Reactive oxygen species generated by microbial NADPH oxidase NoxA regulate sexual development in Aspergillus nidulans
Reactive oxygen species generated by microbial NADPH oxidase NoxA regulate sexual development in Aspergillus nidulans
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DOI：
10.1046/j.1365-2958.2003.03800.x
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发表时间：
2003-11-01
影响因子：
3.6
通讯作者：
Aguirre, J
中科院分区：
文献类型：
--
作者：
Lara-Ortíz, T;Riveros-Rosas, H;Aguirre, J
NADPH氧化酶（Nox）是一种高级真核生物酶，专门用于产生活性氧（ROS）。最近在植物和动物中发现了Nox家族的新功能成员，这使得人们认识到ROS作为参与调节多种细胞过程（如防御、生长和信号传导）的信号的重要性日益增加。在这里，我们解决的作用，NADPH氧化酶产生的活性氧在丝状真菌构巢曲霉的生物学。我们的noxA基因的特点，并表明它编码一个新的NADPH氧化酶亚家族普遍存在于低等真核生物的成员。noxA的缺失特异性地阻断有性子实体（闭孔菌）的分化，而不影响菌丝生长或无性发育。因此，noxA基因在性发育过程中被诱导，在闭囊藻分化时达到峰值，并与壳细胞相关的过氧化氢酶过氧化物酶基因cpeA平行。这种表达模式是不依赖于转录因子SteA和StuA，这是必不可少的闭壳绦虫形成。相反，在DeltasakA无效突变体中，noxA依赖性早熟性发育与noxA去阻遏相关，将应激MAPK信号传导与ROS的调节产生联系起来。使用硝基四氮唑蓝（NBT）测定，以检测超氧化物，我们发现，hulle细胞和隐孢子虫的起始产生超氧化物的过程中抑制NADPH氧化酶抑制剂DPI和显着减少DeltanoxA突变体。此外，使用H（2）DCFDA，我们检测到H2O2和可能的其他ROS是以NoxA依赖的方式产生的，主要是在外壁中由闭突藻原始细胞产生。NoxA产生的ROS在A. nidulans的性分化和一个或两个noxA同源物在所有分析的丝状真菌中的存在表明，NADPH氧化酶产生的ROS在真菌生理学和分化中起重要作用。
NADPH oxidases (Nox) have been characterized as higher eukaryotic enzymes used deliberately to produce reactive oxygen species (ROS). The recent discovery of new functional members of the Nox family in plants and animals has led to the recognition of the increasing importance of ROS as signals involved in regulation of diverse cellular processes such as defence, growth and signalling. Here, we address the role of NADPH oxidase-generated ROS in the biology of the filamentous fungus Aspergillus nidulans. We characterize the noxA gene and show that it encodes a member of a novel NADPH oxidase subfamily ubiquitous in lower eukaryotes. Deletion of noxA specifically blocks differentiation of sexual fruit bodies (cleistothecia), without affecting hyphal growth or asexual development. Accordingly, the noxA gene is induced during sexual development, peaking at the time of cleistothecia differentiation and in parallel with the hulle cell-associated catalase peroxidase gene cpeA. This expression pattern is not dependent on transcription factors SteA and StuA, which are essential for cleistothecia formation. In contrast, noxA-dependent premature sexual development correlates with noxA derepression in DeltasakA null mutants, connecting stress MAPK signalling to the regulated production of ROS. Using a nitroblue tetrazolium (NBT) assay to detect superoxide, we found that hulle cells and cleistothecia initials produce superoxide in a process inhibited by NADPH oxidase inhibitor DPI and markedly reduced in DeltanoxA mutants. Furthermore, using H(2)DCFDA, we detected that H2O2 and possibly other ROS are generated in a NoxA-dependent fashion, mainly in the external walls from cleistothecia initials. The essential role of NoxA-generated ROS in A. nidulans sexual differentiation and the presence of one or two noxA homologues in all analysed filamentous fungi suggest that NADPH oxidase-generated ROS play important roles in fungal physiology and differentiation.