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ABSTRACT: Background
Choline kinase is the most upstream enzyme in the CDP-choline pathway. It catalyzes the phosphorylation of choline to phosphorylcholine in the presence of ATP and Mg2+ during the biosynthesis of phosphatidylcholine, the major phospholipid in eukaryotic cell membranes. In humans, choline kinase (CK) is encoded by two separate genes, ck? and ck?, which produce three isoforms, CK?1, CK?2, and CK?. Previous studies have associated ck? with muscle development; however, the molecular mechanism underlying the transcriptional regulation of ck? has never been elucidated.Methodology/principal findings
In this report, the distal promoter region of the ck? gene was characterized. Mutational analysis of the promoter sequence and electrophoretic mobility shift assays (EMSA) showed that Ets and GATA transcription factors were essential for the repression of ck? promoter activity. Supershift and chromatin immunoprecipitation (ChIP) assays further identified that GATA3 but not GATA2 was bound to the GATA site of ck? promoter. In addition, phorbol-12-myristate-13-acetate (PMA) decreased ck? promoter activity through Ets and GATA elements. PMA also decreased the ck? mRNA and protein levels about 12 hours after the promoter activity was down-regulated. EMSA further revealed that PMA treatment increased the binding of both Ets and GATA transcription factors to their respective DNA elements. The PMA-mediated repressive effect was abolished by chronic PMA treatment and by treatment with the PKC inhibitor PKC412, but not the PKC inhibitor Go 6983, suggesting PKC? or PKC? as the PKC isozyme involved in the PMA-mediated repression of ck? promoter. Further confirmation by using PKC isozyme specific inhibitors identified PKC? as the isozyme that mediated the PMA repression of ck? promoter.Conclusion/significance
These results demonstrate the participation of the PKC signaling pathway in the regulation of ck? gene transcription by Ets and GATA transcription factors.
SUBMITTER: Kuan CS
PROVIDER: S-EPMC4260826 | biostudies-literature | 2014
REPOSITORIES: biostudies-literature
PloS one 20141209 12
<h4>Background</h4>Choline kinase is the most upstream enzyme in the CDP-choline pathway. It catalyzes the phosphorylation of choline to phosphorylcholine in the presence of ATP and Mg2+ during the biosynthesis of phosphatidylcholine, the major phospholipid in eukaryotic cell membranes. In humans, choline kinase (CK) is encoded by two separate genes, ckα and ckβ, which produce three isoforms, CKα1, CKα2, and CKβ. Previous studies have associated ckβ with muscle development; however, the molecula ...[more]