湘云鲫2号肠道干细胞标志物LGR6分子特征及其多克隆抗体制备

Molecular characterization and polyclonal antibody preparation of intestinal stem cell marker LGR6 in Xiangyun crucian carp 2

  • 摘要: 【目的】克隆湘云鲫2号肠道干细胞标志物LGR6(3nLGR6)并制备多克隆抗体,为从肠道干细胞角度揭示湘云鲫2号的抗病机制提供技术支持。【方法】通过PCR扩增3nLGR6基因开放阅读框(ORF)序列,采用InterProScan、TMHMM Server 2.0、ExPASy Proteomics Server、SignalP 5.0、PSORTⅡPrediction、SoftBerry-Psite、SWISS-MODEL及MEGA 11.0等在线软件进行生物信息学分析;利用原核表达系统表达融合蛋白,以纯化的融合蛋白免疫BALB/c雌性小鼠制备多克隆抗体,基于免疫组织化学分析3nLGR6在湘云鲫2号肠组织中的分布情况。【结果】3nLGR6基因ORF序列全长2874 bp,共编码957个氨基酸残基;3nLGR6蛋白理论分子量约105.4 kD,理论等电点(p I)为5.44,在其N端有1个亮氨酸重复序列结构域,C端存在1个7次跨膜结构的GPCR结构域,且在18Gly与19Ser间存在信号肽切割位点(Sec信号肽)。3nLGR6与其他硬骨鱼类的LGR6氨基酸序列高度同源,其中与二倍体斑马鱼的相似性为92.28%。与鱼类LGR6作用密切的基因有LGR4、RNF43、RSPO2、CTNNB1、APCCTNNA1,主要涉及Wnt信号通路和Adherens junction信号通路。以纯化得到的融合蛋白3nLGR6免疫BALB/c雌性小鼠,能成功制备出小鼠抗3nLGR6多克隆抗体,且免疫组化试验结果显示该抗体可特异性识别湘云鲫2号肠道组织中的3nLGR6。【结论】3nLGR6与其他物种的LGR6氨基酸序列高度同源,其结构和功能相对较保守。制备获得的小鼠抗3nLGR6多克隆抗体能特异性识别湘云鲫2号肠道内源性3nLGR6,为后续深入研究LGR6在硬骨鱼组织中的表达情况及揭示LGR6在肠道黏膜稳态中的作用机制提供了技术支撑。

     

    Abstract: 【Objective】In this study, the intestinal stem cell marker LGR6 of Xiangyun crucian carp 2 was cloned, and the polyclonal antibody was also prepared, which providede technical support for revealing the anti-disease mechanism of Xiangyun crucian carp 2 from the perspective of intestinal stem cells. 【Method】PCR was used to amplify the open reading frame(ORF) sequence of 3nLGR6 gene, and bioinformatics analysis was conducted by InterProScan, TMHMM Server 2.0, ExPASy Proteomics Server, SignalP 5.0, PSORT Ⅱ Prediction, SoftBerry-Psite, SWISS-MODEL and MEGA 11.0. Using the prokaryotic expression system to express furion protein, BALB/c female mice were vaccinated with purified fusion protein to prepare polyclonal antibodies, and the distribution of 3nLGR6 in intestine of Xiangyun crucian carp 2 was analyzed based on immunohistochemical analysis. 【Result】The ORF sequence of 3nLGR6 gene was 2874 bp in length and encoded 957 amino acids residues. The theoretical molecular weight of 3nLGR6 protein was approximately 105.4 kD, with a theoretical isoelectric point(pI) of 5.44. It had a leucine repeat domain at its N-terminus, a seven transmembrane GPCR domain at its C-terminus, and a signal peptide cleavage site between 18Gly and 19Ser(Sec signal peptide). 3nLGR6 had high homology with LGR6 sequences of other amino acid teleost, with the identity of 92.28% with the triploid zebrafish. The closely related genes to LGR6 in fish, including LGR4, RNF43, RSPO2, CTNNB1, APC, and CTNNA1, were mainly involved in the Wnt and Adherens junction signaling pathways. The polyclonal antibody against 3nLGR6 was successfully prepared by immunizing BALB/c female mice with purified 3nLGR6 protein, and immunohistochemistry showed that the antibody could specifically recognize 3nLGR6 in the intestine of Xiangyun crucian carp 2.【Conclusion】3nLGR6 is highly homologous to the LGR6 amino acid sequence of other species. The structure and function of 3nLGR6 are relatively conserved. The prepared mouse anti-3nLGR6 antibody can specifically recognize the endogenous 3nLGR6 in the intestine of Xiangyun crucian carp 2. This result provides technical support for further studies on the expression of LGR6 in teleost tissues and the mechanisms underlying the role of LGR6 regulating intestinal mucosal homeostasis.

     

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