Abstract
ABSTRACTMutations in RPGRORF15 (retinitis pigmentosa GTPase regulator) are a major cause of inherited retinal degenerative diseases. RPGRORF15 (1152 residues) is a ciliary protein involved in regulating the composition and function of photoreceptor cilia. The mutational hotspot in RPGRORF15 is an unusual C-terminal domain encoded by exon ORF15, which is rich in polyglutamates and glycine residues (Glu-Gly domain) followed by a short stretch of basic amino acid residues (RPGRC2 domain; residues 1072-1152). However, the properties of the ORF15-encoded domain and its involvement in the pathogenesis of the disease are unclear. Here we show that RPGRORF15 is glutamylated at the C-terminus, as determined by binding to GT335, which recognizes glutamylated substrates. This reactivity is lost in two mouse mutants of Rpgr, which do not express RPGRORF15 due to disease-causing mutations in exon ORF15. Our results indicate that RPGRORF15 is posttranslationally glutamylated in the Glu-Gly domain and that the GT335 antibody predominantly recognizes RPGRORF15 in photoreceptor cilia.
Highlights
Retinitis pigmentosa (RP) is a group of genetically and clinically heterogeneous disorders of the eye
Given that RPGR associates with microtubule-based assemblies and that loss of RPGR alters microtubule-based photoreceptor ciliary trafficking (Anand and Khanna, 2012; Rao et al, 2015), we examined whether tubulin modifications are altered in the absence of RPGR
Immunoblot analysis of retinal extracts from wild-type (WT), Rpgrnull, and Rpgrrd9 mouse retinas using antibodies against various post-translationally modified tubulin revealed no changes in the levels of acetylated α-tubulin, detyrosinated tubulin or glutamylated tubulin (B3 and GT335) (Fig. 1A-D)
Summary
Retinitis pigmentosa (RP) is a group of genetically and clinically heterogeneous disorders of the eye. RP is characterized by night blindness due to the loss of rod photoreceptors, followed by complete blindness due the loss of cones (Bird, 1987; Fishman, 1978). X-linked RP is one of the most severe forms with symptoms starting as early as in the first decade of life, which progress into complete blindness usually by the second decade of life (Fishman et al, 1988; Heckenlively et al, 1988). RPGR and RP2, account for >80% of XLRP cases. 15-20% of simplex RP patients carry mutations in RPGR. These data make RPGR a common cause of RP, accounting for ∼20% of all RP cases (Churchill et al, 2013; Daiger et al, 2007)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
