Auxin-regulated gene expression.
Auxin-regulated gene expression.
复制标题
生长素调节的基因表达。
DOI：
10.1098/rstb.1986.0063
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
Nagao,RT
中科院分区：
文献类型：
--
作者：
Key,JL;Kroner,P;Walker,J;Hong,JC;Ulrich,TH;Ainley,WM;Gantt,JS;Nagao,RT
在20世纪60年代，广泛的研究提供了一个信息基础，导致提出生长素调节的细胞过程--特别是细胞伸长--可能是由生长素调节的基因表达介导的。我们的工作提供了间接证据，基于RNA合成抑制剂(如放线菌素D)和蛋白质合成抑制剂(如放线菌素)对生长素诱导的细胞伸长的影响，以及生长素对RNA合成和细胞伸长的影响的相关性，为这一建议提供了基础。随着DNA-DNA和DNA-RNA杂交、mRNA分离-翻译、翻译产物的体外2D凝胶分析，以及最终通过重组DNA技术克隆基因组DNA和复制DNA(CDNAs)以形成聚(A)+mRNAs，我们和其他人已经为生长素对几个基因(即聚(A)+RNA水平)表达的影响提供了直接证据。我们的实验室已经提供了生长素下调和上调少数Poly(A)+mRNAs水平的证据，这些序列大约有4×104个序列，不受生长素的显著影响。在我们对生长素调节细胞伸长的研究中，分离到了两个cDNA克隆(pJCW1和pJCW2)，它们对应于Poly(A)+mRNAs，它们在生长转换过程中的反应方式与它们的蛋白产物在细胞伸长中的潜在作用一致。这些mRNAs在大豆下胚轴的伸长带中含量最高。当切除并在没有生长素的情况下孵育时，这些mRNAs随着细胞伸长率的下降而耗尽。在培养液中添加生长素会导致这些mRNAs水平的增加和细胞伸长率的提高。如果在切除培养开始时向培养液中添加生长素，这些mRNAs不会耗尽，细胞延长率仍然很高。我们已经分离并测序了与这些cDNA同源的基因组克隆。在被测序的两个基因中，这两个基因都是小的多基因家族的成员。有一些氨基酸同源性很高的区域，即使这些区域的核苷酸序列有足够的差异，不会观察到克隆的交叉杂交。最近，其他人，特别是吉尔福伊尔的实验室，已经表明生长素选择性地和迅速地影响某些mRNAs和蛋白质的水平。我们已经研究了其他基因系统，如核糖体蛋白和可能的对生长素有反应的细胞壁蛋白；同样，这些基因表达调控的性质尚不清楚。现在的问题不是生长素是否选择性地改变基因表达，从而改变反应组织的生物学，而是生长素改变特定基因表达的机制是什么。此外，这些基因产物的功能仍然是一个“谜”。幸运的是，已经有实验方法可以回答这些问题，并正在积极探索。
During the 1960s a wide range of studies provided an information base that led to the suggestion that auxin-regulated cell processes - especially cell elongation - may be mediated by auxin-regulated gene expression. Indirect evidence from our work, based on the influence of inhibitors of RNA synthesis (e.g. actinomycin D) and of protein synthesis (e.g. cycloheximide) on auxin-induced cell elongation, coupled with correlations of the influence of auxin on RNA synthesis and cell elongation, provided the basis for this suggestion. With the availability of techniques for DNA-DNA and DNA-RNA hybridization, mRNA isolation-translation,in vitro2D gel analysis of the translation products, and ultimately the cloning by recombinant DNA technologies of genomic DNA and copy DNAs (cDNAs) made to poly(A)+mRNAs, we and others have provided direct evidence for the influence of auxin on the expression of a few genes (i.e. poly(A)+RNA levels). Our laboratory has provided evidence for auxin’s both down-regulating and up-regulating the level of a few poly (A)+mRNAs out of a population of about 4 x 104sequences that are not significantly affected by auxin. In our studies on auxin-regulated cell elongation, two cDNA clones (pJCW1 and pJCW2) were isolated which corresponded to poly (A)+mRNAs that responded during growth transitions in a way consistent with a potential role of their protein products in cell elongation. These mRNAs are most abundant in the elongating zone of the soybean hypocotyl. Upon excision and incubation in the absence of auxin, these mRNAs deplete in concert with a decreasing rate of cell elongation. Addition of auxin to the medium results in both increased levels of these mRNAs and enhanced rates of cell elongation. These mRNAs do not deplete if auxin is added to the medium at the onset of excised incubation, and cell elongation rates remain high. We have isolated and sequenced genomic clones that are homologous to these cDNAs. Of the two genes sequenced, both genes are members of small multigene families. There are regions of high amino acid homology even though the nucleotide sequences are sufficiently different in these regions for cross-hybridization of the clones not to be observed. More recently others, especially Guilfoyle’s laboratory, have shown that auxin selectively and rapidly influences the level of certain mRNAs and proteins. We have worked on other gene systems such as ribosomal proteins and possible cell wall proteins that are responsive to auxin; again the nature of regulation of expression of these genes is not known. The question now is not whether auxin selectively alters gene expression and thus the biology of responsive tissues, but what the mechanism is by which auxin alters expression of specific genes. Additionally, the function of these gene products remains a ‘mystery’. Fortunately, experimental approaches are available to answer these questions and are actively being pursued.