Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Rd., Qingdao 266071, China.
Fish Shellfish Immunol. 2013 May;34(5):1228-35. doi: 10.1016/j.fsi.2013.02.002. Epub 2013 Feb 24.
Opioid growth factor receptor (OGFR) is a receptor for [Met(5)]-enkephalin and plays important roles in the regulation of cell growth and embryonic development. In the present study, a cDNA of 2381 bp for the scallop Chlamys farreri OGFR (designated as CfOGFR) was identified by rapid amplification of cDNA ends (RACE) approach and expression sequence tag (EST) analysis. The complete cDNA sequence of CfOGFR contained an open reading frame (ORF) of 1200 bp, which encoded a protein of 399 amino acids. The amino acid sequence of CfOGFR shared 33-64% similarity with other OGFRs. There was a low complexity domain and a conserved OGFR_N domain at the N-terminal of CfOGFR. The mRNA transcripts of CfOGFR were constitutively expressed in the tested tissues with the highest expression level in hepatopancreas. During the early embryonic development, the mRNA transcripts of CfOGFR could be detected in different development stages, where the expression level presented a downward trend as a whole. The stimulations of LPS, Glu and poly (I:C) significantly induced the expression of CfOGFR mRNA in hemocytes (P < 0.05), while PGN stimulation exerted no influence. Co-IP and western blot results revealed that the CfOGFR in hemocytes displayed high affinity and specificity to [Met(5)]-enkephalin. Exogenous [Met(5)]-enkephalin was observed to inhibit the proliferation of HEK293T cells transfected with pcDNA3.1(+)-CfOGFR in a time and dosage dependent manner. These results collectively indicated that CfOGFR, as a homolog of OGFRs in C. farreri, played an important role in cells proliferation, and might be involved in the immune response of scallops.
阿片样生长因子受体（OGFR）是 [Met(5)]-脑啡肽的受体，在细胞生长和胚胎发育的调节中发挥重要作用。本研究采用快速扩增 cDNA 末端（RACE）和表达序列标签（EST）分析方法，从栉孔扇贝（Chlamys farreri）中鉴定出一个 2381bp 的 cDNA，命名为 CfOGFR。CfOGFR 的完整 cDNA 序列包含一个 1200bp 的开放阅读框（ORF），编码 399 个氨基酸的蛋白质。CfOGFR 的氨基酸序列与其他 OGFR 具有 33-64%的相似性。CfOGFR 的 N 端有一个低复杂度结构域和一个保守的 OGFR_N 结构域。CfOGFR 的 mRNA 转录本在测试的组织中持续表达，在肝胰腺中表达水平最高。在早期胚胎发育过程中，CfOGFR 的 mRNA 转录本可在不同的发育阶段检测到，整体表达水平呈下降趋势。LPS、Glu 和 poly（I:C）刺激显著诱导血细胞中 CfOGFR mRNA 的表达（P<0.05），而 PGN 刺激没有影响。Co-IP 和 Western blot 结果表明，血细胞中的 CfOGFR 与 [Met(5)]-脑啡肽具有高亲和力和特异性。外源性 [Met(5)]-脑啡肽被观察到以时间和剂量依赖的方式抑制 pcDNA3.1(+)-CfOGFR 转染的 HEK293T 细胞的增殖。这些结果共同表明，CfOGFR 作为栉孔扇贝 OGFRs 的同源物，在细胞增殖中发挥重要作用，可能参与扇贝的免疫反应。
