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We have reported that partial PERK attenuation using PERK inhibitors (PI) enhanced glucose-stimulated insulin secretion (GSIS) from pancreatic islets and mice through induction of ER chaperone BIP. Therefore, we investigated if PI would have the same effects in a diabetic condition as well. GSK2606414 was treated to mouse islets under 20-mM glucose and 0.5-mM palmitate to examine GSIS. To generate a mouse model of type 2 diabetes mellitus (DM), male C57BL/6J mice were fed with high-fat diet and injected with streptozotocin. Several doses (6–16 mg/kg/day) of GSK2656157 and glimepiride were administrated to the mice for 8 weeks, and metabolic phenotypes were evaluated such as body weight, blood glucose levels, insulin secretion and sensitivity, and then changes in the pancreas were measured. High-glucose and palmitate treatment significantly increased PERK phosphorylation in the isolated islets. Suppression of GSIS and glucose-stimulated Ca2+ transit was also observed. PI at 40 nM which decreased PERK phosphorylation by 40% significantly recovered the GSIS and cytosolic calcium. In the mice where significant weight gain and prominent hyperglycemia were induced, PI at 10 mg/kg/day significantly enhanced GSIS and reduced blood glucose levels compared to the vehicle. The effects were similar to those by 10 mg/kg/day of glimepiride. Administration of PI did not induce changes in beta cell mass or pancreatic insulin contents, however, high dose PI decreased pancreatic weight. PI at low dose significantly enhanced GSIS in vitro and in vivo under metabolic stress and improved hyperglycemia in the mice mimicking type 2 DM, suggesting a potential as a new therapeutic approach for type 2 DM. • Low-dose PI increases GSIS in islets under stress by high-glucose and palmitate. • Low-dose PI improves GSIS and hyperglycemia in a type 2 DM mouse model. • Low-dose PI does not affect pancreas weight and beta cell mass in the mice. • Low-dose PI has a therapeutic potential for type 2 DM as an insulin secretagogue. [ABSTRACT FROM AUTHOR]

Highlights: [•] Repeated restraint stress gives rise to susceptible and resilient responses. [•] Different stress susceptibility is associated with different anxiety behavior. [•] Basal level of corticosterone is strongly correlated with stress susceptibility. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this study was to evaluate the effects of autologous islet transplantation (ITx) on glucose homeostasis and insulin secretory function after partial pancreatectomy (Px). Fourteen nondiabetic patients who underwent distal Px and autologous ITx for benign pancreatic tumors were enrolled in the study (Px + ITx group). Fourteen normal glucose-tolerant controls and 6 Px without ITx controls were recruited, and all groups were followed over a 24-month period. They performed the 75-g oral glucose tolerance test and the 1-mg glucagon stimulation test. Hemoglobin A1c was measured, and indices of insulin secretion were calculated. In the Px + ITx group, insulin secretion increased after a nadir at 6 months. Glucose tolerance, which had been abruptly impaired immediately after Px, recovered until 6 months and stabilized thereafter. As a result, differences in glucose intolerance emerged between the subjects in the Px group and those in the Px + ITx group at 24 months after Px. Characteristic variables in the better insulin secretory subjects in the Px + ITx group included younger age, less extensive pancreas resection, and a greater number of total islets. In summary, delayed amelioration of glucose intolerance was induced by autologous ITx after partial Px, even with a small number of islets. [Copyright &y& Elsevier]

Summary: Autophagy is a cellular degradation-recycling system for aggregated proteins and damaged organelles. Although dysregulated autophagy is implicated in various diseases including neurodegeneration, its role in pancreatic β cells and glucose homeostasis has not been described. We produced mice with β cell-specific deletion of Atg7 (autophagy-related 7). Atg7 mutant mice showed impaired glucose tolerance and decreased serum insulin level. β cell mass and pancreatic insulin content were reduced because of increased apoptosis and decreased proliferation of β cells. Physiological studies showed reduced basal and glucose-stimulated insulin secretion and impaired glucose-induced cytosolic Ca2+ transients in autophagy-deficient β cells. Morphologic analysis revealed accumulation of ubiquitinated protein aggregates colocalized with p62, which was accompanied by mitochondrial swelling, endoplasmic reticulum distension, and vacuolar changes in β cells. These results suggest that autophagy is necessary to maintain structure, mass and function of pancreatic β cells, and its impairment causes insulin deficiency and hyperglycemia because of abnormal turnover and function of cellular organelles. [Copyright &y& Elsevier]

Aims: There could be an overlap of monogenic diabetes and early onset type 2 diabetes in those who are diagnosed before age of 30years. Genetic diagnosis in these patients might improve the quality of care. A limited number of studies have used whole exome sequencing (WES) in Asian patients with early onset diabetes, and the clinical utility of WES is largely unknown.Methods: We performed whole exome capture and massive parallel sequencing in 28 patients with early onset diabetes. Those who had a strong family history of diabetes were preferentially enrolled. Rare and non-silent variants in 29 genes known to cause monogenic diabetes, including 12 maturity-onset diabetes of the young (MODY) genes, were investigated for pathogenicity.Results: The average depth of on-target WES reads was 97 X. A total of four pathogenic or likely pathogenic rare missense variants (p.Leu319Pro in HNF4A, p.His103Tyr and p.Arg74Gln in ABCC8, and p.Leu139Val in HNF1A) in MODY genes were identified in three patients. Although four rare non-silent variants in MODY genes (p.Arg183Cys in PAX4, p.Val139Ile and p.Pro740fs in CEL, and p.Val147Ile in HNF4A) and two rare non-silent variants in monogenic diabetes genes (p.Glu169Lys in WFS1, and p.Pro407Gln in GATA4) were identified, their pathogenicity was uncertain or likely benign.Conclusions: WES could be an initial option for genetic testing in patients with early onset diabetes. However, sufficient and universal coverage of genes of interest is required. In addition, it could be difficult to interpret variant pathogenicity, and these cases might require further validation. [ABSTRACT FROM AUTHOR]

Silencing target genes such as inducible nitric oxide synthase ( iNOS ) using small interfering double-stranded RNA (siRNA) in islet cells has been attempted to enhance the survival of transplanted islets. However, the efficient and safe delivery of siRNA into intact islets is challenging. Here, we prepared R3V6 peptides containing a three-arginine stretch and a six-valine stretch, which form micelles with hydrophobic valine cores and cationic arginine surfaces in aqueous solution, to co-deliver siRNA and cytoprotective hydrophobic drugs to islet cells. The cationic surfaces bound to the negatively charged iNOS siRNA, and the hydrophobic core was loaded with 17β-estradiol (E2), which exerts anti-apoptotic effects on the islet cells. The E2-loaded R3V6 peptide micelles delivered siRNA-5′-FITC to mouse islets more efficiently than did Lipofectamine 2000, and without cytotoxicity. The micelle complexes containing siRNA-iNOS knocked down the expression of iNOS mRNA by >60% in islets and reduced cytokine-induced apoptotic cell death in vitro significantly. The delivery of siRNA-iNOS and E2 simultaneously using E2-loaded R3V6 peptide micelles improved the diabetes reversal rate of marginal mass islet transplantation into the renal subcapsular space of diabetic syngeneic mice significantly compared with the siRNA-iNOS and E2 alone treatment control groups. Our results demonstrated that the co-delivery of siRNA and a cytoprotective drug within a single non-toxic carrier, R3V6 peptide micelles, provides a novel rational strategy for combined ex vivo islet therapy to improve the outcome of islet transplantation. [ABSTRACT FROM AUTHOR]

Various investigators have attempted to overcome the shortage of available hematopoietic stem/progenitor cells (HSPCs) by facilitating their engraftment after transplantation. Preconditioning of HSPCs with the granulocyte-derived cationic peptide LL-37 has been suggested as a useful strategy to facilitate engraftment of transplanted cells by enhancing their responsiveness to CXCL12. In this study, we evaluated whether LL-37 preconditioning is acceptable for clinical application. We found that the effect of LL-37 preconditioning was specific to clonogenic cells and was mediated specifically by increased calcium influx with the activation of downstream signaling through mammalian target of rapamycin complex 1 (mTORC1). Because hyperactivation of mTORC1 and the disruption of 5' adenosine monophosphate-activated protein kinase (AMPK) are known to deplete HSPC pools, we compared the repopulation capacity of HSPCs preconditioned with LL-37 and those preconditioned with AMPK activator (AICAR). In vivo competitive repopulation experiments revealed that LL-37 preconditioning impairs long-term repopulation of transplanted HSPCs, suggesting that this strategy might not acceptable for clinical applications in which long-term repopulation capacity is a prerequisite. AICAR preconditioning dramatically enhanced the long-term repopulation of transplanted HSPCs, however. Taken together, these results suggest that future strategies to ensure successful transplantation outcomes should focus on protecting HSPCs from various stimuli during their homing to the bone marrow niches rather than activating them before transplantation. [ABSTRACT FROM AUTHOR]