Morphological, biochemical, transcriptional and epigenetic responses to fasting and refeeding in intestine of Xenopus laevis.
Morphological, biochemical, transcriptional and epigenetic responses to fasting and refeeding in intestine of Xenopus laevis.
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DOI：
10.1186/s13578-016-0067-9
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发表时间：
2016
影响因子：
7.5
通讯作者：
Yamauchi K
中科院分区：
文献类型：
--
作者：
Tamaoki K;Okada R;Ishihara A;Shiojiri N;Mochizuki K;Goda T;Yamauchi K
两栖动物可以在没有食物的情况下生存几个月。然而，目前尚不清楚它们生存的分子机制是什么。为了表征肠道对禁食和重新进食的反应，我们研究了成年雄性非洲爪蟾肠道的形态、生化、转录和表观遗传变化。青蛙喂食 22 天，禁食 22 天，或禁食 21 天，补食 1 天。禁食减少，再进食部分或完全恢复形态参数（肠道湿重、上皮层周长和绒毛谷单位中的谷数）、消化酶活性和血浆生化参数（葡萄糖、甘油三酯、胆固醇和游离脂肪酸）。逆转录定量聚合酶链反应分析揭示了禁食对转录水平的总体抑制，重新进食时的恢复率各不相同。对转录水平随禁食而下降并在重新进食后迅速恢复的选定基因进行染色质免疫沉淀分析，显示禁食时组蛋白（乙酰化和甲基化）和 RNA 聚合酶 II 修饰（磷酸化）中存在一些常染色质标记，并通过重新进食恢复到进食水平。这些基因的 mRNA 水平对禁食和再进食的反应程度比前 mRNA 水平更大，表明转录后调控的参与。我们的结果表明，滑鼠肠道可能至少在转录水平上经历整体代谢抑制，以在禁食期间节省能量，并通过重新进食迅速恢复到中度营养缺乏，并表明肠道的这些饮食反应是表观遗传和转录后调节的。本文的在线版本 (doi:10.1186/s13578-016-0067-9) 包含补充材料，可供授权用户使用。
Amphibians are able to survive for several months without food. However, it is unclear what molecular mechanisms underlie their survival. To characterize the intestinal responses to fasting and refeeding, we investigated morphological, biochemical, transcriptional and epigenetic changes in the intestine from adult male Xenopus laevis. Frogs were fed for 22 days, fasted for 22 days, or fasted for 21 days and refed for 1 day. Fasting reduced, and refeeding recovered partially or fully, morphological parameters (wet weight of the intestine, circumference of the epithelial layer and number of troughs in a villus-trough unit), activities of digestive enzymes and plasma biochemical parameters (glucose, triglycerides, cholesterol and free fatty acids). Reverse transcription-quantitative polymerase chain reaction analysis revealed overall suppression of the transcript levels by fasting, with various recovery rates on refeeding. Chromatin immunoprecipitation assays on the selected genes whose transcript levels declined with fasting and recovered quickly with refeeding, showed several euchromatin marks in histone (acetylation and methylation) and RNA polymerase II modifications (phosphorylation) with fasting, and returned to the feeding levels by refeeding. The mRNA levels of these genes responded to fasting and refeeding to greater extents than did the pre-mRNA levels, suggesting the involvement of post-transcriptional regulation. Our results demonstrate that the X. laevis intestine may undergo overall metabolic suppression at least at the transcriptional level to save energy during fasting and quickly recovered to moderate nutritional deficiency by refeeding, and suggest that these dietary responses of the intestine are epigenetically and post-transcriptionally regulated. The online version of this article (doi:10.1186/s13578-016-0067-9) contains supplementary material, which is available to authorized users.