Chen Q, Fletcher G H, Steinbach J H
Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
J Neurosci Res. 1995 Apr 1;40(5):606-12. doi: 10.1002/jnr.490400505.
We had earlier found that the numbers of mouse muscle nicotinic receptors expressed on the surface of individual cells of a stably transfected clonal line of quail fibroblasts varied from cell to cell (Kopta and Steinbach: J Neurosci 14:3922-3933, 1994). We have now used repeated selective passages of these clonal cells to produce a population of cells which expresses a greater and more uniform number of surface receptors per cell. The increased level is stable over many cell divisions, and over many half-lives for the metabolic degradation of the surface receptors. Selection was performed by adhesion to a surface coated with a monoclonal antibody to a surface epitope on the muscle receptor, followed by expansion of the most tightly attached population of cells. Studies of the selected cells show that the surface receptors contain all four subunits of the muscle nicotinic receptor, and the functional properties of the receptors appear normal. The metabolic stability of the surface receptors is not altered, while the amount of mRNA for the subunits is increased in the selected population of cells. These observations indicate that the more likely reason for increased expression is a transcriptional effect, and that translational or posttranslational changes are unlikely.
我们之前发现，在鹌鹑成纤维细胞的稳定转染克隆系的单个细胞表面表达的小鼠肌肉烟碱样受体数量在细胞之间存在差异（科帕和斯坦巴赫：《神经科学杂志》14:3922 - 3933，1994）。我们现在通过对这些克隆细胞进行反复的选择性传代，产生了一个细胞群体，每个细胞表达的表面受体数量更多且更均匀。增加的水平在许多细胞分裂过程中以及表面受体代谢降解的许多半衰期内都是稳定的。选择过程是通过使细胞黏附到涂有针对肌肉受体表面表位的单克隆抗体的表面，然后扩增黏附最紧密的细胞群体来进行的。对所选细胞的研究表明，表面受体包含肌肉烟碱样受体的所有四个亚基，并且受体的功能特性似乎正常。表面受体的代谢稳定性没有改变，而在所选细胞群体中亚基的mRNA量增加了。这些观察结果表明，表达增加的更可能原因是转录效应，而翻译或翻译后变化不太可能。
