College of Animal Sciences, Zhejiang University, Hangzhou, 310058, China.
College of Animal Sciences, Zhejiang University, Hangzhou, 310058, China.
Fish Shellfish Immunol. 2020 Oct;105:41-52. doi: 10.1016/j.fsi.2020.07.002. Epub 2020 Jul 3.
Transforming growth factor-β type III receptor (TβR3), as a co-receptor of TGF-β superfamily, plays critical roles in development and growth as well as some disease pathogeneses by presenting ligands to other receptors in vertebrates. However, the identification and functional characterization of TβR3 had not been reported yet in invertebrates. In the present study, TβR3 was first identified and characterized in mud crab Scylla paramamosain. The obtained cDNA length of SpTβR3 was 2, 424 bp with a 1, 854 bp open reading frame, which encoded a putative peptide of 617 amino acids containing a typical transmembrane region and a Zona pellucida (ZP) domain. Real-time PCR results showed that SpTβR3 was predominantly expressed at early embryonic development stage and early postmolt stage, suggesting its participation in development and growth. We report, for the first time in invertebrates, the challenge of both Vibro alginolyticus and Poly (I:C) could alter the expression patterns of SpTβR3. Notably, the expression levels of SpIKK, two NF-κB members (SpRelish and SpDorsal), and five antimicrobial peptide genes (SpCrustin and SpALF1-4) were significantly suppressed when SpTβR3 was interfered in vivo. Secondly, the overexpression of SpTβR3 in vitro could activate NF-κB signaling through the dual-luciferase reporter assays. Furthermore, the bacterial clearance assay after SpTβR3 was silenced in vivo highlighted the potential of SpTβR3 in activating the innate immune responses. These results implied the involvement of SpTβR3 in the innate immune responses by regulating the NF-κB pathway. This study first indicated that TβR3 was present in invertebrate, and it participated in not only the development and growth but also the innate immunity of S. paramamosain. It also provided new insights into the origin or evolution of TGF-β receptors in crustacean species and even in invertebrates.
转化生长因子-β 型 III 受体（TβR3）作为 TGF-β 超家族的共受体，在脊椎动物中通过将配体呈现给其他受体，在发育和生长以及一些疾病发病机制中发挥关键作用。然而，在无脊椎动物中尚未报道 TβR3 的鉴定和功能特征。在本研究中，首次在泥蟹 Scylla paramamosain 中鉴定和表征了 TβR3。获得的 SpTβR3 cDNA 长度为 2,424bp，具有 1,854bp 的开放阅读框，编码一个假定的 617 个氨基酸肽，其中包含一个典型的跨膜区域和一个 Zona pellucida（ZP）结构域。实时 PCR 结果显示，SpTβR3 在早期胚胎发育阶段和早期蜕皮后阶段表达水平较高，表明其参与了发育和生长。我们首次报道，在无脊椎动物中，Vibro alginolyticus 和 Poly（I:C）的挑战都可以改变 SpTβR3 的表达模式。值得注意的是，当体内干扰 SpTβR3 时，SpIKK、两个 NF-κB 成员（SpRelish 和 SpDorsal）和五个抗菌肽基因（SpCrustin 和 SpALF1-4）的表达水平显著受到抑制。其次，体外过表达 SpTβR3 通过双荧光素酶报告基因检测可激活 NF-κB 信号通路。此外，体内沉默 SpTβR3 后进行的细菌清除试验突出了 SpTβR3 激活先天免疫反应的潜力。这些结果表明，SpTβR3 通过调节 NF-κB 通路参与先天免疫反应。本研究首次表明，TβR3 存在于无脊椎动物中，它不仅参与了发育和生长，还参与了 S. paramamosain 的先天免疫。它还为甲壳动物物种甚至无脊椎动物中 TGF-β 受体的起源或进化提供了新的见解。
