Department of Ecology, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, P. R. China.
Department of Plant Nutrition, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, P. R. China.
Mol Plant. 2017 May 1;10(5):695-708. doi: 10.1016/j.molp.2017.01.010. Epub 2017 Feb 5.
To control gene expression by directly responding to hormone concentrations, both animal and plant cells have exploited comparable mechanisms to sense small-molecule hormones in nucleus. Whether nuclear entry of these hormones is actively transported or passively diffused, as conventionally postulated, through the nuclear pore complex, remains enigmatic. Here, we identified and characterized a jasmonate transporter in Arabidopsis thaliana, AtJAT1/AtABCG16, which exhibits an unexpected dual localization at the nuclear envelope and plasma membrane. We show that AtJAT1/AtABCG16 controls the cytoplasmic and nuclear partition of jasmonate phytohormones by mediating both cellular efflux of jasmonic acid (JA) and nuclear influx of jasmonoyl-isoleucine (JA-Ile), and is essential for maintaining a critical nuclear JA-Ile concentration to activate JA signaling. These results illustrate that transporter-mediated nuclear entry of small hormone molecules is a new mechanism to regulate nuclear hormone signaling. Our findings provide an avenue to develop pharmaceutical agents targeting the nuclear entry of small molecules.
为了通过直接响应激素浓度来控制基因表达，动物和植物细胞都利用了类似的机制来感知细胞核中的小分子激素。这些激素是通过核孔复合体主动运输还是被动扩散进入细胞核，这一传统假设仍然是个谜。在这里，我们鉴定并表征了拟南芥中的茉莉酸（jasmonate）转运蛋白 AtJAT1/AtABCG16，它表现出出乎意料的双重定位，即在核膜和质膜上。我们表明，AtJAT1/AtABCG16 通过介导茉莉酸（JA）的细胞外排和茉莉酰异亮氨酸（JA-Ile）的核内流入，控制茉莉酸植物激素的细胞质和核分区，并且对于维持激活 JA 信号所需的关键核 JA-Ile 浓度是必不可少的。这些结果表明，转运蛋白介导的小分子激素的核内进入是一种新的调节核激素信号的机制。我们的发现为开发针对小分子核内进入的药物制剂提供了一个途径。
