Ketone body metabolites in intestinal stem cell homeostasis and disease.

肠道干细胞稳态和疾病中的酮体代谢。

• 批准号: 10313437
• 负责人: Jessica Elizabeth Stewart Shay
• 金额: $ 7.49万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-01-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10313437
• 关键词: Ketone; body; metabolites; intestinal; stem

Project Summary/Abstract Diet has a profound impact on organismal health. Fasting improves human health in part by reducing inflammation, decreasing oxidative damage and extending longevity, however, the mechanisms by which fasting improves intestinal regeneration remains poorly understood. The intestinal epithelium renews fastidiously every 5-7 days via Leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5+) expressing intestinal stem cells (ISCs) found at the base of the intestinal crypt. LGR5+ ISCs balance differentiation and epithelial cell divisions to influence tissue regeneration by integrating metabolic and signaling cues from their environment like diet. Fasting has a profound effect on ISC function in young and aged mice and can improve the age-associated decline in tissue regeneration through the induction of fatty acid oxidation (FAO), a process that oxidizes fatty acids into acetyl-CoA units. In addition, LGR5+ ISCs strongly express 3-hydroxy-3-methylglutaryl-CoA synthetase 2 (HMGCS2), the rate-limiting enzyme in the ketogenic pathway whereby acetyl-CoA units are converted to ketone bodies such as beta-hydroxybutyrate (bOHB) and acetoacetate (AcAc). Mechanistically, bOHB reinforces the NOTCH signaling pathway by inhibiting class I histone-deacetylases (HDACs) to instruct ISC cell fate decisions. These findings further support a nuanced relationship between host nutritional state and stem cell function whereby dynamic control of ISC bOHB levels enable their rapid adaptation to diverse physiological states such as fasting. Other roles for ISC-derived ketone body metabolites have yet to be elucidated and, as such, we propose that bOHB and AcAc function as distinct signaling metabolites regulating ISC fasting responses (Aim 1) and have unique roles as energetic substrates (Aim 2). To test this hypothesis, we will use key genetic mouse models to understand how perturbed bOHB/AcAc ratios alter intestinal stem cell function in vivo and in vitro (Aim 1), as well as labelled substrate administration and novel techniques for rapid mitochondrial isolation to determine key ISC metabolic adaptations to fasting (Aim 2). Taken together, the experiments proposed will mechanistically delineate the signaling and energetic roles of ketone body metabolites on intestinal stemness and improve our understanding of how the fasting response via ketone bodies influences intestinal regeneration. We expect this approach will identify therapeutic options exploiting ketone bodies and the signaling and energetic pathways engaged by them to enhance intestinal regeneration in cases of injury and age-related decline of stem cell function.

项目概要/摘要 饮食对机体健康有着深远的影响。禁食改善人类健康的部分原因是减少 炎症、减少氧化损伤和延长寿命，然而，禁食的机制 改善肠道再生仍知之甚少。肠上皮细胞每 通过富含亮氨酸重复序列的 G 蛋白偶联受体 5 (LGR5+) 表达肠干 5-7 天 肠隐窝底部发现的细胞（ISC）。 LGR5+ ISC 平衡分化和上皮细胞 通过整合来自环境的代谢和信号线索来影响组织再生的分裂 饮食。禁食对年轻和老年小鼠的 ISC 功能具有深远影响，并且可以改善与年龄相关的 通过诱导脂肪酸氧化（FAO）（氧化脂肪的过程）而导致组织再生下降 酸转化为乙酰辅酶A单元。此外，LGR5+ ISC 强烈表达 3-羟基-3-甲基戊二酰辅酶 A 合成酶 2 (HMGCS2)，生酮途径中的限速酶，通过乙酰辅酶 A 单位 转化为酮体，例如 β-羟基丁酸 (bOHB) 和乙酰乙酸 (AcAc)。从机械上来说， bOHB 通过抑制 I 类组蛋白脱乙酰酶 (HDAC) 来增强 NOTCH 信号通路，以指示 ISC细胞命运决定。这些发现进一步支持宿主营养状态与宿主之间的微妙关系。 干细胞功能，动态控制 ISC bOHB 水平使其能够快速适应不同的环境 生理状态，例如禁食。 ISC 衍生的酮体代谢物的其他作用尚未确定 已阐明，因此，我们提出 bOHB 和 AcAc 作为不同的信号代谢物调节 ISC 禁食反应（目标 1）并作为能量底物具有独特的作用（目标 2）。为了检验这个假设， 我们将使用关键的遗传小鼠模型来了解扰动的 bOHB/AcAc 比率如何改变肠道干细胞 体内和体外功能（目标 1），以及标记底物施用和快速快速检测的新技术 线粒体分离以确定 ISC 对禁食的关键代谢适应（目标 2）。综合起来， 提出的实验将机械地描述酮体代谢物的信号传导和能量作用 肠道干性并提高我们对禁食反应如何通过酮体影响的理解 肠道再生。我们预计这种方法将确定利用酮体和 它们参与的信号传导和能量途径可在受伤时增强肠道再生， 与年龄相关的干细胞功能衰退。