Small GTPase RIT1 in Mouse Retina; Cellular and Functional Analysis

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Abstract

Purpose: Ras-like without CAAX 1 (RIT1/Rit) is a member of the Ras subfamily of small GTP-binding proteins with documented roles in regulating neuronal function, including contributions to neurotrophin signaling, neuronal survival, and neurogenesis. The aim of the study was to (1) examine the expression of RIT1 protein in mouse retina and retinal cell types and (2) determine whether RIT1 contributes to retinal ganglion cell (RGC) survival and synaptic stability following excitotoxic stress. Materials and methods: Gene expression and immunohistochemical analysis were used to examine RIT1 expression in the mouse retina. Primary RGC and Müller glia cultures were used to validate novel RIT1 lentiviral RNAi silencing reagents, and to demonstrate that RIT1 loss does not alter RGC morphology. Finally, in vitro glutamate exposure identified a role for RIT1 in the adaptation of RGCs to excitotoxic stress. Results: Gene expression analysis and immunohistochemical studies in whole eyes and primary cell culture demonstrate RIT1 expression throughout the retina, including Müller glia and RGCs. While genetic RIT1 knockout (RIT1-KO) does not affect gross retinal anatomy, including the thickness of constituent retinal layers or RGC cell numbers, RNAi-mediated RIT1 silencing results in increased RGC death and synaptic loss following exposure to excitotoxic stress. Conclusions: RIT1 is widely expressed in the murine retina, including both Müller glia and RGCs. While genetic deletion of RIT1 does not result in gross retinal abnormalities, these studies identify a novel role for RIT1 in the adaptation of RGC to excitotoxic stress, with RIT1 promoting both neuronal survival and the retention of PSD-95+ synapses.

Original languageEnglish
Pages (from-to)1160-1168
Number of pages9
JournalCurrent Eye Research
Volume43
Issue number9
DOIs
StatePublished - Sep 2 2018

Bibliographical note

Funding Information:
We wish to thank Dr. Michael Mendenhall for generation of recombinant lentiviruses. The authors acknowledge the use of facilities in the University of Kentucky, Center for Molecular Medicine Genetic Technologies Core, supported by NIH Grant P30GM110787.

Funding Information:
This work was supported in part by National Institutes of Health Grant [R01 NS102196] (DAA), the Kentucky Spinal Cord and Head Injury Research Trust (Grants 12-1A and 16-1) (DAA), a grant from the Kentucky Lung Cancer Research Grant (DAA) [P-02 414], and National Institute of Neurological Disorders and Stroke [NS102196]. The funders had no role in study design, data collection and analysis, or preparation of the manuscript.

Publisher Copyright:
© 2018, © 2018 Taylor & Francis Group, LLC.

Keywords

  • Müller glia
  • Ras GTPase
  • excitotoxicity
  • neuronal death
  • retina

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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