Bestrophin3 Deficiency in Vascular Smooth Muscle Cells Activates MEKK2/3-MAPK Signaling to Trigger Spontaneous Aortic Dissection.

BACKGROUND: Aortic dissection (AD) is a fatal cardiovascular disorder without effective medications due to unclear pathogenic mechanisms. Bestrophin3 (Best3), the predominant isoform of bestrophin family in vessels, has emerged as critical for vascular pathological processes. However, the contribution of Best3 to vascular diseases remains elusive. METHODS: Smooth muscle cell-specific and endothelial cell-specific Best3 knockout mice (Best3SMKO and Best3ECKO, respectively) were engineered to investigate the role of Best3 in vascular pathophysiology. Functional studies, single-cell RNA sequencing, proteomics analysis, and coimmunoprecipitation coupled with mass spectrometry were performed to evaluate the function of Best3 in vessels. RESULTS: Best3 expression in aortas of human AD samples and mouse AD models was decreased. Best3SMKO but not Best3ECKO mice spontaneously developed AD with age, and the incidence reached 48% at 72 weeks of age. Reanalysis of single-cell transcriptome data revealed that reduction of fibromyocytes, a fibroblast-like smooth muscle cell cluster, was a typical feature of human ascending AD and aneurysm. Consistently, Best3 deficiency in smooth muscle cells decreased the number of fibromyocytes. Mechanistically, Best3 interacted with both MEKK2 and MEKK3, and this interaction inhibited phosphorylation of MEKK2 at serine153 and MEKK3 at serine61. Best3 deficiency induced phosphorylation-dependent inhibition of ubiquitination and protein turnover of MEKK2/3, thereby activating the downstream mitogen-activated protein kinase signaling cascade. Furthermore, restoration of Best3 or inhibition of MEKK2/3 prevented AD progression in angiotensin II-infused Best3SMKO and ApoE-/- mice. CONCLUSIONS: These findings unveil a critical role of Best3 in regulating smooth muscle cell phenotypic switch and aortic structural integrity through controlling MEKK2/3 degradation. Best3-MEKK2/3 signaling represents a novel therapeutic target for AD.

MiR-155-5p promotes metastasis and epithelial-mesenchymal transition of renal cell carcinoma by targeting apoptosis-inducing factor.

BACKGROUND: Although renal cell carcinoma remains one of the most malignant cancers, our understanding of progression and recurrence of this disease is limited. The present study explored the precise role of miR-155-5p in renal cancer metastasis. METHODS: The expression of miR-155-5p in renal carcinoma clinical tissues and cells was determined using quantitative real time-polymerase chain reaction. The role of miR-155-5p on tumor cell growth were examined using CCK-8 and colony formation assays. Transwell assay was utilized to identify the role of miR-155-5p on the invasion and migration of renal cancer cells. Markers of epithelial-mesenchymal transition were determined using western blot. The in vivo effects of miR-155-5p on renal cancer cell growth, apoptosis, and metastasis were explored using xenograft mice. Luciferase reporter assay was performed to identify the potential target of miR-155-5p. RESULTS: Levels of miR-155-5p were significantly elevated in renal cancer tissues and cell lines. Suppression of miR-155-5p decreased the growth, colony formation, migration, and invasiveness of renal cancer cells. In contrast, overexpression of miR-155-5p led to opposite effects on renal cancer cells. Mechanically, the apoptosis-inducing factor was identified as the target of miR-155-5p. Interference of miR-155-5p significantly increased mRNA and protein expression of the apoptosis-inducing factor, whereas overexpression of miR-155-5p remarkably suppressed the apoptosis-inducing factor levels in renal cancer cells. The xenograft model identified that suppression of miR-155-5p restrained tumor growth and promoted apoptosis, whereas overexpression of miR-155-5p decreased apoptosis and accelerated tumor growth. Moreover, the number of lung metastasis nodules were decreased following injection with anti-miR-155-5p transfected cells, whereas the nodules were remarkably increased after overexpression of miR-155-5p. In addition, in vitro and in vivo assays both confirmed that suppression of miR-155-5p increased the expression of E-cadherin and decreased levels of N-cadherin and Snail, whereas overexpression of miR-155-5p accelerated epithelial-mesenchymal transition progression in renal cancer cells. CONCLUSION: These findings demonstrate that miR-155-5p enhances metastasis and epithelial-mesenchymal transition by targeting the apoptosis-inducing factor, suggesting that miR-155-5p represents a novel therapeutic target for renal cancer.

MiR-302a Limits Vascular Inflammation by Suppressing Nuclear Factor-κ B Pathway in Endothelial Cells.

The inflammatory response of endothelial cells accelerates various vascular diseases. MicroRNAs (miRNAs) participate in diverse cellular processes during inflammation. In the present study, we found that miR-302a is an effective suppressor of vascular inflammation in endothelial cells. It was revealed that miR-302a exhibited a lower level in a lipopolysaccharide (LPS)-induced mouse model and in patients with vascular inflammatory disease. Genetic haploinsufficiency of miR-302 aggravated the LPS-induced vascular inflammatory response in mice, and overexpression of miR-302a attenuated vascular inflammation in mice. Furthermore, overexpression of miR-302a inhibited the synthesis and secretion of adhesion factors in endothelial cells, and suppressed the adhesion of monocytes to endothelium. In the study of molecular mechanism, we found that miR-302a relieved vascular inflammation mainly by regulating the nuclear factor kappa-B (NF-κB) pathway in endothelial cells. The results showed that interleukin-1 receptor-associated kinase4 (IRAK4) and zinc finger protein 91 (ZFP91) were the binding targets of miR-302a. MiR-302a prevented the nuclear translocation of NF-κB by inhibiting phosphorylation of IκB kinase complex ß (IKKß) and inhibitors of κBα (IκBα) via targeting IRAK4. In addition, miR-302a downregulated the expression of NF-κB by directly binding with ZFP91. These findings indicate that miR-302a negatively regulates inflammatory responses in the endothelium via the NF-κB pathway and it may be a novel target for relieving vascular inflammation.