Cav-1 (Caveolin-1) Deficiency Increases Autophagy in the Endothelium and Attenuates Vascular Inflammation and Atherosclerosis

CAVIN-2 positively correlates with diabetic PAD and promotes LDL transcytosis by inhibiting eNOS activation

OBJECTIVE

Caveolae are closely linked to the onset and progression of atherosclerosis. The pivotal involvement of caveolin-1 (CAV1) within the caveolae in atherosclerosis development has been consistently supported. However, the potential contributions of additional caveolae proteins to atherosclerosis necessitate further exploration. Therefore, this research aimed to afford clinical evidence linking CAVIN-2 to diabetic peripheral artery disease (PAD) and its role in low-density lipoprotein (LDL) transcytosis.

METHODS

Blood samples were collected from a total of 115 participants, including 36 patients without diabetes (ND), 26 patients with type 2 diabetes mellitus (T2DM), and 53 patients with T2DM and PAD (DM-PAD). The plasma levels of CAV1, CAVIN-1, and CAVIN-2 were measured by ELISA. The correlation between CAV1, CAVIN-1, CAVIN-2, and diabetic PAD was examined using Spearman correlation analysis. The predictive effect of CAV1 and CAVIN-2 were analyzed by receiver operating characteristic (ROC) curves. Cellular experiments were used to investigate the effect and mechanism of CAVIN-2 on LDL transcytosis.

RESULTS

Elevated CAV1 and CAVIN-2 levels were observed in T2DM and DM-PAD groups, with a positive correlation to DM-PAD and PAD severity. Both CAV1 and CAVIN-2 emerged as predictors of DM-PAD. In vitro, CAVIN-2 knockdown decreased LDL transcytosis, while CAVIN-2 overexpression increased it. Additionally, CAVIN-2 was found to inhibit eNOS activation and nitric oxide (NO) production, thereby promoting LDL transcytosis and atherosclerosis progression.

CONCLUSION

CAVIN-2 was positively correlated with DM-PAD and promoted LDL transcytosis through the inhibition of eNOS activation, contributing to atherosclerosis development. This study provided clinical evidence linking CAVIN-2 to diabetic PAD and suggested its potential as a biomarker for disease progression.

CAV1 Exacerbates Renal Tubular Epithelial Cell Senescence by Suppressing CaMKK2/AMPK-Mediated Autophagy

Renal proximal tubular epithelial cell (PTEC) senescence and defective autophagy contribute to kidney aging, but the mechanisms remain unclear. Caveolin-1 (CAV1), a crucial component of cell membrane caveolae, regulates autophagy and is associated with cellular senescence. However, its specific role in kidney aging is poorly understood. In this study, we generated Cav1 gene knockout mice and induced kidney aging using D-galactose (D-gal). The results showed that CAV1 expression increased in the renal cortex of the aging mice, which was accompanied by exacerbated renal interstitial fibrosis, elevated levels of senescence-associated proteins γH2AX and p16INK4a, and increased β-galactosidase activity. Moreover, autophagy and AMPK phosphorylation in PTECs were reduced. These phenotypes were partially reversed in D-gal-induced Cav1 knockout mice. Similar results were observed in D-gal-induced human proximal tubular epithelial (HK-2) cells, but these effects were blocked when AMPK activation was inhibited. Additionally, in CaMKK2 knockdown HK-2 cells, siCAV1 failed to promote AMPK phosphorylation, whereas this effect persisted when STK11 was knocked down. Besides, we examined the phosphorylation of CaMKK2 and found that siCAV1 increased its activity. Given that CaMKK2 activity is affected by intracellular Ca2+, we examined Ca2+ levels in HK-2 cells and found that D-gal treatment reduced intracellular Ca2+ concentration, but CAV1 knockdown did not alter these levels. Through GST pull-down assays, we demonstrated a direct interaction between CAV1 and CaMKK2. In conclusion, these findings suggest that CAV1 exacerbates renal tubular epithelial cell senescence by directly interacting with CaMKK2, suppressing its activity and AMPK-mediated autophagy via a Ca2+-independent pathway.

High glucose-induced alternative splicing of MEF2D in macrophages promotes vascular chronic inflammation in type 2 diabetes mellitus by mediating M1 macrophage polarization

OBJECTIVES

To investigate the effects of a high-glucose environment in type 2 diabetes mellitus (T2DM) on Myocyte enhancer factor 2d (MEF2D) selective splicing and its impact on the disease process and mechanism.

METHODS

Human monocyte (THP-1) cells were induced into macrophages with phorbol 12-myristate 13-acetate (PMA), and treated with high glucose for 24 h. PCR confirmed MEF2D splicing products. MEF2D or MEF2D-AS overexpression vectors were transfected into macrophages, and ELISA detected inflammatory factors; flow cytometry analyzed MI/M2 phenotypes; and levels of LC3, PI3K, and LAMP2 were measured. Autophagic flux detection; co-immunoprecipitation detected MEF2D and KCNMA1 interaction; WB and RT-qPCR assessed KCNMA1 expression. Macrophages co-cultured with endothelial cells were analyzed by ELISA for vascular inflammation factors MMP-9, Cys-C, and hsCRP.

RESULTS

High glucose-induced alternative splicing of MEF2D at 86-132 aa. MEF2D-AS group showed higher inflammatory factors, increased M1 phenotype, lower autophagy gene expression, and higher vascular inflammation factors compared to MEF2D group. Autophagy activator Rapamycin or KCNMA1 overexpression reversed these effects. MEF2D targeted KCNMA1, and MEF2D-AS overexpression led to decreased KCNMA1, increased inflammatory factors, M1 polarization, autophagy inhibition, and higher vascular inflammation factors.

CONCLUSION

High glucose induces MEF2D alternative splicing in macrophages, inhibiting autophagy and promoting M1 polarization via KCNMA1 down-regulation, thus promoting chronic inflammation in T2DM vessels.

Lysyl-tRNA synthetase 1 promotes atherogenesis via autophagy-related secretion and inflammation

Lysyl-tRNA synthetase 1 (KARS1), an aminoacyl-tRNA synthetase, was recently identified as a secreted pro-inflammatory agent. However, the vascular secretion and functions of KARS1 have not been characterized. This study investigated the secretion mechanisms of KARS1 and explored its functional roles in vascular biology. We found that KARS1 expression was upregulated by oscillatory shear stress, an atherogenic factor, suggesting the presence of free KARS1 dissociated from aminoacyl-tRNA synthetase complexes. Moreover, in the presence of Ca2+, serum starvation triggered free cytosolic KARS1 release from endothelial cells via secretory autophagy. Both phosphatidylinositol 3-phosphate kinase and caveolin-1 were either supplementary or essential for KARS1 secretion. Secreted KARS1 co-localized in the exosome fraction of post-culture media and was externally exposed. Further, secreted KARS1 inhibited shear-induced activation of various signaling molecules, including extracellular signal-regulated kinase, protein kinase B, and endothelial nitric oxide synthetase. Secreted KARS1 in atherosclerotic plaques also acted as an atherogenic or proinflammatory autocrine/paracrine molecule. Additionally, KARS1 participated in vessel alteration. Collectively, these findings describe novel vascular features of KARS1 in response to shear stress, providing insights into shear stress-controlling mechanisms of the vascular system.

Inhibition of CAV1 attenuates diabetic cardiomyopathy through reducing ferroptosis via activating NRF2/GCLC signaling pathway

Background: Diabetic cardiomyopathy (DCM), a prevalent complication of diabetes, is a major cause of heart failure and death among patients with diabetes. However, the pathological mechanisms underlying the development of DCM remain unclear. This study aims to investigate the role and underlying mechanisms of caveolin-1 (CAV1) in DCM. Methods: DCM model was established in vivo through intraperitoneal injection of streptozotocin in mice and in vitro through high-glucose (HG) treatment in neonatal rat ventricular myocytes (NRVMs). CAV1-knockout (CAV1-KO) and overexpression (by injecting adeno-associated virus 9 (AAV9) encoding CAV1) mice were utilized to explore the role of CAV1 in DCM. Nuclear factor erythroid 2-related factor 2 (NRF2)-KO and AAV9-NRF2 mice and ML385 (an NRF2 inhibitor) were used to investigate the effect of NRF2 on DCM. Results: CAV1 expression was significantly increased in the cardiac tissues of diabetic mice and HG-treated NRVMs. CAV1 deficiency significantly alleviated diabetes-induced myocardial hypertrophy, fibrosis, abnormal mitochondria, excessive reactive oxygen species production, and ferroptosis. Conversely, cardiac-specific overexpression of CAV1 exacerbated cardiac dysfunction and myocardial histological abnormalities caused by diabetes. Mechanistically, CAV1 directly bound to NRF2 and inhibited its nuclear translocation, reducing the transcription of glutamate cysteine ligase catalytic subunit (GCLC), accumulating excess peroxide, and inducing ferroptosis and myocardial injury. Conclusion: CAV1 exacerbates the progression of DCM by suppressing the NRF2/GCLC pathway, suggesting that targeting CAV1 is a potential therapeutic approach for DCM.

Caveolin-1-mediated LDL transcytosis across endothelial cells in atherosclerosis

Atherosclerosis is widely recognized as a chronic inflammatory disease of the arterial wall characterized by the progressive accumulation of lipids, inflammatory cells, and fibrous material in the subendothelial space of large arteries. The occurrence and pathogenesis of atherosclerosis are intricately linked to the deposition of low-density lipoprotein (LDL) in the arterial wall. LDL must cross the intact endothelium to reach the subendothelial space, with caveolin-1 assuming a crucial role in this process. Caveolin-1 is a 21-24 kDa membrane protein located in caveolae and highly expressed in endothelial cells. Previous investigations have demonstrated the pivotal role of caveolin-1 in fostering atherosclerosis through its modulation of membrane trafficking, cholesterol metabolism, and cellular signaling. However, how caveolin-1 regulates LDL transcytosis across endothelial cells in atherosclerosis remains unclear. We provide a comprehensive overview of recent research on the interplay between caveolin-1 and atherosclerosis, with a specific focus on elucidating the role of caveolin-1 in mediating LDL transcytosis across endothelial cells. This review furnishes theoretical foundations supporting the pivotal role of caveolin-1 in both the inception and progression of atherosclerosis. It underscores the prospective viability of caveolin-1 as a new therapeutic target for atherosclerosis and introduces novel perspectives for treatment strategies in the early stages of atherosclerosis.

Targeting NLRC5 in cardiomyocytes protects postinfarction cardiac injury by enhancing autophagy flux through the CAVIN1/CAV1 axis

NOD-like receptor (NLR) family proteins are implicated in various cardiovascular diseases. However, the precise role of NLRC5, the largest member of this family, in myocardial infarction (MI) remains poorly understood. This study reveals that NLRC5 is upregulated in the hearts of both patients with MI and MI mice. Silencing NLRC5 in cardiomyocytes impairs cardiac repair and functional recovery, while its overexpression enhances these processes. Furthermore, NLRC5 promotes autophagy in cardiomyocytes, and its protective effects are diminished upon autophagy inhibition. Mechanistically, NLRC5 interacts with CAVIN1, facilitating its degradation and subsequent downregulation of CAV1, which in turn increases the expression of the ATG12-ATG5 complex to stimulate autophagy. Conversely, CAV1 overexpression partially suppresses autophagy and attenuates the improvements in cardiac function observed in NLRC5-overexpressing MI hearts. This study highlights the critical regulatory role of NLRC5 in modulating cardiomyocyte autophagy flux, suggesting that NLRC5 activation may represent a promising therapeutic strategy for MI.

BMSCs-derived small extracellular vesicles antagonize cerebral endothelial Caveolin-1 driven autophagic degradation of tight-junction proteins to protect blood-brain barrier post-stroke

Bone marrow mesenchymal stem cells (BMSCs) -derived extracellular vesicles (EVs), especially small EVs (sEVs), were vastly reported to enable multiple restorative effects on ischemic stroke, yet the protective mechanism of blood-brain barrier (BBB) has not been fully illustrated. In the present study, we investigated the therapeutic effects and mechanism of BMSCs-derived sEVs on BBB injury after ischemic stroke. In-vivo, administering sEVs to transient middle cerebral artery occlusion (tMCAo) mice mitigated the brain infarct volume, BBB permeability and neural apoptosis, and improved the cerebral blood flow perfusion and neurological function. Simultaneously, cerebral vascular endothelial overexpressed Caveolin-1 (Cav-1) together with its strong co-localization with autophagosome protein LC3B were suppressed, and ZO-1 and Occludin expressions were enhanced, whose results were consistent with those of oxygen-glucose-deprivation/reperfusion (OGD/R)-insulted brain endothelial cells (BECs) in vitro. Furthermore, by employing Cav-1 siRNA and pcDNA3.1 transfection, Co-immunoprecipitation, cycloheximide assay, and molecular docking, it proved that brain endothelial Cav-1 was an essential upstream of autophagy activation, contributing to tight-junction proteins delegation via the autophagy-lysosomal pathway. Altogether, our study demonstrates the novel mechanism of Cav-1-dependent tight-junction proteins autophagic disruption on BBB integrity after ischemic stroke, and BMSC-sEVs treatment can reverse such hazard cascades.

The two major splice variants of scavenger receptor BI differ by their interactions with lipoproteins and cellular localization in endothelial cells

The scavenger receptor BI (SR-BI) facilitates the transport of both HDL and LDL through endothelial cells. Its two splice variants, SR-BIvar1 and SR-BIvar2, differ in their carboxy terminal domains. Only SR-BIvar1 contains the putative binding sites for the adapter proteins PDZ domain containing protein 1 (PDZK1) and dedicator of cytokinesis 4 (DOCK4), which limit the cell surface abundance and internalization of the receptor. To investigate the cellular localization of the SR-BI variants and their interaction with lipoproteins in endothelial cells, EA.hy926 cells were stably transfected with vectors encoding untagged, GFP- or mCherry-tagged constructs of the two SR-BI variants. Additionally, the cells were transfected with shRNAs against PDZK1 or DOCK4. Microscopy investigation showed that SR-BIvar1 was predominantly localized on the cell surface together with clathrin whereas SR-BIvar2 was absent from the cell surface but retrieved in endosomes and lysosomes. Accordingly, only SR-BIvar1 increased lipoprotein binding to endothelial while HDL and LDL uptake were enhanced by both variants. Silencing of PDZK1 or DOCK4 only reduced HDL association in SR-BIvar2 overexpressing cells while LDL association was reduced both in WT and SR-BIvar2 overexpressing cells. In conclusion, either SR-BI variant facilitates the uptake of HDL and LDL into endothelial cells, however by different mechanisms and trafficking routes. This dual role may explain why the loss of DOCK4 or PDZK1 differently affects the uptake of HDL and LDL in different endothelial cells.

mTORC1 Signaling in Brain Endothelial Progenitors Contributes to CCM Pathogenesis

BACKGROUND

Cerebral vascular malformations (CCMs) are primarily found within the brain, where they result in increased risk for stroke, seizures, and focal neurological deficits. The unique feature of the brain vasculature is the blood-brain barrier formed by the brain neurovascular unit. Recent studies suggest that loss of CCM genes causes disruptions of blood-brain barrier integrity as the inciting events for CCM development. CCM lesions are proposed to be initially derived from a single clonal expansion of a subset of angiogenic venous capillary endothelial cells (ECs) and respective resident endothelial progenitor cells (EPCs). However, the critical signaling events in the subclass of brain ECs/EPCs for CCM lesion initiation and progression are unclear.

METHODS

Brain EC-specific CCM3-deficient (Pdcd10BECKO) mice were generated by crossing Pdcd10fl/fl mice with Mfsd2a-CreERT2 mice. Single-cell RNA-sequencing analyses were performed by the chromium single-cell platform (10× genomics). Cell clusters were annotated into EC subtypes based on visual inspection and GO analyses. Cerebral vessels were visualized by 2-photon in vivo imaging and tissue immunofluorescence analyses. Regulation of mTOR (mechanistic target of rapamycin) signaling by CCM3 and Cav1 (caveolin-1) was performed by cell biology and biochemical approaches.

RESULTS

Single-cell RNA-sequencing analyses from P10 Pdcd10BECKO mice harboring visible CCM lesions identified upregulated CCM lesion signature and mitotic EC clusters but decreased blood-brain barrier-associated EC clusters. However, a unique EPC cluster with high expression levels of stem cell markers enriched with mTOR signaling was identified from early stages of the P6 Pdcd10BECKO brain. Indeed, mTOR signaling was upregulated in both mouse and human CCM lesions. Genetic deficiency of Raptor (regulatory-associated protein of mTOR), but not of Rictor (rapamycin-insensitive companion of mTOR), prevented CCM lesion formation in the Pdcd10BECKO model. Importantly, the mTORC1 (mTOR complex 1) pharmacological inhibitor rapamycin suppressed EPC proliferation and ameliorated CCM pathogenesis in Pdcd10BECKO mice. Mechanistic studies suggested that Cav1/caveolae increased in CCM3-depleted EPC-mediated intracellular trafficking and complex formation of the mTORC1 signaling proteins.

CONCLUSIONS

CCM3 is critical for maintaining blood-brain barrier integrity and CCM3 loss-induced mTORC1 signaling in brain EPCs initiates and facilitates CCM pathogenesis.

Biomechanics-mediated endocytosis in atherosclerosis

Biomechanical forces, including vascular shear stress, cyclic stretching, and extracellular matrix stiffness, which influence mechanosensitive channels in the plasma membrane, determine cell function in atherosclerosis. Being highly associated with the formation of atherosclerotic plaques, endocytosis is the key point in molecule and macromolecule trafficking, which plays an important role in lipid transportation. The process of endocytosis relies on the mobility and tension of the plasma membrane, which is sensitive to biomechanical forces. Several studies have advanced the signal transduction between endocytosis and biomechanics to elaborate the developmental role of atherosclerosis. Meanwhile, increased plaque growth also results in changes in the structure, composition and morphology of the coronary artery that contribute to the alteration of arterial biomechanics. These cross-links of biomechanics and endocytosis in atherosclerotic plaques play an important role in cell function, such as cell phenotype switching, foam cell formation, and lipoprotein transportation. We propose that biomechanical force activates the endocytosis of vascular cells and plays an important role in the development of atherosclerosis.

CircBIRC6 facilitates the malignant progression via miR-488/GRIN2D-mediated CAV1-autophagy signal axis in gastric cancer

Circular RNAs (circRNAs) represent a novel class of non-coding RNAs that play significant roles in tumorigenesis and tumor progression. High-throughput sequencing of gastric cancer (GC) tissues has identified circRNA BIRC6 (circBIRC6) as a potential circRNA derived from the BIRC6 gene, exhibiting significant upregulation in GC tissues. The expression of circBIRC6 is notably elevated in GC patients. Functionally, it acts as a molecular sponge for miR-488, consequently upregulating GRIN2D expression and promoting GC proliferation, migration, and invasion. Moreover, overexpression of circBIRC6 leads to increased GRIN2D expression, which in turn enhances caveolin-1 (CAV1) expression, resulting in autophagy deficiency due to miR-488 sequestration. This cascade of events significantly influences tumorigenesis in vivo. Our findings collectively illustrate that the CircBIRC6-miR-488-GRIN2D axis fosters CAV1 expression in GC cells, thereby reducing autophagy levels. Both circBIRC6 and GRIN2D emerge as potential targets for treatment and independent prognostic factors for GC patients.

The long coiled-coil protein NECC2 regulates oxLDL-induced endothelial oxidative damage and exacerbates atherosclerosis development in apolipoprotein E -/- mice

Oxidized low density lipoprotein (oxLDL)-induced endothelial oxidative damage promotes the development of atherosclerosis. Caveolae play an essential role in maintaining the survival and function of vascular endothelial cell (VEC). It is reported that the long coiled-coil protein NECC2 is localized in caveolae and is associated with neural cell differentiation and adipocyte formation, but its role in VECs needs to be clarified. Our results showed NECC2 expression increased in the endothelium of plaque-loaded aortas and oxLDL-treated HUVECs. Down-regulation of NECC2 by NECC2 siRNA or compound YF-307 significantly inhibited oxLDL-induced VEC apoptosis and the adhesion factors expression. Remarkably, inhibition of NECC2 expression in the endothelium of apoE-/- mice by adeno-associated virus (AAV)-carrying NECC2 shRNA or compound YF-307 alleviated endothelium injury and restricted atherosclerosis development. The immunoprecipitation results confirmed that NECC2 interacted with Tyk2 and caveolin-1(Cav-1) in VECs, and NECC2 further promoted the phosphorylation of Cav-1 at Tyr14 b y activating Tyk2 phosphorylation. On the other hand, inhibiting NECC2 levels suppressed oxLDL-induced phosphorylation of Cav-1, uptake of oxLDL by VECs, accumulation of intracellular reactive oxygen species and activation of NF-κB. Our findings suggest that NECC2 may contribute to oxLDL-induced VEC injury and atherosclerosis via modulating Cav-1 phosphorylation through Tyk2. This work provides a new concept and drug target for treating atherosclerosis.

Traditional Chinese medicine and its active substances reduce vascular injury in diabetes via regulating autophagic activity

Due to its high prevalence, poor prognosis, and heavy burden on healthcare costs, diabetic vascular complications have become a significant public health issue. Currently, the molecular and pathophysiological mechanisms underlying diabetes-induced vascular complications remain incompletely understood. Autophagy, a highly conserved process of lysosomal degradation, maintains intracellular homeostasis and energy balance via removing protein aggregates, damaged organelles, and exogenous pathogens. Increasing evidence suggests that dysregulated autophagy may contribute to vascular abnormalities in various types of blood vessels, including both microvessels and large vessels, under diabetic conditions. Traditional Chinese medicine (TCM) possesses the characteristics of "multiple components, multiple targets and multiple pathways," and its safety has been demonstrated, particularly with minimal toxicity in liver and kidney. Thus, TCM has gained increasing attention from researchers. Moreover, recent studies have indicated that Chinese herbal medicine and its active compounds can improve vascular damage in diabetes by regulating autophagy. Based on this background, this review summarizes the classification, occurrence process, and related molecular mechanisms of autophagy, with a focus on discussing the role of autophagy in diabetic vascular damage and the protective effects of TCM and its active compounds through the regulation of autophagy in diabetes. Moreover, we systematically elucidate the autophagic mechanisms by which TCM formulations, individual herbal extracts, and active compounds regulate diabetic vascular damage, thereby providing new candidate drugs for clinical treatment of vascular complications in diabetes. Therefore, further exploration of TCM and its active compounds with autophagy-regulating effects holds significant research value for achieving targeted therapeutic approaches for diabetic vascular complications.

N-acetylneuraminic acid modulates SQSTM1/p62 sialyation-mediated ubiquitination degradation contributing to vascular endothelium dysfunction in experimental atherosclerosis mice

Sialic acid (SIA) has been reported to be a risk factor for atherosclerosis (AS) due to its high plasma levels in such patients. However, the effect of increasing SIA in circulation on endothelial function during AS progression remains unclear. In the present study, ApoE-/- mice and endothelial cells line (HUVEC cells) were applied to investigate the effect of SIA on AS progression and its potential molecular mechanism. In vivo, mice were injected intraperitoneally with Neu5Ac (main form of SIA) to keep high-level SIA in circulation. ORO, H&E, and Masson staining were applied to detect the plaque progression. In vitro, HUVECs were treated with Neu5Ac at different times, CCK-8, RT-PCR, western blot, and immunoprecipitation methods were used to analyze its effects on endothelial function and the potential involved mechanism. Results from the present study showed that high plasma levels of Neu5Ac in ApoE-/- mice could aggravate the plaque areas as well as increase necrotic core areas and collagen fiber contents. Remarkably, Neu5Ac levels in circulation displayed a positive correlation with AS plaque areas. Furthermore, results from HUVECs showed that Neu5Ac inhibited cells viability in a time/dose-dependent manner, by then induced the activation of inflammation makers such as ICAM-1 and IL-1β. Mechanism study showed that the activation of excessive autophagy medicated by SQSTM1/p62 displayed an important role in endothelium inflammatory injury. Neu5Ac could modify SQSTM1/p62 as a sialylation protein, and then increase its level with ubiquitin binding, further inducing ubiquitination degradation and being involved in the excessive autophagy pathway. Inhibition of sialylation by P-3Fax-Neu5Ac, a sialyltransferase inhibitor, reduced the binding of SQSTM1/p62 to ubiquitin. Together, these findings indicated that Neu5Ac increased SQSTM1/p62-ubiquitin binding through sialylation modification, thereby inducing excessive autophagy and subsequent endothelial injury. Inhibition of SQSTM1/p62 sialylation might be a potential strategy for preventing such disease with high levels of Neu5Ac in circulation.

Cell death in atherosclerosis

A complex and evolutionary process that involves the buildup of lipids in the arterial wall and the invasion of inflammatory cells results in atherosclerosis. Cell death is a fundamental biological process that is essential to the growth and dynamic equilibrium of all living things. Serious cell damage can cause a number of metabolic processes to stop, cell structure to be destroyed, or other irreversible changes that result in cell death. It is important to note that studies have shown that the two types of programmed cell death, apoptosis and autophagy, influence the onset and progression of atherosclerosis by controlling these cells. This could serve as a foundation for the creation of fresh atherosclerosis prevention and treatment strategies. Therefore, in this review, we summarized the molecular mechanisms of cell death, including apoptosis, pyroptosis, autophagy, necroptosis, ferroptosis and necrosis, and discussed their effects on endothelial cells, vascular smooth muscle cells and macrophages in the process of atherosclerosis, so as to provide reference for the next step to reveal the mechanism of atherosclerosis.

Chinese herb couple against diabetes: integrating network pharmacology and mechanism study

Cassia twig is a dry twig of Cinnamomum cassia Presl, a Lauraceae plant. Astragalus L is one of the largest genuses of flowering plants in the Leguminosae family. Roots of A. membranaceus Bge. var. mongholicus (Bge.) Hsiao, A. membranaceus (Fisch.) Bge. Chinese herb couple refers to the matching of two herbs in pairs, mostly with synergistic effects or toxicity reduction. This Chinese herb couple (Cassia twig-Astragalus) come from the classic famous book "Zhang Xichun's book on Chinese herb couple", which is widely used to treat diabetes. Moreover, both Cassia twig and Astragalus belong to the homology of medicine and food. However, its mechanism is still unclear. The study identified the effective components of Cassia twig-Astragalus by UPLC-Q-TOF-MS/MS and investigated the mechanism of Cassia twig-Astragalus in treating diabetes by virtue of network pharmacology, molecular docking and experimental verification. Firstly, based on UPLC-Q-TOF-MS/MS and network pharmacology, a total of 10 active ingredients of Astragalus and 6 active ingredients of Cassia twig were screened, and a total of 13 key targets were obtained. There were 64 targets at the intersection of Cassia twig-Astragalus with diabetes, mainly including IL-17, TNF, NF-κβ, AGE-RAGE signaling pathway, etc. It mainly involves the response of cells to insulin stimulation, the response to insulin and the positive regulation of cell adhesion. Secondly, molecular docking results showed that quercetin has good binding activities with AKT1 and TNF. Calycosin has good binding activities with AKT1, TNF and CAV1. Formononetin has good binding activities with TNF and IL-6. Isorhamnetin has good binding activities with AKT1, TNF and IL-6. Finally, the animal experiments showed that Cassia twig-Astragalus could improve the body weight, blood glucose and glucose tolerance in diabetic rats. After the intervention with Cassia twig-Astragalus, the inflammatory factors (IL-10, TNF-α, IL-6) were significantly improved in diabetic rats, which also effectively reduced TG and TC.

Identification of Structures Labeled by Indocyanine Green in the Rat Choroid and Retina Can Guide Interpretation of Indocyanine Green Angiography

Purpose

Indocyanine green (ICG) is an albumin and lipoprotein binding dye absorbing in the far red used in angiography to visualize choroidal vessels (ICG angiography [ICGA]). To guide interpretation, ICG transport in the choroid, RPE, and retina of rats was studied.

Methods

Two conditions were used: RPE/choroid organoculture, incubated for 45 minutes in DMEM medium, 1% fetal bovine serum containing 0.25 mg/mL ICG and RPE/choroid and neural retina flat-mounts at 1 and 6 hours after intravenous ICG injection. Early and late sequences of ICGA were recorded until 6 hours. Ultra-deep red confocal microscope was used to localize ICG in flat-mounts and immunohistochemistry was performed for caveolin-1, tryptase (mast cell marker), and tubulin β3 (a nerve marker).

Results

In the organoculture, ICG penetrated homogeneously in the cytoplasm and stained the membranes of the RPE. At 1 hour after intravenous injection, ICG appeared in fine granules in RPE, partly labeled with caveolin-1 and decreasing at 6 hours. At 1 hour and 6 hours, ICG was found in the retinal vessels, faintly in the inner retina, and in the photoreceptor outer segments at 6 hours. In the choroid, ICG colocalized with mast cells, immunostained with tryptase, and accumulated along the large tubulin β3-labeled nerve bundles. The hypothesis was raised on the interpretation of late ICGA infrared photography in case of transthyretin amyloidosis with neuropathy.

Conclusions

Beside being a vascular dye, ICG is transported from the vessels to the RPE toward the outer retina. It stains mast cells and large choroidal nerves. These observations could help the analysis of ICGA images.

Clinical value of echocardiography combined with serum Cav-1, NFATc1, and PAI-1 in the diagnosis of Kawasaki disease complicated with coronary artery lesions

To analyze the clinical value of echocardiography combined with serum lacuna protein-1 (Cav-1), activated T cell nuclear factor C1 (NFATc1), and plasminogen activator inhibitor-1 (PAI-1) in the diagnosis of Kawasaki disease (KD) complicated with coronary artery lesions (CAL). A total of 200 children with KD treated in our hospital from January 2019 to October 2021 were grouped as the KD alone group (n = 56) and the KD complicated with CAL group (n = 144) according to the results of coronary angiography. The levels of Cav-1, NFATc1, and PAI-1 were detected by enzyme-linked immunosorbent assay. Echocardiography was performed and the internal diameters of left and right coronary arteries were compared between the two groups. The area under the curve (AUC), sensitivity, and specificity of echocardiography combined with serum Cav-1, NFATc1, and PAI-1 in the diagnosis of KD complicated with CAL were analyzed with receiver operating characteristic (ROC) curve. Coronary angiography, as the gold standard, showed that the sensitivity of echocardiography in diagnosing KD with CAL was 88.19% (127/144), the specificity was 66.07% (37/56), and the accuracy was 82.00% (164/200). ROC curve analysis revealed that the AUC of KD complicated with CAL diagnosed by echocardiography, Cav-1, NFATc1, and PAI-1 was 0.819, 0.715, 0.688, and 0.663, respectively, and the AUC of combined diagnosis of the four was 0.896. The combination of echocardiography, Cav-1, NFATc1, and PAI-1 has high value in diagnosing KD complicated with CAL, which can be widely used in clinical practice.

Caveolin-1 is critical for hepatic iron storage capacity in the development of nonalcoholic fatty liver disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is associated with disordered lipid and iron metabolism. Our previous study has substantiated the pivotal role of Caveolin-1 (Cav-1) in protecting hepatocytes and mediating iron metabolism in the liver. This study aimed to explore the specific mechanisms underlying the regulation of iron metabolism by Cav-1 in NAFLD.

METHODS

Hepatocyte-specific Cav-1 overexpression mice and knockout mice were used in this study. Cav-1-knockdown of RAW264.7 cells and mouse primary hepatocytes were performed to verify the changes in vitro. Moreover, a high-fat diet and palmitic acid plus oleic acid treatment were utilized to construct a NAFLD model in vivo and in vitro, respectively, while a high-iron diet was used to construct an in vivo iron overload model. Besides, iron concentration, the expression of Cav-1 and iron metabolism-related proteins in liver tissue or serum were detected using iron assay kit, Prussian blue staining, Western blotting, immunofluorescence staining, immunohistochemical staining and ELISA. The related indicators of lipid metabolism and oxidative stress were evaluated by the corresponding reagent kit and staining.

RESULTS

Significant disorder of lipid and iron metabolism occurred in NAFLD. The expression of Cav-1 was decreased in NAFLD hepatocytes (P < 0.05), accompanied by iron metabolism disorder. Cav-1 enhanced the iron storage capacity of hepatocytes by activating the ferritin light chain/ferritin heavy chain pathway in NAFLD, subsequently alleviating the oxidative stress induced by excess ferrous ions in the liver. Further, CD68+CD163+ macrophages expressing Cav-1 were found to accelerate iron accumulation in the liver, which was contrary to the effect of Cav-1 in hepatocytes. Positive correlations were also observed between the serum Cav-1 concentration and the serum iron-related protein levels in NAFLD patients and healthy volunteers (P < 0.05).

CONCLUSIONS

These findings confirm that Cav-1 is an essential target protein that regulates iron and lipid metabolic homeostasis. It is a pivotal molecule for predicting and protecting against the development of NAFLD.

Caveolin-1: A Review of Intracellular Functions, Tissue-Specific Roles, and Epithelial Tight Junction Regulation

Caveolin-1 (Cav1) is a vital protein for many cellular processes and is involved in both the positive and negative regulation of these processes. Cav1 exists in multiple cellular compartments depending on its role. Of particular interest is its contribution to the formation of plasma membrane invaginations called caveolae and its involvement in cytoskeletal interactions, endocytosis, and cholesterol trafficking. Cav1 participates in stem cell differentiation as well as proliferation and cell death pathways, which is implicated in tumor growth and metastasis. Additionally, Cav1 has tissue-specific functions that are adapted to the requirements of the cells within those tissues. Its role has been described in adipose, lung, pancreatic, and vascular tissue and in epithelial barrier maintenance. In both the intestinal and the blood brain barriers, Cav1 has significant interactions with junctional complexes that manage barrier integrity. Tight junctions have a close relationship with Cav1 and this relationship affects both their level of expression and their location within the cell. The ubiquitous nature of Cav1 both within the cell and within specific tissues is what makes the protein important for ongoing research as it can assist in further understanding pathophysiologic processes and can potentially be a target for therapies.

Receptor-interacting protein kinase 2 (RIPK2) profoundly contributes to post-stroke neuroinflammation and behavioral deficits with microglia as unique perpetrators

BACKGROUND

Receptor-interacting protein kinase 2 (RIPK2) is a serine/threonine kinase whose activity propagates inflammatory signaling through its association with pattern recognition receptors (PRRs) and subsequent TAK1, NF-κB, and MAPK pathway activation. After stroke, dead and dying cells release a host of damage-associated molecular patterns (DAMPs) that activate PRRs and initiate a robust inflammatory response. We hypothesize that RIPK2 plays a damaging role in the progression of stroke injury by enhancing the neuroinflammatory response to stroke and that global genetic deletion or microglia-specific conditional deletion of Ripk2 will be protective following ischemic stroke.

METHODS

Adult (3-6 months) male mice were subjected to 45 min of transient middle cerebral artery occlusion (tMCAO) followed by 24 h, 48 h, or 28 days of reperfusion. Aged male and female mice (18-24 months) were subjected to permanent ischemic stroke and sacrificed 48 h later. Infarct volumes were calculated using TTC staining (24-48 h) or Cresyl violet staining (28d). Sensorimotor tests (weight grip, vertical grid, and open field) were performed at indicated timepoints. Blood-brain barrier (BBB) damage, tight junction proteins, matrix metalloproteinase-9 (MMP-9), and neuroinflammatory markers were assessed via immunoblotting, ELISA, immunohistochemistry, and RT-qPCR. Differential gene expression profiles were generated through bulk RNA sequencing and nanoString®.

RESULTS

Global genetic deletion of Ripk2 resulted in decreased infarct sizes and reduced neuroinflammatory markers 24 h after stroke compared to wild-type controls. Ripk2 global deletion also improved both acute and long-term behavioral outcomes with powerful effects on reducing infarct volume and mortality at 28d post-stroke. Conditional deletion of microglial Ripk2 (mKO) partially recapitulated our results in global Ripk2 deficient mice, showing reductive effects on infarct volume and improved behavioral outcomes within 48 h of injury. Finally, bulk transcriptomic profiling and nanoString data demonstrated that Ripk2 deficiency in microglia decreases genes associated with MAPK and NF-κB signaling, dampening the neuroinflammatory response after stroke injury by reducing immune cell activation and peripheral immune cell invasion.

CONCLUSIONS

These results reveal a hitherto unknown role for RIPK2 in the pathogenesis of ischemic stroke injury, with microglia playing a distinct role. This study identifies RIPK2 as a potent propagator of neuroinflammatory signaling, highlighting its potential as a therapeutic target for post-stroke intervention.

Transcranial Photosensitizer-Free Laser Treatment of Glioblastoma in Rat Brain

Over sixty years, laser technologies have undergone a technological revolution and become one of the main tools in biomedicine, particularly in neuroscience, neurodegenerative diseases and brain tumors. Glioblastoma is the most lethal form of brain cancer, with very limited treatment options and a poor prognosis. In this study on rats, we demonstrate that glioblastoma (GBM) growth can be suppressed by photosensitizer-free laser treatment (PS-free-LT) using a quantum-dot-based 1267 nm laser diode. This wavelength, highly absorbed by oxygen, is capable of turning triplet oxygen to singlet form. Applying 1267 nm laser irradiation for a 4 week course with a total dose of 12.7 kJ/cm2 firmly suppresses GBM growth and increases survival rate from 34% to 64%, presumably via LT-activated apoptosis, inhibition of the proliferation of tumor cells, a reduction in intracranial pressure and stimulation of the lymphatic drainage and clearing functions. PS-free-LT is a promising breakthrough technology in non- or minimally invasive therapy for superficial GBMs in infants as well as in adult patients with high photosensitivity or an allergic reaction to PSs.

Caveolin-1 in endothelial cells: A potential therapeutic target for atherosclerosis

Atherosclerosis (AS) is a chronic vascular disease characterized by lipid accumulation and the activation of the inflammatory response; it remains the leading nation-wide cause of death. Early in the progression of AS, stimulation by pro-inflammatory agonists (TNF-α, LPS, and others), oxidized lipoproteins (ox-LDL), and biomechanical stimuli (low shear stress) lead to endothelial cell activation and dysfunction. Consequently, it is crucial to investigate how endothelial cells respond to different stressors and ways to alter endothelial cell activation in AS development, as they are the earliest cells to respond. Caveolin-1 (Cav1) is a 21-24-kDa membrane protein located in caveolae and highly expressed in endothelial cells, which plays a vital role in regulating lipid transport, inflammatory responses, and various cellular signaling pathways and has atherogenic effects. This review summarizes recent studies on the structure and physiological functions of Cav1 and outlines the potential mechanisms it mediates in AS development. Included are the roles of Cav1 in the regulation of endothelial cell autophagy, response to shear stress, modulation of the eNOS/NO axis, and transduction of inflammatory signaling pathways. This review provides a rationale for proposing Cav1 as a novel target for the prevention of AS, as well as new ideas for therapeutic strategies for early AS.

Proteostasis and resilience in the mechanically-stressed vascular endothelium

Endothelial homeostasis is a central feature of vascular health. The vascular endothelium is under constant mechanical stress resulting from blood flow and, therefore, requires a high degree of resilience to adapt to stresses and resist development of disease. In this review, we discuss the molecular mechanisms by which the endothelium maintains proteostasis in response to haemodynamic forces by regulating three key areas: protein synthesis, recycling and degradation.

METTL3 promotes hyperoxia-induced pyroptosis in neonatal bronchopulmonary dysplasia by inhibiting ATG8-mediated autophagy

OBJECTIVES

N6-Methyladenosine (m6A) modification plays a vital role in lung disorders. However, the potential of m6A in neonatal Bronchopulmonary Dysplasia (BPD) has not been reported. This study aimed to investigate the roles of METTL3 in BPD.

METHODS

BPD models were established by hyperoxia in vivo and in vitro. Histological analysis was determined using HE staining. Gene expression was determined using Western blotting, qRT-PCR, and immunofluorescence. The release of IL-1β and IL-18 was detected using ELISA. The m6A sites of ATG8 were predicted by SCRAPM and verified by MeRIP assay. The location of GSDMD and ATG8 was determined by FISH assay. The interaction between ATG8 and GSDMD was detected using Coimmunoprecipitation (Co-IP). Cell pyroptosis was determined using flow cytometry and TUNEL assays.

RESULTS

METTL3 was overexpressed in BPD, which was accompanied by an increase in m6A levels. Interestingly, METTL3 suppressed hyperoxia-mediated damage and pyroptosis in BEAS-2B cells and promoted cell autophagy. METTL3-mediated m6A modification of ATG8 suppressed its expression and disrupted the interaction between ATG8 and GSDMD. However, autophagy inhibition induced pyroptosis in BEAS-2B cells. In vivo assays showed that METTL3-mediated autophagy inhibition induced a decrease in the radial alveolar count and an increase in the mean linear intercept and promoted cell pyroptosis.

CONCLUSION

In conclusion, METTL3-mediated cell pyroptosis promotes BPD by regulating the m6A modification of ATG8. This may provide new insight into the development of BPD.

Physiological and pathological characteristics of vascular endothelial injury in diabetes and the regulatory mechanism of autophagy

Vascular endothelial injury in diabetes mellitus (DM) is the major cause of vascular disease, which is closely related to the occurrence and development of a series of vascular complications and has a serious negative impact on a patient's health and quality of life. The primary function of normal vascular endothelium is to function as a barrier function. However, in the presence of DM, glucose and lipid metabolism disorders, insulin resistance, inflammatory reactions, oxidative stress, and other factors cause vascular endothelial injury, leading to vascular endothelial lesions from morphology to function. Recently, numerous studies have found that autophagy plays a vital role in regulating the progression of vascular endothelial injury. Therefore, this article compares the morphology and function of normal and diabetic vascular endothelium and focuses on the current regulatory mechanisms and the important role of autophagy in diabetic vascular endothelial injury caused by different signal pathways. We aim to provide some references for future research on the mechanism of vascular endothelial injury in DM, investigate autophagy's protective or injurious effect, and study potential drugs using autophagy as a target.

Mechanisms of endothelial flow sensing

Fluid shear stress plays a key role in sculpting blood vessels during development, in adult vascular homeostasis and in vascular pathologies. During evolution, endothelial cells evolved several mechanosensors that convert physical forces into biochemical signals, a process termed mechanotransduction. This Review discusses our understanding of endothelial flow sensing and suggests important questions for future investigation.

The redox activity of polychlorinated biphenyl quinone metabolite orchestrates its pro-atherosclerosis effect via CAV1 phosphorylation

Further investigations are required to prove that polychlorinated biphenyls (PCBs) exposure is a cardiovascular disease risk factor. Unlike previous studies that attributed the atherogenic effect of PCBs to aryl hydrocarbon receptor activation, we illustrated a new mechanism involved in the redox reactivity of PCBs. We discover the redox reactivity of quinone moiety is the primary factor for PCB29-pQ-induced proinflammatory response, which highly depends on the status of caveolin 1 (CAV1) phosphorylation. PCB29-pQ-mediated CAV1 phosphorylation disrupts endothelial nitric oxide synthase, toll-like receptor 4, and reduces interleukin-1 receptor-associated kinase 1 binding with CAV1. Phosphorylated proteomics analysis indicated that PCB29-pQ treatment significantly enriched phosphorylated peptides in protein binding functions, inflammation, and apoptosis signaling. Meanwhile, apolipoprotein E knockout (ApoE^-/-) mice exposed to PCB29-pQ had increased atherosclerotic plaques compared to the vehicle group, while this effect was significantly reduced in ApoE^-/-/CAV1^-/- double knockout mice. Thus, we hypothesis CAV1 is a platform for proinflammatory cascades induced by PCB29-pQ on atherosclerotic processes. Together, these findings confirm that the redox activity of PCB metabolite plays a role in the etiology of atherosclerosis.

Caveolin-1 and Atherosclerosis: Regulation of LDLs Fate in Endothelial Cells

Caveolae are 50-100 nm cell surface plasma membrane invaginations observed in terminally differentiated cells. They are characterized by the presence of the protein marker caveolin-1. Caveolae and caveolin-1 are involved in regulating several signal transduction pathways and processes. It is well recognized that they have a central role as regulators of atherosclerosis. Caveolin-1 and caveolae are present in most of the cells involved in the development of atherosclerosis, including endothelial cells, macrophages, and smooth muscle cells, with evidence of either pro- or anti-atherogenic functions depending on the cell type examined. Here, we focused on the role of caveolin-1 in the regulation of the LDLs' fate in endothelial cells.

Yue-bi-tang attenuates adriamycin-induced nephropathy edema through decreasing renal microvascular permeability via inhibition of the Cav-1/ eNOS pathway

Edema is one of the most typical symptoms of nephrotic syndrome. Increased vascular permeability makes a significant contribution to the progression of edema. Yue-bi-tang (YBT) is a traditional formula with excellent clinical efficacy in the treatment of edema. This study investigated the effect of YBT on renal microvascular hyperpermeability-induced edema in nephrotic syndrome and its mechanism. In our study, the content of target chemical components of YBT was identified using UHPLC-Q-Orbitrap HRMS analysis. A nephrotic syndrome model was replicated based on male Sprague-Dawley rats with Adriamycin (6.5 mg/kg) by tail vein injection. The rats were randomly divided into control, model, prednisone, and YBT (22.2 g/kg, 11.1 g/kg, and 6.6 g/kg) groups. After 14 d of treatment, the severity of renal microvascular permeability, edema, the degree of renal injury, and changes in the Cav-1/eNOS pathway were assessed. We found that YBT could regulate renal microvascular permeability, alleviate edema, and reduce renal function impairment. In the model group, the protein expression of Cav-1 was upregulated, whereas VE-cadherin was downregulated, accompanied by the suppression of p-eNOS expression and activation of the PI3K pathway. Meanwhile, an increased NO level in both serum and kidney tissues was observed, and the above situations were improved with YBT intervention. It thus indicates YBT exerts therapeutic effects on the edema of nephrotic syndrome, as it improves the hyperpermeability of renal microvasculature, and that YBT is engaged in the regulation of Cav-1/eNOS pathway-mediated endothelial function.

Baicalin inhibits influenza A (H1N1)-induced pyroptosis of lung alveolar epithelial cells via caspase-3/GSDME pathway

Baicalin (7-d-glucuronic acid-5, 6-dihydroxyflavone) derived from the root of Scutellaria baicalensis used as Traditional Chinese Medicine (TCM) has been revealed to exert potential antiviral activity via various pathways, while the molecular mechanisms have not been fully understood. Pyroptosis, an inflammatory form of programmed cell death (PCD), is reported to play a crucial role in host cell fate during viral infection. In this study, transcriptome analysis of mice lung tissue reveals that baicalin reverses the alterations of the mRNA levels of PCD-associated genes upon H1N1 challenge, with a concomitant decrease in the population of H1N1-induced propidium iodide (PI)⁺ and Annexin Ⅴ⁺ cells. Intriguingly, we find that baicalin contributes to the survival of infected lung alveolar epithelial cells partly through its inhibition of H1N1-induced cell pyroptosis, which is manifested by reduced bubble-like protrusion cells and lactate dehydrogenase (LDH) release. Moreover, the antipyroptosis effect of baicalin in response to H1N1 infection is found to be mediated by its repression on caspase-3/Gasdermin E (GSDME) pathway. Cleaved caspase-3 and N-terminal fragment of GSDME (GSDME-N) are detected in H1N1-infected cell lines and mice lung tissues, which are markedly reversed by baicalin treatment. Furthermore, inhibition of caspase-3/GSDME pathway by caspase-3 inhibitor or siRNA exerts an antipyroptosis effect equal to that of baicalin treatment in infected A549 and BEAS-2B cells, indicating a pivotal role of caspase-3 in the antiviral activities of baicalin. Conclusively, for the first time, we demonstrate that baicalin could effectively suppress H1N1-induced pyroptosis of lung alveolar epithelial cells via caspase-3/GSDME pathway both in vitro and in vivo.

Integrated single-cell RNA-seq analysis reveals the vital cell types and dynamic development signature of atherosclerosis

Introduction: In the development of atherosclerosis, the remodeling of blood vessels is a key process involving plaque formation and rupture. So far, most reports mainly believe that macrophages, smooth muscle cells, and endothelial cells located at the intima and media of artery play the key role in this process. Few studies had focused on whether fibroblasts located at adventitia are involved in regulating disease process.

Methods and results: In this study, we conducted in-depth analysis of single-cell RNA-seq data of the total of 18 samples from healthy and atherosclerotic arteries. This study combines several analysis methods including transcription regulator network, cell-cell communication network, pseudotime trajectory, gene set enrichment analysis, and differential expression analysis. We found that SERPINF1 is highly expressed in fibroblasts and is involved in the regulation of various signaling pathways.

Conclusion: Our research reveals a potential mechanism of atherosclerosis, SERPINF1 regulates the formation and rupture of plaques through the Jak-STAT signaling pathway, which may provide new insights into the pathological study of disease. Moreover, we suggest that SRGN and IGKC as potential biomarkers for unstable arterial plaques.

Long-term administration of Western diet induced metabolic syndrome in mice and causes cardiac microvascular dysfunction, cardiomyocyte mitochondrial damage, and cardiac remodeling involving caveolae and caveolin-1 expression

BACKGROUND

Long-term consumption of an excessive fat and sucrose diet (Western diet, WD) has been considered a risk factor for metabolic syndrome (MS) and cardiovascular disease. Caveolae and caveolin-1 (CAV-1) proteins are involved in lipid transport and metabolism. However, studies investigating CAV-1 expression, cardiac remodeling, and dysfunction caused by MS, are limited. This study aimed to investigate the correlation between the expression of CAV-1 and abnormal lipid accumulation in the endothelium and myocardium in WD-induced MS, and the occurrence of myocardial microvascular endothelial cell dysfunction, myocardial mitochondrial remodeling, and damage effects on cardiac remodeling and cardiac function.

METHODS

We employed a long-term (7 months) WD feeding mouse model to measure the effect of MS on caveolae/vesiculo-vacuolar organelle (VVO) formation, lipid deposition, and endothelial cell dysfunction in cardiac microvascular using a transmission electron microscopy (TEM) assay. CAV-1 and endothelial nitric oxide synthase (eNOS) expression and interaction were evaluated using real-time polymerase chain reaction, Western blot, and immunostaining. Cardiac mitochondrial shape transition and damage, mitochondria-associated endoplasmic reticulum membrane (MAM) disruption, cardiac function change, caspase-mediated apoptosis pathway activation, and cardiac remodeling were examined using TEM, echocardiography, immunohistochemistry, and Western blot assay.

RESULTS

Our study demonstrated that long-term WD feeding caused obesity and MS in mice. In mice, MS increased caveolae and VVO formation in the microvascular system and enhanced CAV-1 and lipid droplet binding affinity. In addition, MS caused a significant decrease in eNOS expression, vascular endothelial cadherin, and β-catenin interactions in cardiac microvascular endothelial cells, accompanied by impaired vascular integrity. MS-induced endothelial dysfunction caused massive lipid accumulation in the cardiomyocytes, leading to MAM disruption, mitochondrial shape transition, and damage. MS promoted brain natriuretic peptide expression and activated the caspase-dependent apoptosis pathway, leading to cardiac dysfunction in mice.

CONCLUSION

MS resulted in cardiac dysfunction, remodeling by regulating caveolae and CAV-1 expression, and endothelial dysfunction. Lipid accumulation and lipotoxicity caused MAM disruption and mitochondrial remodeling in cardiomyocytes, leading to cardiomyocyte apoptosis and cardiac dysfunction and remodeling.

Klotho ameliorates angiotension-II-induced endothelial senescence via restoration of autophagy by inhibiting Wnt3a/GSK-3β/mTOR signaling: A potential mechanism involved in prognostic performance of Klotho in coronary atherosclerotic disease

OBJECTIVE

We aimed to evaluate the prognostic performance of circulating Klotho in coronary atherosclerotic disease (CAD), and to further explore the effect of Klotho on stress-mediated endothelial senescence and underlying mechanism.

METHODS

A cohort of 295 patients had a 12-month follow-up for major adverse cardiovascular events (MACE). Serum Klotho was detected by enzyme linked immunosorbent assay. Cell viability, SA-β-Gal staining, the expression of P53 and P16 were analyzed for endothelial senescence. Oxidative stress was evaluated by measurement of reactive oxygen species, superoxide dismutase and malondialdehyde. LC3, P62, Wnt3a, GSK-3β and mTOR were analyzed by western blotting. Autophagosome formation was detected by adenovirus transfection.

RESULTS

In epidemiological analysis, low Klotho (≤295.9 pg/ml) was significantly associated with MACE risk (HR=2.266, 95 %CI 1.229-4.176). In experimental analysis, Klotho alleviated endothelial senescence and oxidative stress caused by Ang-II exposure; Klotho restored impaired autophagic flux to ameliorate Ang-II induced endothelial senescence; Ang-II activated Wnt3a/GSK-3β/mTOR signaling to inhibit autophagy, whereas Klotho restored autophagy through blockade of Wnt3a/GSK-3β/mTOR signaling; Klotho ameliorated endothelial senescence by suppressing Wnt3a/GSK-3β/mTOR pathway under Ang-II exposure.

CONCLUSIONS

Prognostic significance of Klotho in CAD is potentially ascribed to its anti-endothelial senescence effect via autophagic flux restoration by inhibiting Wnt3a/ GSK-3β/mTOR signaling.

Graphene oxide nanoarchitectures in cancer biology: Nano-modulators of autophagy and apoptosis

Nanotechnology is a growing field, with many potential biomedical applications of nanomedicine for the treatment of different diseases, particularly cancer, on the horizon. Graphene oxide (GO) nanoparticles can act as carbon-based nanocarriers with advantages such as a large surface area, good mechanical strength, and the capacity for surface modification. These nanostructures have been extensively used in cancer therapy for drug and gene delivery, photothermal therapy, overcoming chemotherapy resistance, and for imaging procedures. In the current review, we focus on the biological functions of GO nanoparticles as regulators of apoptosis and autophagy, the two major forms of programmed cell death. GO nanoparticles can either induce or inhibit autophagy in cancer cells, depending on the conditions. By stimulating autophagy, GO nanocarriers can promote the sensitivity of cancer cells to chemotherapy. However, by impairing autophagy flux, GO nanoparticles can reduce cell survival and enhance inflammation. Similarly, GO nanomaterials can increase ROS production and induce DNA damage, thereby sensitizing cancer cells to apoptosis. In vitro and in vivo experiments have investigated whether GO nanomaterials show any toxicity in major body organs, such as the brain, liver, spleen, and heart. Molecular pathways, such as ATG, MAPK, JNK, and Akt, can be regulated by GO nanomaterials, leading to effects on autophagy and apoptosis. These topics are discussed in this review to shed some lights towards the biomedical potential of GO nanoparticles and their biocompatibility, paving the way for their future application in clinical trials.

Shear stress leads to the dysfunction of endothelial cells through the Cav-1-mediated KLF2/eNOS/ERK signaling pathway under physiological conditions

To investigate the mechanism of shear stress on endothelial cell dysfunction for providing a theoretical basis for the reduction of arteriovenous fistula dysfunction. The in vitro parallel plate flow chamber was used to form different forces and shear stress to mimic the hemodynamic changes in human umbilical vein endothelial cells, and the expression and distribution of krüppel-like factor 2 (KLF2), caveolin-1 (Cav-1), p-extracellular regulated protein kinase (p-ERK), and endothelial nitric oxide synthase (eNOS) were detected by immunofluorescence and real-time quantitative polymerase chain reaction. With the prolongation of the shear stress action time, the expression of KLF2 and eNOS increased gradually, while the expression of Cav-1 and p-ERK decreased gradually. In addition, after cells were exposed to oscillatory shear stress (OSS) and low shear stress, the expression of KLF2, Cav-1, and eNOS decreased and the expression of p-ERK increased. The expression of KLF2 increased gradually with the prolongation of action time, but it was still obviously lower than that of high shear stress. Following the block of Cav-1 expression by methyl β-cyclodextrin, eNOS expression decreased, and KLF2 and p-ERK expression increased. OSS may lead to endothelial cell dysfunction by Cav-1-mediated KLF2/eNOS/ERK signaling pathway.

Mitochondria-endoplasmic reticulum contacts in sepsis-induced myocardial dysfunction

Mitochondrial and endoplasmic reticulum (ER) are important intracellular organelles. The sites that mitochondrial and ER are closely related in structure and function are called Mitochondria-ER contacts (MERCs). MERCs are involved in a variety of biological processes, including calcium signaling, lipid synthesis and transport, autophagy, mitochondrial dynamics, ER stress, and inflammation. Sepsis-induced myocardial dysfunction (SIMD) is a vital organ damage caused by sepsis, which is closely associated with mitochondrial and ER dysfunction. Growing evidence strongly supports the role of MERCs in the pathogenesis of SIMD. In this review, we summarize the biological functions of MERCs and the roles of MERCs proteins in SIMD.

Role of miR-199a-5p in the post-transcriptional regulation of ABCA1 in response to hypoxia in peritoneal macrophages

Hypoxia is a crucial factor contributing to maintenance of atherosclerotic lesions. The ability of ABCA1 to stimulate the efflux of cholesterol from cells in the periphery, particularly foam cells in atherosclerotic plaques, is an important anti-atherosclerotic mechanism. The posttranscriptional regulation by miRNAs represents a key regulatory mechanism of a number of signaling pathways involved in atherosclerosis. Previously, miR-199a-5p has been shown to be implicated in the endocytic and retrograde intracellular transport. Although the regulation of miR-199a-5p and ABCA1 by hypoxia has been already reported independently, the role of miR-199a-5p in macrophages and its possible role in atherogenic processes such us regulation of lipid homeostasis through ABCA1 has not been yet investigated. Here, we demonstrate that both ABCA1 and miR-199a-5p show an inverse regulation by hypoxia and Ac-LDL in primary macrophages. Moreover, we demonstrated that miR-199a-5p regulates ABCA1 mRNA and protein levels by directly binding to its 3'UTR. As a result, manipulation of cellular miR-199a-5p levels alters ABCA1 expression and cholesterol efflux in primary mouse macrophages. Taken together, these results indicate that the correlation between ABCA1-miR-199a-5p could be exploited to control macrophage cholesterol efflux during the onset of atherosclerosis, where cholesterol alterations and hypoxia play a pathogenic role.

Caveolin-1 and Its Functional Peptide CSP7 Affect Silica-Induced Pulmonary Fibrosis by Regulating Fibroblast Glutaminolysis

Exposure to silica is a cause of pulmonary fibrosis disease termed silicosis, which leads to respiratory failure and ultimately death. However, what drives fibrosis is not fully elucidated and therapeutic options remain limited. Our previous RNA-sequencing analysis showed that the expression of caveolin-1 (CAV1) was downregulated in silica-inhaled mouse lung tissues. Here, we not only verified that CAV1 was decreased in silica-induced fibrotic mouse lung tissues in both messenger RNA and protein levels, but also found that CSP7, a functional peptide of CAV1, could attenuate pulmonary fibrosis in vivo. Further in vitro experiments revealed that CAV1 reduced the expression of Yes-associated protein 1(YAP1) and affected its nuclear translocation in fibroblasts. In addition, Glutaminase 1 (GLS1), a key regulator of glutaminolysis, was identified to be a downstream effector of YAP1. CAV1 could suppress the activity of YAP1 to decrease the transcription of GLS1, thereby inhibiting fibroblast activation. Taken together, our results demonstrated that CAV1 and its functional peptide CSP7 may be potential molecules or drugs for the prevention and intervention of silicosis.

Crucial Function of Caveolin-1 in Deoxynivalenol-Induced Enterotoxicity by Activating ROS-Dependent NLRP3 Inflammasome-Mediated Pyroptosis

Deoxynivalenol (DON) is one of the most pervasive contaminating mycotoxins in grain, and exposure to DON is known to cause acute and chronic intestinal damage. As the gut is the most important target organ of DON, it is essential to identify the pivotal molecules involved in DON-induced enterotoxicity as well as the potential regulatory mechanisms. In the present study, we found that DON treatment dramatically decreased the jejunal villus height and increased the crypt depth in mice. DON exposure induced oxidative stress and NLRP3 inflammasome activation while increasing the levels of pyroptosis-related factors GSDMD, ASC, Caspase-1 P20, and IL-1β and inflammatory cytokines IL-18, TNF-α, and IL-6. In vitro, 0.5-2 μM DON caused cytotoxicity and oxidative stress, as well as NLRP3-mediated pyroptosis in IPEC-J2 cells. Furthermore, DON treatment substantially improved the expression of Caveolin-1 (Cav-1) in vitro and in vivo. Interestingly, Cav-1 knockdown effectively attenuated DON-induced oxidative stress and NLRP3-mediated pyroptosis in IPEC-J2 cells. Meanwhile, treatment with the antioxidant NAC significantly alleviated DON-induced cytotoxicity and pyroptosis in IPEC-J2 cells. Likewise, after inhibiting NLRP3 inflammasome activation with the inhibitor MCC950, DON-induced cytotoxicity, pyroptosis, and inflammatory response were attenuated. However, NLRP3 inhibition did not affect Cav-1 expression. In conclusion, our study demonstrated that pyroptosis may be an underlying mechanism in DON-induced intestinal injury, and Cav-1 plays a pivotal role in DON-induced pyroptosis via regulating oxidative stress, which suggests a novel strategy to overcome DON-induced enterotoxicity.

Endothelial caveolin-1 regulates cerebral thrombo-inflammation in acute ischemia/reperfusion injury

BACKGROUND

Thrombo-inflammation is an important checkpoint that orchestrates infarct development in ischemic stroke. However, the underlying mechanism remains largely unknown. Here, we explored the role of endothelial Caveolin-1 (Cav-1) in cerebral thrombo-inflammation.

METHODS

The correlation between serum Cav-1 level and clinical outcome was analyzed in acute ischemic stroke patients with successful recanalization. Genetic manipulations by endothelial-specific adeno-associated virus (AAV) and siRNA were applied to investigate the effects of Cav-1 in thrombo-inflammation in a transient middle cerebral artery occlusion (tMCAO) model. Thrombo-inflammation was analyzed by microthrombosis formation, myeloid cell infiltration, and endothelial expression of adhesion molecules as well as inflammatory factors.

FINDINGS

Reduced circulating Cav-1, with the potential to predict microembolic signals, was more frequently detected in recanalized stroke patients without early neurological improvement. At 24 h after tMCAO, serum Cav-1 was consistently reduced in mice. Endothelial Cav-1 was decreased in the peri-infarct region. Cav-1^-/- endothelium, with prominent barrier disruption, displayed extensive microthrombosis, accompanied by increased myeloid cell inflammatory infiltration after tMCAO. Specific enhanced expression of endothelial Cav-1 by AAV-Tie1-Cav-1 remarkably reduced infarct volume, attenuated vascular hyper-permeability and alleviated thrombo-inflammation in both wild-type and Cav-1^-/- tMCAO mice. Transcriptome analysis after tMCAO further designated Rxrg as the most significantly changed molecule resulting from the knockdown of Cav-1. Supplementation of RXR-γ siRNA reversed AAV-Tie1-Cav-1-induced amelioration of thrombo-inflammation without affecting endothelial tight junction.

INTERPRETATION

Endothelial Cav-1/RXR-γ may regulate infarct volume and neurological impairment, possibly through selectively controlling thrombo-inflammation coupling, in cerebral ischemia/reperfusion.

FUNDING

This work was supported by National Natural Science Foundation of China.

CAV1 alleviated CaOx stones formation via suppressing autophagy-dependent ferroptosis

Background

Calcium oxalate (CaOx) is the most common type of kidney stone, but the mechanism of CaOx stones formation remains unclear. The injury of renal cells such as ferroptosis and autophagy has been considered a basis for stones formation.

Methods

We conducted transmission electron microscope (TEM), reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), and C11-BODIPY analysis to explore whether CaOx could induce autophagy-dependent ferroptosis in vivo and in vitro. To explore the possible mechanism, we conducted bioinformatic analysis of patients with or without CaOx stones, Western blot and qPCR were used to identify the different genes we found in bioinformatic analysis.

Results

In our study, we found that CaOx could induce autophagy-dependent ferroptosis no matter in vivo or in vitro, which might finally lead to urolithiasis. Bioinformatic analysis of the GSE73680 dataset indicated that the expression of caveolin-1 (CAV1) was higher in control patients than CaOx stone patients, the STRING database indicated that CAV1 might interact with low density lipoprotein receptro-related protein 6 (LRP6), Gene Set Enrichment Analysis (GSEA) showed that the WNT pathway positively associated with the control group while negatively related to the stone group, and LRP6 was the core gene of the WNT pathway. Western blot found that CAV1, LRP6, and Wnt/β-Catenin were decreased in Human Kidney2 (HK2) cells stimulated with CaOx. Furthermore, the WNT pathway was considered to be involved in autophagy and ferroptosis.

Conclusions

We presumed that CAV1 could ameliorate autophagy-dependent ferroptosis through the LRP6/Wnt/β-Catenin axis, and finally alleviate CaOx stone formation.

Low shear stress inhibits endothelial mitophagy via caveolin-1/miR-7-5p/SQSTM1 signaling pathway

BACKGROUND AND AIMS

Mitophagy plays a crucial role in mitochondrial homeostasis and is closely associated with endothelial function. However, the mechanism underlying low blood flow shear stress (SS), detrimental cellular stress, regulating endothelial mitophagy is unclear. This study aimed to investigate whether low SS inhibits endothelial mitophagy via caveolin-1 (Cav-1)/miR-7-5p/Sequestosome 1 (SQSTM1) signaling pathway.

METHODS

Low SS in vivo modeling was induced using a perivascular SS modifier implanted in the carotid artery of mice. In vitro modeling, low and physiological SS (4 and 15 dyn/cm2, respectively) were exerted on human aortic endothelial cells using a parallel plate chamber system.

RESULTS

Compared with physiological SS, low SS significantly inhibited endothelial mitophagy shown by down-regulation of SQSTM1, PINK1, Parkin, and LC 3II expressions. Deficient mitophagy deteriorated mitochondrial dynamics shown by up-regulation of Mfn1 and Fis1 expression and led to decreases in mitochondrial membrane potential. Cav-1 plays a bridging role in the process of low SS inhibiting mitophagy. The up-regulated miR-7-5p expression induced by low SS was suppressed after Cav-1 was silenced. The results of dual-luciferase reporter assays showed that miR-7-5p targeted inhibiting the SQSTM1 gene. Oxidative stress reaction shown by the elevation of reactive oxygen species and O2●- and endothelial dysfunction by the decrease in nitric oxide and the increase in macrophage chemoattractant protein-1 were associated with the low SS inhibiting endothelial mitophagy process.

CONCLUSIONS

Cav-1/miR-7-5p/SQSTM1 signaling pathway was the mechanism underlying low SS inhibiting endothelial mitophagy that involves mitochondrial homeostasis impairment and endothelial dysfunction.

Functional characterization of nutraceuticals using spectral clustering: Centrality of caveolae-mediated endocytosis for management of nitric oxide and vitamin D deficiencies and atherosclerosis

It is well recognized that redox imbalance, nitric oxide (NO), and vitamin D deficiencies increase risk of cardiovascular, metabolic, and infectious diseases. However, clinical studies assessing efficacy of NO and vitamin D supplementation have failed to produce unambiguous efficacy outcomes suggesting that the understanding of the pharmacologies involved is incomplete. This raises the need for using systems pharmacology tools to better understand cause-effect relationships at biological systems levels. We describe the use of spectral clustering methodology to analyze protein network interactions affected by a complex nutraceutical, Cardio Miracle (CM), that contains arginine, citrulline, vitamin D, and antioxidants. This examination revealed that interactions between protein networks affected by these substances modulate functions of a network of protein complexes regulating caveolae-mediated endocytosis (CME), TGF beta activity, vitamin D efficacy and host defense systems. Identification of this regulatory scheme and the working of embedded reciprocal feedback loops has significant implications for treatment of vitamin D deficiencies, atherosclerosis, metabolic and infectious diseases such as COVID-19.

Role of Caveolin-1 in Sepsis – A Mini-Review

Sepsis is a generalized disease characterized by an extreme response to a severe infection. Moreover, challenges remain in the diagnosis, treatment and management of septic patients. In this mini-review we demonstrate developments on cellular pathogenesis and the role of Caveolin-1 (Cav-1) in sepsis. Studies have shown that Cav-1 has a significant role in sepsis through the regulation of membrane traffic and intracellular signaling pathways. In addition, activation of apoptosis/autophagy is considered relevant for the progression and development of sepsis. However, how Cav-1 is involved in sepsis remains unclear, and the precise mechanisms need to be further investigated. Finally, the role of Cav-1 in altering cell permeability during inflammation, in sepsis caused by microorganisms, apoptosis/autophagy activation and new therapies under study are discussed in this mini-review.

Deciphering the relationship between caveolae-mediated intracellular transport and signalling events

The caveolae-mediated transport across polarized epithelial cell barriers has been largely deciphered in the last decades and is considered the second essential intracellular transfer mechanism, after the clathrin-dependent endocytosis. The basic cell biology knowledge was supplemented recently, with the molecular mechanisms beyond caveolae generation implying the key contribution of the lipid-binding proteins (the structural protein Caveolin and the adapter protein Cavin), along with the bulb coat stabilizing molecules PACSIN-2 and Eps15 homology domain protein-2. The current attention is focused also on caveolae architecture (such as the bulb coat, the neck, the membrane funnel inside the bulb, and the associated receptors), and their specific tasks during the intracellular transport of various cargoes. Here, we resume the present understanding of the assembly, detachment, and internalization of caveolae from the plasma membrane lipid raft domains, and give an updated view on transcytosis and endocytosis, the two itineraries of cargoes transport via caveolae. The review adds novel data on the signalling molecules regulating caveolae intracellular routes and on the transport dysregulation in diseases. The therapeutic possibilities offered by exploitation of Caveolin-1 expression and caveolae trafficking, and the urgent issues to be uncovered conclude the review.

Endothelial shear stress signal transduction and atherogenesis: From mechanisms to therapeutics

Atherosclerotic vascular disease and its complications are among the top causes of mortality worldwide. In the vascular lumen, atherosclerotic plaques are not randomly distributed. Instead, they are preferentially localized at the curvature and bifurcations along the arterial tree, where shear stress is low or disturbed. Numerous studies demonstrate that endothelial cell phenotypic change (e.g., inflammation, oxidative stress, endoplasmic reticulum stress, apoptosis, autophagy, endothelial-mesenchymal transition, endothelial permeability, epigenetic regulation, and endothelial metabolic adaptation) induced by oscillatory shear force play a fundamental role in the initiation and progression of atherosclerosis. Mechano-sensors, adaptor proteins, kinases, and transcriptional factors work closely at different layers to transduce the shear stress force from the plasma membrane to the nucleus in endothelial cells, thereby controlling the expression of genes that determine cell fate and phenotype. An in-depth understanding of these mechano-sensitive signaling cascades shall provide new translational strategies for therapeutic intervention of atherosclerotic vascular disease. This review updates the recent advances in endothelial mechano-transduction and its role in the pathogenesis of atherosclerosis, and highlights the perspective of new anti-atherosclerosis therapies through targeting these mechano-regulated signaling molecules.