Du Shao Jun, Rotllant Josep, Tan Xungang
Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, Maryland 21202, USA.
Dev Dyn. 2006 Dec;235(12):3306-15. doi: 10.1002/dvdy.20984.
Zebrafish SmyD1 is a SET and MYND domain-containing protein that plays an important role in myofiber maturation and muscle contraction. SmyD1 is required for myofibril organization and sarcomere assembly during myofiber maturation. Whole-mount in situ hybridization revealed that smyd1 mRNAs are specifically expressed in skeletal and cardiac muscles in zebrafish embryos. However, it is unknown if smyd1 is expressed in other striated muscles, such as cranial and fin muscles, and moreover, the regulatory elements required for its muscle-specific expression. We report here the analyses of smyd1 expression using smyd1-gfp transgenic zebrafish. smyd1-gfp transgenic zebrafish were generated using the 5.3-kb smyd1 promoter and its 5'-flanking sequence. GFP expression was found in the skeletal and cardiac muscles of smyd1-gfp transgenic embryos. GFP expression appeared stronger in slow muscles than fast muscles in transgenic zebrafish larvae. In addition, GFP expression was also detected in cranial and fin muscles of smyd1-gfp transgenic zebrafish larvae. In situ hybridization confirmed smyd1 mRNA expression in these tissues, suggesting that the expression of the smyd1-gfp transgene recapitulated that of the endogenous smyd1 gene. Deletion analysis revealed that the 0.5-kb sequence in the proximal promoter of smyd1 was essential for its muscle specificity. Together, these data indicate that smyd1 is specifically expressed in most, if not all, striated muscles, and the muscle specificity is controlled by the 5.3-kb promoter and flanking sequences.
斑马鱼SmyD1是一种含有SET和MYND结构域的蛋白质，在肌纤维成熟和肌肉收缩中发挥重要作用。在肌纤维成熟过程中，SmyD1是肌原纤维组织和肌节组装所必需的。整体原位杂交显示，smyd1 mRNA在斑马鱼胚胎的骨骼肌和心肌中特异性表达。然而，尚不清楚smyd1是否在其他横纹肌中表达，如头部和鳍部肌肉，此外，其肌肉特异性表达所需的调控元件也不清楚。我们在此报告使用smyd1 - gfp转基因斑马鱼对smyd1表达的分析。使用5.3 kb的smyd1启动子及其5'侧翼序列生成了smyd1 - gfp转基因斑马鱼。在smyd1 - gfp转基因胚胎的骨骼肌和心肌中发现了GFP表达。在转基因斑马鱼幼虫中，慢肌中的GFP表达比快肌中更强。此外，在smyd1 - gfp转基因斑马鱼幼虫的头部和鳍部肌肉中也检测到了GFP表达。原位杂交证实了这些组织中smyd1 mRNA的表达，表明smyd1 - gfp转基因的表达重现了内源性smyd1基因的表达。缺失分析表明，smyd1近端启动子中的0.5 kb序列对其肌肉特异性至关重要。总之，这些数据表明smyd1在大多数（如果不是全部）横纹肌中特异性表达，并且肌肉特异性由5.3 kb的启动子和侧翼序列控制。
