Harlow P, Nemer M
Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111.
Genes Dev. 1987 Dec;1(10):1293-304. doi: 10.1101/gad.1.10.1293.
beta-Tubulin mRNAs associated with cilium formation in Strongylocentrotus purpurpatus sea urchin embryos are expressed selectively from a multiple gene family. The accumulations of three beta-tubulin mRNAs (beta 1, beta 2, and beta 3) are temporally coordinated with ciliogenesis during blastula development and with the regeneration of cilia after their amputation. In contrast, another beta-tubulin mRNA, beta 4, is not induced in either case. The zinc-animalized embryo with its exaggerated blastula phenotype forms longer cilia through a protracted period of ciliogenesis, in which the beta-tubulin mRNAs, principally beta 1, accumulate to higher than normal levels. The rate of beta-tubulin transcription per nucleus in the animalized embryo is greater than that of the normal embryo and is not changed through deciliation, although the tubulin mRNAs accumulate to higher levels. However, deciliation raises the beta-tubulin transcription rate in the normal embryo to that in the animalized embryo. Thus, the induction of beta-tubulin mRNA by cilium amputation is regulated transcriptionally in the normal embryo, but post-transcriptionally in the zinc-animalized embryos. Moreover, the beta-tubulin genes that are expressed in association with cilium formation appear to be induced selectively within the framework of ectodermal cell-type specificity.
与紫海胆胚胎纤毛形成相关的β-微管蛋白mRNA是从一个多基因家族中选择性表达的。三种β-微管蛋白mRNA（β1、β2和β3）的积累在囊胚发育过程中与纤毛发生以及纤毛切断后的再生在时间上是协调的。相比之下，另一种β-微管蛋白mRNA，β4，在这两种情况下都不会被诱导。具有夸张囊胚表型的锌动物化胚胎通过延长的纤毛发生期形成更长的纤毛，在此期间，β-微管蛋白mRNA，主要是β1，积累到高于正常水平。动物化胚胎中每个细胞核的β-微管蛋白转录速率高于正常胚胎，并且通过去纤毛处理不会改变，尽管微管蛋白mRNA积累到更高水平。然而，去纤毛处理会使正常胚胎中的β-微管蛋白转录速率提高到动物化胚胎中的水平。因此，在正常胚胎中，纤毛切断对β-微管蛋白mRNA的诱导是在转录水平上调节的，但在锌动物化胚胎中是在转录后水平上调节的。此外，与纤毛形成相关表达的β-微管蛋白基因似乎在外胚层细胞类型特异性的框架内被选择性诱导。
