Ernest Gallo Research Center, Department of Neurology, University of California, San Francisco, Emeryville, California 94608.
Cell Biology Laboratory, Department of Biochemistry, BioSciences Institute, University College Cork, Cork, Ireland.
J Biol Chem. 2012 Jan 2;287(1):322-336. doi: 10.1074/jbc.M111.272195. Epub 2011 Nov 8.
RACK1 is a scaffolding protein that spatially and temporally regulates numerous signaling cascades. We previously found that activation of the cAMP signaling pathway induces the translocation of RACK1 to the nucleus. We further showed that nuclear RACK1 is required to promote the transcription of the brain-derived neurotrophic factor (BDNF). Here, we set out to elucidate the mechanism underlying cAMP-dependent RACK1 nuclear translocation and BDNF transcription. We identified the scaffolding protein 14-3-3ζ as a direct binding partner of RACK1. Moreover, we found that 14-3-3ζ was necessary for the cAMP-dependent translocation of RACK1 to the nucleus. We further observed that the disruption of RACK1/14-3-3ζ interaction with a peptide derived from the RACK1/14-3-3ζ binding site or shRNA-mediated 14-3-3ζ knockdown inhibited cAMP induction of BDNF transcription. Together, these data reveal that the function of nuclear RACK1 is mediated through its interaction with 14-3-3ζ. As RACK1 and 14-3-3ζ are two multifunctional scaffolding proteins that coordinate a wide variety of signaling events, their interaction is likely to regulate other essential cellular functions.
RACK1 是一种支架蛋白，可以在空间和时间上调节许多信号级联反应。我们之前发现，cAMP 信号通路的激活会诱导 RACK1 向核内易位。我们进一步表明，核内 RACK1 是促进脑源性神经营养因子（BDNF）转录所必需的。在这里，我们着手阐明 cAMP 依赖性 RACK1 核易位和 BDNF 转录的机制。我们确定了支架蛋白 14-3-3ζ 是 RACK1 的直接结合伴侣。此外，我们发现 14-3-3ζ 对于 RACK1 依赖 cAMP 的核易位是必需的。我们进一步观察到，用源自 RACK1/14-3-3ζ 结合位点的肽或 shRNA 介导的 14-3-3ζ 敲低破坏 RACK1/14-3-3ζ 相互作用会抑制 cAMP 诱导的 BDNF 转录。总之，这些数据表明核内 RACK1 的功能是通过与 14-3-3ζ 的相互作用介导的。由于 RACK1 和 14-3-3ζ 是两种多功能支架蛋白，它们可以协调各种信号事件，因此它们的相互作用可能调节其他重要的细胞功能。
