概括
在Xenopus胚胎中,体性5SRNA基因显示出对转录的强烈偏好,而不是卵细胞基因,这是由转录因子IIIA (TFIIIA) 度和结合亲和力驱动的.
科学领域:
- 发育生物学 发展生物学
- 分子遗传学 分子遗传学
- 基因规则 基因规则
背景情况:
- 体和卵细胞5S核糖体RNA (rRNA) 基因的差异转录对于Xenopus发育至关重要.
- 转录因子IIIA (TFIIIA) 在调节5SrRNA基因表达方面发挥着关键作用.
- 之前的研究表明,体和卵细胞5SrRNA基因之间的转录有差异,但根本机制尚未完全阐明.
研究的目的:
- 在发育中的Xenopus胚胎中研究体质5SrRNA基因对卵细胞5SrRNA基因的优先转录的分子机制.
- 确定转录因子IIIA (TFIIIA) 度和结合亲和力在这种差异性基因表达中的作用.
主要方法:
- 将克隆的体和卵细胞5SrRNA基因注入到分裂的Xenopus胚胎中.
- 在体内 (胚胎注射) 和体内 (无细胞提取物) 基因转录的检测.
- 在5S rRNA基因的内部控制区域内对TFIIIA结合部位的突变分析.
- 将TFIIIA注入胚胎,以评估其对内源性5S卵细胞rRNA合成的影响.
主要成果:
- 在注射到Xenopus胚胎时,体质5SrRNA基因被转录为25至200倍,优先于卵细胞5SrRNA基因.
- 这种偏好在体内显著增加,相比于无细胞转录试验.
- 影响TFIIIA结合的突变在体内更加明显,表明TFIIIA的关键作用.
- TFIIIA注射增强了内源性卵细胞5SrRNA合成,即使抑制了DNA复制.
结论:
- 在发育中的Xenopus胚胎中TFIIIA的高度是体质5SrRNA基因优先转录的主要驱动因素.
- 对体和卵细胞5SrRNA基因内部控制区域的TFIIIA结合常数的差异有助于观察到的转录偏好.
- 这些发现强调了转录因子可用性和结合动态在早期发育过程中建立差异性基因表达的重要性.
相关概念视频
Regulation of Expression Occurs at Multiple Steps
Gene expression can be regulated at almost every step from gene to protein. Transcription is the step that is most commonly regulated. This involves the binding of proteins to short regulatory sequences on the DNA. This association can either promote or inhibit the transcription of a gene associated with the respective sequence.
Transcription results in the generation of precursor (pre-mRNA) that consists of both exons and introns, which needs further processing before being translated to a...
Transcription results in the generation of precursor (pre-mRNA) that consists of both exons and introns, which needs further processing before being translated to a...
Combinatorial Gene Control
Combinatorial gene control is the synergistic action of several transcriptional factors to regulate the expression of a single gene. The absence of one or more of these factors may lead to a significant difference in the level of gene expression or repression.
The expression of more than 30,000 genes is controlled by approximately 2000-3000 transcription factors. This is possible because a single transcription factor can recognize more than one regulatory sequence. The specificity in gene...
The expression of more than 30,000 genes is controlled by approximately 2000-3000 transcription factors. This is possible because a single transcription factor can recognize more than one regulatory sequence. The specificity in gene...
General Transcription Factors
Tissue-specific transcription factors contribute to diverse cellular functions in mammals. For example, the gene for beta globin, a major component of hemoglobin, is present in all cells of the body. However, it is only expressed in red blood cells because the transcription factors that can bind to the promoter sequences of the beta globin gene are only expressed in these cells. Tissue-specific transcription factors also ensure that mutations in these factors may impair only the function of...
Regulation of Expression Occurs at Multiple Steps
Gene expression can be regulated at almost every step from gene to protein. Transcription is the step that is most commonly regulated. This involves the binding of proteins to short regulatory sequences on the DNA. This association can either promote or inhibit the transcription of a gene associated with the respective sequence.
Transcription results in the generation of precursor (pre-mRNA) that consists of both exons and introns, which needs further processing before being translated to a...
Transcription results in the generation of precursor (pre-mRNA) that consists of both exons and introns, which needs further processing before being translated to a...
Regulation of Expression at Multiple Steps
The gene expression in cells is regulated at different stages: (i) transcription, (ii) RNA processing, (iii) RNA localization, and (iv) translation. Transcriptional regulation is mediated by regulatory proteins such as transcription factors, activators, or repressors—these control gene expression by initiating or inhibiting the transcription of genes. Once a precursor or pre-mRNA is produced, it undergoes post-transcriptional modification, including 5' capping, splicing, and the addition of a...
Transcriptional Regulation: Riboswitches
Riboswitches are RNA elements that regulate gene expression by altering their secondary structures in response to specific effector molecules. These elements, located in the leader regions of certain mRNAs, act as transcriptional regulators by toggling between alternative conformations to control downstream gene expression. Riboswitch-mediated regulation is a precise mechanism for modulating biosynthetic pathways, as exemplified by the riboflavin biosynthesis pathway in Bacillus...


