RESUMEN
Pancreatic ßcells are the only cells that synthesize insulin to regulate blood glucose levels. Various conditions can affect the mass of pancreatic ßcells and decrease insulin levels. Diabetes mellitus is a disease characterized by insulin resistance and chronic hyperglycemia, mainly due to the loss of pancreatic ßcells caused by an increase in the rate of apoptosis. Additionally, hyperglycemia has a toxic effect on ßcells. Although the precise mechanism of glucotoxicity is not fully understood, several mechanisms have been proposed. The most prominent changes are increases in reactive oxygen species, the loss of mitochondrial membrane potential and the activation of the intrinsic pathway of apoptosis due to p53. The present review analyzed the location of p53 in the cytoplasm, mitochondria and nucleus in terms of posttranslational modifications, including phosphorylation, OGlcNAcylation and polyADPribosylation, under hyperglycemic conditions. These modifications protect p53 from degradation by the proteasome and, in turn, enable it to regulate the intrinsic pathway of apoptosis through the regulation of antiapoptotic and proapoptotic elements. Degradation of p53 occurs in the proteasome and depends on its ubiquitination by Mdm2. Understanding the mechanisms that activate the death of pancreatic ßcells will allow the proposal of treatment alternatives to prevent the decrease in pancreatic ßcells.
Asunto(s)
Apoptosis , Diabetes Mellitus Tipo 2 , Células Secretoras de Insulina , Procesamiento Proteico-Postraduccional , Proteína p53 Supresora de Tumor , Proteína p53 Supresora de Tumor/metabolismo , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patología , Humanos , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patología , AnimalesRESUMEN
Diabetes mellitus, a chronic and non-transmissible disease, triggers a wide range of micro- and macrovascular complications. The differentiation of pancreatic ß-like cells (PßLCs) from induced pluripotent stem cells (iPSCs) offers a promising avenue for regenerative medicine aimed at treating diabetes. Current differentiation protocols strive to emulate pancreatic embryonic development by utilizing cytokines and small molecules at specific doses to activate and inhibit distinct molecular signaling pathways, directing the differentiation of iPSCs into pancreatic ß cells. Despite significant progress and improved protocols, the full spectrum of molecular signaling pathways governing pancreatic development and the physiological characteristics of the differentiated cells are not yet fully understood. Here, we report a specific combination of cofactors and small molecules that successfully differentiate iPSCs into PßLCs. Our protocol has shown to be effective, with the resulting cells exhibiting key functional properties of pancreatic ß cells, including the expression of crucial molecular markers (pdx1, nkx6.1, ngn3) and the capability to secrete insulin in response to glucose. Furthermore, the addition of vitamin C and retinoic acid in the final stages of differentiation led to the overexpression of specific ß cell genes.
Asunto(s)
Ácido Ascórbico , Diferenciación Celular , Diabetes Mellitus , Células Madre Pluripotentes Inducidas , Células Secretoras de Insulina , Tretinoina , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/citología , Ácido Ascórbico/farmacología , Células Madre Pluripotentes Inducidas/metabolismo , Células Madre Pluripotentes Inducidas/citología , Células Madre Pluripotentes Inducidas/efectos de los fármacos , Tretinoina/farmacología , Diferenciación Celular/efectos de los fármacos , Humanos , Diabetes Mellitus/metabolismo , Proteínas de Homeodominio/metabolismo , Proteínas de Homeodominio/genética , Transducción de Señal/efectos de los fármacos , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Transactivadores/metabolismo , Transactivadores/genética , Insulina/metabolismo , Proteínas del Tejido NerviosoRESUMEN
The nerve growth factor (NGF) participates in cell survival and glucose-stimulated insulin secretion (GSIS) processes in rat adult beta cells. GSIS is a complex process in which metabolic events and ionic channel activity are finely coupled. GLUT2 and glucokinase (GK) play central roles in GSIS by regulating the rate of the glycolytic pathway. The biphasic release of insulin upon glucose stimulation characterizes mature adult beta cells. On the other hand, beta cells obtained from neonatal, suckling, and weaning rats are considered immature because they secrete low levels of insulin and do not increase insulin secretion in response to high glucose. The weaning of rats (at postnatal day 20 in laboratory conditions) involves a dietary transition from maternal milk to standard chow. It is characterized by increased basal plasma glucose levels and insulin levels, which we consider physiological insulin resistance. On the other hand, we have observed that incubating rat beta cells with NGF increases GSIS by increasing calcium currents in neonatal cells. In this work, we studied the effects of NGF on the regulation of cellular distribution and activity of GLUT2 and GK to explore its potential role in the maturation of GSIS in beta cells from P20 rats. Pancreatic islet cells from both adult and P20 rats were isolated and incubated with 5.6 mM or 15.6 mM glucose with and without NGF for 4 hours. Specific immunofluorescence assays were conducted following the incubation period to detect insulin and GLUT2. Additionally, we measured glucose uptake, glucokinase activity, and insulin secretion assays at 5.6 mM or 15.6 mM glucose concentrations. We observed an age-dependent variation in the distribution of GLUT2 in pancreatic beta cells and found that glucose plays a regulatory role in GLUT2 distribution independently of age. Moreover, NGF increases GLUT2 abundance, glucose uptake, and GSIS in P20 beta cells and GK activity in adult beta cells. Our results suggest that besides increasing calcium currents, NGF regulates metabolic components of the GSIS, thereby contributing to the maturation process of pancreatic beta cells.
Asunto(s)
Glucoquinasa , Transportador de Glucosa de Tipo 2 , Glucosa , Células Secretoras de Insulina , Factor de Crecimiento Nervioso , Animales , Masculino , Ratas , Células Cultivadas , Glucoquinasa/metabolismo , Glucosa/metabolismo , Transportador de Glucosa de Tipo 2/metabolismo , Insulina/metabolismo , Secreción de Insulina/efectos de los fármacos , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/efectos de los fármacos , Factor de Crecimiento Nervioso/metabolismo , Factor de Crecimiento Nervioso/farmacología , Ratas WistarRESUMEN
BACKGROUND: Diabetes mellitus (DM) is a global epidemic with increasing incidences. DM is a metabolic disease associated with chronic hyperglycemia. Aside from conventional treatments, there is no clinically approved cure for DM up till now. Differentiating mesenchymal stem cells (MSCs) into insulin-producing cells (IPCs) is a promising approach for curing DM. Our study was conducted to investigate the effect of DM on MSCs differentiation into IPCs in vivo and in vitro. METHODS: We isolated adipose-derived mesenchymal stem cells (Ad-MSCs) from the epididymal fat of normal and STZ-induced diabetic Sprague-Dawley male rats. Afterwards, the in vitro differentiation of normal-Ad-MSCs (N-Ad-MSCs) and diabetic-Ad-MSCs (DM-Ad-MSCs) into IPCs was compared morphologically then through determining the gene expression of ß-cell markers including neurogenin-3 (Ngn-3), homeobox protein (Nkx6.1), musculoaponeurotic fibrosarcoma oncogene homolog A (MafA), and insulin-1 (Ins-1) and eventually, through performing glucose-stimulated insulin secretion test (GSIS). Finally, the therapeutic potential of N-Ad-MSCs and DM-Ad-MSCs transplantation was compared in vivo in STZ-induced diabetic animals. RESULTS: Our results showed no significant difference in the characteristics of N-Ad-MSCs and DM-Ad-MSCs. However, we demonstrated a significant difference in their abilities to differentiate into IPCs in vitro morphologically in addition to ß-cell markers expression, and functional assessment via GSIS test. Furthermore, the abilities of both Ad-MSCs to control hyperglycemia in diabetic rats in vivo was assessed through measuring fasting blood glucose (FBGs), body weight (BW), histopathological examination of both pancreas and liver and immunoexpression of insulin in pancreata of study groups. CONCLUSION: Our findings reveal the effectiveness of N-Ad-MSCs in differentiating into IPCs in vitro and controlling the hyperglycemia of STZ-induced diabetic rats in vivo compared to DM-Ad-MSCs.
Asunto(s)
Diferenciación Celular , Diabetes Mellitus Experimental , Células Secretoras de Insulina , Insulina , Células Madre Mesenquimatosas , Ratas Sprague-Dawley , Animales , Diferenciación Celular/fisiología , Diabetes Mellitus Experimental/terapia , Masculino , Células Secretoras de Insulina/metabolismo , Insulina/metabolismo , Ratas , Trasplante de Células Madre Mesenquimatosas/métodos , Células Cultivadas , Estreptozocina , Glucemia/análisisRESUMEN
The increasing global prevalence and associated comorbidities need innovative approaches for type 2 diabetes mellitus (T2DM) prevention and treatment. Genetics contributes significantly to T2DM susceptibility, and genetic counseling is significant in detecting and informing people about the diabetic risk. T2DM is also intricately linked to overnutrition and obesity, and nutritional advising is beneficial to mitigate diabetic evolution. However, manipulating pancreatic cell plasticity and transdifferentiation could help beta cell regeneration and glucose homeostasis, effectively contributing to the antidiabetic fight. Targeted modulation of transcription factors is highlighted for their roles in various aspects of pancreatic cell differentiation and function, inducing non-beta cells' conversion into functional beta cells (responsive to glucose). In addition, pharmacological interventions targeting specific receptors and pathways might facilitate cell transdifferentiation aiming to maintain or increase beta cell mass and function. However, the mechanisms underlying cellular reprogramming are not yet well understood. The present review highlights the primary transcriptional factors in the endocrine pancreas, focusing on transdifferentiation as a primary mechanism. Therefore, islet cell reprogramming, converting one cell type to another and transforming non-beta cells into insulin-producing cells, depends, among others, on transcription factors. It is a promising fact that new transcription factors are discovered every day, and their actions on pancreatic islet cells are revealed. Exploring these pathways associated with pancreatic development and islet endocrine cell differentiation could unravel the molecular intricacies underlying transdifferentiation processes, exploring novel therapeutic strategies to treat diabetes. The medical use of this biotechnology is expected to be achievable within a short time.
Asunto(s)
Transdiferenciación Celular , Diabetes Mellitus Tipo 2 , Células Secretoras de Insulina , Humanos , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/citología , Diabetes Mellitus Tipo 2/terapia , Diabetes Mellitus Tipo 2/metabolismo , Animales , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Diferenciación Celular , Páncreas/metabolismo , Páncreas/patologíaRESUMEN
Recent studies have shown that maternal vitamin D deficiency (VDD) causes long-term metabolic changes in offspring. However, little is known about the impact of maternal VDD on offspring endocrine pancreas development and insulin secretion in the adult life of male and female animals. Female rats (Wistar Hannover) were fed either control (1000 IU Vitamin D3/kg), VDD (0 IU Vitamin D3/kg), or a Ca2+-enriched VDD diet (0 IU Vitamin D3/kg + Ca2+ and P/kg) for 6 weeks and during gestation and lactation. At weaning, VDD status was confirmed based on low serum calcidiol levels in dams and pups. Next, male and female offspring were randomly separated and fed a standard diet for up to 90 days. At this age, serum calcidiol levels were restored to normal levels in all groups, but serum insulin levels were decreased in VDD males without affecting glucagon levels, glycemia, or glucose tolerance. Islets isolated from VDD males showed lower insulin secretion in response to different glucose concentrations, but this effect was not observed in VDD females. Furthermore, VDD males, but not females, showed a smaller total pancreatic islet area and lower ß cell mass, an effect that was accompanied by reduced gene expression of Ins1, Ins2, Pdx1, and SLC2A2. The decrease in Pdx1 expression was not related to the methylation profile of the promoter region of this gene. Most of these effects were observed in the male VDD+Ca2+ group, indicating that the effects were not due to alterations in Ca2+ metabolism. These data show that maternal VDD selectively impairs the morphology and function of ß cells in adult male offspring rats and that female offspring are fully protected from these deleterious effects.
Asunto(s)
Células Secretoras de Insulina , Insulina , Ratas Wistar , Deficiencia de Vitamina D , Animales , Femenino , Células Secretoras de Insulina/metabolismo , Masculino , Deficiencia de Vitamina D/metabolismo , Ratas , Embarazo , Insulina/sangre , Insulina/metabolismo , Efectos Tardíos de la Exposición Prenatal/metabolismo , Efectos Tardíos de la Exposición Prenatal/etiología , Factores Sexuales , Secreción de InsulinaRESUMEN
Lifestyle modifications, metformin, and linagliptin reduce the incidence of type 2 diabetes (T2D) in people with prediabetes. The gut microbiota (GM) may enhance such interventions' efficacy. We determined the effect of linagliptin/metformin (LM) vs metformin (M) on GM composition and its relationship to insulin sensitivity (IS) and pancreatic ß-cell function (Pßf) in patients with prediabetes. A cross-sectional study was conducted at different times: basal, six, and twelve months in 167 Mexican adults with prediabetes. These treatments increased the abundance of GM SCFA-producing bacteria M (Fusicatenibacter and Blautia) and LM (Roseburia, Bifidobacterium, and [Eubacterium] hallii group). We performed a mediation analysis with structural equation models (SEM). In conclusion, M and LM therapies improve insulin sensitivity and Pßf in prediabetics. GM is partially associated with these improvements since the SEM models suggest a weak association between specific bacterial genera and improvements in IS and Pßf.
Asunto(s)
Microbioma Gastrointestinal , Linagliptina , Metformina , Estado Prediabético , Humanos , Metformina/farmacología , Metformina/uso terapéutico , Microbioma Gastrointestinal/efectos de los fármacos , Estado Prediabético/tratamiento farmacológico , Estado Prediabético/microbiología , Masculino , Femenino , Persona de Mediana Edad , Estudios Transversales , Linagliptina/uso terapéutico , Linagliptina/farmacología , Hipoglucemiantes/farmacología , Hipoglucemiantes/uso terapéutico , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Diabetes Mellitus Tipo 2/microbiología , Diabetes Mellitus Tipo 2/metabolismo , Resistencia a la Insulina , Adulto , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/metabolismo , AncianoRESUMEN
Impaired insulin production and/or secretion by pancreatic beta cells can lead to high blood glucose levels and type 2 diabetes (T2D). Therefore, investigating new proteins involved in beta cell response to stress conditions could be useful in finding new targets for therapeutic approaches. KH-type splicing regulatory protein (KSRP) is a protein usually involved in gene expression due to its role in post-transcriptional regulation. Although there are studies describing the important role of KSRP in tissues closely related to glucose homeostasis, its effect on pancreatic beta cells has not been explored so far. Pancreatic islets from diet-induced obese mice (C57BL/6JUnib) were used to determine KSRP expression and we also performed in vitro experiments exposing INS-1E cells (pancreatic beta cell line) to different stressors (palmitate or cyclopiazonic acid-CPA) to induce cellular dysfunction. Here we show that KSRP expression is reduced in all the beta cell dysfunction models tested. In addition, when manipulated to knock down KSRP, beta cells exhibited increased death and impaired insulin secretion, whereas KSRP overexpression prevented cell death and increased insulin secretion. Taken together, our findings suggest that KSRP could be an important target to protect beta cells from impaired functioning and death.
Asunto(s)
Diabetes Mellitus Tipo 2 , Células Secretoras de Insulina , Islotes Pancreáticos , Animales , Ratones , Supervivencia Celular , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Islotes Pancreáticos/metabolismo , Ratones Endogámicos C57BLRESUMEN
Pancreatic ß-cells are equipped with the molecular machinery allowing them to respond to high glucose levels in the form of electrical activity and Ca2+ oscillations. These oscillations drive insulin secretion. Two key ionic mechanisms involved in this response are the Store-Operated Current and the current through ATP-dependent K+ channels. Both currents have been shown to be regulated by the protein STIM1, but this dual regulation by STIM1 has not been studied before. In this paper, we use mathematical modelling to gain insight into the role of STIM1 in the ß-cell response. We extended a previous ß-cell model to include the dynamics of STIM1 and described the dependence of the ATP-dependent K+ current on STIM1. Our simulations suggest that the total concentration of STIM1 modifies the bursting frequency, the burst duration and the intracellular Ca2+ levels. These results are in good agreement with experimental reports, and the contribution of the studied currents to electrical activity and Ca2+ dynamics is discussed. The model predicts that in the absence of STIM1 the excitability of the plasma membrane increases and that the glucose threshold for electrical activity is shifted to lower concentrations. These computational predictions may be related to impaired insulin secretion under conditions of reduced STIM1 in the diabetic state.
Asunto(s)
Células Secretoras de Insulina , Molécula de Interacción Estromal 1 , Adenosina Trifosfato/metabolismo , Calcio/metabolismo , Señalización del Calcio , Membrana Celular/metabolismo , Glucosa/metabolismo , Secreción de Insulina , Células Secretoras de Insulina/metabolismo , Molécula de Interacción Estromal 1/metabolismo , HumanosRESUMEN
Vertical sleeve gastrectomy (VSG) restores glucose homeostasis in obese mice and humans. In addition, the increased fibroblast growth factor (FGF)15/19 circulating level postsurgery has been implicated in this effect. However, the impact of FGF15/19 on pancreatic islets remains unclear. Using a diet-induced obese mice model, we demonstrate that VSG attenuates insulin hypersecretion in isolated pancreatic islets, likely due to morphological alterations in the endocrine pancreas such as reduction in islet, ß-cell, and α-cell mass. In addition, VSG relieves gene expression of endoplasmic reticulum (ER) stress and inflammation markers in islets from obese mice. Incubation of INS-1E ß-cells with serum from obese mice induced dysfunction and cell death, whereas these conditions were not induced with serum from obese mice submitted to VSG, implicating the involvement of a humoral factor. Indeed, VSG increased FGF15 circulating levels in obese mice, as well as the expression of FGF receptor 1 (Fgfr1) and its coreceptor ß-klotho (Klb), both in pancreatic islets from VSG mice and in INS-1E cells treated with the serum from these mice. Moreover, exposing INS-1E cells to an FGFR inhibitor abolished the effects of VSG serum on insulin secretion and cell death. Also, recombinant FGF19 prevents INS-1E cells from dysfunction and death induced by serum from obese mice. These findings indicate that the amelioration of glucose-insulin homeostasis promoted by VSG is mediated, at least in part, by FGF15/19. Therefore, approaches promoting FGF15/19 release or action may restore pancreatic islet function in obesity.NEW & NOTEWORTHY Vertical sleeve gastrectomy (VSG) decreases insulin secretion, endoplasmic reticulum (ER) stress, and inflammation in pancreatic islets from obese mice. In addition, VSG increased fibroblast growth factor (FGF)15 circulating levels in obese mice, as well as the expression of FGF receptor 1 (Fgfr1) and its coreceptor ß-klotho (Klb), both in pancreatic islets from VSG mice and in INS-1E ß-cells treated with the serum from these mice. Serum from operated mice protects INS-1E cells from dysfunction and apoptosis, which was mediated by FGF15/19.
Asunto(s)
Células Secretoras de Insulina , Insulina , Ratones , Humanos , Animales , Insulina/metabolismo , Ratones Obesos , Células Secretoras de Insulina/metabolismo , Glucosa/metabolismo , Receptores de Factores de Crecimiento de Fibroblastos/metabolismo , Factores de Crecimiento de Fibroblastos/metabolismo , Gastrectomía , Inflamación/metabolismo , HomeostasisRESUMEN
Obesity and type 2 diabetes mellitus (T2DM) cause morphofunctional alterations in pancreatic islet alpha and beta cells. Therefore, we hypothesize that the new GLP-1/Glucagon receptor dual agonist cotadutide may benefit islet cell arrangement and function. Twelve-week-old C57BL/6 male mice were fed a control diet (C, 10 % kJ fat) or a high-fat diet (HF, 50 % kJ fat) for ten weeks. Then, the animals were divided into four groups for an additional 30 days and daily treated with subcutaneous cotadutide (30 nmol/kg) or vehicle: C, CC (control+cotadutide), HF, and HFC (high-fat+cotadutide). Cotadutide led to weight loss and reduced insulin resistance in the HFC group, increasing insulin receptor substrate 1 and solute carrier family 2 gene expressions in isolated islets. Also, cotadutide enhanced transcriptional factors related to islet cell transdifferentiation, decreasing aristaless-related homeobox and increasing the paired box 4 and 6, pancreatic and duodenal homeobox 1, v-maf musculoaponeurotic fibrosarcoma oncogene family protein A, neurogenin 3, and neurogenic differentiation 1. In addition, cotadutide improved the proliferating cell nuclear antigen, NK6 homeobox 1, B cell leukemia/lymphoma 2, but lessening caspase 3. Furthermore, cotadutide mitigated the endoplasmic reticulum (ER) stress-responsive genes, reducing transcription factor 4, DNA-damage-inducible transcript 3, and growth arrest and DNA-damage-inducible 45. In conclusion, our data demonstrated significant beneficial actions of cotadutide in DIO mice, such as weight loss, glycemic control, and insulin resistance improvement. In addition, cotadutide counteracted the pathological adaptive cellular arrangement of the pancreatic islet in obese mice, improving the markers of the transdifferentiating pathway, proliferation, apoptosis, and ER stress.
Asunto(s)
Diabetes Mellitus Tipo 2 , Resistencia a la Insulina , Células Secretoras de Insulina , Islotes Pancreáticos , Masculino , Ratones , Animales , Ratones Obesos , Diabetes Mellitus Tipo 2/metabolismo , Insulina/metabolismo , Ratones Endogámicos C57BL , Islotes Pancreáticos/metabolismo , Células Secretoras de Insulina/metabolismo , Dieta Alta en Grasa/efectos adversos , Pérdida de Peso , ADN/metabolismoRESUMEN
Obesity significantly decreases life expectancy and increases the incidence of age-related dysfunctions, including ß-cell dysregulation leading to inadequate insulin secretion. Here, we show that diluted plasma from obese human donors acutely impairs ß-cell integrity and insulin secretion relative to plasma from lean subjects. Similar results were observed with diluted sera from obese rats fed ad libitum, when compared to sera from lean, calorically restricted, animals. The damaging effects of obese circulating factors on ß-cells occurs in the absence of nutrient overload, and mechanistically involves mitochondrial dysfunction, limiting glucose-supported oxidative phosphorylation and ATP production. We demonstrate that increased levels of adiponectin, as found in lean plasma, are the protective characteristic preserving ß-cell function; indeed, sera from adiponectin knockout mice limits ß-cell metabolic fluxes relative to controls. Furthermore, oxidative phosphorylation and glucose-sensitive insulin secretion, which are completely abrogated in the absence of this hormone, are restored by the presence of adiponectin alone, surprisingly even in the absence of other serological components, for both the insulin-secreting INS1 cell line and primary islets. The addition of adiponectin to cells treated with plasma from obese donors completely restored ß-cell functional integrity, indicating the lack of this hormone was causative of the dysfunction. Overall, our results demonstrate that low circulating adiponectin is a key damaging element for ß-cells, and suggest strong therapeutic potential for the modulation of the adiponectin signaling pathway in the prevention of age-related ß-cell dysfunction.
Asunto(s)
Resistencia a la Insulina , Células Secretoras de Insulina , Ratones , Humanos , Ratas , Animales , Adiponectina/metabolismo , Secreción de Insulina , Insulina/metabolismo , Obesidad/metabolismo , Células Secretoras de Insulina/metabolismo , Glucosa/metabolismo , Resistencia a la Insulina/fisiologíaRESUMEN
Type 1 diabetes (T1D) is characterized by an immune-mediated progressive destruction of the insulin-producing ß-cells. Proinflammatory cytokines trigger endoplasmic reticulum (ER) stress and subsequent insulin secretory deficiency in cultured ß-cells, mimicking the islet microenvironment in T1D. ß-cells undergo physiologic ER stress due to the high rate of insulin production and secretion under stimulated conditions. Severe and uncompensated ER stress in ß-cells is induced by several pathological mechanisms before onset and during T1D. We previously described that the small drug Compound A (CpdA), a selective glucocorticoid receptor (GR/NR3C1, nuclear receptor subfamily 3, group C, member 1) ligand with demonstrated inflammation-suppressive activity in vivo, is an effective modulator of effector T and dendritic cells and of macrophages, yet, in a GR-independent manner. Here, we focus on CpdA's therapeutic potential in T1D cellular and animal models. We demonstrate that CpdA improves the unfolded protein response (UPR) by attenuating ER stress and favoring the survival and function of ß-cells exposed to an environment of proinflammatory cytokines. CpdA administration to NODscid mice adoptively transferred with diabetogenic splenocytes (from diabetic NOD mice) led to a delay of disease onset and reduction of diabetes incidence. Histological analysis of the pancreas showed a reduction in islet leukocyte infiltration (insulitis) and preservation of insulin expression in CpdA-treated normoglycemic mice in comparison with control group. These new findings together with our previous reports justify further studies on the administration of this small molecule as a novel therapeutic strategy with dual targets (effector immune and ß-cells) during autoimmune diabetes.
Asunto(s)
Diabetes Mellitus Tipo 1 , Células Secretoras de Insulina , Ratones , Animales , Ratones Endogámicos NOD , Estrés del Retículo Endoplásmico , Citocinas/metabolismo , Células Secretoras de Insulina/metabolismo , Insulina/metabolismo , Modelos Animales de EnfermedadRESUMEN
Resistance training increases insulin secretion and beta cell function in healthy mice. Here, we explored the effects of resistance training on beta cell glucose sensing and survival by using in vitro and in vivo diabetic models. A pancreatic beta cell line (INS-1E), incubated with serum from trained mice, displayed increased insulin secretion, which could be linked with increased expression of glucose transporter 2 (GLUT2) and glucokinase (GCK). When cells were exposed to pro-inflammatory cytokines (in vitro type 1 diabetes), trained serum preserved both insulin secretion and GCK expression, reduced expression of proteins related to apoptotic pathways, and also protected cells from cytokine-induced apoptosis. Using 8-week-old C57BL/6 mice, turned diabetic by multiple low doses of streptozotocin, we observed that resistance training increased muscle mass and fat deposition, reduced fasting and fed glycemia, and improved glucose tolerance. These findings may be explained by the increased fasting and fed insulinemia, along with increased beta cell mass and beta cell number per islet, observed in diabetic-trained mice compared to diabetic sedentary mice. In conclusion, we believe that resistance training stimulates the release of humoral factors which can turn beta cells more resistant to harmful conditions and improve their response to a glucose stimulus.
Asunto(s)
Diabetes Mellitus , Células Secretoras de Insulina , Condicionamiento Físico Animal , Entrenamiento de Fuerza , Animales , Glucemia/metabolismo , Diabetes Mellitus/metabolismo , Glucoquinasa/metabolismo , Glucosa/metabolismo , Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Ratones , Ratones Endogámicos C57BLRESUMEN
Bile acid tauroursodeoxycholic (TUDCA), formed from the association of ursodeoxycholic acid (UDCA) with taurine, has already been shown to increase mitochondrial biogenesis and cell survival, in addition to reduce reticulum stress markers in different cell types. However, its mechanism of action upon insulin secretion control in obesity is still unknown. In this sense, we seek to clarify whether taurine, associated with bile acid, could improve the function of the pancreatic ß-cells exposed to fatty acids through the regulation of mitochondrial metabolism. To test this idea, insulin-producing cells (INS1-E) were exposed to a fatty acid mix containing 500 µM of each palmitate and oleate for 48 hours treated or not with 300 µM of TUDCA. After that, glucose-stimulated insulin secretion and markers of mitochondrial metabolism were evaluated. Our results showed that the fatty acid mix was efficient in inducing hyperfunction of INS1-E cells as observed by the increase in insulin secretion, protein expression of citrate synthase, and mitochondrial density, without altering cell viability. The treatment with TUDCA normalized insulin secretion, reducing the protein expression of citrate synthase, mitochondrial mass, and the mitochondrial membrane potential. This effect was associated with a decrease in the generation of mitochondrial superoxide and c-Jun N-terminal kinase (JNK) protein content. The findings are also consistent with the hypothesis that TUDCA normalizes insulin secretion by improving mitochondrial metabolism and redox balance. Thus, it highlights likely mechanisms of the action of this bile acid on the glycemic homeostasis reestablishment in obesity.
Asunto(s)
Ácidos y Sales Biliares , Células Secretoras de Insulina , Taurina , Citrato (si)-Sintasa/metabolismo , Ácidos Grasos , Humanos , Insulina/metabolismo , Secreción de Insulina , Células Secretoras de Insulina/metabolismo , Obesidad , Taurina/farmacología , Ácido Tauroquenodesoxicólico/farmacologíaRESUMEN
Cell-to-cell interactions mediated by intercellular junctions (IJs) are crucial for beta-cell functioning and proper insulin secretion, however, their role in type-2 diabetes is still unclear. This work aimed to evaluate the cellular distribution and expression of proteins associated with adherens (AJs) and gap junctions (GJs) in pancreatic islets of C57BL6 mice fed a high-fat (HF) diet. The administration of HF diet for 30 days induced an increase in body weight, post-prandial glycemia, insulinemia, glucose intolerance, and moderate insulin resistance associated with mild perturbations in insulin secretion. The intercellular content of the AJ-associated proteins (namely, E-, N-cadherins, and α-, ß-catenins) was significantly higher in islet cells of HF-fed mice. Inversely, the gap junctional content of Cx36 was significantly decreased, as revealed by immunofluorescence, which was paralleled by a reduction in the frequency of calcium oscillations in islets of prediabetic mice. In conclusion, the endocrine pancreas displays significant changes in the content of several junctional proteins at the cell-cell contact region following short-term HF diet administration, indicating that IJs may be involved in the adaptive response of beta cells seen during this state.
Asunto(s)
Células Secretoras de Insulina , Islotes Pancreáticos , Animales , Moléculas de Adhesión Celular/metabolismo , Dieta Alta en Grasa/efectos adversos , Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Ratones , Ratones Endogámicos C57BLRESUMEN
Metformin is the first-line drug to treat type 2 diabetes mellitus. Its mechanism of action is still debatable, and recent studies report that metformin attenuates oxidative stress. This study evaluated the in vitro antioxidant effects of a broad range of metformin concentrations on insulin-producing cells. The cell cycle, metabolism, glucose-stimulated insulin secretion, and cell death were evaluated to determine the biguanide effects on beta-cell function and survival. Antioxidant potential was based on reactive oxygen species (ROS), reduced glutathione (GSH), oxidative stress biomarker levels, and antioxidant enzyme and transcriptional factor Nrf2 activities. The results demonstrate that metformin disrupted GSIS in a concentration-dependent manner, lowered insulin content, and attenuated beta-cell metabolism. At high concentrations, metformin induced cell death and cell cycle arrest as well as increased ROS generation, consequently reducing GSH content. Although carbonylated protein content was elevated, indicating oxidative stress, the antioxidant enzyme and Nrf2 activities were not altered. In conclusion, our results show that metformin disrupts pancreatic beta-cell functionality but does not exert a putative antioxidant effect. It is important to note that the drug could potentially affect beta-cells, especially at high circulating levels.
Asunto(s)
Diabetes Mellitus Tipo 2 , Células Secretoras de Insulina , Metformina , Animales , Antioxidantes/uso terapéutico , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Insulina/metabolismo , Secreción de Insulina , Células Secretoras de Insulina/metabolismo , Metformina/farmacología , Metformina/uso terapéutico , Factor 2 Relacionado con NF-E2/metabolismo , Estrés Oxidativo , Ratas , Especies Reactivas de Oxígeno/metabolismoRESUMEN
In both type 1 diabetes (T1D) and type 2 diabetes (T2D), there is a substantial ß-cell mass loss. Residual ß-cell mass is susceptible to cellular damage because of specific pancreatic ß-cell characteristics. ß cells have a low proliferation rate, being in human adults almost zero and a low antioxidant system that makes ß cells susceptible to oxidative stress and increases their vulnerability to cell destruction. Different strategies have been addressed to preserve pancreatic ß-cell residual mass and function in patients with diabetes. However, the effect of many compounds proposed in rodent models to trigger ß-cell replication has different results in human ß cells. In this review, scientific evidence of ß-cell of two major regenerative approaches has been gathered. Regeneration proceedings for pancreatic ß cells are promising and could improve ß-cell proliferation capacity and contribute to the conservation of mature ß-cell phenotypic characteristics. This evidence supports the notion that regenerative medicine could be a helpful strategy to yield amelioration of T1D and T2D pathogenesis.
Asunto(s)
Diabetes Mellitus Tipo 1 , Diabetes Mellitus Tipo 2 , Células Secretoras de Insulina , Antioxidantes/metabolismo , Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Humanos , Células Secretoras de Insulina/metabolismo , Estrés OxidativoRESUMEN
Islet amyloid polypeptide (IAPP or amylin) is a hormone co-secreted with insulin by pancreatic ß-cells and is the major component of islet amyloid. Islet amyloid is found in the pancreas of patients with type 2 diabetes (T2D) and may be involved in ß-cell dysfunction and death, observed in this disease. Thus, investigating the aspects related to amyloid formation is relevant to the development of strategies towards ß-cell protection. In this sense, IAPP misprocessing, IAPP overproduction, and disturbances in intra- and extracellular environments seem to be decisive for IAPP to form islet amyloid. Islet amyloid toxicity in ß-cells may be triggered in intra- and/or extracellular sites by membrane damage, endoplasmic reticulum stress, autophagy disruption, mitochondrial dysfunction, inflammation, and apoptosis. Importantly, different approaches have been suggested to prevent islet amyloid cytotoxicity, from inhibition of IAPP aggregation to attenuation of cell death mechanisms. Such approaches have improved ß-cell function and prevented the development of hyperglycemia in animals. Therefore, counteracting islet amyloid may be a promising therapy for T2D treatment.
Asunto(s)
Diabetes Mellitus Tipo 2 , Células Secretoras de Insulina , Islotes Pancreáticos , Amiloide/metabolismo , Animales , Diabetes Mellitus Tipo 2/metabolismo , Humanos , Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Polipéptido Amiloide de los Islotes Pancreáticos/genética , Polipéptido Amiloide de los Islotes Pancreáticos/metabolismo , Islotes Pancreáticos/metabolismoRESUMEN
Vitamin D3 is associated with improvements in insulin resistance and glycemia. In this study, we investigated the short-term effect of 1α,25(OH)2 Vitamin D3 (1,25-D3) and cholecalciferol (vitamin D3) on the glycemia and insulin sensitivity of control and dexamethasone-induced insulin-resistance rats. 45Ca2+ influx responses to 1,25-D3 and its role in insulin secretion were investigated in isolated pancreatic islets from control rats. In vivo, 5 d treatment with 1,25-D3 (i.p.) prevented insulin resistance in dexamethasone-treated rats. Treatment with 1,25-D3 improved the activities of hepatic enzymes, serum lipids and calcium concentrations in insulin-resistant rats. 25-D3 (o.g.) does not affect insulin resistance. In pancreatic islets, 1,25-D3 increased insulin secretion and stimulated rapid response 45Ca2+ influx. The stimulatory effect of 1,25-D3 on 45Ca2+ influx was decreased by diazoxide, apamine, thapsigargin, dantrolene, 2-APB, nifedipine, TEA, PKA, PKC, and cytoskeleton inhibitor, while it was increased by glibenclamide and N-ethylmaleimide. The stimulatory effect of 1,25-D3 on 45Ca2+ influx involves the activation of L-type VDCC, K+-ATP, K+-Ca2+, and Kv channels, which augment cytosolic calcium. These ionic changes mobilize calcium from stores and downstream activation of PKC, PKA tethering vesicle traffic and fusion at the plasma membrane for insulin secretion. This is the first study highlighting the unprecedented role of 1,25-D3 (short-term effect) in the regulation of glucose homeostasis and on prevention of insulin resistance. Furthermore, this study shows the intracellular ß-cell signal transduction of 1,25-D3 through the modulation of pivotal ionic channels and proteins exhibiting a coordinated exocytosis of vesicles for insulin secretion.