Wallace V A, Raff M C
Medical Research Council Developmental Neurobiology Programme, MRC Laboratory for Molecular Cell Biology and the Biology Department, University College London, London WC1E 6BT, UK.
Development. 1999 Jul;126(13):2901-9. doi: 10.1242/dev.126.13.2901.
Retinal ganglion cell (RGC) axons have been shown to stimulate the proliferation of astrocytes in the developing rodent optic nerve, but the signals that mediate this effect have not been identified. The following findings suggest that Sonic hedgehog (Shh) is one of the signals. (1) RGCs express both Shh mRNA and protein, whereas the optic nerve contains the protein but not the mRNA. (2) Astrocytes and their precursors in the developing optic nerve express the Hedgehog (Hh) receptor gene Patched (Ptc), suggesting that they are being signalled by an Hh protein. (3) Ptc expression in the nerve is greatly decreased by either nerve transection or by treatment with neutralizing anti-Shh antibodies, suggesting that it depends on axon-derived Shh. (4) Astrocyte proliferation in the developing nerve is reduced by treatment with anti-Shh antibodies, suggesting that Shh normally helps stimulate this proliferation.
视网膜神经节细胞（RGC）轴突已被证明可刺激发育中的啮齿动物视神经中星形胶质细胞的增殖，但介导这种效应的信号尚未确定。以下发现表明，音猬因子（Shh）是其中一种信号。（1）RGCs表达Shh mRNA和蛋白，而视神经含有该蛋白但不含mRNA。（2）发育中的视神经中的星形胶质细胞及其前体细胞表达Hedgehog（Hh）受体基因Patched（Ptc），表明它们正被一种Hh蛋白信号传导。（3）神经切断或用中和性抗Shh抗体处理后，神经中的Ptc表达大幅降低，表明其依赖于轴突衍生的Shh。（4）用抗Shh抗体处理可减少发育中神经里星形胶质细胞的增殖，表明Shh通常有助于刺激这种增殖。
