Muragaki Y, Timothy N, Leight S, Hempstead B L, Chao M V, Trojanowski J Q, Lee V M
Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
J Comp Neurol. 1995 Jun 5;356(3):387-97. doi: 10.1002/cne.903560306.
A family of tyrosine receptor kinases known collectively as trk receptors plays an essential role in signal transduction mediated by nerve growth factor and related neurotrophins. To localize the major trk receptors (trkA, B and C) in the developing and adult central (CNS) and peripheral (PNS) nervous system, we generated monoclonal antibodies (MAbs) to extracellular (MAbs E7, E13, E16, E21, E29) and intracellular (MAb I2) domains of human trkA fused to glutathione S-transferase. Several MAbs (E7, E13, E16) recognized glycosylated trkA (gp140trk and gp110trk) in Western blots, one MAb (E7) recognized non-glycosylated (p80trk) and glycosylated trkA in immunoprecipitation assays, and two MAbs (E13, E29) detected trkA on the cell surface of NIH3T3 cells transfected with a trkA cDNA. Although generated to trkA fusion proteins, this panel of MAbs also recognized trkB and trkC in flow cytometric studies of NIH3T3 cells transfected with trkB or trkC cDNAs. Thus, we used these pan-trk MAbs to probe selected regions of the CNS and PNS including the hippocampus, nucleus basalis of Meynert, cerebellum, spinal cord, and dorsal root ganglion (DRG) to localize trkA, B, and C receptors in the developing and adult human nervous system. These studies showed that trk receptors are expressed primarily by neurons and are detectable very early in the developing hippocampus, cerebellum, spinal cord, and DRG. Although the distribution and intensity of trk immunoreactivity changed with the progressive maturation of the CNS and PNS, immunoreactive trk receptors were detected in neurons of the adult human hippocampus, nucleus basalis of Meynert, cerebellum, spinal cord, and DRG. This first study of trk receptor proteins in the developing and adult human CNS and PNS documents the expression of these receptors in subsets of neurons throughout the developing and adult nervous system. Thus, although the expression of trk receptor proteins is developmentally regulated, the constitutive expression of these neurotrophin receptors by neurons in many regions of the adult human CNS and PNS implies that mature trk receptor-bearing neurons retain the ability to respond to neurotrophins long after terminal neuronal differentiation is complete.
一类统称为trk受体的酪氨酸受体激酶家族，在由神经生长因子和相关神经营养因子介导的信号转导中发挥着重要作用。为了在发育中和成年的中枢神经系统（CNS）及外周神经系统（PNS）中定位主要的trk受体（trkA、B和C），我们制备了针对与谷胱甘肽S-转移酶融合的人trkA细胞外结构域（单克隆抗体E7、E13、E16、E21、E29）和细胞内结构域（单克隆抗体I2）的单克隆抗体（MAb）。几种单克隆抗体（E7、E13、E16）在蛋白质免疫印迹中识别糖基化的trkA（gp140trk和gp110trk），一种单克隆抗体（E7）在免疫沉淀试验中识别非糖基化的（p80trk）和糖基化的trkA，两种单克隆抗体（E13、E29）在转染了trkA cDNA的NIH3T3细胞的细胞表面检测到trkA。尽管是针对trkA融合蛋白制备的，但在对转染了trkB或trkC cDNA的NIH3T3细胞进行的流式细胞术研究中，这组单克隆抗体也识别trkB和trkC。因此，我们使用这些泛trk单克隆抗体探测CNS和PNS的选定区域，包括海马体、迈内特基底核、小脑、脊髓和背根神经节（DRG），以在发育中和成年的人类神经系统中定位trkA、B和C受体。这些研究表明，trk受体主要由神经元表达，并且在发育中的海马体、小脑、脊髓和DRG中很早就可检测到。尽管随着CNS和PNS的逐渐成熟，trk免疫反应性的分布和强度发生了变化，但在成年人类海马体、迈内特基底核、小脑、脊髓和DRG的神经元中检测到了免疫反应性trk受体。这项关于发育中和成年人类CNS及PNS中trk受体蛋白的首次研究记录了这些受体在整个发育中和成年神经系统的神经元亚群中的表达。因此，尽管trk受体蛋白的表达受到发育调控，但成年人类CNS和PNS许多区域的神经元对这些神经营养因子受体的组成性表达意味着，在神经元终末分化完成很久之后, 带有成熟trk受体的神经元仍保留对神经营养因子作出反应的能力。
