人脑发育过程中髓鞘碱性蛋白基因的表达

Expression of Myelin Basic Protein Gene in the Developing Human Brain

为探索人脑髓鞘碱性蛋白（ＭＢＰ）基因表达的时空秩序与髓鞘发生和形成之间关系，采用３２Ｐ－和生物素标记鼠ＭＢＰｃＤＮＡ和地高辛标记人ＭＢＰｃＲＮＡ探针，对发育过程中人脑进行Ｎｏｒｔｈｅｒｎ斑点杂交和原位杂交研究。Ｎｏｒｔｈｅｒｎ斑点分析结果显示：１６周胎龄脑ＭＢＰｍＲＮＡ表达已明显，Ａ５９０值近２．０／μｇＲＮＡ，随发育逐渐增加，至成年其表达增至９倍（Ａ５９０值为１８／μｇＲＮＡ）。８～２５周胎龄脊髓和延脑切片以及２０、２２和２５周胎龄桥脑、中脑、丘脑、小脑和大脑切片原位杂交结果表明：在８～９周胎龄人脑脊髓前角和近延脑第四脑室底区域中，其散在细胞的核周胞浆内有ＭＢＰｍＲＮＡ表达信号，该阳性细胞比少突细胞大，而且胞浆丰富，它们究竟是神经元或胶质前体仍待鉴定。在２０周胎龄期，ＭＢＰｍＲＮＡ表达在脊髓和延脑区骤增，并沿少突细胞突起延伸呈网状；此期桥脑该基因表达已明显。

The expression of myelin basic protein (MBP) gene in the developing human brain was studied by using Northern dot blot and in situ hybridization with 32 P and biotin labeled rat MBP cDNA and Dig labeled human MBP cRNA probes so as to explore the relation of temporal and spatial expression of human MBP gene to myelinogenesis and myelination. The results of dot blot analysis showed that the expression of MBP mRNA was near 2.0 A 590 /μg of RNA in the fetal brain at 16 weeks of conceptional age, and it increased progressively with development to have 9 fold increment (18 A 590 /μg of RNA) in the adult brain. The in situ hybridization was performed with the sections of fetal spinal cord and medulla oblongata at 8 25 weeks of conceptional age, and of pons, midbrain, thalamus, cerebellum and cerebrum at 20, 22 and 25 weeks. The results indicated that the expression of MBP mRNA was found as early as 8 9 weeks and localized within the perinuclear cytoplasm of the scattered cells in the ventral horn of spinal cord and near the basis of the fourth ventricle of medulla oblongata. Whether the above mentioned labeled cells are neurons or precursors of glial cell remains to be identified because they are larger in size and have more abundant cytoplasm than oligodendrocytes. The labeling of MBP mRNA abruptly increased and spread with the processes of oligodendrocytes to form a network in spinal cord and medulla at 20 weeks; meanwhile, labeling was obvious in pons and scattering in the other brain regions examined.