Pronounced expression of the lipolytic inhibitor G0/G1 Switch Gene 2 (G0S2) in adipose tissue from brown bears (Ursus arctos) prior to hibernation.
Prior to hibernation, the brown bear (Ursus arctos) exhibits unparalleled weight gain. Unlike humans, weight gain in bears is associated with lower levels of circulating free fatty acids (FFA) and increased insulin sensitivity. Understanding how free-ranging brown bears suppress lipolysis when gaining weight may therefore provide novel insight toward the development of human therapies. Blood and subcutaneous adipose tissue were collected from immobilized free-ranging brown bears (fitted with GPS-collars) during hibernation in winter and from the same bears during the active period in summer in Dalarna, Sweden. The expression of lipid droplet-associated proteins in adipose tissue was examined under the hypothesis that bears suppress lipolysis during summer while gaining weight by increased expression of negative regulators of lipolysis. Adipose triglyceride lipase (ATGL) expression did not differ between seasons, but in contrast, the expression of ATGL coactivator Comparative gene identification-58 (CGI-58) was lower in summer. In addition, the expression of the negative regulators of lipolysis, G0S2 and cell-death inducing DNA fragmentation factor-a-like effector (CIDE)C markedly increased during summer. Free-ranging brown bears display potent upregulation of inhibitors of lipolysis in adipose tissue during summer. This is a potential mechanism for increased insulin sensitivity during weight gain and G0S2 may serve as a target to modulate insulin sensitivity.
Research Laboratory for Biochemical Pathology, Institute for Clinical Medicine, Aarhus University, Aarhus, Denmark niels.jessen@clin.au.dk.
Niels
N
Jessen
The Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Thomas S
TS
Nielsen
Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark.
Mikkel H
MH
Vendelbo
Research Laboratory for Biochemical Pathology, Institute for Clinical Medicine, Aarhus University, Aarhus, Denmark.
Rikke
R
Viggers
Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, Aas, Norway.
Ole-Gunnar
OG
Støen
Department of Forestry and Wildlife Management, Faculty of Applied Ecology and Agricultural Sciences, Hedmark University College Campus Evenstad, Koppang, Norway.
Alina
A
Evans
Faculty of Health, Department of Cardiology, Örebro University, Örebro, Sweden.
Ole
O
Frøbert
D000222:Adaptation, Physiological / Q000502:physiology*; D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000096:biosynthesis*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006605:Hibernation / Q000502:physiology*; D007333:Insulin Resistance / Q000502:physiology; D008066:Lipolysis / Q000502:physiology*; D008297:Male; D001503:Ursidae
D018797:Cell Cycle Proteins; D005230:Fatty Acids, Nonesterified
Adipose tissue; adipose tissue triglyceride lipase; fatty acid/metabolism; lipolysis