Kibbey M C, Johnson B, Petryshyn R, Jucker M, Kleinman H K
Laboratory of Developmental Biology, National Institute for Dental Research, NIH, Bethesda, Maryland 20892-4370, USA.
J Neurosci Res. 1995 Oct 15;42(3):314-22. doi: 10.1002/jnr.490420305.
The basement membrane protein laminin and the IKVAV-containing sequence from the laminin alpha 1 chain have been found to promote the differentiation of primary neurons and a variety of neural cell lines. We previously reported that a 110-kd IKVAV-binding protein (LBP110) isolated from brain appears to be a member of the beta-amyloid precursor protein (APP) family by immunologic and functional studies, which showed that LBP110/APP is also important in neurite outgrowth (Kibbey et al.: Proc Natl Acad Sci USA 90:10150-10153, 1993). In the preparation of this binding protein, a contaminating IKVAV-binding protein of identical molecular weight, nucleolin, was also identified. Here we have studied the relationship between these binding proteins. We find that nucleolin binds specifically to the IKVAV sequence independently of LBP110/ApP. We have also demonstrated significant levels of nucleolin in mature brain and in differentiating neural cells, suggesting that nucleolin functions not only in cell proliferation and in ribosome biogenesis as was previously reported, but also in the differentiation and maintenance of neural tissue. Our identification of cytoplasmic and cell-surface nucleolin, an IKVAV-binding protein, suggests that this protein may function in signalling by extra-cellular matrix.
已经发现基底膜蛋白层粘连蛋白以及层粘连蛋白α1链中含IKVAV的序列可促进原代神经元和多种神经细胞系的分化。我们先前报道，通过免疫和功能研究，从脑中分离出的一种110-kd IKVAV结合蛋白（LBP110）似乎是β-淀粉样前体蛋白（APP）家族的成员，这表明LBP110/APP在神经突生长中也很重要（Kibbey等人：美国国家科学院院刊90:10150-10153，1993）。在制备这种结合蛋白时，还鉴定出一种分子量相同的污染性IKVAV结合蛋白，即核仁素。在这里，我们研究了这些结合蛋白之间的关系。我们发现核仁素独立于LBP110/ApP特异性结合IKVAV序列。我们还证明在成熟脑和分化的神经细胞中存在大量核仁素，这表明核仁素不仅如先前报道的那样在细胞增殖和核糖体生物发生中起作用，而且在神经组织的分化和维持中也起作用。我们对细胞质和细胞表面核仁素（一种IKVAV结合蛋白）的鉴定表明，这种蛋白可能在细胞外基质信号传导中发挥作用。
