Rosenberger S F, Bowden G T
Department of Radiation Oncology, The University of Arizona Health Sciences Center, Tucson 85724, USA.
Oncogene. 1996 Jun 6;12(11):2301-8.
The effects of the non-phorbol ester type tumor promoter okadaic acid, a serine-threonine phosphatase inhibitor, on activator protein 1 (AP-1) DNA binding activity were studied in papilloma producing 308 mouse keratinocytes. Okadaic acid increased AP-1 binding to a consensus TPA responsive element (TRE) within 2 h; maximum stimulation was observed at 6 h followed by a gradual decrease to basal levels within 24 h. Jun B, Jun D and Fos B proteins were identified as the major components of the AP-1 complex binding to the TRE element at 6 h. Inhibition of transcription with actinomycin D and inhibition of protein synthesis with cycloheximide abrogated the okadaic acid effect on AP-1 DNA binding, indicating that transcription and translation are required for okadaic acid increased TRE binding activity. Northern and Western blot analyses revealed a correlation between increased AP-1 binding activity and accumulation of jun B, jun D and fos B mRNAs and proteins. These data suggest increased AP-1 expression as principal mechanism of okadaic acid stimulated AP-1 activation in the mouse keratinocytes studied.
在可产生乳头瘤的308小鼠角质形成细胞中，研究了丝氨酸 - 苏氨酸磷酸酶抑制剂、非佛波酯型肿瘤启动子冈田酸对激活蛋白1（AP-1）DNA结合活性的影响。冈田酸在2小时内增加了AP-1与共有佛波酯应答元件（TRE）的结合；在6小时时观察到最大刺激，随后在24小时内逐渐降至基础水平。Jun B、Jun D和Fos B蛋白被确定为6小时时与TRE元件结合的AP-1复合物的主要成分。用放线菌素D抑制转录和用环己酰亚胺抑制蛋白质合成消除了冈田酸对AP-1 DNA结合的影响，表明转录和翻译是冈田酸增加TRE结合活性所必需的。Northern印迹和Western印迹分析揭示了AP-1结合活性增加与jun B、jun D和fos B mRNA及蛋白质积累之间的相关性。这些数据表明，在所研究的小鼠角质形成细胞中，AP-1表达增加是冈田酸刺激AP-1激活的主要机制。
