Molecular biological studies of ryanodine receptor/calcium release channel

本研究的目的是在整体动物水平上阐明兰尼定受体/钙释放通道的生理功能。因此，我们首先尝试寻找或产生兰尼定受体基因突变的动物。鉴于果蝇系统中已知的突变体很多，我们分析了果蝇的兰尼定受体基因，并进行了染色体定位(FEBS)。337，81)；然而，在所定位的染色体位置上没有已知的突变。然后，我们尝试用胚胎干细胞来制备缺乏骨骼肌兰尼定受体的突变小鼠。在对产生的突变小鼠的第一次分析中，我们表明骨骼肌兰尼定受体是肌肉成熟和兴奋-收缩偶联的必要分子(自然369,556)。电子显微镜在变种肌肉中发现了横管和肌浆网膜之间的三联体连接，尺寸很小，这表明骨骼肌兰尼定受体决定了膜之间的大小，但对连接的产生不是必需的(Proc.Natl.Academy.Science.USA.92,3391)。此外，我们在突变的肌肉中发现了脑型ryanodine受体的表达，并揭示了它的药理特性伴随着不能贡献骨骼肌兴奋-收缩偶联(EMBO J.14,2999)。综上所述，我们通过对基因敲除小鼠的产生和分析，定义了骨骼肌ryanodine受体的生理功能，并展示了ryanodine受体亚型之间的区别作用。

The aim of this research is elucidating physiological functions of teh ryanodine receptor/calcium ralease channel in a whole animallevel. Thus, we first tried to find or generate mutant animals in the ryanodine receptor gene. Because so many mutants are known in fruit fly system, we analyzed a ryanodine receptor gene in Drosophila melanogaster and the chromosomal mapping was done (FEBS) Lett. 337,81) ; however, no mutant is known at the located chromosomal position. Then, we tried to prepare mutnat mice lacking the skeletal muscle ryanodine receptor using embyonic stem cells. In the first analysis of the generated mutant mice, we showed that the skeletal muscle ryanodine receptor is an essential molecule for muscle maturation and excitation-contraction coupling (Nature 369,556). An electron-microscopy found triad juctions with a narrow size between transverse-tuble and sarcoplasmi reticulum membranes in the mutnat muscle, indicationg that the skeletal muscle ryanodine receptor determines the size between the membranes but is not essential for generation of the junction (Proc.Natl.Acad.Sci.USA.92,3391). Moreover, we found expression of the brain-type of ryanodine receptor in mutant muscle, and revealedits pharmoacological properties accompanying inability to contribute skeletal muscle exicitation-conrtraction couplina (EMBO J.14,2999).In summary, we defined the phisiological function of the skeletal muscle ryanodine receptor by generation and analysis of knockout mice, and showed the differential role between ryanodine receptor shbtypes.