BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Prof. Dr. Gregory Hannon (Cambridge University) DTSTART:20211119T110000Z DTEND:20211119T123000Z DTSTAMP:20260423T022804Z UID:MCB_LUMS/25 DESCRIPTION:Title: A small RNA-based innate immune system guards the integrity of germ cell genomes\nby Prof. Dr. Gregory Hannon (Cambridge University) as part o f Colloquium zooming Molecular & Cellular Biology LUMS\n\n\nAbstract\nPIWI -family proteins and their associated small RNAs (piRNAs) act in an evolut ionarily conserved innate immune mechanism that provides an essential prot ection for germ cell genomes against the activity of mobile genetic elemen ts. piRNA populations comprise a molecular definition of transposons that permits them to be distinguished from host genes and selectively silenced. piRNAs can be generated in two distinct ways. Primary piRNAs emanate from discrete genomic loci\, termed piRNA clusters\, and appear to be derived from long\, single-stranded precursors. The biogenesis of primary piRNAs i nvolves at least two nucleolytic steps. Zucchini cleaves piRNA cluster tra nscripts to generate monophosphorylated piRNA 5’ ends. piRNA 3’ ends a re likely formed by exonucleolytic trimming\, after a piRNA precursor is l oaded into its PIWI partner. Secondary piRNAs arise during the adaptive pi ng-pong cycle\, with their 5’ termini being formed by the activity of PI WIs themselves. At least in Drosophila\, piRNAs are maternally deposited a nd transmit an epigenetic signal essential for the effective control of at least some transposable elements. Our continuing efforts combine genetics \, biochemistry\, structural biology\, and evolutionary and computational approaches to understand how the piRNA pathway effectively discriminates s elf from non-self at the genomic level.\n LOCATION:https://researchseminars.org/talk/MCB_LUMS/25/ END:VEVENT END:VCALENDAR