Cardiac-specific transcription in ES cells by Cdk9

Cardiac-specific transcription in ES cells by Cdk9

Shinji Kaichi, Tomohide Takaya, Tatsuya Morimoto, Yoichi Sunagawa, Teruhisa Kawamura, Koh Ono, Koji Hasegawa.

Division of Translational Research, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.

The 25th Annual Meeting of the International Society of Heart Research Japanese Section (Yokohama, Japan), 2008/12/05 (Poster).

Abstract

Histone acetyltransferases (HATs) and histone deacetylases (HDACs) govern gene expression patterns through association with specific transcription factors. Treatment of ES cells with trichostatin A (TSA), and HDAC inhibitor, facilitates their differentiation into cardiac myocytes. We have shown that Cdk9/cyclin T1 complex interacts with one of HATs p300 and a cardiac transcription factor GATA4. To determine the role of Cdk9 in myocardial cell differentiation, we examined effects of Cdk9 kinase inhibitor, 5,6-dichloro-1-β-ribofuranosyl-benzimidazole (DRB) and a dominant-negative form of Cdk9 (DN-Cdk9) on myocardial differentiation. Mouse ES cells and Nkx-2.5/GFP ES cells, in which GFP is expressed under the control of the cardiac-specific Nkx-2.5 promoter, were cultured in monolayer on a flat gelatin-coated plate. TSA induced GFP expression by 6.5-fold in Nkx-2.5/GFP ES cells and endogenous Nkx-2.5 mRNA levels by 16-fold in mouse ES cells. Administration of DRB repressed TSA-induced GFP expression in Nkx-2.5/GFP ES cells by 60% and of endogenous Nkx-2.5 mRNA levels in mouse ES cells by 75%. Finally, introduction of DN-Cdk9 gene into Nkx-2.5/GFP ES cells by lentivirus-mediated gene transfer significantly decreased TSA-induced GFP expression, while introduction of null vector had not effect. These findings demonstrate that Cdk9 is required for the differentiation of mouse ES cells into cardiac myocytes.

Keywords: Cdk9, GATA4, ES cells.