Project description:Dysfunction of pancreatic alpha cells contributes to the pathophysiology of diabetes. Features of diabetic alpha cell dysfunction include glucagon hypersecretion, defects in proglucagon processing, and altered transcriptomic profile. The lack of an in vitro human alpha cell model has prevented the investigation, and potential correction, of these dysfunctional phenotypes. Here, we show that induction of endoplasmic reticulum stress in stem cell-derived alpha (SC-α) cells induces hypersecretion of glucagon. ER stress also increases the secretion of glicentin and expression of GLP-1, peptides produced by alternate cleavage of proglucagon by the prohormone convertase 1 (PC1/3) enzyme. Additionally, ER stress establishes a diabetic transcriptional state in SC-α cells characterized by downregulation of MAFB, as well as glycolysis and oxidative phosphorylation pathways. We show that sunitinib, a tyrosine kinase inhibitor, protects SC-α cells against the ER stress-induced glucagon hypersecretion phenotype. Thus, SC-α cell model can advance our knowledge of islets in health and diabetes.
Project description:Dysfunction of pancreatic alpha cells contributes to the pathophysiology of diabetes. Features of diabetic alpha cell dysfunction include glucagon hypersecretion, defects in proglucagon processing, and altered transcriptomic profile. The lack of an in vitro human alpha cell model has prevented the investigation, and potential correction, of these dysfunctional phenotypes. Here, we show that induction of endoplasmic reticulum stress in stem cell-derived alpha (SC-α) cells induces hypersecretion of glucagon. ER stress also increases the secretion of glicentin and expression of GLP-1, peptides produced by alternate cleavage of proglucagon by the prohormone convertase 1 (PC1/3) enzyme. Additionally, ER stress establishes a diabetic transcriptional state in SC-α cells characterized by downregulation of MAFB, as well as glycolysis and oxidative phosphorylation pathways. We show that sunitinib, a tyrosine kinase inhibitor, protects SC-α cells against the ER stress-induced glucagon hypersecretion phenotype. Thus, SC-α cell model can advance our knowledge of islets in health and diabetes.
Project description:Diabetes is a known risk factor for various cardiovascular complications, mediated by endothelial dysfunction. Despite the high prevalence of this metabolic disorder, there is a lack of in vitro models that recapitulate the complexity of genetic and environmental factors associated with diabetic endothelial dysfunction. Here, we utilized human induced pluripotent stem cell (iPSC)-derived endothelial cells (ECs) to develop in vitro models of diabetic endothelial dysfunction. We found that the diabetic phenotype was recapitulated in diabetic patient-derived iPSC-ECs, even in the absence of a diabetogenic environment. Subsequent exposure with culture conditions that mimic the diabetic clinical chemistry induced a diabetic phenotype in healthy iPSC-ECs but did not affect the already dysfunctional diabetic iPSC-ECs. RNA-seq analysis revealed extensive transcriptome-wide differences between cells derived from healthy individuals and diabetic patients. The in vitro disease models were used as a screening platform which identified angiotensin receptor blockers (ARBs) that improved endothelial function in vitro for each patient. In summary, we present in vitro models of diabetic endothelial dysfunction using iPSC technology, taking into account the complexity of genetic and environmental factors in the metabolic disorder. Our study provides novel insights into the pathophysiology of diabetic endothelial dysfunction and highlights the potential of iPSC-based models for drug discovery and personalized medicine.
Project description:Background: In the diabetic heart the β-adrenergic response is altered partly by down-regulation of the β1-adrenoceptor, reducing its positive inotropic effect and up-regulation of the β3-adrenoceptor, increasing its negative inotropic effect. Statins have clinical benefits on morbidity and mortality in diabetic patients which are attributed to âpleiotropicâ effects. The objective of our study was to investigate the role of statin treatment on β-adrenergic dysfunction in diabetic rat cardiomyocytes. Methods: β-adrenergic responses were investigated in vivo (echocardiography) and ex vivo (left ventricular papillary muscles) in healthy and streptozotocin-induced diabetic rats, who were pre-treated or not by oral atorvastatin over 15 days (50 mg.kg-1.day-1). Micro-array analysis and immunoblotting were performed in left ventricular homogenates. Data are presented as mean percentage of baseline ± SD. Results: Atorvastatin restored the impaired positive inotropic effect of β-adrenergic stimulation in diabetic hearts compared with healthy hearts both in vivo and ex vivo but did not suppress the diastolic dysfunction of diabetes. Atorvastatin changed the RNA expression of 9 genes in the β-adrenergic pathway and corrected the protein expression of β1-adrenoceptor and β1/β3-adrenoceptor ratio, and multidrug resistance protein 4 (MRP4). Nitric oxide synthase (NOS) inhibition abolished the beneficial effects of atorvastatin on the β-adrenoceptor response. Conclusions: Atorvastatin restored the positive inotropic effect of the β-adrenoceptor stimulation in diabetic cardiomyopathy. This effect is mediated by multiple modifications in expression of proteins in the β-adrenergic signaling pathway, particularly through the NOS pathway.
Project description:The majority of diabetics are susceptible to cardiac dysfunction and heart failure, while conventional drug therapy cannot correct diabetic cardiomyopathy (DCM) progression. Herein, we assessed the potential role and therapeutic value of ubiquitin-specific protease 28 (USP28) on the metabolic vulnerability of DCM. cardiac USP28 deficient diabetic mice showed cardiac dysfunction, lipid accumulation, and mitochondrial disarrangement, compared to their controls. Conversely, USP28 overexpression improved systolic and diastolic dysfunction and ameliorated cardiac hypertrophy and fibrosis in the diabetic heart. Mechanistically, USP28 directly interacted with peroxisome proliferator-activated receptor α (PPARα), deubiquitinating and stabilizing PPARα (Lys152) to promote mitofusin 2 (Mfn2) transcription, thereby impeding mitochondrial morphofunctional defects.
Project description:Endothelial dysfunction underlies several vascular complications including diabetes and atherosclerosis. However, the underlying role of long non-coding RNAs (lncRNAs) remains poorly understood. This study elucidated the role of lncRNA Gm39822 in regulating endothelial dysfunction under healthy and diabetic conditions. Our data revealed that Gm39822 is enriched and upregulated in non-diabetic endothelial cells (ECs) when exposed to high glucose or inflammatory cytokines (TNF-a and IL-1b). Gm39822 overexpression promoted the expression of vascular cell adhesion molecule-1 (VCAM-1) and the adhesion of leukocytes in non-diabetic ECs but not in diabetic ECs. Conversely, Gm39822 silencing reduced VCAM1 expression and leukocyte adhesion in non-diabetic ECs and not in diabetic ECs. Gm39822 deficiency reduced the expression of inflammatory mediators (including p-P65, P65, P50, p-P38, P38. P-ERK1/2 and ERK1/2) in non-diabetic ECs. Furthermore, Gm39822 knockdown inhibited the secretion of pro-inflammatory cytokines including TNF-a, IL-1b, and IL-6, suggesting that Gm39822 regulates EC inflammatory responses. Mechanistically, we identified C1D, a nuclear enriched corepressor, as an interacting partner of Gm39822 that could play an important role in mediating Gm39822 functions in non-diabetic ECs. Collectively, our results identify a novel lncRNA Gm39822 and provide insights into the molecular mechanisms underlying endothelial dysfunction. These findings highlight Gm39822 as a potential therapeutic target for mitigating vascular complications associated with non-diabetic endothelial dysfunction.