Location: Jean Mayer Human Nutrition Research Center On Aging
Project Number: 8050-51000-105-002-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: May 22, 2019
End Date: Sep 30, 2023
Objective 1: To determine the relative role and mechanisms by which ACSL4 expression in white and brown adipocytes modulates adipocyte oxygen consumption, systemic energy expenditure and the development of diet-induced obesity and associated metabolic complications. Sub-objective 1A: To determine how adipocyte ACSL4 expression in response to a high fat diet (HFD) compromises white adipose tissue function and whole-body systemic metabolism. Sub-objective 1B: To determine whether ACSL4, 4-hydroxy-trans-2, 3-nonenal (4-HNE) and/or mitochondrial-derived reactive oxygen species (ROS) play compulsory roles in mediating diet-induced perturbations in gWAT, adipocyte mitochondrial function and cellular bioenergetics. Sub-objective 1C: To determine the role of ACSL4 in promoting HFD-induced brown adipocyte dysfunction and DIO. Objective 2: To determine the role and mechanisms by which interferon related factor 8 (IRF8) adipocyte expression is regulated in diet-induced obesity and modulates the development of diet-induced obesity and associated metabolic complications.
Excessive dietary intake of nutrients above the body’s energetic needs results in obesity and associated metabolic complications. Adipocyte dysfunction, which occurs with increased storage of triacylglycerol in adipocytes, is important in the development of diet-induced obesity (DIO) and associated metabolic complications. Obesity-associated adipocyte dysfunction is associated with features of premature aging such as p53 activation and increased adipose tissue inflammation. In this project plan, we propose to use mouse models to determine the role of specific proteins within adipocytes in the development of obesity and/or associated metabolic complications. Within cells, acyl-CoA synthetases (ACSL) converts fatty acids to fatty acid acyl CoA. Each of the five known ACSL isoforms has been hypothesized to direct acyl-CoAs to specific metabolic rates; we want to determine the role of acyl CoA synthetase 4 (ACSL4) in obesity-associated adipocyte metabolism. In a preliminary study, we investigated and observed that mice with adipocyte deficiency of ACSL4 are protected against DIO, p53 activation, and exhibit increased systemic energy expenditure (EE). In Objective 1 of our project plan we propose to determine the underlying DIO associated mechanisms by which ACSL4 modulates adipocyte and systemic EE and associated metabolic and inflammatory complications. In separate preliminary studies we have discovered that deficiency of interferon related factor 8 (IRF8), specifically within adipocytes of mice, protects against the development of DIO-associated hepatic steatosis and reduced fasting blood glucose. The goals of Objective 2 of this proposal is to elucidate the mechanisms by which adipocyte expression of IRF8 is regulated and the role of adipocyte IRF8 in DIO-associated detrimental alterations in adipose tissue such as adipose tissue inflammation and systemic metabolism.