Molecular cloning and characterization of novel developmentally-regulated genes

本研究采用差减克隆的方法，克隆了双丁酰环腺苷酸（dibutyryl cyclic AMP，DcAMP）诱导的小鼠神经元突起生长过程中，N23 K和N27 K的mRNA和蛋白质表达均瞬时上调的cDNAs，它们编码新发现的大鼠神经肽nociceptin的前体蛋白。与其他神经肽前体一样，N23 K/N27 K蛋白在N末端含有富含疏水性氨基酸的推定信号肽。N23 K/N27 K mRNA仅存在于成年小鼠的脑和脊髓中，并且在出生后早期的脑中以较高水平表达。这些结果表明，N23 K/N27 K蛋白不仅作为神经肽前体，而且作为神经元分化的重要组成部分的功能。

We used a subtraction cloning approach to isolate cDNAs of N23K and N27K, whose mRNA and protein are transiently up-regulated in mouse NS20Y cells undergoing neurite outgrowth induced by treatment of dibutyryl cyclic AMP.N23K and N27K encode precursor proteins for a newly discovered rat neuropeptide nociceptin. As with other neuropeptide precursors, the N23K/N27K proteins contain a putative signal peptide rich in hydrophobic amino acids at the N-terminus. N23K/N27K mRNA are present only in brain and spinal cord in adult mouse, and are expressed at higher levels in early postnatal brain. These findings suggest that the N23K/N27K protein function not only as neuropeptide precursors but also as important components in neuronal differentiation.