title: Endurance training-induced accumulation of muscle triglycerides is coupled to upregulation of stearoyl-CoA desaturase 1.
abstract: Stearoyl-CoA desaturase (SCD), a rate-limiting enzyme in the biosynthesis of monounsaturated fatty acids, has recently been shown to be a critical control point in regulation of liver and skeletal muscle metabolism. Herein, we demonstrate that endurance training significantly increases both SCD1 mRNA and protein levels in the soleus muscle, whereas it does not affect SCD1 expression in the EDL muscle and liver. Desaturation index (18:1Δ9/18:0 ratio), an indirect indicator of SCD1 activity, was also significantly higher (3.6-fold) in soleus of trained rats compared with untrained animals. Consistent with greater SCD1 expression/activity, the contents of free fatty acids, diacylglycerol, and triglyceride were elevated in soleus of trained rats. However, training did not affect lipid concentration in EDL and liver. Additionally, endurance training activated the AMP-activated protein kinase pathway as well as increased peroxisome proliferator-activated receptor (PPAR)-δ and PPARα gene expression and activity in soleus and liver. Increased lipid accumulation in soleus was coupled with elevated protein levels of fatty acid synthase, mRNA levels of diacylglycerol acyltransferase and glycerol-3-phosphate transferase, as well as increased levels of proteins involved in fatty acid transport (fatty acid translocase/CD36, fatty acid transport protein 1). Interestingly, sterol regulatory element-binding protein (SREBP)-1c expression and SREBP-1 protein levels were not affected by exercise training. Together, the obtained data suggest that SCD1 upregulation plays an important role in adaptation of oxidative muscle to endurance training.
authors.affiliation: Laboratory of Cell Signaling and Metabolic Disorders, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland. adobrzyn@nencki.gov.pl
authors.forename: Pawel
authors.initials: P
authors.lastname: Dobrzyn
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Pyrkowska
authors.forename: Magdalena
authors.initials: M
authors.lastname: Jazurek
authors.forename: Konrad
authors.initials: K
authors.lastname: Szymanski
authors.forename: Jozef
authors.initials: J
authors.lastname: Langfort
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Dobrzyn
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000103:Acetyl-CoA Carboxylase / Q000378:metabolism; D000222:Adaptation, Physiological; D000818:Animals; D001692:Biological Transport; D005227:Fatty Acids / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D050356:Lipid Metabolism / Q000235:genetics; D008099:Liver / Q000378:metabolism; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000201:enzymology*; D010084:Oxidation-Reduction; D047494:PPAR delta / Q000378:metabolism; D047495:PPAR gamma / Q000378:metabolism; D010766:Phosphorylation; D010807:Physical Endurance; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013230:Stearoyl-CoA Desaturase / Q000235:genetics / Q000378:metabolism*; D014280:Triglycerides / Q000378:metabolism*; D015854:Up-Regulation; D019014:fas Receptor / Q000378:metabolism
chemical_list: C491898:Fas protein, rat; D005227:Fatty Acids; D047494:PPAR delta; D047495:PPAR gamma; D012333:RNA, Messenger; D014280:Triglycerides; D019014:fas Receptor; D013230:Stearoyl-CoA Desaturase; D055372:AMP-Activated Protein Kinases; D000103:Acetyl-CoA Carboxylase