RESUMEN

Mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene cause X-linked retinitis pigmentosa type 3 (RP3), a severe, progressive and degenerative retinal dystrophy eventually leading to complete blindness. RPGR is ubiquitously expressed, yet mutations in the RPGR gene lead to a retina-restricted phenotype. To date, all RP3 associated missense mutations that have been identified are located in the RCC1-homologous domain (RHD) of RPGR. To investigate the molecular pathogenesis of RP3, we screened retinal yeast two-hybrid libraries with the RHD of RPGR. We identified several alternatively spliced gene products, some with retina-restricted expression, that interact specifically with RPGR in vivo and in vitro. Thus, these proteins were named RPGR-interacting protein 1 (RPGRIP1) isoforms. They contain a C-terminal RPGR-interacting domain and stretches of variable coiled-coil domains homologous to proteins involved in vesicular trafficking. The interaction between RPGR and RPGRIP1 isoforms was impaired in vivo by RP3-associated mutations in RPGR. Moreover, RPGR and RPGRIP1 co-localize in the outer segment of rod photoreceptors, which is in full agreement with the retinitis pigmentosa phenotype observed in RP3 patients. The localization of RPGRIP1 at 14q11 makes it a strong candidate gene for RP16. These results provide a clue for the retina-specific pathogenesis in RP3, and hint towards the involvement of RPGR and RPGRIP1 in mediating vesicular transport-associated processes.

Asunto(s)

Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Proteínas del Ojo , Mutación , Proteínas/genética , Células Fotorreceptoras Retinianas Bastones/metabolismo , Regiones no Traducidas 3' , Empalme Alternativo , Secuencia de Aminoácidos , Animales , Northern Blotting , Western Blotting , Proteínas Portadoras/química , Bovinos , Sistema Libre de Células , Cromosomas Humanos Par 14 , Proteínas del Citoesqueleto , Glutatión Transferasa/metabolismo , Humanos , Inmunohistoquímica , Modelos Genéticos , Datos de Secuencia Molecular , Mutación Missense , Fenotipo , Plásmidos/metabolismo , Pruebas de Precipitina , Biosíntesis de Proteínas , Isoformas de Proteínas , Estructura Terciaria de Proteína , Retina/metabolismo , Células Fotorreceptoras Retinianas Bastones/química , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Homología de Secuencia de Aminoácido , Temperatura , Distribución Tisular , Activación Transcripcional , Técnicas del Sistema de Dos Híbridos