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Volume 5, Issue 2 (Suppl)
Transcriptomics, an open access journal
ISSN: 2329-8936
Molecular Biology 2017
August 31-September 01, 2017
2
nd
International Conference on
August 31-September 01, 2017 Philadelphia, USA
Molecular Biology, Nucleic Acids &
Molecular Medicine
Panoramix: The missing link between the piRNApathway and the general silencing machinery
Yang Yu
Institute of Biophysics, CAS, China
T
he piwi-interacting RNA (piRNA) pathway is a small RNA-based innate immune system that defends germ cell genomes
against parasitic transposons. In Drosophila ovaries, the nuclear piwi protein is required for transcriptional silencing
of transposons, though the precise mechanisms by which this occurs are unknown. Through mining the data from several
independent genome-wide RNAi screens for factors required for transposon silencing, we identified an ovary specific nuclear
protein (CG9754/Panoramix) that can influence global transposon transcription similarly as piwi when eliminated. The effect
is not due to the defects of piRNA biogenesis since levels of piRNAs remained unchanged and piwi proteins stayed bound
with piRNAs in nucleus. Strikingly, enforced tethering of this protein to nascent mRNA transcripts, causes co-transcriptional
silencing of the source locus (~1000-fold repression) and the deposition of repressive chromatin marks. Interestingly, this
protein is a component of piwi complexes that functions downstream of piwi and its binding partner, Asterix. We have named
this gene Panoramix, the mentor who empowers Asterix to perform his feats of strength. Importantly, we found that both
Eggless/dSetDB1 (H3K9 methyltransferase) and dLSD1 (H3K4me2 demethylase) are required for Panoramix-mediated
silencing. Therefore, we propose that Panoramix forms one of the missing links between the piRNA pathway and the general
silencing machinery that it recruits to enforce transcriptional repression to protect germline from transposons.
yuyang@ibp.ac.cnTranscriptomics 2017, 5:2 (Suppl)
DOI: 10.4172/2329-8936-C1-013