De León M, Nahin R L, Mendoza M E, Ruda M A
Neurobiology and Anesthesiology Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892.
J Neurosci Res. 1994 Jun 1;38(2):167-81. doi: 10.1002/jnr.490380207.
SR13/PMP-22 is a protein that was identified after screening a sciatic nerve cDNA library. Our study focused on comparing the level and pattern of expression of SR13/PMP-22 protein and RNA. Northern blot analysis revealed that although SR13/PMP-22 mRNA was present in all nervous tissues and cells studied, levels were at least seven fold higher in the sciatic nerve and the spinal cord. During sciatic nerve postnatal development and maturation, the SR13/PMP-22 mRNA was detected at 2 days after birth, reached a maximal level at day 24, and decreased to 1/3 of the maximum in adult animals. Nerve transection reduced the level of SR13/PMP-22 mRNA to less than 5% in the segment distal to the nerve injury. Experiments using in situ hybridization localized the SR13/PMP-22 mRNA in Schwann cells. Schwann cells present in the vicinity or distal to the nerve cut repressed the signal for the message. In situ hybridization experiments also demonstrated that dorsal root ganglia satellite cells contained the message for SR13/PMP-22. The SR13/PMP-22 antisera used in our study showed a complex pattern of staining. As expected, the SR13/PMP-22 antibody peptide 1 immunoreacted with the sciatic nerve sheath. However, immunocytochemistry of the dorsal root ganglia revealed that the staining was contained in the neuron's cell body and processes and also in satellite cells. We also identified immunoreactive cell bodies and fibers in the spinal cord dorsal horn. Tissue culture studies demonstrated that SR13/PMP-22 mRNA is induced in NGF treated PC12 but not in C6 glioma cell lines grown under experimental conditions that stimulated cell growth arrest. Our experiments suggest that SR13/PMP-22 may have some other function(s) in addition to its hypothesized role in peripheral myelination.
SR13/PMP - 22是一种在筛选坐骨神经cDNA文库后鉴定出的蛋白质。我们的研究重点是比较SR13/PMP - 22蛋白和RNA的表达水平及模式。Northern印迹分析显示，尽管SR13/PMP - 22 mRNA存在于所有研究的神经组织和细胞中，但在坐骨神经和脊髓中的水平至少高7倍。在坐骨神经出生后的发育和成熟过程中，出生后2天可检测到SR13/PMP - 22 mRNA，在第24天达到最高水平，在成年动物中降至最高水平的1/3。神经横断使神经损伤远端节段的SR13/PMP - 22 mRNA水平降至不足5%。原位杂交实验将SR13/PMP - 22 mRNA定位在施万细胞中。神经切断附近或远端的施万细胞抑制了该信息的信号。原位杂交实验还表明背根神经节卫星细胞含有SR13/PMP - 22的信息。我们研究中使用的SR13/PMP - 22抗血清显示出复杂的染色模式。正如预期的那样，SR13/PMP - 22抗体肽1与坐骨神经鞘发生免疫反应。然而，背根神经节的免疫细胞化学显示，染色存在于神经元的细胞体、突起以及卫星细胞中。我们还在脊髓背角中鉴定出免疫反应性细胞体和纤维。组织培养研究表明，在神经生长因子处理的PC12细胞中可诱导SR13/PMP - 22 mRNA表达，但在实验条件下刺激细胞生长停滞的C6胶质瘤细胞系中则不会。我们的实验表明，SR13/PMP - 22除了在周围髓鞘形成中的假定作用外，可能还有其他一些功能。
