AUTHOR=Laine Saara , Högel Heidi , Ishizu Tamiko , Toivanen Jussi , Yli-Karjanmaa Minna , Grönroos Tove J. , Rantala Juha , Mäkelä Rami , Hannukainen Jarna C. , Kalliokoski Kari K. , Heinonen Ilkka 

TITLE=Effects of Different Exercise Training Protocols on Gene Expression of Rac1 and PAK1 in Healthy Rat Fast- and Slow-Type Muscles

JOURNAL=Frontiers in Physiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2020.584661

DOI=10.3389/fphys.2020.584661

ISSN=1664-042X

ABSTRACT=<sec><title>Purpose</title><p>Rac1 and its downstream target PAK1 are novel regulators of insulin and exercise-induced glucose uptake in skeletal muscle. However, it is not yet understood how different training intensities affect the expression of these proteins. Therefore, we studied the effects of <italic>high-intensity interval training</italic> (HIIT) and <italic>moderate-intensity continuous training</italic> (MICT) on Rac1 and PAK1 expression in fast-type (<italic>gastrocnemius</italic>, GC) and slow-type (<italic>soleus</italic>, SOL) muscles in rats after HIIT and MICT swimming exercises.</p></sec><sec><title>Methods</title><p>The mRNA expression was determined using qPCR and protein expression levels with reverse-phase protein microarray (RPPA).</p></sec><sec><title>Results</title><p>HIIT significantly <italic>decreased Rac1</italic> mRNA expression in GC compared to MICT (<italic>p</italic> = 0.003) and to the control group (CON) (<italic>p</italic> = 0.001). At the protein level Rac1 was <italic>increased</italic> in GC in both training groups, but only the difference between HIIT and CON was significant (<italic>p</italic> = 0.02). HIIT caused significant <italic>decrease</italic> of <italic>PAK1</italic> mRNA expression in GC compared to MICT (<italic>p</italic> = 0.007) and to CON (<italic>p</italic> = 0.001). At the protein level, HIIT increased PAK1 expression in GC compared to MICT and CON (by ∼17%), but the difference was not statistically significant (<italic>p</italic> = 0.3, <italic>p</italic> = 0.2, respectively). There were no significant differences in the Rac1 or PAK1 expression in SOL between the groups.</p></sec><sec><title>Conclusion</title><p>Our results indicate that HIIT, but not MICT, <italic>decreases</italic> Rac1 and PAK1 mRNA expression and <italic>increases</italic> the protein expression of especially Rac1 but only in fast-type muscle. These exercise training findings may reveal new therapeutic targets to treat patients with metabolic diseases.</p></sec>