Expression of Cx43-related microRNAs in patients with tetralogy of Fallot.

BACKGROUND Abnormal expression of connexin 43 (Cx43) has been reported to play an important role in the development of conotrunccal anomalies. However, less is known about the underlying reason for its abnormal expression. MicroRNAs (miRNAs), as an important part of gene expression regulation, have been implicated in some cardiac diseases. This study aimed to investigate the expression of Cx43 and its related miRNAs in patients with tetralogy of Fallot (TOF), and illustrate the potential role of abnormal miRNAs regulation to Cx43 expression in the pathology of TOF. METHODS Real-time polymerase chain reaction (PCR) was used to detect the expression of Cx43 and 10 Cx43-related miRNAs in the myocardium from 30 TOF patients and 10 normal controls. Immunohistochemistry was used to detect Cx43 protein expression. Putative miRNA binding sites in the 3'UTR of Cx43 were examined in 200 TOF patients and 200 healthy individuals, using Sanger sequencing, to exclude sequence variations resulting in binding difficulties of miRNAs. RESULTS Cx43 mRNA and protein expression in the myocardium tissue was significantly increased in TOF patients. The expression of MiR-1 and 206 was significantly decreased in the TOF patients as compared with the controls (P<0.05). No obvious difference was observed in the expression of the other 7 miRNAs between the TOF patients and controls (P>0.05). No meaningful sequence variation was detected in the putative miR1/206 binding sites in the 3'UTR of Cx43. CONCLUSIONS This study indicated that miR-1 and 206 is down-regulated in TOF patients, which may cause an up-regulation of Cx43 protein's synthesis. It provided a clue that miR-1 and 206 might be involved in the pathogenesis of TOF, additional experiments are needed to determine if in fact, miR-1 and 206 contribute substantially to TOF.