DIFFERENTIATION-ASSOCIATED SWITCHES IN PROTEIN 4.1 EXPRESSION - SYNTHESIS OF MULTIPLE STRUCTURAL ISOFORMS DURING NORMAL HUMAN ERYTHROPOIESIS
DIFFERENTIATION-ASSOCIATED SWITCHES IN PROTEIN 4.1 EXPRESSION - SYNTHESIS OF MULTIPLE STRUCTURAL ISOFORMS DURING NORMAL HUMAN ERYTHROPOIESIS
复制标题
DOI：
10.1172/jci116189
复制
发表时间：
1993-01-01
影响因子：
15.9
通讯作者：
MOHANDAS, N
中科院分区：
文献类型：
--
作者：
CHASIS, JA;COULOMBEL, L;MOHANDAS, N
红细胞分化伴随着形态学和膜机械性质的显著改变，这在很大程度上是由于膜骨架蛋白网络的重组。80 kD蛋白4.1是这种膜骨架的重要组织成分。最近，已经认识到4.1的多种结构同种型由单个基因通过选择性前体mRNA剪接编码，并且上游ATG可以被剪接并用于高分子量4.1的翻译。我们正在探索蛋白4.1结构中的分化相关开关在膜重组中起重要作用的假设。为了研究正常人分化过程中4.1基因表达的变化，我们分析了不同发育阶段的4.1蛋白和mRNA结构。使用免疫荧光显微镜，我们观察到高分子量4.1亚型preproerythroblasts生产点状，主要是细胞质染色与强烈的荧光核周区，而成熟的红细胞表达非常少的高分子量4.1。同种型含有替代表达的102个核苷酸的外显子附近的COOH末端是丰富的preproerythroblast和成熟细胞，但产生了点状分布的荧光在整个preproerythroblast和强烈的膜相关的荧光在红细胞。通过聚合酶链反应和核酸酶保护试验对RNA的表征揭示了血影蛋白-肌动蛋白结合结构域中前mRNA剪接的分化相关开关。由于该结构域在调节膜材料特性中起着关键作用，我们推测这种开关可能对红细胞生成过程中骨骼网络的重组至关重要。我们的结论是，4.1亚型的差异表达和差异定位在红细胞生成过程中，这个亚型家族可能有不同的功能在终末分化。
Erythroid differentiation is accompanied by dramatic alterations in morphology and membrane mechanical properties resulting, in large part, from reorganization of the membrane skeletal protein network. The 80-kD protein 4.1 is an important organizational component of this membrane skeleton. Recently, it has been recognized that multiple structural isoforms of 4.1 are encoded by a single gene via alternative pre-mRNA splicing, and that an upstream ATG can be spliced in and used for translation of high molecular weight 4.1. We are exploring the hypothesis that differentiation-associated switches in protein 4.1 structure play an important role in membrane reorganization.To study changes in 4.1 gene expression during normal human differentiation, we analyzed 4.1 protein and mRNA structure at various developmental stages. Using immunofluorescence microscopy, we observed high molecular weight 4.1 isoforms in preproerythroblasts producing punctate, predominantly cytoplasmic staining with a perinuclear area of intense fluorescence, while mature red cells expressed very little high molecular weight 4.1. Isoforms containing an alternatively expressed 102-nucleotide exon near the COOH terminus were abundant in both preproerythroblasts and mature cells but produced a punctate distribution of fluorescence over the entire preproerythroblast and intense membrane-associated fluorescence in the erythrocyte. Characterization of RNA by polymerase chain reaction and nuclease protection assays revealed a differentiation-associated switch in pre-mRNA splicing in the spectrin-actin binding domain. Since this domain plays a critical role in regulating membrane material properties, we speculate that this switch may be crucial to reorganization of the skeletal network during erythropoiesis. We conclude that 4.1 isoforms are differentially expressed and differentially localized during erythropoiesis, and that this isoform family is likely to have diverse functions during terminal differentiation.