RESUMEN

Long non-coding RNAs (LncRNAs) play important regulatory roles in oxidative damage. Resveratrol, curcumin, and cyanidin are phytogenic antioxidants widely existing in nature and they have been proved to antagonize certain heavy metal-induced oxidative damage in cells. However, can they antagonize oxidative damage induced by cadmium in islet ß cells? Are their mechanisms of antagonizing oxidative damage related to LncRNAs? In this study, we first detected the cell viability of each group by CCK8 assay. Next, reactive oxygen species (ROS) were detected by the fluorescent probe. The contents of malondialdehyde (MDA) and the activities of superoxide dismutase (SOD) were detected according to the instructions of corresponding kits. At last, the levels of LncRNAs were detected by fluorescence quantitative real-time polymerase chain reaction (qPCR). The results showed that resveratrol, curcumin and cyanidin were able to reverse the reduction of cell viability induced by cadmium (CdSO4). Further determination revealed that SOD activities of the resveratrol+CdSO4, curcumin+CdSO4, and cyanidin+CdSO4 treatment groups increased significantly, and ROS levels and MDA contents dramatically decreased when compared with single CdSO4-treated group. More importantly, the levels of three CdSO4-elevated LncRNAs (NONMMUT029382, ENSMUST00000162103, ENSMUST00000117235) were all decreased and levels of three CdSO4-inhibited LncRNAs (NONMMUT036805, NONMMUT014565, NONMMUT065427) were increased after the pretreatment of resveratrol, curcumin and cyanidin. In summary, resveratrol, curcumin and cyanidin may effectly reverse the cadmium-induced oxidative damage and suggest that phytogenic antioxidants may prevent cells from cadmium-induced oxidative damage through changing the levels of LncRNAs.

Asunto(s)

Antocianinas , Antioxidantes , Cadmio , Supervivencia Celular , Curcumina , Células Secretoras de Insulina , Malondialdehído , Estrés Oxidativo , ARN Largo no Codificante , Especies Reactivas de Oxígeno , Resveratrol , Superóxido Dismutasa , ARN Largo no Codificante/metabolismo , ARN Largo no Codificante/genética , Antioxidantes/farmacología , Estrés Oxidativo/efectos de los fármacos , Resveratrol/farmacología , Supervivencia Celular/efectos de los fármacos , Cadmio/toxicidad , Superóxido Dismutasa/metabolismo , Malondialdehído/metabolismo , Curcumina/farmacología , Especies Reactivas de Oxígeno/metabolismo , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/citología , Antocianinas/farmacología , Animales , Línea Celular

RESUMEN

Differentiation of human umbilical cord mesenchymal stem cells (Uc-MSCs) into islet-like clusters which are capable of synthesizing and secreting insulin can potentially serve as donors for islet transplantation in the patient deficiency in islet ß cell function both in type 1 or type 2 diabetic patients. Therefore, we developed an easy and higher efficacy approach by trypsinazing the Uc-MSCs and followed culture in differentiation medium to induce of Uc-MSCs differentiation into islet-like clusters, and the potential mechanism that in the early stage of differentiation was also investigated by using RNA-sequencing and bioinformatics. Results show that induction efficacy was reached to 98% and TGF-ß signaling pathway may play critical role in the early stage differentiation, it was further confirmed that the retardant effect of differentiation progress either in cell morphology or in islet specific genes expression can be observed upon blocking the activation of TGF-ß signaling pathway using specific inhibitor of LY2109761 (TßRI/II kinase inhibitor). Our current study, for the first time, development a protocol for differentiation of Uc-MSCs into islet-like clusters, and revealed the importance of TGF-ß signaling pathway in the early stage of differentiation of Uc-MSCs into islet-like clusters. Our study will provide alternative approach for clinical treatment of either type I or type II diabtes mellitus with dysfunctional pancreatic islets.

Asunto(s)

Células Secretoras de Insulina , Células Madre Mesenquimatosas , Humanos , Insulina , Tripsina/metabolismo , Diferenciación Celular/genética , Factor de Crecimiento Transformador beta/genética , Factor de Crecimiento Transformador beta/metabolismo , Transducción de Señal , Cordón Umbilical

RESUMEN

OBJECTIVE: Islet α cells input is essential for insulin secretion from ß cells. The present study aims to investigate the association between 25-hydroxyvitamin D [25(OH)D] and islet function homeostasis in type-2 diabetes (T2D) patients. METHODS: A total of 4670 T2D patients from seven communities in Shanghai, China were enrolled. The anthropometric indices, biochemical parameters, serum 25(OH)D, and islet function [including C-peptide (C-p) and glucagon] were measured. RESULTS: The fasting plasma glucose (FPG), glycated hemoglobin (HbA1c), glucagon, and C-p levels exhibited a significantly decreasing trend in T2D patients as the 25(OH)D levels increased. Next, the population was divided into two groups: abdominal obesity and non-abdominal obesity groups. After adjustment, the 25(OH)D level was found to be associated with HbA1c, glucagon, and homeostasis model assessment of ß (HOMA-ß) in the non-abdominal obesity group. There was a significant relationship between 25(OH)D and HbA1c, glucagon, HOMA-IR, baseline insulin or C-p in the abdominal obesity group. In the abdominal obesity group, the ordinary least squares (OLS) regression and quantile regression revealed that 25(OH) D was obviously associated with glucagon and fasting C-p levels. In the abdominal obesity group, the moderate analysis revealed a significant interaction effect of 25(OH)D and glucagon on C-p (P=0.0124). Furthermore, the conditional indirect effect of 25(OH)D on the glucagon/C-p ratio was significantly lower at 1 standard deviation (SD) below the mean (P=0.0002), and lower at the mean of the course of diabetes (P=0.0007). CONCLUSION: 25(OH)D was found to be negatively correlated to glucagon and C-p in T2D patients with abdominal obesity. The 25(OH)D influenced C-p in part by influencing glucagon. The effect of 25(OH)D on the glucagon/C-p ratio in T2D patients with abdominal obesity, in terms of islet homeostasis, is influenced by the course of diabetes.

RESUMEN

A century has passed since the Nobel Prize winning discovery of insulin, which still remains the mainstay treatment for type 1 diabetes mellitus (T1DM) to this day. True to the words of its discoverer Sir Frederick Banting, "insulin is not a cure for diabetes, it is a treatment", millions of people with T1DM are dependent on daily insulin medications for life. Clinical donor islet transplantation has proven that T1DM is curable, however due to profound shortages of donor islets, it is not a mainstream treatment option for T1DM. Human pluripotent stem cell derived insulin-secreting cells, pervasively known as stem cell-derived ß cells (SC-ß cells), are a promising alternative source and have the potential to become a T1DM treatment through cell replacement therapy. Here we briefly review how islet ß cells develop and mature in vivo and several types of reported SC-ß cells produced using different ex vivo protocols in the last decade. Although some markers of maturation were expressed and glucose stimulated insulin secretion was shown, the SC-ß cells have not been directly compared to their in vivo counterparts, generally have limited glucose response, and are not yet fully matured. Due to the presence of extra-pancreatic insulin-expressing cells, and ethical and technological issues, further clarification of the true nature of these SC-ß cells is required.

RESUMEN

N6-methyladenosine (m6A) methyltransferase writer proteins (METTL3/METTL14) have been shown to regulate ß-cell function and diabetes. However, whether and which m6A reader proteins regulate ß-cell function and the pathogenesis of diabetes are largely unknown. In this study, we showed that YTHDC1 (YTH domain-containing protein 1), a key m6A nuclear reader protein, plays an essential role in maintaining ß-cell function. YTHDC1 is downregulated in islet ß cells in type 2 diabetes, which is due to lipotoxicity and chronic inflammation. ß-Cell specific deletion of Ythdc1 results in ß-cell failure and diabetes, which is likely due to the decreased expression of ß-cell specific transcription factors and insulin secretion-related genes. Taken together, YTHDC1 is required for maintaining ß-cell function, and the downregulation of YTHDC1 leads to ß-cell failure and diabetes.

Asunto(s)

Diabetes Mellitus Tipo 2 , Humanos , Factores de Empalme de ARN/genética , Factores de Empalme de ARN/metabolismo , Regulación hacia Abajo , Proteínas del Tejido Nervioso/genética , Adenosina/metabolismo , Proteínas Nucleares/metabolismo , Metiltransferasas/genética

RESUMEN

Type 1 diabetes (T1D) is a condition characterized by an absolute deficiency of insulin. Loss of insulin-producing pancreatic islet ß cells is one of the many causes of T1D. Viral infections have long been associated with new-onset T1D and the balance between virulence and host immunity determines whether the viral infection would lead to T1D. Herein, we detail the dynamic interaction of pancreatic ß cells with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the host immune system with respect to new-onset T1D. Importantly, ß cells express the crucial entry receptors and multiple studies confirmed that ß cells are infected by SARS-CoV-2. Innate immune system effectors, such as natural killer cells, can eliminate such infected ß cells. Although CD4+ CD25+ FoxP3+ regulatory T (TREG ) cells provide immune tolerance to prevent the destruction of the islet ß-cell population by autoantigen-specific CD8+ T cells, it can be speculated that SARS-CoV-2 infection may compromise self-tolerance by depleting TREG -cell numbers or diminishing TREG -cell functions by repressing Forkhead box P3 (FoxP3) expression. However, the expansion of ß cells by self-duplication, and regeneration from progenitor cells, could effectively replace lost ß cells. Appearance of islet autoantibodies following SARS-CoV-2 infection was reported in a few cases, which could imply a breakdown of immune tolerance in the pancreatic islets. However, many of the cases with newly diagnosed autoimmune response following SARS-CoV-2 infection also presented with significantly high HbA1c (glycated hemoglobin) levels that indicated progression of an already set diabetes, rather than new-onset T1D. Here we review the potential underlying mechanisms behind loss of functional ß-cell mass as a result of SARS-CoV-2 infection that can trigger new-onset T1D.

Asunto(s)

COVID-19 , Diabetes Mellitus Tipo 1 , Virosis , Humanos , Linfocitos T CD8-positivos/metabolismo , Linfocitos T Reguladores , SARS-CoV-2/metabolismo , Insulina/metabolismo , Factores de Transcripción Forkhead/metabolismo

RESUMEN

Vitamin B6 may alleviate diabetes by regulating insulin secretion and increasing insulin sensitivity, but its mechanism remains to be explored. In this study, vitamin B6-mediated autophagy and high glucose-induced apoptosis were tested to investigate the mechanism by which vitamin B6 regulates insulin release. The results showed that 20 mM glucose increased the apoptosis rate from 10.39% to 22.44%. Vitamin B6 reduced the apoptosis rate of RIN-m5F cells from 22.44% to 11.31%. Our data also showed that the vitamin B6 content in processed eggs was decreased and that the hydrothermal process did not affect the bioactivity of vitamin B6. Vitamin B6 increased the number of autophagosomes and the ratio of autophagosome marker protein microtubule associated protein 1 light chain 3 beta to microtubule associated protein 1 light chain 3 alpha (LC3-II/LC3-I). It also decreased the amount of sequetosome 1 (SQSTM1/p62) and inhibited the phosphorylation of p70 ribosomal protein S6 kinase (p70S6K) under normal and high glucose stress. Another study showed that vitamin B6 inhibited the apoptosis rate, whereas the autophagy inhibitor 3-methyladenine (3-MA) blocked the protective effect of vitamin B6 against apoptosis induced by high glucose. The hydrothermal process decreased the vitamin B6 content in eggs but had no effect on the cytoprotective function of vitamin B6 in RIN-m5f cells. In conclusion, we demonstrated that vitamin B6-mediated autophagy protected RIN-m5f cells from high glucose-induced apoptosis might via the mTOR-dependent pathway. Our data also suggest that low temperatures and short-term hydrothermal processes are beneficial for dietary eggs.

RESUMEN

Type 1 diabetes (T1D) is an autoimmune disease resulted from the unrestrained inflammatory attack towards the insulin-producing islet ß cells. Although the exact etiology underlying T1D remains elusive, viral infections, especially those specific strains of enterovirus, are acknowledged as a critical environmental cue involved in the early phase of disease initiation. Viral infections could either directly impede ß cell function, or elicit pathological autoinflammatory reactions for ß cell killing. Autoimmune responses are bolstered by a massive body of virus-derived exogenous pathogen-associated molecular patterns (PAMPs) and the presence of ß cell-derived damage-associated molecular patterns (DAMPs). In particular, the nucleic acid components and the downstream nucleic acid sensing pathways serve as the major effector mechanism. The endogenous retroviral RNA, mitochondrial DNA (mtDNA) and genomic fragments generated by stressed or dying ß cells induce host responses reminiscent of viral infection, a phenomenon termed as viral mimicry during the early stage of T1D development. Given that the interferon regulatory factors (IRFs) are considered as hub transcription factors to modulate immune responses relevant to viral infection, we thus sought to summarize the critical role of IRFs in T1D pathogenesis. We discuss with focus for the impact of IRFs on the sensitivity of ß cells to cytokine stimulation, the vulnerability of ß cells to viral infection/mimicry, and the intensity of immune response. Together, targeting certain IRF members, alone or together with other therapeutics, could be a promising strategy against T1D.

Asunto(s)

Diabetes Mellitus Tipo 1 , Infecciones por Enterovirus , Ácidos Nucleicos , Virosis , Diabetes Mellitus Tipo 1/patología , Humanos , Factores Reguladores del Interferón/genética , Moléculas de Patrón Molecular Asociado a Patógenos

RESUMEN

Background: Morus alba L. (Sangzhi) alkaloids (SZ-A), extracted from the Chinese herb Morus alba L. (mulberry twig), have been shown to ameliorate hyperglycemia in type 2 diabetes and have been approved for diabetes treatment in the clinic. However, their versatile pharmacologic effects and regulatory mechanisms are not yet completely understood. Purpose: This study explored the protective effects of SZ-A on islet ß cells and the underlying mechanism. Methods: Type 2 diabetic KKAy mice were orally administered SZ-A (100 or 200 mg/kg, once daily) for 11 weeks, and oral glucose tolerance, insulin tolerance, intraperitoneal glucose tolerance and hyperglycemia clamp tests were carried out to evaluate the potency of SZ-A in vivo. The morphology and ß-cell dedifferentiation marker of KKAy mouse islets were detected via immunofluorescence. The effect of SZ-A on glucose-stimulated insulin secretion was investigated in both the islet ß-cell line MIN6 and mouse primary islets. Potential regulatory signals and pathways in insulin secretion were explored, and cell proliferation assays and apoptosis TUNEL staining were performed on SZ-A-treated MIN6 cells. Results: SZ-A alleviated hyperglycemia and glucose intolerance in type 2 diabetic KKAy mice and improved the function and morphology of diabetic islets. In both MIN6 cells and primary islets, SZ-A promoted insulin secretion. At a normal glucose level, SZ-A decreased AMPKα phosphorylation, and at high glucose, SZ-A augmented the cytosolic calcium concentration. Additionally, SZ-A downregulated the ß-cell dedifferentiation marker ALDH1A3 and upregulated ß-cell identifying genes, such as Ins1, Ins2, Nkx2.2 and Pax4 in KKAy mice islets. At the same time, SZ-A attenuated glucolipotoxicity-induced apoptosis in MIN6 cells, and inhibited Erk1/2 phosphorylation and caspase 3 activity. The major active fractions of SZ-A, namely DNJ, FAG and DAB, participated in the above regulatory effects. Conclusion: Our findings suggest that SZ-A promotes insulin secretion in islet ß cells and ameliorates ß-cell dysfunction and mass reduction under diabetic conditions both in vivo and in vitro, providing additional supportive evidence for the clinical application of SZ-A.

RESUMEN

Type 1 diabetes (T1D) is a T cell-mediated autoimmune disease. Increased incidence of T1D was reported in patients receiving IFN-α treatment. However, the exact mechanisms of IFN-α that facilitate the pathogenesis of T1D are not fully understood. To explore the mechanism of IFN-α on the immune system and islets, non-obese diabetic (NOD) mice were injected with IFN-α and the progression of autoimmune insulitis was assessed by haematoxylin and eosin (HE) staining, immunohistochemical and flow cytometry analysis. Transcriptional profiling of islets treated with IFN-α was explored by RNA-seq. IFN-α induced antigen presentation was evaluated by qRT-PCR, western blot and immunofluorescence, and key transcription factors were inhibited by small interfering RNAs (siRNAs). Our data show that IFN-α contributed to the progression of autoimmune insulitis in NOD mice by promoting the proliferation of CD8+ T cells. IFN-α upregulated antigen presentation related genes MHC I, TAP1, B2M, PSMB8, NLRC5 and transcriptional regulator STAT1, STAT2, IRF7 at a time and dose-dependent manner. The silence of STAT1 or STAT2 both weakened IFN-α-induced increase of antigen presenting related molecules. IRF7 was also merely influenced by STAT1 silence. The knockdown of IRF7 decreased the IFN-α induced expressions of TAP1, PSMB8 and MHC I and prevented the expression of STAT2 but not STAT1. Our study demonstrated that STAT1-IRF7-MHC I complex axis were crucial for IFN-α signalling in islets, and created positive feedback through IRF7-STAT2 cascade amplifying signals which accelerated the process of T1D.

Asunto(s)

Presentación de Antígeno , Diabetes Mellitus Tipo 1 , Interferón-alfa , Islotes Pancreáticos , Animales , Antígenos de Histocompatibilidad Clase I/metabolismo , Humanos , Factor 7 Regulador del Interferón/genética , Factor 7 Regulador del Interferón/metabolismo , Interferón-alfa/farmacología , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Ratones , Ratones Endogámicos NOD , Factor de Transcripción STAT1/genética , Factor de Transcripción STAT1/metabolismo

RESUMEN

Islet ß cell dedifferentiation is one of the most important mechanisms in the occurrence and development of diabetes. We studied the possible effects of chemokine stromal cell-derived factor-1 (SDF-1) in the dedifferentiation of islet ß cells. It was noted that the number of dedifferentiated islet ß cells and the expression of SDF-1 in pancreatic tissues significantly increased with diabetes. In islet ß cell experiments, inhibition of SDF-1 expression resulted in an increase in the number of dedifferentiated cells, while overexpression of SDF-1 resulted in a decrease. This seemed to be contradicted by the effect of diabetes on the expression of SDF-1 in pancreatic tissue, but it was concluded that this may be related to the loss of SDF-1 activity. SDF-1 binds to CXCR4 to form a complex, which activates and phosphorylates AKT, subsequently increases the expression of forkhead box O1 (FOXO1), and inhibits the dedifferentiation of islet ß cells. This suggests that SDF-1 may be a novel target in the treatment of diabetes.

Asunto(s)

Hiperglucemia , Células Secretoras de Insulina , Islotes Pancreáticos , Quimiocina CXCL12/metabolismo , Proteína Forkhead Box O1/genética , Proteína Forkhead Box O1/metabolismo , Humanos , Hiperglucemia/metabolismo , Células Secretoras de Insulina/metabolismo , Islotes Pancreáticos/metabolismo , Páncreas/metabolismo , Receptores CXCR4/genética , Receptores CXCR4/metabolismo , Transducción de Señal

RESUMEN

The regulation of glucose-stimulated insulin secretion and glucose excursion has a sensory component that operates in a sex-dependent manner. OBJECTIVE: Here, we aim to dissect the basis of the sexually dimorphic interaction between sensory neurons and pancreatic ß cells and its overall impact on insulin release and glucose homeostasis. METHODS: We used viral retrograde tracing techniques, surgical and chemodenervation models, and primary cell-based co-culture systems to uncover the biology underlying sex differences in sensory modulation of pancreatic ß-cell activity. RESULTS: Retrograde transsynaptic labeling revealed a sex difference in the density of sensory innervation in the pancreas. The number of sensory neurons emanating from the dorsal root and nodose ganglia that project in the pancreas is higher in male than in female mice. Immunostaining and confocal laser scanning microscopy confirmed the higher abundance of peri-islet sensory axonal tracts in the male pancreas. Capsaicin-induced sensory chemodenervation concomitantly enhanced glucose-stimulated insulin secretion and glucose clearance in male mice. These metabolic benefits were blunted when mice were orchidectomized prior to the ablation of sensory nerves. Interestingly, orchidectomy also lowered the density of peri-islet sensory neurons. In female mice, capsaicin treatment did not affect glucose-induced insulin secretion nor glucose excursion and ovariectomy did not modify these outcomes. Interestingly, same- and opposite-sex sensory-islet co-culture paradigms unmasked the existence of potential gonadal hormone-independent mechanisms mediating the male-female difference in sensory modulation of islet ß-cell activity. CONCLUSION: Taken together, these data suggest that the sex-biased nature of the sensory control of islet ß-cell activity is a result of a combination of neurodevelopmental inputs, sex hormone-dependent mechanisms and the potential action of somatic molecules encoded by the sex chromosome complement.

Asunto(s)

Células Secretoras de Insulina/metabolismo , Células Receptoras Sensoriales/metabolismo , Animales , Glucemia/metabolismo , Femenino , Homeostasis , Secreción de Insulina , Masculino , Ratones , Ratones Endogámicos C57BL , Caracteres Sexuales

RESUMEN

Various subtypes of protein kinase C (PKC) are expressed in islet ß cells and regulate ß cell proliferation and survival. PKC-θ is distributed in the immune system and promotes the secretion of IL-10, which manifests a critical role in the onset of diabetes, by the immune cells. However, the role of PKC-θ in islets has not been concerned. In the present study, we investigated the role of PKC-θ in the protection of islet ß cells and insulin secretion. Fasting glucose and insulin measurement, glucose tolerant test, immunofluorescence, and ELISA were conducted to study the influence of PKC-θ knockout on islet ß cell survival and function, and explore the mechanism underlying this regulation. PKC-θ knockout mice at 2 weeks manifested normal serum insulin levels, glucose tolerance, and ß cell mass. Knockout mice at 8 weeks show decreased ß cell mass, but manifested normal insulin levels and glucose tolerance. Knockout mice at 16 weeks manifested impaired glucose tolerance, ß cell mass, and decreased glucose stimulated insulin secretion. Furthermore, knockout mice manifested decreased serum IL-10 level compared with normal mice since 2 weeks. IL-10 injection into knockout mice improved glucose tolerance, serum insulin level, and reduced ß cell mass, and IL-10 administration into cultured pancreatic tissue increased glucose stimulated insulin secretion. PKC-θ knockout decreases the secretion of IL-10, reduces ß cell mass and insulin secretion in pancreatic islets. The present study illuminates the critical role of PKC-θ in protecting the survival and function of islet ß cells.

Asunto(s)

Células Secretoras de Insulina , Interleucina-10/sangre , Islotes Pancreáticos , Proteína Quinasa C-theta/genética , Animales , Glucosa/metabolismo , Insulina/metabolismo , Secreción de Insulina , Células Secretoras de Insulina/metabolismo , Islotes Pancreáticos/metabolismo , Ratones , Ratones Noqueados

RESUMEN

N6-methyladenosine (m6A) mRNA methylation has been shown to regulate obesity and type 2 diabetes. However, whether METTL3, the key methyltransferase for m6A mRNA methylation, regulates ß-cell failure in diabetes has not been fully explored. Here, we show that METTL3 is downregulated under the inflammatory and oxidative stress conditions, and islet ß-cell-specific deletion of Mettl3 induces ß-cell failure and hyperglycemia, which is likely due to decreased m6A modification and reduced expression of insulin secretion-related genes. Overall, METTL3 might be a potential drug target for the treatment of ß-cell failure in diabetes.

Asunto(s)

Diabetes Mellitus/genética , Células Secretoras de Insulina/fisiología , Metiltransferasas/fisiología , Animales , Diabetes Mellitus/patología , Diabetes Mellitus/fisiopatología , Islotes Pancreáticos/fisiología , Islotes Pancreáticos/fisiopatología , Metiltransferasas/genética , Ratones , Ratones Noqueados , Enfermedades Pancreáticas/genética , Enfermedades Pancreáticas/patología , Enfermedades Pancreáticas/fisiopatología

RESUMEN

Metabolic fuels regulate insulin secretion by generating second messengers that drive insulin granule exocytosis, but the biochemical pathways involved are incompletely understood. Here we demonstrate that stimulation of rat insulinoma cells or primary rat islets with glucose or glutamine + 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (Gln + BCH) induces reductive, "counter-clockwise" tricarboxylic acid (TCA) cycle flux of glutamine to citrate. Molecular or pharmacologic suppression of isocitrate dehydrogenase-2 (IDH2), which catalyzes reductive carboxylation of 2-ketoglutarate to isocitrate, results in impairment of glucose- and Gln + BCH-stimulated reductive TCA cycle flux, lowering of NADPH levels, and inhibition of insulin secretion. Pharmacologic suppression of IDH2 also inhibits insulin secretion in living mice. Reductive TCA cycle flux has been proposed as a mechanism for generation of biomass in cancer cells. Here we demonstrate that reductive TCA cycle flux also produces stimulus-secretion coupling factors that regulate insulin secretion, including in non-dividing cells.

Asunto(s)

Ciclo del Ácido Cítrico/fisiología , Glucosa/farmacología , Glutamina/farmacología , Secreción de Insulina/efectos de los fármacos , Animales , Células Cultivadas , Glucosa/metabolismo , Glutamina/metabolismo , Islotes Pancreáticos/citología , Islotes Pancreáticos/metabolismo , Isocitrato Deshidrogenasa/antagonistas & inhibidores , Isocitrato Deshidrogenasa/genética , Isocitrato Deshidrogenasa/metabolismo , Lipogénesis/efectos de los fármacos , Masculino , Ratones , Ratones Endogámicos C57BL , Oxidación-Reducción , Compuestos de Fenilurea/farmacología , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Interferencia de ARN , ARN Interferente Pequeño/metabolismo , Ratas , Ratas Wistar , Sulfonamidas/farmacología , Sumoilación/efectos de los fármacos

RESUMEN

The study focused on the toxicological effect of Di-n-butyl phthalate (DBP) on the expression of Phosphorylated signal transducer and activator of transcription 1 (pSTAT1) -regulated Forkhead box protein M1 (FoxM1), which might provide a new understanding of gestational diabetes mellitus (GDM) development and a potential target for treatment. Streptozotocin (STZ) (40 mg/kg) was introduced in maternal rats by intraperitoneal injection on gestation day 0 (GD 0) in the STZ and STZ + DBP groups. DBP was introduced in maternal rats by oral feeding in the STZ + DBP group over the following 3 days (750 mg/kg/day). The changes in fasting blood glucose level in rats were detected on GD 1 and GD 5. The insulin levels in maternal rats and PIBCs were measured on GD 18. The Oral Glucose Tolerance Test (OGTT) test was performed on GD 18 to check the stability of the GDM model. The primary islet ß cells (PIBCs) were established for in vitro experiments. We examined the FoxM1 and pSTAT1 expression in pancreas by immunohistochemistry. Real-time PCR and Western blot were used to detect the pSTAR1 and FoxM1 protein and mRNA gene expression levels in PIBCs. Cell Counting Kit-8 (CCK-8) and flow cytometric analysis was used to test the viability and apoptosis of cells. The results showed that the STZ + DBP group had higher glucose and lower insulin secretion levels than the other groups by both fasting test and OGTT. FoxM1 was significantly suppressed while pSTAT1 was highly expressed after DBP exposure. FoxM1 could be regulated by pSTAT1. DBP can influence the progression of GDM through its toxicological effect, which significantly increases the expression of pSTAT1 and suppresses FoxM1, causing a decline in ß cell viability.

Asunto(s)

Diabetes Mellitus Experimental/inducido químicamente , Diabetes Gestacional/inducido químicamente , Dibutil Ftalato/toxicidad , Disruptores Endocrinos/toxicidad , Proteína Forkhead Box M1/metabolismo , Exposición Materna/efectos adversos , Factor de Transcripción STAT1/metabolismo , Animales , Células Cultivadas , Diabetes Mellitus Experimental/metabolismo , Diabetes Gestacional/metabolismo , Femenino , Proteína Forkhead Box M1/genética , Expresión Génica/efectos de los fármacos , Humanos , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/metabolismo , Masculino , Fosforilación , Embarazo , Cultivo Primario de Células , Ratas , Ratas Sprague-Dawley , Factor de Transcripción STAT1/genética , Transducción de Señal

RESUMEN

Islet ß cell death has been proved to contribute to diabetes. Studies suggest that the activation of nuclear factor κB (NF-κB)-inducing kinase (NIK) is involved in the ß cell dysfunction encountered in obesity. However, the pathological significance of NIK activation in diabetes remains largely unknown. Here, we report that ß cell-specific overexpression of NIK (ß-NIK-OE) results in spontaneous diabetes in male mice at a young age (≥10 weeks of age), which is likely due to insulin deficiency, ß cell death, and insulitis. Importantly, inhibiting the kinase activation of NIK by the small molecule B022 prevents NIK- or H2O2-induced ß cell death and also reduces streptozotocin (STZ)-induced ß cell death while ameliorating hyperglycemia, suggesting that the kinase activity of NIK is essential in inducing islet inflammation, ß cell death, and diabetes. In all, this study not only uncovers a role of NIK in ß cell failure but also provides a potential therapeutic target for the treatment of diabetes.

Asunto(s)

Diabetes Mellitus/etiología , Diabetes Mellitus/metabolismo , Células Secretoras de Insulina/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Animales , Muerte Celular , Modelos Animales de Enfermedad , Peróxido de Hidrógeno/metabolismo , Peróxido de Hidrógeno/farmacología , Insulina/metabolismo , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/patología , Masculino , Ratones , FN-kappa B/metabolismo , Sustancias Protectoras/farmacología , Transducción de Señal , Estreptozocina/efectos adversos , Quinasa de Factor Nuclear kappa B

RESUMEN

Gestational diabetes mellitus (GDM) refers to glucose intolerance of variable degree with onset or first recognition during pregnancy. It causes polyhydramnios, ketoacidosis, fetal macrosomia, and neonatal respiratory distress syndrome. The incidence of GDM has greatly increased, hence the search for new interventions that can effectively treat it. The present study investigated the protective effect of ferulic acid on islet ß cells and placental tissues of rats with GDM. Female Sprague Dawley rats (n = 30) were used in this study. The rats were randomly assigned to three groups of 10 rats each: control group, GDM group and ferulic acid group. The rats were fed high-fat diet consecutively for 12 weeks, except those in control group. In addition, ferulic acid group rats received ferulic acid at a dose of 20 mg/kg body weight (bwt) intragastrically daily for 12 weeks. The expressions of insulin signal transduction proteins and inflammatory factors were determined in rat placental tissue. Apoptosis and levels of expression of apoptosis-related proteins were assessed in isolated islet ß cells. The results showed that the expressions of p-IRS1, p-IRS2, p-PI3K, GLUT1, GLUT3, and GLUT4 were significantly reduced by GDM, but were significantly upregulated after treatment with ferulic acid (p < 0.05). The levels of expression of NF-kB, ICAM-1, TNF-α and IL-ß in placental tissues were significantly higher in GDM group than in control group, but were significantly reduced by ferulic acid treatment (p < 0.05). However, the protein expression of visfatin was significantly reduced by GDM, but was significantly increased by ferulic acid treatment (p < 0.05). Apoptosis was significantly promoted by GDM in islet ß cells, but was significantly and concentration-dependently reduced after treatment with ferulic acid (p < 0.05). Gestational diabetes mellitus (GDM) also significantly down-regulated the expression of bcl-2, but markedly upregulated the expressions of bax and caspase-3 (p < 0.05). However, treatment with ferulic acid significantly and concentration-dependently upregulated the expression of bcl-2, but down-regulated bax and caspase-3 protein expressions (p < 0.05). These results indicate that ferulic acid protects ß cells from GDM-induced apoptosis and improves insulin signaling in placenta of female rats with GDM.

Asunto(s)

Ácidos Cumáricos/farmacología , Citoprotección/efectos de los fármacos , Diabetes Gestacional/patología , Células Secretoras de Insulina/patología , Placenta/patología , Sustancias Protectoras/farmacología , Animales , Apoptosis/efectos de los fármacos , Proteínas Reguladoras de la Apoptosis/metabolismo , Ácidos Cumáricos/química , Femenino , Mediadores de Inflamación/metabolismo , Insulina/metabolismo , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/metabolismo , Placenta/efectos de los fármacos , Placenta/metabolismo , Embarazo , Ratas Sprague-Dawley , Transducción de Señal

RESUMEN

AIMS: Type 1 diabetes (T1D) is the most common autoimmune disease that affects a global scale. Accumulating evidence has indicated, nuclear factor kappa B (NF-κB) and some microRNAs (miRNAs) as important biomarkers participating in the development of T1D. Thus, we aimed to determine the role of NF-κB and miR-150 in the development of T1D and to unravel the molecular mechanism. MAIN METHODS: Non-obese diabetic mice were used for the T1D model establishment by injecting with streptozotocin. Besides, pancreatic islet ß cells, separated from T1D mice, were induced by interferon-γ and tumor necrosis factor-α for 3 days to mimic T1D damage. The expression of NF-κB p65, miR-150, and p53 up-regulated modulator of apoptosis (PUMA) was evaluated by RT-qPCR, while the expression of PUMA, p65, and apoptotic proteins in pancreatic islet ß cells were determined by western blot analysis. Besides, inflammatory factors IL-17A, IL-2, IFN-γ, and IL-4 were detected by ELISA. The relationship among NF-κB, miR-150, and PUMA was analyzed by the dual-luciferase reporter gene, chromatin- and RNA-immunoprecipitation assays, respectively. KEY FINDINGS: Restoration of NF-κB reduced the incidence of T1D in mice. Over-expressed NF-κB inhibited the release of inflammatory factors and apoptosis in pancreatic islet ß cells. PUMA was confirmed to be a potential target gene of miR-150. miR-150 suppressed PUMA to inhibit the T1D-induced inflammation and ß cell apoptosis whereas NF-κB activated the miR-150 expression by binding to the miR-150 promoter, thereby preventing the T1D-induced inflammation and ß cell apoptosis. SIGNIFICANCE: NF-κB/miR-150/PUMA may serve as potential therapeutic targets for T1D.

Asunto(s)

Proteínas Reguladoras de la Apoptosis/genética , Diabetes Mellitus Experimental/fisiopatología , Diabetes Mellitus Tipo 1/fisiopatología , MicroARNs/genética , FN-kappa B/genética , Proteínas Supresoras de Tumor/genética , Animales , Apoptosis/genética , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Tipo 1/genética , Inflamación/genética , Inflamación/patología , Células Secretoras de Insulina/patología , Ratones , Ratones Endogámicos NOD , Regulación hacia Arriba

RESUMEN

Cigarette smoking is a well-recognized risk factor for type 2 diabetes (T2DM), and may result in islet ß cell damage and impaired insulin secretion. However, the underlying mechanisms remain largely elusive. In the present study, we demonstrated that nicotine induced premature senescence of pancreatic ß cells in vitro and in vivo. The senescence-associated ß-galactosidase (SA-ß-Gal) assay showed that nicotine exposure induced apparent senescence phenotype of ß-TC-6 cells at an initiating dose of 100 µM and starting from 12 h. In addition, 100 and 500 µM of nicotine exposure altered the expression of senescence marker proteins, such as p16, p19 and p21. Furthermore, we uncovered that the levels of intracellular Ca2+ and reactive oxygen species (ROS) were significantly elevated in ß-TC-6 cells following exposure to 100 and 500 µM nicotine, while calcium channel blocker can reverse this effect. Furthermore, the senescence-inducing phenotype was confirmed in rat insulinoma INS-1 cells at a similar dose range, whereas blockade of nAChRs, calcium and ROS led to apparent impairment of senescence. Finally, we found that administration with 100 and 200 µg/mL nicotine in drinking water for 28 days significantly exacerbated aberrant glucose homeostasis in a mouse model of fat-induced T2DM. Of great intrigue, pancreatic ß cells exhibited significantly enhanced senescence following nicotine administration. Taken together, this study suggests that premature senescence plays a pivotal role in nicotine-triggered ß cell destruction and glucose intolerance, providing a theoretical basis for targeted prevention and treatment of smoking-induced T2DM.

Asunto(s)

Senescencia Celular/efectos de los fármacos , Diabetes Mellitus Tipo 2/inducido químicamente , Células Secretoras de Insulina/efectos de los fármacos , Nicotina/toxicidad , Animales , Western Blotting , Calcio/metabolismo , Progresión de la Enfermedad , Relación Dosis-Respuesta a Droga , Ensayo de Inmunoadsorción Enzimática , Glucosa/metabolismo , Células Secretoras de Insulina/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Especies Reactivas de Oxígeno/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , beta-Galactosidasa/metabolismo