The Muday Laboratory, Wake Forest University

Molecular mechanisms of sexual dimorphism
in leptin synthesis and signaling

Leptin, an adipokine that is secreted by adipocytes, regulates lipid metabolism and controls eating behavior.  In most mammals, this hormone is at significantly higher levels in females.  We are exploring the molecular mechanisms that lead to this sexual dimorphism and how aging and changing estrogen levels affect leptin levels.  We are examining the expression of leptin and its receptors in cell culture cells in response to treatment with estrogen.  We are examining expression at the level of mRNA encoding these proteins, using reverse transcriptase-polymerase chain reaction (RT-PCR) in collaboration with Dr. Erik Johnson, of the Biology Department.  We are also examining the accumulation of leptin and leptin receptor iso-forms using a range of immunological techniques in collaboration with Dr. Carole Browne, also of the Biology Department.  We will also extend these studies to understand the signaling pathways that lead to sexual dimorphism in leptin synthesis and signaling.

Impact of obesity hormones on weight and osteoarthritis in older women 

Leptin is a peptide hormone and member of the cytokine family—the same family of molecules that regulate inflammation and the immune response. Studies have reported increased leptin levels in correlation with the degree of inflammation in autoimmune diseases including rheumatoid and osteo-arthritis.  Weight loss has been shown to separately decrease leptin and decrease symptoms of knee arthritis. In collaboration with Dr. Gary Miller, in the department of Health and Exercise Science, we are looking at the levels of leptin, in a population of older women to ask if there is a relationship between inflammation, obesity, and leptin levels.  We are also examining the levels of adiponection, a hormone usually produced at high levels in lean individuals, as well as the levels of leptin receptors.  The goal of this study will be to try to dissect the role of leptin in regulation of inflammation and metabolism. 

(graduate students in bold face type)

Miller GD, Jenks MZ, Vendela M, Norris JL, Muday GK (2012) Influence of weight loss, body composition, and lifestyle behaviors on plasma adipokines: a randomized weight loss trial in older men and women with symptomatic knee osteoarthritis. J Obes. 2012;2012:708505. doi: 10.1155/2012/708505. Epub 2012 Dec 26.

Jenks, MZ, Fairfield, H, Miller, G, and Muday, GK (2010) Regulation of Leptin Synthesis By Sex Steroid Hormones. Obesity, 18:S59-S60.

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