INGAP-PP up-regulates the expression of genes and proteins related to K+ ATP channels and ameliorates Ca2+ handling in cultured adult rat islets
| Autor: | Juan José Gagliardino, Hector Herminio del Zotto, Helena C. Barbosa, Antonio C. Boschero, Everardo M. Carneiro, José Roberto Bosqueiro, Alex Rafacho, Kelly Elizeu da Silva, María Inés Borelli, Luiz Fabrizio Stoppiglia |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
endocrine system
medicine.medical_specialty Time Factors Physiology medicine.medical_treatment Tolbutamide Clinical Biochemistry Blotting Western Gene Expression Pancreatitis-Associated Proteins Biology Biochemistry Potassium Chloride Tissue Culture Techniques Cellular and Molecular Neuroscience Islets of Langerhans Endocrinology KATP Channels Internal medicine Gene expression medicine Animals Insulin Secretion Potassium Channels Inwardly Rectifying Rats Wistar Pancreatic hormone geography geography.geographical_feature_category Reverse Transcriptase Polymerase Chain Reaction Kir6.2 Islet Peptide Fragments Insulin oscillation Rats Glucose Hepatocyte Nuclear Factor 3-beta Cytokines Calcium medicine.drug |
| Zdroj: | Regulatory peptides. 148(1-3) |
| ISSN: | 0167-0115 |
| Popis: | Islet Neogenesis Associated Protein (INGAP) increases pancreatic β-cell mass and potentiates glucose-induced insulin secretion. Here, we investigated the effects of the pentadecapeptide INGAP-PP in adult cultured rat islets upon the expression of proteins constitutive of the K + ATP channel, Ca 2+ handling, and insulin secretion. The islets were cultured in RPMI medium with or without INGAP-PP for four days. Thereafter, gene (RT-PCR) and protein expression (Western blotting) of Foxa2, SUR1 and Kir6.2, cytoplasmic Ca 2+ ([Ca 2+ ] i ), static and dynamic insulin secretion, and 86 Rb efflux were measured. INGAP-PP increased the expression levels of Kir6.2, SUR1 and Foxa2 genes, and SUR1 and Foxa2 proteins. INGAP-PP cultured islets released significantly more insulin in response to 40 mM KCl and 100 μM tolbutamide. INGAP-PP shifted to the left the dose-response curve of insulin secretion to increasing concentrations of glucose (EC 50 of 10.0 ± 0.4 vs. 13.7 ± 1.5 mM glucose of the controls). It also increased the first phase of insulin secretion elicited by either 22.2 mM glucose or 100 μM tolbutamide and accelerated the velocity of glucose-induced reduction of 86 Rb efflux in perifused islets. These effects were accompanied by a significant increase in [Ca 2+ ] i and the maintenance of a considerable degree of [Ca 2+ ] i oscillations. These results confirm that the enhancing effect of INGAP-PP upon insulin release, elicited by different secretagogues, is due to an improvement of the secretory function in cultured islets. Such improvement is due, at least partly, to an increased K + ATP channel protein expression and/or changing in the kinetic properties of these channels and augmented [Ca 2+ ] i response. Accordingly, INGAP-PP could potentially be used to maintain the functional integrity of cultured islets and eventually, for the prevention and treatment of diabetes. |
| Databáze: | OpenAIRE |
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