Epigallocatechin-3-gallate (EGCG) is a primary bioactive phytochemical in green tea. Its therapeutic potential in metabolic diseases has been reported; however, the molecular mechanisms of the anti-obesity effect of EGCG have not been fully elucidated. In this study, we examined the effects of EGCG on lipid metabolism and autophagy in adipose tissue. After 8 weeks of high-fat diet feeding, mice were treated with EGCG (20 mg/kg/day) for 2 weeks to test in vivo anti-obesity effects of EGCG. EGCG treatment improved glucose tolerance and caused body weight loss. Interestingly, reduced adipose tissue mass was more prominent in visceral compared to subcutaneous white adipose tissue. Mechanistically, EGCG treatment increased autophagic flux in white adipose tissue through the AMP-activated protein kinase-mediated signaling pathway. Adipocyte-specific knockout of Beclin1 mitigated the effects of EGCG on visceral adipose tissue mass and glucose tolerance, indicating that the anti-obesity effect of EGCG requires Beclin1-dependent autophagy. Collectively, our data demonstrated that EGCG has anti-obesity effects through the upregulation of Beclin1-dependent autophagy and lipid catabolism in white adipose tissue (WAT).
Dysregulation of adipose tissue plasmalogen metabolism is associated with obesity-related metabolic diseases. We report that feeding mice a high-fat diet reduces adipose tissue lysoplasmalogen levels and increases transmembrane protein 86 A (TMEM86A), a putative lysoplasmalogenase. Untargeted lipidomic analysis demonstrates that adipocyte-specific TMEM86A-knockout (AKO) increases lysoplasmalogen content in adipose tissue, including plasmenyl lysophosphatidylethanolamine 18:0 (LPE P-18:0). Surprisingly, TMEM86A AKO increases protein kinase A signalling pathways owing to inhibition of phosphodiesterase 3B and elevation of cyclic adenosine monophosphate. TMEM86A AKO upregulates mitochondrial oxidative metabolism, elevates energy expenditure, and protects mice from metabolic dysfunction induced by high-fat feeding. Importantly, the effects of TMEM86A AKO are largely reproduced in vitro and in vivo by LPE P-18:0 supplementation. LPE P-18:0 levels are significantly lower in adipose tissue of human patients with obesity, suggesting that TMEM86A inhibition or lysoplasmalogen supplementation might be therapeutic approaches for preventing or treating obesity-related metabolic diseases.
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