Strittmatter S M, Fishman M C, Zhu X P
Developmental Biology Laboratory, Massachusetts General Hospital, Charleston.
J Neurosci. 1994 Apr;14(4):2327-38. doi: 10.1523/JNEUROSCI.14-04-02327.1994.
The high concentration of the GTP-binding protein G(o) in the neuronal growth cone suggests that G(o) activation state may after neurite outgrowth. We find that activation of pertussis toxin-sensitive G-proteins by mastoparan increases neurite outgrowth from neuroblastoma cells. To examine G(o) activation specifically, point mutations homologous to activating, oncogenic mutations in alpha i2 and alpha s were introduced into the alpha subunit of G(o). The stability of the alpha o mutants to tryptic digestion confirms that they are activated. When expressed in PC12 or N1E-115 cells, activated alpha o doubles total neurites length per cell, primarily by increasing the number of neurites per cell. The growth cones of cells expressing activated alpha o are narrower than control growth cones. Expression of wildtype alpha o or the activated alpha subunits of other G-proteins did not affect total neurite length per cell. Thus, factors that lead to activation of G(o) can modulate neurite number per cell.
神经元生长锥中GTP结合蛋白G(o)的高浓度表明，G(o)的激活状态可能影响神经突的生长。我们发现，mastoparan激活百日咳毒素敏感的G蛋白可增加神经母细胞瘤细胞的神经突生长。为了特异性检测G(o)的激活，将与α i2和α s中激活的致癌突变同源的点突变引入G(o)的α亚基。α o突变体对胰蛋白酶消化的稳定性证实它们被激活。当在PC12或N1E-115细胞中表达时，激活的α o使每个细胞的总神经突长度增加一倍，主要是通过增加每个细胞的神经突数量。表达激活的α o的细胞的生长锥比对照生长锥更窄。野生型α o或其他G蛋白的激活α亚基的表达不影响每个细胞的总神经突长度。因此，导致G(o)激活的因素可以调节每个细胞的神经突数量。
