Palusa Saiprasad Goud, Reddy Anireddy S N
Department of Biology, Program in Molecular Plant Biology, Program in Cell and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA.
Department of Biology, Program in Molecular Plant Biology, Program in Cell and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
Plant Cell Physiol. 2015 Mar;56(3):421-7. doi: 10.1093/pcp/pcv010. Epub 2015 Jan 29.
We have previously shown that precursor mRNAs (pre-mRNAs) of serine/arginine-rich (SR) proteins are extensively alternatively spliced to generate approximately 100 distinct splice variants from 14 SR genes and that the splicing pattern of SR pre-mRNAs changes in different organs and in response to abiotic stresses. About half of the splice variants are potential targets of nonsense-mediated decay (NMD) and 25 splice forms were confirmed to be real NMD targets. However, it is not known whether (i) all splice variants are recruited to polysomes for translation; (ii) there is a preferential recruitment of specific splice isoforms to polysomes; and (iii) there is a differential recruitment of splice variants during development and in response to stresses. To address these questions, we analyzed the association of SR splice variants with polysomes from seedlings, different organs and seedlings exposed to heat and cold stress. In seedlings, about one-third of the splice variants (22 out of 72) are not recruited to polysomes. Among those associated with polysomes, the functional isoforms that code for full-length proteins and some candidate putative and confirmed NMD targets were identified. There was preferential recruitment of some splice forms over others. Predominant recruitment of functional isoforms along with a few NMD candidates was found in different organs. Furthermore, we observed differential recruitment of isoforms in different organs. Heat and cold stress enhanced or reduced recruitment of specific splice variants. Our studies reveal differential recruitment of SR splice variants to polysomes under normal conditions, during development and in response to stresses.
我们之前已经表明，富含丝氨酸/精氨酸（SR）蛋白的前体mRNA（pre-mRNA）会广泛地发生可变剪接，从14个SR基因产生约100种不同的剪接变体，并且SR pre-mRNA的剪接模式在不同器官以及对非生物胁迫的响应中会发生变化。大约一半的剪接变体是无义介导的mRNA降解（NMD）的潜在靶标，并且已证实25种剪接形式是真正的NMD靶标。然而，尚不清楚：（i）所有剪接变体是否都被募集到多核糖体上进行翻译；（ii）是否存在特定剪接异构体向多核糖体的优先募集；以及（iii）在发育过程中和对胁迫的响应中，剪接变体的募集是否存在差异。为了解决这些问题，我们分析了SR剪接变体与来自幼苗、不同器官以及暴露于热胁迫和冷胁迫下的幼苗的多核糖体之间的关联。在幼苗中，约三分之一的剪接变体（72种中的22种）未被募集到多核糖体上。在那些与多核糖体相关的变体中，鉴定出了编码全长蛋白的功能异构体以及一些候选的推定和已证实的NMD靶标。某些剪接形式比其他形式有优先募集。在不同器官中发现了功能异构体以及一些NMD候选物的主要募集。此外，我们观察到不同器官中异构体的募集存在差异。热胁迫和冷胁迫增强或减少了特定剪接变体的募集。我们的研究揭示了在正常条件下、发育过程中和对胁迫的响应中，SR剪接变体向多核糖体的差异募集。
