title: The consequences of acute cold exposure on protein oxidation and proteasome activity in short-tailed field voles, microtus agrestis.
abstract: During cold exposure, animals upregulate their metabolism and food intake, potentially exposing them to elevated reactive oxygen species (ROS) production and oxidative damage. We investigated whether acute cold (7 +/- 3 degrees C) exposure (1, 10, or 100 h duration) affected protein oxidation and proteasome activity, when compared to warm controls (22 +/- 3 degrees C), in a small mammal model, the short-tailed field vole Microtus agrestis. Protein carbonyls and the chymotrypsin-like proteasome activity were measured in plasma, heart, liver, kidney, small intestine (duodenum), skeletal muscle (gastrocnemius), and brown adipose tissue (BAT). Trypsin-like and peptidyl-glutamyl-like proteasome activities were determined in BAT, liver, and skeletal muscle. Resting metabolic rate increased significantly with duration of cold exposure. In skeletal muscle (SM) and liver, protein carbonyl levels also increased with duration of cold exposure, but this pattern was not repeated in BAT where protein carbonyls were not significantly elevated. Chymotrpsin-like proteasome activity did not differ significantly in any tissue. However, trypsin-like activity in SM and peptidyl-glutamyl-like activity in both skeletal muscle and liver, were reduced during the early phase of cold exposure (1-10 h), correlated with the increased carbonyl levels in these tissues. In contrast there was no reduction in proteasome activity in BAT during the early phase of cold exposure and peptidyl-glutamyl-like activity was significantly increased, correlated with the lack of accumulation of protein carbonyls in this tissue. The upregulation of proteasome activity in BAT may protect this tissue from accumulated oxidative damage to proteins. This protection may be a very important factor in sustaining uncoupled respiration, which underpins nonshivering thermogenesis at cold temperatures.
authors.affiliation: Aberdeen Centre for Energy Expenditure and Obesity (ACERO), Department of Zoology, Aberdeen University, UK.
authors.forename: Colin
authors.initials: C
authors.lastname: Selman
authors.forename: Tilman
authors.initials: T
authors.lastname: Grune
authors.forename: Alexandra
authors.initials: A
authors.lastname: Stolzing
authors.forename: Manuela
authors.initials: M
authors.lastname: Jakstadt
authors.forename: Jane S
authors.initials: JS
authors.lastname: McLaren
authors.forename: John R
authors.initials: JR
authors.lastname: Speakman
mesh_terms: D002001:Adipose Tissue, Brown / Q000378:metabolism; D000818:Animals; D003411:Arvicolinae / Q000378:metabolism*; D001481:Basal Metabolism; D001833:Body Temperature Regulation; D002918:Chymotrypsin / Q000378:metabolism; D003080:Cold Temperature; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D046988:Proteasome Endopeptidase Complex; D011506:Proteins / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D009097:Multienzyme Complexes; D011506:Proteins; D017382:Reactive Oxygen Species; D002918:Chymotrypsin; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex