The overall goal of this proposal is to better understand the molecular mechanisms of age-related (3-cell failure and glucose intolerance. Mitochondrial oxidation and phosphorylation activity is reduced by 40% in muscle tissue of older subjects. (3-cell function is also impaired during aging, however, the underlying mechanisms are not completely understood. Mitochondrial networks and morphology are maintained by mitochondria! fusion and fission proteins, though the effects of age and obesity on these proteins in (3-cells have yet to be elucidated. The molecular mechanisms regulating age-related mitochondrial defects in the (3- cell as well as the relationship between mitochondrial morphology and function in this cell type have yet to be elucidated. The proposed research will: [1] define how aging impacts (3-cell mitochondria morphology and function, [2] determine the molecular mechanisms of age-related mitochondrial decline in the (3-cell, [3] determine the impact of obesity on aging p-cell mitochondria. The hypotheses that will be tested are: the process of aging [1] alters mitochondrial morphology and metabolism, [2] causes a decline in p-cell function, and [3] decreases the expression of mitochondrial fusion proteins and biogenesis factors, which are necessary for mitochondrial function. The second set of hypotheses that will be tested are: obesity [1] enhances age-related mitochondrial morphological and functional alterations, [2] causes further decline in (3- cell function, and [3] augments loss of mitochondrial fusion protein and biogenesis factor expression during aging. Experimental techniques include fluorescent confocal and wide field microscopy using autofluorescence, fluorescent dyes, mitochondrially-targeted fluorescent proteins, and FRET-based biosensors, quantitative PCR, immunoblotting, and siRNA targeted to specific mitochondrial proteins in isolated Islets of Langerhans from aging mice. A high-fat diet will be used to induce obesity in these mice and test whether obesity enhances age-related mitochondrial defects in the??-cell. This project will lead to a better understanding of how age and obesity affect insulin secretion and |3-cell health. The results of this work may assist in developing therapies to combat Type 2 diabetes mellitus and age-related decline of insulin secretion.
Older individuals are predisposed to develop diabetes. The mechanisms underlying age dependent diabetes remain unclear, but could involve defects in insulin production and secretion by ?-cells located in the islets of Langerhans of the pancreas. The proposed studies will determine the effects of aging on novel genes that regulate p-cell glucose metabolism and insulin secretion.
