Landry C F, Watson J B, Kashima T, Campagnoni A T
Mental Retardation Research Center, UCLA School of Medicine 90024.
Brain Res Mol Brain Res. 1994 Nov;27(1):1-11. doi: 10.1016/0169-328x(94)90178-3.
The unique structures of process-bearing cells in the central nervous system (CNS) present an ideal model with which to study the differential distribution of mRNA. We conducted a side-by-side examination of the intracellular distribution of nine neural mRNAs by in situ hybridization histochemistry in mammalian brain and observed four general types of mRNA distributions. (1) Some mRNA species were confined to cell somas and included those encoding the glial proteins, myelin proteolipid protein and 2'3'-cyclic nucleotide-3'-phosphodiesterase and the neuronal enzymes, neuron-specific enolase and glutamate decarboxylase-67. (2) Some mRNAs were found abundantly within the cell soma and were also located throughout cellular processes. These included myelin basic protein (MBP) mRNA, which was localized to the cell soma and myelin sheaths of oligodendrocytes, and glial fibrillary acidic protein (GFAP) mRNA, which was localized to the cell soma and processes of reactive and some non-reactive astrocytes in the adult brain and radial glia in embryonic brain. (3) Some mRNAs were found primarily in perinuclear cytoplasm but in some cells were also observed in cell processes. These included mRNAs encoding the protein kinase C/calmodulin-binding substrates, RC3 (neurogranin) and GAP-43, which were identified in the somas as well as within the proximal dendritic branches of specific forebrain neurons. (4) Some mRNAs were localized primarily within cell processes. These included MAP2 mRNA, which was identified by deep staining within dendritic fields but by only light staining within neuronal cell bodies. The data also indicated that the stage of cellular development and the regional location of a cell within the CNS had a profound influence on translocation events. MAP2 mRNA was found in the dendritic processes of most neurons but was confined to the soma of neurons in specific brainstem nuclei. MBP mRNA was confined to the perinuclear cytoplasm of immature oligodendrocytes and was then transported into the myelin sheath at a developmental stage corresponding to myelination. The distribution patterns of these mRNAs are likely to reflect the mechanism by which the protein products of these molecules are targeted within neurons and glia. In addition, mRNA movement may be influenced by cellular and regional factors not encoded solely within the structure of the translocated mRNA.
中枢神经系统（CNS）中具有突起的细胞的独特结构为研究mRNA的差异分布提供了一个理想模型。我们通过原位杂交组织化学方法，对哺乳动物脑中九种神经mRNA的细胞内分布进行了对比研究，观察到四种常见的mRNA分布类型。（1）一些mRNA种类局限于细胞体，包括那些编码胶质蛋白、髓鞘蛋白脂蛋白和2',3'-环核苷酸-3'-磷酸二酯酶的mRNA，以及神经元酶、神经元特异性烯醇化酶和谷氨酸脱羧酶-67的mRNA。（2）一些mRNA在细胞体中大量存在，并且也分布于整个细胞突起中。这些包括髓鞘碱性蛋白（MBP）mRNA，其定位于少突胶质细胞的细胞体和髓鞘；以及胶质纤维酸性蛋白（GFAP）mRNA，其定位于成体脑中反应性和一些非反应性星形胶质细胞的细胞体和突起，以及胚胎脑中的放射状胶质细胞。（3）一些mRNA主要存在于核周细胞质中，但在一些细胞中也在细胞突起中观察到。这些包括编码蛋白激酶C/钙调蛋白结合底物RC3（神经颗粒素）和GAP-43的mRNA，它们在特定前脑神经元的细胞体以及近端树突分支中被鉴定出来。（4）一些mRNA主要定位于细胞突起内。这些包括MAP2 mRNA，其在树突区域通过深染色鉴定，但在神经元细胞体内仅通过浅染色鉴定。数据还表明，细胞发育阶段以及CNS内细胞的区域位置对转运事件有深远影响。MAP2 mRNA在大多数神经元的树突突起中被发现，但局限于特定脑干核中神经元的细胞体。MBP mRNA局限于未成熟少突胶质细胞的核周细胞质中，然后在与髓鞘形成相对应的发育阶段被转运到髓鞘中。这些mRNA的分布模式可能反映了这些分子的蛋白质产物在神经元和胶质细胞内靶向定位的机制。此外，mRNA的移动可能受到并非仅由转运mRNA的结构所编码的细胞和区域因素的影响。
