Abstract 10616: Mir-128 Targets E2f3 to Regulate Cardiomyocyte Cell Cycle Re-entry
Background and Objective: Transcription factor E2F3 plays an essential role in cardiac development. Despite its critical importance in cell proliferation, the precise mechanism by which E2F3 regulates the cardiac cell cycle has been less well studied.
Methods and results: We analyzed gene expression during cell cycle progression by Western blotting and qPCR. We quantified DNA synthesis, mitosis, and cytokinesis by immunocytochemistry. Our data revealed that E2F3 is expressed more in embryonic heart than adult heart. Bioinformatics predicted the 3’UTR of E2F3 contains conserved miR-128 target sites. qPCR revealed that miR-128 was inversely correlated with E2F3 expression in embryonic and adult heart implicating its role in regulation of E2F3 expression. Luciferase assay confirmed miR-128 directly targeted E2F3 and regulated its post-transcription. Knock-down of miR-128 increased E2F3 levels in mouse embryonic cardiomyocytes, whereas its overexpression decreased E2F3 level. Therefore, E2F3 is confirmed as a target of miR-128. Additionally, knock-down of miR-128 increased 5-bromo-2’-deoxy-uridine (Brdu) incorporation and promoted both cytokinesis and mitosis in cardiomyocytes, through activation of Cyclin D1, Cdk4, pRb (807/811) and E2F3 gene expression. In contrast, overexpression of miR-128 produced the opposite effects.
Conclusion: These results identify miR-128 as a critical regulatory gene in controlling cardiomyocyte proliferation. Consequently, miR-128 may be a promising target for innovative regenerative therapy in cardiovascular diseases.
- © 2013 by American Heart Association, Inc.