Huang Ying, Song Jing, Soyano Kiyoshi, Ren Qian
College of Oceanography, Hohai University, 1 Xikang Road, Nanjing, Jiangsu, 210098, China.
Research Center of Aquatic Organism Conservation and Water Ecosystem Restoration in University of Anhui Province, College of Life Science, Anqing Normal University, 1318 Jixian North Road, Anqing, Anhui, 246133, China; Graduate School of Fisheries and Environmental Studies, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki, 852-8521, Japan; Institute for East China Sea Research, Organization for Marine Science and Technology, Nagasaki University, 1551-7 Taira-machi, Nagasaki, 851-2213, Japan.
Dev Comp Immunol. 2021 Jul;120:104068. doi: 10.1016/j.dci.2021.104068. Epub 2021 Mar 11.
Dorsal is a Rel/NF-κB transcription factor, which forms a key part of the Toll pathway. Lysozyme is a ubiquitous enzyme that degrades bacterial cell walls. In this study, a Dorsal homolog was cloned and characterized from triangle sail mussel Hyriopsis cumingii, namely, HcDorsal. Dorsal consisted of 3041 bp, including a 1938 bp open reading frame encoding a 645 amino acid protein. The deduced HcDorsal protein contained a Rel homology domain and an Ig-like, plexin, transcription factor domain. Analysis of expression patterns showed that HcDorsal was highly expressed in the hepatopancreas of H. cumingii. The expression level of HcDorsal continuously increased after Vibrio parahaemolyticus stimulation. When HcDorsal was knocked down by siRNA interference, two phage lysozyme genes (HcLyso1 and HcLyso2) obtained by horizontal gene transfer were significantly downregulated in hemocytes of mussels. Furthermore, knockdown of HcLyso1 and HcLyso2 could weaken V. parahaemolyticus clearance ability. Recombinant HcLyso1 and HcLyso2 proteins accelerated the bacterial clearance in vivo in mussels and evidently inhibited the growth of V. parahaemolyticus. These results suggested that HcDorsal could be activated after V. parahaemolyticus stimulation and then modulate the immune response through the transcriptional regulation of HcLyso1 and HcLyso2, thereby playing a protective role in mussels.
背侧蛋白是一种Rel/NF-κB转录因子，它构成了Toll信号通路的关键部分。溶菌酶是一种能降解细菌细胞壁的普遍存在的酶。在本研究中，从三角帆蚌中克隆并鉴定了一个背侧蛋白同源物，即HcDorsal。HcDorsal全长3041 bp，包含一个1938 bp的开放阅读框，编码一个645个氨基酸的蛋白质。推导的HcDorsal蛋白包含一个Rel同源结构域和一个免疫球蛋白样、丛状蛋白、转录因子结构域。表达模式分析表明，HcDorsal在三角帆蚌的肝胰腺中高表达。副溶血性弧菌刺激后，HcDorsal的表达水平持续升高。当通过siRNA干扰敲低HcDorsal时，通过水平基因转移获得的两个噬菌体溶菌酶基因（HcLyso1和HcLyso2）在蚌的血细胞中显著下调。此外，敲低HcLyso1和HcLyso2会削弱副溶血性弧菌的清除能力。重组HcLyso1和HcLyso2蛋白加速了蚌体内细菌的清除，并明显抑制了副溶血性弧菌的生长。这些结果表明，副溶血性弧菌刺激后HcDorsal可被激活，然后通过对HcLyso1和HcLyso2的转录调控来调节免疫反应，从而在蚌中发挥保护作用。
