The Molecular Mechanism Involved in the Sensory Axonal Projection toward the Spinal Cord

点击翻译按钮获取中文摘要

During early development, centrally projecting dorsal root ganglion (DRG) neurons extend their axons toward the dorsal spinal cord. We found the involvement of dorsal spinal cord-derived chemoattraction in this projection. However, the molecular nature of this attraction is not clear. We showed that laminin-1 (α1β1γ1) is expressed strongly along the pathway of DRG axons and that its 67-kDa receptor (67LR) was present on DRG cells. By employing culture assays, we showed that laminin-1 or the YIGSR peptide, a soluble peptide of the laminin β1 chain, promoted the DRG axonal response to dorsal spinal cord-derived chemoattraction. By using a function-blocking antibody against 67LR, we showed that the anti-67LR antibody blocked the modulation of DRG axonal response by the YIGSR peptide in vitro. Furthermore, the in ovo injection of the anti-67LR antibody inhibited the DRG axonal growth, toward the dorsal spinal cord. These results provide evidence that the YIGSR peptide promotes dorsal spinal cord-derived chemoattraction via 67LR to contribute to the formation of the initial trajectories of developing DRG axons. Next, to identify novel genes differentially expressed in an early dorsal spinal cord, we used the Kazusa cDNA array system and laser capture microdissection. We observed that a certain population of genes showed significantly increased expression in the dorsal spinal cord.