Cardiac-specific deletion of mnage--trois-1 (MAT1)

The Cdk7/cyclin H/mnage--trois 1 (MAT1) heterotrimer has proposed functions in transcription as the kinase component of basal transcription factor TFIIH and is activated in adult hearts by hypertrophic pathways. Using cardiac-specific Cre, we ablated MAT1 in myocardium. Despite reduced Cdk7 activity, MAT1-deficient hearts grew normally. However, fatal heart failure ensued at 6-8 weeks. By microarray profiling, quantitative RT-PCR, and Western blotting at 4 weeks, genes for energy metabolism were found to be suppressed selectively, including targets of peroxisome proliferator-activated receptor-gamma coactivator-1 (PGC-1). Cardiac metabolic defects were substantiated in isolated perfused hearts and isolated mitochondria. In culture, deleting MAT1 with Cre disrupted PGC-1 function: PGC-1 failed to activate PGC-1-responsive promoters and nuclear receptors, GAL4-PGC-1 was functionally defective, and PGC-1 likewise was deficient. PGC-1 was shown to interact with MAT1 and Cdk7, in co-precipitation assays. Thus, we demonstrate an unforeseen essential role for MAT1 in operation of the PGC-1 family of co-activators.

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Sano M, Izumi Y, Helenius K, Asakura M, Rossi DJ, Xie M, Taffet G, Hu L, Pautler RG, Wilson CR, Boudina S, Abel ED, Taegtmeyer H, Scaglia F, Graham BH, Kralli A, Shimizu N, Tanaka H, Mäkelä TP, Schneider MD