Department of Pharmaco-Biology, Laboratory of Biochemistry and Molecular Biology, University of Bari, Bari, Italy.
Biochem Biophys Res Commun. 2011 Jan 7;404(1):376-81. doi: 10.1016/j.bbrc.2010.11.126. Epub 2010 Dec 3.
This study investigates the transcriptional role of the human mitochondrial carnitine/acylcarnitine carrier (CAC) proximal promoter. Through deletion analysis, an activation domain (-334/-80 bp) was identified which contains FOXA and Sp1 active sites. The wild-type (but not mutated) -334/-80 bp region of the CAC gene conferred 74% LUC transgene activity in HepG2 cells, 17% in HEK293 cells and 14% in SK-N-SH cells as compared to that observed with the entire -1503/+3 bp proximal promoter. Overexpression and silencing of FOXA2 or Sp1 in HepG2 cells enhanced and diminished, respectively, LUC activity, CAC transcript and CAC protein. In HEK293 and SK-N-SH cells, which do not contain FOXA1-3, LUC activity was increased by FOXA2 overexpression to a greater extent than in HepG2 cells. Both FOXA2 and Sp1 in HepG2, and only Sp1 in HEK293 and SK-N-SH cells, were found to be bound to the CAC proximal promoter. These results show that FOXA and Sp1 sites in HepG2 cells and only the Sp1 site in HEK293 and SK-N-SH cells have a critical role in the transcriptional regulation of the CAC proximal promoter.
本研究探讨了人线粒体肉碱/酰基辅酶 A 载体 (CAC) 近端启动子的转录作用。通过缺失分析，确定了一个激活域 (-334/-80 bp)，其中包含 FOXA 和 Sp1 活性位点。与整个 -1503/+3 bp 近端启动子相比，CAC 基因的野生型 (-334/-80 bp 区域在 HepG2 细胞中赋予 74% 的 LUC 转基因活性，在 HEK293 细胞中为 17%，在 SK-N-SH 细胞中为 14%。与野生型相比，FOXA2 或 Sp1 的过表达和沉默分别增强和减弱了 HepG2 细胞中的 LUC 活性、CAC 转录本和 CAC 蛋白。在不包含 FOXA1-3 的 HEK293 和 SK-N-SH 细胞中，FOXA2 的过表达使 LUC 活性的增加程度大于 HepG2 细胞。FOXA2 和 Sp1 在 HepG2 细胞中，而仅 Sp1 在 HEK293 和 SK-N-SH 细胞中，均被发现与 CAC 近端启动子结合。这些结果表明，FOXA 和 Sp1 位点在 HepG2 细胞中以及仅 Sp1 位点在 HEK293 和 SK-N-SH 细胞中在 CAC 近端启动子的转录调控中具有关键作用。
