Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 42
Filtrar
1.
Diabetologia ; 2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38864887

RESUMO

AIMS/HYPOTHESIS: Insulitis, a hallmark of inflammation preceding autoimmune type 1 diabetes, leads to the eventual loss of functional beta cells. However, functional beta cells can persist even in the face of continuous insulitis. Despite advances in immunosuppressive treatments, maintaining functional beta cells to prevent insulitis progression and hyperglycaemia remains a challenge. The cannabinoid type 1 receptor (CB1R), present in immune cells and beta cells, regulates inflammation and beta cell function. Here, we pioneer an ex vivo model mirroring human insulitis to investigate the role of CB1R in this process. METHODS: CD4+ T lymphocytes were isolated from peripheral blood mononuclear cells (PBMCs) from male and female individuals at the onset of type 1 diabetes and from non-diabetic individuals, RNA was extracted and mRNA expression was analysed by real-time PCR. Single beta cell expression from donors with type 1 diabetes was obtained from data mining. Patient-derived human islets from male and female cadaveric donors were 3D-cultured in solubilised extracellular matrix gel in co-culture with the same donor PBMCs, and incubated with cytokines (IL-1ß, TNF-α, IFN-γ) for 24-48 h in the presence of vehicle or increasing concentrations of the CB1R blocker JD-5037. Expression of CNR1 (encoding for CB1R) was ablated using CRISPR/Cas9 technology. Viability, intracellular stress and signalling were assayed by live-cell probing and real-time PCR. The islet function measured as glucose-stimulated insulin secretion was determined in a perifusion system. Infiltration of immune cells into the islets was monitored by microscopy. Non-obese diabetic mice aged 7 weeks were treated for 1 week with JD-5037, then euthanised. Profiling of immune cells infiltrated in the islets was performed by flow cytometry. RESULTS: CNR1 expression was upregulated in circulating CD4+ T cells from individuals at type 1 diabetes onset (6.9-fold higher vs healthy individuals) and in sorted islet beta cells from donors with type 1 diabetes (3.6-fold higher vs healthy counterparts). The peripherally restricted CB1R inverse agonist JD-5037 arrested the initiation of insulitis in humans and mice. Mechanistically, CB1R blockade prevented islet NO production and ameliorated the ATF6 arm of the unfolded protein response. Consequently, cyto/chemokine expression decreased in human islets, leading to sustained islet cell viability and function. CONCLUSIONS/INTERPRETATION: These results suggest that CB1R could be an interesting target for type 1 diabetes while highlighting the regulatory mechanisms of insulitis. Moreover, these findings may apply to type 2 diabetes where islet inflammation is also a pathophysiological factor. DATA AVAILABILITY: Transcriptomic analysis of sorted human beta cells are from Gene Expression Omnibus database, accession no. GSE121863, available at https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSM3448161 .

2.
Cell Rep ; 43(4): 114047, 2024 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-38607916

RESUMO

Using 13C6 glucose labeling coupled to gas chromatography-mass spectrometry and 2D 1H-13C heteronuclear single quantum coherence NMR spectroscopy, we have obtained a comparative high-resolution map of glucose fate underpinning ß cell function. In both mouse and human islets, the contribution of glucose to the tricarboxylic acid (TCA) cycle is similar. Pyruvate fueling of the TCA cycle is primarily mediated by the activity of pyruvate dehydrogenase, with lower flux through pyruvate carboxylase. While the conversion of pyruvate to lactate by lactate dehydrogenase (LDH) can be detected in islets of both species, lactate accumulation is 6-fold higher in human islets. Human islets express LDH, with low-moderate LDHA expression and ß cell-specific LDHB expression. LDHB inhibition amplifies LDHA-dependent lactate generation in mouse and human ß cells and increases basal insulin release. Lastly, cis-instrument Mendelian randomization shows that low LDHB expression levels correlate with elevated fasting insulin in humans. Thus, LDHB limits lactate generation in ß cells to maintain appropriate insulin release.


Assuntos
Secreção de Insulina , Células Secretoras de Insulina , L-Lactato Desidrogenase , Ácido Láctico , Humanos , Células Secretoras de Insulina/metabolismo , Animais , L-Lactato Desidrogenase/metabolismo , Camundongos , Ácido Láctico/metabolismo , Glucose/metabolismo , Insulina/metabolismo , Isoenzimas/metabolismo , Ciclo do Ácido Cítrico , Camundongos Endogâmicos C57BL , Masculino
3.
Nat Commun ; 15(1): 1879, 2024 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-38424041

RESUMO

Cancer cells integrate multiple biosynthetic demands to drive unrestricted proliferation. How these cellular processes crosstalk to fuel cancer cell growth is still not fully understood. Here, we uncover the mechanisms by which the transcription factor Carbohydrate responsive element binding protein (ChREBP) functions as an oncogene during hepatocellular carcinoma (HCC) development. Mechanistically, ChREBP triggers the expression of the PI3K regulatory subunit p85α, to sustain the activity of the pro-oncogenic PI3K/AKT signaling pathway in HCC. In parallel, increased ChREBP activity reroutes glucose and glutamine metabolic fluxes into fatty acid and nucleic acid synthesis to support PI3K/AKT-mediated HCC growth. Thus, HCC cells have a ChREBP-driven circuitry that ensures balanced coordination between PI3K/AKT signaling and appropriate cell anabolism to support HCC development. Finally, pharmacological inhibition of ChREBP by SBI-993 significantly suppresses in vivo HCC tumor growth. Overall, we show that targeting ChREBP with specific inhibitors provides an attractive therapeutic window for HCC treatment.


Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Humanos , Carcinoma Hepatocelular/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Neoplasias Hepáticas/metabolismo , Transdução de Sinais , Carcinogênese , Proliferação de Células , Linhagem Celular Tumoral
4.
iScience ; 26(4): 106057, 2023 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-36942050

RESUMO

Metformin (MET) is the most prescribed antidiabetic drug, but its mechanisms of action remain elusive. Recent data point to the gut as MET's primary target. Here, we explored the effect of MET on the gut glucose transport machinery. Using human enterocytes (Caco-2/TC7 cells) in vitro, we showed that MET transiently reduced the apical density of sodium-glucose transporter 1 (SGLT1) and decreased the absorption of glucose, without changes in the mRNA levels of the transporter. Administered 1 h before a glucose challenge in rats (Wistar, GK), C57BL6 mice and mice pigs, oral MET reduced the post-prandial glucose response (PGR). This effect was abrogated in SGLT1-KO mice. MET also reduced the luminal clearance of 2-(18F)-fluoro-2-deoxy-D-glucose after oral administration in rats. In conclusion, oral metformin transiently lowers post-prandial glucose response by reducing the apical expression of SGLT1 in enterocytes, which may contribute to the clinical effects of the drug.

5.
Transpl Int ; 36: 11950, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38213551

RESUMO

In islet transplantation (ITx), primary graft function (PGF) or beta cell function measured early after last infusion is closely associated with long term clinical outcomes. We investigated the association between PGF and 5 year insulin independence rate in ITx and pancreas transplantation (PTx) recipients. This retrospective multicenter study included type 1 diabetes patients who underwent ITx in Lille and PTx in Nantes from 2000 to 2022. PGF was assessed using the validated Beta2-score and compared to normoglycemic control subjects. Subsequently, the 5 year insulin independence rates, as predicted by a validated PGF-based model, were compared to the actual rates observed in ITx and PTx patients. The study enrolled 39 ITx (23 ITA, 16 IAK), 209 PTx recipients (23 PTA, 14 PAK, 172 SPK), and 56 normoglycemic controls. Mean[SD] PGF was lower after ITx (ITA 22.3[5.2], IAK 24.8[6.4], than after PTx (PTA 38.9[15.3], PAK 36.8[9.0], SPK 38.7[10.5]), and lower than mean beta-cell function measured in normoglycemic control: 36.6[4.3]. The insulin independence rates observed at 5 years after PTA and PAK aligned with PGF predictions, and was higher after SPK. Our results indicate a similar relation between PGF and 5 year insulin independence in ITx and solitary PTx, shedding new light on long-term transplantation outcomes.


Assuntos
Diabetes Mellitus Tipo 1 , Transplante das Ilhotas Pancreáticas , Transplante de Pâncreas , Humanos , Diabetes Mellitus Tipo 1/cirurgia , Estudos Retrospectivos , Estudos de Coortes , Insulina/uso terapêutico , Transplante de Pâncreas/métodos , Pâncreas , Sobrevivência de Enxerto
6.
Cell Metab ; 34(7): 1054-1063.e7, 2022 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-35716660

RESUMO

Liraglutide, an anti-diabetic drug and agonist of the glucagon-like peptide one receptor (GLP1R), has recently been approved to treat obesity in individuals with or without type 2 diabetes. Despite its extensive metabolic benefits, the mechanism and site of action of liraglutide remain unclear. Here, we demonstrate that liraglutide is shuttled to target cells in the mouse hypothalamus by specialized ependymoglial cells called tanycytes, bypassing the blood-brain barrier. Selectively silencing GLP1R in tanycytes or inhibiting tanycytic transcytosis by botulinum neurotoxin expression not only hampers liraglutide transport into the brain and its activation of target hypothalamic neurons, but also blocks its anti-obesity effects on food intake, body weight and fat mass, and fatty acid oxidation. Collectively, these striking data indicate that the liraglutide-induced activation of hypothalamic neurons and its downstream metabolic effects are mediated by its tanycytic transport into the mediobasal hypothalamus, strengthening the notion of tanycytes as key regulators of metabolic homeostasis.


Assuntos
Diabetes Mellitus Tipo 2 , Liraglutida , Animais , Barreira Hematoencefálica , Diabetes Mellitus Tipo 2/metabolismo , Células Ependimogliais , Hipotálamo/metabolismo , Liraglutida/farmacologia , Camundongos , Obesidade/tratamento farmacológico , Obesidade/metabolismo
8.
Front Cell Dev Biol ; 8: 590763, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33240888

RESUMO

Rat insulinoma INS-1 cells are widely used to study insulin secretory mechanisms. Studies have shown that a population of INS-1 cells are bi-hormonal, co-expressing insulin, and proglucagon proteins. They coined this population as immature cells since they co-secrete proglucagon-derived peptides from the same secretory vesicles similar to that of insulin. Since proglucagon encodes multiple peptides including glucagon, glucagon-like-peptide-1 (GLP-1), GLP-2, oxyntomodulin, and glicentin, their specific expression and secretion are technically challenging. In this study, we aimed to focus on glucagon expression which shares the same amino acid sequence with glicentin and proglucagon. Validation of the anti-glucagon antibody (Abcam) by Western blotting techniques revealed that the antibody detects proglucagon (≈ 20 kDa), glicentin (≈ 9 kDa), and glucagon (≈ 3 kDa) in INS-1 cells and primary islets, all of which were absent in the kidney cell line (HEK293). Using the validated anti-glucagon antibody, we showed by immunofluorescence imaging that a population of INS-1 cells co-express insulin and proglucagon-derived proteins. Furthermore, we found that chronic treatment of INS-1 cells with high-glucose decreases insulin and glucagon content, and also reduces the percentage of bi-hormonal cells. In line with insulin secretion, we found glucagon and glicentin secretion to be induced in a glucose-dependent manner. We conclude that INS-1 cells are a useful model to study glucose-stimulated insulin secretion, but not that of glucagon or glicentin. Our study suggests Western blotting technique as an important tool for researchers to study proglucagon-derived peptides expression and regulation in primary islets in response to various metabolic stimuli.

9.
Diabetes ; 69(5): 902-914, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31896553

RESUMO

Studies implicating sodium-glucose cotransporter 2 (SGLT2) inhibitors in glucagon secretion by pancreatic α-cells reported controversial results. We hypothesized that interindividual heterogeneity in SGLT2 expression and regulation may affect glucagon secretion by human α-cells in response to SGLT2 inhibitors. An unbiased RNA-sequencing analysis of 207 donors revealed an unprecedented level of heterogeneity of SLC5A2 expression. To determine heterogeneity of SGLT2 expression at the protein level, the anti-SGLT2 antibody was first rigorously evaluated for specificity, followed by Western blot and immunofluorescence analysis on islets from 10 and 12 donors, respectively. The results revealed a high interdonor variability of SGLT2 protein expression. Quantitative analysis of 665 human islets showed a significant SGLT2 protein colocalization with glucagon but not with insulin or somatostatin. Moreover, glucagon secretion by islets from 31 donors at low glucose (1 mmol/L) was also heterogeneous and correlated with dapagliflozin-induced glucagon secretion at 6 mmol/L glucose. Intriguingly, islets from three donors did not secrete glucagon in response to either 1 mmol/L glucose or dapagliflozin, indicating a functional impairment of the islets of these donors to glucose sensing and SGLT2 inhibition. Collectively, these data suggest that heterogeneous expression of SGLT2 protein and variability in glucagon secretory responses contribute to interindividual differences in response to SGLT2 inhibitors.


Assuntos
Compostos Benzidrílicos/farmacologia , Glucosídeos/farmacologia , Ilhotas Pancreáticas/metabolismo , Transportador 2 de Glucose-Sódio/metabolismo , Anticorpos , Glicemia , Bases de Dados de Ácidos Nucleicos , Glucagon/metabolismo , Glucose/administração & dosagem , Glucose/farmacologia , Células HEK293 , Humanos , RNA Interferente Pequeno , Transportador 2 de Glucose-Sódio/genética , Transportador 2 de Glucose-Sódio/imunologia , Inibidores do Transportador 2 de Sódio-Glicose/farmacologia
11.
Cell Rep ; 28(6): 1447-1454.e4, 2019 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-31390560

RESUMO

The newest classes of anti-diabetic agents include sodium-glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide 1 receptor (GLP1R) agonists. The SGLT2 inhibitor dapagliflozin reduces glucotoxicity by glycosuria but elevates glucagon secretion. The GLP1R agonist liraglutide inhibits glucagon; therefore, we hypothesize that the cotreatment of dapagliflozin with liraglutide could reduce hyperglucagonemia and hyperglycemia. Here we use five complementary models: human islet cultures, healthy mice, db/db mice, diet-induced obese (DIO) mice, and somatostatin receptor-2 (SSTR2) KO mice. A single administration of liraglutide and dapagliflozin in combination improves glycemia and reduces dapagliflozin-induced glucagon secretion in diabetic mice. Chronic treatment with liraglutide and dapagliflozin produces a sustainable reduction of glycemia compared with each drug alone. Moreover, liraglutide reduces dapagliflozin-induced glucagon secretion by enhancing somatostatin release, as demonstrated by SSTR2 inhibition in human islets and in mice. Collectively, these data provide mechanistic insights into how intra-islet GLP1R activation is critical for the regulation of glucose homeostasis.


Assuntos
Compostos Benzidrílicos/efeitos adversos , Diabetes Mellitus Experimental/tratamento farmacológico , Glucagon/efeitos dos fármacos , Glucosídeos/efeitos adversos , Liraglutida/uso terapêutico , Somatostatina/efeitos dos fármacos , Animais , Humanos , Liraglutida/farmacologia , Masculino , Camundongos
12.
Artigo em Inglês | MEDLINE | ID: mdl-31164864

RESUMO

Thioredoxin interacting protein (TxNIP), which strongly responds to glucose, has emerged as a central mediator of glucotoxicity in pancreatic ß cells. TxNIP is a scaffold protein interacting with target proteins to inhibit or stimulate their activity. Recent studies reported that high glucose stimulates the interaction of TxNIP with the inflammasome protein NLRP3 (NLR family, pyrin domain containing 3) to increase interleukin-1 ß (IL1ß) secretion by pancreatic ß cells. To better understand the regulation of TxNIP by glucose in pancreatic ß cells, we investigated the implication of O-linked ß-N-acetylglucosamine (O-GlcNAcylation) in regulating TxNIP at the posttranslational level. O-GlcNAcylation of proteins is controlled by two enzymes: the O-GlcNAc transferase (OGT), which transfers a monosaccharide to serine/threonine residues on target proteins, and the O-GlcNAcase (OGA), which removes it. Our study shows that TxNIP is subjected to O-GlcNAcylation in response to high glucose concentrations in ß cell lines. Modification of the O-GlcNAcylation pathway through manipulation of OGT or OGA expression or activity significantly modulates TxNIP O-GlcNAcylation in INS1 832/13 cells. Interestingly, expression and O-GlcNAcylation of TxNIP appeared to be increased in islets of diabetic rodents. At the mechanistic level, the induction of the O-GlcNAcylation pathway in human and rat islets promotes inflammasome activation as evidenced by enhanced cleaved IL1ß. Overexpression of OGT in HEK293 or INS1 832/13 cells stimulates TxNIP and NLRP3 interaction, while reducing TxNIP O-GlcNAcylation through OGA overexpression destabilizes this interaction. Altogether, our study reveals that O-GlcNAcylation represents an important regulatory mechanism for TxNIP activity in ß cells.

13.
Transplantation ; 103(1): 177-181, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30113997

RESUMO

BACKGROUND: Total pancreatectomy with intraportal islet autotransplantation (TPIAT) rather than partial pancreatectomy could represent a major shift in the management of patients with resectable pancreatic ductal adenocarcinoma (PDAC) when risks of postoperative pancreatic fistula are well identified. This approach provides a theoretical risk of tumor cell dissemination when islet cells are transplanted into the portal vein. Our objective was to explore the safety of TPIAT in PDAC in a mouse preclinical model of subcutaneous xenotransplantation of human cells isolated from pancreatic specimen during partial pancreatectomy performed for PDAC. METHODS: Patients requiring pancreatectomy for PDAC were prospectively included. Immunocompromised mice were transplanted with pancreatic cells isolated from the nonmalignant part of the surgical specimen (experimental group). Results were compared with pancreatic tumor implants (control group). Pancreatic grafts were explanted at 6 weeks for histological analyses. RESULTS: Nine patients were included, and 31 mice were transplanted. In the experimental group, explants were microscopically devoid of tumor cell, and no metastasis was observed. In the control group, all explants were composed of tumor. CONCLUSIONS: We report in a preclinical model the absence of local and distant spreading of malignant cells after pancreatic islets xenograft isolated from PDAC patients. These data supports the oncological safety of TPIAT as valuable alternative to partial pancreatectomy for PDAC patients with a high risk of postoperative pancreatic fistula.


Assuntos
Carcinoma Ductal Pancreático/cirurgia , Transplante das Ilhotas Pancreáticas , Pancreatectomia , Neoplasias Pancreáticas/cirurgia , Pancreaticoduodenectomia , Idoso , Animais , Carcinoma Ductal Pancreático/patologia , Feminino , Humanos , Transplante das Ilhotas Pancreáticas/efeitos adversos , Masculino , Camundongos Nus , Pessoa de Meia-Idade , Neoplasias Pancreáticas/patologia , Estudos Prospectivos , Medição de Risco , Fatores de Tempo , Transplante Autólogo , Transplante Heterólogo
14.
Shock ; 52(4): e60-e67, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-30325871

RESUMO

BACKGROUND: Antithrombin (AT) III physiological levels are decreased during septic shock and supplementation therapy could therefore be beneficial. OBJECTIVE: We hypothesized that the use of recombinant human AT could reduce disseminated intravascular coagulation (DIC) occurrence. METHODS: We conducted a randomized open label controlled experimental study. Ten female "Large White" pigs were challenged with i.v. infusion of Escherichia coli endotoxin. Two groups of 5 pigs were randomly assigned to receive either recombinant human AT 100 U/kg over 30 min (ATryn group) or 0.9% saline (control group). AT III levels, coagulation, hemostasis, inflammation parameters, hemodynamics, and microcirculatory parameters were measured over a 5-h period. Immediately after euthanasia, kidneys were withdrawn for histology evaluation. Statistical analysis was performed with nonparametric tests and Dunn's test for multiple comparisons. RESULTS: AT III activity was significantly higher in the ATryn group than in the control group from 60% (213% [203-223] vs. 104% [98-115], P = 0.008, respectively) to 300 min (115% [95-124] vs. 79% [67-93], P = 0.03). Recombinant human AT supplementation had no impact on hemodynamics, microcirculatory parameters, and sequential changes of coagulation parameters (platelet count, fibrinogen level, thrombin-AT complexes, and von Willebrand factor). Interleukin 6 and tumor necrosis factor α values were statistically the same for both groups throughout the study. Percentage of thrombosed glomeruli and percentage of thrombosed capillary in glomerulus were not significantly different between both groups. CONCLUSIONS: In our model of endotoxic shock, a single low dose of recombinant human AT did not prevent DIC occurrence, severity, inflammatory profile, or hemodynamic alterations.


Assuntos
Antitrombina III , Coagulação Intravascular Disseminada , Endotoxinas , Choque Séptico , Animais , Humanos , Antitrombina III/farmacologia , Modelos Animais de Doenças , Coagulação Intravascular Disseminada/sangue , Coagulação Intravascular Disseminada/induzido quimicamente , Coagulação Intravascular Disseminada/tratamento farmacológico , Endotoxinas/química , Endotoxinas/toxicidade , Escherichia coli/química , Proteínas Recombinantes/farmacologia , Choque Séptico/sangue , Choque Séptico/induzido quimicamente , Choque Séptico/tratamento farmacológico , Suínos
15.
Mol Metab ; 11: 104-112, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29526568

RESUMO

OBJECTIVE: Aberrant hepatic glucose production contributes to the development of hyperglycemia and is a hallmark of type 2 diabetes. In a recent study, we showed that the transcription factor E2F1, a component of the cell cycle machinery, contributes to hepatic steatosis through the transcriptional regulation of key lipogenic enzymes. Here, we investigate if E2F1 contributes to hyperglycemia by regulating hepatic gluconeogenesis. METHODS: We use different genetic models to investigate if E2F1 regulates gluconeogenesis in primary hepatocytes and in vivo. We study the impact of depleting E2F1 or inhibiting E2F1 activity in diabetic mouse models to evaluate if this transcription factor contributes to hyperglycemia during insulin resistance. We analyze E2F1 mRNA levels in the livers of human diabetic patients to assess the relevance of E2F1 in human pathophysiology. RESULTS: Lack of E2F1 impaired gluconeogenesis in primary hepatocytes. Conversely, E2F1 overexpression increased glucose production in hepatocytes and in mice. Several genetic models showed that the canonical CDK4-RB1-E2F1 pathway is directly involved in this regulation. E2F1 mRNA levels were increased in the livers from human diabetic patients and correlated with the expression of the gluconeogenic enzyme Pck1. Genetic invalidation or pharmacological inhibition of E2F1 improved glucose homeostasis in diabetic mouse models. CONCLUSIONS: Our study unveils that the transcription factor E2F1 contributes to mammalian glucose homeostasis by directly controlling hepatic gluconeogenesis. Together with our previous finding that E2F1 promotes hepatic steatosis, the data presented here show that E2F1 contributes to both hyperlipidemia and hyperglycemia in diabetes, suggesting that specifically targeting E2F1 in the liver could be an interesting strategy for therapies against type 2 diabetes.


Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Fator de Transcrição E2F1/metabolismo , Gluconeogênese , Hiperglicemia/metabolismo , Animais , Células Cultivadas , Fator de Transcrição E2F1/genética , Células Hep G2 , Humanos , Fígado/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Transdução de Sinais
17.
Cell Metab ; 25(2): 400-411, 2017 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-28041957

RESUMO

Recent studies have uncovered thousands of long non-coding RNAs (lncRNAs) in human pancreatic ß cells. ß cell lncRNAs are often cell type specific and exhibit dynamic regulation during differentiation or upon changing glucose concentrations. Although these features hint at a role of lncRNAs in ß cell gene regulation and diabetes, the function of ß cell lncRNAs remains largely unknown. In this study, we investigated the function of ß cell-specific lncRNAs and transcription factors using transcript knockdowns and co-expression network analysis. This revealed lncRNAs that function in concert with transcription factors to regulate ß cell-specific transcriptional networks. We further demonstrate that the lncRNA PLUTO affects local 3D chromatin structure and transcription of PDX1, encoding a key ß cell transcription factor, and that both PLUTO and PDX1 are downregulated in islets from donors with type 2 diabetes or impaired glucose tolerance. These results implicate lncRNAs in the regulation of ß cell-specific transcription factor networks.


Assuntos
Redes Reguladoras de Genes/genética , Células Secretoras de Insulina/metabolismo , RNA Longo não Codificante/genética , Cromatina/metabolismo , Diabetes Mellitus Tipo 2/genética , Regulação da Expressão Gênica , Técnicas de Silenciamento de Genes , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Humanos , Insulina/metabolismo , Secreção de Insulina , Família Multigênica , Fenótipo , RNA Longo não Codificante/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Transativadores/genética , Transativadores/metabolismo , Fatores de Transcrição/metabolismo , Transcrição Gênica
18.
Cell Transplant ; 26(2): 309-317, 2017 02 16.
Artigo em Inglês | MEDLINE | ID: mdl-27938471

RESUMO

Human islet transplantation is a viable treatment option for type 1 diabetes mellitus (T1DM). However, pancreatic islet inflammation after transplantation induced by innate immune responses is likely to hinder graft function. This is mediated by incompatibility between islets and the blood interface, known as instant blood-mediated inflammatory reaction (IBMIR). Herein we hypothesized that portal venous administration of islet cells with human recombinant antithrombin (ATryn®), a serine protease inhibitor (serpin), which plays a central role in the physiological regulation of coagulation and exerts indirect anti-inflammatory activities, may offset coagulation abnormalities such as disseminated intravascular coagulation (DIC) and IBMIR. The current prospective, randomized experiment was conducted using an established preclinical pig model. Three groups were constituted for digested pancreatic tissue transplantation (0.15 ml/kg): control, NaCl 0.9% (n = 7); gold standard, heparin (25 UI/kg) (n = 7); and human recombinant ATryn® (500 UI/kg) (n = 7). Blood samples were collected over time (T0 to 24 h), and biochemical, coagulation, and inflammatory parameters were evaluated. In both the control and heparin groups, one animal died after a portal thrombosis, while no deaths occurred in the ATryn®-treated group. As expected, islet transplantation was associated with an increase in plasma IL-6 or TNF-α levels in all three groups. However, DIC was only observed in the control group, an effect that was suppressed after ATryn® administration. ATryn® administration increased antithrombin activity by 800%, which remained at 200% for the remaining period of the study, without any hemorrhagic complications. These studies suggest that coadministration of ATryn® and pancreatic islets via intraportal transplantation may be a valuable therapeutic approach for DIC without risk for islets and subjects.


Assuntos
Antitrombina III/uso terapêutico , Transplante das Ilhotas Pancreáticas/métodos , Ilhotas Pancreáticas/efeitos dos fármacos , Animais , Sobrevivência Celular/efeitos dos fármacos , Feminino , Sobrevivência de Enxerto/efeitos dos fármacos , Sobrevivência de Enxerto/imunologia , Interleucina-6/metabolismo , Ilhotas Pancreáticas/imunologia , Ilhotas Pancreáticas/metabolismo , Transplante das Ilhotas Pancreáticas/imunologia , Estimativa de Kaplan-Meier , Estudos Prospectivos , Distribuição Aleatória , Suínos , Fator de Necrose Tumoral alfa/metabolismo
19.
PLoS One ; 11(9): e0163046, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27636901

RESUMO

Elevated plasma concentration of the pro-atherogenic oxidized low density lipoprotein cholesterol (LDL) triggers adverse effects in pancreatic beta-cells and is associated with type 2 diabetes. Here, we investigated whether the endoplasmic reticulum (ER) stress is a key player coupling oxidative stress to beta-cell dysfunction and death elicited by human oxidized LDL. We found that human oxidized LDL activates ER stress as evidenced by the activation of the inositol requiring 1α, and the elevated expression of both DDIT3 (also called CHOP) and DNAJC3 (also called P58IPK) ER stress markers in isolated human islets and the mouse insulin secreting MIN6 cells. Silencing of Chop and inhibition of ER stress markers by the chemical chaperone phenyl butyric acid (PBA) prevented cell death caused by oxidized LDL. Finally, we found that oxidative stress accounts for activation of ER stress markers induced by oxidized LDL. Induction of Chop/CHOP and p58IPK/P58IPK by oxidized LDL was mimicked by hydrogen peroxide and was blocked by co-treatment with the N-acetylcystein antioxidant. As a conclusion, the harmful effects of oxidized LDL in beta-cells requires ER stress activation in a manner that involves oxidative stress. This mechanism may account for impaired beta-cell function in diabetes and can be reversed by antioxidant treatment.


Assuntos
Estresse do Retículo Endoplasmático , Ilhotas Pancreáticas/fisiopatologia , Lipoproteínas LDL/fisiologia , Estresse Oxidativo , Acetilcisteína/administração & dosagem , Fator 6 Ativador da Transcrição/metabolismo , Animais , Antioxidantes/administração & dosagem , Apoptose , Biomarcadores/metabolismo , Linhagem Celular , Endorribonucleases/metabolismo , Humanos , Peróxido de Hidrogênio/administração & dosagem , Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/patologia , Camundongos , Proteínas Serina-Treonina Quinases/metabolismo
20.
Surg Obes Relat Dis ; 12(6): 1206-12, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27320223

RESUMO

Active sodium-glucose transporters play a role to glucose homeostasis and represent novels targets for the management of type 2 diabetes (T2D). Sodium-glucose cotransporter 1 (SGLT1) is essential for intestinal glucose absorption from the lumen into enterocytes, whereas glucose reabsorption by the kidney is mainly mediated by sodium-glucose cotransporter 2 (SGLT2). SGLT2 inhibitors were developed to occlude SGLT2 glucose reabsorption pathway and cause glycosuria, thereby reducing plasma glucose concentrations. This new class of antidiabetic drugs has been shown to be effective in reducing cardiovascular morbidity and mortality in patients with T2D. Initial clinical studies also suggest that SGLT1 inhibition increases glucagon-like peptide 1 (GLP-1) secretion and decreases postchallenge blood glucose excursion, resulting in a dose-dependent improvement of glucose control. In parallel, we recently identified a previously unknown effect of bile diversion in gastric bypass on sodium glucose transport and postprandial glucose homeostasis, through the modulation of intestinal trafficking of endogenous sodium. This mechanism is consistent with available clinical evidence, and opens up new perspectives in metabolic surgery. More generally, the modulation of intestinal sodium-glucose cotransport appears to be a promising avenue to prevent or treat T2D.


Assuntos
Glicemia/metabolismo , Diabetes Mellitus Tipo 2/cirurgia , Derivação Gástrica/métodos , Proteínas de Transporte de Sódio-Glucose/fisiologia , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/fisiopatologia , Homeostase/fisiologia , Humanos , Insulina/fisiologia , Mucosa Intestinal/metabolismo , Proteínas de Transporte de Sódio-Glucose/antagonistas & inibidores
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA