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INS-1 Cells (ins-1 + cell)
Selected AbstractsExendin-4 regulates pancreatic ABCA1 transcription via CaMKK/CaMKIV pathwayJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 5 2010Junhua Li Abstract ATP-binding cassette transporter A1 (ABCA1) in pancreatic , cells influences insulin secretion and glucose homeostasis. This study investigates whether the long-acting agonist of the glucagon-like peptide 1, namely exendin-4, which mediates stimulatory effects on ABCA1 gene expression, could interfere with the Ca2+/calmodulin (CaM)-dependent protein kinase (CaMK) cascade. ABCA1 promoter activity was examined by reporter gene assay in rat insulin-secreting INS-1 cells incubated with exendin-4. CaMKIV activity was assessed by detection of activation-loop phosphorylation (Thr196) of CaMKIV. We investigated the influence of the constitutively active form (CaMKIVc) or CaMKIV knockdown on ABCA1 expression. Increased abundance of ABCA1 protein was noted in response to rising concentrations of exendin-4 with maximum induction at 10 nM. Exendin-4 also stimulated ABCA1 promoter activity, but failed to do so in the presence of STO-609, a CaMKK inhibitor. Up-regulation of CaMKIV phosphorylation (at Thr196) peaked after 10 min. of exposure to exendin-4. CaMKIVc enhanced or up-regulated ABCA1 promoter activity in INS-1 cells. Furthermore, exendin-4 induction of ABCA1 protein expression was significantly suppressed in cells treated with CaMKIV-siRNA. Activation of the CaMKK/CaMKIV cascade by exendin-4 stimulated ABCA1 gene transcription, indicating that exendin-4 plays an important role in insulin secretion and cholesterol ester content in pancreatic , cells. [source] Shifts in metabolic parameters surrounding glucose homoeostasis resulting from tricyclic antidepressant therapy: implications of insulin resistance?JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 1 2007W. Chadwick This study displayed the physiological effects the tricyclic antidepressants amitriptyline or trimipramine have on glucose homoeostasis in male Wistar rats. An insulin secreting cell line (INS-1) was also used to determine effects tricyclic antidepressants have on insulin secretion and insulin displacement. Thirty rats each received a 1 mg kg,1 dose of amitriptyline or trimipramine for a period of 14 weeks; another 14 rats served as the control group. Blood glucose, serum insulin and muscle and liver glycogen levels were determined. Kidney, liver and muscle insulin degradation was measured and compared with insulin degrading enzyme concentrations in the latter two tissues. INS-1 cells were used to determine the effect 1,M amitriptyline has on insulin secretion. Displacement studies for [3H]glibenclamide by amitriptyline or trimipramine were undertaken on INS-1 cells. A significant increase in blood glucose (P < 0.01) was found for both test groups after 6 and 14 weeks of receiving the medication, which may be related to a significant decrease in liver and muscle glycogen levels (P < 0.001). Serum insulin levels remained unchanged, although a significant increase in insulin degradation was observed in the muscle, liver and kidney, which may be related to a significant increase in insulin degrading enzyme (P < 0.001) that was found. A significant increase in insulin secretion was observed for the INS-1 cells treated with amitriptyline, although no significant displacement for the [3H]glibenclamide was evident for amitriptyline or trimipramine. The significant alterations in glucose homoeostasis observed, as well as the significant changes associated with insulin secretion and degradation associated with amitriptyline or trimipramine treatment, imply that prolonged use of these medicines may lead to insulin resistance and full blown diabetes. [source] The effect of medicinal plants of Islamabad and Murree region of Pakistan on insulin secretion from INS-1 cellsPHYTOTHERAPY RESEARCH, Issue 1 2004Zakir Hussain Abstract In vitro testing of the extracts of medicinal plants collected from Islamabad and the Murree region on insulin secretagogue activity was carried out. Dried ethanol extracts of all plants (ZH1-ZH19) were dissolved in ethanol and DMSO, and tested at various concentrations (between 1 and 40 µg/mL) for insulin release from INS-1 cells in the presence of 5.5 mM glucose. Glibenclamide was used as a control. Promising insulin secretagogue activity in various plant extracts at 1, 10, 20 and 40 µg/mL was found, while in some cases a decrease in insulin secretion was also observed. Artemisia roxburghiana, Salvia coccinia and Monstera deliciosa showed insulin secretagogue activity at 1 µg/mL (p < 0.05) while Abies pindrow, Centaurea iberica and Euphorbia helioscopia were active at 10 µg/mL (p < 0.05). Extracts of Bauhinia variegata and Bergenia himalacia showed effects at 20 µg/mL (p < 0.05), and Taraxacum of,cinale and Viburnum foetens at 40 µg/mL (p < 0.05). Insulin secretagogue activity could not be detected in the extracts of Adhatoda vasica, Cassia ,stula, Chrysanthemum leucanthemum, Morus alba, Plectranthus rugosus, Peganum harmala and Olea ferruginea. The results suggest that medicinal plants of Islamabad and the Murree region of Pakistan may be potential natural resources for antidiabetic compounds. Copyright © 2004 John Wiley & Sons, Ltd. [source] Hemoglobin regulates the metabolic and synthetic function of rat insulinoma cells cultured in a hollow fiber bioreactorBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2010Sharon I. Gundersen Abstract Pancreatic islet transplantation continues to benefit patients with type 1 diabetes by normalizing glucose metabolism and improving other complications of diabetes. However, islet transplantation therapy is limited by the inadequate availability of pancreatic islets. In order to address this concern, this work investigated the expansion of rat insulinoma cells (INS-1) and their ability to generate insulin in a hollow fiber bioreactor (HFB). The long-term goal of this project is to develop a bioartificial pancreas. HFBs were incubated at two different oxygenation conditions (10% and 19% O2) to determine the best scenario for O2 transport to cultured cells. Also, bovine hemoglobin (BvHb) was supplemented in the cell culture media of the HFBs in order to increase O2 transport under both oxygenation conditions. Our results show that INS-1 cells expanded under all oxygenation conditions after 2 weeks of culture, with a slightly higher cell expansion under normoxic oxygenation (19% O2) for both control HFBs and BvHb HFBs. In addition, cellular insulin production remained steady throughout the study for normoxic control HFBs and BvHb HFBs, while it increased under hypoxic oxygenation (10% O2) for both types of HFBs but to different extents. Under the two different oxygenation conditions, cellular insulin production was more uniform with time in BvHb HFBs versus control HFBs. These results, along with qRT-PCR analysis, suggest a possible dysregulation of the insulin-signaling pathway under hypoxic culture conditions. In conclusion, the HFB culture system is an environment capable of expanding insulinomas while maintaining their viability and insulin production capabilities. Biotechnol. Bioeng. 2010;107: 582,592. © 2010 Wiley Periodicals, Inc. [source] Modulation of insulin release by adenosine A1 receptor agonists and antagonists in INS-1 cells: The possible contribution of 86Rb+ efflux and 45Ca2+ uptakeCELL BIOCHEMISTRY AND FUNCTION, Issue 8 2008M. Töpfer Abstract Due to the lack of specific agonists and antagonists the role of adenosine receptor subtypes with respect to their effect on the insulin secretory system is not well investigated. The A1 receptor may be linked to different 2nd messenger systems, i.e. cAMP, K+ - and 45Ca2+ channel activity. Partial A1 receptor agonists are going to be developed in order to improve diabetes (increase in insulin sensitivity, lowering of FFA and triglycerides). In this study newly synthesized selective A1 receptor agonists and antagonists were investigated thereby integrating three parameters, insulin release (RIA), 45Ca2+ uptake and 86Rb+ efflux (surrogate for K+ efflux) of INS-1 cells, an insulin secretory cell line. The presence of A1 -receptors was demonstrated by Western blotting. The receptor nonselective adenosine analogue NECA (5,- N -ethylcarboxyamidoadenosine) at high concentration (10,µM) had no effect on insulin release and 45Ca2+ uptake which could be interpreted as the sum of effects mediated by mutual antagonistic adenosine receptor subtypes. However, an inhibitory effect mediated by A1 receptor agonism was detected at 10,nM NECA and could be confirmed by adding the A1 receptor antagonist PSB-36 (1-butyl-8-(3-noradamantyl)-3-(3-hydroxy-propyl)xanthine). NECA inhibited 86Rb+ efflux which, however, did not fit with the simultaneous inhibition of insulin secretion. The selective A1 receptor agonist CHA (N6 -cyclohexyladenosine) inhibited insulin release; the simultaneously increased Ca2+ uptake (nifedipine dependent) and inhibition of 86Rb+ efflux did not fit the insulin release data. The CHA effect (even the maximum effect at 50,µM) can be increased by 10,µM NECA indicating that CHA and NECA have nonspecific and physiologically non-relevant effects on 86Rb+ efflux in addition to their A1 -receptor interaction. Since PSB-36 did not influence the NECA-induced inhibition of 86Rb+ efflux, the NECA effect is not mediated by potassium channel-linked A1 receptors. The nonselective adenosine receptor antagonist caffeine increased insulin release which was reversed by CHA as expected when hypothesizing that both act via A1 receptors in this case. In conclusion, stimulation of A1 receptors by receptor selective and nonselective compounds reduced insulin release which is not coupled to opening of potassium channels (86Rb+ efflux experiments) or inhibition of calcium channels (45Ca2+ uptake experiments). It may be expected that of all pleiotropic 2nd messengers, the cAMP system (not tested here) is predominant for A1 receptor effects and the channel systems (K+ and Ca2+) are of minor importance and do not contribute to insulin release though being coupled to the receptor in other tissues. Copyright © 2008 John Wiley & Sons, Ltd. [source] Effects of retinoids and thiazolidinediones on proliferation, insulin release, insulin mRNA, GLUT 2 transporter protein and mRNA of INS-1 cellsCELL BIOCHEMISTRY AND FUNCTION, Issue 3 2001J. Blumentrath Abstract Both 9-cis-retinoic acid (9cRA) and all-trans-retinoic acid (ATRA) are active metabolites of vitamin A (retinol). There exists an interaction between retinoid receptors and peroxisome proliferator-activated receptors (PPAR,). To define their functions in an insulin secreting system the effects of ATRA, 9cRA and the PPAR, agonist rosiglitazone on cell proliferation, insulin release and glucose transporter (GLUT) 2 of INS-1 cells were tested. Retinoic acid receptor (RAR-, and -,) and retinoid X receptor (RXR-, and -,) proteins are present (immunoblots). Both 9cRA and ATRA inhibit INS-1 cell proliferation ([3H]-thymidine assay) in a concentration dependent manner. Both 9cRA and ATRA increased insulin release, but only ATRA ralsed the GLUT 2 mRNA in a bell-shaped concentration response curve after 48,h. The insulinotropic effect of one compound is not significantly superimposed by the other indicating that the same binding sites are used by 9cRA and ATRA. The acute and chronic effects of the PPAR, agonist rosiglitazone on insulin release were additionally determined since glitazones act as transcription factors together with RXR agonists. At high concentrations (100,,m) rosiglitazone inhibited glucose (8.3,mm) stimulated insulin secretion (acute experiment over 60,min). Insulin secretion, however, was increased during a 24,h treatment at a concentration of 10,,m and again inhibited at 100,,m. Changes in preproinsulin mRNA expression were not observed. Rosiglitazone (100,,m) increased GLUT 2 mRNA paralleled by an increase of GLUT 2 protein, but only after 24,h of treatment. This data indicate that RAR and RXR mediate insulin release. The changes in GLUT 2 have no direct impact on insulin release; the inhibition seen at high concentrations of either compound is possibly the result of the observed inhibition of cell proliferation. Effects of rosiglitazone on preproinsulin mRNA and GLUT 2 (mRNA and protein) do not play a role in modulating insulin secretion. With the presence of an RXR receptor agonist the effect of rosiglitazone on insulin release becomes stimulatory. Thus the effects of RAR-, RXR agonists and rosiglitazone depend on their concentrations, the duration of their presence and are due to specific interactions. Copyright © 2001 John Wiley & Sons, Ltd. [source] | |||||||||||||