Galle Sabina, Yanze Nathalie, Seipel Katja
Institute of Zoology, Biocenter / Pharmacenter, Basel, Switzerland.
Int J Dev Biol. 2005;49(8):961-7. doi: 10.1387/ijdb.052009sg.
Bilaterian Msx homeobox genes are generally expressed in areas of cell proliferation and in association with multipotent progenitor cells. Likewise, jellyfish Msx is expressed in progenitor cells of the developing entocodon, a cell layer giving rise to the striated and smooth muscles of the medusa. However, in contrast to the bilaterian homologs, Msx gene expression is maintained at high levels in the differentiated striated muscle of the medusa in vivo and in vitro. This tissue exhibits reprogramming competence. Upon induction, the Msx gene is immediately switched off in the isolated striated muscle undergoing transdifferentiation, to be upregulated again in the emerging smooth muscle cells which, in a stem cell like manner, undergo quantal cell divisions producing two cell types, a proliferating smooth muscle cell and a differentiating nerve cell. This study indicates that the Msx protein may be a key component of the reprogramming machinery responsible for the extraordinary transdifferentation and regeneration potential of striated muscle in the hydrozoan jellyfish.
两侧对称动物的Msx同源异型盒基因通常在细胞增殖区域表达，并与多能祖细胞相关。同样，水母的Msx基因在发育中的内胚层的祖细胞中表达，内胚层是一个产生水母横纹肌和平滑肌的细胞层。然而，与两侧对称动物的同源物不同，Msx基因在体内和体外的水母分化横纹肌中均维持高水平表达。该组织具有重编程能力。诱导后，Msx基因在经历转分化的分离横纹肌中立即关闭，在新出现的平滑肌细胞中再次上调，这些平滑肌细胞以干细胞样方式进行定量细胞分裂，产生两种细胞类型，即增殖的平滑肌细胞和分化的神经细胞。这项研究表明，Msx蛋白可能是重编程机制的关键组成部分，负责水螅水母横纹肌的非凡转分化和再生潜力。
