Maternal inherited siRNA initiate piRNA cluster formation

In order to control transposable element (TE) activity, PIWI-interacting RNAs (piRNAs) have been evolved to silence TE transcriptionally and post-transcriptionally, and produced from heterochromatic genomic loci, called piRNA cluster. Maternal inherited piRNAs transmission is considered as the key step of piRNA cluster maintenance and induction of de nove piRNA cluster formation, however, how the original piRNAs were produced without maternal piRNAs deposition remains unclear. In this paper, we created a repetitive GFP reporter and found a Rhino-dependent piRNA cluster conversion spontaneously occurs to the reporter over generations. Importantly, this conversion is reversible by removal of maternal piRNAs of GFP reporter. Taking advantage of this reversible GFP reporter piRNA cluster, we found that siRNA is able to initiate piRNA cluster formation epigenetically, even when only maternal siRNA presence is capable to do so. Our results suggest the importance of siRNA on initiation of piRNA biogenesis and describe a whole picture of initiation and maintenance of piRNA cluster. Overall design: Genome occupancy profiling and piRNA production by high throughput sequencing The submitter noted that [1] the following processed data files are identical as they contain very few values: dsGPP_66A6_oxidized_piRNA_1st_S19_R1_001_dsGPP_66A6_oxidized_piRNA_1st_S19_R1_001.dm6.21_22mer.unique.dup.bam.10.mir304_12.Minus.bg4.chopped.bg4 dsGPP_66A6_oxidized_piRNA_2nd_S19_R1_001_dsGPP_66A6_oxidized_piRNA_2nd_S19_R1_001.dm6.21_22mer.unique.dup.bam.10.mir304_12.Minus.bg4.chopped.bg4 dsGPP_66A6_oxidized_piRNA_1st_S19_R1_001_dsGPP_66A6_oxidized_piRNA_1st_S19_R1_001.dm6.21_22mer.unique.dup.bam.10.mir304_12.Plus.bg4.chopped.bg4 dsGPP_66A6_oxidized_piRNA_2nd_S19_R1_001_dsGPP_66A6_oxidized_piRNA_2nd_S19_R1_001.dm6.21_22mer.unique.dup.bam.10.mir304_12.Plus.bg4.chopped.bg4 [2] some samples do not have processed data as only BAM/FASTA files were generated.