Key result
Knockdown of smyd1a and smyd1b together resulted in a complete disruption of myofibril organization in skeletal muscles of zebrafish embryos, a phenotype stronger than knockdown of either gene alone.
Smyd1a and Smyd1b share redundant biological activity in myofibril assembly in zebrafish embryos, with Smyd1b playing the dominant role.
Smyd1a may compensate for Smyd1b loss in zebrafish muscle; leaves open whether dual targeting is needed in mammalian models.
BACKGROUND: Smyd1, the founding member of the Smyd family including Smyd-1, 2, 3, 4 and 5, is a SET and MYND domain containing protein that plays a key role in myofibril assembly in skeletal and cardiac muscles. Bioinformatic analysis revealed that zebrafish genome contains two highly related smyd1 genes, smyd1a and smyd1b. Although Smyd1b function is well characterized in skeletal and cardiac muscles, the function of Smyd1a is, however, unknown. METHODOLOGY/PRINCIPAL FINDINGS: To investigate the function of Smyd1a in muscle development, we isolated smyd1a from zebrafish, and characterized its expression and function during muscle development via gene knockdown and transgenic expression approaches. The results showed that smyd1a was strongly expressed in skeletal muscles of zebrafish embryos. Functional analysis revealed that knockdown of smyd1a alone had no significant effect on myofibril assembly in zebrafish skeletal muscles. However, knockdown of smyd1a and smyd1b together resulted in a complete disruption of myofibril organization in skeletal muscles, a phenotype stronger than knockdown of smyd1a or smyd1b alone. Moreover, ectopic expression of zebrafish smyd1a or mouse Smyd1 transgene could rescue the myofibril defects from the smyd1b knockdown in zebrafish embryos. CONCLUSION/SIGNIFICANCE: Collectively, these data indicate that Smyd1a and Smyd1b share similar biological activity in myofibril assembly in zebrafish embryos. However, Smyd1b appears to play a major role in this process.
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Gao et al. (2014) studied Muscle development and myofibril organization. smyd1a and smyd1b knockdown vs. Control morpholino or single gene knockdown was evaluated on Myofibril assembly and sarcomere organization. Knockdown of smyd1a and smyd1b together resulted in a complete disruption of myofibril organization in skeletal muscles of zebrafish embryos, a phenotype stronger than knockdown of either gene alone.
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