Mittelstadt P R, Ashwell J D
Laboratory of Immune Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-1152, USA.
Mol Cell Biol. 1998 Jul;18(7):3744-51. doi: 10.1128/MCB.18.7.3744.
Activation-induced transcriptional upregulation of the ligand for Fas (FasL) and the resulting apoptosis of Fas-bearing cells constitute essential steps in a host of normal and pathological processes. Here we describe an activation-inducible cis-acting regulatory element in the fasL promoter that is required for gene expression. Oligonucleotide competition and antibody supershift analyses identified two activation-induced DNA-binding species: Egr-1 (NGFI-A, krox-24, zif268, TIS-8), a transcription factor that has been implicated in growth, differentiation, and apoptosis; and Egr-3 (PILOT), a transcription factor of no previously known function. Activation-induced expression of Egr-3, like that of FasL, was inhibited by cyclosporin A, whereas expression of Egr-1 was unaffected. Transient expression of Egr-3 alone increased fasL promoter activity in a cyclosporin A-insensitive manner, whereas expression of Egr-1 had little effect. Moreover, endogenous fasL mRNA was induced in nonlymphoid cells by forced expression of Egr-3 in the absence of any other stimulus. These studies identify a critical Egr family-binding site in the fasL promoter and demonstrate that activation-induced Egr-3, but not Egr-1, directly upregulates fasL transcription in response to activating stimuli.
Fas配体（FasL）的激活诱导转录上调以及由此导致的Fas阳性细胞凋亡是许多正常和病理过程中的关键步骤。在此，我们描述了fasL启动子中一个基因表达所需的激活诱导顺式作用调控元件。寡核苷酸竞争和抗体超迁移分析确定了两种激活诱导的DNA结合蛋白：Egr-1（NGFI-A、krox-24、zif268、TIS-8），一种与生长、分化和凋亡有关的转录因子；以及Egr-3（PILOT），一种此前功能未知的转录因子。与FasL一样，Egr-3的激活诱导表达受到环孢素A的抑制，而Egr-1的表达不受影响。单独瞬时表达Egr-3以环孢素A不敏感的方式增加fasL启动子活性，而Egr-1的表达几乎没有影响。此外，在没有任何其他刺激的情况下，通过强制表达Egr-3可在非淋巴细胞中诱导内源性fasL mRNA。这些研究确定了fasL启动子中一个关键的Egr家族结合位点，并证明激活诱导的Egr-3而非Egr-1直接上调fasL转录以响应激活刺激。
