Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 49
Filtrar
1.
Cell ; 175(5): 1289-1306.e20, 2018 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-30454647

RESUMO

Obesity is a major driver of cancer, especially hepatocellular carcinoma (HCC). The prevailing view is that non-alcoholic steatohepatitis (NASH) and fibrosis or cirrhosis are required for HCC in obesity. Here, we report that NASH and fibrosis and HCC in obesity can be dissociated. We show that the oxidative hepatic environment in obesity inactivates the STAT-1 and STAT-3 phosphatase T cell protein tyrosine phosphatase (TCPTP) and increases STAT-1 and STAT-3 signaling. TCPTP deletion in hepatocytes promoted T cell recruitment and ensuing NASH and fibrosis as well as HCC in obese C57BL/6 mice that normally do not develop NASH and fibrosis or HCC. Attenuating the enhanced STAT-1 signaling prevented T cell recruitment and NASH and fibrosis but did not prevent HCC. By contrast, correcting STAT-3 signaling prevented HCC without affecting NASH and fibrosis. TCPTP-deletion in hepatocytes also markedly accelerated HCC in mice treated with a chemical carcinogen that promotes HCC without NASH and fibrosis. Our studies reveal how obesity-associated hepatic oxidative stress can independently contribute to the pathogenesis of NASH, fibrosis, and HCC.


Assuntos
Carcinoma Hepatocelular/patologia , Neoplasias Hepáticas/patologia , Hepatopatia Gordurosa não Alcoólica/patologia , Obesidade/patologia , Fator de Transcrição STAT1/metabolismo , Fator de Transcrição STAT3/metabolismo , Animais , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/metabolismo , Carcinoma Hepatocelular/metabolismo , Dieta Hiperlipídica , Modelos Animais de Doenças , Hepatócitos/metabolismo , Humanos , Fígado/metabolismo , Fígado/patologia , Cirrose Hepática/metabolismo , Cirrose Hepática/patologia , Neoplasias Hepáticas/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Hepatopatia Gordurosa não Alcoólica/metabolismo , Obesidade/metabolismo , Estresse Oxidativo , Proteína Tirosina Fosfatase não Receptora Tipo 2/deficiência , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética , Proteína Tirosina Fosfatase não Receptora Tipo 2/metabolismo , Transdução de Sinais
2.
Mol Pharm ; 18(12): 4428-4436, 2021 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-34649437

RESUMO

Type 1 diabetes develops in childhood and adolescence, with peak incidence in the early teenage years. There is an urgent need for an accurate method to detect insulin-producing ß-cells in patients that is not affected by alterations in ß-cell function. As part of our research program to design specific probes to measure ß-cell mass, we recently developed a novel insulin-binding peptide probe (IBPP) for the detection of ß-cells in vivo. Here, we applied our innovative method to show specific labeling of this IBPP to human and mouse fixed ß-cells in pancreatic islets. Importantly, we showed staining of human and mouse islets in culture without any negative functional or cell viability impact. Moreover, the IBPP-stained mouse islets after tail vein injection in vivo, albeit with batch differences in staining efficiency. In conclusion, we provide evidence showing that the IBPP can be used for future accurate detection of ß-cell mass in a variety of preclinical models of diabetes.


Assuntos
Diabetes Mellitus Tipo 1/diagnóstico por imagem , Células Secretoras de Insulina/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Animais , Células Cultivadas , Humanos , Insulina/análise , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Confocal , Coloração e Rotulagem
3.
Biomacromolecules ; 18(12): 4249-4260, 2017 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-29035554

RESUMO

Protein aggregation into amyloid fibrils is a ubiquitous phenomenon across the spectrum of neurodegenerative disorders and type 2 diabetes. A common strategy against amyloidogenesis is to minimize the populations of toxic oligomers and protofibrils by inhibiting protein aggregation with small molecules or nanoparticles. However, melanin synthesis in nature is realized by accelerated protein fibrillation to circumvent accumulation of toxic intermediates. Accordingly, we designed and demonstrated the use of star-shaped poly(2-hydroxyethyl acrylate) (PHEA) nanostructures for promoting aggregation while ameliorating the toxicity of human islet amyloid polypeptide (IAPP), the peptide involved in glycemic control and the pathology of type 2 diabetes. The binding of PHEA elevated the ß-sheet content in IAPP aggregates while rendering a new morphology of "stelliform" amyloids originating from the polymers. Atomistic molecular dynamics simulations revealed that the PHEA arms served as rodlike scaffolds for IAPP binding and subsequently accelerated IAPP aggregation by increased local peptide concentration. The tertiary structure of the star nanoparticles was found to be essential for driving the specific interactions required to impel the accelerated IAPP aggregation. This study sheds new light on the structure-toxicity relationship of IAPP and points to the potential of exploiting star polymers as a new class of therapeutic agents against amyloidogenesis.


Assuntos
Amiloide/química , Proteínas Amiloidogênicas/química , Polipeptídeo Amiloide das Ilhotas Pancreáticas/química , Polímeros/química , Agregação Patológica de Proteínas/patologia , Amiloidose/patologia , Animais , Linhagem Celular , Diabetes Mellitus Tipo 2/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Simulação de Dinâmica Molecular , Nanopartículas/química
4.
Small ; 12(12): 1615-26, 2016 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-26808649

RESUMO

Human islet amyloid polypeptide (hIAPP, or amylin) forms amyloid deposits in the islets of Langerhans, a phenomenon that is associated with type-2 diabetes impacting millions of people worldwide. Accordingly, strategies against hIAPP aggregation are essential for the prevention and eventual treatment of the disease. Here, it is shown that generation-3 OH-terminated poly(amidoamine) dendrimer, a polymeric nanoparticle, can effectively halt the aggregation of hIAPP and shut down hIAPP toxicity in pancreatic MIN6 and NIT-1 cells as well as in mouse islets. This finding is supported by high-throughput dynamic light scattering experiment and thioflavin T assay, where the rapid evolution of hIAPP nucleation and elongation processes is halted by the addition of the dendrimer up to 8 h. Discrete molecular dynamics simulations further reveal that hIAPP residues bound strongly with the dendrimer near the c-terminal portion of the peptide, where the amyloidogenic sequence (residues 22-29) locates. Furthermore, simulations of hIAPP dimerization reveal that binding with the dendrimer significantly reduces formation of interpeptide contacts and hydrogen bonds, thereby prohibiting peptide self-association and amyloidosis. This study points to a promising nanomedicinal strategy for combating type-2 diabetes and may have broader implications for targeting neurological disorders whose distinct hallmark is also amyloid fibrillation.


Assuntos
Amiloide/metabolismo , Dendrímeros/toxicidade , Células Secretoras de Insulina/patologia , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Agregados Proteicos/efeitos dos fármacos , Benzotiazóis , Morte Celular/efeitos dos fármacos , Citoproteção/efeitos dos fármacos , Humanos , Hidroxilação , Células Secretoras de Insulina/efeitos dos fármacos , Modelos Moleculares , Multimerização Proteica/efeitos dos fármacos , Tiazóis/metabolismo
5.
Phys Chem Chem Phys ; 18(1): 94-100, 2016 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-26625841

RESUMO

Human islet amyloid polypeptide (hIAPP or amylin) aggregation is directly associated with pancreatic ß-cell death and subsequent insulin deficiency in type 2 diabetes (T2D). Since no cure is currently available for T2D, it is of great benefit to devise new anti-aggregation molecules, which protect ß-cells against hIAPP aggregation-induced toxicity. Engineered nanoparticles have been recently exploited as anti-aggregation nanomedicines. In this work, we studied graphene oxide (GO) nanosheets for their potential for hIAPP aggregation inhibition by combining computational modeling, biophysical characterization and cell toxicity measurements. Using discrete molecular dynamics (DMD) simulations and in vitro studies, we showed that GO exhibited an inhibitory effect on hIAPP aggregation. DMD simulations indicated that the strong binding of hIAPP to GO nanosheets was driven by hydrogen bonding and aromatic stacking and that the strong peptide-GO binding efficiently inhibited hIAPP self-association and aggregation on the nanosheet surface. Secondary structural changes of hIAPP upon GO binding derived from DMD simulations were consistent with circular dichroism (CD) spectroscopy measurements. Transmission electron microscopy (TEM) images confirmed the reduction of hIAPP aggregation in the presence of GO. Furthermore, we carried out a cell toxicity assay and found that these nanosheets protected insulin-secreting NIT-1 pancreatic ß-cells against hIAPP-induced toxicity. Our multidisciplinary study suggests that GO nanosheets have the potential to be utilized as an anti-aggregation nanomedicine itself in addition to a biosensor or delivery vehicle for the mitigation of T2D progression.


Assuntos
Grafite/farmacologia , Células Secretoras de Insulina/efeitos dos fármacos , Insulina/biossíntese , Polipeptídeo Amiloide das Ilhotas Pancreáticas/antagonistas & inibidores , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Óxidos/farmacologia , Agregados Proteicos/efeitos dos fármacos , Linhagem Celular , Grafite/química , Humanos , Células Secretoras de Insulina/metabolismo , Simulação de Dinâmica Molecular , Óxidos/química
6.
STAR Protoc ; 5(3): 103297, 2024 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-39243376

RESUMO

Gene editing of human pluripotent stem cells is a promising approach for developing targeted gene therapies for metabolic diseases. Here, we present a protocol for generating a CRISPR-Cas12a gene knockout of protein tyrosine phosphatases in human embryonic stem cells. We describe steps for differentiating the edited clones into pancreatic islet-like spheroids rich in ß-like cells. We then detail procedures for implanting these spheroids under the murine kidney capsule for in vivo maturation.

7.
iScience ; 27(1): 108694, 2024 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-38213620

RESUMO

An altered gut microbiota is associated with type 1 diabetes (T1D), affecting the production of short-chain fatty acids (SCFA) and glucose homeostasis. We previously demonstrated that enhancing serum acetate and butyrate using a dietary supplement (HAMSAB) improved glycemia in non-obese diabetic (NOD) mice and patients with established T1D. The effects of SCFA on immune-infiltrated islet cells remain to be clarified. Here, we performed single-cell RNA sequencing on islet cells from NOD mice fed an HAMSAB or control diet. HAMSAB induced a regulatory gene expression profile in pancreas-infiltrated immune cells. Moreover, HAMSAB maintained the expression of ß-cell functional genes and decreased cellular stress. HAMSAB-fed mice showed preserved pancreatic endocrine cell identity, evaluated by decreased numbers of poly-hormonal cells. Finally, SCFA increased insulin levels in human ß-like cells and improved transplantation outcome in NOD/SCID mice. Our findings support the use of metabolite-based diet as attractive approach to improve glucose control in T1D.

8.
PLoS Pathog ; 7(9): e1002267, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21977009

RESUMO

The rise in type 1 diabetes (T1D) incidence in recent decades is probably related to modifications in environmental factors. Viruses are among the putative environmental triggers of T1D. The mechanisms regulating beta cell responses to viruses, however, remain to be defined. We have presently clarified the signaling pathways leading to beta cell apoptosis following exposure to the viral mimetic double-stranded RNA (dsRNA) and a diabetogenic enterovirus (Coxsackievirus B5). Internal dsRNA induces cell death via the intrinsic mitochondrial pathway. In this process, activation of the dsRNA-dependent protein kinase (PKR) promotes eIF2α phosphorylation and protein synthesis inhibition, leading to downregulation of the antiapoptotic Bcl-2 protein myeloid cell leukemia sequence 1 (Mcl-1). Mcl-1 decrease results in the release of the BH3-only protein Bim, which activates the mitochondrial pathway of apoptosis. Indeed, Bim knockdown prevented both dsRNA- and Coxsackievirus B5-induced beta cell death, and counteracted the proapoptotic effects of Mcl-1 silencing. These observations indicate that the balance between Mcl-1 and Bim is a key factor regulating beta cell survival during diabetogenic viral infections.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Apoptose , Infecções por Coxsackievirus/metabolismo , Enterovirus Humano B/metabolismo , Células Secretoras de Insulina/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , RNA de Cadeia Dupla/metabolismo , RNA Viral/metabolismo , Animais , Proteína 11 Semelhante a Bcl-2 , Linhagem Celular , Sobrevivência Celular , Infecções por Coxsackievirus/patologia , Diabetes Mellitus Tipo 1/etiologia , Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 1/patologia , Diabetes Mellitus Tipo 1/virologia , Fator de Iniciação 2 em Eucariotos/metabolismo , Humanos , Células Secretoras de Insulina/patologia , Células Secretoras de Insulina/virologia , Masculino , Mitocôndrias/metabolismo , Proteína de Sequência 1 de Leucemia de Células Mieloides , Fosforilação , Ratos , Ratos Wistar
9.
JHEP Rep ; 5(9): 100811, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37575883

RESUMO

Obesity-related complications such as non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes (T2D) are well-established risk factors for the development of hepatocellular carcinoma (HCC). This review provides insights into the molecular mechanisms that underlie the role of steatosis, hyperinsulinemia and hepatic inflammation in HCC development and progression. We focus on recent findings linking intracellular pathways and transcription factors that can trigger the reprogramming of hepatic cells. In addition, we highlight the role of enzymes in dysregulated metabolic activity and consequent dysfunctional signalling. Finally, we discuss the potential uses and challenges of novel therapeutic strategies to prevent and treat NAFLD/T2D-associated HCC.

10.
Mol Metab ; 69: 101681, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36707047

RESUMO

OBJECTIVES: Type 1 diabetes (T1D) is caused by progressive immune-mediated loss of insulin-producing ß-cells. Inflammation is detrimental to ß-cell function and survival, moreover, both apoptosis and necrosis have been implicated as mechanisms of ß-cell loss in T1D. The receptor interacting serine/threonine protein kinase 1 (RIPK1) promotes inflammation by serving as a scaffold for NF-κB and MAPK activation, or by acting as a kinase that triggers apoptosis or necroptosis. It is unclear whether RIPK1 kinase activity is involved in T1D pathology. In the present study, we investigated if absence of RIPK1 activation would affect the susceptibility to immune-mediated diabetes or diet induced obesity (DIO). METHODS: The RIPK1 knockin mouse line carrying a mutation mimicking serine 25 phosphorylation (Ripk1S25D/S25D), which abrogates RIPK1 kinase activity, was utilized to assess the in vivo role of RIPK1 in immune-mediated diabetes or diet induced obesity (DIO). In vitro, ß-cell death and RIPK1 kinase activity was analysed in conditions known to induce RIPK1-dependent apoptosis/necroptosis. RESULTS: We demonstrate that Ripk1S25D/S25D mice presented normal glucose metabolism and ß-cell function. Furthermore, immune-mediated diabetes and DIO were not different between Ripk1S25D/S25D and Ripk1+/+ mice. Despite strong activation of RIPK1 kinase and other necroptosis effectors (RIPK3 and MLKL) by TNF+BV6+zVAD, no cell death was observed in mouse islets nor human ß-cells. CONCLUSION: Our results contrast recent literature showing that most cell types undergo necroptosis following RIPK1 kinase activation. This peculiarity may reflect an adaptation to the inability of ß-cells to proliferate and self-renewal.


Assuntos
Diabetes Mellitus Tipo 1 , Proteínas Quinases , Camundongos , Animais , Humanos , Proteínas Quinases/metabolismo , Inflamação/metabolismo , Serina , Obesidade , Proteína Serina-Treonina Quinases de Interação com Receptores
11.
J Biol Chem ; 286(45): 39632-43, 2011 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-21937453

RESUMO

Type 1 diabetes is characterized by local inflammation (insulitis) in the pancreatic islets causing ß-cell loss. The mitochondrial pathway of apoptosis is regulated by the balance and interaction between Bcl-2 members. Here we clarify the molecular mechanism of ß-cell death triggered by the pro-inflammatory cytokines tumor necrosis factor (TNF)-α and interferon (IFN)-γ. The combination of TNF-α + IFN-γ induced DP5, p53 up-regulated modulator of apoptosis (PUMA), and Bim expression in human islets and rodent ß-cells. DP5 and PUMA inactivation by RNA interference partially protected against TNF-α + IFN-γ-induced ß-cell apoptosis. DP5 knock-out mice had increased ß-cell area, and isolated islets from these mice were resistant to cytokine exposure. Bim expression was transcriptionally regulated by STAT1, and its activation triggered cleavage of caspases. Silencing of Bim protected rodent and human ß-cells to a large extent against TNF-α + IFN-γ, indicating a major role of this BH3-only activator protein in the mechanism of apoptosis. Our data support a highly regulated and context-dependent modulation of specific Bcl-2 members controlling the mitochondrial pathway of ß-cell apoptosis during insulitis.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Apoptose/fisiologia , Células Secretoras de Insulina/metabolismo , Interferon gama/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Fator de Transcrição STAT1/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Adulto , Idoso , Animais , Antivirais/metabolismo , Antivirais/farmacologia , Apoptose/efeitos dos fármacos , Proteínas Reguladoras de Apoptose/genética , Proteína 11 Semelhante a Bcl-2 , Células Cultivadas , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/fisiologia , Inativação Gênica , Humanos , Interferon gama/genética , Interferon gama/farmacologia , Masculino , Proteínas de Membrana/genética , Camundongos , Camundongos Knockout , Pessoa de Meia-Idade , Neuropeptídeos/genética , Neuropeptídeos/metabolismo , Proteínas Proto-Oncogênicas/genética , Fator de Transcrição STAT1/genética , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/farmacologia , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo
12.
J Biol Chem ; 286(2): 929-41, 2011 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-20980260

RESUMO

Cytokines produced by islet-infiltrating immune cells induce ß-cell apoptosis in type 1 diabetes. The IFN-γ-regulated transcription factors STAT1/IRF-1 have apparently divergent effects on ß-cells. Thus, STAT1 promotes apoptosis and inflammation, whereas IRF-1 down-regulates inflammatory mediators. To understand the molecular basis for these differential outcomes within a single signal transduction pathway, we presently characterized the gene networks regulated by STAT1 and IRF-1 in ß-cells. This was done by using siRNA approaches coupled to microarray analysis of insulin-producing cells exposed or not to IL-1ß and IFN-γ. Relevant microarray findings were further studied in INS-1E cells and primary rat ß-cells. STAT1, but not IRF-1, mediates the cytokine-induced loss of the differentiated ß-cell phenotype, as indicated by decreased insulin, Pdx1, MafA, and Glut2. Furthermore, STAT1 regulates cytokine-induced apoptosis via up-regulation of the proapoptotic protein DP5. STAT1 and IRF-1 have opposite effects on cytokine-induced chemokine production, with IRF-1 exerting negative feedback inhibition on STAT1 and downstream chemokine expression. The present study elucidates the transcriptional networks through which the IFN-γ/STAT1/IRF-1 axis controls ß-cell function/differentiation, demise, and islet inflammation.


Assuntos
Apoptose/imunologia , Células Secretoras de Insulina/imunologia , Células Secretoras de Insulina/patologia , Pancreatite/imunologia , Pancreatite/patologia , Fator de Transcrição STAT1/imunologia , Animais , Apoptose/efeitos dos fármacos , Proteínas Reguladoras de Apoptose/genética , Proteínas Reguladoras de Apoptose/imunologia , Diferenciação Celular/imunologia , Células Cultivadas , Retroalimentação Fisiológica/fisiologia , Técnicas de Silenciamento de Genes , Fator Regulador 1 de Interferon/imunologia , Fator Regulador 1 de Interferon/metabolismo , Interferon gama/imunologia , Interferon gama/metabolismo , Interleucina-1beta/farmacologia , Masculino , Neuropeptídeos/genética , Neuropeptídeos/imunologia , RNA Interferente Pequeno , Ratos , Ratos Wistar , Fator de Transcrição STAT1/genética , Fator de Transcrição STAT1/metabolismo , Transcrição Gênica/imunologia
13.
Hum Mol Genet ; 19(1): 135-46, 2010 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-19825843

RESUMO

beta-Cell destruction in type 1 diabetes (T1D) is at least in part consequence of a 'dialog' between beta-cells and immune system. This dialog may be affected by the individual's genetic background. We presently evaluated whether modulation of MDA5 and PTPN2, two candidate genes for T1D, affects beta-cell responses to double-stranded RNA (dsRNA), a by-product of viral replication. These genes were selected following comparison between known candidate genes for T1D and genes expressed in pancreatic beta-cells, as identified in previous array analysis. INS-1E cells and primary fluorescence-activated cell sorting-purified rat beta-cells were transfected with small interference RNAs (siRNAs) targeting MDA5 or PTPN2 and subsequently exposed to intracellular synthetic dsRNA (polyinosinic-polycitidilic acid-PIC). Real-time RT-PCR, western blot and viability assays were performed to characterize gene/protein expression and viability. PIC increased MDA5 and PTPN2 mRNA expression, which was inhibited by the specific siRNAs. PIC triggered apoptosis in INS-1E and primary beta-cells and this was augmented by PTPN2 knockdown (KD), although inhibition of MDA5 did not modify PIC-induced apoptosis. In contrast, MDA5 silencing decreased PIC-induced cytokine and chemokine expression, although inhibition of PTPN2 induced minor or no changes in these inflammatory mediators. These findings indicate that changes in MDA5 and PTPN2 expression modify beta-cell responses to dsRNA. MDA5 regulates inflammatory signals, whereas PTPN2 may function as a defence mechanism against pro-apoptotic signals generated by dsRNA. These two candidate genes for T1D may thus modulate beta-cell apoptosis and/or local release of inflammatory mediators in the course of a viral infection by acting, at least in part, at the pancreatic beta-cell level.


Assuntos
RNA Helicases DEAD-box/metabolismo , Diabetes Mellitus Tipo 1/enzimologia , Diabetes Mellitus Tipo 1/genética , Células Secretoras de Insulina/patologia , Proteína Tirosina Fosfatase não Receptora Tipo 2/metabolismo , RNA de Cadeia Dupla/farmacologia , Vírus/metabolismo , Animais , Apoptose/efeitos dos fármacos , Quimiocinas/metabolismo , Ativação Enzimática/efeitos dos fármacos , Células Secretoras de Insulina/enzimologia , Interferon beta/genética , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Masculino , NF-kappa B/metabolismo , Poli I-C/farmacologia , Regiões Promotoras Genéticas/genética , RNA Interferente Pequeno/metabolismo , Ratos , Ratos Wistar
14.
Nutrients ; 14(18)2022 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-36145242

RESUMO

The loss of functional pancreatic ß-cell mass is an important hallmark of both type 1 and type 2 diabetes. The RNA-binding protein NOVA1 is expressed in human and rodent pancreatic ß-cells. Previous in vitro studies indicated that NOVA1 is necessary for glucose-stimulated insulin secretion and its deficiency-enhanced cytokine-induced apoptosis. Moreover, Bim, a proapoptotic protein, is differentially spliced and potentiates apoptosis in NOVA1-deficient ß-cells in culture. We generated two novel mouse models by Cre-Lox technology lacking Nova1 (ßNova1-/-) or Bim (ßBim-/-) in ß-cells. To test the impact of Nova1 or Bim deletion on ß-cell function, mice were subjected to multiple low-dose streptozotocin (MLD-STZ)-induced diabetes or high-fat diet-induced insulin resistance. ß-cell-specific Nova1 or Bim deficiency failed to affect diabetes development in response to MLD-STZ-induced ß-cell dysfunction and death evidenced by unaltered blood glucose levels and pancreatic insulin content. In addition, body composition, glucose and insulin tolerance test, and pancreatic insulin content were indistinguishable between control and ßNova1-/- or ßBim-/- mice on a high fat diet. Thus, Nova1 or Bim deletion in ß-cells does not impact on glucose homeostasis or diabetes development in mice. Together, these data argue against an in vivo role for the Nova1-Bim axis in ß-cells.


Assuntos
Proteína 11 Semelhante a Bcl-2/metabolismo , Diabetes Mellitus Experimental , Diabetes Mellitus Tipo 2 , Células Secretoras de Insulina , Animais , Glicemia/metabolismo , Citocinas/metabolismo , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Dieta Hiperlipídica , Glucose/metabolismo , Humanos , Insulina , Células Secretoras de Insulina/metabolismo , Camundongos , Antígeno Neuro-Oncológico Ventral , Obesidade/etiologia , Obesidade/metabolismo , Proteínas de Ligação a RNA/metabolismo , Estreptozocina
15.
Diabetes ; 71(4): 653-668, 2022 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-35044456

RESUMO

Type 1 diabetes (T1D) results from autoimmune destruction of ß-cells in the pancreas. Protein tyrosine phosphatases (PTPs) are candidate genes for T1D and play a key role in autoimmune disease development and ß-cell dysfunction. Here, we assessed the global protein and individual PTP profiles in the pancreas from nonobese mice with early-onset diabetes (NOD) mice treated with an anti-CD3 monoclonal antibody and interleukin-1 receptor antagonist. The treatment reversed hyperglycemia, and we observed enhanced expression of PTPN2, a PTP family member and T1D candidate gene, and endoplasmic reticulum (ER) chaperones in the pancreatic islets. To address the functional role of PTPN2 in ß-cells, we generated PTPN2-deficient human stem cell-derived ß-like and EndoC-ßH1 cells. Mechanistically, we demonstrated that PTPN2 inactivation in ß-cells exacerbates type I and type II interferon signaling networks and the potential progression toward autoimmunity. Moreover, we established the capacity of PTPN2 to positively modulate the Ca2+-dependent unfolded protein response and ER stress outcome in ß-cells. Adenovirus-induced overexpression of PTPN2 partially protected from ER stress-induced ß-cell death. Our results postulate PTPN2 as a key protective factor in ß-cells during inflammation and ER stress in autoimmune diabetes.


Assuntos
Diabetes Mellitus Tipo 1 , Células Secretoras de Insulina , Proteína Tirosina Fosfatase não Receptora Tipo 2/metabolismo , Animais , Apoptose/genética , Diabetes Mellitus Tipo 1/metabolismo , Estresse do Retículo Endoplasmático/fisiologia , Humanos , Células Secretoras de Insulina/metabolismo , Interferon gama/farmacologia , Camundongos , Camundongos Endogâmicos NOD , Proteína Tirosina Fosfatase não Receptora Tipo 2/genética
16.
Microbiome ; 10(1): 9, 2022 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-35045871

RESUMO

BACKGROUND: Short-chain fatty acids (SCFAs) produced by the gut microbiota have beneficial anti-inflammatory and gut homeostasis effects and prevent type 1 diabetes (T1D) in mice. Reduced SCFA production indicates a loss of beneficial bacteria, commonly associated with chronic autoimmune and inflammatory diseases, including T1D and type 2 diabetes. Here, we addressed whether a metabolite-based dietary supplement has an impact on humans with T1D. We conducted a single-arm pilot-and-feasibility trial with high-amylose maize-resistant starch modified with acetate and butyrate (HAMSAB) to assess safety, while monitoring changes in the gut microbiota in alignment with modulation of the immune system status. RESULTS: HAMSAB supplement was administered for 6 weeks with follow-up at 12 weeks in adults with long-standing T1D. Increased concentrations of SCFA acetate, propionate, and butyrate in stools and plasma were in concert with a shift in the composition and function of the gut microbiota. While glucose control and insulin requirements did not change, subjects with the highest SCFA concentrations exhibited the best glycemic control. Bifidobacterium longum, Bifidobacterium adolescentis, and vitamin B7 production correlated with lower HbA1c and basal insulin requirements. Circulating B and T cells developed a more regulatory phenotype post-intervention. CONCLUSION: Changes in gut microbiota composition, function, and immune profile following 6 weeks of HAMSAB supplementation were associated with increased SCFAs in stools and plasma. The persistence of these effects suggests that targeting dietary SCFAs may be a mechanism to alter immune profiles, promote immune tolerance, and improve glycemic control for the treatment of T1D. TRIAL REGISTRATION: ACTRN12618001391268. Registered 20 August 2018, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=375792 Video Abstract.


Assuntos
Diabetes Mellitus Tipo 1 , Diabetes Mellitus Tipo 2 , Microbioma Gastrointestinal , Microbiota , Animais , Diabetes Mellitus Tipo 2/microbiologia , Suplementos Nutricionais , Ácidos Graxos Voláteis , Humanos , Camundongos
17.
J Biol Chem ; 285(26): 19910-20, 2010 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-20421300

RESUMO

Type 1 diabetes is an autoimmune disorder characterized by chronic inflammation and pancreatic beta-cell loss. Here, we demonstrate that the proinflammatory cytokine interleukin-1beta, combined with interferon-gamma, induces the expression of the Bcl-2 homology 3 (BH3)-only activator PUMA (p53 up-regulated modulator of apoptosis) in beta-cells. Transcriptional activation of PUMA is regulated by nuclear factor-kappaB and endoplasmic reticulum stress but is independent of p53. PUMA activation leads to mitochondrial Bax translocation, cytochrome c release, and caspase-3 cleavage resulting in beta-cell demise. The antiapoptotic Bcl-XL protein is localized mainly at the mitochondria of the beta-cells and antagonizes PUMA action, but Bcl-XL is inactivated by the BH3-only sensitizer DP5/Hrk in cytokine-exposed beta-cells. Moreover, a pharmacological mimic of the BH3-only sensitizer Bad, which inhibits Bcl-XL and Bcl-2, induces PUMA-dependent beta-cell death and potentiates cytokine-induced apoptosis. Our data support a hierarchical activation of BH3-only proteins controlling the intrinsic pathway of beta-cell apoptosis in the context of inflammation and type 1 diabetes.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Apoptose/efeitos dos fármacos , Citocinas/farmacologia , Retículo Endoplasmático/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Animais , Proteínas Reguladoras de Apoptose/genética , Sítios de Ligação/genética , Compostos de Bifenilo/farmacologia , Western Blotting , Linhagem Celular Tumoral , Células Cultivadas , Expressão Gênica/efeitos dos fármacos , Humanos , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/metabolismo , Interferon gama/farmacologia , Interleucina-1beta/farmacologia , Mutação , NF-kappa B/metabolismo , Nitrofenóis/farmacologia , Piperazinas/farmacologia , Proteínas Proto-Oncogênicas/genética , Interferência de RNA , Ratos , Ratos Wistar , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sulfonamidas/farmacologia , Proteína bcl-X/genética , Proteína bcl-X/metabolismo
18.
Oncogene ; 40(33): 5155-5167, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34290399

RESUMO

Obesity affects more than 650 million individuals worldwide and is a well-established risk factor for the development of hepatocellular carcinoma (HCC). Oxidative stress can be considered as a bona fide tumor promoter, contributing to the initiation and progression of liver cancer. Indeed, one of the key events involved in HCC progression is excessive levels of reactive oxygen species (ROS) resulting from the fatty acid influx and chronic inflammation. This review provides insights into the different intracellular sources of obesity-induced ROS and molecular mechanisms responsible for hepatic tumorigenesis. In addition, we highlight recent findings pointing to the role of the dysregulated activity of BCL-2 proteins and protein tyrosine phosphatases (PTPs) in the generation of hepatic oxidative stress and ROS-mediated dysfunctional signaling, respectively. Finally, we discuss the potential and challenges of novel nanotechnology strategies to prevent ROS formation in obesity-associated HCC.


Assuntos
Carcinoma Hepatocelular , Humanos , Neoplasias Hepáticas , Estresse Oxidativo , Transdução de Sinais
19.
Diabetes ; 70(9): 2026-2041, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34183374

RESUMO

Most obese and insulin-resistant individuals do not develop diabetes. This is the result of the capacity of ß-cells to adapt and produce enough insulin to cover the needs of the organism. The underlying mechanism of ß-cell adaptation in obesity, however, remains unclear. Previous studies have suggested a role for STAT3 in mediating ß-cell development and human glucose homeostasis, but little is known about STAT3 in ß-cells in obesity. We observed enhanced cytoplasmic expression of STAT3 in severely obese subjects with diabetes. To address the functional role of STAT3 in adult ß-cells, we generated mice with tamoxifen-inducible partial or full deletion of STAT3 in ß-cells and fed them a high-fat diet before analysis. Interestingly, ß-cell heterozygous and homozygous STAT3-deficient mice showed glucose intolerance when fed a high-fat diet. Gene expression analysis with RNA sequencing showed that reduced expression of mitochondrial genes in STAT3 knocked down human EndoC-ß1H cells, confirmed in FACS-purified ß-cells from obese STAT3-deficient mice. Moreover, silencing of STAT3 impaired mitochondria activity in EndoC-ß1H cells and human islets, suggesting a mechanism for STAT3-modulated ß-cell function. Our study postulates STAT3 as a novel regulator of ß-cell function in obesity.


Assuntos
Intolerância à Glucose/metabolismo , Células Secretoras de Insulina/metabolismo , Mitocôndrias/metabolismo , Obesidade/metabolismo , Fator de Transcrição STAT3/metabolismo , Animais , Glicemia/metabolismo , Dieta Hiperlipídica , Genes Mitocondriais , Intolerância à Glucose/genética , Humanos , Insulina/metabolismo , Camundongos , Camundongos Knockout , Mitocôndrias/genética , Obesidade/genética , Fator de Transcrição STAT3/genética
20.
Trends Endocrinol Metab ; 31(12): 905-917, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33160815

RESUMO

A common feature in the pathophysiology of different types of diabetes is the reduction of ß cell mass and/or impairment of ß cell function. Diagnosis and treatment of type 1 and type 2 diabetes is currently hampered by a lack of reliable techniques to restore ß cell survival, to improve insulin secretion, and to quantify ß cell mass in patients. Current new approaches may allow us to precisely and specifically visualize ß cells in vivo and provide viable therapeutic strategies to preserve, recover, and regenerate ß cells. In this review, we discuss recent protective approaches for ß cells and the advantages and limitations of current imaging probes in the field.


Assuntos
Diabetes Mellitus Tipo 1/fisiopatologia , Diabetes Mellitus Tipo 2/fisiopatologia , Animais , Humanos , Células Secretoras de Insulina/fisiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA