The four-and-a-half LIM-only protein family of transcription co-factors participates in various cellular processes, such as cell proliferation, cell differentiation, apoptosis, cell adhesion, migration, transcription and signal transduction. However, the knowledge of the structural characteristics and immune functions of its ancestor Lmpt, which contains six LIM domains at the C-terminus and a PET domain at the N-terminus, is limited in invertebrates, especially in crustaceans. In the present study, a novel Lmpt from oriental river prawn (Macrobrachium nipponense) was identified, and its role in the immune response was investigated. Its full-length cDNA sequence was 6407 bp, which contained a 2595 bp ORF encoding 865 amino acids, exhibiting high similarity to the structure of Lmpt derived from other invertebrates. Tissue distribution analysis revealed that MnLmpt was widely expressed in all examined tissues, and high expression levels were observed in muscle, heart and intestine in M. nipponense. After experimental challenges with bacteria and virus, the transcription levels of MnLmpt significantly fluctuated in gill and hepatopancreas, indicating that it might play a role in the innate immune response in M. nipponense. Silencing of MnLmpt by dsRNA injection in vivo could promote bacterial growth, suggesting that MnLmpt exerted an antibacterial immune function in prawn. Immunocytochemistry assay results demonstrated that MnLmpt was able to translocate from the cytoplasm to the nucleus after being stimulated with pathogens. The expression levels of NF-κB signalling cascade members, such as dorsal, relish, TAK1, TAB1, Ikkβ, and Ikkε, and AMPs, including ALF4, Cru1, and Cru2, exhibited significant downregulation in the MnLmpt silenced group. Similarly, dual-luciferase reporter assays also demonstrated that MnLmpt could stimulate an NF-κB signalling cascade. Meanwhile, all of the LIM domains of MnLmpt could trigger NF-κB signalling; however, their cumulative effect on NF-κB promoter activation was hardly observed. These results showed that MnLmpt might play a crucial role in the innate immune response in M. nipponense, and these findings paved the way for a better understanding of the immune system in crustacean species.

四个半 LIM-only 蛋白家族的转录辅因子参与各种细胞过程，如细胞增殖、细胞分化、凋亡、细胞粘附、迁移、转录和信号转导。然而，其祖先 Lmpt 的结构特征和免疫功能的知识在无脊椎动物中是有限的，在无脊椎动物中，尤其是在甲壳类动物中，Lmpt 在 C 端包含六个 LIM 结构域，在 N 端包含一个 PET 结构域。在本研究中，一种来自东方河虾 (Macbrachium nipponense ) 的新型 Lmpt) 被鉴定，并研究了其在免疫反应中的作用。其cDNA全长6407 bp，包含一个2595 bp的ORF，编码865个氨基酸，与其他无脊椎动物Lmpt的结构具有高度相似性。组织分布分析表明，MnLmpt在所有检查的组织中广泛表达，并且在M. nipponense的肌肉、心脏和肠中观察到高表达水平。在细菌和病毒的实验挑战后，MnLmpt在鳃和肝胰腺中的转录水平显着波动，表明它可能在M. nipponense的先天免疫反应中发挥作用。通过 dsRNA 注射沉默MnLmptin vivo可以促进细菌生长，表明Mn Lmpt在对虾中发挥抗菌免疫功能。免疫细胞化学分析结果表明，Mn Lmpt 在受到病原体刺激后能够从细胞质转移到细胞核。NF-κB 信号级联成员（例如背侧、津津乐道、TAK1、TAB1、Ikkβ 和 Ikkε）和 AMP（包括 ALF4、Cru1 和 Cru2）的表达水平在MnLmpt沉默组中表现出显着下调。同样，双荧光素酶报告基因分析也证明Mn Lmpt 可以刺激 NF-κB 信号级联。同时，Mn的所有 LIM 域Lmpt 可以触发 NF-κB 信号；然而，几乎没有观察到它们对 NF-κB 启动子激活的累积影响。这些结果表明，Mn Lmpt 可能在M. nipponense的先天免疫反应中发挥关键作用，这些发现为更好地了解甲壳类动物的免疫系统铺平了道路。