Novel Regulators of Glucose Homeostasis in Aging

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Biological changes associated with aging are a major risk for increased incidence of many age-related diseases including insulin resistance/type 2 diabetes mellitus, Alzheimer's disease (AD), stroke and ischemic heart disease. The focus of our research has been to identify biological factors that change with age and may be involved in the etiology or pathogenesis of age-related diseases. A novel mitochondrial peptide, Humanin (HN), has been recognized for its cyto-protective role due to its anti-apoptotic function in many tissues, especially AD related insults. In addition, HN is closely linked to the IGF system, which is recognized for its role in aging. In our preliminary data we show that that HN levels in tissues and secretions decrease with age. We also show that HN significantly improves overall insulin sensitivity both at the liver and skeletal muscle in young rats. Furthermore, molecular manipulations of HN create potent humanin analogs (that interact with IGF-1 system) that can reproduce the effects of native endogenous HN. Based on our preliminary data, we hypothesize that the decrease in HN levels increase risk of insulin resistance and diabetes in aging rodents, and this effect is mediated through the hypothalamus. Furthermore, we hypothesize that administration of HN to aging rodents will substantially alter the risk of diabetes. Using state of the art technology, we propose to evaluate the role of HN in the integral features that leads to the impaired glucose metabolism in aging: a) diminished ability of insulin to restrain the production of glucose from the liver (or hepatic glucose production) and/or to promote the disposal of glucose in peripheral tissues, in part by a central mechanism, and b) increase in fat especially visceral fat. UN represents a novel molecular link between impaired carbohydrate metabolism, diabetes and neuro-degeneration, and may provide not only mechanistic explanations but also potential therapeutic options in this common clinical constellation affecting millions of people.