REDD1 activates a ROS-generating feedback loop in the retina of diabetic mice

William P. Miller, Allyson L. Toro, Alistair Barber, Michael Dennis

Research output: Contribution to journalArticle

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Abstract

PURPOSE. The present study was designed to evaluate the role of the stress response protein REDD1 in diabetes-induced oxidative stress and retinal pathology. METHODS. Wild-type and REDD1-deficient mice were administered streptozotocin to induce diabetes. Some mice received the antioxidant N-acetyl-l-cysteine (NAC). Visual function was assessed by virtual optometry. Retinas were analyzed by Western blotting. Reactive oxygen species (ROS) were assessed by 2,7-dichlorofluoroscein. Similar analyses were performed on R28 retinal cells in culture exposed to hyperglycemic conditions, NAC, and/or the exogenous ROS source hydrogen peroxide. RESULTS. In the retina of diabetic mice, REDD1 expression and ROS were increased. In cells in culture, hyperglycemic conditions enhanced REDD1 expression, ROS levels, and the mitochondrial membrane potential. However, similar effects were not observed in the retina of diabetic mice or cells lacking REDD1. In the retina of diabetic mice and cells exposed to hyperglycemic conditions, NAC normalized ROS and prevented an increase in REDD1 expression. Diabetic mice receiving NAC also exhibited improved contrast sensitivity as compared to diabetic controls. Hydrogen peroxide addition to culture medium increased REDD1 expression and attenuated Akt/GSK3 phosphorylation in a REDD1-dependent manner. In REDD1-deficient cells exposed to hyperglycemic conditions, expression of a dominant negative Akt or constitutively active GSK3 increased the mitochondrial membrane potential and promoted ROS. CONCLUSIONS. The findings provide new insight into the mechanism whereby diabetes-induced hyperglycemia causes oxidative stress and visual dysfunction. Specifically, hyperglycemiainduced REDD1 activates a ROS-generating feedback loop that includes Akt/GSK3. Thus, therapeutic approaches targeting REDD1 expression and ROS may be beneficial for preventing diabetes-induced visual dysfunction.

Original languageEnglish (US)
Pages (from-to)2369-2379
Number of pages11
JournalInvestigative Ophthalmology and Visual Science
Volume60
Issue number6
DOIs
StatePublished - May 1 2019

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Retina
Reactive Oxygen Species
Cysteine
Mitochondrial Membrane Potential
Hydrogen Peroxide
Oxidative Stress
Cell Culture Techniques
Optometry
Contrast Sensitivity
Streptozocin
Heat-Shock Proteins
Hyperglycemia
Culture Media
Antioxidants
Western Blotting
Phosphorylation
Pathology

All Science Journal Classification (ASJC) codes

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

Cite this

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title = "REDD1 activates a ROS-generating feedback loop in the retina of diabetic mice",
abstract = "PURPOSE. The present study was designed to evaluate the role of the stress response protein REDD1 in diabetes-induced oxidative stress and retinal pathology. METHODS. Wild-type and REDD1-deficient mice were administered streptozotocin to induce diabetes. Some mice received the antioxidant N-acetyl-l-cysteine (NAC). Visual function was assessed by virtual optometry. Retinas were analyzed by Western blotting. Reactive oxygen species (ROS) were assessed by 2,7-dichlorofluoroscein. Similar analyses were performed on R28 retinal cells in culture exposed to hyperglycemic conditions, NAC, and/or the exogenous ROS source hydrogen peroxide. RESULTS. In the retina of diabetic mice, REDD1 expression and ROS were increased. In cells in culture, hyperglycemic conditions enhanced REDD1 expression, ROS levels, and the mitochondrial membrane potential. However, similar effects were not observed in the retina of diabetic mice or cells lacking REDD1. In the retina of diabetic mice and cells exposed to hyperglycemic conditions, NAC normalized ROS and prevented an increase in REDD1 expression. Diabetic mice receiving NAC also exhibited improved contrast sensitivity as compared to diabetic controls. Hydrogen peroxide addition to culture medium increased REDD1 expression and attenuated Akt/GSK3 phosphorylation in a REDD1-dependent manner. In REDD1-deficient cells exposed to hyperglycemic conditions, expression of a dominant negative Akt or constitutively active GSK3 increased the mitochondrial membrane potential and promoted ROS. CONCLUSIONS. The findings provide new insight into the mechanism whereby diabetes-induced hyperglycemia causes oxidative stress and visual dysfunction. Specifically, hyperglycemiainduced REDD1 activates a ROS-generating feedback loop that includes Akt/GSK3. Thus, therapeutic approaches targeting REDD1 expression and ROS may be beneficial for preventing diabetes-induced visual dysfunction.",
author = "Miller, {William P.} and Toro, {Allyson L.} and Alistair Barber and Michael Dennis",
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REDD1 activates a ROS-generating feedback loop in the retina of diabetic mice. / Miller, William P.; Toro, Allyson L.; Barber, Alistair; Dennis, Michael.

In: Investigative Ophthalmology and Visual Science, Vol. 60, No. 6, 01.05.2019, p. 2369-2379.

Research output: Contribution to journalArticle

TY - JOUR

T1 - REDD1 activates a ROS-generating feedback loop in the retina of diabetic mice

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AU - Toro, Allyson L.

AU - Barber, Alistair

AU - Dennis, Michael

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Y1 - 2019/5/1

N2 - PURPOSE. The present study was designed to evaluate the role of the stress response protein REDD1 in diabetes-induced oxidative stress and retinal pathology. METHODS. Wild-type and REDD1-deficient mice were administered streptozotocin to induce diabetes. Some mice received the antioxidant N-acetyl-l-cysteine (NAC). Visual function was assessed by virtual optometry. Retinas were analyzed by Western blotting. Reactive oxygen species (ROS) were assessed by 2,7-dichlorofluoroscein. Similar analyses were performed on R28 retinal cells in culture exposed to hyperglycemic conditions, NAC, and/or the exogenous ROS source hydrogen peroxide. RESULTS. In the retina of diabetic mice, REDD1 expression and ROS were increased. In cells in culture, hyperglycemic conditions enhanced REDD1 expression, ROS levels, and the mitochondrial membrane potential. However, similar effects were not observed in the retina of diabetic mice or cells lacking REDD1. In the retina of diabetic mice and cells exposed to hyperglycemic conditions, NAC normalized ROS and prevented an increase in REDD1 expression. Diabetic mice receiving NAC also exhibited improved contrast sensitivity as compared to diabetic controls. Hydrogen peroxide addition to culture medium increased REDD1 expression and attenuated Akt/GSK3 phosphorylation in a REDD1-dependent manner. In REDD1-deficient cells exposed to hyperglycemic conditions, expression of a dominant negative Akt or constitutively active GSK3 increased the mitochondrial membrane potential and promoted ROS. CONCLUSIONS. The findings provide new insight into the mechanism whereby diabetes-induced hyperglycemia causes oxidative stress and visual dysfunction. Specifically, hyperglycemiainduced REDD1 activates a ROS-generating feedback loop that includes Akt/GSK3. Thus, therapeutic approaches targeting REDD1 expression and ROS may be beneficial for preventing diabetes-induced visual dysfunction.

AB - PURPOSE. The present study was designed to evaluate the role of the stress response protein REDD1 in diabetes-induced oxidative stress and retinal pathology. METHODS. Wild-type and REDD1-deficient mice were administered streptozotocin to induce diabetes. Some mice received the antioxidant N-acetyl-l-cysteine (NAC). Visual function was assessed by virtual optometry. Retinas were analyzed by Western blotting. Reactive oxygen species (ROS) were assessed by 2,7-dichlorofluoroscein. Similar analyses were performed on R28 retinal cells in culture exposed to hyperglycemic conditions, NAC, and/or the exogenous ROS source hydrogen peroxide. RESULTS. In the retina of diabetic mice, REDD1 expression and ROS were increased. In cells in culture, hyperglycemic conditions enhanced REDD1 expression, ROS levels, and the mitochondrial membrane potential. However, similar effects were not observed in the retina of diabetic mice or cells lacking REDD1. In the retina of diabetic mice and cells exposed to hyperglycemic conditions, NAC normalized ROS and prevented an increase in REDD1 expression. Diabetic mice receiving NAC also exhibited improved contrast sensitivity as compared to diabetic controls. Hydrogen peroxide addition to culture medium increased REDD1 expression and attenuated Akt/GSK3 phosphorylation in a REDD1-dependent manner. In REDD1-deficient cells exposed to hyperglycemic conditions, expression of a dominant negative Akt or constitutively active GSK3 increased the mitochondrial membrane potential and promoted ROS. CONCLUSIONS. The findings provide new insight into the mechanism whereby diabetes-induced hyperglycemia causes oxidative stress and visual dysfunction. Specifically, hyperglycemiainduced REDD1 activates a ROS-generating feedback loop that includes Akt/GSK3. Thus, therapeutic approaches targeting REDD1 expression and ROS may be beneficial for preventing diabetes-induced visual dysfunction.

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