Suzuki Masaki, Takamura Yumi, Maéno Mitsugu, Tochinai Shin, Iyaguchi Daisuke, Tanaka Isao, Nishihira Jun, Ishibashi Teruo
Department of Molecular Biochemistry, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Sapporo 060-8638, Japan.
J Biol Chem. 2004 May 14;279(20):21406-14. doi: 10.1074/jbc.M311416200. Epub 2004 Mar 15.
Macrophage migration inhibitory factor (MIF) is an immunoregulatory cytokine involved in both acquired and innate immunity. MIF also has many functions outside the immune system, such as isomerase and oxidoreductase activities and control of cell proliferation. Considering the involvement of MIF in various intra- and extracellular events, we expected that MIF might also be important in vertebrate development. To elucidate the possible role of MIF in developmental processes, we knocked down MIF in embryos of the African clawed frog Xenopus laevis, using MIF-specific morpholino oligomers (MOs). For the synthesis of the MOs, we cloned a cDNA for a Xenopus homolog of MIF. Sequence analysis, determination of the isomerase activity, and x-ray crystallographic analysis revealed that the protein encoded by the cDNA was the ortholog of mammalian MIF. We carried out whole mount in situ hybridization of MIF mRNA and found that MIF was expressed at high levels in the neural tissues of normal embryos. Although early embryogenesis of MO-injected embryos proceeded normally until the gastrula stage, their neurulation was completely inhibited. At the tailbud stage, the MO-injected embryos lacked neural and mesodermal tissues, and also showed severe defects in their head and tail structures. Thus, MIF was found to be essential for axis formation and neural development of Xenopus embryos.
巨噬细胞移动抑制因子（MIF）是一种参与获得性免疫和固有免疫的免疫调节细胞因子。MIF在免疫系统之外也具有许多功能，例如异构酶和氧化还原酶活性以及对细胞增殖的控制。考虑到MIF参与各种细胞内和细胞外事件，我们预期MIF在脊椎动物发育中可能也很重要。为了阐明MIF在发育过程中的可能作用，我们使用MIF特异性吗啉代寡聚物（MOs）在非洲爪蟾非洲爪蟾的胚胎中敲低MIF。为了合成MOs，我们克隆了非洲爪蟾MIF同源物的cDNA。序列分析、异构酶活性测定和X射线晶体学分析表明，该cDNA编码的蛋白质是哺乳动物MIF的直系同源物。我们对MIF mRNA进行了全胚胎原位杂交，发现MIF在正常胚胎的神经组织中高水平表达。虽然注射MO的胚胎的早期胚胎发育在原肠胚阶段之前正常进行，但其神经胚形成被完全抑制。在尾芽阶段，注射MO的胚胎缺乏神经和中胚层组织，并且在其头部和尾部结构中也表现出严重缺陷。因此，发现MIF对非洲爪蟾胚胎的轴形成和神经发育至关重要。
