A mutation in the transmembrane/luminal domain of the ryanodine receptor is associated with abnormal Ca2+ release channel function and severe central core disease
A mutation in the transmembrane/luminal domain of the ryanodine receptor is associated with abnormal Ca2+ release channel function and severe central core disease
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DOI：
10.1073/pnas.96.7.4164
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发表时间：
1999-03-30
影响因子：
11.1
通讯作者：
McCarthy, TV
中科院分区：
文献类型：
--
作者：
Lynch, PJ;Tong, JF;McCarthy, TV
中央核心病是一种罕见的非进行性肌病，其特征是肌张力减退和近端肌无力。在一个大型的墨西哥家族异常严重和高度渗透形式的疾病，DNA测序确定了一个14898 T突变的C-末端跨膜/腔区域的RyR 1蛋白，构成骨骼肌兰尼碱受体，所有以前报道的RYR 1突变位于细胞质N端或在中央细胞质区域的5，038-aa蛋白。将14898 T突变引入兔RYR 1 cDNA并在HEK-293细胞中表达。在Ca ~（2+）分光光度法中，突变型RyR_1钙通道对激动剂氟烷和咖啡因的反应完全消失，而正常和突变型RyR_1 cDNA以1：1的比例共表达时，产生的RyR_1通道具有正常的氟烷和咖啡因敏感性，但最大Ca ~（2+）释放水平降低了67%。[H-3]Ryanodine结合表明杂合通道被低于正常的1/2的Ca 2+浓度激活。共转染细胞的单细胞分析显示，静息细胞质Ca 2+水平显着增加，管腔Ca 2+水平显着降低。这些数据表明渗漏通道，可能由通道激活所需的Ca 2+浓度降低引起。与其他两个共表达的突变/正常通道的比较表明，14898 T突变产生的最异常的RyR 1通道之一得到调查，这种水平的异常反映在受影响的中央核心疾病个体的严重和外显表型。
Central core disease is a rare, nonprogressive myopathy that is characterized by hypotonia and proximal muscle weakness. In a large Mexican kindred with an unusually severe and highly penetrant form of the disorder, DNA sequencing identified an 14898T mutation in the C-terminal transmembrane/luminal region of the RyR1 protein that constitutes the skeletal muscle ryanodine receptor, All previously reported RYR1 mutations are located either in the cytoplasmic N terminus or in a central cytoplasmic region of the 5,038-aa protein. The 14898T mutation was introduced into a rabbit RYR1 cDNA and expressed in HEK-293 cells. The response of the mutant RyR1 Ca2+ channel to the agonists halothane and caffeine in a Ca2+ photometry assay was completely abolished, Coexpression of normal and mutant RYR1 cDNAs in a 1:1 ratio, however, produced RyR1 channels with normal halothane and caffeine sensitivities, but maximal levels of Ca2+ release were reduced by 67%. [H-3]Ryanodine binding indicated that the heterozygous channel is activated by Ca2+ concentrations It-fold lower than normal. Single-cell analysis of cotransfected cells showed a significantly increased resting cytoplasmic Ca2+ level and a significantly reduced luminal Ca2+ level. These data are indicative of a leaky channel, possibly caused by a reduction in the Ca2+ concentration required for channel activation. Comparison with two other coexpressed mutant/normal channels suggests that the 14898T mutation produces one of the most abnormal RyR1 channels get investigated, and this level of abnormality is reflected in the severe and penetrant phenotype of affected central core disease individuals.