Purchase this article with an account.
Marina Gorbatyuk, Shreyasi Choudhury, Sonali Nashine, Yogesh Bhootada, Alfred Lewin, Oleg Gorbatyuk; Modulation of the rate of retinal degeneration in T17M RHO mice by reprogramming the Unfolded Protein Response. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5949.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Unfolded Protein Response is activated in the ADRP mouse retina expressing misfolded T17M rhodopsin (RHO). Therefore, the goal of this study is to validate whether the UPR could be a therapeutic target and whether the reprogramming of the UPR via modulation of pro-apoptotic caspase-7 and CHOP proteins could be an effective approach to slow down the rate of retinal degeneration in ADRP mice.
One, two, and three-month-old wild-type, CASP-7-/-, T17M RHO CASP7-/-, CHOP-/-, T17M RHO CHOP-/- and T17M RHO mice were used in the study. Evaluation of the impact of CASP7 or CHOP ablations in T17M RHO retina was performed using ERG, SD-OCT, histology, qRT-PCR and western blot analysis. In vivo study with the 661W cells co-transfected with either wt or T17M RHO and control or CASP7 siRNAs were conducted. The RNA and protein extracts were obtained to study the cellular signaling by RT-PCR or immunoblotting.
The scotopic ERG demonstrated that the ablation of the CASP-7 in T17M RHO retina leads to significant preservation of the function of photoreceptors from P30 to P90, compared to control. Surprisingly, the ablation of pro-apoptotic CHOP protein in T17M RHO mice led to a more severe form of retinal degeneration already at 1 month. Results of the SD-OCT and histology were in agreement with the ERG data. The study of the cellular signaling in T17M RHO retina deficient in CASP-7 or CHOP demonstrated that the preservation of the structure and function of T17M RHO photoreceptors or the acceleration of the onset of the T17M RHO photoreceptor degeneration occurred via reprogramming of the UPR. In addition, the CASP-7 ablation led to the inhibition of PARP1-TNFa-TRAF2-cJUN mediated apoptosis, while the ablation of CHOP induced an increase in the HDAC protein. In vitro study also confirmed the modulation of cellular signaling observed in genetically modified ADRP retina.
Our data demonstrated that ablation of either CASP-7 or CHOP reprogram the UPR in T17M RHO retina. The CASP-7 deficit slows down the ADRP progression; the CHOP deficit, however, expedites the retinal degeneration. Therefore, manipulation with the UPR stimulated apoptosis in ADRP retina is an effective approach to modulate the rate of retinal degeneration but requires careful examination in order to achieve a therapeutic effect.
This PDF is available to Subscribers Only