Yamada Mayumi, Hashimoto Takashi, Hayashi Noriko, Higuchi Maiko, Murakami Akira, Nakashima Toshihiro, Maekawa Shohei, Miyata Seiji
Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
Brain Res. 2007 Aug 24;1165:5-14. doi: 10.1016/j.brainres.2007.04.062. Epub 2007 Apr 27.
Opioid-binding cell adhesion molecule (OBCAM) is the member of the IgLON family, a subgroup of the immunoglobulin superfamily. In the present study, the functions and dynamics of OBCAM were investigated in hippocampal neurons in vitro. Western blotting revealed that OBCAM expression was low at early stages of culture but it was increased as culture development. Double labeling immunofluorescence microscopy showed that OBCAM immunoreactivity was localized mainly at postsynaptic spines labeled with phalloidin and anti-PSD-95. The inhibition of OBCAM function with the specific antibody resulted in a significant decrease in the number of synapses on dendrites compared with control mouse IgG. The suppression of OBCAM expression using the antisense oligodeoxynucleotide also impaired the formation of synapses compared with control universal ones. The overexpression of OBCAM mRNA using a plasmid vector augmented the formation of synapses. Moreover, the internalization of OBCAM was promoted with increased neuronal activity by 4-aminopyridine. This internalization was reduced with the treatment of filipin, a sterol agent, indicating that this process is a raft-dependent pathway. These results indicate that OBCAM is a synaptic cell adhesion molecule concerning synaptogenesis and its surface localization is dynamically regulated in response to neuronal activity.
阿片样物质结合细胞粘附分子（OBCAM）是免疫球蛋白超家族亚组IgLON家族的成员。在本研究中，对体外培养的海马神经元中OBCAM的功能和动态变化进行了研究。蛋白质印迹分析显示，在培养早期OBCAM表达较低，但随着培养时间的延长而增加。双重免疫荧光显微镜检查表明，OBCAM免疫反应性主要定位于用鬼笔环肽和抗PSD-95标记的突触后棘。与对照小鼠IgG相比，用特异性抗体抑制OBCAM功能导致树突上突触数量显著减少。与对照通用寡脱氧核苷酸相比，使用反义寡脱氧核苷酸抑制OBCAM表达也损害了突触的形成。使用质粒载体过表达OBCAM mRNA增强了突触的形成。此外，4-氨基吡啶增加神经元活性可促进OBCAM的内化。用甾醇试剂制霉菌素处理可减少这种内化，表明该过程是一种依赖脂筏的途径。这些结果表明，OBCAM是一种与突触发生有关的突触细胞粘附分子，其表面定位可根据神经元活动进行动态调节。
