title: Selective impairment of a subset of Ran-GTP-binding domains of ran-binding protein 2 (Ranbp2) suffices to recapitulate the degeneration of the retinal pigment epithelium (RPE) triggered by Ranbp2 ablation.
abstract: Retinal pigment epithelium (RPE) degeneration underpins diseases triggered by disparate genetic lesions, noxious insults, or both. The pleiotropic Ranbp2 controls the expression of intrinsic and extrinsic pathological stressors impinging on cellular viability. However, the physiological targets and mechanisms controlled by Ranbp2 in tissue homeostasis, such as RPE, are ill defined. We show that mice, RPE-cre::Ranbp2(-/-), with selective Ranbp2 ablation in RPE develop pigmentary changes, syncytia, hypoplasia, age-dependent centrifugal and non-apoptotic degeneration of the RPE, and secondary leakage of choriocapillaris. These manifestations are accompanied by the development of F-actin clouds, metalloproteinase-11 activation, deregulation of expression or subcellular localization of critical RPE proteins, atrophic cell extrusions into the subretinal space, and compensatory proliferation of peripheral RPE. To gain mechanistic insights into what Ranbp2 activities are vital to the RPE, we performed genetic complementation analyses of transgenic lines of bacterial artificial chromosomes of Ranbp2 harboring loss of function of selective Ranbp2 domains expressed in a Ranbp2(-/-) background. Among the transgenic lines produced, only Tg(RBD2/3*-HA)::RPE-cre::Ranbp2(-/-)-expressing mutations, which selectively impair binding of RBD2/3 (Ran-binding domains 2 and 3) of Ranbp2 to Ran-GTP, recapitulate RPE degeneration, as observed with RPE-cre::Ranbp2(-/-). By contrast, Tg(RBD2/3*-HA) expression rescues the degeneration of cone photoreceptors lacking Ranbp2. The RPE of RPE-cre::Ranbp2(-/-) and Tg(RBD2/3*-HA)::RPE-cre::Ranbp2(-/-) share proteostatic deregulation of Ran GTPase, serotransferrin, and γ-tubulin and suppression of light-evoked electrophysiological responses. These studies unravel selective roles of Ranbp2 and its RBD2 and RBD3 in RPE survival and functions. We posit that the control of Ran GTPase by Ranbp2 emerges as a novel therapeutic target in diseases promoting RPE degeneration.
authors.affiliation: From the Departments of Ophthalmology and.
authors.forename: Hemangi
authors.initials: H
authors.lastname: Patil
authors.affiliation: From the Departments of Ophthalmology and.
authors.forename: Arjun
authors.initials: A
authors.lastname: Saha
authors.affiliation: From the Departments of Ophthalmology and.
authors.forename: Eugene
authors.initials: E
authors.lastname: Senda
authors.affiliation: From the Departments of Ophthalmology and.
authors.forename: Kyoung-in
authors.initials: KI
authors.lastname: Cho
authors.affiliation: From the Departments of Ophthalmology and.
authors.forename: MdEmdadul
authors.initials: M
authors.lastname: Haque
authors.affiliation: the Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195.
authors.forename: Minzhong
authors.initials: M
authors.lastname: Yu
authors.affiliation: From the Departments of Ophthalmology and.
authors.forename: Sunny
authors.initials: S
authors.lastname: Qiu
authors.affiliation: From the Departments of Ophthalmology and.
authors.forename: Dosuk
authors.initials: D
authors.lastname: Yoon
authors.affiliation: From the Departments of Ophthalmology and.
authors.forename: Ying
authors.initials: Y
authors.lastname: Hao
authors.affiliation: the Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, the Research Service, Cleveland Veterans Affairs Medical Center, Cleveland, Ohio 44106, and the Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio 44195.
authors.forename: Neal S
authors.initials: NS
authors.lastname: Peachey
authors.affiliation: From the Departments of Ophthalmology and Pathology, Duke University Medical Center, Durham, North Carolina 27710, paulo.ferreira@duke.edu.
authors.forename: Paulo A
authors.initials: PA
authors.lastname: Ferreira
mesh_terms: D000818:Animals; D002196:Capillaries / Q000473:pathology; D049109:Cell Proliferation; D002470:Cell Survival; D022202:Chromosomes, Artificial, Bacterial / Q000378:metabolism; D018450:Disease Progression; D055724:Electrophysiological Phenomena; D017353:Gene Deletion; D019426:Integrases / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D018832:Molecular Chaperones / Q000737:chemistry* / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D028861:Nuclear Pore Complex Proteins / Q000737:chemistry* / Q000172:deficiency / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D055213:Retinal Pigment Epithelium / Q000378:metabolism* / Q000473:pathology* / Q000503:physiopathology / Q000648:ultrastructure; D013329:Structure-Activity Relationship
chemical_list: D018832:Molecular Chaperones; D028861:Nuclear Pore Complex Proteins; C094493:ran-binding protein 2; C045073:Cre recombinase; D019426:Integrases
keywords: Cell Biology; Cell Death; Cellular Regulation; Electrophysiology; Epithelial Cell; Gene Knockout; Microscopic Imaging; Proteostasis; RNA Regulation; Transgenic Mice