The effect of Tbx6 on the mouse heart

The Mammalian cardiomyocyte (CM) cell cycle is tightly regulated by a complex network of transcription factors; however, the gene regulatory networks depending on their developmental stages are unclear. Here, we report that Tbx6, expressed in the cardiac mesoderm, promote cell cycle re-entry in vitro and in vivo. We performed a gain of function screening for cardiac development regulator genes that promoted neonatal CM proliferation. Tbx6 activate the cell cycle and promote cultured neonatal CM proliferation. Next, we generated recombinant adeno-associated virus serotype 9 vector encoding Tbx6 (AAV9-Tbx6). Injection of AAV9-Tbx6 was shown to promote cell cycle re-entry of CMs in both postnatal and adult mice. Tbx6 overexpression activated cell cycle activators, while repressed cell cycle inhibitor gene. Thus, Tbx6 promotes neonatal CM proliferation in vitro and adult CM cell cycle re-entry in vivo. We analyzed gene expression levels in heart that is introduced into PBS or Tbx6 at birth and scarify after 7 days or 30 days by microarray (Clariom S Array, Mouse, Affymetrix) according to the manufacturer’s instructions. Prior to analysis, all data were normalized by using a Single Space Transformation and Robust Multichip Analysis (SST-RMA) algorithm with Affymetrix Expression Console software version1.4.