SP1-SYNE1-AS1-miR-525-5p Feedback Loop Regulates Ang-II-induced Cardiac Hypertrophy

Cardiac hypertrophy (CH) has become a huge threat to human health. Recent years, long noncoding RNAs (lncRNAs) have been studied in human diseases, including CH. According to bioinformatics analysis, 10 lncRNAs possibly involved in the progression of CH were screened out. Among which, lncRNA SYNE1 antisense RNA 1 (SYNE1-AS1) could be upregulated by Angiotensin II (Ang-II) in cardiomyocytes. Thus, we chose SYNE1-AS1 to do further study. To identify the biological function of SYNE1-AS1 in CH, SYNE1-AS1 was silenced in Ang-II-induced cardiomyocytes. Results of immunofluorescence staining demonstrated that increased cell surface area in Ang-II-induced cardiomyocytes was reduced by SYNE1-AS1 knockdown. Moreover, the hypertrophic responses were attenuated by SYNE1-AS1 knockdown. Mechanically, SYNE1-AS1 positively regulated Sp1 transcription factor (SP1) by sponging microRNA-525-5p (miR-525-5p). On the basis of previous reports, SP1 can transcriptionally activate lncRNAs. Therefore, we investigated the interaction between SP1 and SYNE1-AS1 promoter. Intriguingly, SYNE1-AS1 was activated by SP1. At last, rescue assays demonstrated the function of SP1-SYNE1-AS1 axis in CH. In conclusion, SP1-induced upregulation of lncRNA SYNE1-AS1 promoted CH via miR-525-5p/SP1 axis.