Characterisation of functional inhibition of the glucocorticoid receptor by Fos/Jun.
Characterisation of functional inhibition of the glucocorticoid receptor by Fos/Jun.
复制标题
Fos/Jun 对糖皮质激素受体功能抑制的表征。
作者：
M. Touray;F. Ryan;R. Jaggi;F. Martin
我们研究了Fos和Fos/Jun对糖皮质激素诱导的糖皮质激素敏感基因表达的影响。在NIH 3 T3细胞中，通过转染pSV 2-fos和pSV 2-jun，过表达Fos或Fos/Jun，抑制糖皮质激素依赖的MMTV LTR-CAT的表达。p39 v-mos的表达对糖皮质激素依赖的报告基因表达有类似的影响，这很可能是通过刺激内源性Fos介导的。在这两种情况下，这种抑制可以克服糖皮质激素受体（GR）从瞬时转染的表达载体的过表达。在受体缺陷型CV-1细胞中，糖皮质激素依赖性报告基因的表达由一系列功能性GR截短突变体诱导。它被确定为C/D结构域的受体是一个足够的目标Fos和Fos/Jun的抑制。C/D结构域包括的GR的DNA结合域，二聚化结构域和弱transactivational结构域。当同时存在于细胞核中的Fos和Jun被证明形成一个特定的和稳定的蛋白质/蛋白质复合物与糖皮质激素受体。最后，它被证明，GR物理相互作用与Fos和Jun同时在体外共翻译时。我们认为这种相互作用可能是Fos或Fos/Jun抑制GR功能的机制。
We have studied the effects of Fos and Fos/Jun on glucocorticoid induction of hormone-sensitive gene expression. In NIH3T3 cells overexpression of Fos or Fos/Jun by transfection of pSV2-fos and pSV2-jun inhibited glucocorticoid-dependent expression of MMTV LTR-CAT. Expression of p39v-mos had a similar effect on glucocorticoid-dependent reporter gene expression which is most likely mediated by simulation of endogenous Fos. In both cases, this inhibition could be overcome by overexpression of the glucocorticoid receptor (GR) from a transiently transfected expression vector. In receptor deficient CV-1 cells glucocorticoid-dependent reporter gene expression was induced by a range of functional GR truncation mutants. It was established that the C/D domain of the receptor was a sufficient target for inhibition by Fos and Fos/Jun. The C/D domain encompasses the DNA-binding domain, a dimerisation domain and a weak transactivational domain of the GR. When present simultaneously in the cell nucleus Fos and Jun were shown to form a specific and stable protein/protein complex with the glucocorticoid receptor. Finally, it was demonstrated that the GR interacts physically with both Fos and Jun when cotranslated simultaneously in vitro. We propose that this interaction may be the mechanism by which Fos or Fos/Jun bring about inhibition of GR function.