Bartsch S, Bartsch U, Dörries U, Faissner A, Weller A, Ekblom P, Schachner M
Department of Neurobiology, Swiss Federal Institute of Technology, Zürich, Switzerland.
J Neurosci. 1992 Mar;12(3):736-49. doi: 10.1523/JNEUROSCI.12-03-00736.1992.
Since tenascin may influence neuronal cell development, we studied its expression pattern using immunocytochemistry, in situ hybridization, Northern blot analysis, and immunochemistry in the developing and adult mouse cerebellar cortex. Tenascin immunoreactivity was detectable in all layers of the developing cerebellar cortex. In the external granular layer, only the radially oriented processes of Golgi epithelial cells were immunoreactive, whereas the densely packed cell bodies were immunonegative. Tenascin was hardly detectable at contact sites between migrating granule cells and processes of Golgi epithelial cells. Axons of granule cells in the molecular layer were immunoreactive, whereas their cell bodies in the internal granular layer lacked detectable levels of tenascin. By in situ hybridization, only Golgi epithelial cells and astrocytes of the internal granular layer and prospective white matter, but not nerve cells, could be shown to synthesize detectable levels of tenascin mRNA in the developing mouse cerebellar cortex. Thus, tenascin in the cerebellar cortex seems to be a glia-derived molecule that becomes adsorbed to neuronal surfaces in a topographically restricted pattern in situ. Levels of tenascin protein and mRNA decreased significantly with increasing age. In the adult, tenascin immunoreactivity was weak and mainly restricted to the molecular layer and tenascin mRNA was confined to Golgi epithelial cells, indicative for a functional heterogeneity in differentiated cerebellar astrocytes. Quantitative immunoblot analysis revealed that the 225 and 240 kDa components of tenascin were developmentally downregulated at a faster rate than the 190 and 200 kDa components, corresponding to the faster downregulation of the 8 kilobase (kb) mRNA species compared to the 6 kb mRNA species as revealed by Northern blot analysis. These observations indicate a differentially regulated expression of the tenascin components. We hypothesize that glia-derived tenascin modifies the functional properties of nerve cell surfaces and that tenascin is involved in such different morphogenetic events as neurite growth and oligodendrocyte distribution.
由于腱生蛋白可能影响神经元细胞发育，我们运用免疫细胞化学、原位杂交、Northern印迹分析以及免疫化学方法，研究了其在发育中和成年小鼠小脑皮质中的表达模式。在发育中的小脑皮质各层均能检测到腱生蛋白免疫反应性。在外部颗粒层，仅高尔基上皮细胞呈放射状排列的突起有免疫反应性，而紧密排列的细胞体则无免疫反应。在迁移的颗粒细胞与高尔基上皮细胞的突起之间的接触部位，几乎检测不到腱生蛋白。分子层中颗粒细胞的轴突有免疫反应性，而其位于内部颗粒层的细胞体则未检测到可检测水平的腱生蛋白。通过原位杂交发现，在发育中的小鼠小脑皮质中，只有内部颗粒层和预期白质中的高尔基上皮细胞及星形胶质细胞，而非神经细胞，能合成可检测水平的腱生蛋白mRNA。因此，小脑皮质中的腱生蛋白似乎是一种由神经胶质细胞衍生的分子，它以一种在原位受地形限制的模式吸附于神经元表面。腱生蛋白蛋白和mRNA水平随年龄增长显著降低。在成年小鼠中，腱生蛋白免疫反应性较弱，主要局限于分子层，腱生蛋白mRNA则局限于高尔基上皮细胞，这表明分化的小脑星形胶质细胞存在功能异质性。定量免疫印迹分析显示，腱生蛋白的225和240 kDa成分在发育过程中的下调速度比190和200 kDa成分更快，这与Northern印迹分析显示的8千碱基（kb）mRNA种类相比6 kb mRNA种类下调更快相对应。这些观察结果表明腱生蛋白各成分的表达受到差异调节。我们推测，神经胶质细胞衍生的腱生蛋白会改变神经细胞表面的功能特性，且腱生蛋白参与了诸如神经突生长和少突胶质细胞分布等不同的形态发生事件。
