Background

Heparan sulfate (HS) is a sulfated linear polysaccharide on cell surfaces that plays an important role in physiological processes. HS is present in skeletal muscles but its detailed role in this tissue remains unclear.

Methods

We examined the role of HS in the differentiation of C2C12 cells, a mouse myoblast cell line. We also phenotyped the impact of HS deletion in mouse skeletal muscles on their functions by using Cre-loxP system.

Results

CRISPR-Cas9-dependent HS deletion or pharmacological removal of HS dramatically impaired myoblast differentiation of C2C12 cells. To confirm the importance of HS in vivo, we deleted Ext1, which encodes an enzyme essential for HS biosynthesis, specifically in the mouse skeletal muscles (referred to as mExt1CKO mice). Treadmill and wire hang tests demonstrated that mExt1CKO mice exhibited muscle weakness. The contraction of isolated soleus muscles from mExt1CKO mice was also impaired. Morphological examination of mExt1CKO muscle tissue under light and electron microscopes revealed smaller cross sectional areas and thinner myofibrils. Finally, a model of muscle regeneration following BaCl₂ injection into the tibialis anterior muscle of mice demonstrated that mExt1CKO mice had reduced expression of myosin heavy chain and an increased number of centronucleated cells. This indicates that muscle regeneration after injury was attenuated in the absence of HS expression in muscle cells.

Significance

These results demonstrate that HS plays an important role in skeletal muscle function by promoting differentiation.

中文翻译：

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硫酸乙酰肝素控制骨骼肌的分化和运动功能。

背景

硫酸乙酰肝素（HS）是细胞表面的硫酸化线性多糖，在生理过程中起重要作用。HS存在于骨骼肌中，但其在该组织中的详细作用仍不清楚。

方法

我们检查了HS在C2C12细胞（一种小鼠​​成肌细胞系）分化中的作用。我们还通过使用Cre-loxP系统对小鼠骨骼肌中HS缺失对其功能的表型进行了表型化。

结果

依赖CRISPR-Cas9的HS缺失或HS的药理学去除作用显着损害C2C12细胞的成肌细胞分化。为了确认HS在体内的重要性，我们删除了Ext1，它编码HS生物合成所必需的一种酶，特别是在小鼠骨骼肌（称为mExt1CKO小鼠）中。跑步机和电线悬挂测试表明，mExt1CKO小鼠表现出肌肉无力。来自mExt1CKO小鼠的离体比目鱼肌的收缩也受到损害。在光镜和电镜下对mExt1CKO肌肉组织进行形态学检查，发现其横截面积更小，肌原纤维更薄。最后，建立了BaCl _2之后的肌肉再生模型小鼠胫骨前肌的注射证明mExt1CKO小鼠的肌球蛋白重链表达降低，而中心核细胞数量增加。这表明在肌肉细胞中不存在HS表达的情况下，损伤后的肌肉再生减弱。

意义

这些结果表明，HS通过促进分化在骨骼肌功能中起重要作用。