Joerg Heeren1, Ludger Scheja. 1. Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Abstract
PURPOSE OF REVIEW: This article explores how the interplay between lipid metabolism and thermogenic adipose tissues enables proper physiological adaptation to cold environments in rodents and humans. RECENT FINDINGS: Cold exposure triggers systemic changes in lipid metabolism, which increases fatty acid delivery to brown adipose tissue (BAT) by various routes. Next to fatty acids generated intracellularly by de-novo lipogenesis or by lipolysis at lipid droplets, brown adipocytes utilize fatty acids released by white adipose tissue (WAT) for adaptive thermogenesis. WAT-derived fatty acids are internalized directly by BAT, or indirectly after hepatic conversion to very low-density lipoproteins and acylcarnitines. In the postprandial state, chylomicrons hydrolyzed by lipoprotein lipase - activated specifically in thermogenic adipocytes - are the predominant fatty acid source. Cholesterol-enriched chylomicron remnants and HDL generated by intravascular lipolysis in BAT are cleared more rapidly by the liver, explaining the antiatherogenic effects of BAT activation. Notably, increased cholesterol flux and elevated hepatic synthesis of bile acids under cold exposure further promote BAT-dependent thermogenesis. SUMMARY: Although pathways providing fatty acids for activated BAT have been identified, more research is needed to understand the integration of lipid metabolism in BAT, WAT and liver, and to determine the relevance of BAT for human energy metabolism.
PURPOSE OF REVIEW: This article explores how the interplay between lipid metabolism and thermogenic adipose tissues enables proper physiological adaptation to cold environments in rodents and humans. RECENT FINDINGS: Cold exposure triggers systemic changes in lipid metabolism, which increases fatty acid delivery to brown adipose tissue (BAT) by various routes. Next to fatty acids generated intracellularly by de-novo lipogenesis or by lipolysis at lipid droplets, brown adipocytes utilize fatty acids released by white adipose tissue (WAT) for adaptive thermogenesis. WAT-derived fatty acids are internalized directly by BAT, or indirectly after hepatic conversion to very low-density lipoproteins and acylcarnitines. In the postprandial state, chylomicrons hydrolyzed by lipoprotein lipase - activated specifically in thermogenic adipocytes - are the predominant fatty acid source. Cholesterol-enriched chylomicron remnants and HDL generated by intravascular lipolysis in BAT are cleared more rapidly by the liver, explaining the antiatherogenic effects of BAT activation. Notably, increased cholesterol flux and elevated hepatic synthesis of bile acids under cold exposure further promote BAT-dependent thermogenesis. SUMMARY: Although pathways providing fatty acids for activated BAT have been identified, more research is needed to understand the integration of lipid metabolism in BAT, WAT and liver, and to determine the relevance of BAT for human energy metabolism.
Authors: Alexander W Fischer; Kirstin Albers; Christian Schlein; Frederike Sass; Lucia M Krott; Hartwig Schmale; Philip L S M Gordts; Ludger Scheja; Joerg Heeren Journal: Biochim Biophys Acta Mol Basis Dis Date: 2019-03-21 Impact factor: 5.187
Authors: Hana Malinská; Martina Hüttl; Denisa Miklánková; Jaroslava Trnovská; Iveta Zapletalová; Martin Poruba; Irena Marková Journal: Int J Mol Sci Date: 2021-04-26 Impact factor: 5.923
Authors: Gernot F Grabner; Nermeen Fawzy; Renate Schreiber; Lisa M Pusch; Dominik Bulfon; Harald Koefeler; Thomas O Eichmann; Achim Lass; Martina Schweiger; Gunther Marsche; Gabriele Schoiswohl; Ulrike Taschler; Robert Zimmermann Journal: J Lipid Res Date: 2020-04-29 Impact factor: 5.922