Dynamic epigenetic regulation of leptin gene expression during positive and negative energy balance

Project Description:

Leptin is an adipocyte derived hormone that regulates glucose and energy homeostasis by binding to its receptor in the brain. A key function of leptin is to signal the brain the amount of peripheral fat, which in turn leads to centrally mediated adaptation of food intake and energy expenditure. Thus, quantitative changes in leptin expression in relation to the current energy status are crucial for this adipocyte-brain-crosstalk. Human and murine studies have shown that leptin mRNA and plasma concentrations tightly correlate with the number and lipid content of adipocytes. Surprisingly, the precise regulation of leptin gene expression in response to physiologic stimuli is not well studied. Over and under abundance of nutrients are associated with changes in DNA methylation and therefore it is plausible that altered DNA-methylation, triggered by nutrient availability, could quantitatively regulated leptin gene expression. We want to find out if leptin mRNA is regulated by DNA methylation in response to changes in fat mass and environmental stimuli. Furthermore, we want to study if the central leptin-receptor-mediated signaling is part of this epigenetic regulation mechanism.

 

Experimental Methods:

• Working with biopsies from human adipose tissue
• Working with mouse models of obesity and insulin resistance (diet-induced obese mice, ob/ob and db/db mice) and intervention strategies (caloric restriction)
• Phenotyping of mice including measurement of energy expenditure, body composition and body weight
• Protein, DNA and RNA extraction
• PCR, qPCR, Immunoblotting
• Bisulphite-Pyrosequencing for DNA methylation analysis
• Methylation-sensitive luciferase reporter gene assays, electrophoretic mobility shift assays
• Chromatin Immunoprecipitation (ChIP)