Lian Lingdan, Zhang Guang, Zhu Jing, Wang Yunxiao, Wang Lingshuai, Liu Rui, Shi Liang, Ren Ang, Zhao Mingwen
Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China.
College of Life Science and Technology, Henan Institute of Science and Technology, Xinxiang, 453003, China.
Environ Microbiol. 2021 Aug;23(8):4405-4417. doi: 10.1111/1462-2920.15627. Epub 2021 Jun 14.
The cell wall integrity (CWI) signaling activates the transcription factor Swi6 through a MAPK signaling cascade in response to cell wall stresses. In this study, we observed two different mRNA variants of swi6 (GlSwi6A and GlSwi6B) existed, due to alternative splicing. Besides, the expression level of GlSwi6B was higher than that of the GlSwi6A mRNA variant. The co-silencing of GlSwi6A and GlSwi6B was more sensitive to cell wall stress compared with WT, resulting in a decrease of 78% and 76% in chitin and β-1,3-d-glucan content respectively. However, only the overexpression of GlSwi6B decreased the sensitivity to cell wall stress and increased the content of chitin and β-1,3-d-glucan compared with the WT strain. Furthermore, Y1H, EMSA and BLI assays revealed that the GlSwi6B could bind to the promoters of chitin and glucan synthesis genes (GL24454 and GL18134). However, the binding phenome has not been observed in the isoform GlSwi6A. Taken together, our results found two different transcripts generated from Swi6, in which the alternative splice isoform of GlSwi6B participates in regulating the CWI of G. lucidum. This study provides the first insight into the alternative splicing isoform of GlSwi6B in the regulation of CWI signaling in fungi.
细胞壁完整性（CWI）信号传导通过丝裂原活化蛋白激酶（MAPK）信号级联反应激活转录因子Swi6，以响应细胞壁应激。在本研究中，我们观察到由于可变剪接，存在两种不同的swi6 mRNA变体（GlSwi6A和GlSwi6B）。此外，GlSwi6B的表达水平高于GlSwi6A mRNA变体。与野生型相比，GlSwi6A和GlSwi6B的共沉默对细胞壁应激更敏感，导致几丁质和β-1,3 -d-葡聚糖含量分别降低78%和76%。然而，与野生型菌株相比，只有GlSwi6B的过表达降低了对细胞壁应激的敏感性，并增加了几丁质和β-1,3 -d-葡聚糖的含量。此外，酵母单杂交（Y1H）、电泳迁移率变动分析（EMSA）和生物层干涉（BLI）分析表明，GlSwi6B可以与几丁质和葡聚糖合成基因（GL24454和GL18134）的启动子结合。然而，在异构体GlSwi6A中未观察到这种结合现象。综上所述，我们的结果发现Swi6产生了两种不同的转录本，其中GlSwi6B的可变剪接异构体参与调节灵芝的细胞壁完整性。本研究首次揭示了GlSwi6B的可变剪接异构体在真菌细胞壁完整性信号传导调节中的作用。
