title: Methionine restriction effects on 11 -HSD1 activity and lipogenic/lipolytic balance in F344 rat adipose tissue.
abstract: Methionine restriction (MR) limits age-related adiposity in Fischer 344 (F344) rats. To assess the mechanism of adiposity resistance, the effect of MR on adipose tissue (AT) 11beta-hydroxysteroid dehydrogenase-1 (11beta-HSD1) was examined. MR induced 11beta-HSD1 activity in all ATs, correlating with increased tissue corticosterone. However, an inverse relationship between 11beta-HSD1 activity and adipocyte size was observed. Because dietary restriction controls lipogenic and lipolytic rates, MR's effects on lipogenic and lipolytic enzymes were evaluated. MR increased adipose triglyceride lipase and acetyl-coenzyme A carboxylase (ACC) protein levels but induced ACC phosphorylation at serine residues that render the enzyme inactive, suggesting alterations of basal lipolysis and lipogenesis. In contrast, no changes in basal or phosphorylated hormone-sensitive lipase levels were observed. ACC-phosphorylated sites were specific for AMP-activated protein kinase (AMPK); therefore, AMPK activation was evaluated. Significant differences in AMPKalpha protein, phosphorylation, and activity levels were observed only in retroperitoneal fat from MR rats. No differences in protein kinase A phosphorylation and intracellular cAMP levels were detected. In vitro studies revealed increased lipid degradation and a trend toward increased lipid synthesis, suggesting the presence of a futile cycle. In conclusion, MR disrupts the lipogenic/lipolytic balance, contributing importantly to adiposity resistance in F344 rats.
authors.affiliation: Orentreich Foundation for the Advancement of Science, Inc., Cold Spring-on-Hudson, NY 10516, USA. perrone@orentreich.org
authors.forename: Carmen E
authors.initials: CE
authors.lastname: Perrone
authors.forename: Dwight A L
authors.initials: DA
authors.lastname: Mattocks
authors.forename: George
authors.initials: G
authors.lastname: Hristopoulos
authors.forename: Jason D
authors.initials: JD
authors.lastname: Plummer
authors.forename: Rozlyn A
authors.initials: RA
authors.lastname: Krajcik
authors.forename: Norman
authors.initials: N
authors.lastname: Orentreich
mesh_terms: D043205:11-beta-Hydroxysteroid Dehydrogenase Type 1 / Q000378:metabolism*; D055372:AMP-Activated Protein Kinases; D000103:Acetyl-CoA Carboxylase / Q000378:metabolism*; D017667:Adipocytes / Q000166:cytology / Q000201:enzymology / Q000378:metabolism; D000273:Adipose Tissue / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D050356:Lipid Metabolism; D050155:Lipogenesis; D008066:Lipolysis; D008715:Methionine / Q000172:deficiency*; D009097:Multienzyme Complexes / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D009097:Multienzyme Complexes; D008715:Methionine; D000242:Cyclic AMP; D043205:11-beta-Hydroxysteroid Dehydrogenase Type 1; D017346:Protein Serine-Threonine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D055372:AMP-Activated Protein Kinases; D000103:Acetyl-CoA Carboxylase