Purchase this article with an account.
Songhua Li, William C Gordon, Nicolas G Bazan, Minghao Jin; Identification of RPE65 as an Action Point of Fatty Acids Transport Protein 4 in Mouse Models of Leber Congenital Amaurosis. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2385.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
We have previously shown that deletion of fatty acids transport protein 4 (FATP4) significantly enhances 11-cis-retinal (11cRAL) synthesis and rod visual function in the RPE65 R91W knock-in (KI) mouse model of Leber congenital amaurosis (LCA). However, the mechanism by which FATP4-deficincy preserves the visual cycle and rod function in the KI mouse remains unclear. The purpose of this study is to identify the action point of FATP4 in KI mouse.
We generated Fatp4-/- mice in RPE65-deficient (rd12) background. We then compared the visual cycle, retinal structure and scotopic electroretinograms (ERG) in rd12;Fatp4-/- mice with those in rd12, KI and KI;Fatp4-/- mice. Both KI and KI;Fatp4-/- mice are homozygous for the Leu450 allele in the Rpe65 gene. All experiments were performed using 6~8-week-old mice. Expression levels of proteins in the neural retina and retinal pigment epithelium (RPE) were analyzed by immunoblot analysis. The rates of the visual cycle were determined by measuring synthesis of 11cRAL in mice adapted to dark for different times. Retinoids were analyzed by high performance liquid chromatography. ERG responses of dark-adapted mice were evoked by a series of white light flashes (-1~2 log cd.s/m2).
Expression levels of LRAT in the rd12;Fatp4-/- mouse RPE were similar to those in age-matched RPE of rd12, KI and KI;Fatp4-/- mice. FATP4-deficiency significantly increased expression levels of rhodopsin in the KI;Fatp4-/- mouse retina, but not in the rd12;Fatp4-/- retina, as compared to the retinas of KI and rd12 mice, respectively. Amounts of 11cRAL in dark-adapted KI;Fatp4-/- mice were increased 2-fold compared to those in KI mice. FATP4-deficienct, however, did not increase 11cRAL contents in dark-adapted rd12;Fatp4-/- mice. Similar to rd12 mice, rd12;Fatp4-/- mice contained undetectable 11cRAL. The visual cycle rates were also significantly accelerated in KI;Fatp4-/- mice, but not in rd12;Fatp4-/- mice. Consistent with these results, deletion of FATP4 significantly increased light responses of rod photoreceptors in KI mice, but not in rd12 mice.
Partial rescue of the function of R91W mutant RPE65 is the main mechanisms by which FATP4-deficiency enhances chromophore synthesis as well as rod survival and function in the KI mouse model of LCA.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
This PDF is available to Subscribers Only