Isolation and functional analysis of a cDNA for human Jagged2, a gene encoding a ligand for the Notch1 receptor
Isolation and functional analysis of a cDNA for human Jagged2, a gene encoding a ligand for the Notch1 receptor
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DOI：
10.1128/mcb.17.10.6057
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发表时间：
1997-10-01
影响因子：
5.3
通讯作者：
Sklar, J
中科院分区：
文献类型：
--
作者：
Luo, B;Aster, JC;Sklar, J
通过Notch受体的信号传导涉及从线虫到人类的动物中细胞分化的控制。从一个人表达的序列标签开始，该序列包含类似于Serrate的序列，Serrate是果蝇Notch的配体基因，我们从重叠的cDNA克隆中组装了一个全长cDNA，现在称为人Jagged 2，全长cDNA编码与Serrate具有广泛序列同源性的多肽（40.6%的同一性和58.7%的相似性）和甚至更大的同源性，随后已被描述的几个推定的哺乳动物Notch配体。当进行原位杂交时，发现小鼠锯齿状蛋白2同源物的表达在胎儿胸腺、表皮、前肠、背根神经节和内耳中最高。在来自2周龄小鼠组织的RNA的北方印迹分析中，5.0-kb Jagged 2转录物在心脏、肺、胸腺、骨骼肌、脑和睾丸中最丰富。免疫组织化学显示，在胸腺和其他胎鼠组织中，Jagged 2和Notch 1共表达，这与体内两种蛋白质的相互作用一致。表达人锯齿蛋白2的成纤维细胞与鼠C2 C12成肌细胞共培养抑制了肌原性分化，伴随着Notch 1的增加和一种新的115 kDa Notch 1片段的出现。C2 C12细胞暴露于Jagged 2导致Notch mRNA以及第二Notch受体Notch 3和第二Notch配体Jagged 1的mRNA的量增加。C2 C12细胞中Notch 1的组成型活性形式也诱导同一组mRNA的水平增加，表明这些基因的正反馈控制由Jagged 2与Notch 1的结合引发，这种反馈控制可以在体内起作用，以协调采用相同细胞命运的某些祖细胞群之间的分化。
Signaling through Notch receptors has been implicated in the control of cellular differentiation in animals ranging from nematodes to humans. Starting from a human expressed sequence tag-containing sequence resembling that of Serrate, the gene for a ligand of Drosophila melanogaster Notch, we assembled a full-length cDNA, now called human Jagged2, from overlapping cDNA clones, The full-length cDNA encodes a polypeptide having extensive sequence homolog to Serrate (40.6% identity and 58.7% similarity) and even greater homology to several putative mammalian Notch ligands that have subsequently been described. When in situ hybridization was performed, expression of the murine Jagged2 homolog was found to be highest in fetal thymus, epidermis, foregut, dorsal root ganglia, and inner ear. in Northern blot analysis of RNA from tissues of 2-week-old mice, the 5.0-kb Jagged2 transcript was most abundant in heart, lung, thymus, skeletal muscle, brain, and testis. Immunohistochemistry revealed coexpression of Jagged2 and Notch1 within thymus and other fetal murine tissues, consistent with interaction of the two proteins in vivo. Coculture of fibroblasts expressing human Jagged2 with murine C2C12 myoblasts inhibited myogenic differentiation, accompanied by increased Notch1 and the appearance of a novel 115-kDa Notch1 fragment. Exposure of C2C12 cells to Jagged2 led to increased amounts of Notch mRNA as well as mRNAs for a second Notch receptor, Notch3, and a second Notch ligand, Jagged1, Constitutively active forms of Notch1 in C2C12 cells also induced increased levels of the same set of mRNAs, suggesting positive feedback control of these genes initiated by binding of Jagged2 to Notch1, This feedback control may function in vivo to coordinate differentiation across certain groups of progenitor cells adopting identical cell fates.