Mechanism of miR-199a/MTOR in myocardial fibrosis and left ventricular hypertrophy in spontaneous hypertensive rats
Hao Dan
Zhou Daliang
Yu Xiying
Zhang Chunru
Wei Lin.
Abstract：To study the influence of miR-199a and mammalian target of rapamycin (mTOR) on myocardial fibrosis and left ventricular hypertrophy (LVH) in spontaneous hypertensive rats (SHR), and discuss possible mechanism. Methods Normal male WKY rats were chosen into normal group (n=15), and SHR were randomly divided into SHR group and inhibitor group (each n=15). The normal group and SHR group were given caudal vein injection of normal saline, and inhibitor group was given caudal vein injection of miR-199a inhibitor. The blood pressure was determined by using caudal artery volume method in 3 groups. LVEDD/LVESD, LVPWT, IVST, FS and LVEF were detected by using echocardiogram. The heart function indexes (+dp/dt, -dp/dt, LVEDP, LVM and LVMI) were recorded and calculated by using right common carotid artery intubation. The severity of myocardial fibrosis was observed after HE and Masson staining. The mRNA and protein expressions of myocardial miR-199a and mTOR were detected by using qRT-PCR and Western blotting assay. The correlation between miR-199a and mTOR was reviewed by using Pearson correlation analysis. H9c2 cells were cultivated in vitro and transfected with miR-199a mimic leading to over-expression. The mRNA and protein expressions of miR-199a and mTOR were detected by using qRT-PCR and Western blotting assay. Whether or not mTOR was the target gene of miR-199a was detected by using luciferase activity. Results LVEDD, LVESD, IVST and LVPWT increased in SHR group compared with normal group (all P<0.05), and decreased in inhibitor group compared with SHR group (all P<0.05). LVM, LVMI and LVEDP increased and +dp/dt and -dp/dt decreased in SHR group compared with normal group (all P<0.05), and LVM, LVMI and LVEDP decreased and +dp/dt and -dp/dt increased in inhibitor group compared with SHR group (all P<0.05). The pathologic scores and myocardial collagen fiber ratio increased in SHR group compared with normal group (all P<0.05), and decreased in inhibitor group compared with SHR group (all P<0.05). The expression of miR-199a mRNA increased and mTOR mRNA expression decreased in SHR group compared with normal group (all P<0.05). The expression of miR-199a mRNA decreased and mTOR mRNA expression increased in inhibitor group compared with SHR group (all P<0.05). The results of Pearson correlation analysis showed that miR-199a was significantly and negatively correlated to mTOR mRNA and protein expressions (r=-4.873, P=0.000; r=-5.126, P=0.000). The expression of miR-199a mRNA increased and mTOR mRNA and protein expressions decreased in miR-199a over-expression group compared with blank control group and negative transfection group (all P<0.05). The luciferase activity decreased in 3’UTR-Wt transfected cells in miR-199a over-expression group compared with negative transfection group (P<0.05), and had no significant difference in 3’UTR-Mut transfected cells between miR-199a over-expression group and negative transfection group (P<0.05). Conclusion The up-regulated expression of miR-199a may be related to myocardial fibrosis and LVH, and targeted-regulation of mTOR is possibly the mechanism.
Keywords：Spontaneous hypertensionMyocardial fibrosisLeft ventricular hypertrophyMiR-199aMammalian target of rapamycinRats
Publication Date：2019-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：6( 85-89,93 )