Regulation of the expression of microvillar lactase in small intestine

小肠微绒毛乳糖酶表达的调节

• 批准号: 05670071
• 负责人: GODA Toshinao
• 金额: $ 1.22万
• 依托单位: University of Shizuoka
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1993
• 资助国家: 日本
• 起止时间: 1993 至 1994
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05670071/
• 关键词: Lactase; Sucrase; mRNA; Microvillar Membrane; Carbohydrate; Lipid; Diurnal Rhythm; Intestinal Villus; 小腸; 微縅毛膜; 小腸縅毛; 胆汁酸

Regulatory mechanisms of lactase expression were investigated.1.Gene expression of lactase along the villus-crypt axis :Dot blot hybridization of lactase mRNA extracted from six consecutive fractions of villus-crypt columns revealed that, unlike sucrase mRNA which was expressed maximally in the lower villus, maximal lactase mRNA level was not attained until the upper villus, suggesting that lactase gene is continuously expressed in the differentiating as well as in the mature absorptive cells.2.Dietary regulation of lactase gene expression :A short-term force-feeding experiment showed that sucrese evoked lactase mRNA levels, but a non-metabolizable sugar (alpha-methylglucoside) was unable to enhance it.The sucrose-induced increase in lactase mRNA levels was observed along the entire height of villi, and this enhancement was completely inhibited by actinomycin D injection, suggesting that lactase gene transcription might be enhanced by metabolite (s) of carbohydrates.3.Localization of l … More actase in enterocytes :Immunoelectron microscopy revealed that lactase was detected not only in the microvilli, but also in the lateral membranes, suggesting that an alternative route for intracellular transport of lactase via the lateral membranes to the microvilli.4.Diet-induced changes in posttranslational modifications of lactase :Feeding medium-chain triglycerides (MCT) causes a decrease in bile acid concentrations in the intestinal lumen, resulting in a retarded degradation of sucrase in the microvilli.The animals fed the high long-chain triglyceride (LCT) diet showed a lower lactase activity than the rats fed the high-MCT diet, which was accompanied by the reduction in the lactase activity per unit weight of immunoreactive lactase, suggesting that LCT might accelerate inactivation and/or degradation of lactase.5.Diurnal rhythm of lactase expression :Sucrase mRNA exhibited diurnal variations, but lactase mRNA did not show diurnal variations.Total lactase activity in the microvillar membranes showed a diurnal variation together with a parallel variation of total microvillar proteins, suggesting that diurnal rhythm of lactase activity is caused by a change in turnover of microvillar proteins. Less

研究乳糖酶表达的调控机制。绒毛-隐窝轴上乳糖酶基因的表达：对绒毛-隐窝柱连续6段提取的乳糖酶mRNA进行Dot blot杂交发现，与蔗糖酶mRNA在绒毛下部表达最多不同，乳糖酶mRNA在绒毛上部表达最多，表明乳糖酶基因在分化细胞和成熟吸收细胞中持续表达。饲粮对乳糖酶基因表达的调节：一项短期强迫喂养实验表明，蔗糖可诱发乳糖酶mRNA水平，但非代谢糖（α -甲基葡萄糖苷）无法提高乳糖酶mRNA水平。在整个绒毛高度观察到蔗糖诱导的乳糖酶mRNA水平升高，而放线菌素D完全抑制了这种升高，表明糖的代谢产物可能增强了乳糖酶基因的转录。免疫电镜显示，不仅在微绒毛中检测到乳糖酶，而且在侧膜中也检测到乳糖酶，这表明乳糖酶通过侧膜到微绒毛的胞内转运途径有另一种。饮食诱导的乳糖酶翻译后修饰的变化：喂养中链甘油三酯（MCT）导致肠腔内胆汁酸浓度下降，导致微绒毛中蔗糖酶降解迟缓。饲喂高长链甘油三酯（LCT）饲料的动物的乳糖酶活性低于饲喂高mct饲料的大鼠，这伴随着单位重量免疫反应性乳糖酶活性的降低，表明LCT可能加速了乳糖酶的失活和/或降解。乳糖酶表达的日节律：蔗糖酶mRNA有日变化，但乳糖酶mRNA无日变化。微绒毛膜内总乳糖酶活性与总微绒毛蛋白呈平行日变化，表明乳糖酶活性的日节律是由微绒毛蛋白周转量的变化引起的。少

项目成果

Goda,T.and Takase,S.: "Dietary carbohydrate and fat independently modulate disaccharidase activities in rat jejunum." Journal of Nutrition. 124. 2233-2239 (1994)

Goda,T. 和 Takase,S.：“膳食碳水化合物和脂肪独立调节大鼠空肠中的二糖酶活性。”

合田敏尚: "小腸刷子緑の機能的構築と糖質の消化・吸収" 臨床科学. 29. 981-988 (1993)

Toshihisa Goda：“小肠刷绿的功能结构与碳水化合物的消化和吸收”临床科学29。981-988（1993）。

Goda,T.and Takase,S.: "Dietary carbohydrate and fat independently modulate disaccharidase activities in rat jejunum." Journal of Nutrition. (in press). (1994)

Goda,T. 和 Takase,S.：“膳食碳水化合物和脂肪独立调节大鼠空肠中的二糖酶活性。”

合田,敏尚: "小腸二糖類水解酵素の食事要因による調節機構" 日本栄養・食糧学会誌. 47. 81-92 (1994)

Goda, Toshihisa：“饮食因素对小肠二糖水解酶的调节机制”，日本营养食品学会杂志 47. 81-92 (1994)。

Yasutake, H.et al.: "Dietary regulation of sucrase-isomaltase gene expression in rat jejunum." Biochimica et Biophysica Acta. 1243. 270-276 (1995)

Yasutake, H.et al.：“大鼠空肠中蔗糖酶-异麦芽糖酶基因表达的饮食调节。”