Possible Involvement of Atypical Protein Kinase C(PKC) in Glucose-Sensitive Expression of the Human Insulin Gene: DNA-Binding Activity and Transcriptional Activity of Pancreatic and Duodenal Homeobox Gene-1(PDX-1) Are Enhanced via Calphostin C-Sensitive but Phorbol 12-Myristate 13-Acetate(PMA) and Goe 6976-Insensitive Pathway
| Autor: | Hiroyuki Motoshima, Kaku Tsuruzoe, Kengo Kaneko, Mikio Todaka, Noboru Furukawa, Kazuya Matsumoto, Tetsuya Shirotani, Motoaki Shichiri, Eiichi Araki, Kazuaki Yoshizato, Hideki Kishikawa |
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| Rok vydání: | 1999 |
| Předmět: |
Gene isoform
endocrine system Indoles Transcription Genetic Endocrinology Diabetes and Metabolism Carbazoles Gene Expression Naphthalenes Biology Transfection Cell Line Islets of Langerhans Mice chemistry.chemical_compound Endocrinology Animals Humans Insulin Electrophoretic mobility shift assay Calphostin Enzyme Inhibitors Phosphorylation Protein kinase A Protein Kinase C Protein kinase C Homeodomain Proteins Activator (genetics) DNA Molecular biology Phosphoric Monoester Hydrolases Glucose Calphostin C chemistry Trans-Activators Phorbol Tetradecanoylphorbol Acetate hormones hormone substitutes and hormone antagonists |
| Zdroj: | Endocrine Journal. 46:43-58 |
| ISSN: | 1348-4540 0918-8959 |
| DOI: | 10.1507/endocrj.46.43 |
| Popis: | Pancreatic and duodenal homeobox gene-1 (PDX-1) is a transcription factor which regulates the insulin gene expression. In this study, we tried to elucidate the role of PDX-1 in the glucose-induced transcriptional activation of the human insulin gene promoter in MIN6 cells. Electrophoretic mobility shift assay (EMSA) and chloramphenicol acetyltransferase (CAT) assay demonstrated that both DNA-binding activity and transcriptional activity of PDX-1 were increased with 20 mmol/l glucose more than with 2 mmol/l glucose. The DNA-binding activity of PDX-1 induced by high glucose was blocked by phosphatase treatment, suggesting the involvement of PDX-1 phosphorylation in this event. In an in vitro phosphorylation study, PDX-1 was phosphorylated by protein kinase C (PKC), but not by cAMP dependent protein kinase (PKA) or mitogen-activated protein kinase (MAPK). Furthermore, increased PDX-1 function induced by high glucose was blocked by calphostin C, an inhibitor of all PKC isoforms, but unaffected by phorbol 12-myristate 13-acetate (PMA), an activator of classical and novel PKC, or Gö 6976, an inhibitor of classical and novel PKC, which suggested that the PKC family which activated PDX-1 in MIN6 cells was atypical PKC. Western blot and immunocytochemical studies with anti-PKC zeta antibody confirmed the presence of PKC zeta, one of the isoforms of atypical PKC, in MIN6 cells. Furthermore, PKC zeta activity was significantly increased by glucose stimulation. These results suggest that high glucose increased DNA-binding activity of PDX-1 by activating atypical PKC including PKC zeta, resulting in transcriptional activation of the human insulin gene promoter. |
| Databáze: | OpenAIRE |
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