MyoD-/- satellite cells in single-fiber culture are differentiation defective and MRF4 deficient
MyoD-/- satellite cells in single-fiber culture are differentiation defective and MRF4 deficient
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DOI：
10.1006/dbio.2000.9682
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发表时间：
2000-08-15
影响因子：
2.7
通讯作者：
Wold, BJ
中科院分区：
文献类型：
--
作者：
Cornelison, DDW;Olwin, BB;Wold, BJ
肌缺陷小鼠在胚胎发生和胎儿发育过程中没有明显的有害肌肉表型，实验室成年小鼠的骨骼肌和寿命基本正常。然而，先前的一项研究表明，在mdx（肌营养不良蛋白缺失）遗传背景下的肌肉变性背景下，缺乏MyoD的动物具有大大增强的疾病表型，导致致死率，而在mds小鼠中则没有这种情况。在这里，我们在单个肌纤维培养中检查了MyoD（-/-）成人肌纤维及其相关的卫星细胞，并描述了在组织、细胞和分子水平上发现的主要表型差异。新分离的MyoD（-/-）纤维上的卫星细胞稳态数量增加，并观察到异常的分支纤维形态，后者提示体内慢性肌肉再生。单细胞RNA共表达分析c-met、m-cadherin和四种肌生成调节因子（MRFs）。大多数突变卫星细胞进入细胞周期并上调myf5的表达，这两者都是卫星细胞成熟的早期特征。然而，他们后来不能正常上调MRF4，表现出m-cadherin表达的严重缺陷，并且与野生型相比，myogenin阳性状态显着降低。MyoD（-/-）卫星细胞形成不寻常的聚集结构，无法有效融合，分化效率比野生型降低90%以上。对编码生长和分化、细胞周期进程和细胞信号传导调节因子的rna的进一步调查显示，大多数基因的表达谱相似或相同，但也存在一些值得注意的差异。其中，GDF8和Msx1被确定为静止状态的潜在重要调控因子，其表达谱在突变型和野生型之间存在差异。综合考虑，这些数据表明，与野生型相比，活化的MyoD（-/-）卫星细胞的表型在某些方面类似于发育“停滞”的细胞。然而，MyoD（-/-）细胞不仅仅是发育不成熟的，因为它们还表现出不同于任何阶段野生型肌肉前体的新分子和细胞特征。(C) 2000年学术出版社。
MyoD-deficient mice are without obvious deleterious muscle phenotype during embryogenesis and fetal development, and adults in the laboratory hare grossly normal skeletal muscle and Life span. However, a previous study showed that in the context of muscle degeneration on a mdx (dystrophin null) genetic background, animals lacking MyoD have a greatly intensified disease phenotype leading to lethality not otherwise seen in mds mice. Here we have examined MyoD(-/-) adult muscle fibers and their associated satellite cells in single myofiber cultures and describe major phenotypic differences found at the tissue, cellular, and molecular levels. The steady-state number of satellite cells on freshly isolated MyoD(-/-) fibers was elevated and abnormal branched fiber morphologies were observed, the latter suggesting chronic muscle regeneration in vivo. Single-cell RNA coexpression analyses were performed for c-met, m-cadherin, and the four myogenic regulatory factors (MRFs.) Most mutant satellite cells entered the cell cycle and upregulated expression of myf5, both characteristic early steps in satellite cell maturation. However, they later failed to normally upregulate MRF4, displayed a major deficit in m-cadherin expression, and showed a significant diminution in myogenin-positive status compared with wildtype. MyoD(-/-) satellite cells formed unusual aggregate structures, failed to fuse efficiently, and showed greater than 90% reduction in differentiation efficiency relative to wildtype. A further survey of RNAs encoding regulators of growth and differentiation, cell cycle progression, and cell signaling revealed similar or identical expression profiles for most genes as well as several noteworthy differences. Among these, GDF8 and Msx1 were identified as potentially important regulators of the quiescent state whose expression profile differs between mutant and wildtype. Considered together, these data suggest that activated MyoD(-/-) satellite cells assume a phenotype that resembles in some ways a developmentally "stalled" cell compared to wildtype. However, the MyoD(-/-) cells are not merely developmentally immature, as they also display novel molecular and cellular characteristics that differ from any observed in wild-type muscle precursor counterparts of any stage. (C) 2000 Academic Press.