Temporal Proteomic Analysis of Pancreatic β-Cells in Response to Lipotoxicity and Glucolipotoxicity

Abstract

Chronic hyperlipidemia causes the dysfunction of pancreatic β-cells, such as apoptosis and impaired insulin secretion, which are aggravated in the presence of hyperglycemia. The underlying mechanisms, such as endoplasmic reticulum (ER) stress, oxidative stress and metabolic disorders, have been reported before; however, the time sequence of these molecular events is not fully understood. Here, using isobaric labeling-based mass spectrometry, we investigated the dynamic proteomes of INS-1 cells exposed to high palmitate in the absence and presence of high glucose. Using bioinformatics analysis of differentially expressed proteins, including the time-course expression pattern, protein-protein interaction, gene set enrichment and KEGG pathway analysis, we analyzed the dynamic features of previously reported and newly identified lipotoxicity- and glucolipotoxicity-related molecular events in more detail. Our temporal data highlight cholesterol metabolism occurring at 4 h, earlier than fatty acid metabolism that started at 8 h and likely acting as an early toxic event highly associated with ER stress induced by palmitate. Interestingly, we found that the proliferation of INS-1 cells was significantly increased at 48 h by combined treatment of palmitate and glucose. Moreover, benefit from the time-course quantitative data, we identified and validated two new molecular targets: Setd8 for cell replication and Rhob for apoptosis, demonstrating that our temporal dataset serves as a valuable resource to identify potential candidates for mechanistic studies of lipotoxicity and glucolipotoxicity in pancreatic β-cells.

Integrated Analysis of Summary Statistics to Identify Pleiotropic Genes and Pathways for the Comorbidity of Schizophrenia and Cardiometabolic Disease

“…As a member of methyltransferase family specifically targeting Histone H4 Lys20 for methylation, SETD8 plays an important role in cellular senescence, proliferation and apoptosis (59)(60)(61). Consistent with our results, multiple experiments indicated that changed expression level of SETD8 may affect insulinoma cell proliferation (62), hyperglycemic memory (63), and lipid metabolism (64). One study has shown that reducing the expression levels of SETD8 may contribute to altered hippocampal cellular composition, impaired neurodevelopment, and subsequent neurocognitive impairment (65), which are associated with the phenotype of SCZ.…”

LncRNA LEGLTBC Functions as a ceRNA to Antagonize the Effects of miR-34a on the Downregulation of SIRT1 in Glucolipotoxicity-Induced INS-1 Beta Cell Oxidative Stress and Apoptosis

“…Hyperglycemia could aggravate lipotoxicity-induced beta cell dysfunction (glucolipotoxicity) [5, 6]. Recently, transcriptomics and proteomics have been successfully adopted to discover major changes of protein-coding genes and proteins in pancreatic INS-1 cells exposed to glucolipotoxicity [18, 19]. Here, we revealed for the first time that the incubation of INS-1 cells with HG/PA caused considerable modifications in lncRNA expression.…”

“…INS-1 cells were grown to confluence, stimulated with 0.5 mM PA in the presence of 25 mM glucose (HG) for 24 h. The cell line and incubation conditions were chosen because 25 mM glucose/0.5 mM PA has been demonstrated to induce obvious glucolipotoxicity in INS-1 cells. Accordingly, this cell model has been used to explore the glucolipotoxicity-induced changes of mRNA microarray chips and proteomics [18, 19].…”

The Combination of Whole Cell Lipidomics Analysis and Single Cell Confocal Imaging of Fluidity and Micropolarity Provides Insight into Stress-Induced Lipid Turnover in Subcellular Organelles of Pancreatic Beta Cells

“…Other mass spectrometry methods have also been used to study beta cells. Recent temporal analysis of palmitic acid-treated INS-1 beta cells was based on isobaric labeling-based mass spectrometry and bioinformatics [64]. It highlighted altered cholesterol and fatty acid metabolism as early toxic events associated with ER stress.…”