miR-145 attenuates phenotypic transformation of aortic vascular smooth muscle cells to prevent aortic dissection

BACKGROUND

miR-145 is closely related to vascular smooth muscle cells (VSMC) phenotype transformation; however, the regulatory mechanisms through which miR-145 regulates the VSMC phenotype transformation under mechanical stretching are unclear. In this study, we evaluated the roles of miR-145 in VSMCs subjected to mechanical stretching in aortic dissection (AD).

METHODS

The expression of miR-145 in the aortic vessel wall of model animals and patients with AD was analyzed by quantitative polymerase chain reaction. miR-145-related protein-protein interaction networks and Wikipathways were used to analyze VSMC phenotypic transformation pathways regulated by miR-145. We used gain- and loss-of-function studies to evaluate the effects of miR-145 on VSMC differentiation under mechanical stretch induction and assessed whether Krüppel-like factor 4 (KLF4) was regulated by miR-145 in the aorta under mechanical stretch conditions.

RESULTS

miR-145 was abundantly expressed in the walls of the normal human aorta, but was significantly downregulated in animal models and the walls of patients with dissection. We found that contractile phenotype-related proteins were downregulated in VSMCs subjected to mechanical stretching, whereas the expression of secreted phenotype-related proteins increased. miR-145 overexpression also downregulated contractile phenotype-related proteins in VSMCs and suppressed upregulation of phenotype-related proteins. Finally, under mechanical stretching, KLF4 expression was significantly increased in VSMCs, and overexpression of miR-145 blocked this effect.

CONCLUSION

Our results confirmed that mechanical stretch-induced phenotypic transformation of VSMCs to promote AD via upregulation of KLF4; this mechanism was regulated by miR-145, which directly modulated KLF4 expression and VSMC differentiation.

MicroRNA-145, Wnt3a, and Dab2 Genes Expression Changes of the Cardiomyocytes in Hypercholesterolemic Rats Exposed to the Aerobic Training

The current study aimed to investigate the effect of a 12-week endurance training (ET) on microRNA-145 (miR-145) changes and Wnt3a and Dab2 cardiomyocytes genes expression of hypercholesterolemic Wistar male rats. Thirty-two male Wistar rats (191.2±19 g, 6-8 weeks age) were randomly assigned into the aerobic exercise-normal nutrition (ANN; n=8), hypercholesterolemic (HCL; n=8), aerobic exercise- hypercholesterolemic (ACL; n=8), and normal nutrition (NN; n=8). Hypercholesterolemia was created by adding 1% cholesterol to the food of the HCL and ACL rats. ET was done five sessions per week on nonconsecutive days for 12 weeks. Twenty-four hours after the last training session, the rats were killed, and the cardiomyocytes were removed. The expression of miR-145, Wnt3a, and Dab2 genes in cardiomyocytes was assessed by real time PCR method. The expression of miR-145 significantly increased in the ANN group in comparison with other groups (P = 0.001). Also, Dab2 gene expression significantly decreased in the ANN group in comparison with ACL (P = 0.001) and HCL (P = 0.001) groups. The results also showed that the Wnt3a in the ANN group was significantly different from NN (p=0.001), ACL, and HCL (p=0.001) groups. It can be concluded that aerobic training and cholesterol-rich foods play an essential regulatory role in the expression of miR-145, Dab2, and Wnt3a genes. However, cholesterol-rich foods appear to play a more significant regulatory role than aerobic exercise training.

miR145 Regulates the Proliferation and Apoptosis of Rat Vascular Endothelial Cells under Hyperglycemia by Targeting the ANGPT2 Gene and Involving the NFκB Signaling Pathway

PURPOSE

A majority of diabetes mellitus patients with disturbances of glucose metabolism present with vascular complications. This study aimed to explore regulatory mechanisms of miR145 and its potential target gene ANGPT2 on diabetic vasculopathy under hyperglycemia.

METHODS

Based on the fact that miR145 is detected in rat aortic endothelial cells (RAECs) under hyperglycemia, RAECs were transfected with miR145 mimics/inhibitor for further confirmation. RAEC proliferation was detected with CCK8 assays, and cell apoptosis and CD34⁺-cell population with annexinV-PI staining and anti-CD34FITC on flow cytometry, respectively. Then, qPCR and Western blot were applied to detect mRNA and protein expression of ANGPT2 and involved pathway factor NFκB p65. Subsequently, dual luciferase-reporter gene analysis was utilized to verify whether miR145 acted directly upon the 3'UTR of ANGPT2 mRNA.

RESULTS

The ANGPT2 gene was confirmed to be a direct target of miR145. miR145 mimics markedly downregulated the expression of ANGPT2 and NFκB p65, boosted the percentage of the CD34⁺ phenotype, and promoted proliferation and suppressed apoptosis of RAECs under hyperglycemia.

CONCLUSION

miR145 might regulate the viability of RAECs via targeting ANGPT2 and involving NFκB signaling to exert a protective effect on diabetic vasculature.

Hexim1 heterozygosity stabilizes atherosclerotic plaque and decreased steatosis in ApoE null mice fed atherogenic diet

Hexim-1 is an inhibitor of RNA polymerase II transcription elongation. Decreased Hexim-1 expression in animal models of chronic diseases such as left ventricular hypertrophy, obesity and cancer triggered significant changes in adaptation and remodeling. The main aim of this study was to evaluate the role of Hexim1 in lipid metabolism focused in the progression of atherosclerosis and steatosis. We used the C57BL6 apolipoprotein E (ApoE null) crossed bred to C57BL6Hexim1 heterozygous mice to obtain ApoE null - Hexim1 heterozygous mice (ApoE-HT). Both ApoE null backgrounds were fed high fat diet for twelve weeks. Then, we evaluated lipid metabolism, atherosclerotic plaque formation and liver steatosis. In order to understand changes in the transcriptome of both backgrounds during the progression of steatosis, we performed Affymetrix mouse 430 2.0 microarray. After 12 weeks of HFD, ApoE null and ApoE-HT showed similar increase of cholesterol and triglycerides in plasma. Plaque composition was altered in ApoE-HT. Additionally, liver triglycerides and steatosis were decreased in ApoE-HT mice. Affymetrix analysis revealed that decreased steatosis might be due to impaired inducible SOCS3 expression in ApoE-HT mice. In conclusion, decreased Hexim-1 expression does not alter cholesterol metabolism in ApoE null background after HFD. However, it promotes stable atherosclerotic plaque and decreased steatosis by promoting the anti-inflammatory TGFβ pathway and blocking the expression of the inducible and pro-inflammatory expression of SOCS3 respectively.