HARVARD DEPARTMENT OF OPHTHALMOLOGY
Category : Basic and Translational Research Candidate : Meenakshi Maurya Poster #: B16
REV-ERBα Deficiency Accelerates Age-Related Synaptic Remodeling in Mouse Retina
Meenakshi Maurya *, Chi-Hsiu Liu *, Shuo Huang , Felix Yemanyi , Kiran Bora , Alexandra K . Blomfield , Jing Chen
Purpose : Synaptic remodeling occurs during aging in both humans and mice , leading to neuronal dysfunction . Age-related alterations in the outer retinal synapses have been investigated as a model system to study agedependent neuronal and synaptic modifications such as in AMD . The role of REV-ERBα has been reported in synaptic strengthening in mice model of Alzheimer ’ s disease . REV-ERBα , a nuclear receptor and transcription factor , regulates multiple biological processes including circadian rhythm , metabolism and neuronal function . The present study aimed to explore whether REV-ERBα regulates age-related retinal synaptic alterations using REV-ERBα knockout ( KO ) mice as a model .
Methods : 5- and 11- month-old wild-type ( WT ) and systemic REV-ERBα KO mice were used . Retinal cross sections were immunostained with rod bipolar cell marker Protein kinase C ( PKC-α ) and pre-synaptic protein synaptophysin antibody to assess synaptic alterations . The number and length of ectopic rod bipolar cell dendrite sprouts were quantified . REV-ERBα localization was analyzed with REV-ERBα antibody immunostaining in WT retinas and with β-Gal reporter staining in REV-ERBα KO retinas . Expression of REV- ERBα in retinal cells was assessed using an online single cell RNA sequencing ( scRNA seq ) database . RTqPCR was performed in WT and REV-ERBα KO retinas to evaluate expression of genes involved in cellular energy homeostasis and axonal growth .
Results : REV-ERBα was localized in both outer and inner nuclear layer with REV-ERBα immunostaining . scRNA seq analysis also indicated expression of REV-ERBα in both rod photoreceptors and bipolar cells . The present study showed an accelerated retraction of rod axons accompanied with increase in both the number and length of ectopic rod bipolar cell dendrite sprouts extending into the photoreceptor layer by synaptophysin and PKC-α co-localization in REV-ERBα KO retinas that were significantly increased compared to WT in 5- and 11-months old mice . REV-ERBα KO retinas exhibited significantly decreased expression of multiple genes involved in cellular energy and metabolic regulation .
Conclusions : Our findings suggest that genetic loss of REV-ERBα accelerates age-related synaptic remodeling in the outer retina , possibly through modulating expression of genes controlling cellular energy and metabolism to mediate axonal retraction and dendrite growth .