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1.
Int J Mol Sci ; 22(16)2021 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-34445459

RESUMO

An understanding of the immune mechanisms that lead to rejection versus tolerance of allogeneic pancreatic islet grafts is of paramount importance, as it facilitates the development of innovative methods to improve the transplant outcome. Here, we used our established intraocular islet transplant model to gain novel insight into changes in the local metabolome and proteome within the islet allograft's immediate microenvironment in association with immune-mediated rejection or tolerance. We performed integrated metabolomics and proteomics analyses in aqueous humor samples representative of the graft's microenvironment under each transplant outcome. The results showed that several free amino acids, small primary amines, and soluble proteins related to the Warburg effect were upregulated or downregulated in association with either outcome. In general, the observed shifts in the local metabolite and protein profiles in association with rejection were consistent with established pro-inflammatory metabolic pathways and those observed in association with tolerance were immune regulatory. Taken together, the current findings further support the potential of metabolic reprogramming of immune cells towards immune regulation through targeted pharmacological and dietary interventions against specific metabolic pathways that promote the Warburg effect to prevent the rejection of transplanted islets and promote their immune tolerance.


Assuntos
Rejeição de Enxerto/metabolismo , Células Secretoras de Insulina/metabolismo , Transplante das Ilhotas Pancreáticas , Metabolômica , Proteômica , Tolerância ao Transplante , Aloenxertos , Animais , Rejeição de Enxerto/patologia , Células Secretoras de Insulina/patologia , Masculino , Camundongos
2.
Zhongguo Zhong Yao Za Zhi ; 46(14): 3643-3649, 2021 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-34402288

RESUMO

Type 2 diabetes mellitus( T2 DM) is a common chronic metabolic disease characterized by persistent hyperglycemia and insulin resistance. In pancreatic ß-cells,glucose-stimulated insulin secretion( GSIS) plays a pivotal role in maintaining the balance of blood glucose level. Previous studies have shown that geniposide,one of the active components of Gardenia jasminoides,could quickly regulate the absorption and metabolism of glucose,and affect glucose-stimulated insulin secretion in pancreatic ß cells,but the specific mechanism needs to be further explored. Emerging evidence indicated that glycosylation of glucose transporter( GLUT) has played a key role in sensing cell microenvironmental changes and regulating glucose homeostasis in eucaryotic cells. In this study,we studied the effects of geniposide on the key molecules of GLUT2 glycosylation in pancreatic ß cells. The results showed that geniposide could significantly up-regulate the mRNA and protein levels of Glc NAc T-Ⅳa glycosyltransferase( Gn T-Ⅳa) and galectin-9 but had no signi-ficant effect on the expression of clathrin,and geniposide could distinctively regulate the protein level of Gn T-Ⅳa in a short time( 1 h) under the conditions of low and medium glucose concentrations,but had no significant effect on the protein level of galectin-9. In addition,geniposide could also remarkably affect the protein level of glycosylated GLUT2 in a short-time treatment. The above results suggested that geniposide could quickly regulate the protein level of Gn T-Ⅳa,a key molecule of protein glycosylation in INS-1 rat pancreatic ßcells and affect the glycosylation of GLUT2. These findings suggested that the regulation of geniposide on glucose absorption,metabolism and glucose-stimulated insulin secretion might be associated with its efficacy in regulating GLUT2 glycosylation and affecting its distribution on the cell membrane and cytoplasm in pancreatic ß cells.


Assuntos
Diabetes Mellitus Tipo 2 , Células Secretoras de Insulina , Animais , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Glucose/metabolismo , Glicosilação , Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Iridoides , Ratos
3.
Methods Mol Biol ; 2351: 321-334, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34382198

RESUMO

Loss-of-function experiments are essential for the functional investigation of cis-regulatory elements (CREs), such as transcriptional enhancers. This can be achieved with CRISPR-Cas9 using pairs of single guide RNAs (sgRNAs) to target the flanking regions of a CRE. Here, I describe a single-step protocol to rapidly and inexpensively generate vectors co-expressing two sgRNAs, which allows re-usage of gRNAs oligonucleotides from one experimental design to another. This protocol is applicable to cloning sgRNAs into virtually any CRISPR-Cas9 backbone that allows cloning using Golden Gate, by adapting the primer design.


Assuntos
Sistemas CRISPR-Cas , Edição de Genes , Marcação de Genes , Vetores Genéticos/genética , Sequências Reguladoras de Ácido Nucleico , Deleção de Sequência , Clonagem Molecular , Ordem dos Genes , Marcação de Genes/métodos , Humanos , Células Secretoras de Insulina/metabolismo , RNA Guia/química , RNA Guia/genética
4.
Int J Mol Sci ; 22(15)2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-34360954

RESUMO

Ca2+-dependent gene regulation controls several functions to determine the fate of the cells. Proteins of the nuclear factor of activated T-cells (NFAT) family are Ca2+ sensitive transcription factors that control the cell growth, proliferation and insulin secretion in ß-cells. Translocation of NFAT proteins to the nucleus occurs in a sequence of events that starts with activating calmodulin-dependent phosphatase calcineurin in a Ca2+-dependent manner, which dephosphorylates the NFAT proteins and leads to their translocation to the nucleus. Here, we examined the role of IP3-generating agonists and near-UV light in the induction of NFATc3 migration to the nucleus in the pancreatic ß-cell line INS-1. Our results show that IP3 generation yields cytosolic Ca2+ rise and NFATc3 translocation. Moreover, near-UV light exposure generates reactive oxygen species (ROS), resulting in cytosolic Ca2+ spiking via the L-type Ca2+ channel and triggers NFATc3 translocation to the nucleus. Using the mitochondria as a Ca2+ buffering tool, we showed that ROS-induced cytosolic Ca2+ spiking, not the ROS themselves, was the triggering mechanism of nuclear import of NFATc3. Collectively, this study reveals the mechanism of near-UV light induced NFATc3 migration.


Assuntos
Sinalização do Cálcio , Fatores de Transcrição NFATC/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Raios Ultravioleta , Animais , Canais de Cálcio Tipo L/metabolismo , Linhagem Celular Tumoral , Inositol 1,4,5-Trifosfato/metabolismo , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/efeitos da radiação , Ratos
5.
Nat Commun ; 12(1): 4928, 2021 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-34389720

RESUMO

Diabetes results from a decline in functional pancreatic ß-cells, but the molecular mechanisms underlying the pathological ß-cell failure are poorly understood. Here we report that large-tumor suppressor 2 (LATS2), a core component of the Hippo signaling pathway, is activated under diabetic conditions and induces ß-cell apoptosis and impaired function. LATS2 deficiency in ß-cells and primary isolated human islets as well as ß-cell specific LATS2 ablation in mice improves ß-cell viability, insulin secretion and ß-cell mass and ameliorates diabetes development. LATS2 activates mechanistic target of rapamycin complex 1 (mTORC1), a physiological suppressor of autophagy, in ß-cells and genetic and pharmacological inhibition of mTORC1 counteracts the pro-apoptotic action of activated LATS2. We further show a direct interplay between Hippo and autophagy, in which LATS2 is an autophagy substrate. On the other hand, LATS2 regulates ß-cell apoptosis triggered by impaired autophagy suggesting an existence of a stress-sensitive multicomponent cellular loop coordinating ß-cell compensation and survival. Our data reveal an important role for LATS2 in pancreatic ß-cell turnover and suggest LATS2 as a potential therapeutic target to improve pancreatic ß-cell survival and function in diabetes.


Assuntos
Autofagia , Diabetes Mellitus/metabolismo , Células Secretoras de Insulina/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Animais , Linhagem Celular Tumoral , Sobrevivência Celular/genética , Células Cultivadas , Diabetes Mellitus/genética , Diabetes Mellitus/patologia , Humanos , Células Secretoras de Insulina/citologia , Alvo Mecanístico do Complexo 1 de Rapamicina/genética , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Serina-Treonina Quinases/genética , Interferência de RNA , Ratos , Transdução de Sinais/genética , Proteínas Supressoras de Tumor/genética
6.
Int J Mol Sci ; 22(16)2021 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-34445257

RESUMO

The production of pancreatic ß cells is the most challenging step for curing diabetes using next-generation treatments. Adult pancreatic endocrine cells are thought to be maintained by the self-duplication of differentiated cells, and pancreatic endocrine neogenesis can only be observed when the tissue is severely damaged. Experimentally, this can be performed using a method named partial duct ligation (PDL). As the success rate of PDL surgery is low because of difficulties in identifying the pancreatic duct, we previously proposed a method for fluorescently labeling the duct in live animals. Using this method, we performed PDL on neurogenin3 (Ngn3)-GFP transgenic mice to determine the origin of endocrine precursor cells and evaluate their potential to differentiate into multiple cell types. Ngn3-activated cells, which were marked with GFP, appeared after PDL operation. Because some GFP-positive cells were aligned proximally to the duct, we hypothesized that Ngn3-positive cells arise from the pancreatic duct. Therefore, we next developed an in vitro pancreatic duct culture system using Ngn3-GFP mice and examined whether Ngn3-positive cells emerge from this duct. We observed GFP expressions in ductal organoid cultures. GFP expressions were correlated with Ngn3 expressions and endocrine cell lineage markers. Interestingly, tuft cell markers were also correlated with GFP expressions. Our results demonstrate that in adult mice, Ngn3-positive endocrine precursor cells arise from the pancreatic ducts both in vivo and in vitro experiments indicating that the pancreatic duct could be a potential donor for therapeutic use.


Assuntos
Antígenos de Diferenciação/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Células Secretoras de Insulina/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Ductos Pancreáticos/metabolismo , Células-Tronco/metabolismo , Animais , Antígenos de Diferenciação/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Células Secretoras de Insulina/citologia , Camundongos , Camundongos Transgênicos , Proteínas do Tecido Nervoso/genética , Organoides/citologia , Organoides/metabolismo , Ductos Pancreáticos/citologia , Células-Tronco/citologia
7.
Int J Mol Sci ; 22(16)2021 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-34445300

RESUMO

Type 2 diabetes mellitus is a widespread medical condition, characterized by high blood glucose and inadequate insulin action, which leads to insulin resistance. Insulin resistance in insulin-responsive tissues precedes the onset of pancreatic ß-cell dysfunction. Multiple molecular and pathophysiological mechanisms are involved in insulin resistance. Insulin resistance is a consequence of a complex combination of metabolic disorders, lipotoxicity, glucotoxicity, and inflammation. There is ample evidence linking different mechanistic approaches as the cause of insulin resistance, but no central mechanism is yet described as an underlying reason behind this condition. This review combines and interlinks the defects in the insulin signal transduction pathway of the insulin resistance state with special emphasis on the AGE-RAGE-NF-κB axis. Here, we describe important factors that play a crucial role in the pathogenesis of insulin resistance to provide directionality for the events. The interplay of inflammation and oxidative stress that leads to ß-cell decline through the IAPP-RAGE induced ß-cell toxicity is also addressed. Overall, by generating a comprehensive overview of the plethora of mechanisms involved in insulin resistance, we focus on the establishment of unifying mechanisms to provide new insights for the future interventions of type 2 diabetes mellitus.


Assuntos
Resistência à Insulina/fisiologia , Insulina/metabolismo , Animais , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patologia , Humanos , Inflamação/metabolismo , Inflamação/patologia , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patologia , Estresse Oxidativo/fisiologia , Transdução de Sinais/fisiologia
8.
Int J Mol Sci ; 22(16)2021 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-34445304

RESUMO

Dysfunctional islets of Langerhans are a hallmark of type 2 diabetes (T2D). We hypothesize that differences in islet gene expression alternative splicing which can contribute to altered protein function also participate in islet dysfunction. RNA sequencing (RNAseq) data from islets of obese diabetes-resistant and diabetes-susceptible mice were analyzed for alternative splicing and its putative genetic and epigenetic modulators. We focused on the expression levels of chromatin modifiers and SNPs in regulatory sequences. We identified alternative splicing events in islets of diabetes-susceptible mice amongst others in genes linked to insulin secretion, endocytosis or ubiquitin-mediated proteolysis pathways. The expression pattern of 54 histones and chromatin modifiers, which may modulate splicing, were markedly downregulated in islets of diabetic animals. Furthermore, diabetes-susceptible mice carry SNPs in RNA-binding protein motifs and in splice sites potentially responsible for alternative splicing events. They also exhibit a larger exon skipping rate, e.g., in the diabetes gene Abcc8, which might affect protein function. Expression of the neuronal splicing factor Srrm4 which mediates inclusion of microexons in mRNA transcripts was markedly lower in islets of diabetes-prone compared to diabetes-resistant mice, correlating with a preferential skipping of SRRM4 target exons. The repression of Srrm4 expression is presumably mediated via a higher expression of miR-326-3p and miR-3547-3p in islets of diabetic mice. Thus, our study suggests that an altered splicing pattern in islets of diabetes-susceptible mice may contribute to an elevated T2D risk.


Assuntos
Processamento Alternativo/fisiologia , Diabetes Mellitus Tipo 2/genética , Ilhotas Pancreáticas/metabolismo , Processamento Alternativo/genética , Animais , Diabetes Mellitus Experimental/etiologia , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patologia , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patologia , Suscetibilidade a Doenças , Secreção de Insulina/genética , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patologia , Ilhotas Pancreáticas/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Obesidade/genética , Obesidade/metabolismo , Obesidade/patologia , Regulação para Cima/genética
9.
Int J Mol Sci ; 22(16)2021 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-34445786

RESUMO

Diabetes, and several diseases related to diabetes, including cancer, cardiovascular diseases and neurological disorders, represent one of the major ongoing threats to human life, becoming a true pandemic of the 21st century. Current treatment strategies for diabetes mainly involve promoting ß-cell differentiation, and one of the most widely studied targets for ß-cell regeneration is DYRK1A kinase, a member of the DYRK family. DYRK1A has been characterized as a key regulator of cell growth, differentiation, and signal transduction in various organisms, while further roles and substrates are the subjects of extensive investigation. The targets of interest in this review are implicated in the regulation of ß-cells through DYRK1A inhibition-through driving their transition from highly inefficient and death-prone populations into efficient and sufficient precursors of islet regeneration. Increasing evidence for the role of DYRK1A in diabetes progression and ß-cell proliferation expands the potential for pharmaceutical applications of DYRK1A inhibitors. The variety of new compounds and binding modes, determined by crystal structure and in vitro studies, may lead to new strategies for diabetes treatment. This review provides recent insights into the initial self-activation of DYRK1A by tyrosine autophosphorylation. Moreover, the importance of developing novel DYRK1A inhibitors and their implications for the treatment of diabetes are thoroughly discussed. The evolving understanding of DYRK kinase structure and function and emerging high-throughput screening technologies have been described. As a final point of this work, we intend to promote the term "diabetic kinome" as part of scientific terminology to emphasize the role of the synergistic action of multiple kinases in governing the molecular processes that underlie this particular group of diseases.


Assuntos
Diabetes Mellitus/tratamento farmacológico , Hipoglicemiantes/farmacologia , Células Secretoras de Insulina/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Tirosina Quinases/antagonistas & inibidores , Animais , Diabetes Mellitus/metabolismo , Humanos , Células Secretoras de Insulina/metabolismo
10.
Free Radic Biol Med ; 174: 135-143, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34363947

RESUMO

Aquaporin-8 (AQP8) is a peroxiporin, a transmembrane water and hydrogen peroxide (H2O2) transport protein expressed in the mitochondrial and plasma membranes of pancreatic ß-cells. AQP8 protein expression is low under physiological conditions, but it increases after cytokine exposure both, in vitro and in vivo, possibly related to a NF-κB consensus sequence in the promoter. AQP8 knockdown (KD) insulin-producing RINm5F cells are particularly susceptible to cytokine-mediated oxidative stress. Cytokine (a mixture of IL-1ß, TNF-α, and IFN-γ) treated AQP8 KD cells exhibited pronounced sensitivity to reactive oxygen and nitrogen species (ROS and RNS), resulting in a significant loss of ß-cell viability due to enhanced toxicity of the increased concentrations of H2O2 and hydroxyl radicals (●OH) in mitochondria of AQP8 KD cells. This viability loss went along with increased caspase activities, reduced nitrite concentration (representative of nitric oxide (NO●) accumulation) and increased lipid peroxidation. The explanation for the increased toxicity of the proinflammatory cytokines in AQP8 KD cells resides in the fact that efflux of the H2O2 generated during oxidative stress in the ß-cell mitochondria is hampered through the loss of the peroxiporin channels in the mitochondrial membranes of the AQP8 KD cells. The increased proinflammatory cytokine toxicity due to loss of AQP8 expression in the KD ß-cell mitochondria is thus the result of increased rates of apoptosis. This decreased cell viability is caused by increased levels of oxidative stress along with a ferroptosis-mediated cell death component due to decreased NO● generation.


Assuntos
Aquaporinas , Células Secretoras de Insulina , Animais , Citocinas/genética , Peróxido de Hidrogênio/metabolismo , Peróxido de Hidrogênio/toxicidade , Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Ratos
11.
Eur J Endocrinol ; 185(4): 565-576, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34374650

RESUMO

Objective: Progressive beta-cell dysfunction is a hallmark of type 2 diabetes (T2D). Increasing evidence indicates that over-stimulating proinsulin synthesis causes proinsulin misfolding and impairs insulin maturation and storage in db/db mice. However, defective insulin maturation in patients with T2D remains unknown. Methods: We examined intra-islet and intra-cellular distributions of proinsulin and insulin and proinsulin to insulin ratio in the islets of patients with T2D. The expression of transcription factor NKX6.1 and dedifferentiation marker ALDH1A3, as well as glucagon, were detected by immunofluorescence. Results: We identified a novel subgroup of beta cells expressing only proinsulin but not insulin. Importantly, significantly increased proinsulin positive and insulin negative (PI+/INS-) cells were evident in T2D, and this increase was strongly correlated with levels of hemoglobin A1C (HbA1c) in T2D and prediabetes. The percentages of beta cells expressing prohormone convertase 1/3 and carboxypeptidase E were not reduced. Indeed, while proinsulin displayed a higher degree of co-localization with the golgi markers GM130/TGN46 in control beta cells, it appeared to be more diffused within the cytoplasm and less co-localized with GM130/TGN46 in PI+/INS- cells. Furthermore, the key functional transcription factor NKX6.1 markedly decreased in the islets of T2D, especially in the cells with PI+/INS-. The decreased NKX6.1+/PI+/INS+ was strongly correlated with levels of HbA1c in T2D. Almost all PI+/INS- cells showed absence of NKX6.1. Moreover, the percentages of PI+/INS- cells expressing ALDH1A3 were elevated along with an increased acquisition of glucagon immunostaining. Conclusion: Our data demonstrate defective insulin maturation in patients with T2D.


Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Proinsulina/metabolismo , Processamento de Proteína Pós-Traducional/fisiologia , Adulto , Aldeído Oxirredutases/metabolismo , Estudos de Casos e Controles , Desdiferenciação Celular/fisiologia , China , Diabetes Mellitus Tipo 2/patologia , Feminino , Glucagon/metabolismo , Proteínas de Homeodomínio/metabolismo , Humanos , Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patologia , Células Secretoras de Insulina/fisiologia , Masculino , Pessoa de Meia-Idade , Estado Pré-Diabético/metabolismo , Estado Pré-Diabético/patologia
12.
Int J Mol Sci ; 22(15)2021 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-34360548

RESUMO

Keratin (K) 7 is an intermediate filament protein expressed in ducts and glands of simple epithelial organs and in urothelial tissues. In the pancreas, K7 is expressed in exocrine ducts, and apico-laterally in acinar cells. Here, we report K7 expression with K8 and K18 in the endocrine islets of Langerhans in mice. K7 filament formation in islet and MIN6 ß-cells is dependent on the presence and levels of K18. K18-knockout (K18‒/‒) mice have undetectable islet K7 and K8 proteins, while K7 and K18 are downregulated in K8‒/‒ islets. K7, akin to F-actin, is concentrated at the apical vertex of ß-cells in wild-type mice and along the lateral membrane, in addition to forming a fine cytoplasmic network. In K8‒/‒ ß-cells, apical K7 remains, but lateral keratin bundles are displaced and cytoplasmic filaments are scarce. Islet K7, rather than K8, is increased in K18 over-expressing mice and the K18-R90C mutation disrupts K7 filaments in mouse ß-cells and in MIN6 cells. Notably, islet K7 filament networks significantly increase and expand in the perinuclear regions when examined in the streptozotocin diabetes model. Hence, K7 represents a significant component of the murine islet keratin network and becomes markedly upregulated during experimental diabetes.


Assuntos
Diabetes Mellitus Experimental/patologia , Células Secretoras de Insulina/patologia , Queratina-18/metabolismo , Queratina-7/metabolismo , Queratina-8/metabolismo , Animais , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/metabolismo , Regulação da Expressão Gênica , Células Secretoras de Insulina/metabolismo , Queratina-18/genética , Queratina-7/genética , Queratina-8/genética , Camundongos , Camundongos Knockout , Regulação para Cima
13.
Nat Commun ; 12(1): 5074, 2021 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-34417463

RESUMO

ß cells may participate and contribute to their own demise during Type 1 diabetes (T1D). Here we report a role of their expression of Tet2 in regulating immune killing. Tet2 is induced in murine and human ß cells with inflammation but its expression is reduced in surviving ß cells. Tet2-KO mice that receive WT bone marrow transplants develop insulitis but not diabetes and islet infiltrates do not eliminate ß cells even though immune cells from the mice can transfer diabetes to NOD/scid recipients. Tet2-KO recipients are protected from transfer of disease by diabetogenic immune cells.Tet2-KO ß cells show reduced expression of IFNγ-induced inflammatory genes that are needed to activate diabetogenic T cells. Here we show that Tet2 regulates pathologic interactions between ß cells and immune cells and controls damaging inflammatory pathways. Our data suggests that eliminating TET2 in ß cells may reduce activating pathologic immune cells and killing of ß cells.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Diabetes Mellitus Tipo 1/patologia , Inflamação/patologia , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patologia , Proteínas Proto-Oncogênicas/metabolismo , Animais , Sequência de Bases , Citotoxicidade Imunológica , Diabetes Mellitus Tipo 1/genética , Diabetes Mellitus Tipo 1/imunologia , Progressão da Doença , Feminino , Humanos , Imunidade , Inflamação/genética , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , Linfócitos T/imunologia , Transcrição Genética
14.
Int J Mol Sci ; 22(12)2021 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-34198511

RESUMO

The insulin receptor (IR) is critically involved in maintaining glucose homeostasis. It undergoes proteolytic cleavage by proprotein convertases, which is an essential step for its activation. The importance of the insulin receptor in liver is well established, but its role in pancreatic ß cells is still controversial. In this study, we investigated the cleavage of the IR by the proprotein convertase FURIN in ß cells and hepatocytes, and the contribution of the IR in pancreatic ß cells and liver to glucose homeostasis. ß-cell-specific Furin knockout (ßFurKO) mice were glucose intolerant, but liver-specific Furin knockout (LFurKO) mice were normoglycemic. Processing of the IR was blocked in ßFurKO cells, but unaffected in LFurKO mice. Most strikingly, glucose homeostasis in ß-cell-specific IR knockout (ßIRKO) mice was normal in younger mice (up to 20 weeks), and only mildly affected in older mice (24 weeks). In conclusion, FURIN cleaves the IR non-redundantly in ß cells, but redundantly in liver. Furthermore, we demonstrated that the IR in ß cells plays a limited role in glucose homeostasis.


Assuntos
Furina/deficiência , Glucose/metabolismo , Células Secretoras de Insulina/metabolismo , Fígado/metabolismo , Receptor de Insulina/metabolismo , Animais , Furina/metabolismo , Intolerância à Glucose/metabolismo , Intolerância à Glucose/patologia , Homeostase , Camundongos Knockout , Proteólise , Receptor de Insulina/deficiência , Transdução de Sinais
15.
Nutrients ; 13(7)2021 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-34209449

RESUMO

Interactions between endocrine α and ß cells are critical to their secretory function in vivo. The interactions are highly regulated, although yet to be fully understood. In this study, we aim to assess the impact of α and ß cell co-culture on hormone secretion. Mouse clonal cell lines α-TC6-1 (α cell line) and MIN-6 (ß cell line) were cultured independently or in combination in a medium containing 5.5, 11.1, or 25 mM glucose, respectively. After 72 h, hormone release was measured using insulin and glucagon secretion assays, the cell distribution was visualized by inverted microscopy and an immunocytochemistry assay, and changes in gene expressions were assessed using the RT-PCR technique. The co-culture of the two cell lines caused a decrease in glucagon secretion from α-TC1-6 cells, while no effect on insulin secretion from MIN-6 cells was revealed. Both types of cells were randomly scattered throughout the culture flask, unlike in mice islets in vivo where ß cells cluster in the core and α cells are localized at the periphery. During the α-ß cell co-culture, the gene expression of glucagon (Gcg) decreased significantly. We conclude that islet ß cells suppress glucagon secretion from α cells, apparently via direct cell-to-cell contact, of which the molecular mechanism needs further verification.


Assuntos
Comunicação Celular , Células Secretoras de Glucagon/citologia , Células Secretoras de Glucagon/metabolismo , Glucagon/metabolismo , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/metabolismo , Animais , Sobrevivência Celular/efeitos dos fármacos , Regulação da Expressão Gênica , Glucose/farmacologia , Secreção de Insulina , Camundongos
16.
Sci Transl Med ; 13(604)2021 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-34321322

RESUMO

Type 2 diabetes (T2D) is a metabolic disorder characterized by hyperglycemia, hyperinsulinemia, and insulin resistance (IR). During the early phase of T2D, insulin synthesis and secretion by pancreatic ß cells is enhanced, which can lead to proinsulin misfolding that aggravates endoplasmic reticulum (ER) protein homeostasis in ß cells. Moreover, increased circulating insulin may contribute to fatty liver disease. Medical interventions aimed at alleviating ER stress in ß cells while maintaining optimal insulin secretion are therefore an attractive therapeutic strategy for T2D. Previously, we demonstrated that germline Chop gene deletion preserved ß cells in high-fat diet (HFD)-fed mice and in leptin receptor-deficient db/db mice. In the current study, we further investigated whether targeting Chop/Ddit3 specifically in murine ß cells conferred therapeutic benefits. First, we showed that Chop deletion in ß cells alleviated ß cell ER stress and delayed glucose-stimulated insulin secretion (GSIS) in HFD-fed mice. Second, ß cell-specific Chop deletion prevented liver steatosis and hepatomegaly in aged HFD-fed mice without affecting basal glucose homeostasis. Third, we provide mechanistic evidence that Chop depletion reduces ER Ca2+ buffering capacity and modulates glucose-induced islet Ca2+ oscillations, leading to transcriptional changes of ER chaperone profile ("ER remodeling"). Last, we demonstrated that a GLP1-conjugated Chop antisense oligonucleotide strategy recapitulated the reduction in liver triglycerides and pancreatic insulin content. In summary, our results demonstrate that Chop depletion in ß cells provides a therapeutic strategy to alleviate dysregulated insulin secretion and consequent fatty liver disease in T2D.


Assuntos
Diabetes Mellitus Tipo 2 , Fígado Gorduroso , Células Secretoras de Insulina , Animais , Diabetes Mellitus Tipo 2/metabolismo , Dieta Hiperlipídica/efeitos adversos , Estresse do Retículo Endoplasmático , Insulina/metabolismo , Secreção de Insulina , Células Secretoras de Insulina/metabolismo , Camundongos , Camundongos Endogâmicos C57BL
17.
Nat Commun ; 12(1): 4458, 2021 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-34294685

RESUMO

The cellular identity of pancreatic polypeptide (Ppy)-expressing γ-cells, one of the rarest pancreatic islet cell-type, remains elusive. Within islets, glucagon and somatostatin, released respectively from α- and δ-cells, modulate the secretion of insulin by ß-cells. Dysregulation of insulin production raises blood glucose levels, leading to diabetes onset. Here, we present the genetic signature of human and mouse γ-cells. Using different approaches, we identified a set of genes and pathways defining their functional identity. We found that the γ-cell population is heterogeneous, with subsets of cells producing another hormone in addition to Ppy. These bihormonal cells share identity markers typical of the other islet cell-types. In mice, Ppy gene inactivation or conditional γ-cell ablation did not alter glycemia nor body weight. Interestingly, upon ß-cell injury induction, γ-cells exhibited gene expression changes and some of them engaged insulin production, like α- and δ-cells. In conclusion, we provide a comprehensive characterization of γ-cells and highlight their plasticity and therapeutic potential.


Assuntos
Insulina/biossíntese , Células Secretoras de Polipeptídeo Pancreático/metabolismo , Polipeptídeo Pancreático/metabolismo , Precursores de Proteínas/metabolismo , Animais , Glicemia/metabolismo , Peso Corporal , Linhagem da Célula/genética , Feminino , Técnicas de Introdução de Genes , Humanos , Células Secretoras de Insulina/classificação , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Pâncreas/citologia , Pâncreas/embriologia , Pâncreas/crescimento & desenvolvimento , Polipeptídeo Pancreático/deficiência , Polipeptídeo Pancreático/genética , Células Secretoras de Polipeptídeo Pancreático/classificação , Células Secretoras de Polipeptídeo Pancreático/citologia , Gravidez , RNA-Seq
18.
Methods Mol Biol ; 2312: 35-57, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34228283

RESUMO

Diabetes mellitus is a complex metabolic disease characterized by chronically deregulated blood-glucose levels. To restore glucose homeostasis, therapeutic strategies allowing well-controlled production and release of insulinogenic hormones into the blood circulation are required. In this chapter, we describe how mammalian cells can be engineered for applications in diabetes treatment. While closed-loop control systems provide automated and self-sufficient synchronization of glucose sensing and drug production, drug production in open-loop control systems is engineered to depend on exogenous user-defined trigger signals. Rational, robust, and reliable manufacture practices for mammalian cell engineering are essential for industrial-scale mass-production in view of clinical and commercial applications.


Assuntos
Técnicas Biossensoriais , Glicemia/metabolismo , Engenharia Celular , Diabetes Mellitus Experimental/terapia , Terapia Genética , Peptídeo 1 Semelhante ao Glucagon/genética , Células Secretoras de Insulina/transplante , Insulina/genética , Biologia Sintética , Animais , Biomarcadores/sangue , Encapsulamento de Células , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Experimental/diagnóstico , Diabetes Mellitus Experimental/genética , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Células HEK293 , Homeostase , Humanos , Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Transfecção
19.
Int J Mol Sci ; 22(13)2021 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-34201511

RESUMO

Diabetes is a metabolic disease that involves the death or dysfunction of the insulin-secreting ß cells in the pancreas. Consequently, most diabetes research is aimed at understanding the molecular and cellular bases of pancreatic development, islet formation, ß-cell survival, and insulin secretion. Complex interactions of signaling pathways and transcription factor networks regulate the specification, growth, and differentiation of cell types in the developing pancreas. Many of the same regulators continue to modulate gene expression and cell fate of the adult pancreas. The transcription factor NEUROD1 is essential for the maturation of ß cells and the expansion of the pancreatic islet cell mass. Mutations of the Neurod1 gene cause diabetes in humans and mice. However, the different aspects of the requirement of NEUROD1 for pancreas development are not fully understood. In this study, we investigated the role of NEUROD1 during the primary and secondary transitions of mouse pancreas development. We determined that the elimination of Neurod1 impairs the expression of key transcription factors for α- and ß-cell differentiation, ß-cell proliferation, insulin production, and islets of Langerhans formation. These findings demonstrate that the Neurod1 deletion altered the properties of α and ß endocrine cells, resulting in severe neonatal diabetes, and thus, NEUROD1 is required for proper activation of the transcriptional network and differentiation of functional α and ß cells.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Ilhotas Pancreáticas/citologia , Pâncreas/citologia , Pâncreas/embriologia , Animais , Animais Recém-Nascidos , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Diferenciação Celular , Linhagem da Célula , Proliferação de Células , Diabetes Mellitus/genética , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Insulina/metabolismo , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/ultraestrutura , Camundongos Endogâmicos C57BL , Camundongos Transgênicos
20.
Cell Mol Life Sci ; 78(16): 6017-6031, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34245311

RESUMO

A precondition for efficient proinsulin export from the endoplasmic reticulum (ER) is that proinsulin meets ER quality control folding requirements, including formation of the Cys(B19)-Cys(A20) "interchain" disulfide bond, facilitating formation of the Cys(B7)-Cys(A7) bridge. The third proinsulin disulfide, Cys(A6)-Cys(A11), is not required for anterograde trafficking, i.e., a "lose-A6/A11" mutant [Cys(A6), Cys(A11) both converted to Ser] is well secreted. Nevertheless, an unpaired Cys(A11) can participate in disulfide mispairings, causing ER retention of proinsulin. Among the many missense mutations causing the syndrome of Mutant INS gene-induced Diabetes of Youth (MIDY), all seem to exhibit perturbed proinsulin disulfide bond formation. Here, we have examined a series of seven MIDY mutants [including G(B8)V, Y(B26)C, L(A16)P, H(B5)D, V(B18)A, R(Cpep + 2)C, E(A4)K], six of which are essentially completely blocked in export from the ER in pancreatic ß-cells. Three of these mutants, however, must disrupt the Cys(A6)-Cys(A11) pairing to expose a critical unpaired cysteine thiol perturbation of proinsulin folding and ER export, because when introduced into the proinsulin lose-A6/A11 background, these mutants exhibit native-like disulfide bonding and improved trafficking. This maneuver also ameliorates dominant-negative blockade of export of co-expressed wild-type proinsulin. A growing molecular understanding of proinsulin misfolding may permit allele-specific pharmacological targeting for some MIDY mutants.


Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Proinsulina/metabolismo , Adolescente , Células Cultivadas , Cisteína/genética , Cisteína/metabolismo , Diabetes Mellitus Tipo 2/genética , Dissulfetos/metabolismo , Retículo Endoplasmático/genética , Retículo Endoplasmático/metabolismo , Humanos , Insulina/genética , Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Mutação de Sentido Incorreto/genética , Proinsulina/genética , Dobramento de Proteína
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