Sekiguchi K, Yokota C, Asashima M, Kaname T, Fan Q W, Muramatsu T, Kadomatsu K
Department of Biochemistry, Nagoya University School of Medicine.
J Biochem. 1995 Jul;118(1):94-100. doi: 10.1093/oxfordjournals.jbchem.a124898.
Midkine (MK) is a heparin-binding growth factor and forms a novel protein family together with another member, pleiotrophin (PTN)/heparin-binding growth-associated molecule (HB-GAM). A cDNA clone isolated from Xenopus laevis specifies for the Xenopus counterpart of MK (XMK), and the mode of XMK expression was studied by in situ hybridization and Northern blot analysis. XMK was first expressed at stage 11 (middle gastrula) and was located in the neural anlage at stage 12 (late gastrula). Through stage 13 to 15 (early neurula), XMK expression was restricted to the neural folds. At stage 23 (tailbud stage), XMK was predominantly localized in the brain and neural tube. At the larva stage, XMK expression was again restrictedly observed in the brain, the optic vesicles, the otic vesicle, and the spinal cord, all of which are derivatives of the neural tube, as well as in the branchial arches, derivatives of the cranial neural crest. Comparing the mode of MK expression between Xenopus and the mouse, we propose that MK plays evolutionally conserved roles in neurogenesis and development of the craniofacial architecture of ectomesenchymal origin. We also found that XMK was expressed in various adult organs; strong expression was observed in the brain, the eye and the spinal cord, all of which showed intense MK expression at the larva stage.
中期因子（MK）是一种肝素结合生长因子，与另一个成员多效蛋白（PTN）/肝素结合生长相关分子（HB-GAM）共同构成一个新的蛋白质家族。从非洲爪蟾分离得到的一个cDNA克隆编码非洲爪蟾的中期因子对应物（XMK），并通过原位杂交和Northern印迹分析研究了XMK的表达模式。XMK在第11期（中胚层期）开始首次表达，在第12期（晚胚层期）位于神经原基。从第13期到15期（早期神经胚期），XMK的表达局限于神经褶。在第23期（尾芽期），XMK主要定位于脑和神经管。在幼虫期，XMK的表达再次局限于脑、视泡、听泡和脊髓，所有这些都是神经管的衍生物，以及鳃弓，即颅神经嵴的衍生物。比较非洲爪蟾和小鼠中MK的表达模式，我们认为MK在神经发生和外胚间充质来源的颅面结构发育中发挥着进化上保守的作用。我们还发现XMK在各种成体器官中表达；在脑、眼和脊髓中观察到强表达，所有这些在幼虫期都显示出强烈的MK表达。
