Abstract

Brown adipose tissue (BAT) activation via cold exposure is increasingly scrutinized as a potential approach to ameliorate cardio-metabolic risk. Transition to cold temperatures requires changes in the partitioning of energy substrates, re-routing fatty acids to BAT to fuel non-shivering thermogenesis. However, the mechanisms behind the redistribution of energy substrates to BAT remain largely unknown. Angiopoietin-like 4 (ANGPTL4), a protein that inhibits lipoprotein lipase (LPL) activity, is highly expressed in BAT. Here, we demonstrate that ANGPTL4 is part of a shuttling mechanism that directs fatty acids derived from circulating triglyceride-rich lipoproteins to BAT during cold. Specifically, we show that cold markedly down-regulates ANGPTL4 in BAT, likely via activation of AMPK, enhancing LPL activity and uptake of plasma triglyceride-derived fatty acids. In contrast, cold up-regulates ANGPTL4 in WAT, abolishing a cold-induced increase in LPL activity. Together, our data indicate that ANGPTL4 is an important regulator of plasma lipid partitioning during sustained cold.

Highlights

  • Adipose tissue can be classified into white adipose tissue (WAT) and brown adipose tissue (BAT)

  • Increased lipoprotein lipase (LPL) activity has been shown to be essential for the lipid-lowering effect of cold exposure, as injection of heparin or tetrahydrolipstatin compromises LPL-dependent uptake of triglyceride-rich lipoproteins (TRLs) and TRL-derived fatty acids (Bartelt et al, 2011)

  • Since Lpl mRNA in Brown adipose tissue (BAT) is only moderately increased upon prolonged cold exposure, it has been suggested that the pronounced increase in LPL activity in BAT occurs at the post-translational level (Giralt et al, 1990; Klingenspor et al, 1996)

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Summary

Introduction

Adipose tissue can be classified into white adipose tissue (WAT) and brown adipose tissue (BAT). Whereas WAT represents the main energy storage organ in the body, BAT is dedicated to the generation of heat via the burning of lipids. BAT is activated during cold exposure, when additional heat production is needed to maintain core body temperature. Heat production by BAT is stimulated via release of norepinephrine by the sympathetic nervous system, causing activation of b-adrenergic signalling and subsequent uncoupling of ATP production from mitochondrial respiration

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