Fishery College, Guangdong Ocean University, Zhanjiang, 524025, China; Guangdong Technology Research Center for pearl aquaculture and process, Zhanjiang, 524025, China.
Fishery College, Guangdong Ocean University, Zhanjiang, 524025, China.
Fish Shellfish Immunol. 2020 Apr;99:322-330. doi: 10.1016/j.fsi.2020.02.018. Epub 2020 Feb 12.
Myeloid differentiation factor 88 (MyD88) is an adapter protein that links toll-like receptor and interleukin 1 receptor-mediated signal transduction. In this study, we identified 20 MyD88 genes from eight mollusk genomes and found that MyD88 was expanded in bivalves. This expansion tends to be tandem duplication. Phylogenetic analysis suggested that the tandem duplication of MyD88 was formed before bivalve differentiation. All of the identified MyD88 contained both of death domain (DD) and toll/interleukin-1 receptor (TIR) domain, and 13 mollusks MyD88 have low complexity regions (LCRs), which were not found in the MyD88 from humans and zebrafish. The genomic structure showed that most of the mollusk MyD88 (14 of 19) contained five conserved introns, four of which were found in humans and zebrafish. Furthermore, the cDNA full length of PfmMyD88-2 (one of the two identified MyD88 in Pincatada fucata martensii) was obtained with 1591 bp, including 260 bp of 5'UTR, 257 bp of 3'UTR, and 1077 bp of open reading frame encoding 358 amino acids. Quantitative real-time PCR analysis demonstrated that PfmMyD88-2 mRNA was widely expressed in all detected tissues. The highest expression level was in the gills and followed by hepatopancreas and feet. After lipopolysaccharide stimulation, PfmMyD88-2 expression level increased and reached the highest level at 12 h and then gradually declined to the normal level. Over-expression of PfmMyD88-2 in HEK293T increased the luciferase activity of the pNF-κB-Luc reporter. We also identified that PfmmiR-4047 could regulate the expression of PfmMyD88-2. These results help us elucidate the mechanism underlying mollusk immune response.
髓样分化因子 88（MyD88）是一种衔接蛋白，可连接 Toll 样受体和白细胞介素 1 受体介导的信号转导。本研究从 8 种软体动物基因组中鉴定了 20 个 MyD88 基因，发现 MyD88 在双壳类动物中扩张。这种扩张倾向于串联重复。系统发育分析表明，MyD88 的串联重复形成于双壳类分化之前。所有鉴定的 MyD88 均包含死亡结构域（DD）和 Toll/白细胞介素 1 受体（TIR）结构域，并且 13 种软体动物 MyD88 具有低复杂度区域（LCR），而人类和斑马鱼的 MyD88 中没有发现这些区域。基因组结构表明，大多数软体动物 MyD88（19 个中的 14 个）含有 5 个保守内含子，其中 4 个在人类和斑马鱼中发现。此外，PfmmyD88-2（Pinctada fucata martensii 中鉴定的两个 MyD88 之一）的 cDNA 全长获得了 1591bp，包括 260bp 的 5'UTR、257bp 的 3'UTR 和 1077bp 的开放阅读框，编码 358 个氨基酸。定量实时 PCR 分析表明，PfmmyD88-2mRNA 在所有检测组织中广泛表达。最高表达水平在鳃中，其次是肝胰腺和足部。脂多糖刺激后，PfmmyD88-2 表达水平增加，在 12h 时达到最高水平，然后逐渐降至正常水平。PfmmyD88-2 在 HEK293T 中的过表达增加了 pNF-κB-Luc 报告基因的荧光素酶活性。我们还鉴定了 PfmmiR-4047 可以调节 PfmmyD88-2 的表达。这些结果有助于阐明软体动物免疫反应的机制。
