RNA poly (a) tail is an essential component of mature mRNA and lncRNA, important for RNA stability and translation regulation.
Researchers form Dr. LU Falong's lab at the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences, recently established a new accurate and sensitive method to analyze RNA poly (A) tails.
This method is able to read the full length RNA isoforms with the entire poly (A) tail sequences using the PacBio sequencing platform. The full isoform information couple with poly (A) tail information allows the study of the relationship between RNA splicing and poly (A) tail regulation. Moreover, it is sensitive enough to analyze single GV oocytes，which makes it particularly suitable for rare samples that cannot be obtained in good quantity.
Interestingly, this method reveals that the poly (A) tail is not only composed of A residues. This study also revealed that more than 17% of the mRNAs harbor non-A (U, G and C) residues within the body of poly (A) tails in mouse GV oocytes, besides those known non-A residues at the 3' ends.
Recently, non-A residues were also found in Arabidopsis, C. elegens and human cell lines. How these newly discovered non-A residues in poly (A) tails are generated, and the biological function of these modifications awaits further investigation.
These findings along with the PAIso-seq method may open the door to a new layer of RNA post-transcriptional regulations.
This work was supported by the Ministry of Science and Technology, the National Natural Science Foundation of China, the Chinese Academy of Sciences and the State Key Laboratory of Molecular Developmental Biology.