Paden C M, Zhou X, Watt J A, Burton R, Pickett J, Oblinger M M
Department of Biology, Montana State University, Bozeman 59717, USA.
J Comp Neurol. 1995 Nov 20;362(3):368-84. doi: 10.1002/cne.903620306.
A comprehensive survey of class I alpha-tubulin (alpha 1) and class II beta-tubulin (beta II) mRNAs was performed using in situ hybridization in order to determine the extent of continued expression of these immature tubulin isotype mRNAs in the adult rat brain. Qualitatively similar distributions of the two isotype mRNAs were observed, with marked variations in hybridization intensity of both probes apparent across different brain regions. Neurons in a wide variety of structures throughout the brain exhibited intense hybridization signals. While the presence of large numbers of neurons with a moderate hybridization intensity could account for the relatively high level of total binding in some regions such as the cerebellar and dentate granule layers, in most cases higher regional mRNA levels reflected greater hybridization intensity per neuron. Little variability in hybridization intensity was typically seen between individual cells within specific nuclei throughout the brain. The presence of occasional intensely labeled neurons scattered throughout the basal ganglia provided the most striking exception to this pattern. While no qualitative differences between the distributions of alpha 1-tubulin and beta II-tubulin mRNAs were observed, consistent differences in the relative intensity of hybridization for alpha 1-tubulin versus beta II-tubulin mRNA were apparent in a few brain regions. Expression by glia did not appear to contribute significantly to detectable levels of either alpha 1-tubulin or beta II-tubulin mRNA. These findings suggest that continued expression of growth-associated tubulin isotype mRNAs may have functional significance in specific neuronal populations of the adult brain. Partial overlap between the distributions of alpha 1- and beta II-tubulin mRNAs and that of GAP-43 mRNA is discussed, as are potential roles for growth-associated tubulin gene expression in supporting cytoskeletal turnover, reactive axonal growth, and dendritic remodeling in the adult brain.
为了确定这些未成熟微管蛋白同种型mRNA在成年大鼠脑中持续表达的程度，我们使用原位杂交技术对I类α-微管蛋白（α1）和II类β-微管蛋白（βII）mRNA进行了全面调查。观察到两种同种型mRNA在定性上具有相似的分布，两种探针的杂交强度在不同脑区存在明显差异。全脑各种结构中的神经元均表现出强烈的杂交信号。虽然在某些区域，如小脑和齿状颗粒层，大量中等杂交强度的神经元的存在可以解释总结合水平相对较高的原因，但在大多数情况下，较高的区域mRNA水平反映了每个神经元更高的杂交强度。在全脑特定核内的单个细胞之间，杂交强度通常变化很小。偶尔散布在基底神经节中的强烈标记神经元的存在是这种模式最明显的例外。虽然未观察到α1-微管蛋白和βII-微管蛋白mRNA分布之间的定性差异，但在少数脑区，α1-微管蛋白与βII-微管蛋白mRNA杂交的相对强度存在一致差异。神经胶质细胞的表达似乎对可检测到的α1-微管蛋白或βII-微管蛋白mRNA水平没有显著贡献。这些发现表明，与生长相关的微管蛋白同种型mRNA的持续表达可能在成年脑的特定神经元群体中具有功能意义。本文讨论了α1-和βII-微管蛋白mRNA分布与GAP-43 mRNA分布之间的部分重叠，以及与生长相关的微管蛋白基因表达在支持成年脑的细胞骨架周转、反应性轴突生长和树突重塑中的潜在作用。
