Cardiac hypertrophy is positively regulated by long non-coding RNA PVT1

Abstract

The aim of this study was to determine whether long non-coding RNA PVT1 can participate in the regulation of cardiac hypertrophy. A C57BL/6 mouse cardiac hypertrophic model was established using transverse aortic constriction (TAC). The animals subjected to sham operation were used as controls. Transcripts of PVT1 were analyzed in hearts of model and sham control groups after TAC for 4 weeks using quantitative real-time PCR (qRT-PCR). Additionally, to investigate whether PVT1 was involved in cardiac hypertrophy, 1 μM angiotensin II (Ang II) was used to induce hypertrophy and PVT1 siRNA was performed in the cultured neonatal mouse cardiac cardiomyocytes. Cell size was measured by cell surface area and total protein content analyses in response to Ang II treatment. Moreover, some hypertrophic markers including atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), and beta-myosin heavy chain (β-MHC) were also quantified using qRT-PCR. As a result, PVT1 was up-regulated by 2.5-fold (P<0.05) in hypertrophic hearts after TAC for 4 weeks as compared to sham group. In addition, siRNA of endogenous PVT1 in cardiomyocytes significantly reduced (P<0.05) Ang II-induced increase of cell size in terms of cell surface area (by 5.6-fold) and total protein content (by 23.0%). PVT1 siRNA also obviously attenuated Ang II-induced ANP and β-MHC expression by 40.9% and 41.5%, respectively (P<0.05), but had no effect on BNP mRNA expression. Our results demonstrated that PVT1 was essential for the maintenance of cell size of cardiomyocytes and might play a role in the regulation of cardiac hypertrophy.

Keywords: Cardiac hypertrophy; PVT1; cardiomyocytes; long non-coding RNA; transverse aortic constriction.

Figure 1

The expression level of PVT1 in hearts of transverse aortic constriction (TAC) mouse model and sham control after 4 weeks (n = 4 for each group). The different letters (a and b) indicated significant differences (P < 0.05).

Figure 2

PVT1 siRNA rescued hypertrophic responses in cardiomyocytes. A. After 72 h of culture, relative fold change of PVT1 expression in the cultured neonatal mouse cardiac cardiomyocyte of starvation group, (starvation + Ang II) group and (starvation + Ang II + siRNA) group vs. control group, respectively. B. Representative photograph of cardiomyocytes transfected with PVT1 siRNA after Ang II treatment (Hoechst 33342 staining). C. Cell surface areas of the cardiomyocytes were measured using Image J software (n = 100). Scale bars, 20 μm. The different letters (a, b and c) indicated significant differences (P < 0.05).

Figure 3

After 72 h of culture, cardiomyocytes hypertrophy was assessed by total protein content measurement in all groups by Bradford Assay. The different letters (a, b and c) indicated significant differences (P < 0.05).

Figure 4

After 72 h of culture, relative fold change of (A) ANP, (B) BNP and (C) β-MHC expression in the cultured neonatal mouse cardiac cardiomyocyte of treatment groups vs. control group, respectively. The different letters (a, b and c) indicated significant differences (P < 0.05). ANP: atrial natriuretic peptide; BNP: B-type natriuretic peptide; β-MHC: beta-myosin heavy chain.