PGC‐1 isoforms and their target genes are expressed differently in human skeletal muscle following resistance and endurance exercise. Issue 10 (5th October 2015) - Silvennoinen, Mika
Abstract: The primary aim of the present study was to investigate the acute gene expression responses of PGC‐1 isoforms and PGC‐1α target genes related to mitochondrial biogenesis ( cytochrome C ), angiogenesis ( VEGF‐A ), and muscle hypertrophy (myostatin), after a resistance or endurance exercise bout. In addition, the study aimed to elucidate whether the expression changes of studied transcripts were linked to phosphorylation of AMPK and MAPK p38. Nineteen physically active men were divided into resistance exercise (RE, n = 11) and endurance exercise (EE, n = 8) groups. RE group performed leg press exercise (10 × 10 RM, 50 min) and EE walked on a treadmill (~80% HRmax, 50 min). Muscle biopsies were obtained from the vastus lateralis muscle before, 30 min, and 180 min after exercise. EE and RE significantly increased the gene expression of alternative promoter originated PGC‐1α exon 1b‐ and 1bxs'‐derived isoforms, whereas the proximal promoter originated exon 1a‐derived transcripts were less inducible and were upregulated only after EE. Truncated PGC‐1α transcripts were upregulated both after EE and RE. Neither RE nor EE affected the expression of PGC‐1β . EE upregulated the expression of cytochrome C and VEGF‐A, whereas RE upregulated VEGF‐A and downregulated myostatin . Both EE and RE increased the levels of p‐AMPK and p‐ MAPK p38, but these changes were not linked to the gene expression responses of PGC‐1 isoforms. The present study comprehensively assayed PGC‐1 transcripts in human skeletal muscle and showed exercise mode‐specific responses thus improving the understanding of early signaling events in exercise‐induced muscle adaptations. Abstract : The study showed that alternative promoter originated PGC‐1α exon 1b‐ and PGC‐1α exon 1b'‐derived transcripts are strongly induced after moderate intensity endurance exercise (EE) and high‐load resistance exercise (RE), whereas the proximal promoter originated PGC‐1α exon 1a‐derived transcripts are less inducible and were upregulated only after EE. Truncated PGC‐1α transcripts were upregulated both after EE and RE, thus there was no clear exercise‐type specificity observed in the responses of these transcripts. EE induced gene expression responses typical for angiogenesis and mitochondrial biogenesis, while RE induced responses typical for angiogenesis and muscle hypertrophy.