Horn S, Pfister H, Fuchs P G
Institut für Klinische und Molekulare Virologie, Friedrich-Alexander Universität, Erlangen-Nürnberg, Germany.
Virology. 1993 Oct;196(2):674-81. doi: 10.1006/viro.1993.1524.
Human papillomavirus (HPV) 8 belongs to the HPV types frequently associated with skin cancers of Epidermodysplasia verruciformis (EV)-patients. There are 33 nucleotides (M33 motif) in the 5'-part of the non-coding regulatory region of HPV8, which appear highly conserved among EV-specific HPVs and are consistently followed by an AP1 binding site. These sequences were shown to constitute an essential activator of transcription driven by the HPV8 late promoter P7535. The M33/AP1 element displayed properties of a constitutive enhancer, being also able to stimulate the activity of the heterologous thymidine kinase promoter in a position-independent manner. No protein binding could be detected within the 5'-part of the M33/AP1 region, which contributed significantly to the overall activity of the HPV8 enhancer. As shown by DNasel-footprinting, the central and the 3'-part of the enhancer region were involved in interactions with nuclear proteins. Three specific complexes could be observed in gel retardation tests with nuclear extracts from epithelial cells. One of these interactions involved the AP1 protein. Analysis of deletion and point mutations revealed binding of the AP1 protein to be essential for transcriptional activation, but DNA-protein interactions within M33 were important for maximal stimulation. The response to the phorbol ester TPA also required a cooperation of M33 and AP1.
人乳头瘤病毒（HPV）8属于经常与疣状表皮发育不良（EV）患者的皮肤癌相关的HPV类型。HPV8非编码调控区5'部分有33个核苷酸（M33基序），在EV特异性HPV中高度保守，且其后面始终跟着一个AP1结合位点。这些序列被证明构成了由HPV8晚期启动子P7535驱动的转录的必需激活因子。M33/AP1元件表现出组成型增强子的特性，也能够以位置独立的方式刺激异源胸苷激酶启动子的活性。在M33/AP1区域的5'部分未检测到蛋白质结合，这对HPV8增强子的整体活性有显著贡献。如DNA酶足迹法所示，增强子区域的中部和3'部分参与了与核蛋白的相互作用。在用上皮细胞核提取物进行的凝胶阻滞试验中可观察到三种特异性复合物。其中一种相互作用涉及AP1蛋白。缺失和点突变分析表明，AP1蛋白的结合对于转录激活至关重要，但M33内的DNA-蛋白质相互作用对于最大刺激很重要。对佛波酯TPA的反应也需要M33和AP1的协同作用。
