Endoplasmic Reticulum Stress-Mediated Autophagy and Apoptosis Alleviate Dietary Fat-Induced Triglyceride Accumulation in the Intestine and in Isolated Intestinal Epithelial Cells of Yellow Catfish
Endoplasmic Reticulum Stress-Mediated Autophagy and Apoptosis Alleviate Dietary Fat-Induced Triglyceride Accumulation in the Intestine and in Isolated Intestinal Epithelial Cells of Yellow Catfish
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DOI：
10.1093/jn/nxz135
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发表时间：
2019-10-01
影响因子：
4.2
通讯作者：
Luo, Zhi
中科院分区：
文献类型：
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作者：
Ling, Shi-Cheng;Wu, Kun;Luo, Zhi
背景：肠道是吸收膳食脂肪的主要器官。高脂饮食摄入导致脂肪在肠道沉积，并对脂肪吸收和健康产生不利影响，但其潜在机制尚不清楚。目的：利用黄颡鱼及其离体肠上皮细胞，验证内质网应激、自噬和细胞凋亡介导脂肪诱导的脂质代谢变化的假说。方法：将体重为3.79±0.16 g、年龄为3月龄的公母黄颡鱼分别饲喂脂肪含量为6.98%（低脂饲料）、11.3%（中脂饲料）和15.4%（高脂饲料）（按体重计）的饲料，饲养8周。每个饲粮组设3个重复，每个重复30尾鱼。分离小鼠肠上皮细胞，在对照溶液或不同浓度的脂肪酸（FAs）中孵育24小时，并使用或不使用抑制剂[3-甲基腺嘌呤（3MA）、4-苯基丁酸（4-PBA）或AC - dved - cho (AC)]预处理2小时。测定肠组织和细胞中甘油三酯（TG）含量、参与脂质代谢、内质网应激、自噬和凋亡的基因和酶；对肠细胞进行免疫印迹、BODIPY 493/503染色、超微结构观察、自噬和凋亡小泡检测。结果：与LFD和mfd相比，HFD使肠道TG含量提高120 ~ 226%，脂肪生成酶活性提高19.0 ~ 245%，脂肪生成（0.77 ~ 8.4倍）、脂肪分解（0.36 ~ 6.0倍）、FA转运蛋白（0.79 ~ 1.7倍）、内质酸应激（0.55 ~ 7.5倍）、自噬（0.56 ~ 4.2倍）和细胞凋亡（0.80 ~ 5.2倍）相关基因表达增加。使用分离的肠上皮细胞和抑制剂（4-PBA、3-MA和AC），我们发现内质酰胺应激介导fa诱导的自噬（11.0-50.1%）和凋亡（10.4-32.0%）激活，脂噬和凋亡介导fa诱导的脂解（3.4041.6%）。结论：HFD上调脂肪生成、脂肪分解和FA转运，诱导内质网应激，激活自噬和细胞凋亡。内质网应激、自噬和细胞凋亡在黄颡鱼肠道及肠上皮细胞脂质代谢变化中起重要调节作用。
Background: The intestine is the main organ for absorbing dietary fat. High dietary lipid intake leads to fat deposition in the intestine and adversely influences fat absorption and health, but the underlying mechanism is unknown.Objectives: We used yellow catfish and their isolated intestinal epithelial cells to test the hypothesis that endoplasmic reticulum (ER) stress, autophagy, and apoptosis mediate fat-induced changes in lipid metabolism.Methods: Male and female yellow catfish (weight: 3.79 +/- 0.16 g; age: 3 mo) were fed diets containing lipid at 6.98% (low-fat diet; LFD), 11.3%(middle-fat diet; MFD), or 15.4% (high-fat diet; HFD) (byweight) for 8wk. Each dietary group had 3 replicates, 30 fish per replicate. Their intestinal epithelial cells were isolated and incubated for 24 h in control solution or various concentrations of fatty acids (FAs) with or without 2-h pretreatment with an inhibitor [3-methyladenine (3MA), 4-phenyl butyric acid (4-PBA), or Ac-DVED-CHO (AC)]. Triglyceride (TG) contents, genes, and enzymes involved in lipid metabolism, ER stress, autophagy, and apoptosis were determined in intestinal tissue and cells; immunoblotting, BODIPY 493/503 staining, ultrastructural observation, and the detection of autophagic and apoptotic vesicles were performed on intestinal cells.Results: Compared with the LFD andMFD, the HFD increased intestinal TG content by 120-226%, activities of lipogenic enzymes by 19.0-245%, expression of genes related to lipogenesis (0.77-8.4-fold), lipolysis (0.36-6.0-fold), FA transport proteins (0.79-1.7-fold), ER stress (0.55-7.5-fold), autophagy (0.56-4.2-fold), and apoptosis (0.80-5.2-fold). Using isolated intestinal epithelial cells and inhibitors (4-PBA, 3-MA, and AC), we found that ER stress mediated FA-induced activation of autophagy (11.0-50.1%) and apoptosis (10.4-32.0%), and lipophagy and apoptosis mediated FA-induced lipolysis (3.4041.6%).Conclusions: An HFD upregulated lipogenesis, lipolysis, and FA transport, induced ER stress, and activated autophagy and apoptosis. ER stress, autophagy, and apoptosis play important regulatory roles in fat-induced changes in lipid metabolism in the intestine and intestinal epithelial cells of yellow catfish.