Nucleotide- and Protein-Dependent Functions of Actg1.
Nucleotide- and Protein-Dependent Functions of Actg1.
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DOI：
10.1091/mbc.e22-02-0054
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发表时间：
2022-08-01
影响因子：
3.3
通讯作者：
Ervasti, James M.
中科院分区：
文献类型：
--
作者：
Sundby, Lauren J.;Southern, William M.;Hawbaker, Katelin M.;Trujillo, Jesus M.;Perrin, Benjamin J.;Ervasti, James M.
细胞质β-和γ-肌动蛋白99%相同，但支持独特的生物功能。细胞质肌动蛋白核苷酸序列Actb和Actg 1分别更加不同，但仍有89%的相似性。Actb-/-小鼠是胚胎致死的，Actb-/-细胞不能增殖，但编辑Actb基因以表达γ-肌动蛋白（Actbc-g）导致敲除的显性表型均未揭示Actb的蛋白质独立功能。为了确定Actg 1是否具有蛋白质非依赖性功能，我们将Actbc-g和Actg 1-/-小鼠杂交以产生bG/0系，其中唯一表达的细胞质肌动蛋白是来自Actbc-g的γ-肌动蛋白。bG/0小鼠存活，但显示出存活缺陷，尽管表达的γ-肌动蛋白水平与正常存活的bG/gG没有差异。在bG/0小鼠中也观察到独特的肌病表型。我们得出结论，bG/0小鼠的存活率受损和肌病是由于Actg 1核苷酸依赖性功能的丧失。另一方面，bG/0基因型挽救了Actg 1-/-受损的功能，包括细胞增殖和听觉功能，表明γ-肌动蛋白在成纤维细胞和听力中的作用。总之，这些结果确定了Actg 1的核苷酸依赖性功能，同时暗示γ-肌动蛋白蛋白具有更多的细胞/组织特异性功能。
Cytoplasmic β- and γ-actin proteins are 99% identical but support unique organismal functions. The cytoplasmic actin nucleotide sequences Actb and Actg1, respectively, are more divergent but still 89% similar. Actb–/– mice are embryonic lethal and Actb–/– cells fail to proliferate, but editing the Actb gene to express γ-actin (Actbc–g) resulted in none of the overt phenotypes of the knockout revealing protein-independent functions for Actb. To determine if Actg1 has a protein-independent function, we crossed Actbc–g and Actg1–/– mice to generate the bG/0 line, where the only cytoplasmic actin expressed is γ-actin from Actbc–g. The bG/0 mice were viable but showed a survival defect despite expressing γ-actin protein at levels no different from bG/gG with normal survival. A unique myopathy phenotype was also observed in bG/0 mice. We conclude that impaired survival and myopathy in bG/0 mice are due to loss of Actg1 nucleotide-dependent function(s). On the other hand, the bG/0 genotype rescued functions impaired by Actg1–/–, including cell proliferation and auditory function, suggesting a role for γ-actin protein in both fibroblasts and hearing. Together, these results identify nucleotide-dependent functions for Actg1 while implicating γ-actin protein in more cell-/tissue-specific functions.