Imhof M O, McDonnell D P
Department of Pharmacology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Mol Cell Biol. 1996 Jun;16(6):2594-605. doi: 10.1128/MCB.16.6.2594.
We have developed a system in Saccharomyces cerevisiae in which agonist-dependent transcriptional activity of the human progesterone receptor (hPR) is elevated to the point that it compromises cell growth. Screens for suppressors of this phenotype led to the demonstration that RSP5 is involved in hPR transactivation. Expression of RSP5 in yeast cells potentiated hPR and human glucocorticoid receptor (hGR) transcriptional activity and increased the efficacy of weak agonists of these receptors. Remarkably, expression of this yeast protein in mammalian cells had a similar effect on PR and GR transcriptional activity. Importantly, a human homolog of RSP5, hRPF1, functioned identically in mammalian cells. Previously, it has been demonstrated that RSP5 overexpression in yeast cells suppressed mutations within SPT3, a protein which interacts with the TATA-box-binding protein (TBP), suggesting that RSP5 and SPT3 operate in the same regulatory pathway. In support of this observation, we have shown that SPT3 enhances the activity of RSP5 on GR and PR when tested in yeast or mammalian cells. We conclude from these experiments that the regulatory pathways in which RSP5 and SPT3 operate in yeast cells are conserved in higher eukaryotes. Additionally, since SPT3 has been shown to contact yeast TBP directly and is the likely homolog of human TBP-associated factor TAFII18, we propose that RSP5/hRPF1 and SPT3 establish a functional link between activated PR and GR and the general transcription apparatus.
我们在酿酒酵母中开发了一个系统，在该系统中，人孕酮受体（hPR）的激动剂依赖性转录活性被提高到损害细胞生长的程度。对这种表型的抑制子进行筛选，结果表明RSP5参与hPR的反式激活。在酵母细胞中表达RSP5可增强hPR和人糖皮质激素受体（hGR）的转录活性，并提高这些受体的弱激动剂的效力。值得注意的是，在哺乳动物细胞中表达这种酵母蛋白对PR和GR的转录活性有类似的影响。重要的是，RSP5的人类同源物hRPF1在哺乳动物细胞中的功能相同。以前已经证明，在酵母细胞中过表达RSP5可抑制SPT3内的突变，SPT3是一种与TATA盒结合蛋白（TBP）相互作用的蛋白质，这表明RSP5和SPT3在相同的调节途径中发挥作用。为支持这一观察结果，我们已经表明，在酵母或哺乳动物细胞中进行测试时，SPT3可增强RSP5对GR和PR的活性。我们从这些实验中得出结论，RSP5和SPT3在酵母细胞中发挥作用的调节途径在高等真核生物中是保守的。此外，由于已证明SPT3直接与酵母TBP接触，并且可能是人类TBP相关因子TAFII18的同源物，我们提出RSP5/hRPF1和SPT3在活化的PR和GR与通用转录装置之间建立了功能联系。
