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Arap1 loss causes retinal pigment epithelium phagocytic dysfunction and subsequent photoreceptor death.

ABSTRACT: Retinitis pigmentosa (RP), a retinal degenerative disease, is the leading cause of heritable blindness. Previously, we described that Arap1-/- mice develop a similar pattern of photoreceptor degeneration. Arap1 is an Arf-directed GTPase-activating protein shown to modulate actin cytoskeletal dynamics. Curiously, Arap1 expression was detected in Müller glia and retinal pigment epithelium (RPE), but not the photoreceptors themselves. In this study, we generated conditional knockout mice for Müller glia/RPE, Müller glia and RPE via targeting Rlbp1, Glast and Vmd2 promoters, respectively, to drive Cre recombinase expression to knock out Arap1. Vmd2-Cre Arap1tm1c/tm1c and Rlbp1-Cre Arap1tm1c/tm1c mice, but not Glast-Cre Arap1tm1c/tm1c mice, recapitulated the phenotype originally observed in germline Arap1-/- mice. Mass spectrometry analysis of human ARAP1 co-immunoprecipitation identified candidate binding partners of ARAP1, revealing potential interactants involved in phagocytosis, cytoskeletal composition, intracellular trafficking and endocytosis. Quantification of outer segment phagocytosis in vivo demonstrated a clear phagocytic defect in Arap1-/- mice compared to Arap1+/+ controls. We conclude that Arap1 expression in RPE is necessary for photoreceptor survival due to its indispensable function in RPE phagocytosis. This article has an associated First Person interview with the first author of the paper.

SUBMITTER: Shao A

PROVIDER: S-EPMC9346516 | biostudies-literature | 2022 Jul

REPOSITORIES: biostudies-literature

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Arap1 loss causes retinal pigment epithelium phagocytic dysfunction and subsequent photoreceptor death.

Shao Andy A Lopez Antonio Jacobo AJ Chen JiaJia J Tham Addy A Javier Seanne S Quiroz Alejandra A Frick Sonia S Levine Edward M EM Lloyd K C Kent KCK Leonard Brian C BC Murphy Christopher J CJ Glaser Thomas M TM Moshiri Ala A

Disease models & mechanisms 20220725 7

Retinitis pigmentosa (RP), a retinal degenerative disease, is the leading cause of heritable blindness. Previously, we described that Arap1-/- mice develop a similar pattern of photoreceptor degeneration. Arap1 is an Arf-directed GTPase-activating protein shown to modulate actin cytoskeletal dynamics. Curiously, Arap1 expression was detected in Müller glia and retinal pigment epithelium (RPE), but not the photoreceptors themselves. In this study, we generated conditional knockout mice for Müller ...[more]

PMID: 35758026

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Project description:Background: To identify and functionally annotate cell type-specific gene expression in the human retinal pigment epithelium (RPE), a key tissue involved in age-related macular degeneration and retinitis pigmentosa. Methodology: RPE, photoreceptor and choroidal cells were isolated from selected freshly frozen healthy human donor eyes using laser microdissection. RNA isolation, amplification and hybridization to 44k microarrays was carried out according to Agilent specifications. Bioinformatics was carried out using Rosetta Resolver, David and Ingenuity software. Principal Findings: Our previous 22k analysis of the RPE transcriptome showed that the RPE has high levels of protein synthesis, strong energy demands, is exposed to high levels of oxidative stress and a variable degree of inflammation. We currently use a complementary new strategy aimed at the identification and functional annotation of RPE-specific expressed transcripts. This strategy takes advantage of the multilayered cellular structure of the retina and overcomes a number of limitations of previous studies. In triplicate, we compared the transcriptomes of RPE, photoreceptor and choroidal cells and we deduced RPE specific expression. We identified at least 114 entries with RPE-specific gene expression. Thirty-nine of these 114 genes also show high expression in the RPE, comparison with the literature showed that 85% of these 39 were previously identified to be expressed in the RPE. In the group of 114 RPE specific genes there was an overrepresentation of genes involved in (membrane) transport, vision and ophthalmic disease. More fundamentally, we found RPE-specific involvement in the RAR-activation, retinol metabolism and GABA receptor signaling pathways. Conclusions: In this study we provide a further specification and understanding of the RPE transcriptome by identifying and analyzing genes that are specifically expressed in the RPE. Six RPE samples, three phot samples, three choroid samples

Dataset Information

Arap1 loss causes retinal pigment epithelium phagocytic dysfunction and subsequent photoreceptor death.

Publications

Arap1 loss causes retinal pigment epithelium phagocytic dysfunction and subsequent photoreceptor death.

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