Artur Jarmołowski & Zofia Szweykowska-Kulińska Lab: R-loops at microRNA encoding loci promote co-transcriptional processing of pri-miRNAs in plants published in Nature Plants, 21st April 2022
Artur Jarmołowski and Zofia Szweykowska-Kulińska groups in collaboration with Paulo Manavella Lab have published their work on the plant miRNA biogenesis in Nature Plants – congratulations! Check out the paper https://www.nature.com/articles/s41477-022-01125-x!
![plant-mirna-biogenesis](https://ibmib.web.amu.edu.pl/wp-content/uploads/2023/07/plant-mirna-biogenesis-1024x486.png)
In most organisms, the maturation of nascent RNAs is coupled to transcription. Unlike in animals, the RNA polymerase II (RNAPII) transcribes microRNA genes (MIRNAs) as long and structurally variable pri-miRNAs in plants. Current evidence suggests that the miRNA biogenesis complex assembly initiates early during the transcription of pri-miRNAs in plants. However, it is unknown whether miRNA processing occurs co-transcriptionally. In the study of Jarmolowski, Szweykowska-Kulika and Manavella Labs they used native elongating transcript sequencing data and imaging techniques to demonstrate that plant miRNA biogenesis occurs coupled to transcription.
![plant-mirna-biogenesis2](https://ibmib.web.amu.edu.pl/wp-content/uploads/2023/07/plant-mirna-biogenesis2.png)
They found that the entire biogenesis occurs co-transcriptionally for pri-miRNAs processed from the loop of the hairpin but requires a second nucleoplasmic step for those processed from the base. Furthermore, they found that co- and post-transcriptional miRNA processing mechanisms co-exist for most miRNAs in a dynamic balance.
![plant-mirna-biogenesis3](https://ibmib.web.amu.edu.pl/wp-content/uploads/2023/07/plant-mirna-biogenesis3.png)
Notably, they discovered that R-loops, formed near the transcription start site region of MIRNAs, promote co-transcriptional pri-miRNA processing. Furthermore, our results suggest the neofunctionalization of co-transcriptionally processed miRNAs, boosting countless regulatory scenarios. The contents of the paper has been previewed by Jiaying Zhu et al. https://www.nature.com/articles/s41477-022-01124-y and highlighted in Twitter thread: https://twitter.com/manavellalab/status/1517190298174169095