Levi B Z, Kasik J W, Burke P A, Prywes R, Roeder R G, Appella E, Ozato K
Laboratory of Developmental and Molecular Immunity, National Institute of Child Health and Human Development, Bethesda, MD 20892.
Proc Natl Acad Sci U S A. 1989 Apr;86(7):2262-6. doi: 10.1073/pnas.86.7.2262.
The expression of the c-fos gene is transiently induced at birth in most organs in the mouse. To study the basis of this induction we searched for a nuclear factor that binds to the 5' regulatory region of the c-fos gene. Gel mobility shift assays with tissue extracts revealed fast (band I) and slow (band III) migrating bands, which represent factor binding to the c-fos enhancer, termed the serum response element (SRE). Neonatal extracts preferentially elicited band I, with low or undetectable levels of band III, whereas fetal and adult extracts generated predominantly band III, with reduced levels of band I. These results indicate that the SRE-binding activity changes during perinatal development and that the appearance of band I, which coincides with diminution of band III, correlates with neonatal c-fos induction. Methylation interference and competition analyses showed that the neonatal factor (band I) binds to the SRE at a site different from the adult factor (band III). DNA-binding activity of the adult factor, but not the neonatal factor, was sensitive to phosphatase treatment. Furthermore, the adult factor, but not the neonatal factor, shared antigenic specificity with the human serum response factor (SRF) that is expressed in cultured cells irrespective of c-fos gene induction. We conclude that band I in neonates represents a SRE-binding factor that is distinct from the SRF, which may be responsible for the neonatal induction of the c-fos gene. The band III factor was indistinguishable from the SRF in all criteria tested.
c-fos基因的表达在小鼠出生时于大多数器官中被短暂诱导。为了研究这种诱导的基础，我们寻找了一种与c-fos基因5'调控区结合的核因子。用组织提取物进行的凝胶迁移率变动分析显示出快速迁移带（带I）和慢速迁移带（带III），它们代表与c-fos增强子结合的因子，该增强子被称为血清反应元件（SRE）。新生动物提取物优先产生带I，带III水平低或检测不到，而胎儿和成年动物提取物主要产生带III，带I水平降低。这些结果表明，SRE结合活性在围产期发育过程中发生变化，并且与带III减少同时出现的带I的出现与新生动物c-fos的诱导相关。甲基化干扰和竞争分析表明，新生动物因子（带I）与SRE的结合位点不同于成年动物因子（带III）。成年动物因子而非新生动物因子的DNA结合活性对磷酸酶处理敏感。此外，成年动物因子而非新生动物因子与在培养细胞中表达的人血清反应因子（SRF）具有抗原特异性，而与c-fos基因诱导无关。我们得出结论，新生动物中的带I代表一种与SRF不同的SRE结合因子，它可能是c-fos基因新生动物诱导的原因。在所有测试标准中，带III因子与SRF无法区分。
