Microarray of cardiac biventricle from PGC-1a-/-bf/f/MerCre mice. Mus musculus

The following abstract from the submitted manuscript describes the major findings of this work. The metabolic development of high energy-utilizing organs such as the heart involves mitochondrial proliferation at birth followed by a maturation process during the postnatal period. Conditional gene targeting was used in mice to explore the role of the PPARgamma coactivator 1 (PGC-1) coactivators during postnatal development and in adult heart. Marked mitochondrial derangements were observed in hearts of PGC-1a/b-deficient mice during the postnatal period, including fragmentation and elongation associated with the development of a lethal cardiomyopathy. The expression of multiple genes involved in mitochondrial fusion and fission was downregulated in hearts of PGC-1a/b-deficient mice. PGC-la was shown to activate transcription of the mitofusin 1 (Mfn1) gene by coactivating the estrogen-related receptor a (ERRa) upon a highly conserved element. Surprisingly, PGC-1a/b deficiency did not alter cardiac function or general mitochondrial density and myocyte distribution in adult heart. However, transcriptional profiling and mitochondrial function studies demonstrated that the PGC-1 coactivators are required for full respiratory capacity and high level expression of nuclear- and mitochondrial-encoded genes involved in mitochondrial energy transduction and oxidative phosphorylation pathways in adult heart. These results unveil distinct developmental stage-specific transcriptional programs involved in the maturation and maintenance of mitochondria. Overall design: RNA from five PGC-1a-/- and five PGC-1a-/-bf/f/MerCre mice was analyzed.