Sajad Mir1, Douglas A Andres1. 1. a Department of Molecular and Cellular Biochemistry , University of Kentucky, College of Medicine , Lexington , Kentucky , US.
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.
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.
Authors: M Koenighofer; C Y Hung; J L McCauley; J Dallman; E J Back; I Mihalek; K W Gripp; K Sol-Church; P Rusconi; Z Zhang; G-X Shi; D A Andres; O A Bodamer Journal: Clin Genet Date: 2015-06-04 Impact factor: 4.438
Authors: I Arroyo-Carrera; M Solo de Zaldivar-Tristancho; R Martin-Fernandez; M Vera-Torres; J F Gonzalez de Buitrago-Amigo; J Botet-Rodriguez Journal: Rev Neurol Date: 2016-10-16 Impact factor: 0.870
Authors: Claire Hippert; Anna B Graca; Amanda C Barber; Emma L West; Alexander J Smith; Robin R Ali; Rachael A Pearson Journal: PLoS One Date: 2015-03-20 Impact factor: 3.240
Authors: Shereen Nizari; Li Guo; Benjamin M Davis; Eduardo M Normando; Joana Galvao; Lisa A Turner; Mukhtar Bizrah; Mohammad Dehabadi; Kailin Tian; M Francesca Cordeiro Journal: Cell Death Dis Date: 2016-12-08 Impact factor: 8.469