Factor of suppression of tissue protein degradation after feeding and its mechanism

饲后组织蛋白降解抑制因素及其机制

• 批准号: 09660126
• 负责人: NAGASAWA Takashi
• 金额: $ 2.11万
• 依托单位: IWATE UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09660126/
• 关键词: Dietary protein; Myofibrillar protein; Protein degradation; Protein synthesis; Leucine; 3-Methylhistidine; p70S6 kinase; 必須アミノ酸; ロイジン; キビ; ユビキチン; リソソーム

After feeding of 20% casein diet for 1h, the rate of myofibrillar protein degradation measured by the serum concentration of 3-methyl-histidine (MeHis) and the release rate of MeHis from the isolated muscle significantly decreased, although they did not change when rats fed protein free diet. The suppression was increased with content of dietary protein content and it was not changed when feeding protein content was constant but energy was decreased. These results strongly suggest that dietary protein directly regulate myofibrillar protein degradation after feeding. Leu in dietary protein mainly affect the suppression, since these change was also seen in rats fed on Leu diet or force fed on Leu suspension.Mechanism of suppression of degradation after feeding was analyzed by proteolysis inhibitors. When lysosome and calcium-dependent proteolytic systems were inhibited, the suppression was not seen, indicating that calpain may key enzyme. However, when ATP-dependent proteolytic system was inhibited, the suppression of myofibrillar protein degradation after feeding was demonstrated.Phosphorylation of p70S6 kinase which correlates with protein synthesis was immediately activated by protein and Leu feeding. Therefore, protein synthesis may be activated more rapidly than protein degradation by feeding.

饲喂20%酪蛋白日粮1h后，以血清3-甲基组氨酸（3-methyl-histidine, MeHis）浓度测定的肌原纤维蛋白降解率和离体肌肉中MeHis的释放率均显著降低，但饲喂无蛋白日粮时无明显变化。随着饲粮蛋白质含量的增加，抑制作用逐渐增强，当饲粮蛋白质含量一定时，抑制作用不发生变化。这些结果强烈提示饲粮蛋白质直接调节饲喂后肌原纤维蛋白的降解。膳食蛋白质中的亮氨酸主要影响抑制，因为在饲喂亮氨酸日粮或强制饲喂亮氨酸悬浮液的大鼠中也看到了这些变化。分析了蛋白水解抑制剂抑制饲喂后降解的机理。当溶酶体和钙依赖性蛋白水解系统被抑制时，未见抑制，表明钙蛋白酶可能是关键酶。然而，当atp依赖的蛋白水解系统被抑制时，饲喂后肌原纤维蛋白降解被抑制。蛋白质和亮氨酸的摄食立即激活了与蛋白质合成相关的p70S6激酶的磷酸化。因此，通过摄食激活蛋白质合成可能比蛋白质降解更快。

项目成果

Yoshizawa, F., Kido, T., and Nagasawa, T.: Biosci. Biotechnol. Biochem.. 63. 1803-1805 (1999)

吉泽 F.、木户 T. 和长泽 T.：Biosci。

Takashi Nagasawa 他: "Myofibrillar protein catabolism is rapidly suppressed following protein feeding" Biosci.Biotechnol.Biochem.62(10). 1932-1937 (1998)

Takashi Nagasawa 等人：“肌原纤维蛋白分解代谢在蛋白质喂养后迅速受到抑制”Biosci.Biotechnol.Biochem.62(10) 1932-1937 (1998)。

Nagasawa, T., Hirano, J., and Nishizawa, N.: Rep. Res. Comm. Essential Amino Acids (Japan). 151. 4-9 (1998)

Nagasawa, T.、Hirano, J. 和 Nishizawa, N.：Rep. Res。

長澤孝志, 平野順子, 西澤直行: "ラットにおける摂食後の筋肉タンパク質の分解" 必須アミノ酸研究. 148. 11-16 (1997)

Takashi Nagasawa、Junko Hirano、Naoyuki Nishizawa：“喂食大鼠后肌肉蛋白的降解”必需氨基酸研究。148. 11-16 (1997)。

Yoshizawa F.,Kido T.,and Nagasawa T.: "Stimulative effect of dietary protein on the phosphorylation of p70 S6 kinase in the skeletal muscle and liver of food-deprived rats"Biosci. Biotechnol. Biochem.. 63. 1803-1805 (1999)

Yoshizawa F.、Kido T. 和 Nagasawa T.：“膳食蛋白质对食物剥夺大鼠骨骼肌和肝脏中 p70 S6 激酶磷酸化的刺激作用”Biosci。