Drosophila UNC-45 accumulates in embryonic blastoderm and in muscles, and is essential for muscle myosin stability
Drosophila UNC-45 accumulates in embryonic blastoderm and in muscles, and is essential for muscle myosin stability
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DOI：
10.1242/jcs.078964
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发表时间：
2011-03-01
影响因子：
4
通讯作者：
Bernstein, Sanford I.
中科院分区：
文献类型：
--
作者：
Lee, Chi F.;Melkani, Girish C.;Bernstein, Sanford I.
UNC-45是一种促进肌凝蛋白运动结构域折叠的伴侣。我们利用黑腹果蝇研究了UNC-45在肌肉发育和功能中的作用。果蝇UNC-45 （dUNC-45）在所有发育阶段均有表达。它与非肌球蛋白在2小时胚胚胚层中共定位。在14小时内，它在胚胎横纹肌中积累最强烈，类似于肌球蛋白。dUNC-45定位于3龄幼虫体壁肌肉的肌节z盘。我们制造了一个dunc-45突变体，它的合子表达被破坏了。这导致成熟胚胎中几乎检测不到的dUNC-45水平以及晚期胚胎致死。dunc-45突变体胚胎在14小时时肌球蛋白积累强劲。然而，22小时突变胚胎的体壁肌肉中的肌凝蛋白显著减少。电镜下观察到粗细细丝较少，且粗细细丝晶格间距不规则。通过野生型dunc-45转基因，可以挽救其致死率、缺陷蛋白积累和超微结构异常，表明突变表型是由dunc-45缺乏引起的。总的来说，我们的数据表明dUNC-45对肌球蛋白积累和肌肉功能很重要。此外，我们的研究结果表明，dUNC-45在翻译后作用于适当的肌球蛋白折叠和成熟。
UNC-45 is a chaperone that facilitates folding of myosin motor domains. We have used Drosophila melanogaster to investigate the role of UNC-45 in muscle development and function. Drosophila UNC-45 ( dUNC-45) is expressed at all developmental stages. It colocalizes with non-muscle myosin in embryonic blastoderm of 2-hour-old embryos. At 14 hours, it accumulates most strongly in embryonic striated muscles, similarly to muscle myosin. dUNC-45 localizes to the Z-discs of sarcomeres in third instar larval body-wall muscles. We produced a dunc-45 mutant in which zygotic expression is disrupted. This results in nearly undetectable dUNC-45 levels in maturing embryos as well as late embryonic lethality. Muscle myosin accumulation is robust in dunc-45 mutant embryos at 14 hours. However, myosin is dramatically decreased in the body-wall muscles of 22-hour-old mutant embryos. Furthermore, electron microscopy showed only a few thick filaments and irregular thick-thin filament lattice spacing. The lethality, defective protein accumulation, and ultrastructural abnormalities are rescued with a wild-type dunc-45 transgene, indicating that the mutant phenotypes arise from the dUNC-45 deficiency. Overall, our data indicate that dUNC-45 is important for myosin accumulation and muscle function. Furthermore, our results suggest that dUNC-45 acts post-translationally for proper myosin folding and maturation.