Wang Vincent Y, Hassan Bassem A, Bellen Hugo J, Zoghbi Huda Y
Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA.
Curr Biol. 2002 Sep 17;12(18):1611-6. doi: 10.1016/s0960-9822(02)01144-2.
Many genes share sequence similarity between species, but their properties often change significantly during evolution. For example, the Drosophila genes engrailed and orthodenticle and the onychophoran gene Ultrabithorax only partially substitute for their mouse or Drosophila homologs. We have been analyzing the relationship between atonal (ato) in the fruit fly and its mouse homolog, Math1. In flies, ato acts as a proneural gene that governs the development of chordotonal organs (CHOs), which serve as stretch receptors in the body wall and joints and as auditory organs in the antennae. In the fly CNS, ato is important not for specification but for axonal arborization. Math1, in contrast, is required for the specification of cells in both the CNS and the PNS. Furthermore, Math1 serves a role in the development of secretory lineage cells in the gut, a function that does not parallel any known to be served by ato. We wondered whether ato and Math1 might be more functionally homologous than they appear, so we expressed Math1 in ato mutant flies and ato in Math1 null mice. To our surprise, the two proteins are functionally interchangeable.
许多基因在不同物种间具有序列相似性，但其特性在进化过程中往往会发生显著变化。例如，果蝇的engrailed和orthodenticle基因以及栉蚕的Ultrabithorax基因只能部分替代其小鼠或果蝇的同源基因。我们一直在分析果蝇中的无调性基因（ato）与其小鼠同源基因Math1之间的关系。在果蝇中，ato作为一种原神经基因，控制着弦音器官（CHOs）的发育，弦音器官在体壁和关节中作为拉伸感受器，在触角中作为听觉器官。在果蝇中枢神经系统中，ato对细胞特化并不重要，而是对轴突分支很重要。相比之下，Math1是中枢神经系统和外周神经系统中细胞特化所必需的。此外，Math1在肠道分泌谱系细胞的发育中发挥作用，这一功能与已知的ato所具有的任何功能都不相同。我们想知道ato和Math1在功能上是否比它们看起来更具同源性，于是我们在ato突变果蝇中表达Math1，在Math1基因敲除小鼠中表达ato。令我们惊讶的是，这两种蛋白质在功能上是可互换的。
