pNET-seq (Pol II Ser5) in Arabidopsis

Intronic transposon elements (TEs) comprise a large proportion in eukaryotic genomes, but how they regulate the host genes remains to be explored. Our forward genetic screen disclosed the plant specific RNA polymerases IV and V in suppressing intronic TE-mediated cryptic transcription initiation of a chimeric transcripts at FLC (FLCTE). Initiation of FLCTE transcription is blocked by the locally formed intronic heterochromatin, and RNA Pol V direct associates and establishes intronic heterochromatin, thus inhibits the entry of RNA Pol II Ser5p and the occupancy of H3K4 methylation for promoting initiation. Genome-wide Pol II Ser5p native elongation transcription sequencing revealed that this is a common mechanism among intronic heterochromatin-containing genes. This study sheds light on deeply understanding the function of intronic heterochromatin on host genes expression in eukaryotic genome. We conducted pNET-seq with Arabidopsis wild-type (Col-0) and nrpe1-11 mutant seedlings to proflie the Pol II (Ser5) associated RNA.