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Submitted on January 24, 2007
Accepted on October 15, 2007
-cells
Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School of the Chinese Academy of Sciences, Shanghai, P. R. China
* To whom correspondence should be addressed. E-mail: yyle{at}sibs.ac.cn.
Pancreatic-derived factor (PANDER) is a cytokine-like peptide highly expressed in pancreatic
-cells. PANDER was reported to promote apoptosis of pancreatic
-cells and secrete in response to glucose. Here we explored the effects of glucose on PANDER expression and the underlying mechanisms in murine pancreatic
-cell line MIN6 and primary islets. Our results showed that glucose upregulated PANDER mRNA and protein levels in time- and dose-dependent manner in MIN6 cells and pancreatic islets. In cells expressing CREB dominant-negative construct, glucose failed to induce PANDER gene expression and promoter activation. Treatment of the cells with calcium chelator (EGTA, BAPTA/AM), the voltage-dependent Ca2+ channel inhibitor (nifedipine), the PKA inhibitor (H89), the PKC inhibitor (Go6976), or the MEK1/2 inhibitor (PD98059), all significantly inhibited glucose-induced PANDER gene expression and promoter activation. Further studies showed that glucose induced CREB phosphorylation through Ca2+-PKA-ERK1/2 and Ca2+-PKC pathways. Thus, the Ca2+-PKA-ERK1/2-CREB and Ca2+-PKC-CREB signaling pathways are involved in glucose-induced PANDER gene expression. Wortmannin (PI3K inhibitor), PDTC (NF-
B inhibitor and nonspecific antioxidant), and N-acetylcysteine (antioxidant) were also found to inhibit glucose-induced PANDER promoter activation and gene expression. As there is no NF-
B binding site in the promoter region of PANDER gene, these results suggest that PI3K and reactive oxygen species be involved in glucose-induced PANDER gene expression. In conclusion, glucose induces PANDER gene expression in pancreatic
-cells through multiple signaling pathways. As PANDER is expressed by pancreatic
-cells and in response to glucose in a similar way to those of insulin, PANDER may be involved in glucose homeostasis.
-cell
glucose
gene expression
signal transduction
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