Gong Z Y, Brandhorst B P
Biology Department, McGill University, Montreal, Quebec, Canada.
Mol Cell Biol. 1987 Dec;7(12):4238-46. doi: 10.1128/mcb.7.12.4238-4246.1987.
Deciliation by hypertonic shock of embryos of the sea urchin Lytechinus pictus resulted in an increase in synthesis of alpha- and beta-tubulins, the consequence of an increased concentration of RNA encoding the tubulins. RNA run-on assays in isolated nuclei indicated that this response is due to a transient increase in the rate of synthesis of tubulin RNA beginning within 5 min of deciliation. This enhancement of tubulin gene transcription also occurred in deciliated embryos treated with the microtubule-depolymerizing agent colcemid; thus the reaction to deciliation is not a response to a reduction in concentration of unpolymerized tubulin utilized for ciliogenesis. In deciliated embryos treated with colcemid, the elevated level of tubulin RNA declined rapidly, due to its destabilization by the elevated concentration of unpolymerized tubulin. The increased transcription of tubulin genes is a response to the loss of cilia, not to the hypertonic shock, and occurs even when cilium regeneration is prevented. Inhibition of protein synthesis with puromycin or emetine did not prevent the transcriptional enhancement but stabilized tubulin mRNA, resulting in increased accumulation of tubulin mRNA after deciliation.
用高渗休克法使海胆Lytechinus pictus胚胎脱纤毛，导致α-微管蛋白和β-微管蛋白的合成增加，这是编码微管蛋白的RNA浓度增加的结果。对分离细胞核进行的RNA连续分析表明，这种反应是由于脱纤毛后5分钟内微管蛋白RNA合成速率短暂增加所致。微管蛋白基因转录的这种增强也发生在用微管解聚剂秋水仙酰胺处理的脱纤毛胚胎中；因此，对脱纤毛的反应不是对用于纤毛发生的未聚合微管蛋白浓度降低的反应。在用秋水仙酰胺处理的脱纤毛胚胎中，微管蛋白RNA水平升高后迅速下降，这是由于未聚合微管蛋白浓度升高使其不稳定所致。微管蛋白基因转录增加是对纤毛丧失的反应，而不是对高渗休克的反应，即使在阻止纤毛再生时也会发生。用嘌呤霉素或依米丁抑制蛋白质合成并不能阻止转录增强，但能稳定微管蛋白mRNA，导致脱纤毛后微管蛋白mRNA积累增加。
