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1.
Cell ; 150(6): 1223-34, 2012 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-22980982

RESUMO

Diabetes is associated with ß cell failure. But it remains unclear whether the latter results from reduced ß cell number or function. FoxO1 integrates ß cell proliferation with adaptive ß cell function. We interrogated the contribution of these two processes to ß cell dysfunction, using mice lacking FoxO1 in ß cells. FoxO1 ablation caused hyperglycemia with reduced ß cell mass following physiologic stress, such as multiparity and aging. Surprisingly, lineage-tracing experiments demonstrated that loss of ß cell mass was due to ß cell dedifferentiation, not death. Dedifferentiated ß cells reverted to progenitor-like cells expressing Neurogenin3, Oct4, Nanog, and L-Myc. A subset of FoxO1-deficient ß cells adopted the α cell fate, resulting in hyperglucagonemia. Strikingly, we identify the same sequence of events as a feature of different models of murine diabetes. We propose that dedifferentiation trumps endocrine cell death in the natural history of ß cell failure and suggest that treatment of ß cell dysfunction should restore differentiation, rather than promoting ß cell replication.


Assuntos
Desdiferenciação Celular , Diabetes Mellitus Tipo 2/patologia , Células Secretoras de Insulina/patologia , Animais , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/fisiopatologia , Proteína Forkhead Box O1 , Fatores de Transcrição Forkhead/metabolismo , Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Masculino , Camundongos , Pâncreas/patologia
2.
Bioorg Med Chem Lett ; 30(5): 126857, 2020 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-31982234

RESUMO

The discovery and optimization of a novel series of GPR142 agonists are described. These led to the identification of compound 21 (LY3325656), which demonstrated anti-diabetic benefits in pre-clinical studies and ADME/PK properties suitable for human dosing. Compound 21 is the first GPR142 agonist molecule advancing to phase 1 clinic trials for the treatment of Type 2 diabetes.


Assuntos
Benzamidas/uso terapêutico , Diabetes Mellitus Experimental/tratamento farmacológico , Hipoglicemiantes/uso terapêutico , Receptores Acoplados a Proteínas G/agonistas , Triazóis/uso terapêutico , Animais , Benzamidas/síntese química , Benzamidas/farmacocinética , Cães , Descoberta de Drogas , Avaliação Pré-Clínica de Medicamentos , Técnicas de Inativação de Genes , Humanos , Hipoglicemiantes/síntese química , Hipoglicemiantes/farmacocinética , Camundongos Knockout , Estrutura Molecular , Ratos , Receptores Acoplados a Proteínas G/genética , Relação Estrutura-Atividade , Triazóis/síntese química , Triazóis/farmacocinética
3.
J Diabetes Investig ; 15(7): 797-804, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38426644

RESUMO

Insulin-deficient (type 1) diabetes is treated by providing insulin to maintain euglycemia. The current standard of care is a quasi-closed loop integrating automated insulin delivery with a continuous glucose monitoring sensor. Cell replacement technologies are advancing as an alternative treatment and have been tested as surrogates to cadaveric islets in transplants. In addition, immunomodulatory treatments to delay the onset of type 1 diabetes in high-risk (stage 2) individuals have gained regulatory approval. We have pioneered a cell conversion approach to restore insulin production through pharmacological conversion of intestinal epithelial cells into insulin-producing cells. We have advanced this approach along a translational trajectory through the discovery of small molecule forkhead box protein O1 inhibitors. When administered to different rodent models of insulin-deficient diabetes, these inhibitors have resulted in robust glucose-lowering responses and generation of insulin-producing cells in the gut epithelium. We review past work and delineate a path to human clinical trials.


Assuntos
Diabetes Mellitus Tipo 1 , Células Epiteliais , Células Secretoras de Insulina , Humanos , Animais , Diabetes Mellitus Tipo 1/terapia , Células Epiteliais/metabolismo , Células Secretoras de Insulina/metabolismo , Insulina/metabolismo , Mucosa Intestinal/metabolismo
4.
J Biol Chem ; 287(17): 13944-51, 2012 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-22389493

RESUMO

Complications of atherosclerosis are the leading cause of death of patients with type 2 (insulin-resistant) diabetes. Understanding the mechanisms by which insulin resistance and hyperglycemia contribute to atherogenesis in key target tissues (liver, vessel wall, hematopoietic cells) can assist in the design of therapeutic approaches. We have shown that hyperglycemia induces FoxO1 deacetylation and that targeted knock-in of alleles encoding constitutively deacetylated FoxO1 in mice (Foxo1(KR/KR)) improves hepatic lipid metabolism and decreases macrophage inflammation, setting the stage for a potential anti-atherogenic effect of this mutation. Surprisingly, we report here that when Foxo1(KR/KR) mice are intercrossed with low density lipoprotein receptor knock-out mice (Ldlr(-/-)), they develop larger aortic root atherosclerotic lesions than Ldlr(-/-) controls despite lower plasma cholesterol and triglyceride levels. The phenotype is unaffected by transplanting bone marrow from Ldlr(-/-) mice into Foxo1(KR/KR) mice, indicating that it is independent of hematopoietic cells and suggesting that the primary lesion in Foxo1(KR/KR) mice occurs in the vessel wall. Experiments in isolated endothelial cells from Foxo1(KR/KR) mice indicate that deacetylation favors FoxO1 nuclear accumulation and exerts target gene-specific effects, resulting in higher Icam1 and Tnfα expression and increased monocyte adhesion. The data indicate that FoxO1 deacetylation can promote vascular endothelial changes conducive to atherosclerotic plaque formation.


Assuntos
Aterosclerose/metabolismo , Diabetes Mellitus/metabolismo , Endotélio Vascular/patologia , Fatores de Transcrição Forkhead/metabolismo , Acetilação , Alelos , Animais , Apoptose , Transplante de Medula Óssea , Células Endoteliais/citologia , Proteína Forkhead Box O1 , Humanos , Hiperglicemia/metabolismo , Inflamação , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Estresse Oxidativo , Transdução de Sinais
5.
J Biol Chem ; 286(11): 9797-804, 2011 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-21239487

RESUMO

Type 2 diabetes results from an impairment of insulin action. The first demonstrable abnormality of insulin signaling is a decrease of insulin-dependent glucose disposal followed by an increase in hepatic glucose production. In an attempt to dissect the relative importance of these two changes in disease progression, we have employed genetic knock-outs/knock-ins of the insulin receptor. Previously, we demonstrated that insulin receptor knock-out mice (Insr(-/-)) could be rescued from diabetes by reconstitution of insulin signaling in liver, brain, and pancreatic ß cells (L1 mice). In this study, we used a similar approach to reconstitute insulin signaling in tissues that display insulin-dependent glucose uptake. Using GLUT4-Cre mice, we restored InsR expression in muscle, fat, and brain of Insr(-/-) mice (GIRKI (Glut4-insulin receptor knock-in line 1) mice). Unlike L1 mice, GIRKI mice failed to thrive and developed diabetes, although their survival was modestly extended when compared with Insr(-/-). The data underscore the role of developmental factors in the presentation of murine diabetes. The broader implication of our findings is that diabetes treatment should not necessarily target the same tissues that are responsible for disease pathogenesis.


Assuntos
Tecido Adiposo Branco/metabolismo , Encéfalo/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Insulina/metabolismo , Músculo Esquelético/metabolismo , Transdução de Sinais , Tecido Adiposo Branco/patologia , Animais , Encéfalo/patologia , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/patologia , Diabetes Mellitus Tipo 2/terapia , Transportador de Glucose Tipo 4/genética , Transportador de Glucose Tipo 4/metabolismo , Insulina/genética , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patologia , Camundongos , Camundongos Knockout , Músculo Esquelético/patologia , Receptor de Insulina/genética , Receptor de Insulina/metabolismo
6.
Mol Metab ; 66: 101624, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36341906

RESUMO

OBJECTIVE: Lifelong insulin replacement remains the mainstay of type 1 diabetes treatment. Genetic FoxO1 ablation promotes enteroendocrine cell (EECs) conversion into glucose-responsive ß-like cells. Here, we tested whether chemical FoxO1 inhibitors can generate ß-like gut cells. METHODS: We used Ngn3-or Villin-driven FoxO1 ablation to capture the distinctive developmental effects of FoxO1 on EEC pool. We combined FoxO1 ablation with Notch inhibition to enhance the expansion of EEC pool. We tested the ability of an orally available small molecule of FoxO1 inhibitor, Cpd10, to phenocopy genetic ablation of FoxO1. We evaluated the therapeutic impact of genetic ablation or chemical inhibition of FoxO1 on insulin-deficient diabetes in Ins2Akita/+ mice. RESULTS: Pan-intestinal epithelial FoxO1 ablation expanded the EEC pool, induced ß-like cells, and improved glucose tolerance in Ins2Akita/+ mice. This genetic effect was phenocopied by Cpd10. Cpd10 induced ß-like cells that released insulin in response to glucose in gut organoids, and this effect was enhanced by the Notch inhibitor, DBZ. In Ins2Akita/+ mice, a five-day course of either Cpd10 or DBZ induced intestinal insulin-immunoreactive ß-like cells, lowered glycemia, and increased plasma insulin levels without apparent adverse effects. CONCLUSION: These results provide proof of principle of gut cell conversion into ß-like cells by a small molecule FoxO1 inhibitor, paving the way for clinical applications.


Assuntos
Diabetes Mellitus , Células Secretoras de Insulina , Animais , Camundongos , Células Enteroendócrinas , Proteína Forkhead Box O1/genética , Glucose/farmacologia , Insulina/genética , Organoides , Receptores Notch/antagonistas & inibidores
7.
J Clin Invest ; 132(24)2022 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-36282572

RESUMO

Targeting lineage-defined transcriptional dependencies has emerged as an effective therapeutic strategy in cancer treatment. Through screening for molecular vulnerabilities of mantle cell lymphoma (MCL), we identified a set of transcription factors (TFs) including FOXO1, EBF1, PAX5, and IRF4 that are essential for MCL propagation. Integrated chromatin immunoprecipitation and sequencing (ChIP-Seq) with transcriptional network reconstruction analysis revealed FOXO1 as a master regulator that acts upstream in the regulatory TF hierarchy. FOXO1 is both necessary and sufficient to drive MCL lineage commitment through supporting the lineage-specific transcription programs. We further show that FOXO1, but not its close paralog FOXO3, can reprogram myeloid leukemia cells and induce B-lineage gene expression. Finally, we demonstrate that cpd10, a small molecule identified from an enriched FOXO1 inhibitor library, induces a robust cytotoxic response in MCL cells in vitro and suppresses MCL progression in vivo. Our findings establish FOXO1 inhibition as a therapeutic strategy targeting lineage-driven transcriptional addiction in MCL.


Assuntos
Linfoma de Célula do Manto , Humanos , Adulto , Linfoma de Célula do Manto/genética , Redes Reguladoras de Genes , Proteína Forkhead Box O1/genética
8.
Mol Metab ; 49: 101187, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33577983

RESUMO

OBJECTIVE: Forkhead box protein O1 (FOXO1) plays a key role in regulating hepatic glucose production, but investigations of FOXO1 inhibition as a potential therapeutic approach have been hampered by a lack of selective chemical inhibitors. By profiling structurally diverse FOXO1 inhibitors, the current study validates FOXO1 as a viable target for the treatment of diabetes. METHODS: Using reporter gene assays, hepatocyte gene expression studies, and in vivo studies in mice, we profiled our leading tool compound 10 and a previously characterized FOXO1 inhibitor, AS1842856 (AS). RESULTS: We show that AS has significant FOXO1-independent effects, as demonstrated by testing in FOXO1-deficient cell lines and animals, while compound 10 is highly selective for FOXO1 both in vitro and in vivo and fails to elicit any effect in genetic models of FOXO1 ablation. Chronic administration of compound 10 improved insulin sensitivity and glucose control in db/db mice without causing weight gain. Furthermore, chronic compound 10 treatment combined with FGF21 led to synergistic glucose lowering in lean, streptozotocin-induced diabetic mice. CONCLUSIONS: We show that the widely used AS compound has substantial off-target activities and that compound 10 is a superior tool molecule for the investigation of FOXO1 function. In addition, we provide preclinical evidence that selective FOXO1 inhibition has potential therapeutic benefits for diabetes as a monotherapy or in combination with FGF21.


Assuntos
Glicemia/metabolismo , Fatores de Crescimento de Fibroblastos/metabolismo , Proteína Forkhead Box O1/metabolismo , Animais , Diabetes Mellitus Tipo 2/metabolismo , Fatores de Crescimento de Fibroblastos/genética , Proteína Forkhead Box O1/efeitos dos fármacos , Proteína Forkhead Box O1/genética , Glucose/metabolismo , Hepatócitos/metabolismo , Resistência à Insulina , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos ICR , Camundongos Knockout , Quinolonas/farmacologia
9.
Dev Biol ; 314(1): 100-11, 2008 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-18174108

RESUMO

Wingless (Wg)/Wnt signaling directs a variety of cellular processes during animal development by promoting the association of Armadillo/beta-catenin with TCFs on Wg-regulated enhancers (WREs). Split ends (Spen), a nuclear protein containing RNA recognition motifs (RRMs) and a SPOC domain, is required for optimal Wg signaling in several fly tissues. In this report, we demonstrate that Spenito (Nito), the only other fly protein containing RRMs and a SPOC domain, acts together with Spen to positively regulate Wg signaling. The partial defect in Wg signaling observed with spen RNAi was enhanced by simultaneous knockdown of nito while it was rescued by expression of nito in wing imaginal discs. In cell culture, depletion of both factors causes a greater defect in the activation of several Wg targets than RNAi of either spen or nito alone. These nuclear proteins are not required for Armadillo stabilization or the recruitment of TCF and Armadillo to a WRE. Loss of Wg target gene activation in cells depleted for spen and nito was not dependent on the transcriptional repressor Yan or Suppressor of Hairless, two previously identified targets of Spen. We propose that Spen and Nito act redundantly downstream of TCF/Armadillo to activate many Wg transcriptional targets.


Assuntos
Proteínas de Drosophila/fisiologia , Drosophila/metabolismo , Proteínas de Homeodomínio/fisiologia , Proteínas Nucleares/fisiologia , Proteínas Proto-Oncogênicas/fisiologia , Animais , Animais Geneticamente Modificados , Proteínas do Domínio Armadillo/metabolismo , Células Cultivadas , Drosophila/genética , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Proteínas do Olho/metabolismo , Proteínas de Ligação a RNA , Proteínas Repressoras/metabolismo , Transdução de Sinais , Fatores de Transcrição/metabolismo , Ativação Transcricional , Asas de Animais/fisiologia , Proteína Wnt1
10.
J Clin Invest ; 116(3): 775-82, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16485043

RESUMO

Diabetes is associated with defective beta cell function and altered beta cell mass. The mechanisms regulating beta cell mass and its adaptation to insulin resistance are unknown. It is unclear whether compensatory beta cell hyperplasia is achieved via proliferation of existing beta cells or neogenesis from progenitor cells embedded in duct epithelia. We have used transgenic mice expressing a mutant form of the forkhead-O1 transcription factor (FoxO1) in both pancreatic ductal and endocrine beta cells to assess the contribution of these 2 compartments to islet expansion. We show that the mutant FoxO1 transgene prevents beta cell replication in 2 models of beta cell hyperplasia, 1 due to peripheral insulin resistance (Insulin receptor transgenic knockouts) and 1 due to ectopic local expression of IGF2 (Elastase-IGF2 transgenics), without affecting insulin secretion. In contrast, we failed to detect a specific effect of the FoxO1 transgene on the number of periductal beta cells. We propose that beta cell compensation to insulin resistance is a proliferative response of existing beta cells to growth factor signaling and requires FoxO1 nuclear exclusion.


Assuntos
Fatores de Transcrição Forkhead/fisiologia , Resistência à Insulina/fisiologia , Células Secretoras de Insulina/metabolismo , Animais , Diabetes Mellitus/genética , Modelos Animais de Doenças , Proteína Forkhead Box O1 , Fatores de Transcrição Forkhead/genética , Fator de Crescimento Insulin-Like II/genética , Fator de Crescimento Insulin-Like II/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Receptor de Insulina/deficiência , Receptor de Insulina/genética
11.
Cancer Res ; 67(2): 482-91, 2007 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-17234755

RESUMO

Wnt ligands have pleiotropic and context-specific roles in embryogenesis and adult tissues. Among other effects, certain Wnts stabilize the beta-catenin protein, leading to the ability of beta-catenin to activate T-cell factor (TCF)-mediated transcription. Mutations resulting in constitutive beta-catenin stabilization underlie development of several human cancers. Genetic studies in Drosophila highlighted the split ends (spen) gene as a positive regulator of Wnt-dependent signaling. We have assessed the role of SHARP, a human homologue of spen, in Wnt/beta-catenin/TCF function in mammalian cells. We found that SHARP gene and protein expression is elevated in human colon and ovarian endometrioid adenocarcinomas and mouse colon adenomas and carcinomas carrying gene defects leading to beta-catenin dysregulation. When ectopically expressed, the silencing mediator for retinoid and thyroid receptors/histone deacetylase 1-associated repressor protein (SHARP) protein potently enhanced beta-catenin/TCF transcription of a model reporter gene and cellular target genes. Inhibition of endogenous SHARP function via RNA inhibitory (RNAi) approaches antagonized beta-catenin/TCF-mediated activation of target genes. The effect of SHARP on beta-catenin/TCF-regulated genes was mediated via a functional interaction between SHARP and TCF. beta-Catenin-dependent neoplastic transformation of RK3E cells was enhanced by ectopic expression of SHARP, and RNAi-mediated inhibition of endogenous SHARP in colon cancer cells inhibited their transformed growth. In toto, our findings implicate SHARP as an important positive regulator of Wnt signaling in cancers with beta-catenin dysregulation.


Assuntos
Transformação Celular Neoplásica/metabolismo , Neoplasias do Colo/metabolismo , Proteínas de Homeodomínio/fisiologia , Proteínas Nucleares/fisiologia , Proteínas Wnt/metabolismo , beta Catenina/metabolismo , Adenoma/genética , Adenoma/metabolismo , Adenoma/patologia , Animais , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/patologia , Neoplasias do Colo/genética , Neoplasias do Colo/patologia , Proteínas de Ligação a DNA , Células HCT116 , Proteínas de Homeodomínio/biossíntese , Proteínas de Homeodomínio/genética , Humanos , Camundongos , Camundongos Transgênicos , Proteínas Nucleares/biossíntese , Proteínas Nucleares/genética , Proteínas de Ligação a RNA , Transdução de Sinais , Ativação Transcricional
12.
Mol Metab ; 11: 205-211, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29506910

RESUMO

OBJECTIVE: GPR142 agonists are being pursued as novel diabetes therapies by virtue of their insulin secretagogue effects. But it is undetermined whether GPR142's functions in pancreatic islets are limited to regulating insulin secretion. The current study expands research on its action. METHODS AND RESULTS: We demonstrated by in situ hybridization and immunostaining that GPR142 is expressed not only in ß cells but also in a subset of α cells. Stimulation of GPR142 by a selective agonist increased glucagon secretion in both human and mouse islets. More importantly, the GPR142 agonist also potentiated glucagon-like peptide-1 (GLP-1) production and its release from islets through a mechanism that involves upregulation of prohormone convertase 1/3 expression. Strikingly, stimulation of insulin secretion and increase in insulin content via GPR142 engagement requires intact GLP-1 receptor signaling. Furthermore, GPR142 agonist increased ß cell proliferation and protected both mouse and human islets against stress-induced apoptosis. CONCLUSIONS: Collectively, we provide here evidence that local GLP-1 release from α cells defines GPR142's beneficial effects on improving ß cell function and mass, and we propose that GPR142 agonism may have translatable and durable efficacy for the treatment of type 2 diabetes.


Assuntos
Peptídeo 1 Semelhante ao Glucagon/metabolismo , Células Secretoras de Glucagon/metabolismo , Células Secretoras de Insulina/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Animais , Apoptose , Proliferação de Células , Células Cultivadas , Receptor do Peptídeo Semelhante ao Glucagon 1/metabolismo , Humanos , Secreção de Insulina , Células Secretoras de Insulina/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pró-Proteína Convertase 1/metabolismo
13.
Diabetes ; 66(11): 2789-2799, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28877911

RESUMO

Transcripts of key enzymes in the Leloir pathway of galactose metabolism in mouse livers are significantly increased after chronic high-fat/high-sucrose feeding. UDP-galactose-4-epimerase (GALE) is the last enzyme in this pathway that converts UDP-galactose to UDP-glucose and was previously identified as a downstream target of the endoplasmic reticulum (ER) stress effector spliced X-box binding protein 1, suggesting an interesting cross talk between galactose and glucose metabolism in the context of hepatic ER stress and whole-body metabolic fitness. However, its specific role in glucose metabolism is not established. Using an inducible and tissue-specific mouse model, we report that hepatic overexpression of Gale increases gluconeogenesis from pyruvate and impairs glucose tolerance. Conversely, genetic reduction of Gale in liver improves glucose tolerance. Transcriptional profiling identifies trefoil factor 3 (Tff3) as one of the downstream targets of GALE. Restoration of Tff3 expression corrects glucose intolerance in Gale-overexpressing mice. These studies reveal a new link between hepatic GALE activity and whole-body glucose homeostasis via regulation of hepatic Tff3 expression.


Assuntos
Glucose/metabolismo , Homeostase/fisiologia , Fígado/enzimologia , Fator Trefoil-3/metabolismo , UDPglucose 4-Epimerase/metabolismo , Animais , Retículo Endoplasmático/metabolismo , Regulação Enzimológica da Expressão Gênica/fisiologia , Camundongos , Camundongos Transgênicos , Fator Trefoil-3/genética , UDPglucose 4-Epimerase/genética
14.
Endocrinology ; 147(12): 5760-7, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16973725

RESUMO

Type I diabetes is characterized by little or no insulin production and hyperglycemic conditions. It is also associated with significant bone loss and increased bone marrow adiposity. To examine the role of reduced insulin signaling in type I diabetic bone loss without inducing hyperglycemia, we used genetically reconstituted insulin receptor knockout mice (IRKO-L1) that are euglycemic as a result of human insulin receptor transgene expression in the pancreas, liver, and brain. RT-PCR analyses demonstrated undetectable levels of insulin receptor expression in IRKO-L1 bone, yet IRKO-L1 bones exhibit similar (and trend toward greater) bone density compared with wild-type animals as determined by microcomputed tomography. More detailed bone analyses indicated that cortical bone area was increased in tibias of IRKO-L1 mice. Osteoblast markers (osteocalcin and runx2 mRNA levels) and resorption markers (serum pyridinoline levels) were similar in wild-type and IRKO-L1 bones. When marrow adiposity was examined, we noticed a decrease in adipocyte number and fatty-acid-binding protein 2 expression in IRKO-L1 mice compared with wild-type mice. Bone marrow stromal cell cultures obtained from wild-type and IRKO-L1 mice demonstrated similar adipogenic and osteogenic potentials, indicating that systemic factors likely contribute to differences in marrow adiposity in vivo. Interestingly, IGF-I receptor mRNA levels were elevated in IRKO-L1 bones, suggesting (in combination with hyperinsulinemic conditions) that increased IGF-I receptor signaling may represent a compensatory response and contribute to the changes in cortical bone. Taken together, these results suggest that reduced insulin receptor signaling in bone is not a major factor contributing to bone loss in type I diabetes.


Assuntos
Densidade Óssea/fisiologia , Osso e Ossos/metabolismo , Receptor de Insulina/genética , Receptor de Insulina/metabolismo , Adipócitos Brancos/citologia , Animais , Medula Óssea/metabolismo , Proteínas de Ligação a Ácido Graxo/metabolismo , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Osteocalcina/metabolismo , Receptor IGF Tipo 1/metabolismo
15.
PLoS One ; 11(4): e0154452, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27104960

RESUMO

GPR142 is an islet-enriched G protein-coupled receptor that has been investigated as a novel therapeutic target for the treatment of type 2 diabetes by virtue of its insulin secretagogue activity. However, the signaling pathways downstream of GPR142 and whether its stimulation of insulin release is glucose-dependent remain poorly characterized. In this study, we show that both native and synthetic GPR142 agonists can activate Gq as well as Gi signaling when GPR142 is recombinantly expressed in HEK293 cells. However, in primary pancreatic islets, a native cellular system, the insulin secretagogue activity of GPR142 agonists only requires Gq activation. In addition, our results show that stimulation of insulin secretion by GPR142 in pancreatic islets is strictly glucose-dependent.


Assuntos
Aminopiridinas/farmacologia , Glucose/farmacologia , Insulina/agonistas , Subunidades Proteicas/agonistas , Pirazóis/farmacologia , Receptores Acoplados a Proteínas G/agonistas , Triptofano/farmacologia , Animais , Colforsina/farmacologia , AMP Cíclico/metabolismo , Regulação da Expressão Gênica , Glucose/metabolismo , Células HEK293 , Humanos , Insulina/metabolismo , Secreção de Insulina , Ilhotas Pancreáticas/citologia , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Proteína Quinase 1 Ativada por Mitógeno/genética , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/genética , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Fosforilação , Cultura Primária de Células , Subunidades Proteicas/genética , Subunidades Proteicas/metabolismo , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética
16.
PLoS One ; 11(6): e0157298, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27322810

RESUMO

GPR142, a putative amino acid receptor, is expressed in pancreatic islets and the gastrointestinal tract, but the ligand affinity and physiological role of this receptor remain obscure. In this study, we show that in addition to L-Tryptophan, GPR142 signaling is also activated by L-Phenylalanine but not by other naturally occurring amino acids. Furthermore, we show that Tryptophan and a synthetic GPR142 agonist increase insulin and incretin hormones and improve glucose disposal in mice in a GPR142-dependent manner. In contrast, Phenylalanine improves in vivo glucose disposal independently of GPR142. Noteworthy, refeeding-induced elevations in insulin and glucose-dependent insulinotropic polypeptide are blunted in Gpr142 null mice. In conclusion, these findings demonstrate GPR142 is a Tryptophan receptor critically required for insulin and incretin hormone regulation and suggest GPR142 agonists may be effective therapies that leverage amino acid sensing pathways for the treatment of type 2 diabetes.


Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Glucose/metabolismo , Fenilalanina/metabolismo , Receptores Acoplados a Proteínas G/genética , Triptofano/metabolismo , Animais , Glicemia , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/patologia , Glucose/genética , Humanos , Incretinas/genética , Incretinas/metabolismo , Insulina/genética , Insulina/metabolismo , Secreção de Insulina , Células Secretoras de Insulina , Ilhotas Pancreáticas/metabolismo , Camundongos , Camundongos Knockout , Fenilalanina/administração & dosagem , Receptores Acoplados a Proteínas G/agonistas , Receptores Acoplados a Proteínas G/efeitos dos fármacos , Triptofano/administração & dosagem
17.
Cell Metab ; 24(3): 420-433, 2016 09 13.
Artigo em Inglês | MEDLINE | ID: mdl-27626200

RESUMO

"Beige" adipocytes reside in white adipose tissue (WAT) and dissipate energy as heat. Several studies have shown that cold temperature can activate pro-opiomelanocortin-expressing (POMC) neurons and increase sympathetic neuronal tone to regulate WAT beiging. WAT, however, is traditionally known to be sparsely innervated. Details regarding the neuronal innervation and, more importantly, the propagation of the signal within the population of "beige" adipocytes are sparse. Here, we demonstrate that beige adipocytes display an increased cell-to-cell coupling via connexin 43 (Cx43) gap junction channels. Blocking of Cx43 channels by 18α-glycyrrhetinic acid decreases POMC-activation-induced adipose tissue beiging. Adipocyte-specific deletion of Cx43 reduces WAT beiging to a level similar to that observed in denervated fat pads. In contrast, overexpression of Cx43 is sufficient to promote beiging even with mild cold stimuli. These data reveal the importance of cell-to-cell communication, effective in cold-induced WAT beiging, for the propagation of limited neuronal inputs in adipose tissue.


Assuntos
Tecido Adiposo Bege/metabolismo , Tecido Adiposo Branco/metabolismo , Conexina 43/metabolismo , Neurônios/metabolismo , Transdução de Sinais , Adaptação Fisiológica/efeitos dos fármacos , Tecido Adiposo Bege/efeitos dos fármacos , Tecido Adiposo Marrom/efeitos dos fármacos , Tecido Adiposo Marrom/metabolismo , Tecido Adiposo Branco/efeitos dos fármacos , Tecido Adiposo Branco/inervação , Animais , Temperatura Baixa , Denervação , Junções Comunicantes/efeitos dos fármacos , Junções Comunicantes/metabolismo , Deleção de Genes , Ácido Glicirretínico/análogos & derivados , Ácido Glicirretínico/farmacologia , Camundongos Endogâmicos C57BL , Modelos Biológicos , Neurônios/efeitos dos fármacos , Regiões Promotoras Genéticas/genética , Transdução de Sinais/efeitos dos fármacos , Sistema Nervoso Simpático/efeitos dos fármacos , Sistema Nervoso Simpático/patologia , Proteína Desacopladora 1/genética , Proteína Desacopladora 1/metabolismo
18.
PLoS One ; 9(2): e88908, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24558447

RESUMO

Inhibition of Diacylglycerol O-acyltransferase 1 (DGAT1) has been a mechanism of interest for metabolic disorders. DGAT1 inhibition has been shown to be a key regulator in an array of metabolic pathways; however, based on the DGAT1 KO mouse phenotype the anticipation is that pharmacological inhibition of DGAT1 could potentially lead to skin related adverse effects. One of the aims in developing small molecule DGAT1 inhibitors that target key metabolic tissues is to avoid activity on skin-localized DGAT1 enzyme. In this report we describe a modeling-based approach to identify molecules with physical properties leading to differential exposure distribution. In addition, we demonstrate histological and RNA based biomarker approaches that can detect sebaceous gland atrophy pre-clinically that could be used as potential biomarkers in a clinical setting.


Assuntos
Diacilglicerol O-Aciltransferase/antagonistas & inibidores , Descoberta de Drogas , Inibidores Enzimáticos/efeitos adversos , Inibidores Enzimáticos/farmacologia , Glândulas Sebáceas/efeitos dos fármacos , Glândulas Sebáceas/patologia , Animais , Atrofia/induzido quimicamente , Atrofia/enzimologia , Biomarcadores/metabolismo , Inibidores Enzimáticos/química , Inibidores Enzimáticos/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Masculino , Camundongos , Pele/efeitos dos fármacos , Pele/enzimologia , Pele/metabolismo , Bibliotecas de Moléculas Pequenas/efeitos adversos , Bibliotecas de Moléculas Pequenas/química , Bibliotecas de Moléculas Pequenas/metabolismo , Bibliotecas de Moléculas Pequenas/farmacologia
19.
PLoS One ; 8(1): e54480, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23336002

RESUMO

Diacylglycerol acyltransferase-1 (DGAT1) is a potential therapeutic target for treatment of obesity and related metabolic diseases. However, the degree of DGAT1 inhibition required for metabolic benefits is unclear. Here we show that partial DGAT1 deficiency in mice suppressed postprandial triglyceridemia, led to elevations in glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) only following meals with very high lipid content, and did not protect from diet-induced obesity. Maximal DGAT1 inhibition led to enhanced GLP-1 and PYY secretion following meals with physiologically relevant lipid content. Finally, combination of DGAT1 inhibition with dipeptidyl-peptidase-4 (DPP-4) inhibition led to further enhancements in active GLP-1 in mice and dogs. The current study suggests that targeting DGAT1 to enhance postprandial gut hormone secretion requires maximal inhibition, and suggests combination with DPP-4i as a potential strategy to develop DGAT1 inhibitors for treatment of metabolic diseases.


Assuntos
Diacilglicerol O-Aciltransferase/genética , Hormônios Gastrointestinais/metabolismo , Trato Gastrointestinal/metabolismo , Período Pós-Prandial , Animais , Sequência de Bases , Diacilglicerol O-Aciltransferase/deficiência , Diacilglicerol O-Aciltransferase/metabolismo , Dieta , Dipeptidil Peptidase 4/genética , Dipeptidil Peptidase 4/metabolismo , Cães , Ativação Enzimática , Feminino , Esvaziamento Gástrico/genética , Dosagem de Genes , Regulação da Expressão Gênica , Ordem dos Genes , Genótipo , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Metabolismo dos Lipídeos , Masculino , Camundongos , Camundongos Knockout , Dados de Sequência Molecular , Triglicerídeos/sangue
20.
PLoS One ; 7(2): e31487, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22319636

RESUMO

Insulin receptor (InsR) signaling through transcription factor FoxO1 is important in the development of hypothalamic neuron feeding circuits, but knowledge about underlying mechanisms is limited. To investigate the role of InsR/FoxO1 signaling in the development and maintenance of these circuits, we surveyed the pool of hypothalamic neurons expressing Pomc mRNA in different mouse models of impaired hypothalamic InsR signaling. InsR ablation in the entire hypothalamus did not affect Pomc-neuron number at birth, but resulted in a 25% increase, most notably in the middle arcuate nucleus region, in young adults. Selective restoration of InsR expression in POMC neurons in these mice partly reversed the abnormality, resulting in a 10% decrease compared to age-matched controls. To establish whether FoxO1 signaling plays a role in this process, we examined POMC neuron number in mice with POMC-specific deletion of FoxO1, and detected a 23% decrease in age-matched animals, consistent with a cell-autonomous role of InsR/FoxO1 signaling in regulating POMC neuron number, distinct from its established role to activate Pomc transcription. These changes in Pomc cells occurred in the absence of marked changes in humoral factors or hypothalamic NPY neurons.


Assuntos
Fatores de Transcrição Forkhead/fisiologia , Hipotálamo/citologia , Neurônios/citologia , Pró-Opiomelanocortina/genética , Receptor de Insulina/fisiologia , Transdução de Sinais/fisiologia , Fatores Etários , Animais , Contagem de Células , Proteína Forkhead Box O1 , Camundongos , RNA Mensageiro/análise , Transcrição Gênica
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