PI:Demitrios Vavvas, M.D.
Abstract:Diabetic retinopathy is a major cause of blindness. Its exact pathophysiology is still unclear.  My laboratory’s long term goal is to elucidate the regulatory mechanisms controlling disease pahthophysiology as a prerequisite to the development of novel and better therapies.  The specific hypothesis behind the proposed research is that AMP dependent kinase (AMPK) is a major regulatory factor controlling progression of diabetic retinopathy.  I am basing this hypothesis on a) the observation that Vascular Endothelial Growth factor (VEGF) has been implicated in diabetic retinopathy progression, b) that AMPK has been shown to be upstream of VEGF in other disease models, and c) that intraocular pharmacologic activation of AMPK leads to vasculopathy.  Based on these observations, the experimental focus of this proposal is on the role of AMPK in diabetic retinopathy.  The specific aims are to:

1.  Define the effects of diabetes mellitus on the expression and activity of different AMPK isoforms in the retina of mice.  I will induce diabetes by streptozotocin and high galactose diet and at various time points after disease initiation I will examine activity of the enzyme by immunoprecipitation and protein levels and localization of AMPK isoforms by Western blots and immunocytochemistry.

2.   Examine the effects of AMPK knockout on diabetic retinopathy progression.  Wild type and AMPK isoform specific knockout mice will be rendered diabetic and diabetic retinopathy progression will be assessed at different time points by examining blood retinal barrier breakdown, white blood cell adhesion and levels of previously established pathologic factors in diabetic retinopathy such as VEGF. 

This proposal is so designed that it can examine both a positive and a negative role of AMPK on diabetic retinopathy progression.


PI:Masao Kineki, M.D., Ph.D.
Abstract:Attenuated insulin secretion and impaired compensatory expansion of pancreatic β-cell
mass are major contributors to hyperglycemia in type 2 diabetes. Nitric oxide (NO) and
inducible NO synthase (iNOS) have been implicated in β-cell dysfunction in diabetes.
Nonetheless, limited knowledge is available about the underlying molecular
pathogenesis. Recently, protein S-nitrosylation, a covalent attachment of NO to cysteine
thiols, has emerged as a major mediator of diverse actions of NO. The preliminary data
showed that: (1) deficiency of S-nitrosoglutathione reductase (GSNOR), a negative
regulator of S-nitrosylation, resulted in hyperglycemia with attenuated insulin secretion
on normal chow, and aggravation of high-fat diet-induced hyperglycemia and β-cell
compensation failure compared with wild-type mice; (2) iNOS inhibitor ameliorated
hyperglycemia with increased plasma insulin level in diabetic db/db-BKS mice; and (3)
GSNOR knockdown decreased glucose-stimulated insulin secretion in cultured β-cells.
Based on previous studies and the solid preliminary data, we wish to test the hypothesis
that GSNOR plays important roles in insulin secretion and protection from obesityinduced β-cell damage. Aim 1 will test the hypothesis that GSNOR deficiency impairs insulin secretion in mice. Aim 2 will determine whether increased expression of GSNOR protects from obesity-induced diabetes in β-cell-specific GSNOR transgenic mice. Aim 3 will determine whether GSNOR deficiency aggravates obesity-induced β-cell damage. This project will identify GSNOR as a novel potential molecular target to prevent and/or reverse β-cell dysfunction in obesity-related diabetes. The proposed studies will provide novel mechanistic insights into β-cell dysfunction to help develop novel preventive and/or therapeutic interventions against type 2 diabetes.