Abstract
A number of factors have been reported to affect insulin synthesis in β-cells. Although glucose is the most important regulator of insulin gene expression in pancreatic β-cells, the mechanisms whereby glucose stimulates insulin gene transcription in response to changes in glucose concentration have not been clarified yet. In this study, we examined the role of the Ca2+/calmodulin (CaM)-dependent protein kinase (CaM-K) cascade in transcriptional activation of insulin. RT-PCR, Western blotting, and immunohistochemical staining analysis revealed that CaM-K kinase-α (CaM-KKα) and CaM-KIV were localized in rat pancreatic β-cells and their cell line, INS-1. Exposure of INS-1 cells to 11.2 mmol/l glucose elicited an increase of insulin promoter activity as well as upregulation of CaM-KIV activity within 2 min after stimulation. We investigated the influence on insulin promoter activity of the constitutively active form (CaM-KIVc) or dominant-negative mutant (CaM-KIVdn) of CaM-KIV in transfected INS-1 cells. CaM-KIVc alone was sufficient, and the upstream kinase, CaM-KK, was enhanced to upregulate the insulin promoter activity in INS-1 cells. Furthermore, cotransfection of CaM-KIVdn suppressed to a significant degree the glucose-upregulated activity of the insulin promoter. Taken together, these results indicated that the CaM-KK/CaM-KIV cascade might play an important role in glucose-upregulated transcriptional activation of the insulin gene.
| Original language | English |
|---|---|
| Pages (from-to) | 1475-1481 |
| Number of pages | 7 |
| Journal | Diabetes |
| Volume | 53 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - Jun 2004 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Internal Medicine
- Endocrinology, Diabetes and Metabolism
Cite this
The role of calcium/calmodulin-dependent protein kinase cascade in glucose upregulation of insulin gene expression. / Yu, Xiao; Murao, Koji; Sayo, Yoshitaka; Imachi, Hitomi; Cao, Wen M.; Ohtsuka, Shouji; Niimi, Michio; Tokumitsu, Hiroshi; Inuzuka, Hiroyuki; Wong, Norman C W; Kobayashi, Ryoji; Ishida, Toshihiko.
In: Diabetes, Vol. 53, No. 6, 06.2004, p. 1475-1481.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The role of calcium/calmodulin-dependent protein kinase cascade in glucose upregulation of insulin gene expression
AU - Yu, Xiao
AU - Murao, Koji
AU - Sayo, Yoshitaka
AU - Imachi, Hitomi
AU - Cao, Wen M.
AU - Ohtsuka, Shouji
AU - Niimi, Michio
AU - Tokumitsu, Hiroshi
AU - Inuzuka, Hiroyuki
AU - Wong, Norman C W
AU - Kobayashi, Ryoji
AU - Ishida, Toshihiko
PY - 2004/6
Y1 - 2004/6
N2 - A number of factors have been reported to affect insulin synthesis in β-cells. Although glucose is the most important regulator of insulin gene expression in pancreatic β-cells, the mechanisms whereby glucose stimulates insulin gene transcription in response to changes in glucose concentration have not been clarified yet. In this study, we examined the role of the Ca2+/calmodulin (CaM)-dependent protein kinase (CaM-K) cascade in transcriptional activation of insulin. RT-PCR, Western blotting, and immunohistochemical staining analysis revealed that CaM-K kinase-α (CaM-KKα) and CaM-KIV were localized in rat pancreatic β-cells and their cell line, INS-1. Exposure of INS-1 cells to 11.2 mmol/l glucose elicited an increase of insulin promoter activity as well as upregulation of CaM-KIV activity within 2 min after stimulation. We investigated the influence on insulin promoter activity of the constitutively active form (CaM-KIVc) or dominant-negative mutant (CaM-KIVdn) of CaM-KIV in transfected INS-1 cells. CaM-KIVc alone was sufficient, and the upstream kinase, CaM-KK, was enhanced to upregulate the insulin promoter activity in INS-1 cells. Furthermore, cotransfection of CaM-KIVdn suppressed to a significant degree the glucose-upregulated activity of the insulin promoter. Taken together, these results indicated that the CaM-KK/CaM-KIV cascade might play an important role in glucose-upregulated transcriptional activation of the insulin gene.
AB - A number of factors have been reported to affect insulin synthesis in β-cells. Although glucose is the most important regulator of insulin gene expression in pancreatic β-cells, the mechanisms whereby glucose stimulates insulin gene transcription in response to changes in glucose concentration have not been clarified yet. In this study, we examined the role of the Ca2+/calmodulin (CaM)-dependent protein kinase (CaM-K) cascade in transcriptional activation of insulin. RT-PCR, Western blotting, and immunohistochemical staining analysis revealed that CaM-K kinase-α (CaM-KKα) and CaM-KIV were localized in rat pancreatic β-cells and their cell line, INS-1. Exposure of INS-1 cells to 11.2 mmol/l glucose elicited an increase of insulin promoter activity as well as upregulation of CaM-KIV activity within 2 min after stimulation. We investigated the influence on insulin promoter activity of the constitutively active form (CaM-KIVc) or dominant-negative mutant (CaM-KIVdn) of CaM-KIV in transfected INS-1 cells. CaM-KIVc alone was sufficient, and the upstream kinase, CaM-KK, was enhanced to upregulate the insulin promoter activity in INS-1 cells. Furthermore, cotransfection of CaM-KIVdn suppressed to a significant degree the glucose-upregulated activity of the insulin promoter. Taken together, these results indicated that the CaM-KK/CaM-KIV cascade might play an important role in glucose-upregulated transcriptional activation of the insulin gene.
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UR - http://www.scopus.com/inward/citedby.url?scp=2542555198&partnerID=8YFLogxK
U2 - 10.2337/diabetes.53.6.1475
DO - 10.2337/diabetes.53.6.1475
M3 - Article
VL - 53
SP - 1475
EP - 1481
JO - Diabetes
JF - Diabetes
SN - 0012-1797
IS - 6
ER -