Smyd1b_tv1, a key regulator of sarcomere assembly, is localized on the M-line of skeletal muscle fibers.
Smyd1b_tv1, a key regulator of sarcomere assembly, is localized on the M-line of skeletal muscle fibers.
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DOI：
10.1371/journal.pone.0028524
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发表时间：
2011
期刊：
影响因子：
3.7
通讯作者：
Du SJ
中科院分区：
文献类型：
--
作者：
Li H;Xu J;Bian YH;Rotllant P;Shen T;Chu W;Zhang J;Schneider M;Du SJ
Smyd 1b是Smyd家族的成员，在肌原纤维发生期间的肌节组装中起关键作用。Smyd 1b基因编码两种剪接异构体smyd1b_tv1和smyd1b_tv2，它们在骨骼肌和心肌中表达，并在斑马鱼胚胎骨骼肌的肌原纤维发生中起重要作用。为了更好地了解Smyd 1b在肌原纤维发生中的功能，我们分析了Smyd1b_tv1和Smyd1b_tv2在表达myc标记的Smyd1b_tv1或Smyd1b_tv2的转基因斑马鱼中的亚细胞定位。结果表明，在肌细胞分化过程中，它们的亚细胞定位呈动态变化。Smyd1b_tv1和Smyd1b_tv2主要定位于早期斑马鱼胚胎成肌细胞和肌管的胞浆中。然而，在成熟的肌纤维，Smyd1b_tv1，并在小程度上Smyd1b_tv2，表现出肌节定位。与肌节标记的双重染色显示Smyd1b_tv1定位于M线。在表达Smyd1b_tv1-GFP或Smyd1b_tv2-GFP融合蛋白的斑马鱼胚胎中证实了肌节定位。与Smyd1b_tv1相比，Smyd1b_tv2的肌节定位较弱。Smyd1b_tv1与Smyd1b_tv2的不同之处在于由外显子5编码的13个氨基酸插入，这表明13个氨基酸插入内的一些残基可能对Smyd1b_tv1的强肌节定位至关重要。与其他脊椎动物的Smyd1b_tv1同源序列比较发现，在13个氨基酸的插入中有几个高度保守的残基（Phe 223，His 224和Gln 226）和两个潜在的磷酸化位点（Thr 221和Ser 225）。为了确定这些残基是否参与增加Smyd1b_tv1的肌节定位，我们将这些残基突变为丙氨酸。用丙氨酸取代Phe 223或Ser 225显著降低Smyd1b_tv1的肌节定位。相比之下，其他替代品没有效果。此外，用苏氨酸（S225 T）取代Ser 225保留了Smyd1b_tv1的强肌节定位。总之，这些数据表明，Phe 223和Ser 225是Smyd1b_tv1的M线定位所必需的。
Smyd1b is a member of the Smyd family that plays a key role in sarcomere assembly during myofibrillogenesis. Smyd1b encodes two alternatively spliced isoforms, smyd1b_tv1 and smyd1b_tv2, that are expressed in skeletal and cardiac muscles and play a vital role in myofibrillogenesis in skeletal muscles of zebrafish embryos. To better understand Smyd1b function in myofibrillogenesis, we analyzed the subcellular localization of Smyd1b_tv1 and Smyd1b_tv2 in transgenic zebrafish expressing a myc-tagged Smyd1b_tv1 or Smyd1b_tv2. The results showed a dynamic change of their subcellular localization during muscle cell differentiation. Smyd1b_tv1 and Smyd1b_tv2 were primarily localized in the cytosol of myoblasts and myotubes at early stage zebrafish embryos. However, in mature myofibers, Smyd1b_tv1, and to a small degree of Smyd1b_tv2, exhibited a sarcomeric localization. Double staining with sarcomeric markers revealed that Smyd1b_tv1was localized on the M-lines. The sarcomeric localization was confirmed in zebrafish embryos expressing the Smyd1b_tv1-GFP or Smyd1b_tv2-GFP fusion proteins. Compared with Smyd1b_tv1, Smyd1b_tv2, however, showed a weak sarcomeric localization. Smyd1b_tv1 differs from Smyd1b_tv2 by a 13 amino acid insertion encoded by exon 5, suggesting that some residues within the 13 aa insertion may be critical for the strong sarcomeric localization of Smyd1b_tv1. Sequence comparison with Smyd1b_tv1 orthologs from other vertebrates revealed several highly conserved residues (Phe223, His224 and Gln226) and two potential phosphorylation sites (Thr221 and Ser225) within the 13 aa insertion. To determine whether these residues are involved in the increased sarcomeric localization of Smyd1b_tv1, we mutated these residues into alanine. Substitution of Phe223 or Ser225 with alanine significantly reduced the sarcomeric localization of Smyd1b_tv1. In contrast, other substitutions had no effect. Moreover, replacing Ser225 with threonine (S225T) retained the strong sarcomeric localization of Smyd1b_tv1. Together, these data indicate that Phe223 and Ser225 are required for the M-line localization of Smyd1b_tv1.
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影响因子：
3.7
作者：
Codina M;Li J;Gutiérrez J;Kao JP;Du SJ
通讯作者：
Du SJ
DOI：
10.1073/pnas.0707330105
发表时间：
2008-01-15
影响因子：
11.1
作者：
Du, Shao Jun;Li, Huiqing;Zhong, Yongwang
通讯作者：
Zhong, Yongwang
影响因子：
4
作者：
Just, Steffen;Meder, Benjamin;Rottbauer, Wolfgang
通讯作者：
Rottbauer, Wolfgang
DOI：
10.1073/pnas.0509503103
发表时间：
2006-02-21
影响因子：
11.1
作者：
Tan, XG;Rotllant, J;Du, SJ
通讯作者：
Du, SJ
影响因子：
56.9
作者：
PAIK, WK;KIM, S
通讯作者：
KIM, S