Apyrase (Nucleoside Triphosphate-Diphosphohydrolase) and Extracellular Nucleotides Regulate Cotton Fiber Elongation in Cultured Ovules
Apyrase (Nucleoside Triphosphate-Diphosphohydrolase) and Extracellular Nucleotides Regulate Cotton Fiber Elongation in Cultured Ovules
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DOI：
10.1104/pp.109.147637
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发表时间：
2010-02-01
期刊：
影响因子：
7.4
通讯作者：
Roux, Stanley J.
中科院分区：
文献类型：
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作者：
Clark, Greg;Torres, Jonathan;Roux, Stanley J.
外腺苷三磷酸双磷酸酶从细胞外核苷三磷酸和核苷二磷酸中除去末端磷酸。在拟南芥（Arabidopsis thaliana）中，两种外腺苷三磷酸双磷酸酶AtAPY 1和AtAPY 2被认为是生长的关键调节剂。在棉花纤维中，当纤维进入快速生长期时，GhAPY 1和GhAPY 2的转录水平上调，GhAPY 1和GhAPY 2是两种与AtAPY 1和AtAPY 2具有高度序列相似性的密切相关的胞外三磷酸腺苷双磷酸酶。在胚珠培养系统中，纤维在生长时释放ATP，并且当通过添加多克隆抗腺苷三磷酸双磷酸酶抗体或通过两种不同的小分子抑制剂阻断其外腺苷三磷酸双磷酸酶活性时，培养基ATP水平升高并且纤维生长受到抑制。高浓度的难水解核苷酸ATP γ S和ADP β S应用于培养基抑制纤维生长，低浓度的它们刺激生长，但用腺苷5 '-O-硫代单磷酸处理不会引起生长速率的变化。应用核苷酸对生长的抑制和刺激都可以被阻断动物细胞中嘌呤受体的拮抗剂和腺苷阻断。用ATP γ S处理棉花胚珠培养物可诱导乙烯水平增加，两种乙烯拮抗剂，氨基乙烯基甘氨酸和硝酸银，可阻断应用核苷酸的生长刺激和生长抑制作用。此外，乙烯前体1-氨基环丙烷-1-羧酸降低了促进纤维生长所需的核苷酸浓度。这些数据表明，胞外腺苷三磷酸双磷酸酶和胞外核苷酸在调节棉纤维生长中起着重要作用，乙烯可能是信号通路的下游组分。
Ectoapyrase enzymes remove the terminal phosphate from extracellular nucleoside tri- and diphosphates. In Arabidopsis (Arabidopsis thaliana), two ectoapyrases, AtAPY1 and AtAPY2, have been implicated as key modulators of growth. In fibers of cotton (Gossypium hirsutum), transcript levels for GhAPY1 and GhAPY2, two closely related ectoapyrases that have high sequence similarity to AtAPY1 and AtAPY2, are up-regulated when fibers enter their rapid growth phase. In an ovule culture system, fibers release ATP as they grow, and when their ectoapyrase activity is blocked by the addition of polyclonal anti-apyrase antibodies or by two different small molecule inhibitors, the medium ATP level rises and fiber growth is suppressed. High concentrations of the poorly hydrolyzable nucleotides ATP gamma S and ADP beta S applied to the medium inhibit fiber growth, and low concentrations of them stimulate growth, but treatment with adenosine 5'-O-thiomonophosphate causes no change in the growth rate. Both the inhibition and stimulation of growth by applied nucleotides can be blocked by an antagonist that blocks purinoceptors in animal cells, and by adenosine. Treatment of cotton ovule cultures with ATP gamma S induces increased levels of ethylene, and two ethylene antagonists, aminovinylglycine and silver nitrate, block both the growth stimulatory and growth inhibitory effects of applied nucleotides. In addition, the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid, lowers the concentration of nucleotide needed to promote fiber growth. These data indicate that ectoapyrases and extracellular nucleotides play a significant role in regulating cotton fiber growth and that ethylene is a likely downstream component of the signaling pathway.