Boehmelt G, Walker A, Kabrun N, Mellitzer G, Beug H, Zenke M, Enrietto P J
Institute of Molecular Pathology (IMP), Vienna, Austria.
EMBO J. 1992 Dec;11(12):4641-52. doi: 10.1002/j.1460-2075.1992.tb05566.x.
We describe the construction of a v-rel estrogen receptor fusion protein (v-relER) which allows the regulation of v-rel oncoprotein activity by hormone. In the presence of estrogen, v-relER readily transformed primary chicken fibroblasts and bone marrow cells in vitro. In both cell types, v-rel-specific transformation was critically dependent on the presence of estrogen or the estrogen agonist 4-hydroxytamoxifen (OHT). Withdrawal of estrogen or application of an estrogen antagonist, ICI164,384 (ICI) caused a reversal of the transformed phenotype. We also demonstrate that the v-relER protein binds to NF-kappa B sites in an estrogen-dependent manner, thereby showing that sequence-specific DNA binding of v-relER is critical for the activation of its transforming capacity. In transient transfection experiments, we failed to demonstrate a clear repressor or activator function of the v-rel moiety in v-relER. However, in v-relER-transformed bone marrow cells, estrogen and OHT induced elevated mRNA levels of two cellular genes whose expression is constitutive and high in v-rel-transformed cells. These results suggest that v-rel might exert part of its activity as an activator of rel-responsive genes.
我们描述了一种v-rel雌激素受体融合蛋白（v-relER）的构建，该蛋白可通过激素调节v-rel癌蛋白的活性。在雌激素存在的情况下，v-relER在体外能轻易转化原代鸡成纤维细胞和骨髓细胞。在这两种细胞类型中，v-rel特异性转化严重依赖于雌激素或雌激素激动剂4-羟基他莫昔芬（OHT）的存在。去除雌激素或应用雌激素拮抗剂ICI164,384（ICI）会导致转化表型的逆转。我们还证明，v-relER蛋白以雌激素依赖的方式与NF-κB位点结合，从而表明v-relER的序列特异性DNA结合对于激活其转化能力至关重要。在瞬时转染实验中，我们未能证明v-relER中v-rel部分具有明确的抑制或激活功能。然而，在v-relER转化的骨髓细胞中，雌激素和OHT诱导了两个细胞基因的mRNA水平升高，这两个基因在v-rel转化的细胞中组成性高表达。这些结果表明，v-rel可能作为rel反应基因的激活剂发挥其部分活性。
