The Role of Regulated in Development and DNA Damage Response 1 (REDD1) in Diabetes-Induced NLRP3 Inflammasome Activation and Diabetic Retinopathy

open_access
Open Access
Author:
Mc Curry, Christopher
Graduate Program:
Biomedical Sciences
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
May 28, 2025
Committee Members:
Lisa Shantz, Program Head/Chair
Scot Kimball, Major Field Member
Christopher Yengo, Outside Field Member
Michael Dennis, Chair & Dissertation Advisor
Edward Harhaj, Outside Unit Member
Keywords:
diabetic retinopathy
DDIT4
RTP801
Müller glia
hyperglycemia
Diabetic Retinopathy
REDD1
DDIT4
NLRP3 Inflammasome
Inflammation
Müller glia
Hyperglycemia
RTP801
GSK3β
Priming
Abstract:
Inflammasome activation has been implicated in the development of retinal complications caused by diabetes. This dissertation aimed to elucidate specific signaling pathways that underlie the activation of the NOD-, LRR-, pyrin domain-containing protein 3 (NLRP3) inflammasome and the development of inflammation in the context of diabetic retinopathy (DR). Diabetes was induced in mice via streptozotocin administration, and retinas were examined after 16 weeks. Human MIO-M1 Müller cells were exposed to hyperglycemic culture conditions, and genetic and pharmacological interventions were employed to interrogate signaling pathways. Visual function was assessed using a virtual optomotor system. In the retina of diabetic mice and in Müller cell cultures, NLRP3 and interleukin-1β (IL-1β) were increased in response to hyperglycemic culture conditions, and the stress response protein Regulated in Development and DNA Damage Response 1 (REDD1) was required for the effect. REDD1 deletion prevented caspase-1 activation in Müller cells exposed to hyperglycemic conditions and reduced IL-1β release. REDD1 also promoted nuclear factor κB (NF-κB) signaling in cells exposed to hyperglycemic conditions, which was necessary for the increase in NLRP3. Expression of a constitutively active GSK3β variant restored NLRP3 expression in REDD1-deficient cells exposed to hyperglycemic conditions. GSK3β activity was necessary for increased NLRP3 expression in the retina of diabetic mice and in cells exposed to hyperglycemic conditions. Müller glia-specific REDD1 deletion prevented increased retinal NLRP3 levels and deficits in contrast sensitivity in diabetic mice. These findings identify REDD1 and GSK3β as key regulators of diabetes-induced NLRP3 inflammasome activation in the retina.