Masuda E S, Yamaguchi-Iwai Y, Tsuboi A, Hung P, Arai K, Arai N
Department of Cellular Biology, DNAX Research Institute, Palo Alto, CA 94304.
Biochem Biophys Res Commun. 1994 Dec 30;205(3):1518-25. doi: 10.1006/bbrc.1994.2839.
The cis-acting region, GM-kappa B/GC-box (positions -95 and -73), within the murine GM-CSF gene promoter is required for maximal induction by stimulation with phorbol-12-myristate acetate (PMA) and calcium ionophore (A23187) in T cells. GM-kappa B defines a binding site for NF-kappa B, and GC-box defines a binding site for three (A1, A2, B) constitutive proteins. We report here that three copies of the GC-box can functionally compensate for the GM-kappa B/GC-box region, suggesting that the GC-motif can function independently of the GM-kappa B motif. The major GC-box binding activity A1 was purified and identified as the transcription factor Sp1. We show that depletion of Sp1 (A1) from nuclear extracts specifically decreases in vitro transcription activity on GM-CSF templates. Since the human GM-CSF promoter has a base difference within the GC-box, we speculate that this may explain why the human promoter is weak and that an upstream enhancer is required for the induction of the human GM-CSF gene.
小鼠GM-CSF基因启动子内的顺式作用区域GM-κB/GC盒（位置-95和-73）是T细胞经佛波醇-12-肉豆蔻酸酯乙酸酯（PMA）和钙离子载体（A23187）刺激实现最大诱导所必需的。GM-κB定义了NF-κB的一个结合位点，而GC盒定义了三种（A1、A2、B）组成型蛋白的结合位点。我们在此报告，三个拷贝的GC盒可在功能上补偿GM-κB/GC盒区域，这表明GC基序可独立于GM-κB基序发挥作用。主要的GC盒结合活性A1被纯化并鉴定为转录因子Sp1。我们表明，从核提取物中去除Sp1（A1）会特异性降低GM-CSF模板的体外转录活性。由于人GM-CSF启动子在GC盒内存在碱基差异，我们推测这可能解释了为什么人启动子较弱，以及人GM-CSF基因的诱导需要一个上游增强子。
