September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
RPE cell specific loss of ERK1/2 leads to retinal degeneration.
Author Affiliations & Notes
  • Aswin Pyakurel
    Hopital ophtalmique Jules-Gonin, University of Lausanne, Lausanne, Switzerland
    Institute for Research in Ophthalmology, Sion, Switzerland
  • Delphine Balmer
    Institute for Research in Ophthalmology, Sion, Switzerland
  • Mei L Zhu
    University of Oklahoma Health Sciences Center, Oklahama, Oklahoma, United States
  • Marck Saba El Leil
    Université de Montréal, Montreal, Quebec, Canada
  • Jean Daraspe
    University of Lausanne, Lausanne, Switzerland
  • Bruno Humbel
    University of Lausanne, Lausanne, Switzerland
  • Laure Voisin
    Université de Montréal, Montreal, Quebec, Canada
  • Yun-Zheng Le
    University of Oklahoma Health Sciences Center, Oklahama, Oklahoma, United States
  • Johannes Von Lintig
    School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
  • Sylvain Meloche
    Université de Montréal, Montreal, Quebec, Canada
  • Raphael Roduit
    Hopital ophtalmique Jules-Gonin, University of Lausanne, Lausanne, Switzerland
    Institute for Research in Ophthalmology, Sion, Switzerland
  • Footnotes
    Commercial Relationships   Aswin Pyakurel, None; Delphine Balmer, None; Mei Zhu, None; Marck Saba El Leil, None; Jean Daraspe, None; Bruno Humbel, None; Laure Voisin, None; Yun-Zheng Le, None; Johannes Von Lintig, None; Sylvain Meloche, None; Raphael Roduit, None
  • Footnotes
    Support  none
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 3176. doi:
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      Aswin Pyakurel, Delphine Balmer, Mei L Zhu, Marck Saba El Leil, Jean Daraspe, Bruno Humbel, Laure Voisin, Yun-Zheng Le, Johannes Von Lintig, Sylvain Meloche, Raphael Roduit; RPE cell specific loss of ERK1/2 leads to retinal degeneration.. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3176.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : ARMD patients exhibit accumulation of lipofuscin granules as well as phagolysosomes. One of the major components of lipofuscin A2E, regulate ERK1/2 pathway, which is required for the maintenance and proliferation of RPE cells. In order to understand the function of ERK1/2 in the RPE cells, RPE specific knockout of Erk1/2 was carried out.

Methods : Erk1(-/-)/Erk2(fl/fl) (DKO) mouse were crossed with a mice expressing RPE-Cre in a doxycycline dependent manner, to obtain [RPE-Cre-Erk1(-/-)/Erk2(lx/lx) (Cre-DKO)]. Two months post-birth, the mice were injected with Doxycycline. Non-invasive analyses were performed and eyes enucleated for immunohistochemical and biochemical analyses.

Results : On phenotypic level, fundus analysis of Cre-DKO mice showed macular depigmentation and neovascularization. Electroretinogram (ERG) analysis combined with the retinoids measurement showed dysfunctional vision as well as significant decrease in the retinoids content both in the RPE cells and retina. Optical coherence tomography (OCT) analysis confirmed the retinal structural disorganization.
Immunohistochemical analyses demonstrated photoreceptor (PR) loss and decrease in outer nuclear layer (ONL) and inner nuclear layer (INL) to more than half of the original. The decrease in ONL was first due to the loss of cone photoreceptors as investigated by immunostaining, western blot & QPCR analysis. Homogeneity and structure of RPE cells was rapidly modified in Cre-DKO mice as shown by phalloidin staining and electron microscopy analysis. To decipher the molecular mechanism, we investigated the levels of various RPE cells markers. Loss of ERK1/2 led to specific decrease of retinal pigment epithelium-specific protein 65kDa (RPE65) with mislocalization of lecithin retinol acyltransferase (LRAT). This decrease was dependent on the presence of an AP-1 site in RPE65 promoter region and mutation of this site abrogated the decrease.

Conclusions : Specific decrease of ERK1/2 in RPE cells lead to a rapid disorganization of RPE cells, a decrease of retinoids levels, a dowregulation of RPE65 and a mislocaization of LRAT, and finally to retinal degeneration. Here, we show for the first time, an upstream regulator of RPE65, ERK1/2, which is able to directly regulate this RPE marker at transcriptional level.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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