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Abstract
As a transcriptional coactivator, PGC-1[alpha] contributes to the regulation of a broad range of metabolic processes in skeletal muscle health and disease; however, there is limited information about the genes it transcriptionally regulates. To identify new potential gene targets of PGC-1[alpha] regulation, mouse C2C12 myotubes were screened by microarray analysis following PGC-1[alpha] overexpression. Genes with an mRNA expression of 2.5-fold or more (P < 0.001) were identified. From these, further genes were singled out if they had no previous connection to PGC-1[alpha] regulation or characterization in skeletal muscle, or were unannotated with no known function. Following confirmation of their regulation by PGC-1[alpha] using qPCR analysis, eight genes were focused on for further investigation (Akr1b10, Rmnd1, 1110008P14Rik, 1700021F05Rik, Mtfp1, Mrm1, Oxnad1 and Cluh). Bioinformatics indicated a number of the genes were linked to a range of metabolic-related functions including fatty acid oxidation, oxido-reductase activity, and mitochondrial remodeling and transport. Treating C2C12 myotubes for 6 h with AICAR, a known activator of AMP kinase and inducer of Pgc-1[alpha] gene expression, increased the mRNA levels of both Pgc-1[alpha] (P < 0.001) and of Mtfp1, Mrm1, Oxnad1 and Cluh (P < 0.05). Screening of the promoter and intron 1 regions also revealed all genes to contain either a consensus or near consensus response elements for the estrogen-related receptor [alpha] (ERR[alpha]), a key transcription factor-binding partner of PGC-1[alpha] in skeletal muscle. Furthermore, knockdown of endogenous ERR[alpha] levels partially or completely blocked the induction of gene expression of all genes by PGC-1[alpha], while each gene was significantly upregulated in the presence of a constitutively active form of ERR[alpha] (P < 0.05) except for Akr1b10. These findings provide preliminary evidence for the novel regulation of these genes by PGC-1[alpha] and its signaling pathway in skeletal muscle.