Transcriptomic profiling of Aspergillus flavus in response to 5-azacytidine
Transcriptomic profiling of Aspergillus flavus in response to 5-azacytidine
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黄曲霉对 5-氮杂胞苷反应的转录组分析
DOI：
10.1016/j.fgb.2013.04.007
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发表时间：
2013-07-01
影响因子：
3
通讯作者：
He, Zhu-Mei
中科院分区：
文献类型：
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作者：
Lin, Jian-Qing;Zhao, Xi-Xi;He, Zhu-Mei
黄曲霉（Aspergillus flavus）是一种常见的条件致病菌，能产生黄曲霉毒素（AF）等多种次级代谢产物。5-氮杂胞苷（5-AC）是核苷胞苷的衍生物，广泛用于表观遗传学和癌症生物学的研究，作为DNA甲基转移酶的灭活剂，也用于研究真菌的次级代谢。我们以前的研究表明，5-AC影响发育，抑制AF的产生。flavus和A.黄曲霉缺乏DNA甲基化。本研究利用RNA-seq技术探讨了5-AC对A.黄色的我们在5-AC处理后鉴定了240个显著差异表达（Q值< 0.05）的基因，包括分别在次级代谢物簇#27和#35中的两个骨架基因。这两个簇参与菌核的发育或存活。GO功能富集分析表明，这些差异表达基因主要涉及催化活性和蛋白水解功能。AF生物合成基因簇中大部分基因在A.在用5-AC处理后，黄曲霉没有显示出显著的变化，并且以低水平表达，并且该簇中的转录调节基因aflR和aflS相对于未用5-AC处理的样品没有显示出差异表达。我们发现，在5-AC处理后，编码蛋白桥VelB和LaeA的veA基因显著降低了黄曲霉中表达的转录本，而编码发育早期调节因子的brlA基因增加了其转录本。我们的数据支持一种模型，即5-AC通过抑制veA的表达来增加brlA的表达，通过抑制veA的表达和羧肽酶活性失调来增加AF的产生，从而阻止黄曲霉毒素体（囊泡）在AF形成中发挥其正常功能，从而影响发育。此外，抑制veA表达减弱甚至中断VelB和LaeA之间的联系，导致A中参与发育和次生代谢的基因表达模式失调。黄色的这项工作中提供的RNA-seq数据也用于改进黄曲霉基因组的注释。这项工作提供了对5-AC响应的黄曲霉转录组的全面看法，并支持真菌发育和次级代谢共调节的结论。(C)2013 Elsevier Inc. All rights reserved.
Aspergillus flavus is a common saprophyte and opportunistic pathogen producing aflatoxin (AF) and many other secondary metabolites. 5-Azacytidine (5-AC), a derivative of the nucleoside cytidine, is widely used for studies in epigenetics and cancer biology as an inactivator of DNA methyltransferase and is also used for studying secondary metabolism in fungi. Our previous studies showed that 5-AC affects development and inhibits AF production in A. flavus, and that A. flavus lacks DNA methylation. In this study, an RNA-seq approach was applied to explore the mechanism of 5-AC's effect on A. flavus. We identified 240 significantly differentially expressed (Q-value < 0.05) genes after 5-AC treatment, including two backbone genes respectively in secondary metabolite clusters #27 and #35. These two clusters are involved in development or survival of sclerotia. GO functional enrichment analysis showed that these significantly differentially expressed genes were mainly involved in catalytic activity and proteolytic functions. The expressed transcripts of most genes in the AF biosynthetic gene cluster in A. flavus showed no significant changes after treatment with 5-AC and were expressed at low levels, and the transcription regulator genes aflR and aflS in this cluster did not show differential expression relative to the sample without 5-AC treatment. We found that the veA gene, which encodes protein bridges VelB and LaeA, decreased profoundly the expressed transcripts, and brlA, which encodes an early regulator of development, increased its transcripts in A.flavus after 5-AC treatment. Our data support a model whereby 5-AC affects development through increasing the expression of brlA by depressing the expression of veA and AF production through suppressing veA expression and dysregulating carboxypeptidase activity, which then prevents the aflatoxisomes (vesicles) from performing their normal function in AF formation. Furthermore, the suppressed veA expression weakens or even interrupts the connection between VelB and LaeA, leading to dysregulation of the expression pattern of genes involved in development and secondary metabolism in A. flavus. The RNA-seq data presented in this work were also served to improve the annotation of the A.flavus genome. This work provides a comprehensive view of the transcriptome of A.flavus responsive to 5-AC and supports the conclusion that fungal development and secondary metabolism are co-regulated. (C) 2013 Elsevier Inc. All rights reserved.