Mutations in splicing factor PRPF3, causing retinal degeneration, form detrimental aggregates in photoreceptor cells
Mutations in splicing factor PRPF3, causing retinal degeneration, form detrimental aggregates in photoreceptor cells
复制标题
DOI：
10.1093/hmg/ddm118
复制
发表时间：
2007-07-15
影响因子：
3.5
通讯作者：
Marigo, Valeria
中科院分区：
文献类型：
--
作者：
Comitato, Antonella;Spampanato, Carmine;Marigo, Valeria
PRPF3是普遍表达的剪接机制的一个元件，然而该基因的突变与组织特异性表型相关：常染色体显性视网膜色素变性（RP）。在这里，我们研究了内源性和突变转染的PRPF3的亚细胞定位。我们发现(1)内源性野生型蛋白的亚细胞分布与小核核糖核蛋白共定位，部分与核核标记共定位，并以SC35标记的斑点聚集；（ii）在人类视网膜中，PRPF3在受RP影响的光感受器细胞中没有显示出明显的丰度；（iii）与野生型蛋白不同，RP引起突变的PRPF3在转染的光感受器细胞中形成异常的大聚集体。T494M突变体PRPF3在细胞核内聚集仅在感光细胞中触发凋亡。基于观察到突变体PRPF3在核仁中积累，以及转录、翻译和蛋白酶体抑制可在非光感受器细胞中诱导这种现象，我们假设突变影响剪接因子的再循环。值得注意的是，突变蛋白的大聚集体积累也影响了其他一些剪接因子的分布。我们的数据表明，突变蛋白在杆状光感受器中具有细胞特异性的显性作用，而似乎对上皮细胞和成纤维细胞无害。
PRPF3 is an element of the splicing machinery ubiquitously expressed, yet mutations in this gene are associated with a tissue-specific phenotype: autosomal dominant retinitis pigmentosa (RP). Here, we studied the subcellular localization of endogenous- and mutant-transfected PRPF3. We found that (1) subcellular distribution of the endogenous wild-type protein co-localizes with small nuclear ribonucleoproteins, partially with a nucleolar marker and accumulates in speckles labeled by SC35; (ii) in human retinas, PRPF3 does not show a distinctive abundance in photoreceptors, the cells affected in RP and (iii) the RP causing mutant PRPF3, differently from the wild-type protein, forms abnormally big aggregates in transfected photoreceptor cells. Aggregation of T494M mutant PRPF3 inside the nucleus triggers apoptosis only in photoreceptor cells. On the basis of the observation that mutant PRPF3 accumulates in the nucleolus and that transcriptional, translational and proteasome inhibition can induce this phenomenon in non-photoreceptor cells, we hypothesize that mutation affects splicing factor recycling. Noteworthy, accumulation of the mutant protein in big aggregates also affects distribution of some other splicing factors. Our data suggest that the mutant protein has a cell-specific dominant effect in rod photoreceptors while appears not to be harmful to epithelial and fibroblast cells.