METHODS: To identify whether increased lipin1 expression could prevent dystrophic pathology, we employed unique muscle-specific mdx:lipin1 transgenic (mdx:lipin1Tg/0) mice in which lipin1 was restored in the dystrophic muscle of mdx mice, intramuscular gene delivery, as well as cell culture system.
RESULTS: We found that increased lipin1 expression suppressed muscle degeneration and inflammation, reduced fibrosis, strengthened membrane integrity, and resulted in improved muscle contractile and lengthening force, and muscle performance in mdx:lipin1Tg/0 compared to mdx mice. To confirm the role of lipin1 in dystrophic muscle, we then administered AAV1-lipin1 via intramuscular injection in mdx mice. Consistently, lipin1 restoration inhibited myofiber necroptosis and lessened muscle degeneration. Using a cell culture system, we further found that differentiated primary mdx myoblasts had elevated expression levels of necroptotic markers and medium creatine kinase (CK), which could be a result of sarcolemmal damage. Most importantly, increased lipin1 expression levels in differentiated myoblasts from mdx:lipin1Tg/0 mice substantially inhibited the elevation of necroptotic markers and medium CK levels.
CONCLUSIONS: Overall, our data suggest that lipin1 is a promising therapeutic target for the treatment of dystrophic muscles.
方法:为了确定增加的lipin1表达是否可以预防营养不良病理,我们采用了独特的肌肉特异性mdx:lipin1转基因(mdx:lipin1Tg/0)小鼠,其中lipin1在mdx小鼠的营养不良肌肉中恢复,肌内基因递送,以及细胞培养系统。
结果:我们发现增加的lipin1表达抑制了肌肉变性和炎症,减少纤维化,加强膜的完整性,并改善了肌肉收缩力和伸长力,与mdx小鼠相比,mdx:lipin1Tg/0的肌肉表现。为了证实lipin1在营养不良肌肉中的作用,然后,我们通过肌肉注射给mdx小鼠施用AAV1-lipin1。始终如一,lipin1修复抑制肌纤维坏死并减轻肌肉变性。使用细胞培养系统,我们进一步发现分化的原代mdx成肌细胞的坏死标志物和中等肌酸激酶(CK)的表达水平升高,这可能是肌膜损伤的结果.最重要的是,mdx:lipin1Tg/0小鼠分化成肌细胞中lipin1表达水平的增加基本上抑制了坏死标志物和中等CK水平的升高。
结论:总体而言,我们的数据表明,lipin1是治疗营养不良性肌肉的一个有前景的治疗靶点.