Huot M E, Mazroui R, Leclerc P, Khandjian E W
Unité de Recherche en Génétique Humaine et Moléculaire, Hôpital St. François d'Assise du CHUQ, 10, rue de l'Espinay, Québec G1L 3L5, Canada.
Hum Mol Genet. 2001 Nov 15;10(24):2803-11. doi: 10.1093/hmg/10.24.2803.
Fragile X mental retardation 1 protein (FMRP) is the archetype of a class of cytoplasmic mRNA-binding proteins that includes the fragile X-related 1 and 2 proteins (FXR1P and FXR2P). Whereas absence of FMRP is the cause of fragile X syndrome, it is not known if FXR1P and FXR2P are associated with any pathology. It is also still elusive whether these homologous proteins can partially compensate for the absence of FMRP in the case of the fragile X syndrome. FXR1 is widely expressed in mammals and its expression pattern is complex since several mRNA variants and protein isoforms are detected. In mouse, we observed that the highest level of FXR1 is found in the adult testis. This tissue is an exception, since all known FXR1P isoforms, some of which have been considered as tissue specific, are detected in it. In young animals, changes in mRNA-spliced variants and their corresponding protein isoforms occur during spermatogenesis. Using biochemical, immunohistochemical and electron microscopic techniques, we show that FXR1P is associated with microtubule elements. Since the cytoskeletal framework is implicated in cellular plasticity as well as in mRNA transport, we propose new possibilities for the function(s) of the FXR proteins.
脆性X智力低下1蛋白（FMRP）是一类细胞质mRNA结合蛋白的原型，这类蛋白包括脆性X相关蛋白1和2（FXR1P和FXR2P）。虽然FMRP的缺失是脆性X综合征的病因，但尚不清楚FXR1P和FXR2P是否与任何病理状况相关。在脆性X综合征的情况下，这些同源蛋白是否能够部分补偿FMRP的缺失也仍然不清楚。FXR1在哺乳动物中广泛表达，并且由于检测到几种mRNA变体和蛋白质异构体，其表达模式较为复杂。在小鼠中，我们观察到FXR1的最高水平出现在成年睾丸中。这个组织是个例外，因为在其中检测到了所有已知的FXR1P异构体，其中一些被认为是组织特异性的。在幼年动物中，mRNA剪接变体及其相应的蛋白质异构体在精子发生过程中会发生变化。使用生化、免疫组织化学和电子显微镜技术，我们表明FXR1P与微管元件相关。由于细胞骨架框架与细胞可塑性以及mRNA运输有关，我们提出了FXR蛋白功能的新可能性。
