Expression of a Soluble Isoform of Cell Adhesion Molecule 1 in the Brain and Its Involvement in Directional Neurite Outgrowth
Expression of a Soluble Isoform of Cell Adhesion Molecule 1 in the Brain and Its Involvement in Directional Neurite Outgrowth
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DOI：
10.2353/ajpath.2009.080743
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发表时间：
2009-06-01
影响因子：
6
通讯作者：
Ito, Akihiko
中科院分区：
文献类型：
--
作者：
Hagiyama, Man;Ichiyanagi, Naoki;Ito, Akihiko
细胞黏附分子I(CADM1)是一种免疫球蛋白超家族成员，表达于颈上神经节突起上，通过跨亲和性结合介导细胞与细胞间的黏附。除了膜结合形式，我们以前已经证明，通过选择性剪接产生的可溶性形式(SCADM1)在免疫球蛋白样结构域的下游立即具有终止密码子。在这里，我们展示了sCADM1在体内的存在及其在神经突起延伸中的可能作用。SCADM1似乎是一种基质蛋白，因为抗CADM1抗体染色的细胞外限制，而不是细胞内限制，从小鼠脑中提取的基质蛋白丰富。将小鼠浆细胞瘤细胞P3U1修饰成与免疫球蛋白(Ig)G Fc部分(sCADM1-Fc)或其缺失形式(Delta sCADM1-Fc)融合的sCADM1。当表达sCADM1-Fc或Delta sCADM1-Fc的P3U1衍生物被植入胶原凝胶中时，Fc-融合蛋白在细胞周围出现得更丰富。将颈上神经节神经元、亲代P3U1及其衍生物分别植入胶原凝胶中，共培养4d。凝胶切片的Bodian染色显示，大多数颈上神经节突起转向sCADM1-Fc的来源，而不是Delta sCADM1-Fc。此外，sCADM1-Fc和膜结合的CADM1的免疫荧光信号共定位于神经突起表面。这些结果表明，sCADM1似乎通过作为锚定参与了轴突的定向延伸，突起上的膜结合的CADM1可以与之结合。(Am J Pathol 2009174：2278-2289；DOI：10.2353/ajpath.2009.080743)
Cell adhesion molecule I (CADM1), an immunoglobulin superfamily member, is expressed on superior cervical ganglion neurites and mediates cell-cell adhesion by trans-homophilic binding. in addition to the membrane-bound form, we have previously shown that a soluble form (sCADM1) generated by alternative splicing possesses a stop codon immediately downstream of the immunoglobulin-like domain. Here, we demonstrate the presence of sCADM1 in vivo and its possible role in neurite extension. sCADM1 appears to be a stromal protein because extracellular-restricted, but not intracellular-restricted, anti-CADM1 antibody stained stromal protein-rich extract from mouse brains. Murine plasmacytoma cells, P3U1, were modified to secrete sCADM1 fused with either immunoglobulin (Ig)G Fc portion (sCADM1-Fc) or its deletion form that lacks the immunoglobulin-like domain (Delta sCADM1-Fc). When P3U1 derivatives expressing sCADM1-Fc or Delta sCADM1-Fc were implanted into collagen gels, Fc-fused proteins were present more abundantly around the cells. Superior cervical ganglion neurons, parental P3U1, and either derivative were implanted into collagen gels separately, and co-cultured for 4 days. Bodian staining of the gel sections revealed that most superior cervical ganglion neurites turned toward the source of sCADM1-Fc, but not Delta sCADM1-Fc. Furthermore, immunofluorescence signals for sCADM1-Fc and membrane-bound CADM1 were co-localized on the neurite surface. These results show that sCADM1 appears to be involved in directional neurite extension by serving as an anchor to which membrane-bound CADM1 on the neurites can bind. (Am J Pathol 2009, 174:2278-2289; DOI: 10.2353/ajpath.2009.080743)