Long noncoding RNAs (lncRNAs) are a new class of transcripts that are in general longer than 200 nucleotides and that have no protein-coding potential. The vast majority of vertebrate genomes encode diverse and complex lncRNAs that play... more
Long noncoding RNAs (lncRNAs) are a new class of transcripts that are in general longer than 200 nucleotides and that have no protein-coding potential. The vast majority of vertebrate genomes encode diverse and complex lncRNAs that play regulatory roles at almost every step of gene expression. Recently, increasing evidence has implicated lncRNAs in the pathogenesis of various human diseases. The purpose of the Research Topic, "Emerging roles of long noncoding RNAs in neurological diseases and metabolic disorders", is to bring together leading researchers in the field who, through contributing to an organized and comprehensive collection of peer-reviewed articles, provide a broad perspective on the latest advances in the field. A number of interesting and cutting-edge areas will be covered as below, but this list is not exclusive: - The methodologies and technologies of identifying and studying lncRNAs - LncRNAs in gene-specific transcription - LncRNAs in epigenetic regulation - LncRNAs in post-transcriptional regulation - LncRNAs in disease - Mapping of noncoding single nucleotide polymorphisms associated with disease
Research Interests: Neuroscience, Metabolism, Diabetes, Biology, Beta Cell, and 3 morelncRNA, Q, and Neurological Diseases
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Background: Chronic exposure to elevated levels of saturated fatty acids results in pancreatic β-cell senescence. However, targets and effective agents for preventing stearic acid-induced β-cell senescence are still lacking. Although... more
Background: Chronic exposure to elevated levels of saturated fatty acids results in pancreatic β-cell senescence. However, targets and effective agents for preventing stearic acid-induced β-cell senescence are still lacking. Although melatonin administration can protect β-cells against lipotoxicity through anti-senescence processes, the precise underlying mechanisms still need to be explored. Therefore, we investigated the anti-senescence effect of melatonin on stearic acid-treated mouse β-cells and elucidated the possible role of microRNAs in this process.Methods: β-Cell senescence was identified by measuring the expression of senescence-related genes and senescence-associated β-galactosidase staining. Gain- and loss-of-function approaches were used to investigate the involvement of microRNAs in stearic acid-evoked β-cell senescence and dysfunction. Bioinformatics analyses and luciferase reporter activity assays were applied to predict the direct targets of microRNAs.Results: Long-...
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It has been known for a number of years that only about 2 % of this RNA encodes proteins. However, numerous studies employ-ing both tiling arrays and high-throughput sequencing found that the genome is pervasively transcribed, with most... more
It has been known for a number of years that only about 2 % of this RNA encodes proteins. However, numerous studies employ-ing both tiling arrays and high-throughput sequencing found that the genome is pervasively transcribed, with most DNA copied, at least at some point in time, into RNA. Indeed, Birney et al. (2007) estimated that 93 % of the human genome is transcribed. Because of a dearth of functional information about such tran-scripts, the concept of widespread non-coding regions became the “dark matter ” of the genome (Johnson et al., 2005) and in recent years there has been an explosion of research in this area. Due to technical and theoretical considerations, transcripts longer than 200 nucleotides and lacking the potential to be translated have been coined “long non-coding RNAs ” or lncRNAs. Owing to thousands of these new transcripts that have been identified [The current GENCODE v20 estimates close to 15,000 independent
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OBJECTIVE—Visceral obesity and elevated plasma free fatty acids are predisposing factors for type 2 diabetes. Chronic exposure to these lipids is detrimental for pancreatic �-cells, resulting in reduced insulin content, defective insulin... more
OBJECTIVE—Visceral obesity and elevated plasma free fatty acids are predisposing factors for type 2 diabetes. Chronic exposure to these lipids is detrimental for pancreatic �-cells, resulting in reduced insulin content, defective insulin secretion, and apoptosis. We investigated the involvement in this phenomenon of microRNAs (miRNAs), a class of noncoding RNAs regulating gene expression by sequence-specific inhibition of mRNA translation. RESEARCH DESIGN AND METHODS—We analyzed miRNA expression in insulin-secreting cell lines or pancreatic islets exposed to palmitate for 3 days and in islets from diabetic db/db mice. We studied the signaling pathways triggering the changes in miRNA expression and determined the impact of the miRNAs affected by palmitate on insulin secretion and apoptosis. RESULTS—Prolonged exposure of the �-cell line MIN6B1 and
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We examined the presence of small molecular mass GTP-binding proteins of the Rab3 family in different insulinsecreting cells. Rab3B and Rab3C were identified by western blotting in rat and in human pancreatic islets, in two rat... more
We examined the presence of small molecular mass GTP-binding proteins of the Rab3 family in different insulinsecreting cells. Rab3B and Rab3C were identified by western blotting in rat and in human pancreatic islets, in two rat insulin-secreting cell lines, RINm5F and INS-1, as well as in the hamster cell line HIT-T15. In contrast, Rab3A was detected in rat pancreatic islets as well as in the two insulin-secreting rat cell lines but not in human pancreatic islets and was only barely discernible in HIT-T15 cells. These findings were confirmed by two-dimensional gel electrophoresis followed by GTP-overlay of homogenates of pancreatic islets and of the purified protein. Northern blotting analysis revealed that Rab3D is expressed in the same insulin-secreting cells as Rab3A. Separation of the cells of the rat islets by fluorescence-activated cell sorting demonstrated that Rab3A was exclusively expressed in β-cells. Rab3A was found to be associated with insulin-containing secretory granu...
Research Interests: Biology, Immunohistochemistry, Medicine, Gene expression, Biological Sciences, and 15 moreCell line, Humans, Insulin, Mutation, Animals, Cell, Guanosine Triphosphate, Molecular weight, Hydrolysis, Gtp Binding Proteins, islets of Langerhans, Pancreatic islets, Cricetinae, GTP, and Medical and Health Sciences
Myosin- and Rab-interacting protein (MyRIP), which belongs to the protein kinase A (PKA)–anchoring family, is implicated in hormone secretion. However, its mechanism of action is not fully elucidated. Here we investigate the role of MyRIP... more
Myosin- and Rab-interacting protein (MyRIP), which belongs to the protein kinase A (PKA)–anchoring family, is implicated in hormone secretion. However, its mechanism of action is not fully elucidated. Here we investigate the role of MyRIP in myosin Va (MyoVa)-dependent secretory granule (SG) transport and secretion in pancreatic beta cells. These cells solely express the brain isoform of MyoVa (BR-MyoVa), which is a key motor protein in SG transport. In vitro pull-down, coimmunoprecipitation, and colocalization studies revealed that MyRIP does not interact with BR-MyoVa in glucose-stimulated pancreatic beta cells, suggesting that, contrary to previous notions, MyRIP does not link this motor protein to SGs. Glucose-stimulated insulin secretion is augmented by incretin hormones, which increase cAMP levels and leads to MyRIP phosphorylation, its interaction with BR-MyoVa, and phosphorylation of the BR-MyoVa receptor rabphilin-3A (Rph-3A). Rph-3A phosphorylation on Ser-234 was inhibited...
Research Interests: Biology, Cell Biology, Medicine, B cells, Biological Sciences, and 14 moreGlucose, Insulin Secretion, Mice, cyclic AMP, Animals, Molecular motor proteins, Phosphorylation, Rats, Pancreatic Beta Cell Regeneration, Protein Binding, Plasma Membrane, Secretion, islets of Langerhans, and Medical and Health Sciences
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Research Interests: Biology, Calcium, Cell Biology, Medicine, Biological Sciences, and 15 moreCell line, Humans, Insulin, Epinephrine, Animals, Exocytosis, G protein, Amino Acid Sequence, Gtp Binding Proteins, Mastoparan, islets of Langerhans, Adenosine Triphosphate, Cell membrane permeability, C Peptide, and Medical and Health Sciences
Research Interests: Biochemistry, Chemistry, Kinetics, Biology, Biological Chemistry, and 15 moreMedicine, Biological Sciences, Cell line, Glucose, Insulin, Liver, Animals, Male, Biological, CHEMICAL SCIENCES, Dehydrogenase, Lactate dehydrogenase, islets of Langerhans, Medical and Health Sciences, and In Vitro Techniques
The role of protein kinase C (PKC) in stimulus recognition and insulin secretion was investigated after long-term (24 h) treatment of RINm5F cells with phorbol 12-myristate 13-acetate (PMA). Three methods revealed that PKC was no longer... more
The role of protein kinase C (PKC) in stimulus recognition and insulin secretion was investigated after long-term (24 h) treatment of RINm5F cells with phorbol 12-myristate 13-acetate (PMA). Three methods revealed that PKC was no longer detectable, and PMA-induced insulin secretion was abolished. Such PKC-deficient cells displayed enhanced insulin secretion (2-6-fold) in response to vasopressin and carbachol (activating phospholipase C) as well as to D-glyceraldehyde and alanine (promoting membrane depolarization and voltage-gated Ca2+ influx). Insulin release stimulated by 1-oleoyl-2-acetylglycerol (OAG) was also greater in PKC-deficient cells. OAG caused membrane depolarization and raised the cytosolic Ca2+ concentration ([Ca2+]i), both of which were unaffected by PKC down-regulation. Except for that caused by vasopressin, the secretagogue-induced [Ca2+]i elevations were similar in control and PKC-depleted cells. The [Ca2+]i rise evoked by vasopressin was enhanced during the early...
Research Interests: Endocrinology, Kinetics, Biology, Calcium, Medicine, and 15 moreBiological Sciences, Cell line, Internal Medicine, Insulin, cyclic AMP, Animals, Biochemical, CHEMICAL SCIENCES, Alanine, Diglycerides, Depolarization, Cell Membrane, Medical and Health Sciences, Arginine Vasopressin, and Electric stimulation
SNAP-25 is expressed in neurons and endocrine cells and is essential for exocytosis of neurotransmitters and peptide hormones. It has been shown to be involved in several interactions with other proteins of the secretion machinery. Here... more
SNAP-25 is expressed in neurons and endocrine cells and is essential for exocytosis of neurotransmitters and peptide hormones. It has been shown to be involved in several interactions with other proteins of the secretion machinery. Here we show that SNAP-25 can self-associate to form a disulfide-linked complex. Complex formation is facilitated in vitro (in concentrated extracts or by immunoprecipitation). SNAP-25 complexes, however, also form when intact cells are treated with a membrane-permeable crosslinker indicating that SNAP-25 molecules exist in close proximity in vivo and could form complexes spontaneously. We also show that monomeric SNAP-25 and disulfide-linked SNAP-25 complexes are palmitoylated and that both can be cleaved by botulinum neurotoxin E.
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Subcellular distribution and function of Rab3A, B, C, and D isoforms in insulin-secreting cells IEZZI-BAKHTIARI, Mariella, et al. Insulin-secreting cells express four GTPases of the Rab3 family. After separation of extracts of INS-1 cells... more
Subcellular distribution and function of Rab3A, B, C, and D isoforms in insulin-secreting cells IEZZI-BAKHTIARI, Mariella, et al. Insulin-secreting cells express four GTPases of the Rab3 family. After separation of extracts of INS-1 cells on a sucrose density gradient, the bulk of the A, B, and C isoforms was recovered in the fractions enriched in insulin-containing secretory granules. Rab3D was also mainly associated with secretory granules, but a fraction of this isoform was localized on lighter organelles. Analyses by confocal microscopy of immunostained HIT-T15 cells transfected with epitope-tagged constructs confirmed the distribution of the Rab3 isoforms. Transfection of HIT-T15 cells with GTPase-deficient mutants of the Rab3 isoforms decreased nutrient-induced insulin release to different degrees (D>B>A>C), while overexpression of Rab3 wild types had minor or no effects. Expression of the same Rab3 mutants in PC12 cells provoked an inhibition of K+-stimulated secreti...
Postnatal β-cell maturation is associated with islet-specific microRNA changes induced by nutrient shifts at weaning
Exocytosis.- Regulation of SNARE Complex Assembly by Second Messengers.- Rab GTPases and Their Role in the Control of Exocytosis.- The Role of Synaptotagmin and Synaptotagmin-Like Protein (Slp) in Regulated Exocytosis.- The Synapsins and... more
Exocytosis.- Regulation of SNARE Complex Assembly by Second Messengers.- Rab GTPases and Their Role in the Control of Exocytosis.- The Role of Synaptotagmin and Synaptotagmin-Like Protein (Slp) in Regulated Exocytosis.- The Synapsins and the Control of Neuroexocytosis.- Phospholipase D.- Lipid Rafts as Regulators of SNARE Activity and Exocytosis.- Mast Cells as a Model of Nonneuroendocrine Exocytosis.- Acrosomal Exocytosis.- Nonsecretory, Regulated Exocytosis.- Adaptation of the Secretory Machinery to Pathophysiological Conditions.
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Pancreatic β-cells are highly specialized cells committed to secrete insulin in response to changes in the level of nutrients, hormones and neurotransmitters. Chronic exposure to elevated concentrations of glucose, fatty acids or... more
Pancreatic β-cells are highly specialized cells committed to secrete insulin in response to changes in the level of nutrients, hormones and neurotransmitters. Chronic exposure to elevated concentrations of glucose, fatty acids or inflammatory mediators can result in modifications in β-cell gene expression that alter their functional properties. This can lead to the release of insufficient amount of insulin to cover the organism's needs, and thus to the development of diabetes mellitus. Although most of the studies carried out in the last decades to elucidate the causes of β-cell dysfunction under disease conditions have focused on protein-coding genes, we now know that insulin-secreting cells also contain thousands of molecules of RNA that do not encode polypeptides but play key roles in the acquisition and maintenance of a highly differentiated state. In this review, we will highlight the involvement of long non-coding RNAs (lncRNAs), a particular class of non-coding transcripts, in the differentiation of β-cells and in the regulation of their specialized tasks. We will also discuss the crosstalk between the activities of lncRNAs and microRNAs and present the emerging evidence of a potential contribution of particular lncRNAs to the development of both type 1 and type 2 diabetes.
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Low-molecular-mass GTP-binding proteins of the ras family were analysed by [32P]GTP binding after PAGE and transfer to nitrocellulose membranes. By this technique, several GTP-binding proteins in the 20-30 kDa range were detected in both... more
Low-molecular-mass GTP-binding proteins of the ras family were analysed by [32P]GTP binding after PAGE and transfer to nitrocellulose membranes. By this technique, several GTP-binding proteins in the 20-30 kDa range were detected in both cytosolic and microsomal fractions of RINm5F cells. One of these, displaying an apparent molecular mass of about 20 kDa and a pI of 6.7, was mainly cytosolic and was shown to be the ADP-ribosylation factor (ARF) by using specific antibodies. When permeabilized RINm5F cells were incubated with the stable GTP analogues guanosine 5′-[gamma-thio]triphosphate (GTP[S]) and guanosine 5′-[beta gamma-imido]triphosphate (p[NH]ppG) the amount of ARF increased in a fraction containing both Golgi and plasma-membrane markers, but not in the fraction containing secretory granules, mitochondria and lysosomes. GTP, GDP and its beta-thio analogue did not enhance ARF binding to membranes, smg25/rab3 and rho, as well as all the other small GTP-binding proteins detected...
Research Interests: Biochemistry, Biology, Membrane Proteins, Medicine, Western blotting, and 13 moreBiological Sciences, Cell line, Biochemical, CHEMICAL SCIENCES, Guanosine Triphosphate, Molecular weight, Two-Dimensional Gel Electrophoresis, G protein, Gtp Binding Proteins, Cell Membrane, Cell membrane permeability, GTP, and Medical and Health Sciences
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Research Interests: Biology, Medicine, Cell line, Humans, Female, and 10 morePhosphorylation, Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis, Heat Shock Proteins, Molecular weight, Growth Inhibition, Biochemistry and cell biology, Cell Membrane, Breast Neoplasms, Protein Kinase C, and Medical biochemistry and metabolomics
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Long non-coding RNAs (lncRNAs) contribute to diverse cellular functions and the dysregulation of their expression or function can contribute to diseases, including diabetes. The contributions of lncRNAs to β-cell development, function and... more
Long non-coding RNAs (lncRNAs) contribute to diverse cellular functions and the dysregulation of their expression or function can contribute to diseases, including diabetes. The contributions of lncRNAs to β-cell development, function and survival has been extensively studied in vitro. However, very little is currently known on the in vivo roles of lncRNAs in the regulation of glucose and insulin homeostasis. Here we investigated the impact of loss-of-function in mice of the lncRNA A830019P07Rik, hereafter P07Rik, which was previously reported to be associated with reduced plasma insulin levels. Compared with wild-type littermates, male and female P07Rik mutant mice did not show any defect in glycaemia and plasma insulin levels in both fed and fasted state. Furthermore, P07Rik mutant mice displayed similar glucose and insulin levels in response to an intra-peritoneal glucose tolerance test. Ex vivo, islets from mutant P07Rik released similar amount of insulin in response to increase...
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Context Hyperparathyroidism is associated with hypercalcemia and the excess of parathyroid hormone secretion; however, the alterations in molecular pattern of functional genes during parathyroid tumorigenesis have not been unraveled. We... more
Context Hyperparathyroidism is associated with hypercalcemia and the excess of parathyroid hormone secretion; however, the alterations in molecular pattern of functional genes during parathyroid tumorigenesis have not been unraveled. We aimed at establishing transcriptional patterns of normal and pathological parathyroid glands (PGs) in sporadic primary (HPT1) and secondary hyperparathyroidism (HPT2). Objective To evaluate dynamic alterations in molecular patterns as a function of the type of PG pathology, a comparative transcript analysis was conducted in subgroups of healthy samples, sporadic HPT1 adenoma and hyperplasia, and HPT2. Design Normal, adenomatous, HPT1, and HPT2 hyperplastic PG formalin-fixed paraffin-embedded samples were subjected to NanoString analysis. In silico microRNA (miRNA) analyses and messenger RNA–miRNA network in PG pathologies were conducted. Individual messenger RNA and miRNA levels were assessed in snap-frozen PG samples. Results The expression levels o...
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Glucose-induced insulin secretion, a peculiar property of fully matureβ-cells, is only achieved after birth and is preceded by a phase of intense proliferation. These events occurring in the neonatal period are decisive for the... more
Glucose-induced insulin secretion, a peculiar property of fully matureβ-cells, is only achieved after birth and is preceded by a phase of intense proliferation. These events occurring in the neonatal period are decisive for the establishment of an appropriate functionalβ-cell mass that provides the required insulin throughout life. However, key regulators of gene expression involved in cellular reprogramming along pancreatic islet maturation remain to be elucidated. The present study addressed this issue by mapping open chromatin regions in newborn versus adult rat islets using the ATAC-seq assay. Accessible regions were then correlated with the expression profiles of mRNAs to unveil the regulatory networks governing functional islet maturation. This led to the identification of Scrt1, a novel transcriptional repressor controllingβ-cell proliferation.
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The murine mast cell line PB-3c is dependent on interleukin 3 (IL-3) with respect to survival and proliferation. These cells also require IL-3 to display antigen-mediated serotonin release, which is coupled to a transient increase of... more
The murine mast cell line PB-3c is dependent on interleukin 3 (IL-3) with respect to survival and proliferation. These cells also require IL-3 to display antigen-mediated serotonin release, which is coupled to a transient increase of cytosolic free calcium ([Ca2+]i). The antigen-mediated exocytosis is inhibited by phorbol 12-tetradecanoate 13-acetate (PTA), an activator of phospholipid/Ca2+-sensitive protein kinase. In contrast, the malignant mast cell variant PB-1 is IL-3 independent with respect to proliferation but is unable to undergo antigen-mediated exocytosis. Yet this cell line exhibits basal levels of [Ca2+]i, serotonin content, and numbers of IgE receptors comparable to those of PB-3c cells. Subcellular distribution studies revealed that the specific activity of cytosolic protein kinase C of PB-1 cells was only 40% of that found in PB-3c cells. Furthermore, the PB-1 cells showed a significantly higher specific activity of membrane-bound protein kinase C than PB-3c cells. S...
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Inflammatory β-cell failure contributes to type 1 and type 2 diabetes pathogenesis. Pro-inflammatory cytokines cause β-cell dysfunction and apoptosis, and lysine deacetylase inhibitors (KDACi) prevent β-cell failure in vitro and in vivo,... more
Inflammatory β-cell failure contributes to type 1 and type 2 diabetes pathogenesis. Pro-inflammatory cytokines cause β-cell dysfunction and apoptosis, and lysine deacetylase inhibitors (KDACi) prevent β-cell failure in vitro and in vivo, in part by reducing NF-κB transcriptional activity. We investigated the hypothesis that the protective effect of KDACi involves transcriptional regulation of microRNAs (miRs), potential new targets in diabetes treatment. Insulin-producing INS1 cells were cultured with or without the broad-spectrum KDACi Givinostat, prior to exposure to the pro-inflammatory cytokines IL-1β and IFN-γ for 6 h or 24 h, and miR expression was profiled with miR array. Thirteen miRs (miR-7a-2-3p, miR-29c-3p, miR-96-5p, miR-101a-3p, miR-140-5p, miR-146a-5p, miR-146b-5p, miR-340-5p, miR-384-5p, miR-455-5p, miR-466b-2-3p, miR-652-5p, and miR-3584-5p) were regulated by both cytokines and Givinostat, and nine were examined by qRT-PCR. miR-146a-5p was strongly regulated by cytok...
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Type 1 diabetes is an autoimmune disease initiated by the invasion of pancreatic islets by immune cells that selectively kill the β cells. We found that rodent and human T lymphocytes release exosomes containing the microRNAs (miRNAs)... more
Type 1 diabetes is an autoimmune disease initiated by the invasion of pancreatic islets by immune cells that selectively kill the β cells. We found that rodent and human T lymphocytes release exosomes containing the microRNAs (miRNAs) miR-142-3p, miR-142-5p, and miR-155, which can be transferred in active form to β cells favoring apoptosis. Inactivation of these miRNAs in recipient β cells prevents exosome-mediated apoptosis and protects non-obese diabetic (NOD) mice from diabetes development. Islets from protected NOD mice display higher insulin levels, lower insulitis scores, and reduced inflammation. Looking at the mechanisms underlying exosome action, we found that T lymphocyte exosomes trigger apoptosis and the expression of genes involved in chemokine signaling, including Ccl2, Ccl7, and Cxcl10, exclusively in β cells. The induction of these genes may promote the recruitment of immune cells and exacerbate β cell death during the autoimmune attack. Our data point to exosomal-mi...
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Small G-proteins (SMGs) require isoprenylation for their association with membranes. We have examined protein isoprenylation, subcellular distribution of SMGs, cytosolic Ca2+ changes and insulin secretion in HIT-T15 cells after treatment... more
Small G-proteins (SMGs) require isoprenylation for their association with membranes. We have examined protein isoprenylation, subcellular distribution of SMGs, cytosolic Ca2+ changes and insulin secretion in HIT-T15 cells after treatment with lovastatin, which inhibits the production of isoprenoids by blocking mevalonate production by 3-hydroxy-3-methylglutaryl-CoA reductase. Numerous proteins in the 20-70 kDa range were found to be isoprenylated. Most of these proteins co-migrated with SMGs (21-27 kDa). Lovastatin treatment (25 microM, 24 h) decreased protein isoprenylation and affected the distribution of several SMGs, causing a large accumulation in the cytosol and a detectable decrease in membranes. Lovastatin selectively attenuated the potentiating action of bombesin and vasopressin, which activate phospholipase C in these cells, on insulin secretion stimulated by nutrients (glucose + leucine + glutamine). This lovastatin effect was overcome by mevalonate. Insulin secretion sti...
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The exocytotic release of potent hormones is a tightly controlled process. Its direct regulation without the involvement of second messengers would ensure rapid signal processing. In streptolysin O-permeabilized insulin-secreting cells, a... more
The exocytotic release of potent hormones is a tightly controlled process. Its direct regulation without the involvement of second messengers would ensure rapid signal processing. In streptolysin O-permeabilized insulin-secreting cells, a preparation allowing dialysis of cytosolic macromolecules, activation of alpha 2-adrenergic receptors caused pertussis toxin-sensitive inhibition of calcium-induced exocytosis. This inhibition was mimicked very efficiently by the use of specific receptor-mimetic peptides, indicating the involvement of Gi and, to a lesser extent, of G(o). The regulation was exerted beyond the ATP-dependent step of exocytosis. In addition, low nanomolar amounts of pre-activated Gi/G(o) directly inhibited exocytosis. As transient overexpression of constitutively active mutants of G alpha i1, G alpha i2, G alpha i3 and G alpha o2 but not of G alpha o1 reproduced this regulation, the G alpha subunit alone is sufficient to induce inhibition. These results define exocytos...
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Research Interests: Biology, Long Noncoding Rna, Medicine, Cell line, Insulin, and 12 moreMice, Animals, Clinical Sciences, Public health systems and services research, Disease Progression, Beta Cell, Type 2 Diabetes Mellitus, islets of Langerhans, NOD mice, nod, Paediatrics and reproductive medicine, and prediabetic state
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... tandem in the C-terminal region of C-type tandem C2 proteins, including synaptotagmins (Syts),synaptotagmin ... Synaptotagmin and Sip in Regulated Exocytosis ... exocytosis by PC 12 cells, because Syt I-deficient PCI2 cells display... more
... tandem in the C-terminal region of C-type tandem C2 proteins, including synaptotagmins (Syts),synaptotagmin ... Synaptotagmin and Sip in Regulated Exocytosis ... exocytosis by PC 12 cells, because Syt I-deficient PCI2 cells display normal hormone secretion activity, '^ indicating ...
ABSTRACT The prelims comprise: * Exocytosis of Insulin from. the Pancreatic β-cell * Permeabilization of Insulin-secreting Cells * Transient Cotransfection Assay for Exocytosis * Tetanus Toxin as a Tool for Studying the Role of VAMPs in... more
ABSTRACT The prelims comprise: * Exocytosis of Insulin from. the Pancreatic β-cell * Permeabilization of Insulin-secreting Cells * Transient Cotransfection Assay for Exocytosis * Tetanus Toxin as a Tool for Studying the Role of VAMPs in Exocytosis * The Use of Other Clostridial Neurotoxins for the Study of Exocytosis * Reagents and Chemicals
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The name of the eighth author was spelled incorrectly. The correct name is: Amar Abderrahmani.
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Granuphilin/Slp-4 is a member of the synaptotagmin-like protein family expressed in pancreatic β-cells and in the pituitary gland. We show by confocal microscopy that both granuphilin-a and -b colocalize with insulin-containing secretory... more
Granuphilin/Slp-4 is a member of the synaptotagmin-like protein family expressed in pancreatic β-cells and in the pituitary gland. We show by confocal microscopy that both granuphilin-a and -b colocalize with insulin-containing secretory granules positioned at the periphery of pancreatic β-cells. Overexpression of granuphilins in insulin-secreting cell lines caused a profound inhibition of stimulus-induced exocytosis. Granuphilins were found to bind to two components of the secretory machinery of pancreatic β-cells, the small GTP-binding protein Rab3 and the solubleN-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)–binding protein Munc-18. The interaction with Rab3 occurred only with the GTP-bound form of the protein and was prevented by a point mutation in the effector domain of the GTPase. Structure-function studies using granuphilin-b mutants revealed that complete loss of Rab3 binding is associated with a reduction in the capacity to inhibit exocytosis. Howeve...
Research Interests: Molecular Biology, Biology, Cell Biology, Biological Sciences, Antibodies, and 15 moreAnimals, C2H2 zinc fingers, Polymerase Chain Reaction, Plasmids, Molecular cloning, Rats, Exocytosis, Protein Conformation, Base Sequence, Subcellular Fractions, Recombinant Proteins, islets of Langerhans, binding sites, reverse transcriptase polymerase chain reaction, and Medical and Health Sciences
The neuronal-specific protein complexin I (CPX I) plays an important role in controlling the Ca2+-dependent neurotransmitter release. Since insulin exocytosis and neurotransmitter release rely on similar molecular mechanisms and that... more
The neuronal-specific protein complexin I (CPX I) plays an important role in controlling the Ca2+-dependent neurotransmitter release. Since insulin exocytosis and neurotransmitter release rely on similar molecular mechanisms and that pancreatic β-cells and neuronal cells share the expression of many restricted genes, we investigated the potential role of CPX I in insulin-secreting cells. We found that pancreatic islets and several insulin-secreting cell lines express high levels of CPX I. The β-cell expression of CPX I is mediated by the presence of a neuron restrictive silencer element located within the regulatory region of the gene. This element bound the transcriptional repressor REST, which is found in most cell types with the exception of mature neuronal cells and β-cells. Overexpression of CPX I or silencing of the CPX I gene (Cplx1) by RNA interference led to strong impairment in β-cell secretion in response to nutrients such as glucose, leucine and KCl. This effect was dete...
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ABSTRACT Introduction La protéine islet brain 1 (IB1) joue un rôle clé dans les effets prodigués par le mimétique du glucagon-like peptide 1, l’exendin-4 (ex-4), sur la survie des cellules bêta et très certainement sur l’expression de... more
ABSTRACT Introduction La protéine islet brain 1 (IB1) joue un rôle clé dans les effets prodigués par le mimétique du glucagon-like peptide 1, l’exendin-4 (ex-4), sur la survie des cellules bêta et très certainement sur l’expression de l’insuline. Ce rôle est essentiellement lié au contrôle de la voie de signalisation c-Jun N-terminal kinase (JNK). En outre, IB1 contrôle la sécrétion de l’insuline de manière indépendante du métabolisme du glucose et de la voie de JNK. Ce mécanisme contribuerait aussi aux effets sécrétagogues du GLP-1 et de ces analogues mimétiques. L’objectif de ce travail fut de comprendre le mécanisme par lequel IB1 contrôle la sécrétion de l’insuline. Matériels et méthodes Des ARN interférant dirigés spécifiquement contre IB1 ont été introduits dans les cellules sécrétrices d’insuline de rat INS-1Evia un vecteur lentiviral. L’insuline contenue dans les cellules, et relâchée, est mesurée par EIA. Les protéines totales des cellules ont été sujettes à une analyse protéomique et au micro-séquencage. Résultats La suppression sélective d’IB1 entraîne une perte de sécrétion de l’insuline. Cette perte de fonction est associée avec un profil protéomique qui diffère de celui des cellules contrôles. L’annexine a2 (Anxa2) est une des protéines dont les niveaux s’effondrent dans les cellules où IB1 est diminuée. Anxa2 contrôle la sécrétion des cellules neuroendocrines, en réorganisant les filaments d’actine. La réduction de l’expression de l’Anxa2 par ARN interférence mime les effets de la suppression d’IB1 sur la sécrétion de l’insuline. Conclusion IB1 contrôle la sécrétion de l’insuline en maintenant les niveaux de l’Anxa2.