Neuropathogenesis caused by poliovirus and neural cell function

我们发现脊髓灰质炎病毒受体（PVR）的两种膜结合亚型PVRα和PVRδ在极化上皮细胞的细胞膜上有不同的定位。PVRα呈基底外侧分布，PVRδ呈非极化分布。我们证明PVRα的基底外侧分选是由于其胞质尾区的酪氨酸基序。该酪氨酸基序与网格蛋白接头复合物AP-1B的亚基μ1B相互作用。已知μ1B将带有酪氨酸基序的膜结合分子募集到基底外侧表面。这些证据表明μ1B通过与PVRα的酪氨酸基序相互作用将PVRα招募到基底外侧表面。我们发现，抗PV或抗PVR抗体治疗可预防PV感染引起的神经母细胞瘤细胞病变。在此条件下，宿主蛋白质合成一度下降，然后恢复到正常水平。相反，病毒蛋白质合成先增加后减少。已知PV 2A蛋白酶涉及eIF 4G的切割，eIF 4G是Cap依赖性翻译的因子之一。2A的量与细胞中切割的eIF 4G的量相关。这些结果表明，细胞破碎效应的表达可能在翻译阶段受到调节，我们提出了一个假说，即PV是从依赖PVR的神经细胞的突触末端被内吞的，含有PV的囊泡由胞浆动力蛋白逆行转运到细胞体。结果表明，细胞质动力蛋白与PVR的胞质尾区相互作用。构建了表达BDNF的复制型PV载体，并将其注射入PV敏感转基因小鼠的中枢神经系统。BDNF和PV抗原在脊髓运动神经元特异性表达。该载体稳定复制至至少第三代。

We discovered that two membrane bound isoforms of poliovirus receptor (PVR), PVRα and PVRδ, showed different localization on the cell membrane of polarized epithelial cells. PVRα displayed basolateral localization although PVRδ showed non-polarized distribution. We demonstrated that basolateral sorting of PVRα was due to tyrosine motif in its cytoplasmic tail. This tyrosine motif interacted with μ1B, a subunit of clathrin adaptor complex AP-1B. It is known that μ1B recruits membrane bound molecules bearing the tyrosine motif to basolateral surface. These evidences suggest that μ1B recruits PVRα to basolateral surface by interacting the tyrosine motif of PVRα.We found that treatment with anti-PV or anti-PVR antibodies prevented cytopathic effect caused by PV infection in neuroblastoma cells. Under these conditions, host protein synthesis once decreased and then recovered to the normal extent. On the contrary, viral protein synthesis once increased and then decreased. It is known that PV 2A protease relates to cleavage of eIF4G, one of the factors for Cap dependent translation. The amount of 2A correlated with that of cleaved eIF4G in the cells. These results indicate the possibility that expression of cytopthic effect is regulated at the stage of translation.We proposed a hypothesis that PV is endocytosed from the synapse end of neural cells dependent of PVR, and the vesicles containing PV is retrogradely transported by cytoplasmic dynein to the cell body. It was suggested that cytoplasmic dynein interacts with the cytoplasmic tail of PVR. The motif necessary for the interaction was also revealed.Replication competent PV vector that expresses BDNF was constructed and injected into the central nervous system of PV sensitive transgenic mice. BDNF and PV antigens were expressed specifically at motor neuron in the spinal cord. This vector replicated stably up to at least the third passage.