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Regulation Mechanism of Glycolysis in Skeletal Muscle

骨骼肌糖酵解的调节机制

基本信息

批准号：
12680641
负责人：
WATANABE Fusao
金额：
$ 1.66万
依托单位：
Osaka Medical College
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

Tissue-specific expression pattern of fructose-6-phosphate 2-kinase/fructose 2,6-bisphosphatase (F6P2K) was studied to elucidate a regulation mechanism of glycolysis in skeletal muscle. The F6P2K catalyzes the synthesis and degradation of fructose 2,6-bisphosphate (F26P) which is the most potent activator of glycolysis. The ratio of these activities of the enzyme determines the intracellular content of F26P. Four tissue-specific isozyme genes of the enzyme have been identified in liver, heart, testis and brain. Recently, we have found that the genes produce at least fifteen mRNAs by alternative splicing in a tissue-specific manner. The variety of the enzyme is very important for tissue-specific regulation of glycolysis. In this study we demonstrate the occurrence of nine mRNAs, namely, RM2K, RH2K1, RH2K4, RB2K2, RB2K3, RB2K5, RB2K6, RB2K7 and RB2K8. It is already known that the RM2K is expressed as a protein in skeletal muscle. However, the isoform cannot regulate the glycolysis because it catalyzes the degradation but not the synthesis. Therefore, we prepared antibodies using oligopeptides as antigens to detect each isoform by western blot. Surprisingly, no isoform was detected in skeletal muscle. Interestingly, the RB2K7 isoform was detected only in heart, although the RB2K7 and the RB2K8 mRNAs were expressed in brain, skeletal muscle and heart at the same level. These results indicate that the expression of the RB2K7 and RB2K8 proteins is regulated by translational and/or post-translational processes but not by their mRNA levels.

为阐明骨骼肌糖酵解的调控机制，研究了果糖-6-磷酸2-激酶/果糖2，6-二磷酸酶（F6 P2 K）的组织特异性表达模式。F6 P2 K催化果糖2，6-二磷酸（F26 P）的合成和降解，果糖2，6-二磷酸是糖酵解的最有效的活化剂。酶的这些活性的比率决定了F26 P的细胞内含量。该酶的四种组织特异性同工酶基因已在肝脏、心脏、睾丸和脑中被鉴定。最近，我们发现这些基因以组织特异性方式通过选择性剪接产生至少15种mRNA。糖酵解酶的多样性对糖酵解的组织特异性调节非常重要。在这项研究中，我们证明了9种mRNA的存在，即RM 2K，RH 2K 1，RH 2K 4，RB 2K 2，RB 2K 3，RB 2K 5，RB 2K 6，RB 2K 7和RB 2K 8。已知RM 2K在骨骼肌中表达为蛋白质。然而，异构体不能调节糖酵解，因为它催化降解而不是合成。因此，我们使用寡肽作为抗原制备抗体以通过蛋白质印迹检测每种亚型。令人惊讶的是，在骨骼肌中未检测到同种型。有趣的是，RB 2K 7亚型仅在心脏中检测到，尽管RB 2K 7和RB 2K 8 mRNA在脑、骨骼肌和心脏中以相同水平表达。这些结果表明RB 2K 7和RB 2K 8蛋白的表达受翻译和/或翻译后过程的调节，但不受其mRNA水平的调节。