Cooney A J, Hummelke G C, Herman T, Chen F, Jackson K J
Department of Cell Biology, Baylor College of Medicine, Houston, Texas, 77030, USA.
Biochem Biophys Res Commun. 1998 Apr 7;245(1):94-100. doi: 10.1006/bbrc.1998.8391.
We have shown that the orphan receptor Germ Cell Nuclear Factor (GCNF) binds to a direct repeat of the sequence AGGTCA with zero base pair spacing (DR0). Here, we further characterize the binding characteristics of GCNF. We demonstrate that GCNF binds specifically to DR0s as a homodimer, and does not bind with high affinity to DR1-DR6 sequences. GCNF is the first nuclear receptor shown to bind specifically to DR0s. The wild type GCNF is unable to transactivate the reporter plasmid DR0(2)tkCAT. Lacking a ligand to activate GCNF, we fused the activation domain from the viral protein VP16 to GCNF, and observed activation of DR0(2)tkCAT. This activation is specifc to DR0s, and is not observed when that sequence is replaced by DR1-DR6 sequences. In addition GCNF does not transactivate through an SF-1 response element. At increasing concentrations, wild type GCNF is able to repress basal transcription. Repression is again specific to DR0s. The preference of GCNF for the DR0 sequence both in vitro and in transfections suggests that GCNF defines a novel nuclear receptor signaling pathway.
我们已经证明，孤儿受体生殖细胞核因子（GCNF）可与序列AGGTCA的直接重复序列结合，间隔为零碱基对（DR0）。在此，我们进一步表征GCNF的结合特性。我们证明GCNF作为同二聚体特异性结合DR0，而不与DR1 - DR6序列高亲和力结合。GCNF是首个被证明特异性结合DR0的核受体。野生型GCNF无法激活报告质粒DR0(2)tkCAT。由于缺乏激活GCNF的配体，我们将病毒蛋白VP16的激活结构域与GCNF融合，并观察到DR0(2)tkCAT的激活。这种激活对DR0具有特异性，当该序列被DR1 - DR6序列取代时则未观察到激活。此外，GCNF不会通过SF - 1反应元件激活转录。随着浓度增加，野生型GCNF能够抑制基础转录。抑制同样对DR0具有特异性。GCNF在体外和转染实验中对DR0序列的偏好表明，GCNF定义了一条新的核受体信号通路。
