Vanier Marie-Thérèse, Deck Paula, Stutzmann Jeanne, Gendry Patrick, Arnold Christiane, Dirrig-Grosch Sylvie, Kedinger Michèle, Launay Jean-François
INSERM U.381, Strasbourg, France.
Cell Motil Cytoskeleton. 2003 Aug;55(4):221-31. doi: 10.1002/cm.10124.
Epithelial cell proliferation and differentiation occur concomitant with striking remodeling of the cytoskeleton. Microtubules (MTs) play important roles in these processes, during which the MTs themselves are reorganized and stabilized by microtubule-associated proteins (MAPs). Among the proteins classified as structural MAPs, E-MAP-115 (also named ensconsin) is preferentially expressed in cells of epithelial origin. The aims of this study were, first, to determine if E-MAP-115, like other MAPs, is expressed as different isoforms during differentiation and, second, to perform a detailed analysis of the expression and distribution of any E-MAP-115 variants detected in intestinal epithelial cells during their polarization/differentiation. It was our expectation that these data would help us to develop hypotheses concerning the role of this MAP in epithelial development. We report the expression of three E-MAP-115 transcripts encoding isoforms of 115, 105, and 95 kDa; two display an expression gradient inverse to the third one as Caco-2 cells progress from proliferation through the stages of differentiation. To monitor the proteins produced from each transcript, we used purified polyclonal antibodies against synthetic peptides contained within the 115, 105, and 95 kDa isoforms to assay proliferating and differentiating CaCo-2 cells. Our results indicate that the expression and MT-binding capacity of the 115, 105, and 95 kDa isoforms vary upon proliferation/differentiation of the cells. E-MAP-115 proteins colocalize with MTs in proliferative and differentiated Caco-2 cells; in vivo, they are expressed in both crypt and villus epithelial cells where they are mainly concentrated at the apical pole of the cells.
上皮细胞的增殖和分化与细胞骨架的显著重塑同时发生。微管（MTs）在这些过程中发挥重要作用，在此期间，微管自身会通过微管相关蛋白（MAPs）进行重组和稳定。在被归类为结构MAPs的蛋白质中，E-MAP-115（也称为ensconsin）优先在上皮起源的细胞中表达。本研究的目的，首先是确定E-MAP-115是否像其他MAPs一样，在分化过程中以不同的异构体形式表达；其次是对在肠上皮细胞极化/分化过程中检测到的任何E-MAP-115变体的表达和分布进行详细分析。我们期望这些数据将有助于我们提出关于这种MAP在上皮发育中作用的假设。我们报告了编码115、105和95 kDa异构体的三种E-MAP-115转录本的表达；随着Caco-2细胞从增殖阶段进入分化阶段，其中两种转录本呈现出与第三种相反的表达梯度。为了监测每个转录本产生的蛋白质，我们使用了针对115、105和95 kDa异构体中所含合成肽的纯化多克隆抗体来检测增殖和分化的CaCo-2细胞。我们的结果表明，115、105和95 kDa异构体的表达和与MT的结合能力在细胞增殖/分化时会发生变化。E-MAP-115蛋白在增殖和分化的Caco-2细胞中与MT共定位；在体内，它们在隐窝和绒毛上皮细胞中均有表达，主要集中在细胞的顶端极。
