THE EXPRESSION AND POSTTRANSLATIONAL MODIFICATION OF A NEURON-SPECIFIC BETA-TUBULIN ISOTYPE DURING CHICK EMBRYOGENESIS
THE EXPRESSION AND POSTTRANSLATIONAL MODIFICATION OF A NEURON-SPECIFIC BETA-TUBULIN ISOTYPE DURING CHICK EMBRYOGENESIS
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DOI：
10.1002/cm.970170207
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发表时间：
1990-01-01
影响因子：
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通讯作者：
FRANKFURTER, A
中科院分区：
文献类型：
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作者：
LEE, MK;TUTTLE, JB;FRANKFURTER, A
五种β-微管蛋白亚型在鸡脑发育过程中有不同的表达。这些同工型中的一种由基因cβ4编码，并被归入指定为Class III(βIII)的同型家族。在高等脊椎动物的神经系统中，βIII完全由神经元合成。使用βIII特异的单抗来确定在鸡胚胎发育过程中表达Cβ4的时间、βIII的细胞定位以及通过等电聚焦可以分解成的电荷变体(异构体)的数量。在Western blotts上，在12-13阶段首先可以检测到βIII。此后，大脑中βIII的相对丰度稳步增加，显然与神经分化率有关。在大龄胚胎(第10-14天)和孵化幼体的非神经组织提取液中未检测到该同种类型。双向凝胶电泳法(2D-PAGE)分离的蛋白质蛋白质印迹显示，在神经发育过程中，βIII亚型的数量从1个增加到3个。这一证据表明，βIII是发育调节的多位点翻译后修饰的底物。免疫细胞化学研究表明，虽然cβ4的表达主要限于神经系统，但它在一些胚胎结构中是瞬时表达的。更重要的是，在神经系统中，免疫反应细胞主要位于神经上皮细胞的非增殖性边缘区域。主要含有有丝分裂的神经母细胞的区域几乎没有染色。这种定位模式表明，cβ4的表达发生在末端有丝分裂期间或紧随其后，并提示βIII在神经元早期分化和轴突生长过程中可能具有独特的作用。
Five .beta.-tubulin isotypes are expressed differentially during chicken brain development. One of these isotypes is encoded by the gene c.beta.4 and has been assigned to an isotypic family designated as Class III (.beta.III). In the nervous system of higher vertebrates, .beta.III is synthesized exclusively by neurons. A .beta.III-specific monoclonal antibody was used to determine when during chick embryogenesis c.beta.4 is expressed, the cellular localization of .beta.III, and the number of charge variants (isoforms) into which .beta.III can be resolved by isoelectric focusing. On Western blots, .beta.III is first detectable at stages 12-13. Thereafter, the relative abundance of .beta.III in brain increases steadily, apparently in conjunction with the rate of neural differentiation. The isotype was not detectable in non-neural tissue extracts from older embryos (days 10-14) and hatchlings. Western blots of protein separated by two-dimensional gel electrophoresis (2D-PAGE) reveal that the number of .beta.III isoforms increases from one to three during neural development. This evidence indicates that .beta.III is a substrate for developmentally regulated, multiple-site posttranslational modification. Immunocytochemical studies reveal that while c.beta.4 expression is restricted predominantly to the nervous system, it is transiently expressed in some embryonic structures. More importantly, in the nervous system, immunoreactive cells were located primarily in the non-proliferative marginal zone of the neural epithelia. Regions containing primarily mitotic neuroblasts were virtually unstained. This localization pattern indicates that c.beta.4 expression occurs either during or immediately following terminal mitosis, and suggests that .beta.III may have a unique role during early neuronal differentiation and neurite outgrowth.