Dominant, gain-of-function mutant produced by truncation of RPGR
Dominant, gain-of-function mutant produced by truncation of RPGR
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DOI：
10.1167/iovs.03-0787
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发表时间：
2004-01-01
影响因子：
4.4
通讯作者：
Li, TS
中科院分区：
文献类型：
--
作者：
Hong, DH;Pawlyk, BS;Li, TS
目的.视网膜色素变性GTGR调节剂（RPGR）在维持感光细胞活力中是必不可少的。X连锁RPGR基因的突变通常被认为是隐性的。本研究旨在探讨某些突变型RPGR等位基因是否可能起显性作用。将代表RPGR ORF 15变体的RPGR转基因置于非组织特异性启动子下并引入转基因小鼠中。将转基因杂交到野生型（WT）和RPGR无效背景中。通过RT-PCR、免疫印迹分析和免疫荧光分析其表达。通过视网膜电图和组织学评估感光细胞存活率。RPGR转基因转录物经历涉及ORF 15外显子的富含嘌呤区域的光受体特异性选择性剪接，产生缩短的mRNA和提前终止密码子。这种截短突变体比RPGR无效（敲除）突变体引起更快的感光细胞变性。无论转基因与WT RPGR共表达还是在RPGR空背景下单独表达，病程都是相似的。某些截短形式的RPGR可以表现为显性的功能获得性突变体。这些数据表明，人类PPGR突变不一定是无效的，有些也可能作为显性等位基因，导致比无效突变更严重的表型。
PURPOSE. The retinitis pigmentosa GTPase regulator (RPGR) is essential in the maintenance of photoreceptor viability. Mutations in the X-linked RPGR gene have generally been assumed to be recessive. This study was undertaken to investigate whether certain mutant RPGR alleles may act dominantly.METHODS. An RPGR transgene representing the RPGR ORF15 variant was placed under a non-tissue-specific promoter and introduced into transgenic mice. The transgene was crossed into both a wild type (WT) and an RPGR null background. Its expression was analyzed by RT-PCR, immunoblot analysis, and immunofluorescence. Photoreceptor survival was assessed by electroretinography and histology.RESULTS. The RPGR transgene transcript underwent photoreceptor-specific, alternative splicing involving the purine-rich region of the ORF 15 exon, generating a shortened mRNA and a premature stop codon. This truncation mutant caused more rapid photoreceptor degeneration than that in the RPGR null (knockout) mutant. The disease course was similar, whether the transgene was coexpressed with WT RPGR or expressed alone in the RPGR null background.CONCLUSIONS. Certain truncated forms of RPGR can behave as a dominant, gain-of-function mutant. These data suggest that human PPGR mutations are not necessarily null and some may also act as dominant alleles, leading to a more severe phenotype than a null mutant.