OBJECTIVETo investigate the role of miRNA-199a on cardiac hypertrophy.

METHODS(1) Male Sprague-Dawley rats were subjected to pressure overload induced by abdominal aortic constriction (AAC, n = 6) and quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the change of microRNAs (miRNAs). (2) Neonatal rat ventricular myocytes were isolated from 2-day old Sprague-Dawley rats. The myocytes were divided into two groups: adenovirus miRNA-199a (Ad-miRNA-199a) or adenovirus vector (Ad-vector). They were transfected in cardiomyocytes for 48 h using Lipofectamine 2000. qRT-PCR was used to detect the change of myocardial hypertrophy markers α-myosin heavy chain (αMHC, myh6), β-myosin heavy chain (βMHC, myh7) and atrial natriuretic peptide (ANP, Nppa). Software Axio Vision was used to detect the change of cardiomyocytes surface areas. (3) Neonatal rat ventricular myocytes were divided into two groups: antisense oligonucleotide-miRNA-199a (As-miRNA-199a) and scramble oligonucleotides (As-ctl). They were transfected to cardiomyocytes respectively for 48 h. qRT-PCR was used to detect the change of miRNA-199a. (4) Neonatal rat ventricular myocytes were divided into four groups: A: control (ctl), B: phenylephrine (PE), C: PE + As-ctl, D: PE + As-miRNA-199a. qRT-PCR was used to detect the change of myh6, myh7 and Nppa. Software Axio Vision was used to detect the change of cardiomyocytes surface areas.

RESULTS(1) qRT-PCR results showed that miRNA-1, miRNA-133, miRNA-181a and miRNA-499 were significantly decreased, while the miRNA-199a was significantly increased at 1 week post AAC hearts compared with the sham group. (2) qRT-PCR results showed that miRNA-199a and myh7 were increased and myh6 was decreased significantly in Ad-miRNA-199a group compared with Ad-vector group. The cardiomyocytes surface area was increased in Ad-miRNA-199a group detected by immunofluorescence. (3) qRT-PCR results showed that miRNA-199a was significantly decreased in As-miRNA-199a group compared with Ad-vector group. (4) The Nppa and myh7 were significantly increased and myh6 was decreased in cardiomyocytes stimulated by PE for 48 h. The cardiomyocytes surface area determined by immunofluorescence was increased in PE + As-miRNA-199a groups compared with PE + As-ctl groups.

CONCLUSIONmiRNA-199a may play a regulatory role in cardiac hypertrophy.