Andre, Thomas L

Gann, Joshua J

McKinley, Sarah K

Schwarz, Neil A

Spillane, Mike

Willoughby, Darryn S

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 International Journal of Exercise Science                                                             www.tacsm.org TACSM Abstract   Effect of Resistance Exercise Intensity on the mRNA Expression of PGC-1α Isoforms in Human Skeletal Muscle  Neil A. Schwarz, Sarah K. McKinley, Mike Spillane, Joshua J. Gann, Thomas L. Andre, and Darryn S. Willoughby  Exercise Biochemical Nutrition Laboratory; Department of Health, Human Performance, & Recreation; Baylor University; Waco, TX  Category: Doctoral  Advisor / Mentor: Willoughby, Darryn (darryn_willoughby@baylor.edu)  ABSTRACT Peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) is a co-activator of transcription demonstrated to facilitate beneficial adaptations in skeletal muscle induced by exercise, such as mitochondrial biogenesis and enhanced capillarization.  Recently, novel variants of PGC-1α that result from transcription initiation from an alternative upstream promoter (exon 1b) and alternative splicing of the primary transcript have been identified.  The original PGC-1α isoform transcribed from the canonical promoter has been designated as PGC-1α1, and the novel PGC-1α isoforms have been named PGC-1α2, PGC-1α3, and PGC-1α4.  PGC-1α1, PGC-1a2 and PGC-1a3 have been shown to specifically affect energy metabolism in brown adipose tissue and skeletal muscle; whereas, PGC-1α4 has been implicated to promote skeletal muscle hypertrophy.  The purpose of this study was to describe the mRNA expression of PGC-1α isoforms in response to two resistance exercise intensities.  In a randomized, uniform-balanced, cross-over design, 10 men [23.7 ± 0.9 years old (mean ± SE)] performed two separate lower-body resistance exercise sessions consisting of a lower-intensity protocol (50% of 1-RM) and a higher-intensity (80% of 1-RM) protocol with equal volume loads. Muscle samples were obtained at baseline, 45-min post-exercise (PE), 3-hr PE, 24-hr PE, and 48-hr PE from the vastus lateralis.  From each muscle sample, mRNA expression of PGC-1α1, PGC-1α2, PGC-1α3, and PGC-1α4 was determined using reverse transcriptase-polymerase chain reaction (RT-PCR) and normalized to β-actin.  Two-way repeated-measures ANOVA were performed (p ≤ 0.05) with intensity and time as main effects.  Post-hoc analyses were performed using Fisher's Least Significant Difference (LSD) Test.  Significant main effects existed for time (p < .05), but not intensity (p > .05) for all PGC-1α isoforms.  Additionally, no interaction effects were observed (p > .05).  Post-hoc analyses revealed mRNA expression of PGC-1α1 to be decreased at 24-hr and 48-hr PE.  PGC-1α2 expression increased at 45-min and 3-hr PE before returning to baseline levels at 24-hr PE.  PGC-1α3 expression increased above all other time points at 3-hr PE.  Interestingly, PGC-1α4 mRNA expression decreased at 45-min PE before increasing to peak expression at 3-hr PE.  At 48-hr PE, PGC-1α4 expression returned to below baseline expression similar to expression at 45-min PE.  The results of this study demonstrate PGC-1α transcription to initiate exclusively from the alternative upstream promoter in response to resistance exercise.  Future research is needed to describe the expression of these PGC-1α isoforms at the translational level in order to help elucidate their potential role in human skeletal muscle adaptations to resistance exercise.    International Journal of Exercise Science                                                             www.tacsm.org  

Effect of Resistance Exercise Intensity on the mRNA Expression of PGC-1α Isoforms in Human Skeletal Muscle

http://digitalcommons.wku.edu/cgi/viewcontent.cgi?article=1889&context=ijesab

Effect of Resistance Exercise Intensity on the mRNA Expression of PGC-1α Isoforms in Human Skeletal Muscle

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