Abstract
Purpose :
REEP6, a receptor enhancer protein, is required for normal function of rod photoreceptors. REEP6 mutation is associated with Retinitis Pigmentosa in human. In this study, we generated Reep6 knockout mice to further study the function of Reep6 in retina.
Methods :
Reep6-/- mouse were created using CRISPR/CAS9 technique. For western blot, mouse retinal proteins were extracted and was probed with primary antibodies against rhodopsin, GC1, PDE6B, REEP6, GRK1, and AMPK. For immunohistochemistry, eyes were fixed, cryosectioned, and probed with rhodopsin, GC1, PDE6B, GRK1, and REEP6 antibodies. Retinal ATP was measured by using the ADP-GLO Max Assay kit (Promega).
Results :
REEP6 protein is abundantly expressed in inner segments and synaptic terminals of rod photoreceptors. Deletion of Reep6 led to progressive retinal degeneration. The amplitudes of the scotopic a-wave and the b-wave were reduced in Reep6-/- mice at p21. Upon loss of Reep6 in mice, expression of Rhodpsin, GC1, and GRK1 was dramatically decreased, whereas there was no effect on PDE6 expression. Trafficking of Rhodopsin, GC1, PDE6, and GRK1 to outer segment was normal. The ATP level was elevated in Reep6-/- mouse retina. Phosphorylation of AMPK, a kinase detecting intracellular ATP/AMP ratio was attenuated in Reep6-/- mouse retina.
Conclusions :
REEP6 is critical for expression of phototranduction proteins and regulates oxidative phosphorylation in rod photoreceptors.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.