Suzuki T, Usuda N, Murata S, Nakazawa A, Ohtsuka K, Takagi H
Department of Neuroplasticity, Research Center on Aging and Adaptation, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390,
Brain Res. 1999 Jan 16;816(1):99-110. doi: 10.1016/s0006-8993(98)01083-x.
The synaptic localization of molecular chaperones, heat shock cognate protein 70 (Hsc70) and Hsp40, was investigated immunohistochemically in the normal rat brain. Postsynaptic density (PSD) fractions contained a constitutive form of HSP70, heat shock cognate protein 70 (Hsc70 or p73) but not inducible form of HSP70 (p72). The immunoreactivities of Hsc70 (p73) were distributed throughout the rat brain, in neuronal somata, dendrites and axons. Their immunoreactivity in neurons was localized in the cytoplasmic matrix, dendrites, and spines at the electron microscopic level. Presynaptic terminals, but less frequently than postsynaptic staining, were also reactive. Postsynaptic areas immediately beneath the synaptic contact or PSDs were immunoreactive for Hsc70. The Hsp40 was highly concentrated in PSD fractions. The staining of Hsp40 immunoreactivity was punctate and distributed widely in the brain. Hsp40 immunoreactivity was localized in dendritic spines, especially in the subsynaptic web, with weak staining of PSDs at the electron microscopic level. Double immunofluorescent staining and confocal microscopy revealed that Hsc70 and Hsp40 were co-localized on somata and neuronal processes of cultured cerebral neurons, on which synaptophysin immunoreactive spots were scattered. These results suggest that Hsp40 and Hsc70 are co-localized at postsynaptic sites and postsynaptic chaperone activity may be mediated by these two heat shock proteins.
采用免疫组织化学方法，研究了分子伴侣热休克同源蛋白70（Hsc70）和Hsp40在正常大鼠脑内的突触定位。突触后致密物（PSD）组分中含有组成型HSP70，即热休克同源蛋白70（Hsc70或p73），但不含有诱导型HSP70（p72）。Hsc70（p73）的免疫反应性分布于大鼠全脑，包括神经元胞体、树突和轴突。在电子显微镜水平，其在神经元中的免疫反应性定位于细胞质基质、树突和棘突。突触前终末也有反应，但不如突触后染色频繁。突触接触下方紧邻的突触后区域或PSD对Hsc70呈免疫反应性。Hsp40高度集中于PSD组分中。Hsp40免疫反应性染色呈点状，广泛分布于脑内。在电子显微镜水平，Hsp40免疫反应性定位于树突棘，尤其是突触下网，而PSD染色较弱。双重免疫荧光染色和共聚焦显微镜检查显示，Hsc70和Hsp40在培养的大脑神经元的胞体和神经突起上共定位，突触素免疫反应性斑点散在其上。这些结果表明，Hsp40和Hsc70在突触后位点共定位，突触后伴侣活性可能由这两种热休克蛋白介导。
