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1.
Ecotoxicol Environ Saf ; 201: 110802, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32531573

RESUMO

Extended exposure to inorganic arsenic through contaminated drinking water has been linked with increased incidence of diabetes mellitus. The most common exposure occurs through the consumption of contaminated drinking water mainly through geogenic sources of inorganic arsenic. Epigenetic modifications are important mechanisms through which environmental pollutants could exert their toxic effects. Bisulfite sequencing polymerase chain reaction method followed by Sanger sequencing was performed for DNA methylation analysis. Our results showed that sodium arsenite treatment significantly reduced insulin secretion in pancreatic islets. It was revealed that the methylation of glucose transporter 2 (Glut2) gene was changed at two cytosine-phosphate-guanine (CpG) sites (-1743, -1734) in the promoter region of the sodium arsenite-treated group comparing to the control. No changes were observed in the methylation status of peroxisome proliferator-activated receptor-gamma (PPARγ), pancreatic and duodenal homeobox 1 (Pdx1) and insulin 2 (Ins2) CpG sites in the targeted regions. Measuring the gene expression level showed increase in Glut2 expression, while the expression of insulin (INS) and Pdx1 were significantly affected by sodium arsenite treatment. This study revealed that exposure to sodium arsenite changed the DNA methylation pattern of Glut2, a key transporter of glucose entry into the pancreatic beta cells (ß-cells). Our data suggested possible epigenetic-mediated toxicity mechanism for arsenite-induced ß-cells dysfunction. Further studies are needed to dissect the precise epigenetic modulatory activity of sodium arsenite that affect the biogenesis of insulin.


Assuntos
Arsenitos/toxicidade , Metilação de DNA/efeitos dos fármacos , Transportador de Glucose Tipo 2/genética , Insulina/metabolismo , Ilhotas Pancreáticas/efeitos dos fármacos , Compostos de Sódio/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Epigênese Genética/efeitos dos fármacos , Proteínas de Homeodomínio/genética , Técnicas In Vitro , Insulina/genética , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , Masculino , Regiões Promotoras Genéticas , Ratos , Ratos Wistar , Transativadores/genética
2.
Nutr Metab Cardiovasc Dis ; 30(7): 1216-1226, 2020 06 25.
Artigo em Inglês | MEDLINE | ID: mdl-32482454

RESUMO

BACKGROUND AND AIMS: Successful islet transplantation as a promising treatment of diabetes type 1 is threatened with the loss of islets during the pre-transplant culture due to hypoxia and oxidative stress-induced apoptosis. Therefore, optimization of culture in order to preserve the islets is a critical point. In this study, we investigated the effect of resveratrol, as a cytoprotective agent, on the cultured human islets. METHODS AND RESULTS: Isolated islets were treated with different concentrations of resveratrol for 24 and 72 h. Islets' viability, apoptosis, apoptosis markers, and insulin and C-peptide secretion, along with the production of reactive oxygen species (ROS), hypoxia inducible factor 1 alpha (HIF-1α), and its target genes in the islets were investigated. Our findings showed that the islets were exposed to hypoxia and oxidative stress after isolation and during culture. This insult induced apoptosis and decreased viability during 72 h. The presence of resveratrol significantly attenuated HIF-1α and ROS production, reduced apoptosis, promoted the VEGF secretion, and increased the insulin and C-peptide secretion. In this regard, resveratrol improved the islet's survival and function in the culture period. CONCLUSIONS: Using resveratrol can attenuate the stressful condition for the islets in the pre-transplant culture and subsequently ameliorate their viability and functionality that lead to successful outcome after clinical transplantation.


Assuntos
Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Ilhotas Pancreáticas/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Resveratrol/farmacologia , Adulto , Idoso , Peptídeo C/metabolismo , Hipóxia Celular , Sobrevivência Celular/efeitos dos fármacos , Citoproteção , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/patologia , Pessoa de Meia-Idade , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais , Técnicas de Cultura de Tecidos , Fator A de Crescimento do Endotélio Vascular/metabolismo
3.
J Nutr ; 150(8): 2061-2069, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32470982

RESUMO

BACKGROUND: Infusion of a complete amino acid mixture into normal late-gestation fetal sheep potentiates glucose-stimulated insulin secretion (GSIS). Leucine acutely stimulates insulin secretion in late-gestation fetal sheep and isolated fetal sheep islets in vitro. OBJECTIVES: We hypothesized that a 9-d leucine infusion would potentiate GSIS in fetal sheep. METHODS: Columbia-Rambouillet fetal sheep at 126 days of gestation received a 9-d leucine infusion to achieve a 50%-100% increase in leucine concentrations or a control infusion. At the end of the infusion we measured GSIS, pancreatic morphology, and expression of pancreatic mRNAs. Pancreatic islet endothelial cells (ECs) were isolated from fetal sheep and incubated with supplemental leucine or vascular endothelial growth factor A (VEGFA) followed by collection of mRNA. Data measured at multiple time points were compared with a repeated-measures 2-factor ANOVA. Data measured at 1 time point were compared using Student's t test or the Mann-Whitney test. RESULTS: Glucose-stimulated insulin concentrations were 80% higher in leucine-infused (LEU) fetuses than in controls (P < 0.05). In the pancreas, LEU fetuses had a higher proportion of islets >5000 µm2 than controls (75% more islets >5000 µm2; P < 0.05) and a larger proportion of the pancreas that stained for ß cells (12% greater; P < 0.05). Pancreatic and pancreatic islet vascularity were both 25% greater in LEU fetuses (P < 0.05). Pancreatic VEGFA and hepatocyte growth factor (HGF) mRNA expressions were 38% and 200% greater in LEU fetuses than in controls (P < 0.05), respectively. In isolated islet ECs, HGF mRNA was 20% and 50% higher after incubation in supplemental leucine (P < 0.05) or VEGFA (P < 0.01), respectively. CONCLUSIONS: A 9-d leucine infusion potentiates fetal GSIS, demonstrating that glucose and leucine act synergistically to stimulate insulin secretion in fetal sheep. A greater proportion of the pancreas being comprised of ß cells and higher pancreatic vascularity contributed to the higher GSIS.


Assuntos
Feto/efeitos dos fármacos , Insulina/metabolismo , Ilhotas Pancreáticas/efeitos dos fármacos , Animais , Esquema de Medicação , Feminino , Feto/fisiologia , Glucose/metabolismo , Técnica Clamp de Glucose , Ilhotas Pancreáticas/citologia , Ilhotas Pancreáticas/embriologia , Leucina/administração & dosagem , Leucina/farmacologia , Gravidez , Ovinos
4.
Adv Exp Med Biol ; 1221: 607-630, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32274728

RESUMO

Type 1 diabetes (T1D) results from autoimmune destruction of insulin-producing beta cells in pancreatic islets. The degradation of the glycosaminoglycan heparan sulfate (HS) by the endo-ß-D-glycosidase heparanase plays a critical role in multiple stages of the disease process. Heparanase aids (i) migration of inflammatory leukocytes from the vasculature to the islets, (ii) intra-islet invasion by insulitis leukocytes, and (iii) selective destruction of beta cells. These disease stages are marked by the solubilization of HS in the subendothelial basement membrane (BM), HS breakdown in the peri-islet BM, and the degradation of HS inside beta cells, respectively. Significantly, healthy islet beta cells are enriched in highly sulfated HS which is essential for their viability, protection from damage by reactive oxygen species (ROS), beta cell function and differentiation. Consequently, mouse and human beta cells but not glucagon-producing alpha cells (which contain less-sulfated HS) are exquisitely vulnerable to heparanase-mediated damage. In vitro, the death of HS-depleted mouse and human beta cells can be prevented by HS replacement using highly sulfated HS mimetics or analogues. T1D progression in NOD mice and recent-onset T1D in humans correlate with increased expression of heparanase by circulating leukocytes of myeloid origin and heparanase-expressing insulitis leukocytes. Treatment of NOD mice with the heparanase inhibitor and HS replacer, PI-88, significantly reduced T1D incidence by 50%, impaired the development of insulitis and preserved beta cell HS. These outcomes identified heparanase as a novel destructive tool in T1D, distinct from the conventional cytotoxic and apoptosis-inducing mechanisms of autoreactive T cells. In contrast to exogenous catalytically active heparanase, endogenous heparanase may function in HS homeostasis, gene expression and insulin secretion in normal beta cells and immune gene expression in leukocytes. In established diabetes, the interplay between hyperglycemia, local inflammatory cells (e.g. macrophages) and heparanase contributes to secondary micro- and macro-vascular disease. We have identified dual activity heparanase inhibitors/HS replacers as a novel class of therapeutic for preventing T1D progression and potentially for mitigating secondary vascular disease that develops with long-term T1D.


Assuntos
Diabetes Mellitus Tipo 1/enzimologia , Glucuronidase/metabolismo , Animais , Diabetes Mellitus Tipo 1/tratamento farmacológico , Diabetes Mellitus Tipo 1/patologia , Glucuronidase/antagonistas & inibidores , Humanos , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/enzimologia , Ilhotas Pancreáticas/patologia
5.
Br J Nutr ; 124(3): 247-255, 2020 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-32122411

RESUMO

Preliminary evidence has suggested that high-fat diets (HFD) enriched with SFA, but not MUFA, promote hyperinsulinaemia and pancreatic hypertrophy with insulin resistance. The objective of this study was to determine whether the substitution of dietary MUFA within a HFD could attenuate the progression of pancreatic islet dysfunction seen with prolonged SFA-HFD. For 32 weeks, C57BL/6J mice were fed either: (1) low-fat diet, (2) SFA-HFD or (3) SFA-HFD for 16 weeks, then switched to MUFA-HFD for 16 weeks (SFA-to-MUFA-HFD). Fasting insulin was assessed throughout the study; islets were isolated following the intervention. Substituting SFA with MUFA-HFD prevented the progression of hyperinsulinaemia observed in SFA-HFD mice (P < 0·001). Glucose-stimulated insulin secretion from isolated islets was reduced by SFA-HFD, yet not fully affected by SFA-to-MUFA-HFD. Markers of ß-cell identity (Ins2, Nkx6.1, Ngn3, Rfx6, Pdx1 and Pax6) were reduced, and islet inflammation was increased (IL-1ß, 3·0-fold, P = 0·007; CD68, 2·9-fold, P = 0·001; Il-6, 1·1-fold, P = 0·437) in SFA-HFD - effects not seen with SFA-to-MUFA-HFD. Switching to MUFA-HFD can partly attenuate the progression of SFA-HFD-induced hyperinsulinaemia, pancreatic inflammation and impairments in ß-cell function. While further work is required from a mechanistic perspective, dietary fat may mediate its effect in an IL-1ß-AMP-activated protein kinase α1-dependent fashion. Future work should assess the potential translation of the modulation of metabolic inflammation in man.


Assuntos
Dieta Hiperlipídica/métodos , Gorduras na Dieta/farmacologia , Ácidos Graxos Monoinsaturados/farmacologia , Ácidos Graxos/farmacologia , Hiperinsulinismo/dietoterapia , Animais , Modelos Animais de Doenças , Resistência à Insulina/fisiologia , Ilhotas Pancreáticas/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pâncreas/efeitos dos fármacos
6.
Development ; 147(7)2020 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-32165492

RESUMO

Although the developing pancreas is exquisitely sensitive to nutrient supply in utero, it is not entirely clear how nutrient-driven post-translational modification of proteins impacts the pancreas during development. We hypothesized that the nutrient-sensing enzyme O-GlcNAc transferase (Ogt), which catalyzes an O-GlcNAc-modification onto key target proteins, integrates nutrient-signaling networks to regulate cell survival and development. In this study, we investigated the heretofore unknown role of Ogt in exocrine and endocrine islet development. By genetic manipulation in vivo and by using morphometric and molecular analyses, such as immunofluorescence imaging and single cell RNA sequencing, we show the first evidence that Ogt regulates pancreas development. Genetic deletion of Ogt in the pancreatic epithelium (OgtKOPanc) causes pancreatic hypoplasia, in part by increased apoptosis and reduced levels of of Pdx1 protein. Transcriptomic analysis of single cell and bulk RNA sequencing uncovered cell-type heterogeneity and predicted upstream regulator proteins that mediate cell survival, including Pdx1, Ptf1a and p53, which are putative Ogt targets. In conclusion, these findings underscore the requirement of O-GlcNAcylation during pancreas development and show that Ogt is essential for pancreatic progenitor survival, providing a novel mechanistic link between nutrients and pancreas development.


Assuntos
Acetilglucosamina/metabolismo , Ilhotas Pancreáticas/efeitos dos fármacos , Nutrientes/farmacologia , Pâncreas Exócrino/efeitos dos fármacos , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Animais , Embrião de Mamíferos , Feminino , Ilhotas Pancreáticas/embriologia , Ilhotas Pancreáticas/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , N-Acetilglucosaminiltransferases/efeitos dos fármacos , N-Acetilglucosaminiltransferases/metabolismo , Pâncreas Exócrino/embriologia , Pâncreas Exócrino/metabolismo , Transdução de Sinais/efeitos dos fármacos
7.
Acta Diabetol ; 57(8): 1009-1018, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32221724

RESUMO

AIMS: The minimal-invasive transplantation of pancreatic islets is a promising approach to treat diabetes mellitus type 1. However, islet transplantation is still hampered by the insufficient process of graft revascularization, leading to a poor clinical outcome. Accordingly, the identification of novel compounds, which accelerate and improve the revascularization of transplanted islets, is of great clinical interest. Previous studies have shown that darbepoetin (DPO)-α, a long lasting analogue of erythropoietin, is capable of promoting angiogenesis. Hence, we investigated in this study whether DPO improves the revascularization of transplanted islets. METHODS: Islets were isolated from green fluorescent protein-positive FVB/N donor mice and transplanted into dorsal skinfold chambers of FVB/N wild-type animals, which were treated with DPO low dose (2.5 µg/kg), DPO high dose (10 µg/kg) or vehicle (control). The revascularization was assessed by repetitive intravital fluorescence microscopy over an observation period of 14 days. Subsequently, the cellular composition of the grafts was analyzed by immunohistochemistry. RESULTS: The present study shows that neither low- nor high-dose DPO treatment accelerates the revascularization of free pancreatic islet grafts. However, high-dose DPO treatment increased the blood volume flow of the transplanted islet. CONCLUSIONS: These findings demonstrated that DPO treatment does not affect the revascularization of transplanted islets. However, the glycoprotein increases the blood volume flow of the grafts, which results in an improved microvascular function and may facilitate successful transplantation.


Assuntos
Darbepoetina alfa/farmacologia , Transplante das Ilhotas Pancreáticas , Ilhotas Pancreáticas/irrigação sanguínea , Fluxo Sanguíneo Regional/efeitos dos fármacos , Transplantes/irrigação sanguínea , Animais , Ilhotas Pancreáticas/efeitos dos fármacos , Camundongos , Camundongos Transgênicos , Neovascularização Fisiológica/efeitos dos fármacos , Transplantes/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos
8.
Cell Mol Life Sci ; 77(22): 4709-4723, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31925452

RESUMO

AIMS: Endocannabinoids are lipid mediators involved in the regulation of glucose homeostasis. They interact with the canonical cannabinoid receptors CB1 and CB2, and it is now apparent that some cannabinoid receptor ligands are also agonists at GPR55. Thus, CB1 antagonists such as SR141716A, also known as rimonabant, and AM251 act as GPR55 agonists in some cell types. The complex pharmacological properties of cannabinoids make it difficult to fully identify the relative importance of CB1 and GPR55 in the functional effects of SR141716A, and AM251. Here, we determine whether SR141716A and AM251 regulation of mouse and human islet function is through their action as GPR55 agonists. METHODS: Islets isolated from Gpr55+/+ and Gpr55-/- mice and human donors were incubated in the absence or presence of 10 µM SR141716A or AM251, concentrations that are known to activate GPR55. Insulin secretion, cAMP, IP1, apoptosis and ß-cell proliferation were quantified by standard techniques. RESULTS: Our results provide the first evidence that SR141716A and AM251 are not GPR55 agonists in islets, as their effects are maintained in islets isolated from Gpr55-/- mice. Their signalling through Gq-coupled cascades to induce insulin secretion and human ß-cell proliferation, and protect against apoptosis in vitro, indicate that they have direct beneficial effects on islet function. CONCLUSION: These observations may be useful in directing development of peripherally restricted novel therapeutics that are structurally related to SR141716A and AM251, and which potentiate glucose-induced insulin secretion and stimulate ß-cell proliferation.


Assuntos
Canabinoides/metabolismo , Ilhotas Pancreáticas/efeitos dos fármacos , Piperidinas/farmacologia , Pirazóis/farmacologia , Receptores de Canabinoides/metabolismo , Rimonabanto/farmacologia , Transdução de Sinais/efeitos dos fármacos , Animais , Proliferação de Células/efeitos dos fármacos , Endocanabinoides/metabolismo , Feminino , Humanos , Insulina , Secreção de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , Ligantes , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Pessoa de Meia-Idade , Receptores Acoplados a Proteínas-G/metabolismo
9.
ACS Appl Mater Interfaces ; 12(5): 5462-5475, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31927945

RESUMO

Islet transplantation has been considered the most promising therapeutic option with the potential to restore the physiological regulation of blood glucose concentrations in type 1 diabetes treatment. However, islets suffer from oxidative stress and nonspecific inflammation in the early stage of transplantation, which attributed to the leading cause of islet graft failure. Our previous study reported that bilirubin exerted antioxidative and anti-inflammatory effects on hypothermic preserved islets, which inspire us to utilize bilirubin to address the survival issue of grafted islets. However, the application of bilirubin for islet transplantation is limited by its poor solubility and fast clearance. In this study, we designed a supramolecular carrier (PLCD) that could improve the solubility of bilirubin and slowly release bilirubin to protect islets after cotransplantation. PLCD was synthesized by conjugating activated ß-cyclodextrin (ß-CD) to the side chain of ε-polylysine (PLL) and acted as a carrier to load bilirubin via host-guest interactions. The constructed bilirubin supramolecular system (PLCD-BR) significantly improved the solubility and prolonged the action time of bilirubin. In vitro results confirmed that PLCD-BR coculture substantially enhanced the resistance of islets to excessive oxidative stress and proinflammatory stimulation and maximumly maintained the islet function. In vivo, PLCD could prolong drug duration at the transplant site, and the localized released bilirubin could protect the islets from oxidative stress and suppress the production of inflammatory cytokines. Crucially, islet transplantation with PLCD-BR significantly extended the stable blood glucose time of diabetic mice and produced a faster glucose clearance compared to those cotransplanted with free bilirubin. Additionally, immunohistochemical analysis showed that PLCD-BR had superior antioxidative and anti-inflammatory abilities and beneficial effects on angiogenesis. These findings demonstrate that the PLCD-BR has great potentials to support successful islet transplantation.


Assuntos
Anti-Inflamatórios/química , Bilirrubina/metabolismo , Estresse Oxidativo , Polilisina/química , beta-Ciclodextrinas/química , Animais , Anti-Inflamatórios/farmacologia , Bilirrubina/farmacologia , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Preparações de Ação Retardada , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/terapia , Concentração de Íons de Hidrogênio , Inflamação/metabolismo , Inflamação/prevenção & controle , Ilhotas Pancreáticas/citologia , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/patologia , Transplante das Ilhotas Pancreáticas , Lipopolissacarídeos/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Estresse Oxidativo/efeitos dos fármacos , Células RAW 264.7 , Fator de Necrose Tumoral alfa/metabolismo
10.
Sci Rep ; 10(1): 414, 2020 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-31942009

RESUMO

Cell replacement therapies hold great therapeutic potential. Nevertheless, our knowledge of the mechanisms governing the developmental processes is limited, impeding the quality of differentiation protocols. Generating insulin-expressing cells in vitro is no exception, with the guided series of differentiation events producing heterogeneous cell populations that display mixed pancreatic islet phenotypes and immaturity. The achievement of terminal differentiation ultimately requires the in vivo transplantation of, usually, encapsulated cells. Here we show the impact of cell confinement on the pancreatic islet signature during the guided differentiation of alginate encapsulated human induced pluripotent stem cells (hiPSCs). Our results show that encapsulation improves differentiation by significantly reshaping the proteome landscape of the cells towards an islet-like signature. Pathway analysis is suggestive of integrins transducing the encapsulation effect into intracellular signalling cascades promoting differentiation. These analyses provide a molecular framework for understanding the confinement effects on hiPSCs differentiation while confirming its importance for this process.


Assuntos
Alginatos/farmacologia , Biomarcadores/metabolismo , Diferenciação Celular , Células-Tronco Pluripotentes Induzidas/metabolismo , Integrinas/metabolismo , Ilhotas Pancreáticas/metabolismo , Proliferação de Células , Sobrevivência Celular , Células Cultivadas , Perfilação da Expressão Gênica , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Células-Tronco Pluripotentes Induzidas/efeitos dos fármacos , Insulina/metabolismo , Ilhotas Pancreáticas/citologia , Ilhotas Pancreáticas/efeitos dos fármacos , Fenótipo , Transdução de Sinais
11.
Proc Natl Acad Sci U S A ; 117(5): 2484-2495, 2020 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-31964806

RESUMO

Circadian clocks operative in pancreatic islets participate in the regulation of insulin secretion in humans and, if compromised, in the development of type 2 diabetes (T2D) in rodents. Here we demonstrate that human islet α- and ß-cells that bear attenuated clocks exhibit strongly disrupted insulin and glucagon granule docking and exocytosis. To examine whether compromised clocks play a role in the pathogenesis of T2D in humans, we quantified parameters of molecular clocks operative in human T2D islets at population, single islet, and single islet cell levels. Strikingly, our experiments reveal that islets from T2D patients contain clocks with diminished circadian amplitudes and reduced in vitro synchronization capacity compared to their nondiabetic counterparts. Moreover, our data suggest that islet clocks orchestrate temporal profiles of insulin and glucagon secretion in a physiological context. This regulation was disrupted in T2D subjects, implying a role for the islet cell-autonomous clocks in T2D progression. Finally, Nobiletin, an agonist of the core-clock proteins RORα/γ, boosted both circadian amplitude of T2D islet clocks and insulin secretion by these islets. Our study emphasizes a link between the circadian clockwork and T2D and proposes that clock modulators hold promise as putative therapeutic agents for this frequent disorder.


Assuntos
Ritmo Circadiano/efeitos dos fármacos , Diabetes Mellitus Tipo 2/metabolismo , Glucagon/metabolismo , Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , Adulto , Animais , Diabetes Mellitus Tipo 2/fisiopatologia , Exocitose/efeitos dos fármacos , Feminino , Flavonas/farmacologia , Humanos , Técnicas In Vitro , Ilhotas Pancreáticas/efeitos dos fármacos , Masculino , Camundongos , Pessoa de Meia-Idade , Adulto Jovem
12.
Food Chem Toxicol ; 135: 110894, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31644924

RESUMO

Acrylamide (AA), a food contaminant, caused islet remodeling and increased hepatic glycogen content in male rats, but the effect of AA on glucose homeostasis in female rats remains unclear. In this study, female SD rats were orally treated with 0, 15, or 30 mg/kg·bw AA for 3 weeks. The levels of fasting blood glucose (FBG), blood glucose after oral administration of glucose, plasma insulin and hepatic glycogen were measured. The histology of the pancreas was observed, and the transcription of key genes involved in glucose metabolism and insulin signaling in liver were determined. Compared with the control, exposure to 30 mg/kg·bw of AA significantly increased FBG level, reduced hepatic glycogen content and impaired glucose tolerance. Moreover, damaged islets were observed at 15 and 30 mg/kg·bw AA-exposed groups. In addition, AA exposure significantly promoted gluconeogenesis and glycogenolysis (up-regulation of pc, g6p and gp) and decreased glycolysis (down-regulation of gck and pfk). Alternations in these processes may be associated with decreased plasma insulin levels and inhibited insulin-regulated IRS/PI3K/Akt/Foxo1 signaling transduction under AA exposure. Overall, our findings demonstrated that AA disrupted glucose homeostasis and elevated FBG level in female rats possibly by interfering with glucose metabolism and hampering the physiological effect of insulin.


Assuntos
Acrilamida/efeitos adversos , Glicemia/metabolismo , Homeostase/efeitos dos fármacos , Animais , Feminino , Expressão Gênica/efeitos dos fármacos , Gluconeogênese/genética , Intolerância à Glucose/induzido quimicamente , Glicogenólise/genética , Glicólise/genética , Insulina/metabolismo , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/patologia , Fígado/efeitos dos fármacos , Glicogênio Hepático/metabolismo , Ratos Sprague-Dawley , Transdução de Sinais/genética
13.
Ann N Y Acad Sci ; 1461(1): 53-72, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-30937918

RESUMO

Obesity is the major contributing factor for the increased prevalence of type 2 diabetes (T2D) in recent years. Sustained positive influx of lipids is considered to be a precipitating factor for beta cell dysfunction and serves as a connection between obesity and T2D. Importantly, fatty acids (FA), a key building block of lipids, are a double-edged sword for beta cells. FA acutely increase glucose-stimulated insulin secretion through cell-surface receptor and intracellular pathways. However, chronic exposure to FA, combined with elevated glucose, impair the viability and function of beta cells in vitro and in animal models of obesity (glucolipotoxicity), providing an experimental basis for the propensity of beta cell demise under obesity in humans. To better understand the two-sided relationship between lipids and beta cells, we present a current view of acute and chronic handling of lipids by beta cells and implications for beta cell function and health. We also discuss an emerging role for lipid droplets (LD) in the dynamic regulation of lipid metabolism in beta cells and insulin secretion, along with a potential role for LD under nutritional stress in beta cells, and incorporate recent advancement in the field of lipid droplet biology.


Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Secreção de Insulina , Ilhotas Pancreáticas/metabolismo , Metabolismo dos Lipídeos , Animais , Glucose/metabolismo , Humanos , Secreção de Insulina/efeitos dos fármacos , Ilhotas Pancreáticas/efeitos dos fármacos , Metabolismo dos Lipídeos/efeitos dos fármacos , Lipídeos/toxicidade
14.
Phytother Res ; 34(1): 161-172, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31515869

RESUMO

Inflammatory cytokines such as interleukin-1ß, TNF-α, and interferon-γ are known to be involved in mediating ß-cells death in diabetes mellitus (DM). Thus, protecting from ß-cells death in patients with DM may be a useful target in alleviating symptoms of hyperglycemia. Traditional plant-based remedies have been used to treat DM for many centuries and may play a role in protecting ß-cell from death. An example of these remedies is Gymnema sylvestre (GS) extract. In this study, we investigated the effect of this plant extract on ß-cells apoptosis. Om Santal Adivasi (OSA®) maintained cell membrane integrity in MIN6 cells and mouse islets. Om Santal Adivasi significantly protected MIN6 cells and mouse islets from cytokine-induced apoptosis. In the presence of cytokines, OSA® significantly reduced the expression and activity of caspase-3. The antiapoptotic effect of OSA® as shown by microarray analysis is largely mediated by activating pathways involved in cell survival (mainly casein kinase II pathway) and the free radical scavenger system (specifically superoxide dismutase and catalase). This study indicates that the GS isolate OSA® protects against cytokine-induced apoptosis of ß-cells by increasing the expression of cell survival pathways and free radical scavenger system.


Assuntos
Citocinas/metabolismo , Gymnema sylvestre/química , Células Secretoras de Insulina/efeitos dos fármacos , Ilhotas Pancreáticas/efeitos dos fármacos , Extratos Vegetais/uso terapêutico , Animais , Apoptose , Perfilação da Expressão Gênica , Humanos , Masculino , Camundongos , Extratos Vegetais/farmacologia
15.
Toxicol Lett ; 320: 19-27, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31778773

RESUMO

The deleterious effects of glucocorticoids on glucose homeostasis limit their clinical use. There is substantial evidence demonstrating that islet function impaired by long-term glucocorticoids exposure is a core defect in the progression of impaired glucose tolerance to diabetes. The activity of heat-shock protein (Hsp) 90 is required to maintain the hormone-binding activity and stability of glucocorticoid receptor (GR). In the present study, Hsp90 inhibition by 17-DMAG counteracted dexamethasone-mediated inhibition of glucose-stimulated insulin secretion in isolated rat islets as well as expressions of neuropeptide Y (NPY) and somatostatin receptor 3 (SSTR3), two negative regulators of insulin secretion. Like 17-DMAG, both the pan-histone deacetylase (HDAC) inhibitor TSA and HDAC6 inhibitor Tubacin exhibited a similar action in protecting islet function against dexamethasone-induced injury, along with the downregulation of NPY and SSTR3 expressions. The hyperacetylation of Hsp90 by TSA and Tubacin disrupted its binding ability to GR and blocked dexamethasone-elicited nuclear translocation of GR in INS-1 ß-cell lines. In addition, Tubacin treatment triggered the GR protein degradation through the ubiquitin-proteasome pathway. These findings suggest that Hsp90 acetylation by inhibiting HDAC6 activity may be a potential strategy to prevent the development of steroid diabetes mellitus via alleviating glucocorticoid-impaired islet function.


Assuntos
Anilidas/farmacologia , Benzoquinonas/farmacologia , Dexametasona/toxicidade , Glucocorticoides/toxicidade , Proteínas de Choque Térmico HSP90/antagonistas & inibidores , Desacetilase 6 de Histona/antagonistas & inibidores , Inibidores de Histona Desacetilases/farmacologia , Ácidos Hidroxâmicos/farmacologia , Insulina/metabolismo , Ilhotas Pancreáticas/efeitos dos fármacos , Lactamas Macrocíclicas/farmacologia , Acetilação , Animais , Linhagem Celular , Proteínas de Choque Térmico HSP90/metabolismo , Desacetilase 6 de Histona/metabolismo , Ilhotas Pancreáticas/metabolismo , Masculino , Complexo de Endopeptidases do Proteassoma/metabolismo , Processamento de Proteína Pós-Traducional , Proteólise , Ratos Sprague-Dawley , Via Secretória , Técnicas de Cultura de Tecidos
16.
J Ethnopharmacol ; 248: 112356, 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-31669668

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Tinospora sinensis Lour. (Merr.) belongs to the family Menispermaceae and its stem extract have been used traditionally in broad aspects of therapeutic remedies including debility, dyspepsia, fever, jaundice, ulcer, bronchitis, urinary disease, skin disease, liver disease and diabetes. AIM OF THE STUDY: The aim of the study was to evaluate the protective effects of methanol extract of stem of Tinospora sinensis (METS) on streptozotocin induced pancreatic islet cell injuries of diabetic rats and its correlation to its phytochemical profiles. MATERIALS AND METHODS: A high-performance liquid chromatography technique (HPLC) was used to identify and quantify the major phytochemicals present in the METS. Diabetic rats were administered with METS at a dose of (100, 200 and 400 mg/kg respectively orally) and standard drug Metformin (300 mg/kg) was given orally to group serving positive control. Effect of the METS on glucose homeostasis, oxidative stress, antioxidant status, histopathology of pancreas and also on intracellular reactive oxygen species (ROS), mitochondrial membrane potential, apoptosis, cell cycle of pancreatic islet cells were studied in diabetic rats. RESULTS: The major phytochemicals identified and quantified by HPLC in the extract were berberine, caffeic acid, myricetin and ferulic acid. This result showed that methanol extract exhibited good antioxidant effect. The methanol extract of the plant prevented the diabetogenic effect of STZ and significantly lowered the fasting blood glucose level, glycated haemoglobin and increased insulin and C-peptide level in treated rats. METS reduced apoptosis of STZ treated islet cells by significantly decreasing pro-inflammatory cytokines (TNFα, IL6), intracellular ROS generation, lipid peroxidation, nitric oxide (NO) production and increasing mitochondrial membrane potential and sub-G0 peak area, enzymatic and nonenzymatic antioxidants. CONCLUSION: The results revealed that the methanol extract of the stem of the plant possesses protective effects against diabetes and associated complications.


Assuntos
Anti-Inflamatórios/farmacologia , Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Diabetes Mellitus Experimental/prevenção & controle , Hipoglicemiantes/farmacologia , Ilhotas Pancreáticas/efeitos dos fármacos , Extratos Vegetais/farmacologia , Tinospora , Animais , Anti-Inflamatórios/isolamento & purificação , Antioxidantes/isolamento & purificação , Glicemia/efeitos dos fármacos , Glicemia/metabolismo , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patologia , Hemoglobina A Glicada/metabolismo , Hipoglicemiantes/isolamento & purificação , Mediadores da Inflamação/metabolismo , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/patologia , Peroxidação de Lipídeos/efeitos dos fármacos , Lipídeos/sangue , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Estresse Oxidativo/efeitos dos fármacos , Extratos Vegetais/isolamento & purificação , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais , Estreptozocina , Tinospora/química
17.
Eur J Pharmacol ; 866: 172835, 2020 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-31794708

RESUMO

Diabetes mellitus is characterized by metabolic dysregulation associated with a number of health complications. More than 50% of patients with diabetes mellitus suffer from diabetic polyneuropathy, which involves the presence of peripheral nerve dysfunction symptoms. The aim of this study was to evaluate the potential of a new synthetic arginine-rich exendin-4 (Peptide D) in the treatment of complications caused by diabetes, including peripheral neuropathy, in rats. Diabetes was induced by administering streptozotocin (STZ). Three groups of diabetic rats were treated with Peptide D (0.1, 1, and 10 µg/kg). One group of diabetic rats was treated with Byetta® (1 µg/kg) for 80 days. Neuropathic pain development was assessed by tactile allodynia. STZ-treated rats showed an increased level of tactile allodynia unlike naïve animals. A histological study revealed that the diameter of the sciatic nerve fibers in STZ-treated rats was smaller than that of the naïve animals. An IHC study demonstrated decreased expression of myelin basic protein (MBP) in the sciatic nerve of diabetic rats compared to that in the naïve animals. Peptide D reduced the severity of tactile allodynia. This effect was more pronounced in the Peptide D treated groups than in the group treated with Byetta®. Peptide D and Byetta® treatment resulted in increased MBP expression in the sciatic nerve and increased diameter of myelinated nerve fibers. These findings suggest that poly-arginine peptides are promising agents for the treatment of peripheral polyneuropathies.


Assuntos
Arginina/química , Neuropatias Diabéticas/tratamento farmacológico , Exenatida/química , Exenatida/farmacologia , Animais , Glicemia/metabolismo , Neuropatias Diabéticas/sangue , Neuropatias Diabéticas/patologia , Neuropatias Diabéticas/fisiopatologia , Relação Dose-Resposta a Droga , Exenatida/uso terapêutico , Regulação da Expressão Gênica/efeitos dos fármacos , Hemoglobina A Glicada/metabolismo , Hiperalgesia/complicações , Insulina/metabolismo , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/patologia , Locomoção/efeitos dos fármacos , Masculino , Tamanho do Órgão/efeitos dos fármacos , Ratos , Ratos Wistar , Nervo Isquiático/efeitos dos fármacos , Nervo Isquiático/patologia
18.
Diabetes ; 69(3): 369-380, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31882563

RESUMO

The molecular mechanisms of ß-cell compensation to metabolic stress are poorly understood. We previously observed that nutrient-induced ß-cell proliferation in rats is dependent on epidermal growth factor receptor (EGFR) signaling. The aim of this study was to determine the role of the EGFR ligand heparin-binding EGF-like growth factor (HB-EGF) in the ß-cell proliferative response to glucose, a ß-cell mitogen and key regulator of ß-cell mass in response to increased insulin demand. We show that exposure of isolated rat and human islets to HB-EGF stimulates ß-cell proliferation. In rat islets, inhibition of EGFR or HB-EGF blocks the proliferative response not only to HB-EGF but also to glucose. Furthermore, knockdown of HB-EGF in rat islets blocks ß-cell proliferation in response to glucose ex vivo and in vivo in transplanted glucose-infused rats. Mechanistically, we demonstrate that HB-EGF mRNA levels are increased in ß-cells in response to glucose in a carbohydrate-response element-binding protein (ChREBP)-dependent manner. In addition, chromatin immunoprecipitation studies identified ChREBP binding sites in proximity to the HB-EGF gene. Finally, inhibition of Src family kinases, known to be involved in HB-EGF processing, abrogated glucose-induced ß-cell proliferation. Our findings identify a novel glucose/HB-EGF/EGFR axis implicated in ß-cell compensation to increased metabolic demand.


Assuntos
Proliferação de Células/genética , Receptores ErbB/metabolismo , Glucose/metabolismo , Fator de Crescimento Semelhante a EGF de Ligação à Heparina/genética , Células Secretoras de Insulina/metabolismo , Animais , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Proliferação de Células/efeitos dos fármacos , Imunoprecipitação da Cromatina , Receptores ErbB/antagonistas & inibidores , Técnicas de Silenciamento de Genes , Glucose/farmacologia , Fator de Crescimento Semelhante a EGF de Ligação à Heparina/metabolismo , Humanos , Células Secretoras de Insulina/efeitos dos fármacos , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/metabolismo , RNA Mensageiro/metabolismo , Ratos , Transdução de Sinais , Quinases da Família src/antagonistas & inibidores
19.
Mol Cell Endocrinol ; 499: 110584, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31539596

RESUMO

Peptidase-resistant analogues of GLP-1 peptides from sea lamprey and paddlefish ([D-Ala2]palmitoyl-lamprey GLP-1 and [D-Ala2]palmitoyl-paddlefish GLP-1) produced significant (P ≤ 0.05) and concentration-dependent increases in insulin release from BRIN-BD11 clonal ß-cells and from isolated mouse islets. Both analogues retained the ability of the native peptides to activate both the GLP-1 receptor (GLP1R) and the glucagon receptor (GCGR). [D-Ala2]palmitoyl-lamprey GLP-1 significantly (P < 0.001) stimulated proliferation of BRIN-BD11 cells and protected against cytokine-induced apoptosis. Administration of the lamprey analogue (25 nmol/kg body weight) to lean mice up to 4 h before a glucose load improved glucose tolerance and increased plasma insulin concentrations. Twice daily administration of the lamprey GLP-1 analogue to high fat-fed mice for 21 days decreased body weight, food intake, and circulating glucose and insulin concentrations. The analogue significantly improved glucose tolerance and insulin sensitivity with beneficial effects on islet ß-cell area and insulin secretory responsiveness. Islet gene expression of Glp1r, Gcgr and Gipr significantly increased. The lamprey GLP-1 analogue shows therapeutic promise for treatment of patients with obesity-related Type 2 diabetes.


Assuntos
Glicemia/efeitos dos fármacos , Dieta Hiperlipídica/efeitos adversos , Peptídeo 1 Semelhante ao Glucagon/análogos & derivados , Incretinas/administração & dosagem , Ilhotas Pancreáticas/metabolismo , Lampreias/metabolismo , Animais , Peso Corporal/efeitos dos fármacos , Células Cultivadas , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Ingestão de Alimentos/efeitos dos fármacos , Proteínas de Peixes/química , Peptídeo 1 Semelhante ao Glucagon/química , Receptor do Peptídeo Semelhante ao Glucagon 1/metabolismo , Incretinas/química , Incretinas/farmacologia , Insulina/sangue , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/metabolismo , Ilhotas Pancreáticas/citologia , Ilhotas Pancreáticas/efeitos dos fármacos , Camundongos , Receptores de Glucagon/metabolismo
20.
Biochem Biophys Res Commun ; 523(2): 382-388, 2020 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-31866014

RESUMO

Hypoxia affects the function of pancreatic ß cells, and the molecular mechanism underlying hypoxia-related ß cell dysfunction in human type 2 diabetes mellitus (T2DM) remains to be elucidated. In this study, by comparing the gene expression profiles of islets from nondiabetic and T2D subjects using gene chip array, we aimed to elucidate that hypoxia signaling pathways are activated in human T2DM islets. CoCl2 treatment, which was employed to mimic hypoxic stimulation in human islets, decreased insulin secretion, insulin content, and the functional gene expression of human islets. In parallel, the expression of mature ß cell-disallowed genes was upregulated by CoCl2, including progenitor cell marker NGN3, ß cell differentiation marker ALDH1A3, and genes that are typically inhibited in mature ß cells, namely, GLUT1 and LDHA, indicating that CoCl2-mimicked hypoxia induced ß cell dedifferentiation of human islets. This finding in human islets was confirmed in mouse ß cell line NIT-1. By using Dimethyloxalylglycine (DMOG) to activate hypoxia-inducible factor-1α (HIF-1α) or siRNAs to knockdown HIF-1α, we found that HIF-1α was a key regulator of hypoxia-induced dedifferentiation of ß cells by upregulating mature ß cell-disallowed genes. Our findings suggested that HIF-1α activation might be an important contributor to ß cell dedifferentiation in human T2DM islets, and HIF-1α-targeted therapies may have the potential to reverse ß cell dedifferentiation of human T2DM islets.


Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patologia , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/metabolismo , Animais , Desdiferenciação Celular/efeitos dos fármacos , Desdiferenciação Celular/genética , Hipóxia Celular/efeitos dos fármacos , Hipóxia Celular/genética , Linhagem Celular , Cobalto/toxicidade , Diabetes Mellitus Tipo 2/genética , Expressão Gênica , Técnicas de Silenciamento de Genes , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/antagonistas & inibidores , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Células Secretoras de Insulina/efeitos dos fármacos , Ilhotas Pancreáticas/citologia , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/metabolismo , Camundongos , Transdução de Sinais
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