Department of Pharmacology, Faculty of Medicine, University of Miyazaki.
Division of Oral and Maxillofacial Surgery, Department of Medicine of Sensory and Motor Organs, Faculty of Medicine, University of Miyazaki.
Cell Struct Funct. 2024 Nov 7;49(2):111-122. doi: 10.1247/csf.24044. Epub 2024 Oct 10.
The sarcomere is the contractile unit of striated muscle and is composed of actin and myosin filaments. There is increasing evidence to support that actin assembly mediated by Fhod3, a member of the formin family of proteins, is critical for sarcomere formation and maintenance in cardiac muscle. Fhod3, which is abundantly expressed in the heart, localizes to the center of sarcomeres and contributes to the regulation of the cardiac function, as evidenced by the fact that mutations in Fhod3 cause cardiomyopathy. However, the role of Fhod3 in skeletal muscle, another type of striated muscle, is unclear. We herein show that Fhod3 is expressed in the tongue at both mRNA and protein levels, although in smaller amounts than in the heart. To determine the physiological role of Fhod3 expressed in the tongue, we generated embryos lacking Fhod3 in the tongue. The tongue tissue of the Fhod3-depleted embryos did not show any significant structural defects, suggesting that Fhod3 is dispensable for normal development of the mouse tongue. Unexpectedly, the immunostaining analysis revealed the absence of specific sarcomeric signals for Fhod3 in the wild-type tongue when compared to the Fhod3-depleted tongue as a negative control, despite the use of antibodies that had previously been validated by immunostaining of heart tissues. Taken together, although Fhod3 protein is expressed at a significant level in the tongue, Fhod3 in the tongue does not appear to exhibit the same sarcomeric pattern as observed in the heart, suggesting a different role for Fhod3 in the tongue muscles.Key words: actin, formin, sarcomere, striated muscle.
肌节是横纹肌的收缩单位，由肌动蛋白和肌球蛋白丝组成。越来越多的证据支持，由形成蛋白家族成员 Fhod3 介导的肌动蛋白组装对于心肌肌节的形成和维持至关重要。Fhod3 在心脏中大量表达，定位于肌节的中心，有助于调节心脏功能，这一事实表明 Fhod3 的突变会导致心肌病。然而，Fhod3 在另一种横纹肌——骨骼肌中的作用尚不清楚。我们在此表明，Fhod3 在舌组织中以 mRNA 和蛋白质水平表达，尽管表达量比心脏中少。为了确定在舌组织中表达的 Fhod3 的生理作用，我们生成了在舌组织中缺失 Fhod3 的胚胎。Fhod3 缺失的胚胎的舌组织没有显示出任何明显的结构缺陷，这表明 Fhod3 对于小鼠舌的正常发育不是必需的。出乎意料的是，免疫染色分析显示，与作为阴性对照的 Fhod3 缺失胚胎的舌组织相比，野生型舌组织中缺乏特定的肌节信号，尽管使用的抗体以前已经通过心脏组织的免疫染色进行了验证。总之，尽管 Fhod3 蛋白在舌组织中以显著水平表达，但 Fhod3 在舌组织中似乎没有表现出与心脏中观察到的相同的肌节模式，这表明 Fhod3 在舌肌中的作用不同。关键词：肌动蛋白、形成蛋白、肌节、横纹肌。
