Abnormality of sugar/amino acid transport and ATP sensor in renal carcinogenesis

据报道，Eker大鼠遗传性肾癌（RC）的致病基因Tsc 2基因的产物在营养和/或能量调节的信号转导中起作用。我们发现，Bhd基因的产物，这是日本大鼠的遗传性RC的致病基因，显示部分氨基酸序列的相似性与酿酒酵母的LST 7产品的氨基端的一半。酵母LST 7基因突变体已被报道在膜转运系统中显示缺陷。我们发现LST 7破坏酵母对雷帕霉素的敏感性略高于野生型酵母。然而，到目前为止，在对毒性氨基酸类似物的抗性程度上没有观察到明显的差异。将大鼠野生型或羧基端截短的卵泡素表达质粒引入突变酵母菌中不能恢复正常的雷帕霉素敏感性。我们正在分析LST 7突变体的其他表型以及哺乳动物卵泡素表达在哺乳动物中的作用。 ...更多信息 突变酵母为了利用哺乳动物细胞分析卵泡素的功能，我们建立并分析了Bhd缺陷型肾癌细胞系（1B系列），其中大鼠Bhd cDNA通过tet-off系统表达。与导入空载体的对照细胞（1 R系列）相比，1B细胞没有表现出明显的生长抑制。转运子如Gluts的表达没有显著变化。然而，1B和1 R细胞表现出不同的形态表型。在相差显微镜下，细胞的粘附和铺展各不相同。通过免疫共沉淀实验，我们初步发现非肌肉肌球蛋白与抗Bhd抗体以1B细胞特异性方式共沉淀。一个合理的假设是，Bhd产品调节细胞骨架成分以及膜运输系统。通过这些功能，Bhd可以调节营养或能量调节的信号转导。我们将阐明Bhd产物的功能及其与营养/能量调节信号以及Tsc 2产物的关系。少

It has been reported that the product of Tsc2 gene, which is the causative gene for the hereditary renal carcinoma (RC) of the Eker rat, functions in nutrient- and/or energy-regulated signal transduction. We found that the product of Bhd gene, which is the causative gene for the hereditary RC of the Nihon rat, shows partial amino acid sequence similarity with the LST7 product of Saccharomyces cerevisiae in amino-terminal half. Yeast mutants of LST7 gene have been reported to show defects in membrane transport system. We found that LST7-disruptant yeasts were slightly more sensitive to rapamycin than wild-type yeasts. However no apparent difference was observed in degree of resistance against toxic amino acid analogues tested so far. Introduction of rat wild-type or carboxy-terminally truncated folliculin-expression plasmids into mutant yeasts did not restore normal rapamycin sensitivity. We are analyzing other phenotypes of LST7 mutant and effect of mammalian folliculin expression in m … More utant yeasts. For analyze folliculin function using mammalian cells, we established and analyzed Bhd deficient renal tumor cell lines (1B series) in which rat Bhd cDNA was expressed by using the tet-off system. Compared with control cells (1R series) introduced with empty vector, 1B cells exhibited no apparent growth suppression. Expression of transpoters such as Gluts did not significantly change. However, 1B and 1R cells showed different morphological phenotypes. At phase-contrast microscopic level, cell adhesion and spreading were differ each other. By co-immunoprecipitation assay, we preliminarily found that the non-muscle myosin was co-precipitated using anti-Bhd antibody in 1B cell-specific manner. One plausible hypothesis is that Bhd products regulates cytoskeletal components as well as membrane transport systems. Through such functions, Bhd may modulates nutrient- or energy-regulated signal transuduction. We will clarify the function of Bhd product and its relation with nutrient/energy-regulated signals as well as Tsc2 product. Less