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Y. Xia, E. Geh, M. Mongan, A. Puga; Molecular Regulation of MAP3K1 Expression. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3077. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Mitogen-activated protein kinase kinase kinase 1 (MAP3K1) is involved in eyelid closure during mouse embryonic development. MAP3K1 is highly expressed in the leading edge of the eyelid epithelium just prior to the onset of eyelid closure and its ablation in mice results in defective eyelid morphogenesis. We hypothesize that the induction of MAP3K1 expression is critical for embryonic eyelid closure. The purpose of this study is to investigate the molecular mechanisms that regulate MAP3K1 expression.
Bioinformatics (PROSCAN) was used to predict the promoter region of mouse Map3k1. A DNA fragment, 1900 bp upstream of the transcription start site of Map3k1 encompassing the predicted promoter sequences, was isolated using polymerase chain reaction and cloned into pGL3, a promoter-less expression vector, containing a luciferase (Luc) reporter gene (p1900Map3k1-Luc). The exogenous promoter activities were analyzed in HEK293 cells following transient transfection and measuring luciferase activity. For endogenous MAP3K1 promoter activity, we isolated mouse embryonic fibroblasts (MEFs) from the Map3k1ΔKD fetuses, in which a β-galactosidase gene was knocked in the Map3k1 locus and thus β-gal expression was under the control of the Map3k1 promoter. These cells were used to study the induction of Map3k1 promoter activity following various treatments by measuring β-galactosidase activity.
TGF-α, TGF-β, activin B and taxol had no effect on the Map3k1 promoter activities in the Map3k1ΔKD MEFs and p1900 Map3k1-Luc transfected 293 cells; however, colchicine and nocodazole, both microtubule disrupting agents, caused a 2-3-fold induction. Additionally, histone deacetylace (HDAC) inhibitors, sodium butyrate and trichostatin A, strongly induced the Map3k1 promoter activities up to 16-fold. Colchicine and HDAC inhibitors together exhibited a cumulative effect on the induction of the Map3k1 promoter.
The Map3k1 promoter activity is regulated through at least two mechanisms. One is histone aceytlation and another is microtubule disruption. The later is possibly mediated through cytoskeleton re-organization and transcription factor activation.
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