Anti-apoptotic function of herpes simplex virus -2 latency-associated transcript RL1 sequence and screening of its encoded micro RNAs.

Background The latency-associated transcript ( LAT) gene of herpes simplex virus ( HSV)-2 is the only detectable viral gene expressed during latent infection in neurons. LAT inhibits apoptosis and maintains latency by promoting the survival of infected neurons. However, whether LAT functions during HSV-2 infection via its encoded RNAs or via its encoded proteins remain unknown. Increasing evidence has indicated that LAT is likely to functionally promote the establishment of latent infection via LAT-encoded micro RNAs (mi RNAs). Aim To explore whether the RL1 fragment of the five adjacent mi RNAs has an effect on cell apoptosis, then provide supporting evidence to elucidate the potential role of these mi RNAs and to aid screening of their cellular targets. Methods A number of techniques, including MTT assay, flow cytometry and DNA ladder analysis, were used to verify the role of the RL1 fragment and the contribution of the individual mi RNAs to the anti-apoptotic effect. Results Five mi RNAs (miR-H3, miR-H4 -3p, miR-H4 -5p, miR-H24 and miR-H19) were detected by quantitative PCR in PC12 cells stably expressing RL1 after pEGFP- RL1 plasmid transfection in vitro. The data indicated that expression of HSV-2 LAT RL1 seems to provide protection against apoptosis of PC12 cells induced by ActD. Antisense mi RNAs specifically inhibiting these five mi RNAs could efficiently reduce their expression. Transfection of antisense-miR-H3, antisense-miR-H4 -5p and antisense-miR-H19 into PC12 cells stably expressing RL1 were able to partly reverse the anti-apoptotic effect of these mi RNAs. Conclusions These findings indicate that the apoptotic role of the RL1 fragment is likely to be related to overexpression of miR-H3, miR-H4 -5p and miR-H19 in PC12 cells. [ABSTRACT FROM AUTHOR]