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Targeted disruption of pancreatic-derived factor (PANDER, FAM3B) impairs pancreatic beta-cell function.

Robert-Cooperman CE, Carnegie JR, Wilson CG, Yang J, Cook JR, Wu J, Young RA, Wolf BA, Burkhardt BR - Diabetes (2010)

Bottom Line: Pancreatic-derived factor (PANDER, FAM3B) is a pancreatic islet-specific cytokine-like protein that is secreted from beta-cells upon glucose stimulation.Islet perifusion and calcium imaging studies showed abnormal responses of the PANDER(-/-) islets to glucose stimulation.Taken together, these results demonstrated decreased pancreatic beta-cell function in the PANDER(-/-) mouse.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology and Laboratory Medicine, The Children’s Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania, USA.

ABSTRACT

Objective: Pancreatic-derived factor (PANDER, FAM3B) is a pancreatic islet-specific cytokine-like protein that is secreted from beta-cells upon glucose stimulation. The biological function of PANDER is unknown, and to address this we generated and characterized a PANDER knockout mouse.

Research design and methods: To generate the PANDER knockout mouse, the PANDER gene was disrupted and its expression was inhibited by homologous recombination via replacement of the first two exons, secretion signal peptide and transcriptional start site, with the neomycin gene. PANDER(-/-) mice were then phenotyped by a number of in vitro and in vivo tests to evaluate potential effects on glucose regulation, insulin sensitivity, and beta-cell morphology and function.

Results: Glucose tolerance tests demonstrated significantly higher blood glucose levels in PANDER(-/-) versus wild-type male mice. To identify the mechanism of the glucose intolerance, insulin sensitivity and pancreatic beta-cell function were examined. Hyperinsulinemic-euglycemic clamps and insulin tolerance testing showed similar insulin sensitivity for both the PANDER(-/-) and wild-type mice. The in vivo insulin response following intraperitoneal glucose injection surprisingly produced significantly higher insulin levels in the PANDER(-/-) mice, whereas insulin release was blunted with arginine administration. Islet perifusion and calcium imaging studies showed abnormal responses of the PANDER(-/-) islets to glucose stimulation. In contrast, neither islet architecture nor insulin content was impacted by the loss of PANDER. Interestingly, the elevated insulin levels identified in vivo were attributed to decreased hepatic insulin clearance in the PANDER(-/-) islets. Taken together, these results demonstrated decreased pancreatic beta-cell function in the PANDER(-/-) mouse.

Conclusions: These results support a potential role of PANDER in the pancreatic beta-cell for regulation or facilitation of insulin secretion.

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Related in: MedlinePlus

Abnormal calcium response to glucose stimulation in PANDER−/− islets. Intracellular calcium concentration was determined via fura-2 fluorescence imaging during a glucose perifusion on isolated PANDER−/− and WT islets with stimulation from a glucose ramp and KCl (n = 3). Time of glucose increase is shown above and on the x-axis. Representative calcium plots are shown. Values are means ± SE.
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Figure 6: Abnormal calcium response to glucose stimulation in PANDER−/− islets. Intracellular calcium concentration was determined via fura-2 fluorescence imaging during a glucose perifusion on isolated PANDER−/− and WT islets with stimulation from a glucose ramp and KCl (n = 3). Time of glucose increase is shown above and on the x-axis. Representative calcium plots are shown. Values are means ± SE.

Mentions: The inhibited insulin secretion found in PANDER−/− islets did not appear to be based at the level of islet architecture, metabolic gene expression, or insulin content, and therefore suggested a potential disruption of glucose metabolism or generation of secondary signals required for initiating insulin exocytosis. To evaluate both glucose metabolism and generation of secondary signals, we measured the ATP-to-ADP ratio and intracellular Ca2+, respectively, from both PANDER−/− and wild-type isolated islets. At physiological glucose concentrations (2, 5, and 10 mmol/l), the ATP-to-ADP ratio in PANDER−/− islets was indistinguishable from that of wild-type islets (data not shown). These results suggest that glucose metabolism is maintained in PANDER−/− islets, and this was consistent with the maintenance of normal gene expression of the various metabolic genes of GLUT2 and glucokinase. For evaluation of secondary signals, changes in cytosolic Ca2+ during glucose and KCl stimulation were monitored by fura-2 fluorescence imaging (Fig. 6). The intracellular Ca2+ response in PANDER−/− islets differed from that in wild-type islets in the following ways: hyperresponse of calcium at the 3-mmol/l condition; lack of calcium dip attributed to SERCA (15,16) immediately preceeding the rapid rise in intracellular calcium at 16 mmol/l glucose that was observed in wild-type islets; modest descrease in overall amplitude following 16 mmol/l glucose; and decreased KCl response. However, both PANDER−/− and wild-type islets promptly returned to baseline after reaching the 0-mmol/l glucose condition. The abnormal calcium handling of PANDER−/− mouse islets may potentially indicate a mechanism for the impaired GSIS observed in vitro and glucose intolerance with blunted arginine response observed in vivo.


Targeted disruption of pancreatic-derived factor (PANDER, FAM3B) impairs pancreatic beta-cell function.

Robert-Cooperman CE, Carnegie JR, Wilson CG, Yang J, Cook JR, Wu J, Young RA, Wolf BA, Burkhardt BR - Diabetes (2010)

Abnormal calcium response to glucose stimulation in PANDER−/− islets. Intracellular calcium concentration was determined via fura-2 fluorescence imaging during a glucose perifusion on isolated PANDER−/− and WT islets with stimulation from a glucose ramp and KCl (n = 3). Time of glucose increase is shown above and on the x-axis. Representative calcium plots are shown. Values are means ± SE.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2927943&req=5

Figure 6: Abnormal calcium response to glucose stimulation in PANDER−/− islets. Intracellular calcium concentration was determined via fura-2 fluorescence imaging during a glucose perifusion on isolated PANDER−/− and WT islets with stimulation from a glucose ramp and KCl (n = 3). Time of glucose increase is shown above and on the x-axis. Representative calcium plots are shown. Values are means ± SE.
Mentions: The inhibited insulin secretion found in PANDER−/− islets did not appear to be based at the level of islet architecture, metabolic gene expression, or insulin content, and therefore suggested a potential disruption of glucose metabolism or generation of secondary signals required for initiating insulin exocytosis. To evaluate both glucose metabolism and generation of secondary signals, we measured the ATP-to-ADP ratio and intracellular Ca2+, respectively, from both PANDER−/− and wild-type isolated islets. At physiological glucose concentrations (2, 5, and 10 mmol/l), the ATP-to-ADP ratio in PANDER−/− islets was indistinguishable from that of wild-type islets (data not shown). These results suggest that glucose metabolism is maintained in PANDER−/− islets, and this was consistent with the maintenance of normal gene expression of the various metabolic genes of GLUT2 and glucokinase. For evaluation of secondary signals, changes in cytosolic Ca2+ during glucose and KCl stimulation were monitored by fura-2 fluorescence imaging (Fig. 6). The intracellular Ca2+ response in PANDER−/− islets differed from that in wild-type islets in the following ways: hyperresponse of calcium at the 3-mmol/l condition; lack of calcium dip attributed to SERCA (15,16) immediately preceeding the rapid rise in intracellular calcium at 16 mmol/l glucose that was observed in wild-type islets; modest descrease in overall amplitude following 16 mmol/l glucose; and decreased KCl response. However, both PANDER−/− and wild-type islets promptly returned to baseline after reaching the 0-mmol/l glucose condition. The abnormal calcium handling of PANDER−/− mouse islets may potentially indicate a mechanism for the impaired GSIS observed in vitro and glucose intolerance with blunted arginine response observed in vivo.

Bottom Line: Pancreatic-derived factor (PANDER, FAM3B) is a pancreatic islet-specific cytokine-like protein that is secreted from beta-cells upon glucose stimulation.Islet perifusion and calcium imaging studies showed abnormal responses of the PANDER(-/-) islets to glucose stimulation.Taken together, these results demonstrated decreased pancreatic beta-cell function in the PANDER(-/-) mouse.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology and Laboratory Medicine, The Children’s Hospital of Philadelphia Research Institute, Philadelphia, Pennsylvania, USA.

ABSTRACT

Objective: Pancreatic-derived factor (PANDER, FAM3B) is a pancreatic islet-specific cytokine-like protein that is secreted from beta-cells upon glucose stimulation. The biological function of PANDER is unknown, and to address this we generated and characterized a PANDER knockout mouse.

Research design and methods: To generate the PANDER knockout mouse, the PANDER gene was disrupted and its expression was inhibited by homologous recombination via replacement of the first two exons, secretion signal peptide and transcriptional start site, with the neomycin gene. PANDER(-/-) mice were then phenotyped by a number of in vitro and in vivo tests to evaluate potential effects on glucose regulation, insulin sensitivity, and beta-cell morphology and function.

Results: Glucose tolerance tests demonstrated significantly higher blood glucose levels in PANDER(-/-) versus wild-type male mice. To identify the mechanism of the glucose intolerance, insulin sensitivity and pancreatic beta-cell function were examined. Hyperinsulinemic-euglycemic clamps and insulin tolerance testing showed similar insulin sensitivity for both the PANDER(-/-) and wild-type mice. The in vivo insulin response following intraperitoneal glucose injection surprisingly produced significantly higher insulin levels in the PANDER(-/-) mice, whereas insulin release was blunted with arginine administration. Islet perifusion and calcium imaging studies showed abnormal responses of the PANDER(-/-) islets to glucose stimulation. In contrast, neither islet architecture nor insulin content was impacted by the loss of PANDER. Interestingly, the elevated insulin levels identified in vivo were attributed to decreased hepatic insulin clearance in the PANDER(-/-) islets. Taken together, these results demonstrated decreased pancreatic beta-cell function in the PANDER(-/-) mouse.

Conclusions: These results support a potential role of PANDER in the pancreatic beta-cell for regulation or facilitation of insulin secretion.

Show MeSH
Related in: MedlinePlus