Expression of genes involved in lipid metabolism correlate with peroxisome proliferator-activated receptor gamma expression in human skeletal muscle.
Peroxisome proliferator-activated receptor gamma (PPAR-gamma) activation in adipose tissue is known to regulate genes involved in adipocyte differentiation and lipid metabolism. However, the role of PPAR-gamma in muscle remains unclear. To examine the potential regulation of genes by PPAR-gamma in human skeletal muscle, we used semiquantitative RT-PCR to determine the expression of PPAR-gamma, lipoprotein lipase (LPL), muscle carnitine palmitoyl transferase-1 (mCPT1), fatty acid-binding protein (FABP), carnitine acylcarnitine transferase (CACT), and glucose transporter-4 (GLUT4) in freeze-dried muscle samples from 14 male subjects. These samples were dissected free of adipose and other tissue contamination, as confirmed by minimal or absent adipsin expression. Between individuals, the messenger ribonucleic acid concentration of PPAR-gamma varied up to 3-fold, whereas LPL varied up to 6.5-fold, mCPT1 13-fold, FABP 4-fold, CACT 4-fold, and GLUT4 up to 3-fold. The expression of LPL (r2 = 0.54; P = 0.003), mCPT1 (r2 = 0.42; P = 0.012), and FABP (r2 = 0.324; P = 0.034) all correlated significantly with PPAR-gamma expression in the same samples. No significant correlation was observed between the expression of CACT and PPAR-gamma or between GLUT4 and PPAR-gamma. These findings demonstrate a relationship between PPAR-gamma expression and the expression of other genes of lipid metabolism in muscle and support the hypothesis that PPAR-gamma activators such as the antidiabetic thiazolidinediones may regulate fatty acid metabolism in skeletal muscle as well as in adipose tissue.
Lapsys
N M
NM
Metabolism and Diabetes Research Group, The Garvan Institute of Medical Research, Sydney, New South Wales, Australia. n.lapsys@garvan.unsw.edu.au
Kriketos
A D
AD
Lim-Fraser
M
M
Poynten
A M
AM
Lowy
A
A
Furler
S M
SM
Chisholm
D J
DJ
Cooney
G J
GJ
D000368:Aged; D001786:Blood Glucose / Q000378:metabolism; D002333:Carnitine Acyltransferases / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics*; D011416:Complement Factor D; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005786:Gene Expression Regulation; D051275:Glucose Transporter Type 4; D006801:Humans; D007328:Insulin / Q000097:blood; D050356:Lipid Metabolism; D008071:Lipoprotein Lipase / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009004:Monosaccharide Transport Proteins / Q000235:genetics*; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000378:metabolism*; D009363:Neoplasm Proteins; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000502:physiology*; D012016:Reference Values; D012044:Regression Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012697:Serine Endopeptidases / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014280:Triglycerides / Q000097:blood; D025521:Tumor Suppressor Proteins
D001786:Blood Glucose; D002352:Carrier Proteins; C493410:FABP4 protein, human; C107608:FABP7 protein, human; C493411:Fabp4 protein, mouse; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005230:Fatty Acids, Nonesterified; D051275:Glucose Transporter Type 4; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D009363:Neoplasm Proteins; D018160:Receptors, Cytoplasmic and Nuclear; C495692:SLC2A4 protein, human; D014157:Transcription Factors; D014280:Triglycerides; D025521:Tumor Suppressor Proteins; D002333:Carnitine Acyltransferases; D008071:Lipoprotein Lipase; D012697:Serine Endopeptidases; C493488:CFD protein, human; D011416:Complement Factor D; C493491:complement factor D, mouse