Identification and characterization of Fbxl22, a novel skeletal muscle atrophy-promoting E3 ubiquitin ligase
Identification and characterization of Fbxl22, a novel skeletal muscle atrophy-promoting E3 ubiquitin ligase
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DOI：
10.1152/ajpcell.00253.2020
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发表时间：
2020-10-01
影响因子：
5.5
通讯作者：
Bodine, Sue C.
中科院分区：
文献类型：
--
作者：
Hughes, David C.;Baehr, Leslie M.;Bodine, Sue C.
肌肉特异性E3泛素连接酶已在肌肉萎缩诱导条件下被确定。本研究的目的是探讨F-box和富含亮氨酸的蛋白22 （Fbxl22）以及一种新发现的剪接变体（Fbxl22-193）在骨骼肌稳态和神经源性肌肉萎缩中的功能作用。在小鼠C2C12肌细胞中，克隆Fbx122基因的启动子片段，并与分泌的碱性磷酸酶报告基因融合，以评估Fbx122的转录调控。用含两种fbx22剪接变异体cDNA的表达质粒电刺C57/BL6雄性小鼠（12-16周龄）胫骨前肌和7、14岁后收集的组织。28天。用fbx22 RNAi或空质粒电穿孔野生型和肌肉特异性环指1敲除（MuRF1 KO）小鼠腓肠肌，转染后3天去神经，去神经后7天收集组织。全长基因和新的剪接变异在神经源性肌肉萎缩早期（3天后）被转录诱导。小鼠骨骼肌中fbx22亚型的体内过表达导致肌病/萎缩的证据，表明两者都参与了神经源性肌肉萎缩的过程。在MuRF1 KO小鼠的肌肉中敲低Fbxl22可在去神经支配7天后显著增加肌肉保留。靶向两种E3泛素连接酶似乎对保护失神经支配的肌肉质量损失具有很强的加性作用，这些发现对开发治疗肌肉萎缩的治疗策略具有重要意义。
Muscle-specific E3 ubiquitin ligases have been identified in muscle atrophy-inducing conditions. The purpose of the current study was to explore the functional role of F-box and leucine-rich protein 22 (Fbxl22), and a newly identified splice variant (Fbxl22-193), in skeletal muscle homeostasis and neurogenic muscle atrophy. In mouse C2C12 muscle cells, promoter fragments of the Fbx122 gene were cloned and fused with the secreted alkaline phosphatase reporter gene to assess the transcriptional regulation of Fbxl22. The tibialis anterior muscles of male C57/BL6 mice (12-16 wk old) were electroporated with expression plasmids containing the cDNA of two Fbxl22 splice variants and tissues collected after 7, 14. and 28 days. Gastrocnemius muscles of wild-type and muscle-specific RING finger 1 knockout (MuRF1 KO) mice were electroporated with an Fbxl22 RNAi or empty plasmid and denervated 3 days posttransfection, and tissues were collected 7 days postdenervation. The full-length gene and novel splice variant are transcriptionally induced early (after 3 days) during neurogenic muscle atrophy. In vivo overexpression of Fbxl22 isoforms in mouse skeletal muscle leads to evidence of myopathy/atrophy, suggesting that both are involved in the process of neurogenic muscle atrophy. Knockdown of Fbxl22 in the muscles of MuRF1 KO mice resulted in significant additive muscle sparing 7 days after denervation. Targeting two E3 ubiquitin ligases appears to have a strong additive effect on protecting muscle mass loss with denervation, and these findings have important implications in the development of therapeutic strategies to treat muscle atrophy.