Chatr-Aryamontri Andrew, Angelini Mara, Garelli Emanuela, Tchernia Gil, Ramenghi Ugo, Dianzani Irma, Loreni Fabrizio
Department of Biology, University Tor Vergata, Roma, Italy.
Hum Mutat. 2004 Dec;24(6):526-33. doi: 10.1002/humu.20117.
Mutations in the ribosomal protein (RP)S19 gene have been found in about 25% of the cases of Diamond-Blackfan anemia (DBA), a rare congenital hypoplastic anemia that includes variable physical malformations. Various mutations have been identified in the RPS19 gene, but no investigations regarding the effect of these alterations on RPS19 mRNA levels have been performed. It is well established that mutated mRNA containing a premature stop codon (PTC) or lacking a stop codon can be rapidly degraded by specific mechanisms called nonsense mediated decay (NMD) and nonstop decay. To study the involvement of such mechanisms in DBA, we analyzed immortalized lymphoblastoid cells and primary fibroblasts from patients presenting different kinds of mutations in the RPS19 gene, generating allelic deletion, missense, nonsense, and nonstop messengers. We found that RPS19 mRNA levels are decreased in the cells with allelic deletion and, to a variable extent, also in all the cell lines with PTC or nonstop mutations. Further analysis showed that translation inhibition causes a stabilization of the mutated RPS19 mRNA. Our findings indicate that NMD and nonstop decay affect the expression of mutated RPS19 genes; this may help to clarify genotype-phenotype correlations in DBA.
在约25%的先天性纯红细胞再生障碍性贫血（DBA）病例中发现了核糖体蛋白（RP）S19基因突变，DBA是一种罕见的先天性再生障碍性贫血，伴有多种身体畸形。RPS19基因已鉴定出多种突变，但尚未对这些改变对RPS19 mRNA水平的影响进行研究。众所周知，含有提前终止密码子（PTC）或缺乏终止密码子的突变mRNA可通过称为无义介导衰变（NMD）和无终止衰变的特定机制迅速降解。为了研究这些机制在DBA中的作用，我们分析了来自RPS19基因存在不同类型突变的患者的永生化淋巴母细胞和原代成纤维细胞，产生了等位基因缺失、错义、无义及无终止信使。我们发现，等位基因缺失的细胞中RPS19 mRNA水平降低，在所有含有PTC或无终止突变的细胞系中也有不同程度的降低。进一步分析表明，翻译抑制导致突变的RPS19 mRNA稳定。我们的研究结果表明，NMD和无终止衰变影响突变RPS19基因的表达；这可能有助于阐明DBA中的基因型-表型相关性。
