Exendin-4 regulates GLUT2 expression via the CaMKK/CaMKIV pathway in a pancreatic β-cell line

Ke Chen, Xiao Yu, Koji Murao, Hitomi Imachi, Junhua Li, Tomie Muraoka, Hisashi Masugata, Guo Xing Zhang, Ryoji Kobayashi, Toshihiko Ishida, Hiroshi Tokumitsu

Research output: Contribution to journalArticle

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Abstract

The GLUT2 glucose transporter plays an important role in glucose-induced insulin secretion in pancreatic β-cells by catalyzing the uptake of glucose into the cell. In this study, we investigated whether exendin-4, a long-acting agonist of glucagon-like peptide-1, mediates stimulatory effects on GLUT2 gene expression through the Ca2+/calmodulin (CaM)-dependent protein kinase IV (CaMKIV) cascade. GLUT2 expression was examined by real-time polymerase chain reaction, Western blot analysis, and a reporter gene assay in rat insulin-secreting INS-1 cells incubated with exendin-4. An increased expression level of GLUT2 protein was noted in response to increasing concentrations of exendin-4, with maximal induction at 10 nmol/L. Real-time polymerase chain reaction analysis similarly revealed a significant increase in the amount of GLUT2 messenger RNA by 10 nmol/L exendin-4. Exendin-4 also stimulated GLUT2 promoter activity in response to increasing exendin-4 concentrations, but failed to do so in the presence of STO-609, a CaMKK inhibitor. We also investigated the effect of the constitutively active form of CaMKK (CaMKKc) on GLUT2 promoter activity. The result is consistent with the observations that CaMKKc/CaMKIV enhanced or up-regulated GLUT2 promoter activity in INS-1 cells. Furthermore, exendin-4 induction of GLUT2 protein expression was significantly suppressed in the cells knocking down the CaMKIV. In summary, activation of the CaMKK/CaMKIV cascade might be required for exendin-4-induced GLUT2 gene transcription, indicating that exendin-4 plays an important role in insulin secretion in pancreatic β-cells.

Original languageEnglish
Pages (from-to)579-585
Number of pages7
JournalMetabolism: Clinical and Experimental
Volume60
Issue number4
DOIs
Publication statusPublished - Apr 2011
Externally publishedYes

Fingerprint

Calcium-Calmodulin-Dependent Protein Kinase Kinase
Protein Kinases
Cell Line
Glucose Transporter Type 2
Insulin
Real-Time Polymerase Chain Reaction
Calcium-Calmodulin-Dependent Protein Kinase Type 4
exenatide
Glucose
Glucagon-Like Peptide 1
Facilitative Glucose Transport Proteins
Reporter Genes
Western Blotting

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Exendin-4 regulates GLUT2 expression via the CaMKK/CaMKIV pathway in a pancreatic β-cell line. / Chen, Ke; Yu, Xiao; Murao, Koji; Imachi, Hitomi; Li, Junhua; Muraoka, Tomie; Masugata, Hisashi; Zhang, Guo Xing; Kobayashi, Ryoji; Ishida, Toshihiko; Tokumitsu, Hiroshi.

In: Metabolism: Clinical and Experimental, Vol. 60, No. 4, 04.2011, p. 579-585.

Research output: Contribution to journalArticle

Chen, K, Yu, X, Murao, K, Imachi, H, Li, J, Muraoka, T, Masugata, H, Zhang, GX, Kobayashi, R, Ishida, T & Tokumitsu, H 2011, 'Exendin-4 regulates GLUT2 expression via the CaMKK/CaMKIV pathway in a pancreatic β-cell line', Metabolism: Clinical and Experimental, vol. 60, no. 4, pp. 579-585. https://doi.org/10.1016/j.metabol.2010.06.002
Chen, Ke ; Yu, Xiao ; Murao, Koji ; Imachi, Hitomi ; Li, Junhua ; Muraoka, Tomie ; Masugata, Hisashi ; Zhang, Guo Xing ; Kobayashi, Ryoji ; Ishida, Toshihiko ; Tokumitsu, Hiroshi. / Exendin-4 regulates GLUT2 expression via the CaMKK/CaMKIV pathway in a pancreatic β-cell line. In: Metabolism: Clinical and Experimental. 2011 ; Vol. 60, No. 4. pp. 579-585.
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AU - Yu, Xiao

AU - Murao, Koji

AU - Imachi, Hitomi

AU - Li, Junhua

AU - Muraoka, Tomie

AU - Masugata, Hisashi

AU - Zhang, Guo Xing

AU - Kobayashi, Ryoji

AU - Ishida, Toshihiko

AU - Tokumitsu, Hiroshi

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N2 - The GLUT2 glucose transporter plays an important role in glucose-induced insulin secretion in pancreatic β-cells by catalyzing the uptake of glucose into the cell. In this study, we investigated whether exendin-4, a long-acting agonist of glucagon-like peptide-1, mediates stimulatory effects on GLUT2 gene expression through the Ca2+/calmodulin (CaM)-dependent protein kinase IV (CaMKIV) cascade. GLUT2 expression was examined by real-time polymerase chain reaction, Western blot analysis, and a reporter gene assay in rat insulin-secreting INS-1 cells incubated with exendin-4. An increased expression level of GLUT2 protein was noted in response to increasing concentrations of exendin-4, with maximal induction at 10 nmol/L. Real-time polymerase chain reaction analysis similarly revealed a significant increase in the amount of GLUT2 messenger RNA by 10 nmol/L exendin-4. Exendin-4 also stimulated GLUT2 promoter activity in response to increasing exendin-4 concentrations, but failed to do so in the presence of STO-609, a CaMKK inhibitor. We also investigated the effect of the constitutively active form of CaMKK (CaMKKc) on GLUT2 promoter activity. The result is consistent with the observations that CaMKKc/CaMKIV enhanced or up-regulated GLUT2 promoter activity in INS-1 cells. Furthermore, exendin-4 induction of GLUT2 protein expression was significantly suppressed in the cells knocking down the CaMKIV. In summary, activation of the CaMKK/CaMKIV cascade might be required for exendin-4-induced GLUT2 gene transcription, indicating that exendin-4 plays an important role in insulin secretion in pancreatic β-cells.

AB - The GLUT2 glucose transporter plays an important role in glucose-induced insulin secretion in pancreatic β-cells by catalyzing the uptake of glucose into the cell. In this study, we investigated whether exendin-4, a long-acting agonist of glucagon-like peptide-1, mediates stimulatory effects on GLUT2 gene expression through the Ca2+/calmodulin (CaM)-dependent protein kinase IV (CaMKIV) cascade. GLUT2 expression was examined by real-time polymerase chain reaction, Western blot analysis, and a reporter gene assay in rat insulin-secreting INS-1 cells incubated with exendin-4. An increased expression level of GLUT2 protein was noted in response to increasing concentrations of exendin-4, with maximal induction at 10 nmol/L. Real-time polymerase chain reaction analysis similarly revealed a significant increase in the amount of GLUT2 messenger RNA by 10 nmol/L exendin-4. Exendin-4 also stimulated GLUT2 promoter activity in response to increasing exendin-4 concentrations, but failed to do so in the presence of STO-609, a CaMKK inhibitor. We also investigated the effect of the constitutively active form of CaMKK (CaMKKc) on GLUT2 promoter activity. The result is consistent with the observations that CaMKKc/CaMKIV enhanced or up-regulated GLUT2 promoter activity in INS-1 cells. Furthermore, exendin-4 induction of GLUT2 protein expression was significantly suppressed in the cells knocking down the CaMKIV. In summary, activation of the CaMKK/CaMKIV cascade might be required for exendin-4-induced GLUT2 gene transcription, indicating that exendin-4 plays an important role in insulin secretion in pancreatic β-cells.

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