Expression and Regulation of Nampt in Human Islets
| Autor: | Dara J. Watkins, Shui Qing Ye, Yun Yan, Karen Kover, Nataliya Kibiryeva, Doug Bittel, Wayne V. Moore, Pei Ying Tong, Lesya Novikova, Jacob Stuhlsatz, Mark A. Clements, Lisa Stehno-Bittel |
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| Jazyk: | angličtina |
| Rok vydání: | 2013 |
| Předmět: |
Male
Proteomics Anatomy and Physiology Immunofluorescence Nicotinamide phosphoribosyltransferase lcsh:Medicine Gene Expression chemistry.chemical_compound Endocrinology Molecular Cell Biology Insulin lcsh:Science Child Nicotinamide Phosphoribosyltransferase Nicotinamide mononucleotide Aged 80 and over Multidisciplinary geography.geographical_feature_category Age Factors Middle Aged Islet medicine.anatomical_structure Child Preschool Medicine Female Pancreas Research Article Protein Binding Adult medicine.medical_specialty Adolescent Immunology Endocrine System Biology Glucagon Islets of Langerhans Young Adult Internal medicine medicine Humans Secretion RNA Messenger Aged Diabetic Endocrinology geography Endocrine Physiology Pancreatic islets lcsh:R Infant Newborn Infant Enzyme Activation Glucose chemistry Gene Expression Regulation Immunologic Techniques lcsh:Q NAD+ kinase Endocrine Cells |
| Zdroj: | PLoS ONE PLoS ONE, Vol 8, Iss 3, p e58767 (2013) |
| ISSN: | 1932-6203 |
| Popis: | Nicotinamide phosphoribosyltransferase (Nampt) is a rate-limiting enzyme in the mammalian NAD+ biosynthesis of a salvage pathway and exists in 2 known forms, intracellular Nampt (iNampt) and a secreted form, extracellular Nampt (eNampt). eNampt can generate an intermediate product, nicotinamide mononucleotide (NMN), which has been reported to support insulin secretion in pancreatic islets. Nampt has been reported to be expressed in the pancreas but islet specific expression has not been adequately defined. The aim of this study was to characterize Nampt expression, secretion and regulation by glucose in human islets. Gene and protein expression of Nampt was assessed in human pancreatic tissue and isolated islets by qRT-PCR and immunofluorescence/confocal imaging respectively. Variable amounts of Nampt mRNA were detected in pancreatic tissue and isolated islets. Immunofluorescence staining for Nampt was found in the exocrine and endocrine tissue of fetal pancreas. However, in adulthood, Nampt expression was localized predominantly in beta cells. Isolated human islets secreted increasing amounts of eNampt in response to high glucose (20 mM) in a static glucose-stimulated insulin secretion assay (GSIS). In addition to an increase in eNampt secretion, exposure to 20 mM glucose also increased Nampt mRNA levels but not protein content. The secretion of eNampt was attenuated by the addition of membrane depolarization inhibitors, diazoxide and nifedipine. Islet-secreted eNampt showed enzymatic activity in a reaction with increasing production of NAD+/NADH over time. In summary, we show that Nampt is expressed in both exocrine and endocrine tissue early in life but in adulthood expression is localized to endocrine tissue. Enzymatically active eNampt is secreted by human islets, is regulated by glucose and requires membrane depolarization. |
| Databáze: | OpenAIRE |
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