A role of CD9 in pain pathway of spinal dorsal horn

四跨膜蛋白CD9作为分子清道夫，收集信号分子并帮助组织细胞中有效信号转导的特定位点。本研究的目的是阐明CD9在小鼠脊髓背角和三叉神经脊束核的细胞定位及其与其他疼痛相关分子的关系。结果表明：1）CD9常与其他四跨膜蛋白形成功能复合物，尤其是与CD81和CD151形成功能复合物，但这两种蛋白在脊髓背角没有特异性分布。2)在人类脊髓中观察到了类似的CD 9分布模式（与新泻大学Takahashi博士合作，脑研究所），这表明该蛋白可能也参与了人类的疼痛信号传导。3)使用脊髓切片，其中绿色荧光蛋白 ...更多信息 在胶质细胞酸性蛋白（GFAP）启动子的调控下，在星形胶质细胞中特异性表达CD9，并进行背神经节细胞培养，检测CD9的细胞分布。与TRPV1和其他疼痛相关分子类似，CD9存在于背角I和II层DRG神经元的轴突终末。4)已知CD9以细胞外信号依赖性方式与Gq蛋白和PKC结合。有趣的是，Gq和PKC的一个亚型也集中在背角，然而，CD9与这些分子特异性结合的直接证据目前还没有得到免疫沉淀方法。这些信号分子与CD9在疼痛通路中的关系尚在研究中。此外，我们发现CD9在发育早期就在DRG神经元中表达，并且在部分（但不是全部）CD9基因敲除小鼠中，DRG的形态和细胞排列出现异常，提示该分子可能也参与了发育过程中感觉通路的形成。目前正在编写与这项研究有关的手稿。少

Tetraspanin CD9 acts as molecular scavenger, which collects signaling molecules and help to organize the specific site for effective signal transduction in the cells. Previously, we found that CD9 was concentrated in the superficial layers (I and II) of the dorsal horn of mouse spinal cord and the spinal trigeminal nucleus, both of which are main pain pathways, The purpose of this study was to clarify the cellular localization of CD9 and the relationship with other pain-related molecules. This following results were obtained.1) CD9 often forms functional complex with other tetraspanins, especially with CD81 and CD151, however, both proteins did not show any specific distributions in the dorsal horn. 2) The similar distribution pattern of CD9 was observed in human spinal cord (collaboration with Dr. Takahashi, Niigata Univ., Brain Res. Inst.), suggesting that this protein may be involved in pain signaling in human as well. 3) Using spinal cord sections, in which green fluorescence prote … More in was specifically expressed in astrocytes under the control of glial fibrillary acidic protein (GFAP) promoter, and dorsal ganglion cell culture, cellular distribution of CD9 was examined. Similar to TRPV1 and other pain-related molecules, CD9 was present in axon terminals of DRG neurons of dorsal horn layers I and II. 4) CD9 is known to bind to Gq protein and PKC in an extracellular signal-dependent manner. Interestingly, Gq and a subtype of PKC were also concentrated in dorsal horn, however, direct evidences of specific binding of CD9 with these molecules have not obtained by immunoprecipitaion method at present. The relationship between these signaling molecules and CD9 in pain pathway is still underway. In addition, we found that CD9 was expressed in DRG neuron from relatively early stage of development and the shapes and cell arrangements of DRG were abnormal in some (but not all) of CD9 knockout mice, suggesting that this molecule may be involved in the formation of sensory pathway during development as well. The manuscripts related to this study are now in preparation. Less