Dubois C, Figarella-Branger D, Pastoret C, Rampini C, Karpati G, Rougon G
Laboratoire de Biologie Cellulaire, Faculté de Médecine Saint-Antoine, Paris, France.
Neuromuscul Disord. 1994 May;4(3):171-82. doi: 10.1016/0960-8966(94)90018-3.
In order to understand the mechanism of the muscular regenerative process which occurs in mdx mice, the expression of neural cell adhesion molecule (NCAM) isoforms and their polysialylated (PSA) derivatives were studied during the postnatal development of normal and mdx mice in relation to the stage of the regeneration of muscle fibres, in the quadriceps. NCAM expression was also examined during in vitro differentiation of satellite cells isolated from both mdx and normal muscles. The immunohistochemical and biochemical analyses were done using antibodies for the different isoforms. The data presented here suggest that before the onset of necrosis and regeneration, the expression of NCAM isoforms in the quadriceps of mdx mice was similar to normal mice. Later, NCAM and PSA-NCAM expression in mdx mice increased and was related to the muscular regenerative process, and the overall level of NCAM expression can be considered as a good index of muscle regeneration. Young regenerative fibres expressed NCAM and PSA-NCAM, while mature regenerative fibres, in which myonuclei remained centrally located, did not express either NCAM or the PSA isoforms. Therefore, in terms of NCAM expression, the fibres in mdx muscle with centrally located nuclei appeared similar to mature fibres found in normal adult muscle. A major form of 145 kDa and a minor form of 115 kDa were detected in mdx regenerative muscle. The 145 kDa NCAM was sialylated, as demonstrated by its sensibility to exoneuraminidase which generates a desialoform of 125 kDa, but not polysialylated since it was not recognized by the anti-MenB antibody, specific for PSA-NCAM. In contrast, the molecular forms of NCAM migrating as a broad band from 160 kDa to 220 kDa were identified as PSA-NCAM. The comparison of in vitro differentiation of normal and mdx satellite cells showed that the expression of NCAM isoforms by mdx cells was similar to that expressed by normal cells. Both our in vivo and in vitro data concerning NCAM expression show that regeneration in mdx mice does not differ from that observed in other necrotic diseases. In other words, NCAM is unlikely to be a dystrophin-associated molecule since lack of dystrophin does not affect its expression.
为了了解mdx小鼠肌肉再生过程的机制，研究了正常小鼠和mdx小鼠出生后发育过程中神经细胞黏附分子（NCAM）异构体及其多唾液酸化（PSA）衍生物的表达情况，这些表达与股四头肌中肌纤维再生阶段相关。还检测了从mdx肌肉和正常肌肉分离出的卫星细胞在体外分化过程中的NCAM表达。使用针对不同异构体的抗体进行免疫组织化学和生化分析。此处呈现的数据表明，在坏死和再生开始之前，mdx小鼠股四头肌中NCAM异构体的表达与正常小鼠相似。之后，mdx小鼠中NCAM和PSA-NCAM的表达增加，且与肌肉再生过程相关，NCAM表达的总体水平可被视为肌肉再生的良好指标。年轻的再生纤维表达NCAM和PSA-NCAM，而成熟的再生纤维（其肌核仍位于中央）既不表达NCAM也不表达PSA异构体。因此，就NCAM表达而言，mdx肌肉中核位于中央的纤维看起来与正常成年肌肉中的成熟纤维相似。在mdx再生肌肉中检测到一种主要的145 kDa形式和一种次要的11 kDa形式。1 kDa的NCAM被唾液酸化，这可通过其对外切神经氨酸酶敏感得到证明，外切神经氨酸酶会产生125 kDa的去唾液酸化形式，但它没有被多唾液酸化，因为它不被针对PSA-NCAM的抗MenB抗体识别。相比之下，迁移为160 kDa至220 kDa宽带的NCAM分子形式被鉴定为PSA-NCAM。正常卫星细胞和mdx卫星细胞体外分化的比较表明，mdx细胞中NCAM异构体的表达与正常细胞相似。我们关于NCAM表达的体内和体外数据均表明，mdx小鼠的再生与其他坏死性疾病中观察到的再生没有差异。换句话说，NCAM不太可能是一种与肌营养不良蛋白相关的分子，因为缺乏肌营养不良蛋白并不影响其表达。
