title: Usher syndrome and Leber congenital amaurosis are molecularly linked via a novel isoform of the centrosomal ninein-like protein.
abstract: Usher syndrome (USH) and Leber congenital amaurosis (LCA) are autosomal recessive disorders resulting in syndromic and non-syndromic forms of blindness. In order to gain insight into the pathogenic mechanisms underlying retinal degeneration, we searched for interacting proteins of USH2A isoform B (USH2A(isoB)) and the LCA5-encoded protein lebercilin. We identified a novel isoform of the centrosomal ninein-like protein, hereby named Nlp isoform B (Nlp(isoB)), as a common interactor. Although we identified the capacity of this protein to bind calcium with one of its three EF-hand domains, the interacton with USH2A(isoB) did not depend on this. Upon expression in ARPE-19 cells, recombinant Nlp(isoB), lebercilin and USH2A(isoB) were all found to co-localize at the centrosomes. Staining of retinal sections with specific antibodies against all three proteins revealed their co-localization at the basal bodies of the photoreceptor-connecting cilia. Based on this subcellular localization and the nature of their previously identified binding partners, we hypothesize that the pathogenic mechanisms for LCA and USH show significant overlap and involve defects in ciliogenesis, cilia maintenance and intraflagellar and/or microtubule-based transport. The direct association of Nlp(isoB) with USH2A(isoB) and lebercilin indicates that Nlp can be considered as a novel candidate gene for USH, LCA and allied retinal ciliopathies.
authors.affiliation: Department of Otorhinolaryngology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: Erwin
authors.initials: E
authors.lastname: van Wijk
authors.forename: Ferry F J
authors.initials: FF
authors.lastname: Kersten
authors.forename: Aileen
authors.initials: A
authors.lastname: Kartono
authors.forename: Dorus A
authors.initials: DA
authors.lastname: Mans
authors.forename: Kim
authors.initials: K
authors.lastname: Brandwijk
authors.forename: Stef J F
authors.initials: SJ
authors.lastname: Letteboer
authors.forename: Theo A
authors.initials: TA
authors.lastname: Peters
authors.forename: Tina
authors.initials: T
authors.lastname: Märker
authors.forename: Xiumin
authors.initials: X
authors.lastname: Yan
authors.forename: Cor W R J
authors.initials: CW
authors.lastname: Cremers
authors.forename: Frans P M
authors.initials: FP
authors.lastname: Cremers
authors.forename: Uwe
authors.initials: U
authors.lastname: Wolfrum
authors.forename: Ronald
authors.initials: R
authors.lastname: Roepman
authors.forename: Hannie
authors.initials: H
authors.lastname: Kremer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D029242:Optic Atrophy, Hereditary, Leber / Q000235:genetics / Q000378:metabolism*; D010786:Photoreceptor Cells / Q000378:metabolism; D011485:Protein Binding; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000378:metabolism; D016415:Sequence Alignment; D020798:Two-Hybrid System Techniques; D052245:Usher Syndromes / Q000235:genetics / Q000378:metabolism*
chemical_list: D016326:Extracellular Matrix Proteins; D005136:Eye Proteins; C522405:LCA5 protein, human; D008869:Microtubule-Associated Proteins; C476755:NINL protein, human; D009687:Nuclear Proteins; D020033:Protein Isoforms; C112735:USH2A protein, human