Chronic hypoxia is the most common cause of secondary pulmonary hypertension, for which the mechanisms are still unclear. Recent studies implicated an important role for microRNAs (miRNAs) in hypoxia-mediated responses in various cellular processes, including cell apoptosis and proliferation. Therefore, we hypothesized that these regulatory molecules might be implicated in the etiology of hypoxic pulmonary hypertension. Here we show that miRNA-328, a posttranscriptional regulator, was drastically downregulated in the pulmonary artery (PA) after a hypoxic assault. PA rings, Western blot, quantitative real-time PCR, in situ hybridization, and luciferase assay were used to investigate the role of miRNA-328 in hypoxic pulmonary hypertension. We found that hypoxia produced a significant inhibition of miRNA-328 expression, which was involved in PA vasoconstriction and remodeling. Overexpressing miRNA-328 in the transgenic mice remarkably decreased the right ventricular systolic pressure and PA wall thickness under both normoxia and hypoxia. MiRNA-328 inhibited L-type calcium channel-α1C expression through a miRNA-328 binding site within the 3' untranslational region of L-type calcium channel-α1C. The L-type calcium channel-α1C inhibition attenuated the PA response to KCl. Furthermore, miRNA-328 suppressed the insulin growth factor 1 receptor, ultimately leading to apoptosis of pulmonary arterial smooth muscle cells. The posttranscriptional repression of L-type calcium channel-α1C and insulin growth factor 1 receptor was further confirmed by luciferase reporter assay. These results showed that miRNA-328, an important protecting factor, plays a significant role in PA constriction and remodeling by regulating multiple gene targets in hypoxic pulmonary hypertension.
Hypertension 03/2012; 59(5):1006-13. DOI:10.1161/HYPERTENSIONAHA.111.185413 · 7.63 Impact Factor
08/2011; 10(4):344-347. DOI:10.3724/SP.J.1264.2011.00015
To investigate the effects of tissue inhibitor-3 of matrix metalloproteinases (TIMP-3) gene-transfected vascular smooth muscle cells (VSMCs) transplantation on heart structure after acute myocardial infarction (AMI) in rats and to explore the potential mechanisms.
Sixty-one female Wistar rats were produced AMI models by ligating the descending left coronary artery. Fifty-four rats were survived and divided into 3 groups randomly (n= 18): 0.5 ml PBS containing 1 x 10(6) TIMP-3 gene-transfected VSMCs (group A), 1 x 10(6) VSMCs (group B) or 0.5 ml PBS without cell(group C) were injected into the ischemic myocardium immediately. Ischemic myocardium samples were harvested at 1 week after operation. The heart structure was observed through the tissue morphologic examination. The activity of TIMP-3 gene-transfected VSMCs were measured by immunohistochemical method. Proteins of TIMP-3 and matrix metalloproteinase 9(MMP-9) were determined by Western blot.
VSMCs were cultivated and had a high purity (98%). TIMP-3 gene was transfected into VSMCs successfully. One week after operation in groups A, B and C, the average percentage of infarction myocardium size and left ventricle free wall area were 28.73%+/-1.56%, 39.63%+/-1.84% and 46.32%+/-2.16% separately. Group A was significantly lower than groups B and C (P<0.01), group B was significantly lower than group C (P<0.01). In groups A, B and C the average left ventricle volume indexes were 5.27+/-0.21 mm3/g, 6.69+/-0.34 mm3/g and 9.67+/-0.88 mm3/g respectively. Group A was significantly smaller than groups B and C (P<0.01), group B was significantly smaller than group C (P<0.01). The immunohistochemical observation confirmed that the implanted VSMCs and TIMP-3 gene were survival in ischemic area. The protein content of TIMP-3 in ischemic myocardium was significantly higher in group A (300 704.8+/-3 692.8) than in groups B and C (195548.8+/-3014.2, 177991.1+/-2502.1) (P<0.01), the protein content of MMP-9 in ischemic myocardium was significantly lower in group A (594827.4+/-5708.5) than in groups B and C (921461.4+/-8887.4, 1044445.0+/-8788.6) (P<0.01).
Implanted TIMP-3 gene transfected VSMCs in ischemic myocardium can conspicuously reduce the myocardium remodeling after AMI.
Zhongguo xiu fu chong jian wai ke za zhi = Zhongguo xiufu chongjian waike zazhi = Chinese journal of reparative and reconstructive surgery 06/2007; 21(5):512-6.