Transgenic overexpression of microRNA-30d in pancreatic beta-cells progressively regulates beta-cell function and identity.
Ontology highlight
ABSTRACT:
SUBMITTER: Mao Y
PROVIDER: S-EPMC9279310 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Dysfunctional microRNA (miRNA) networks contribute to inappropriate responses following pathological stress and are the underlying cause of several disease conditions. In pancreatic ? cells, miRNAs have been largely unstudied and little is known about how specific miRNAs regulate glucose-stimulated insulin secretion (GSIS) or impact the adaptation of ? cell function to metabolic stress. In this study, we determined that miR-7 is a negative regulator of GSIS in ? cells. Using Mir7a2 deficient mice, we revealed that miR-7a2 regulates ? cell function by directly regulating genes that control late stages of insulin granule fusion with the plasma membrane and ternary SNARE complex activity. Transgenic mice overexpressing miR-7a in ? cells developed diabetes due to impaired insulin secretion and ? cell dedifferentiation. Interestingly, perturbation of miR-7a expression in ? cells did not affect proliferation and apoptosis, indicating that miR-7 is dispensable for the maintenance of endocrine ? cell mass. Furthermore, we found that miR-7a levels are decreased in obese/diabetic mouse models and human islets from obese and moderately diabetic individuals with compensated ? cell function. Our results reveal an interconnecting miR-7 genomic circuit that regulates insulin granule exocytosis in pancreatic ? cells and support a role for miR-7 in the adaptation of pancreatic ? cell function in obesity and type 2 diabetes.
| S-EPMC4038573 | biostudies-literature
Project description:Diabetic cardiomyopathy is a common cardiac condition in patients with diabetes mellitus, which can result in cardiac hypertrophy and subsequent heart failure, associated with pyroptosis, the pro-inflammatory programmed cell death. MicroRNAs (miRNAs), small endogenous non-coding RNAs, have been shown to be involved in diabetic cardiomyopathy. However, whether miRNAs regulate pyroptosis in diabetic cardiomyopathy remains unknown. Our study revealed that mir-30d expression was substantially increased in streptozotocin (STZ)-induced diabetic rats and in high-glucose-treated cardiomyocytes as well. Upregulation of mir-30d promoted cardiomyocyte pyroptosis in diabetic cardiomyopathy; conversely, knockdown of mir-30d attenuated it. In an effort to understand the signaling mechanisms underlying the pro-pyroptotic property of mir-30d, we found that forced expression of mir-30d upregulated caspase-1 and pro-inflammatory cytokines IL-1? and IL-18. Moreover, mir-30d directly repressed foxo3a expression and its downstream protein, apoptosis repressor with caspase recruitment domain (ARC). Furthermore, silencing ARC by siRNA mimicked the action of mir-30d: upregulating caspase-1 and inducing pyroptosis. These findings promoted us to propose a new signaling pathway leading to cardiomyocyte pyroptosis under hyperglycemic conditions: mir-30d??foxo3a?? ARC??caspase-1??IL-1?, IL-18??pyroptosis?. Therefore, mir-30d may be a promising therapeutic target for the management of diabetic cardiomyopathy.
| S-EPMC4237254 | biostudies-literature
Project description:A sustained increase in intracellular Ca2+ concentration (referred to hereafter as excitotoxicity), brought on by chronic metabolic stress, may contribute to pancreatic β-cell failure. To determine the additive effects of excitotoxicity and overnutrition on β-cell function and gene expression, we analyzed the impact of a high-fat diet (HFD) on Abcc8 knockout mice. Excitotoxicity caused β-cells to be more susceptible to HFD-induced impairment of glucose homeostasis, and these effects were mitigated by verapamil, a Ca2+ channel blocker. Excitotoxicity, overnutrition, and the combination of both stresses caused similar but distinct alterations in the β-cell transcriptome, including additive increases in genes associated with mitochondrial energy metabolism, fatty acid β-oxidation, and mitochondrial biogenesis and their key regulator Ppargc1a Overnutrition worsened excitotoxicity-induced mitochondrial dysfunction, increasing metabolic inflexibility and mitochondrial damage. In addition, excitotoxicity and overnutrition, individually and together, impaired both β-cell function and identity by reducing expression of genes important for insulin secretion, cell polarity, cell junction, cilia, cytoskeleton, vesicular trafficking, and regulation of β-cell epigenetic and transcriptional program. Sex had an impact on all β-cell responses, with male animals exhibiting greater metabolic stress-induced impairments than females. Together, these findings indicate that a sustained increase in intracellular Ca2+, by altering mitochondrial function and impairing β-cell identity, augments overnutrition-induced β-cell failure.
| S-EPMC7809715 | biostudies-literature
Project description:Pancreatic beta cells, organized in the islets of Langerhans, sense glucose and secrete appropriate amounts of insulin. We have studied the roles of LKB1, a conserved kinase implicated in the control of cell polarity and energy metabolism, in adult beta cells. LKB1-deficient beta cells show a dramatic increase in insulin secretion in vivo. Histologically, LKB1-deficient beta cells have striking alterations in the localization of the nucleus and cilia relative to blood vessels, suggesting a shift from hepatocyte-like to columnar polarity. Additionally, LKB1 deficiency causes a 65% increase in beta cell volume. We show that distinct targets of LKB1 mediate these effects. LKB1 controls beta cell size, but not polarity, via the mTOR pathway. Conversely, the precise position of the beta cell nucleus, but not cell size, is controlled by the LKB1 target Par1b. Insulin secretion and content are restricted by LKB1, at least in part, via AMPK. These results expose a molecular mechanism, orchestrated by LKB1, for the coordinated maintenance of beta cell size, form, and function.
| S-EPMC2790403 | biostudies-literature
Project description:Insulin/IGF-I signaling regulates the metabolism of most mammalian tissues including pancreatic islets. To dissect the mechanisms linking insulin signaling with mitochondrial function, we first identified a mitochondria-tethering complex in beta-cells that included glucokinase (GK), and the pro-apoptotic protein, BAD(S). Mitochondria isolated from beta-cells derived from beta-cell specific insulin receptor knockout (betaIRKO) mice exhibited reduced BAD(S), GK and protein kinase A in the complex, and attenuated function. Similar alterations were evident in islets from patients with type 2 diabetes. Decreased mitochondrial GK activity in betaIRKOs could be explained, in part, by reduced expression and altered phosphorylation of BAD(S). The elevated phosphorylation of p70S6K and JNK1 was likely due to compensatory increase in IGF-1 receptor expression. Re-expression of insulin receptors in betaIRKO cells partially restored the stoichiometry of the complex and mitochondrial function. These data indicate that insulin signaling regulates mitochondrial function and have implications for beta-cell dysfunction in type 2 diabetes.
| S-EPMC2776992 | biostudies-literature
Project description:Despite significant research, mechanisms underlying the failure of islet beta cells that result in type 2 diabetes (T2D) are still under investigation. Here, we report that Sox9, a transcriptional regulator of pancreas development, also functions in mature beta cells. Our results show that Sox9-depleted rodent beta cells have defective insulin secretion, and aging animals develop glucose intolerance, mimicking the progressive degeneration observed in T2D. Using genome editing in human stem cells, we show that beta cells lacking SOX9 have stunted first-phase insulin secretion. In human and rodent cells, loss of Sox9 disrupts alternative splicing and triggers accumulation of non-functional isoforms of genes with key roles in beta cell function. Sox9 depletion reduces expression of protein-coding splice variants of the serine-rich splicing factor arginine SRSF5, a major splicing enhancer that regulates alternative splicing. Our data highlight the role of SOX9 as a regulator of alternative splicing in mature beta cell function.
| S-EPMC10796970 | biostudies-literature
Project description:The impairment of pancreatic β-cells function is partly caused by lipotoxicity, which aggravates the development of type 2 diabetes mellitus. Activator Protein 1 member JunD modulates apoptosis and oxidative stress. Recently, it has been found that JunD regulates lipid metabolism in hepatocytes and cardiomyocytes. Here, we studied the role of JunD in pancreatic β-cells. The lipotoxic effects of palmitic acid on INS-1 cells were measured, and JunD small-interfering RNA was used to assess the effect of JunD in regulating lipid metabolism and insulin secretion. The results showed that palmitic acid stimulation induced the overexpression of JunD, impaired glucose-stimulated insulin secretion, and increased intracellular lipid accumulation of β-cells. Moreover, the gene expression involved in lipid metabolism (Scd1, Fabp4, Fas, Cd36, Lpl, and Plin5) was upregulated, while gene expression involved in the pancreatic β-cells function (such as Pdx1, Nkx6.1, Glut2, and Irs-2) was decreased. Gene silencing of JunD reversed the lipotoxic effects induced by PA on β-cells. These results suggested that JunD regulated the function of pancreatic β-cells by altering lipid accumulation.
| S-EPMC8322846 | biostudies-literature
Project description:In addition to its primary role in regulating glucose production from the liver, glucagon has many other actions, reflected by the wide tissue distribution of the glucagon receptor (Gcgr). To investigate the role of glucagon in the regulation of insulin secretion and whole body glucose homeostasis in vivo, we generated mice overexpressing the Gcgr specifically on pancreatic beta-cells (RIP-Gcgr). In vivo and in vitro insulin secretion in response to glucagon and glucose was increased 1.7- to 3.9-fold in RIP-Gcgr mice compared with controls. Consistent with the observed increase in insulin release in response to glucagon and glucose, the glucose excursion resulting from both a glucagon challenge and intraperitoneal glucose tolerance test (IPGTT) was significantly reduced in RIP-Gcgr mice compared with controls. However, RIP-Gcgr mice display similar glucose responses to an insulin challenge. beta-Cell mass and pancreatic insulin content were also increased (20 and 50%, respectively) in RIP-Gcgr mice compared with controls. When fed a high-fat diet (HFD), both control and RIP-Gcgr mice developed similar degrees of obesity and insulin resistance. However, the severity of both fasting hyperglycemia and impaired glucose tolerance (IGT) were reduced in RIP-Gcgr mice compared with controls. Furthermore, the insulin response of RIP-Gcgr mice to an IPGTT was twice that of controls when fed the HFD. These data indicate that increased pancreatic beta-cell expression of the Gcgr increased insulin secretion, pancreatic insulin content, beta-cell mass, and, when mice were fed a HFD, partially protected against hyperglycemia and IGT.
| S-EPMC2739695 | biostudies-literature
Project description:In response to fasting or hyperglycemia, the pancreatic β-cell alters its output of secreted insulin; however, the pathways governing this adaptive response are not entirely established. Although the precise role of microRNAs (miRNAs) is also unclear, a recurring theme emphasizes their function in cellular stress responses. We recently showed that miR-184, an abundant miRNA in the β-cell, regulates compensatory proliferation and secretion during insulin resistance. Consistent with previous studies showing miR-184 suppresses insulin release, expression of this miRNA was increased in islets after fasting, demonstrating an active role in the β-cell as glucose levels lower and the insulin demand ceases. Additionally, miR-184 was negatively regulated upon the administration of a sucrose-rich diet in Drosophila, demonstrating strong conservation of this pathway through evolution. Furthermore, miR-184 and its target Argonaute2 remained inversely correlated as concentrations of extracellular glucose increased, underlining a functional relationship between this miRNA and its targets. Lastly, restoration of Argonaute2 in the presence of miR-184 rescued suppression of miR-375-targeted genes, suggesting these genes act in a coordinated manner during changes in the metabolic context. Together, these results highlight the adaptive role of miR-184 according to glucose metabolism and suggest the regulatory role of this miRNA in energy homeostasis is highly conserved.
| S-EPMC4536436 | biostudies-literature
Project description:BACKGROUND:Nucleolin (NCL) is the most abundant RNA-binding protein in the cell nucleolus and plays an important role in chromatin stability, ribosome assembly, ribosomal RNA maturation, ribosomal DNA transcription, nucleocytoplasmic transport, and regulation of RNA stability and translation efficiency. In addition to its anti-apoptotic properties, the underlying mechanisms associated with NCL-related roles in different cellular processes remain unclear. In this study, the effect of NCL on microRNA (miRNA) expression was evaluated by generating transgenic mice with myocardial overexpression of NCL and by analyzing microarrays of mature and precursor miRNAs from mice. METHODS:Using microinjection of alpha-MyHc clone 26-NCL plasmids, we generated transgenic mice with myocardial overexpression of NCL firstly, and then mature and precursor miRNAs expression profiles were analyzed in NCL transgenic mice (n = 3) and wild-type (WT) mice (n = 3) by miRNA microarrays. Statistical Package for the Social Sciences version 16.0 software (SPSS, Inc., Chicago, IL, USA) was used to perform Student's t-test, and statistical significance was determined at P < 0.05. RESULTS:Several miRNAs were found to be differentially expressed, of which 11 were upregulated and 4 were downregulated in transgenic mice with myocardial overexpression of NCL compared to those in WT mice. Several differentially expressed miRNAs were subsequently confirmed and quantified by real-time quantitative reverse transcription-polymerase chain reaction. Bioinformatics analysis was used for the prediction of miRNA targets. Furthermore, in vitro experiments showed that NCL regulated miR-21 expression following hydrogen peroxide preconditioning. CONCLUSIONS:Myocardial-protection mechanisms exerted by NCL might be mediated by the miRNAs identified in this study.
| S-EPMC5798056 | biostudies-literature