Oral Presentation 26th Annual Lorne Proteomics Symposium 2021

Proteomic analysis of adipose depots after intermittent fasting reveals visceral fat preservation mechanisms (#20)

Dylan J Harney 1 , Michelle Cielesh 1 , Renee Chu 1 , Kristen C Cooke 1 , David E James 1 , Jacqueline Stöckli 1 , Mark Larance 1
  1. School of Life and Environmental Sciences, University of Sydney, Camperdown, NSW, Australia

Intermittent fasting (IF) is a beneficial diet that improves metabolic health independent of weight loss. Adipose tissue plays a key role in the fasting response, mobilising fatty acid reserves for use by other tissues such as the liver. There are many different adipose tissue depots around the body and each is known to have a distinct physiological response to fasting. But the proteomic response of each distinct adipose depot is currently poorly defined. Here, we explore the response of three key adipose depots, visceral white adipose tissue (vWAT), subcutaneous white adipose tissue (scWAT) and brown adipose tissue (BAT), to every-other-day fasting (EODF) in mice using proteomics. A key change in both vWAT and scWAT was increased mitochondrial protein content associated with browning after EODF. These included metabolic enzymes crucial to pyruvate metabolism and the citric acid cycle as well as upstream cytosolic enzymes involved in glycolysis. These effects were correlated with increased fatty acid synthesis enzymes, such as the ACC1 protein complex, in both WAT depots, but not brown adipose tissue. UCP1 was differently regulated by EODF where it was increased in scWAT but not vWAT even although both had significant mitochondrial accumulation after EODF. Strikingly, EODF treatment downregulated lipolysis specifically in vWAT, mediated by a large decrease in the protein abundance of the catecholamine receptor (ADRB3). This decrease resulted in reduced intracellular lipolytic signalling, which lead to reduced free fatty acid release when challenged with an overnight fast and reduced sensitivity to lipolysis-inducing drugs. Together these changes would be important for the preservation of the visceral lipid store during EODF. Enrichment analysis also revealed downregulation of inflammatory collagen IV specifically in vWAT, which may contribute to the improved insulin sensitivity phenotype in these animals. Further analysis demonstrated decreased abundance of macrophage-specific and eosinophil-specific protein markers that could lead to a further reduction in adipose tissue inflammation. This resource is provided as a web-based interactive visualisation (larancelab.com/fat-eodf) for adipose depot-specific fasting adaptations in mice.