PDF(Pubmed)
Abstract：
The pathogenesis of non-alcoholic fatty liver disease (NAFLD) is influenced by a number of variables, including endoplasmic reticulum stress (ER). Thioredoxin domain-containing 5 (TXNDC5) is a member of the protein disulfide isomerase family and acts as an endoplasmic reticulum (ER) chaperone. Nevertheless, the function of TXNDC5 in hepatocytes under ER stress remains largely uncharacterized. In order to identify the role of TXNDC5 in hepatic wild-type (WT) and TXNDC5-deficient (KO) AML12 cell lines, tunicamycin, palmitic acid, and thapsigargin were employed as stressors. Cell viability, mRNA, protein levels, and mRNA splicing were then assayed. The protein expression results of prominent ER stress markers indicated that the ERN1 and EIF2AK3 proteins were downregulated, while the HSPA5 protein was upregulated. Furthermore, the ATF6 protein demonstrated no significant alterations in the absence of TXNDC5 at the protein level. The knockout of TXNDC5 has been demonstrated to increase cellular ROS production and its activity is required to maintain normal mitochondrial function during tunicamycin-induced ER stress. Tunicamycin has been observed to disrupt the protein levels of HSPA5, ERN1, and EIF2AK3 in TXNDC5-deficient cells. However, palmitic acid has been observed to disrupt the protein levels of ATF6, HSPA5, and EIF2AK3. In conclusion, TXNDC5 can selectively activate distinct ER stress pathways via HSPA5, contingent on the origin of ER stress. Conversely, the absence of TXNDC5 can disrupt the EIF2AK3 cascade.
摘要：
非酒精性脂肪性肝病（NAFLD）的发病机制受许多变量的影响，包括内质网应激(ER)。含有硫氧还蛋白结构域5（TXNDC5）是蛋白质二硫键异构酶家族的成员，并充当内质网（ER）伴侣。然而，在内质网应激下,TXNDC5在肝细胞中的功能仍未表征.为了确定TXNDC5在肝野生型（WT）和TXNDC5缺陷（KO）AML12细胞系中的作用，衣霉素,棕榈酸,thapsigargin被用作压力源。细胞活力，mRNA蛋白质水平，然后测定mRNA剪接。突出的内质网应激标志物的蛋白表达结果表明，ERN1和EIF2AK3蛋白表达下调，而HSPA5蛋白上调。此外，在蛋白质水平上,在不存在TXNDC5的情况下,ATF6蛋白没有表现出显著的改变。TXNDC5的敲除已被证明可增加细胞ROS的产生，并且其活性是在衣霉素诱导的ER应激期间维持正常线粒体功能所必需的。已观察到衣霉素破坏TXNDC5缺陷细胞中HSPA5，ERN1和EIF2AK3的蛋白质水平。然而,已观察到棕榈酸破坏ATF6、HSPA5和EIF2AK3的蛋白质水平。总之,TXNDC5可以通过HSPA5选择性激活不同的ER应激途径，这取决于ER应激的起源。相反，TXNDC5的缺失可以破坏EIF2AK3级联。
