NAP-seq:unveiling the hidden world of noncapped RNAs

The human genome sequencing reveals that non-coding sequences can account for about 98%of the genome(Lander et al.,2001;Venter et al.,2001).Comparative genomics studies indicate that the proportion of the non-coding sequence in a species is tightly correlated with the complexity of the species during evolution(Taft et al.,2007),highlighting the functionality of those non-coding sequences.Many transcriptome sequencing studies later revealed that about 80%of the human genome is transcribed,such pervasive transcription generating vast amounts of non-coding RNAs that function directly in gene regulation and disease development(Nemeth et al.,2024;Statello et al.,2021).In contrast to messenger RNAs(mRNAs)that must be capped at the 5′end and polyA tailed at the 3′end,several types of non-coding RNAs have been demonstrated to be noncapped,such as microRNAs and PIWI-interacting RNAs(Bartel,2018;Ozata et al.,2019).Besides those known noncapped RNAs,it remains unclear whether the human genome encodes other types of noncapped RNA and how they function.