Project description:To explore the roles of piRNAs in regulating 22G-RNA production and transgenerational gene silencing, we used RNA-seq to assess changes in small RNA and mRNA levels in piwi/prg-1 and mutator mutants at an early generation and again at a late generation. We identified that in the absence of piRNAs, many genes gain 22G-RNAs which in turn guide transgenerational gene silencing.
Project description:C.elegans small RNAs from HA::ALG-1, HA::ALG-2 and HA::RDE-1 IP and rde-1 mutants Small RNAs were cloned from transgenic or mutant C. elegans adults. Sequencing was performed using 454 and Illumina platforms.
Project description:To explore the roles of piRNAs and WAGO-class 22G-RNAs in regulating gene expression and transposon silencing in Caenorhabditis elegans, we used RNA-seq to assess changes in small RNA and mRNA levels in prg-1 and mut-16 mutants, which disable the piRNA and WAGO-class 22G-RNA pathways respectively. We identified numerous roles for piRNAs and WAGO-class 22G-RNAs in regulating germline genes, including transposons, histones, and spermatogenic and oogenic transcripts.
Project description:The Piwi-piRNA pathway represents a germline specific transposon-defense system. C. elegans Piwi, prg-1, is a non-essential gene and triggers a secondary RNAi response that depends on so-called mutator genes, endo-siRNAs (22G-RNAs) and at least one 22G-RNA-binding Argonaute protein, HRDE-1. Interestingly, through a poorly understood mechanism, silencing of PRG-1 targets can become PRG-1 independent. This state, also known as RNAe, is heritable and depends on mutator genes and HRDE-1. We studied how the transgenerational memory of RNAe and the piRNA pathway interact. We find that maternally provided PRG-1 is required for the de-novo establishment of 22G-RNA populations, especially those targeting transposons. Strikingly, attempts to re-establish 22G-RNAs in absence of both PRG-1 and RNAe memory result in severe germline proliferation defects. This is accompanied by a disturbed balance between gene-activating and -repressing 22G-RNA pathways. We propose a model in which CSR-1 prevents the loading of HRDE-1 and that both PRG-1 and HRDE-1 help to keep mutator activity focused on the proper targets.
