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Structural organization and expression pattern of the canine RPGRIP1 isoforms in retinal tissue.

ABSTRACT: To examine the structure and expression of RPGRIP1 in dog retina.Determination of the structural analysis and expression pattern of canine RPGRIP1 (cRPGRIP1) was based on cDNA amplification. Absolute quantification of the expression level of cRPGRIP1 splice variants was determined by qRT-PCR. Regulatory structures were examined by computational analysis of comparative genomics.cRPGRIP1 encompasses 25 exons that harbor a 3627-bp open reading frame (ORF) encoding a 1209-amino-acid (aa)-predicted protein. In addition to the main transcript, five full-length and several partial cRPGRIP1 isoforms were identified revealing four alternative 3'-terminal exons--24, 19a, 19c, and 19d--three of which could potentially produce C-terminally truncated proteins that lack the RPGR-interacting domain. A complex organization of the 5'-UTR for the cRPGRIP1 splice products have been described, with a common promoter driving multiple isoforms, including four full-length transcripts using the 3'-terminal exon 24. In addition, a potential alternative internal promoter was revealed to initiate at least two cRPGRIP1 splice variants sharing the same 3'-terminal exon 19c. Transcription initiation sites were highly supported by conserved arrangements of cis-elements predicted in a bioinformatic analysis of orthologous RPGRIP1 promoter regions.The use of alternative transcription start and termination sites results in substantial heterogeneity of cRPGRIP1 transcripts, many of which are likely to have tissue-specific expression. The identified exon-intron structure of cRPGRIP1 isoforms provides a basis for evaluating the gene defects underlying inherited retinal disorders in dogs.

SUBMITTER: Kuznetsova T

PROVIDER: S-EPMC3109012 | biostudies-literature | 2011 May

REPOSITORIES: biostudies-literature

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Structural organization and expression pattern of the canine RPGRIP1 isoforms in retinal tissue.

Kuznetsova Tatyana T Zangerl Barbara B Goldstein Orly O Acland Gregory M GM Aguirre Gustavo D GD

Investigative ophthalmology & visual science 20110506 6

<h4>Purpose</h4>To examine the structure and expression of RPGRIP1 in dog retina.<h4>Methods</h4>Determination of the structural analysis and expression pattern of canine RPGRIP1 (cRPGRIP1) was based on cDNA amplification. Absolute quantification of the expression level of cRPGRIP1 splice variants was determined by qRT-PCR. Regulatory structures were examined by computational analysis of comparative genomics.<h4>Results</h4>cRPGRIP1 encompasses 25 exons that harbor a 3627-bp open reading frame ( ...[more]

PMID: 21282582

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Project description:Mutations affecting the retinitis pigmentosa GTPase regulator-interacting protein 1 (RPGRIP1) interactome cause syndromic retinal dystrophies. RPGRIP1 interacts with the retinitis pigmentosa GTPase regulator (RPGR) through a domain homologous to RCC1 (RHD), a nucleotide exchange factor of Ran GTPase. However, functional relationships between RPGR and RPGRIP1 and their subcellular roles are lacking. We show by molecular modeling and analyses of RPGR disease-mutations that the RPGR-interacting domain (RID) of RPGRIP1 embraces multivalently the shared RHD of RPGR(1-19) and RPGR(ORF15) isoforms and the mutations are non-overlapping with the interface found between RCC1 and Ran GTPase. RPGR disease-mutations grouped into six classes based on their structural locations and differential impairment with RPGRIP1 interaction. RPGRIP1?(1) expression alone causes its profuse self-aggregation, an effect suppressed by co-expression of either RPGR isoform before and after RPGRIP1?(1) self-aggregation ensue. RPGR(1-19) localizes to the endoplasmic reticulum, whereas RPGR(ORF15) presents cytosolic distribution and they determine uniquely the subcellular co-localization of RPGRIP1?(1). Disease mutations in RPGR(1) (-19), RPGR(ORF15), or RID of RPGRIP1?(1), singly or in combination, exert distinct effects on the subcellular targeting, co-localization or tethering of RPGRIP1?(1) with RPGR(1-19) or RPGR(ORF15) in kidney, photoreceptor and hepatocyte cell lines. Additionally, RPGR(ORF15), but not RPGR(1-19), protects the RID of RPGRIP1?(1) from limited proteolysis. These studies define RPGR- and cell-type-dependent targeting pathways with structural and functional plasticity modulating the expression of mutations in RPGR and RPGRIP1. Further, RPGR isoforms distinctively determine the subcellular targeting of RPGRIP1?(1,) with deficits in RPGR(ORF15)-dependent intracellular localization of RPGRIP1?(1) contributing to pathomechanisms shared by etiologically distinct syndromic retinal dystrophies.

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Dataset Information

Structural organization and expression pattern of the canine RPGRIP1 isoforms in retinal tissue.

Publications

Structural organization and expression pattern of the canine RPGRIP1 isoforms in retinal tissue.

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