Arginine methylation, catalysed by protein arginine methyltransferases (PRMTs), is a general post-translational modification of proteins that occurs widely in eukaryotes. PRMT family members have been widely implicated in both transcriptional and post-transcriptional regulations of messenger RNA (mRNA). However, the link between PRMTs and ribosomal RNA (rRNA) biogenesis has yet to be described.
Ribosome biogenesis is a highly-regulated fundamental biological progress in all living cells. Its dysfunction in human usually lead to various genetic diseases or cancers. Ribosome biogenesis is well deciphered in budding yeast, however, much remains unknown in higher plant.
Researchers from Dr. CAO Xiaofeng’s group in the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, addressed these important questions. They demonstrate that Arabidopsis PRMT3 (AtPRMT3) regulates ribosome biogenesis by affecting precursor rRNA processing. Disruption of AtPRMT3 results in pleiotropic developmental defects, imbalanced polyribosome profiles, and aberrant pre-rRNA processing. They demonstrate for the first time, that the co-existence of two pre-rRNA processing pathways is conserved in plants. And Arabidopsis PRMT3 is required for the balance between these pathways.
These findings uncover a prevously unidentified function of PRMT in post-transcriptional regulation of rRNA, extending the regulatory scope of PRMTs and revealing an extra layer of complexity in the regulation of ribosome biogenesis. The alternative pre-rRNA processing pathways in plants modulated by PRMT3 may be conserved in other multicellular organisms, thereby shedding light on PRMT functions and regulation of ribosome biogenesis in animals.
This work was published in PNAS online Early Edition on October 28, 2014 (http://www.pnas.org/content/early/2014/10/28/1412697111). The graduate student HANG Runlai is the first author of this work. This work was supported by the National Natural Science Foundation of China, National Basic Research Program of China, the State Key Laboratory of Plant Genomics, and the Chinese Academy of Sciences.
