真核蛋白质编码基因的转录产生未成熟的mRNAs,这些mRNAs会经历一系列加工事件,包括封顶,拼接,乳沟,和聚腺苷酸化(CPA),和碱基的化学修饰。选择性聚腺苷酸化(APA)极大地促进了细胞中的mRNA多样性。通过确定3'个未翻译区域的长度,APA产生具有不同调控元件的转录本,如miRNA和RBP结合位点,会影响mRNA的稳定性,营业额,和翻译。在模型植物拟南芥中,APA参与种子休眠和开花的控制。鉴于APA在植物中的生理重要性,我们决定研究光/暗条件的影响,并将潜在机制与阐明的可变剪接(AS)机制进行比较.我们发现光控制大约30%的拟南芥基因中的APA。类似于AS,光对APA的影响需要功能性叶绿体,在植物色素和隐色素光感受器途径的突变体中不受影响,只有当与光合组织的交流不中断时,才能在根中观察到。此外,线粒体和TOR激酶活性是光作用所必需的。然而,与AS不同,似乎不涉及与转录延伸的偶联,因为TFIIS转录物延伸因子的突变体中既没有消除光依赖性APA调节,也没有受到组蛋白去乙酰化酶抑制引起的染色质松弛的普遍影响。相反,监管似乎与构成注册会计师因素的丰度变化相关,也由叶绿体介导。
Transcription of eukaryotic protein-coding genes generates immature mRNAs that are subjected to a series of processing events, including capping, splicing, cleavage, and polyadenylation (CPA), and chemical modifications of bases. Alternative polyadenylation (APA) greatly contributes to mRNA diversity in the cell. By determining the length of the 3\' untranslated region, APA generates transcripts with different regulatory elements, such as miRNA and RBP binding sites, which can influence mRNA stability, turnover, and translation. In the model plant Arabidopsis thaliana, APA is involved in the control of seed dormancy and flowering. In view of the physiological importance of APA in plants, we decided to investigate the effects of
light/dark conditions and compare the underlying mechanisms to those elucidated for alternative splicing (AS). We found that
light controls APA in approximately 30% of Arabidopsis genes. Similar to AS, the effect of
light on APA requires functional chloroplasts, is not affected in mutants of the phytochrome and cryptochrome photoreceptor pathways, and is observed in roots only when the communication with the photosynthetic tissues is not interrupted. Furthermore, mitochondrial and TOR kinase activities are necessary for the effect of
light. However, unlike AS, coupling with transcriptional elongation does not seem to be involved since
light-dependent APA regulation is neither abolished in mutants of the TFIIS transcript elongation factor nor universally affected by chromatin relaxation caused by histone deacetylase inhibition. Instead, regulation seems to correlate with changes in the abundance of constitutive CPA factors, also mediated by the chloroplast.