HARVARD DEPARTMENT OF OPHTHALMOLOGY
Category : Basic and Translational Research Candidate : Monica Akula Poster #: B1
Altered Transcription Kinetics Drives Save or Abort Decision for Retinal Cell Fate in Retinitis Pigmentosa : Reset with Modifier Gene Therapy
M . Akula , P . Kadam , S . Bhambra , O . Dube , M . Alejandro , S . Li , Z . Love , K . Holton , M . DeAngelis , N . B . Haider
Purpose : Retinitis pigmentosa ( RP ) is a large group of genetically heterogeneous disorders that result in severe vision loss . Our prior and recent in silico and in vivo analysis revealed that Nr2e3 regulates several key biological networks that are critical to maintaining homeostasis in the retina . In this study we determine the expression profiles of the key retinal transcription regulators such as Nr2e3 , Nr1d1 , Nrl , Crx , Rora and Thrb in multiple RP models before and after treatment with AAV-Nr2e3 therapy .
Methods : RNA was isolated from retinas of several RP models including Nr2e3rd7 / rd7 , Pde6βrd1 , Rho- / - , RhoP23H , RhoP347S and Cep290rd16 . Gene expression profiling of key regulator genes was carried out by RNA-Seq ( n = 3 ) and quantitative real-time PCR ( n≥7 ). Controls included B6 ( normal ) retinas , and untreated retinas were compared to AAV-Nr2e3 treated retinas .
Results : Monogenic diseases such as RP have been studied for the loss of single genes . However , our studies revealed that there is significant downregulation in expression of key retina transcription factors in several models of RP . This shift in turn caused misregulation of key homeostasis gene networks as disease progressed in each model , and this mutational load of the system likely contributes to disease . AAV-Nr2e3 therapy attenuated retinal degeneration in each of these models and resulted in increased expression of key retinal transcription factors and a reset of retinal homeostasis .
Conclusions : This is the first report evaluating the impact of transcriptome kinetics on retinal degeneration using RNA-seq and remodeling of the retina transcriptome following modifier gene therapy . The primary mutation causes a shift of transcription kinetics , forcing the retina to make a save or abort decision early in disease , leading to progressive photoreceptor degeneration . This combinatorial mutational load including the primary mutation and key retinal transcription factor modulation determines phenotypic outcome of each disease . This study further shows the profound impact of AAV-Nr2e3 modifier gene therapy in attenuating retinal disease in a mutation agnostic manner .