Age-related differences in messenger ribonucleic acid expression of key proteins involved in adipose cell differentiation and metabolism.
This study was performed to compare the expression of key proteins [lipoprotein lipase (LPL), hormone-sensitive lipase (HSL), complement 3 (C3), and peroxisome proliferator-stimulated receptor-gamma (PPAR gamma)] involved in sc abdominal adipose tissue (AT) metabolism of young (n = 13) vs. middle-aged (n = 16) men. The sc abdominal AT-LPL activity as well as fat cell lipolysis were also measured in both groups of men. Young and middle-aged men displayed similar body weight and sc abdominal fat accumulation, measured by computed tomography. However, middle-aged men were characterized by a higher percent body fat (28 +/- 5% vs. 22 +/- 7%; P < 0.05) than young subjects. No difference between groups was observed in sc abdominal adipose tissue LPL activity. On the other hand, maximal lipolytic responses of sc abdominal adipocytes to isoproterenol (beta-adrenergic agonist) or to postadrenoceptor agents such as dibutyryl cAMP, forskolin, and theophylline were lower in middle-aged than in young men (P < 0.05). AT-LPL messenger ribonucleic acid (mRNA) levels were similar regardless of the subject's age. However, HSL, C3, and PPAR gamma mRNA levels were higher in middle-aged than in young individuals (P < 0.01-0.05). After correction for percent body fat, only HSL and C3 mRNA levels remained significantly different between groups (P < 0.05). Taken together, these results suggest that aging has an effect on the up-regulation of HSL and C3 mRNA levels, whereas PPAR gamma expression seems to be related mainly to increased adiposity.
Imbeault
P
P
Physical Activity Sciences Laboratory, Department of Social and Preventive Medicine, Laval University, Ste-Foy, Québec, Canada G1K 7P4.
Vidal
H
H
Tremblay
A
A
Vega
N
N
Nadeau
A
A
Després
J P
JP
Mauriège
P
P
D000005:Abdomen; D017667:Adipocytes / Q000187:drug effects / Q000502:physiology; D000273:Adipose Tissue / Q000166:cytology* / Q000254:growth & development / Q000502:physiology*; D000328:Adult; D000375:Aging / Q000502:physiology*; D003994:Bucladesine / Q000494:pharmacology; D002170:Canada; D002454:Cell Differentiation; D005576:Colforsin / Q000494:pharmacology; D003176:Complement C3 / Q000235:genetics; D005602:France; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D008066:Lipolysis / Q000187:drug effects; D008071:Lipoprotein Lipase / Q000235:genetics; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000235:genetics*; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics; D002787:Sterol Esterase / Q000235:genetics; D013806:Theophylline / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic; D044465:White People
D003176:Complement C3; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; D005576:Colforsin; D003994:Bucladesine; D013806:Theophylline; D002787:Sterol Esterase; D008071:Lipoprotein Lipase; D007545:Isoproterenol