Carvajal J J, Pook M A, Doudney K, Hillermann R, Wilkes D, al-Mahdawi S, Williamson R, Chamberlain S
Department of Biochemistry and Molecular Genetics, St Mary's Hospital Medical School, Imperial College, London, UK.
Hum Mol Genet. 1995 Aug;4(8):1411-9. doi: 10.1093/hmg/4.8.1411.
We have previously assigned the mutation causing Friedreich's ataxia (FRDA) to 9q13 by genetic linkage and fluorescent in situ hybridization analysis, and identified recombination events which position the gene centromeric to D9S5. We report here the extension of a yeast artificial chromosome contig to span the 860 kb interval immediately proximal to this marker, which includes the D9S886 and D9S887/888 loci reported to flank the FRDA locus, and the construction of a high resolution cosmid contig initiated from the D9S888 locus. Exon trapping and cDNA library screening strategies have resulted in the isolation of a candidate gene which traverses the centromeric boundary of the FRDA critical region. The gene spans a genomic interval greater than 220 kb with at least two of the coding exons located proximal to the D9S887/888 loci. Expression is complex, with multiple transcripts detected in a variety of tissues and evidence of alternative splicing and developmental control. The predicted amino acid sequence for the 2.7 kb transcript reported here shows a marked homology to the deduced amino acid sequence of the Saccharomyces cerevisiae MSS4 protein, proposed to function within the phosphoinositide cycle, suggesting a potential role for the human homologue in signal transduction. Whilst no evidence for mutation has been detected in this transcript, the sequence represents only one of the shorter alternatively spliced species identified by Northern analysis and direct sequencing. This gene remains a strong candidate for FRDA.
我们先前通过遗传连锁和荧光原位杂交分析，将导致弗里德赖希共济失调（FRDA）的突变定位于9q13，并确定了一些重组事件，这些事件将该基因定位在D9S5的着丝粒侧。我们在此报告，将酵母人工染色体重叠群扩展至紧邻该标记的860 kb区间，该区间包括据报道位于FRDA基因座两侧的D9S886和D9S887/888基因座，并构建了一个从D9S888基因座起始的高分辨率黏粒重叠群。外显子捕获和cDNA文库筛选策略已导致分离出一个跨越FRDA关键区域着丝粒边界的候选基因。该基因跨越一个大于220 kb的基因组区间，其中至少有两个编码外显子位于D9S887/888基因座的近端。其表达较为复杂，在多种组织中检测到多种转录本，并有选择性剪接和发育调控的证据。本文报道的2.7 kb转录本的预测氨基酸序列与酿酒酵母MSS4蛋白的推导氨基酸序列有显著同源性，推测该蛋白在磷酸肌醇循环中发挥作用，这表明人类同源物在信号转导中可能具有潜在作用。虽然在该转录本中未检测到突变证据，但该序列仅代表通过Northern分析和直接测序鉴定出的较短选择性剪接变体之一。该基因仍是FRDA的有力候选基因。
