The small muscle protein, X-linked (SMPX) gene encodes a cytoskeleton-associated protein, highly expressed in both cardiac and skeletal muscles, as well as in fetal inner ears, with suggested roles as mechanotransductor. Recently, several mutations in the SMPX gene have been associated with X-chromosomal progressive deafness in human. However, very little information is known concerning the roles of SMPX, and no in-vivo models are currently available. Therefore, we characterized the zebrafish ortholog of SMPX to pave the way towards the establishment of a biotool for future functional studies. Despite the genome duplication occurred in the ancestry of teleosts, zebrafish retain only one copy of smpx which shares a high degree of similarity with the mammalian counterpart in terms of genomic organization, syntenic map, and encoded protein. RT-PCR, as well as whole-mount in-situ hybridization and immunofluorescence analyses, revealed that smpx is expressed in several embryonic areas starting from the 4-somite stage. Specifically, smpx mRNA marked the Kupffer's vesicle (KV), the somites, the myocardium, the hair cells of the anterior and the posterior macula of the inner ear, the pronephric ducts, and the muscles of the branchial arches, eyes and pectoral fins. According to our data, zebrafish smpx expression pattern closely resembles that observed in mouse and human, supporting the notion that zebrafish might represent a suitable in-vivo model to disclose the cellular and molecular mechanisms underlying the involvement of SMPX in development and disease.

的小肌肉蛋白，X-连锁（SMPX）基因编码细胞骨架相关的蛋白质，在心脏和骨骼肌中高表达，以及在胎内耳以及建议的角色mechanotransductor。最近，SMPX基因的一些突变与人类X染色体进行性聋相关。但是，关于SMPX的作用的信息知之甚少，目前尚无体内模型。因此，我们表征了SMPX的斑马鱼直系同源物，为建立用于未来功能研究的生物工具铺平了道路。尽管基因组重复发生在硬骨鱼的祖先，但斑马鱼仅保留了一份smpx拷贝在基因组组织，同义图谱和编码蛋白方面，它与哺乳动物对应物具有高度相似性。RT-PCR以及完整的原位杂交和免疫荧光分析表明，smpx在从4个重金属阶段开始的几个胚胎区域表达。具体而言，smpx mRNA标记了库普弗氏小泡（KV），腹节，心肌，内耳前，后黄斑的毛细胞，前肾管道以及branch弓，眼和胸鳍的肌肉。根据我们的数据，斑马鱼的smpx表达模式与在小鼠和人类中观察到的模式非常相似，从而支持了斑马鱼可能代表一种合适的观点。体内模型揭示SMPX参与发育和疾病的细胞和分子机制。