Motile sperm domain containing 2 (MOSPD2) is a single-pass membrane protein to which until recently little function had been ascribed. Although its mammalian homologs have been identified, the status of the mospd2 gene in lower vertebrates is still unknown. In the present study, cDNA of the mospd2 gene of barbel steed (Hemibarbus labeo) was cloned and sequenced to characterize its potential involvement in the innate immune system of this fish. Sequence analysis revealed that the predicted barbel steed MOSPD2 protein contained an N-terminal extracellular portion composed of a CRAL-TRIO domain, a motile sperm domain, and a transmembrane domain, as well as a short C-terminal intracellular domain. Phylogenetic tree analysis indicated that barbel steed MOSPD2 is closely related to that of zebrafish. Barbel steed mospd2 transcripts were detected in a wide range of tissues, with the highest level being found in the gill. In response to lipopolysaccharide (LPS) treatment or Aeromonas hydrophila infection, mospd2 gene expression was significantly altered in the head kidney, spleen, and mid-intestine. The expression of mospd2 gene was detected in monocytes/macrophages (MO/MФ), neutrophils, and lymphocytes, and was found to be mainly expressed in MO/MФ. At the same time, using flow cytometry, we also confirmed that MOSPD2 protein is located on MO/MФ, neutrophil, and lymphocyte membranes. Following treatment with LPS or A. hydrophila, MOSPD2 protein expression was induced in these immune cells. The migration of MO/MФ and neutrophils decreased significantly upon MOSPD2 blockade with anti-MOSPD2 IgG in a dose-dependent manner, whereas this treatment had no significant effect on lymphocytes migration. To the best of our knowledge, our study, for the first time, provides evidence that MOSPD2 mediates the migration of MO/MФ and neutrophils in a fish species.

中文翻译：

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杠铃马（Hemibarbus labeo）中MOSPD2同源物的分子特征及其在单核细胞/巨噬细胞和中性粒细胞迁移中的参与。

包含2的运动精子域（MOSPD2）是单次通过的膜蛋白，直到最近才赋予它很少的功能。尽管已经确定了其哺乳动物同源物，但在较低脊椎动物中的mospd2基因的状态仍然未知。在本研究中，克隆并测序了barbel steed（Hemibarbus labeo）的mospd2基因的cDNA，以表征其潜在参与该鱼的先天免疫系统的特征。序列分析显示，预测的barbel sted MOSPD2蛋白包含一个N末端的细胞外部分，该部分由CRAL-TRIO域，运动性精子域和跨膜域以及一个短的C末端胞内域组成。系统进化树分析表明，杠铃马MOSPD2与斑马鱼密切相关。在广泛的组织中检测到Barbel steed mospd2转录本，with中的含量最高。响应脂多糖（LPS）治疗或嗜水气单胞菌感染，mospd2基因表达在头部肾脏，脾脏和肠中部显着改变。在单核细胞/巨噬细胞（MO /MФ），嗜中性粒细胞和淋巴细胞中检测到了mospd2基因的表达，发现其主要在MO /MФ中表达。同时，我们使用流式细胞仪还证实了MOSPD2蛋白位于MO /MФ，中性粒细胞和淋巴细胞膜上。用LPS或亲水曲霉处理后，在这些免疫细胞中诱导了MOSPD2蛋白表达。用抗MOSPD2 IgG阻断MOSPD2后，MO /MФ和中性粒细胞的迁移以剂量依赖性方式显着降低，而这种治疗对淋巴细胞迁移没有明显影响。据我们所知，我们的研究首次提供了证据，证明MOSPD2介导了MO /MФ和中性粒细胞在鱼类中的迁移。