Sakai Yumiko, Sugano Shigeo S, Kawase Takashi, Shirakawa Makoto, Imai Yu, Kawamoto Yusuke, Sugiyama Hiroshi, Nakagawa Tsuyoshi, Hara-Nishimura Ikuko, Shimada Tomoo
Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan.
Development. 2017 Feb 1;144(3):499-506. doi: 10.1242/dev.145458. Epub 2017 Jan 13.
Stem cell polarization is a crucial step in asymmetric cell division, which is a universal system for generating cellular diversity in multicellular organisms. Several conventional genetics studies have attempted to elucidate the mechanisms underlying cell polarization in plants, but it remains largely unknown. In plants, stomata, which are valves for gas exchange, are generated through several rounds of asymmetric divisions. In this study, we identified and characterized a chemical compound that affects stomatal stem cell polarity. High-throughput screening for bioactive molecules identified a pyridine-thiazole derivative, named bubblin, which induced stomatal clustering in Arabidopsis epidermis. Bubblin perturbed stomatal asymmetric division, resulting in the generation of two identical daughter cells. Both cells continued to express the stomatal fate determinant SPEECHLESS, and then differentiated into mispatterned stomata. Bubblin-treated cells had a defect in the polarized localization of BREAKING OF ASYMMETRY IN THE STOMATAL LINEAGE (BASL), which is required for asymmetric cell fate determination. Our results suggest that bubblin induces stomatal lineage cells to divide without BASL-dependent pre-mitotic establishment of polarity. Bubblin is a potentially valuable tool for investigating cell polarity establishment in stomatal asymmetric division.
干细胞极化是不对称细胞分裂中的关键步骤，不对称细胞分裂是多细胞生物中产生细胞多样性的普遍系统。一些传统遗传学研究试图阐明植物细胞极化的潜在机制，但在很大程度上仍不清楚。在植物中，作为气体交换阀门的气孔是通过几轮不对称分裂产生的。在本研究中，我们鉴定并表征了一种影响气孔干细胞极性的化合物。对生物活性分子的高通量筛选鉴定出一种吡啶 - 噻唑衍生物，名为bubblin，它在拟南芥表皮中诱导气孔聚集。Bubblin扰乱了气孔不对称分裂，导致产生两个相同的子细胞。这两个细胞继续表达气孔命运决定因子SPEECHLESS，然后分化为排列错误的气孔。用Bubblin处理的细胞在气孔谱系不对称性打破（BASL）的极化定位方面存在缺陷，而BASL是不对称细胞命运决定所必需的。我们的结果表明，bubblin诱导气孔谱系细胞在没有依赖BASL的有丝分裂前极性建立的情况下进行分裂。Bubblin是研究气孔不对称分裂中细胞极性建立的潜在有价值的工具。
