Classically, exit from the endoplasmic reticulum (ER) is rate-limiting for secretory protein trafficking because protein folding/assembly occurs there. In this study, we have exploited "hPro-CpepSfGFP," a human proinsulin bearing "superfolder" green fluorescent C-peptide expressed in pancreatic β cells where it is processed to human insulin and CpepSfGFP. Remarkably, steady-state accumulation of hPro-CpepSfGFP and endogenous proinsulin is in the Golgi region, as if final stages of protein folding/assembly were occurring there. The Golgi regional distribution of proinsulin is dynamic, influenced by fasting/refeeding, and increased with β cell zinc deficiency. However, coexpression of ER-entrapped mutant proinsulin-C(A7)Y shifts the steady-state distribution of wild-type proinsulin to the ER. Endogenous proinsulin coprecipitates with hPro-CpepSfGFP and even more so with hProC(A7)Y-CpepSfGFP. Using Cerulean and Venus-tagged proinsulins, we find that both WT-WT and WT-mutant proinsulin pairs exhibit FRET. The data demonstrate that wild-type proinsulin dimerizes within the ER but accumulates at a poorly recognized slow step within the Golgi region, reflecting either slow kinetics of proinsulin hexamerization, steps in formation of nascent secretory granules, or other unknown molecular events. However, in the presence of ongoing misfolding of a subpopulation of proinsulin in β cells, the rate-limiting step in transport of the remaining proinsulin shifts to the ER.
Background/aims: Gestational Diabetes Mellitus (GDM), a prevalent complication in pregnancy, is characterized by the Diabetes Association as diabetes diagnosed in the second or third trimester, often remaining asymptomatic. This study investigates the intricate effects of Streptozotocin on pregnant rats, unraveling its impact on Gestational Type 2 Diabetes (GTD). The research delves into the potential therapeutic roles of mesenchymal stem cells (MSCs) and olive leaf extract (OLE) in mitigating the consequences of Streptozotocin-induced pancreatic impairment.
Introduction: Ethnic disparities in the prevalence and pathophysiology of type 2 diabetes are well documented, but prospective data on insulin dynamics vis-à-vis pre-diabetes/early dysglycemia risk in diverse populations are scant.
Research Design And Methods: We analyzed insulin secretion, sensitivity, and clearance among participants in the Pathobiology of Prediabetes in a Biracial Cohort (POP-ABC) study. The POP-ABC study followed initially normoglycemic offspring of parents with type 2 diabetes for 5.
Background: Obesity is a global issue, with over 1.9 billion adults overweight. Disruption of circadian rhythms (CR) leads to obesity and metabolic disorders.
Background: Older adults with type 1 diabetes are at risk for serious hypoglycemia. Automated insulin delivery can reduce risk but has not been sufficiently evaluated in this population.
Methods: We conducted a multicenter, randomized crossover trial in adults older than or equal to 65 years of age with type 1 diabetes.
Background: Cholesterol-lowering medications, blood pressure medication, insulin, and exogenous hormones (including hormone replacement therapy, oral contraceptives, and minipills) are commonly utilized in clinical practice. Recent studies indicate that the use of these medications may significantly influence the occurrence and progression of cerebral infarction. This study aims to investigate the relationship between these medications and cerebral infarction using Mendelian randomization (MR) analysis, with the goal of offering valuable insights for the clinical management of cerebral infarction.
