Expression and functional characterization of Smyd1a in myofibril organization of skeletal muscles.
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.


RESULTS
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.


CONCLUSIONS
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.
Institute of Marine and Environmental Technology, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America ; School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangdong, China.
Jie
J
Gao
Institute of Marine and Environmental Technology, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
Junling
J
Li
Institute of Marine and Environmental Technology, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
Bao-Jun
BJ
Li
Department of Biochemistry, Tel-Aviv University, Tel-Aviv, Israel.
Ezra
E
Yagil
Department of Bioengeneering and Environmental Science, Changsha University, Hunan, China.
Jianshe
J
Zhang
Institute of Marine and Environmental Technology, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
Shao Jun
SJ
Du
D000818:Animals; D030801:Animals, Genetically Modified / Q000235:genetics / Q000254:growth & development; D015153:Blotting, Western; D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D011495:Histone-Lysine N-Methyltransferase / Q000502:physiology*; D017403:In Situ Hybridization; D051379:Mice; D009024:Morphogenesis; D024510:Muscle Development; D009124:Muscle Proteins / Q000235:genetics* / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D009210:Myofibrils / Q000378:metabolism*; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D019076:Transgenes / Q000502:physiology; D015027:Zebrafish / Q000235:genetics* / Q000254:growth & development; D029961:Zebrafish Proteins / Q000502:physiology*
D004268:DNA-Binding Proteins; D009124:Muscle Proteins; D012333:RNA, Messenger; C096485:Smyd1 protein, mouse; D014157:Transcription Factors; D029961:Zebrafish Proteins; D011495:Histone-Lysine N-Methyltransferase; C510871:SmyD1a protein, zebrafish