Department of Nutrition Science, Purdue University, West Lafayette, IN, 47907, USA.
Purdue Proteomics Facility, Bindley Bioscience Center, Purdue University, West Lafayette, IN, 47907, USA; Department of Comparative Pathobiology, Purdue University, West Lafayette, IN, 47907, USA.
Biochem Biophys Res Commun. 2022 Nov 12;629:40-46. doi: 10.1016/j.bbrc.2022.08.070. Epub 2022 Sep 3.
Obesity is associated with a spectrum of nonalcoholic fatty liver disease (NAFLD) which is characterized by steatosis. Prolonged fat deposition aggravates liver dysfunctions leading to an advanced form of NAFLD such as steatohepatitis and cirrhosis. As liver function in the postprandial state is critical for macronutrient metabolism and energy homeostasis, we sought to determine the differences in protein complex profiles in lean and fatty livers in the postprandial state. Protein complex profiling is of interest as proteins often do not function alone and the information on the interactions may reveal novel etiology of NAFLD, which is currently limited compared with proteome profiles or RNA-sequencing profiles. To this end, we fractionated liver lysates using size-exclusion chromatography (SEC) and analyzed each fraction using untargeted LC-MS/MS. We identified 1172 proteins that were discovered in lean and fatty livers, and their elution profiles were compared. We found that the majority of liver proteins were present as putative complexes. Also, the fatty liver protein elution profile showed great conservations as lean liver despite the metabolic disease state. Yet, we discovered a few proteins that showed different elution patterns in the fatty liver, including Acadm, Aldh1a7, Aldh1a1, Akr1a1, Eif3l, Fkbp2, G6pdx, Gm20441, Hao1, Pcna, Pkm, Ppif, Prdx4, Stmn1, Tagln, Tubb4b, Ubqln2, and Usp14, which may be involved in high fat diet-induced alterations of protein oligomerization and hepatic functions. Overall, our protein complex profiling could expand our understanding of hepatic abnormalities that cannot be uncovered by simple quantitation of protein expression.
肥胖与非酒精性脂肪性肝病（NAFLD）谱相关，其特征为脂肪变性。脂肪沉积时间延长会加重肝功能异常，导致非酒精性脂肪性肝病的进展形式，如脂肪性肝炎和肝硬化。由于餐后状态下的肝功能对宏量营养素代谢和能量稳态至关重要，我们试图确定在餐后状态下，瘦肝和脂肪肝中的蛋白质复合物谱的差异。蛋白质复合物谱的研究很有意义，因为蛋白质通常不是单独起作用的，关于相互作用的信息可能揭示非酒精性脂肪性肝病的新病因，与蛋白质组谱或 RNA 测序谱相比，目前这方面的信息有限。为此，我们使用尺寸排阻色谱（SEC）对肝裂解物进行分级，并使用非靶向 LC-MS/MS 分析每个级分。我们鉴定了在瘦肝和脂肪肝中发现的 1172 种蛋白质，并比较了它们的洗脱曲线。我们发现，大多数肝蛋白以假定复合物的形式存在。此外，尽管存在代谢性疾病状态，但脂肪肝的蛋白质洗脱曲线与瘦肝非常相似。然而，我们发现了一些在脂肪肝中显示出不同洗脱模式的蛋白质，包括 Acadm、Aldh1a7、Aldh1a1、Akr1a1、Eif3l、Fkbp2、G6pdx、Gm20441、Hao1、Pcna、Pkm、Ppif、Prdx4、Stmn1、Tagln、Tubb4b、Ubqln2 和 Usp14，它们可能参与高脂肪饮食诱导的蛋白质寡聚化和肝功能改变。总的来说，我们的蛋白质复合物谱分析可以扩展我们对肝脏异常的理解，这些异常不能通过简单的蛋白质表达定量来揭示。
