非酒精性脂肪性肝病或脂肪变性是肝脏中脂肪的积累。非酯化脂肪酸的含量增加,缺钙,或胰岛素抵抗可能会干扰内质网(ER)稳态,导致错误折叠蛋白质的异常积累,激活未折叠的蛋白质反应。ER是伴侣如含硫氧还蛋白结构域5(TXNDC5)的主要定位位点。谷胱甘肽参与细胞氧化应激,它与内质网中TXNDC5的相互作用可能会降低该蛋白的二硫键。此外,谷胱甘肽过氧化物酶利用谷胱甘肽灭活氧化脂质。为了表征与TXNDC5相互作用的蛋白质,使用了免疫沉淀和液相色谱-质谱。脂质过氧化,还原型谷胱甘肽,在缺乏AML12和TXNDC5的AML12细胞系中评估了诱导型磷脂酶A2(iPLA2)和肝转录组。成果显示HSPA9和PRDX6在AML12细胞中与TXNDC5互相感化。此外,TXNDC5缺乏降低了AML12中PRDX6和HSPA9的蛋白质水平。此外,脂质过氧化,谷胱甘肽和iPLA2活性在TXNDC5缺陷细胞中显著降低,并找出PRDX6蛋白减少的原因,蛋白酶体抑制显示对它没有相当大的影响。最后,与PRDX6和HSPA9连接的肝转录本表明Dnaja3,Mfn2和Prdx5增加,Npm1,Oplah减少,Gstp3,Gstm6,Gstt1,Serpina1a,Serpina1b,Serpina3m,AML12KO细胞中Hsp90aa1和Rps14mRNA水平。总之,缺乏TXNDC5可能会破坏AML12细胞中的脂质过氧化系统和谷胱甘肽机制,TXNDC5是PRDX6和HSPA9的新型蛋白质-蛋白质相互作用伴侣。
Non-alcoholic fatty liver disease or steatosis is an accumulation of fat in the liver. Increased amounts of non-esterified fatty acids, calcium deficiency, or insulin resistance may disturb endoplasmic reticulum (ER) homeostasis, which leads to the abnormal accumulation of misfolded proteins, activating the unfolded protein response. The ER is the primary location site for chaperones like thioredoxin domain-containing 5 (TXNDC5). Glutathione participates in cellular oxidative stress, and its interaction with TXNDC5 in the ER may decrease the disulfide bonds of this protein. In addition, glutathione is utilized by glutathione peroxidases to inactivate oxidized lipids. To characterize proteins interacting with TXNDC5, immunoprecipitation and liquid chromatography-mass spectrometry were used. Lipid peroxidation, reduced glutathione, inducible phospholipase A2 (iPLA2) and hepatic transcriptome were assessed in the AML12 and TXNDC5-deficient AML12 cell lines. The results showed that
HSPA9 and PRDX6 interact with TXNDC5 in AML12 cells. In addition, TXNDC5 deficiency reduced the protein levels of PRDX6 and
HSPA9 in AML12. Moreover, lipid peroxidation, glutathione and iPLA2 activities were significantly decreased in TXNDC5-deficient cells, and to find the cause of the PRDX6 protein reduction, proteasome suppression revealed no considerable effect on it. Finally, hepatic transcripts connected to PRDX6 and
HSPA9 indicated an increase in the Dnaja3, Mfn2 and Prdx5 and a decrease in Npm1, Oplah, Gstp3, Gstm6, Gstt1, Serpina1a, Serpina1b, Serpina3m, Hsp90aa1 and Rps14 mRNA levels in AML12 KO cells. In conclusion, the lipid peroxidation system and glutathione mechanism in AML12 cells may be disrupted by the absence of TXNDC5, a novel protein-protein interacting partner of PRDX6 and
HSPA9.