Diabetic retinopathy is the leading cause of blindness in working age Americans, accounting for more than 12,000 new cases in the United States each year. The principle evidenced based treatment for proliferative diabetic retinopathy involves laser-mediated ablation, which fails to alter the molecular pathology of the disease, and as such, nearly half of patients require future treatments. Thus, our overall goal is to identify new targets for intervention at the molecular level that will lead to development of innovative, nondestructive therapies that address treatment of the cause of diabetic retinopathy, rather than the effect. The pathogenesis of this disease is caused by a combination of hyperglycemia and a reduction in insulin mediated signaling, which results in diabetic neurovascular complications through the induction of structural and physiological changes in the retina. The research proposed in this application is innovative, because it represents an entirely different approach to address the molecular basis of diabetic retinopathy, i.e. hyperglycemia-induced alterations in the translational control of gene expression. The central hypothesis is that the addition of O- linked N-Acetylglucosamine (O-GlcNAcylation) to serine or threonine residues of translation initiation factors mediates a shift from cap-dependent to cap-independent mRNA translation, resulting in an altered gene expression pattern that contributes to the pathophysiology of diabetic retinopathy. The hypothesis is supported by findings of elevated flux of glucose through the hexosamine biosynthetic pathway and O-GlcNAcylation of key components of the mRNA cap-binding complex, including eIF4E binding protein 1, eIF4G, eIF4A, and poly(A)-binding protein, under conditions of diabetes-induced hyperglycemia. Furthermore, herein we provide preliminary evidence that hyperglycemia favors the translation of mRNAs with internal ribosome entry sites, such as those encoding key vascular growth factors, in a manner that is dependent on the disruption of eIF4F complex assembly. During the mentored phase, the PI will acquire technical expertise from the laboratory of Dr. Gerald Hart on the methodology used to identify O-GlcNAcylation sites in proteins that control mRNA translation. Once the modified sites have been identified, the mechanisms through which hyperglycemia impairs eIF4F complex assembly will be defined. The mentored phase will also provide time for the candidate to receive guidance from Dr. Thomas Gardner to evaluate if preventing disruption of eIF4F complex assembly is sufficient to inhibit early preclinical phases of the pathogenesis of this disease in a mouse model of diabetes. With respect to outcomes, this project is expected to not only expand the PI's skills and systems of analysis, but will also identify novel mechanisms that link the metabolic abnormalities associated with diabetes to enhanced vascular growth factor expression in the retina. Identification of such mechanisms is significant because it is expected to validate new targets for the development of preventive and/or therapeutic interventions aimed at addressing the molecular basis of diabetic retinopathy and promoting healthy vision.

Public Health Relevance

Current treatments for diabetic retinopathy that fully address its molecular pathogenesis are presently lacking. The present application will identify novel mechanisms that regulate the hyperglycemia-induced expression of angiogenic factors in the retina. These findings are expected to provide new targets for intervention at the level of gene expression that will lead to the development of innovative therapies that target the leading cause of blindness among middle-age individuals.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Transition Award (R00)
Project #
4R00EY023612-03
Application #
9057160
Study Section
Special Emphasis Panel (NSS)
Program Officer
Shen, Grace L
Project Start
2015-08-01
Project End
2018-07-31
Budget Start
2015-08-01
Budget End
2016-07-31
Support Year
3
Fiscal Year
2015
Total Cost
Indirect Cost
Name
Pennsylvania State University
Department
Physiology
Type
Schools of Medicine
DUNS #
129348186
City
Hershey
State
PA
Country
United States
Zip Code
17033
Dai, Weiwei; Dierschke, Sadie K; Toro, Allyson L et al. (2018) Consumption of a high fat diet promotes protein O-GlcNAcylation in mouse retina via NR4A1-dependent GFAT2 expression. Biochim Biophys Acta Mol Basis Dis 1864:3568-3576
Dai, Weiwei; Miller, William P; Toro, Allyson L et al. (2018) Deletion of the stress-response protein REDD1 promotes ceramide-induced retinal cell death and JNK activation. FASEB J :fj201800413RR
Miller, William P; Yang, Chen; Mihailescu, Maria L et al. (2018) Deletion of the Akt/mTORC1 Repressor REDD1 Prevents Visual Dysfunction in a Rodent Model of Type 1 Diabetes. Diabetes 67:110-119
Miller, William P; Ravi, Suhana; Martin, Tony D et al. (2017) Activation of the Stress Response Kinase JNK (c-Jun N-terminal Kinase) Attenuates Insulin Action in Retina through a p70S6K1-dependent Mechanism. J Biol Chem 292:1591-1602
Black, Adam J; Gordon, Bradley S; Dennis, Michael D et al. (2016) Regulation of protein and mRNA expression of the mTORC1 repressor REDD1 in response to leucine and serum. Biochem Biophys Rep 8:296-301
Kimball, Scot R; Gordon, Bradley S; Moyer, Jenna E et al. (2016) Leucine induced dephosphorylation of Sestrin2 promotes mTORC1 activation. Cell Signal 28:896-906
Moore, Joshua A; Miller, William P; Dennis, Michael D (2016) Glucosamine induces REDD1 to suppress insulin action in retinal Müller cells. Cell Signal 28:384-390
Miller, William P; Mihailescu, Maria L; Yang, Chen et al. (2016) The Translational Repressor 4E-BP1 Contributes to Diabetes-Induced Visual Dysfunction. Invest Ophthalmol Vis Sci 57:1327-37
Dennis, Michael D; Kimball, Scot R; Fort, Patrice E et al. (2015) Regulated in development and DNA damage 1 is necessary for hyperglycemia-induced vascular endothelial growth factor expression in the retina of diabetic rodents. J Biol Chem 290:3865-74
Kimball, Scot R; Ravi, Suhana; Gordon, Bradley S et al. (2015) Amino Acid-Induced Activation of mTORC1 in Rat Liver Is Attenuated by Short-Term Consumption of a High-Fat Diet. J Nutr 145:2496-502

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