Transcriptome analysis of islets from diabetes‐resistant and diabetes‐prone obese mice reveals novel gene regulatory networks involved in beta‐cell compensation and failure

Abstract

The mechanisms underpinning beta-cell compensation for obesity-associated insulin resistance and beta-cell failure in type 2 diabetes remain poorly understood. We used a large-scale strategy to determine the time-dependent transcriptomic changes in islets of diabetes-prone db/db and diabetes-resistant ob/ob mice at 6 and 16 weeks of age. Differentially expressed genes were subjected to cluster, gene ontology, pathway and gene set enrichment analyses. A distinctive gene expression pattern was observed in 16 week db/db islets in comparison to the other groups with alterations in transcriptional regulators of islet cell identity, upregulation of glucose/lipid metabolism, and various stress response genes, and downregulation of specific amino acid transport and metabolism genes. In contrast, ob/ob islets displayed a coordinated downregulation of metabolic and stress response genes at 6 weeks of age, suggestive of a preemptive reconfiguration in these islets to lower the threshold of metabolic activation in response to increased insulin demand thereby preserving beta-cell function and preventing cellular stress. In addition, amino acid transport and metabolism genes were upregulated in ob/ob islets, suggesting an important role of glutamate metabolism in beta-cell compensation. Gene set enrichment analysis of differentially expressed genes identified the enrichment of binding motifs for transcription factors, FOXO4, NFATC1, and MAZ. siRNA-mediated knockdown of these genes in MIN6 cells altered cell death, insulin secretion, and stress gene expression. In conclusion, these data revealed novel gene regulatory networks involved in beta-cell compensation and failure. Preemptive metabolic reconfiguration in diabetes-resistant islets may dampen metabolic activation and cellular stress during obesity.

Proteomic Analysis of Skeletal Muscle and White Adipose Tissue after Aerobic Exercise Training in High Fat Diet Induced Obese Mice

“…Previous proteomic studies investigating the effect of exercise on skeletal muscle have identified several differentially regulated proteins that ameliorate IR [ 23 ]. Our study further revealed a number of AE-regulated skeletal muscle proteins that can help improve IR, such as MKNK1 [ 24 ], FRDA [ 25 ], and ETFD [ 26 ]. In support of our findings, previous studies of transcriptome analyses of diabetes-prone and diabetes-resistant obese mice disclosed that the downregulation of MKNK1 in pancreatic islets is associated with diabetes [ 24 ].…”

“…Our study further revealed a number of AE-regulated skeletal muscle proteins that can help improve IR, such as MKNK1 [ 24 ], FRDA [ 25 ], and ETFD [ 26 ]. In support of our findings, previous studies of transcriptome analyses of diabetes-prone and diabetes-resistant obese mice disclosed that the downregulation of MKNK1 in pancreatic islets is associated with diabetes [ 24 ]. In addition, our results show that ETFD was upregulated in skeletal muscle but downregulated in EFP after AE, indicating that the regulation of this protein may differ between tissues.…”

Western blot normalization: Time to choose a proper loading control seriously

“…There were 2 transcripts relative to actin and 4 transcripts relative to tubulin changing significantly in the aortas of Angiotensin II‐infused mice (Table S5). For diabetes mellitus, streptozotocin injected mice (GSE179718 [39], GSE179717 [39], and GSE155377), diabetes‐prone db/db mice (GSE169275 [40] and GSE141411 [41]), and diabetes‐resistant ob/ob mice (GSE169275 [39]) were analyzed. As a result, 1 transcript about actin and 1 transcript about tubulin changed significantly in visceral adipose tissue of streptozotocin‐injected mice.…”

The Genetic Variability of Members of the SLC38 Family of Amino Acid Transporters (SLC38A3, SLC38A7 and SLC38A9) Affects Susceptibility to Type 2 Diabetes and Vascular Complications

“…Several evidence support a role for SLC38A3 in glucose homeostasis. SLC38A3 induction mediates glutamine transport in β-cells of pancreas [ 29 ], and its downregulation was found in islets of diabetes-prone db/db mice [ 30 ]. Studies reported that elevated plasma levels of glutamine induce the uptake of this AA by SLC38A3 with consequent stimulation of insulin secretion through the conversion of glutamine to glutamate [ 27 , 31 ].…”