Lo D C, Allen F, Brockes J P
Ludwig Institute for Cancer Research, University College London, United Kingdom.
Proc Natl Acad Sci U S A. 1993 Aug 1;90(15):7230-4. doi: 10.1073/pnas.90.15.7230.
Recent studies suggest that maintenance of the differentiated state requires continuous regulation. Limb regeneration in urodele amphibians provides a context in which to address this issue, as limb regeneration may involve the dedifferentiation of multinucleate myotubes to yield mononucleate blastemal cells, which then proliferate and contribute to regenerate tissues. To evaluate this possibility, cultured newt limb myotubes were selectively microinjected with the lineage tracer rhodamine-dextran and introduced into regenerating limbs. In culture, such labeled myotubes were stable after 6-8 weeks, and transfer of the tracer to mononucleate cells was not observed. In contrast, after implantation of labeled myotubes under the wound epidermis of limb blastemas, strongly labeled mononucleate cells were observed after 1 week. These cells could be double-labeled with the cytoplasmic lineage tracer and [3H]thymidine that had been incorporated into the nuclei of implanted myotubes. The number of labeled mononucleate cells increased significantly by 2-3 weeks after implantation, indicating that these cells proliferated. Although the fate of these cells at later times was uncertain, we provide evidence consistent with their subsequent differentiation. These results demonstrate reversal in the mononucleate-to-multinucleate transition of vertebrate myogenesis.
最近的研究表明，维持分化状态需要持续调控。有尾两栖动物的肢体再生为解决这一问题提供了一个背景，因为肢体再生可能涉及多核肌管去分化产生单核芽基细胞，这些细胞随后增殖并参与再生组织的形成。为了评估这种可能性，将谱系示踪剂罗丹明 - 葡聚糖选择性地显微注射到培养的蝾螈肢体肌管中，然后将其植入正在再生的肢体中。在培养过程中，这种标记的肌管在6 - 8周后是稳定的，并且未观察到示踪剂转移到单核细胞中。相反，将标记的肌管植入肢体芽基的伤口表皮下后，1周后观察到强烈标记的单核细胞。这些细胞可以用细胞质谱系示踪剂和已掺入植入肌管细胞核中的[3H]胸腺嘧啶核苷进行双重标记。植入后2 - 3周，标记的单核细胞数量显著增加，表明这些细胞进行了增殖。尽管这些细胞在后期的命运尚不确定，但我们提供了与它们随后分化一致的证据。这些结果证明了脊椎动物肌生成中单核到多核转变的逆转。
