Developmental control of histone mRNA and dSLBP synthesis during Drosophila embryogenesis and the role of dSLBP in histone mRNA 3′ end processing in vivo
Developmental control of histone mRNA and dSLBP synthesis during Drosophila embryogenesis and the role of dSLBP in histone mRNA 3′ end processing in vivo
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DOI：
10.1128/mcb.22.7.2267-2282.2002
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发表时间：
2002-04-01
影响因子：
5.3
通讯作者：
Marzluff, WF
中科院分区：
文献类型：
--
作者：
Lanzotti, DJ;Kaygun, H;Marzluff, WF
在后生动物中，组蛋白 mRNA 的 3' 末端不是聚腺苷酸化的，而是以细胞周期调节表达所需的茎环结构结束。果蝇组蛋白 H2b、H3 和 H4 基因中的茎环序列与其他后生动物组蛋白 mRNA 的共有序列相同，但黑腹果蝇组蛋白 H2a 和 H1 基因中的茎环序列是新颖的，dSLBP 以相似的亲和力与这些新颖的茎环序列以及典型的茎环结合。来自含有 dSLBP 中可行的亚等位突变的雌性的卵子中储存的所有五种组蛋白 mRNA 的量大大减少，表明母体种系中需要 dSLBP 来产生每种组蛋白 mRNA。合子 dSLBP 功能缺陷的胚胎由于使用位于每个组蛋白基因中茎环 3' 的聚腺苷酸化信号而积累了所有五种组蛋白 mRNA 的多聚 (A)(+) 版本。由于相邻组蛋白基因的 3' 末端靠近，这些聚腺苷酸化信号可以确保转录终止，以防止通读到下一个基因，这可能会破坏转录或产生反义组蛋白 mRNA，从而触发 RNA 干扰。在早期野生型胚胎发生过程中，普遍存在的合子组蛋白基因转录在第 14 周期 S 期的合胞核周期结束时被激活，在随后的 G(2) 期期间沉默，然后在 G(2) 期结束时以充分描述的有丝分裂结构域模式重新激活。野生型胚胎中母体提供的 dSLBP 蛋白很少或根本没有，并且立即需要 dSLBP 的合子表达来处理新产生的组蛋白前体 mRNA。
In metazoans, the 3' end of histone mRNA is not polyadenylated but instead ends with a stem-loop structure that is required for cell cycle-regulated expression. The sequence of the stem-loop in the Drosophila melanogaster histone H2b, H3, and H4 genes is identical to the consensus sequence of other metazoan histone mRNAs, but the sequence of the stem-loop in the D. melanogaster histone H2a and H1 genes is novel, dSLBP binds to these novel stem-loop sequences as well as the canonical stem-loop with similar affinity. Eggs derived from females containing a viable, hypomorphic mutation in dSLBP store greatly reduced amounts of all five histone mRNAs in the egg, indicating that dSLBP is required in the maternal germ line for production of each histone mRNA. Embryos deficient in zygotic dSLBP function accumulate poly(A)(+) versions of all five histone mRNAs as a result of usage of polyadenylation signals located 3' of the stem-loop in each histone gene. Since the 3' ends of adjacent histone genes are close together, these polyadenylation signals may ensure the termination of transcription in order to prevent read-through into the next gene, which could possibly disrupt transcription or produce antisense histone mRNA that might trigger RNA interference. During early wild-type embryogenesis, ubiquitous zygotic histone gene transcription is activated at the end of the syncytial nuclear cycles during S phase of cycle 14, silenced during the subsequent G(2) phase, and then reactivated near the end of that G(2) phase in the well-described mitotic domain pattern. There is little or no dSLBP protein provided maternally in wild-type embryos, and zygotic expression of dSLBP is immediately required to process newly made histone pre-mRNA.