextran 10 kDa within the PVN but not in the brain cortex. The plasma interleukin 17A levels were positively correlated with fluorescein isothiocyanate 10 kDa extravasation in the PVN. The expression of caveolin-1, a transcytosis marker, was augmented, whereas the expression of tight junction proteins was diminished in HF rats. Interleukin 17 receptor A was identified within the endothelium of PVN microvessels. Treatment with interleukin 17 receptor A small interfering RNA led to a significant attenuation of fluorescein isothiocyanate 10 kDa extravasation in the PVN and reversed expression of caveolin-1 and tight junction-associated proteins in the PVN. Collectively, these data indicate that BBB permeability within the PVN is enhanced in HF and is likely attributable to increased interleukin 17A/interleukin 17 receptor A signaling in the BBB endothelium, by promoting caveolar transcytosis and degradation of tight junction complexes.

Caveolae and caveolin-1 as targets of dietary polyphenols for protection against vascular endothelial dysfunction.

Caveolae, consisting of caveolin-1 proteins, are ubiquitously present in endothelial cells and contribute to normal cardiovascular functions by acting as a platform for cellular signaling pathways as well as transcytosis and endocytosis. However, caveolin-1 is thought to have a proatherogenic role by inhibiting endothelial nitric oxide synthase activity and Nrf2 activation, or by promoting inflammation through NF-κB activation. Dietary polyphenols were suggested to exert anti-atherosclerotic effects by a mechanism involving the inhibition of endothelial dysfunction, by which they can regulate redox-sensitive signaling pathways in relation to NF-κB and Nrf2 activation. Some monomeric polyphenols and microbiota-derived catabolites from monomeric polyphenols or polymeric tannins might be responsible for the inhibition, because they can be transferred into the circulation from the digestive tract. Several polyphenols were reported to modulate caveolin-1 expression or its localization in caveolae. Therefore, we hypothesized that circulating polyphenols affect caveolae functions by altering its structure leading to the release of caveolin-1 from caveolae, and attenuating redox-sensitive signaling pathway-dependent caveolin-1 overexpression. Further studies using circulating polyphenols at a physiologically relevant level are necessary to clarify the mechanism of action of dietary polyphenols targeting caveolae and caveolin-1.

Chronic exposure to polystyrene nanoplastics induces intestinal mechanical and immune barrier dysfunction in mice

Micro(nano)plastics are prevalent in the environment, and prolonged exposure to them represents a threat to human health. The goal of this study is to assess the health risk of long-term exposure to nanoplastics (NPs) at environmental concentrations on the intestinal mechanical and immune barrier in mice. In this study, mice were provided drinking water containing polystyrene NPs (PS-NPs; 0.1, 1, and 10 mg·L−1) for 32 consecutive weeks. The levels of endocytosis proteins caveolin and clathrin and of tight junctional proteins claudin-1, occludin, and ZO-1, and morphological changes, proportion of lymphocytes B in MLNs and lymphocytes T in IELs and LPLs were determined by immunohistochemistry, hematoxylin–eosin, and flow cytometry assays in the intestinal tissues of mice at 28 weeks. The activities or concentrations of ROS, SOD, MDA, and GSH-Px and inflammatory factors (IL-1β, IL-6, and TNF-α) in the intestinal tissues of mice were measured by ELISA at 12, 16, 20, 24, and 32 weeks. Compared with the control group, oral ingested PS-NPs entered the intestinal tissues of mice and upregulated expression levels of the clathrin and caveolin. The intestinal tissue structure of mice in the PS-NPs (1 and 10 mg·L−1) exposure groups showed significant abnormalities, such as villus erosion, decreased of crypts numbers and large infiltration of inflammatory cells. Exposure to 0.1 mg·L−1 PS-NPs decreased occludin protein levels, but not claudin-1 and ZO-1 levels. The levels of these three tight junction proteins decreased significantly in the 1 and 10 mg·L−1 PS-NPs exposed groups. Exposure to PS-NPs led to a significant time- and dose-dependent increase in ROS and MDA levels, and concurrently decreased GSH-Px and SOD contents. Exposure to PS-NPs increased the proportion of B cells in MLNs, and decreased the proportion of CD8+ T cells in IELs and LPLs. The levels of pro-inflammatory cytokines IL-6, TNF-α and IL-1β were markedly elevated after PS-NPs exposure. Long-term PS-NPs exposure impaired intestinal mechanical and immune barrier, and indicate a potentially significant threat to human health.

YuPingFeng (YPF) upregulates caveolin-1 (CAV1) to alleviate pulmonary fibrosis through the TGF-β1/Smad2 pathway

Ethnopharmacological relevanceTraditional Chinese medicine (TCM) is considered a valuable asset in China's medical tradition. YPF is a classic prescription that has been derived from the "Jiu Yuan Fang" formula and consists of three herbs: Huangqi (Astragalus membranaceus Bunge), Baizhu (Atractylodes rubra Dekker), and Fangfeng (Saposhnikovia divaricata (Turcz.) Schischk). This prescription is widely acclaimed for its exceptional pharmacological properties, including potent antioxidant effects, hormone regulation, and immune modulation effects. Aim of the studyPrevious research provides evidence suggesting that YPF may have therapeutic effects on pulmonary fibrosis. Further exploration is essential to confirm its effectiveness and elucidate the fundamental processes. Materials and methodsFirst, the active components and target genes of YPF were extracted from the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database. Next, the GSE53845 dataset, which contains information on pulmonary fibrosis, was downloaded from the GEO database. Network informatics methods was then be utilized to identify target genes associated with pulmonary fibrosis. A YPF-based network of protein-protein interactions was constructed to pinpoint possible target genes for pulmonary fibrosis treatment. Additionally, an in vitro model of pulmonary fibrosis induced by bleomycin (BLM) was established to further investigate and validate the possible mechanisms underlying the effectiveness of YPF. ResultsIn this study, a total of 24 active ingredients of YPF, along with 178 target genes associated with the treatment, were identified. Additionally, 615 target genes related to pulmonary fibrosis were identified. Functional enrichment analysis revealed that 18 candidate genes (CGs) exhibited significant responses to tumor necrosis factor, NF-kB survival signaling, and positive regulation of apoptosis processes. Among these CGs, CAV1, VCAM1, and TP63 were identified as key target genes. Furthermore, cell experiments confirmed that the expression of CAV1 protein and RNA expression was increased in pulmonary fibrosis, but significantly decreased after treatment with YPF. Additionally, the expression of pSmad2, α-SMA, TGF-β1, and TNF-α was also decreased following YPF treatment. ConclusionsNetwork pharmacology analysis revealed that YPF exhibits significant potential as a therapeutic intervention for pulmonary fibrosis by targeting various compounds and pathways. This study emphasizes that the efficacy of YPF in treating pulmonary fibrosis may be attributed to its ability to up-regulate CAV1 expression and inhibiting pulmonary fibrosis via modulation of the TGF-β1/Smad2 signaling pathway. These findings underscore the promising role of YPF and its ability to potentially alleviate pulmonary fibrosis.

Caveolin-3 negatively regulates endocytic recycling of cardiac KATP channels.

Sarcolemmal ATP-sensitive potassium (KATP) channels play a vital role in cardioprotection. Cardiac KATP channels are enriched in caveolae and physically interact with the caveolae structural protein caveolin-3 (Cav3). Disrupting caveolae impairs the regulation of KATP channels through several signaling pathways. However, the direct functional effect of Cav3 on KATP channels is still poorly understood. Here, we used the cardiac KATP channel subtype, Kir6.2/SUR2A, and showed that Cav3 greatly reduced KATP channel surface density and current amplitude in a caveolae-independent manner. A screen of Cav3 functional domains revealed that a 25 amino acid region in the membrane attachment domain of Cav3 is the minimal effective segment (MAD1). The peptide corresponding to the MAD1 segment decreased KATP channel current in a concentration-dependent manner with an IC50 of ∼5 μM. The MAD1 segment prevented KATP channel recycling, thus decreasing KATP channel surface density and abolishing the cardioprotective effect of ischemic preconditioning. Our research identified the Cav3 MAD1 segment as a novel negative regulator of KATP channel recycling, providing pharmacological potential in the treatment of diseases with KATP channel trafficking defects.NEW & NOTEWORTHY Cardiac KATP channels physically interact with caveolin-3 in caveolae. In this study, we investigated the functional effect of caveolin-3 on KATP channel activity and identified a novel segment (MAD1) in the C-terminus domain of Caveolin-3 that negatively regulates KATP channel surface density and current amplitude by impairing KATP channel recycling. The peptide corresponding to the MAD1 segment abolished the cardioprotective effect of ischemic preconditioning.

Caveolin-1 promotes glioma progression and maintains its mitochondrial inhibition resistance

BackgroundGlioma is a lethal brain cancer and lacking effective therapies. Challenges include no effective therapeutic target, intra- and intertumoral heterogeneity, inadequate effective drugs, and an immunosuppressive microenvironment, etc. Deciphering the pathogenesis of gliomas and finding out the working mechanisms are urgent and necessary for glioma treatment. Identification of prognostic biomarkers and targeting the biomarker genes will be a promising therapy.MethodsFrom our RNA-sequencing data of the oxidative phosphorylation (OXPHOS)-inhibition sensitive and OXPHOS-resistant cell lines, we found that the scaffolding protein caveolin 1 (CAV1) is highly expressed in the resistant group but not in the sensitive group. By comprehensive analysis of our RNA sequencing data, Whole Genome Bisulfite Sequencing (WGBS) data and public databases, we found that CAV1 is highly expressed in gliomas and its expression is positively related with pathological processes, higher CAV1 predicts shorter overall survival.ResultsFurther analysis indicated that (1) the differentiated genes in CAV1-high groups are enriched in immune infiltration and immune response; (2) CAV1 is positively correlated with tumor metastasis markers; (3) the methylation level of CAV1 promoters in glioma group is lower in higher stage than that in lower stage; (4) CAV1 is positively correlated with glioma stemness; (5) higher expression of CAV1 renders the glioma cells’ resistant to oxidative phosphorylation inhibitors.ConclusionTherefore, we identified a key gene CAV1 and deciphered its function in glioma progression and prognosis, proposing that CAV1 may be a therapeutic target for gliomas.Graphical