title: Cyclin-dependent kinase 9 forms a complex with GATA4 and is involved in the differentiation of mouse ES cells into cardiomyocytes.
abstract: The treatment of ES cells with trichostatin A (TSA), an HDAC inhibitor, induces the acetylation of GATA4 as well as histones, and facilitates their differentiation into cardiomyocytes. Recently, we demonstrated that cyclin-dependent kinase 9 (Cdk9), a core component of positive elongation factor-b, is a novel GATA4-binding partner. The present study examined whether Cdk9 forms a complex with GATA4 in mouse ES cells and is involved in their differentiation into cardiomyocytes. Mouse ES cells and Nkx2.5/GFP ES cells, in which green fluorescent protein (GFP) is expressed under the control of the cardiac-specific Nkx2.5 promoter, were induced to differentiate on feeder-free gelatin-coated plates. Immunoprecipitation/Western blotting in nuclear extracts from mouse ES cells demonstrated that Cdk9 as well as cyclin T1 interact with GATA4 during myocardial differentiation. TSA treatment increased Nkx2.5/GFP-positive cells and endogenous mRNA levels of Nkx2.5 and atrial natriuretic factor. To determine the role of Cdk9 in myocardial cell differentiation, we examined the effects of a dominant-negative form of Cdk9 (DN-Cdk9), which loses its kinase activity, and a Cdk9 kinase inhibitor, 5,6-dichloro-1-β-ribofuranosyl-benzimidazole (DRB) on TSA-induced myocardial cell differentiation. The introduction of the DN-Cdk9 inhibited TSA-induced increase in GFP expression in Nkx2.5/GFP ES cells. The administration of DRB into ES cells significantly inhibited TSA-induced increase of endogenous Nkx2.5 mRNA levels in ES cells as well as GFP expression in Nkx2.5/GFP ES cells. These findings demonstrate that Cdk9 is involved in the differentiation of mouse ES cells into cardiomyocytes by interacting with GATA4.
authors.affiliation: Division of Translational Research, Kyoto Medical Center, National Hospital Organization, Fushimi-ku, Kyoto, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Kaichi
authors.forename: Tomohide
authors.initials: T
authors.lastname: Takaya
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Morimoto
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Sunagawa
authors.forename: Teruhisa
authors.initials: T
authors.lastname: Kawamura
authors.forename: Koh
authors.initials: K
authors.lastname: Ono
authors.forename: Akira
authors.initials: A
authors.lastname: Shimatsu
authors.forename: Shiro
authors.initials: S
authors.lastname: Baba
authors.forename: Toshio
authors.initials: T
authors.lastname: Heike
authors.forename: Tatsutoshi
authors.initials: T
authors.lastname: Nakahata
authors.forename: Koji
authors.initials: K
authors.lastname: Hasegawa
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D042863:Cyclin-Dependent Kinase 9 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004004:Dichlororibofuranosylbenzimidazole / Q000494:pharmacology; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000502:physiology*; D050991:GATA4 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006877:Hydroxamic Acids / Q000494:pharmacology; D051379:Mice; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D050991:GATA4 Transcription Factor; C484171:Gata4 protein, mouse; D056572:Histone Deacetylase Inhibitors; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins; D006877:Hydroxamic Acids; C484469:Nkx2-5 protein, mouse; D014157:Transcription Factors; C012589:trichostatin A; D004004:Dichlororibofuranosylbenzimidazole; C467972:Cdk9 protein, mouse; D042863:Cyclin-Dependent Kinase 9