Research on Piwi proteins and piRNAs

Mobile DNA accounts for a large fraction of mammalian genomes. Retroposons of endogenous (e.g. Alu elements) or exogenous (e.g. HERV) origin steadily increased in copy number by applying a “copy-paste”-like cloning mechanism for their own propagation throughout the host genome.

Different classes of primate retroposons are still active and constitute a steady threat to genome integrity by potentially disrupting essential genes and providing the prerequisite for ectopic recombination. Throughout the metazoan lineage, organisms have established a molecular defense mechanism that employes Piwi proteins and a broad arsenal of small noncoding RNAs (Piwi-interacting RNAs, piRNAs) to track down hostile retroposon intermediates. On the other hand, new classes of retroposons arised and existing retroposons constantly diversified over evolutionary timespans thus eluding the established host resistence.

Our research intends to throw light on the adaptations of Piwi proteins, piRNAs and genomic piRNA-clusters that ensure the maintenance of a functional retroposon defense. We aim to figure out different patterns of subfunctionalization/specialization regarding single components of the Piwi/piRNA pathway in different species that may reflect the specific activity of the particular retroposon repertoire.

Recommendations for further reading:

Ishizu H, Siomi H, Siomi MC. Biology of PIWI-interacting RNAs: new insights into biogenesis and function inside and outside of germlines. Genes Dev. 2012 26(21):2361-2373.

Bamezai S, Rawat VP, Buske C. Concise Review: The Piwi-piRNA Axis: Pivotal Beyond Transposon Silencing. Stem Cells. 2012 30(12):2603-2611.

Rosenkranz D, Zischler H. proTRAC - a software for probabilistic piRNA cluster detection, visualization and analysis. BMC Bioinformatics. 2012 13:5.

Siomi MC, Sato K, Pezic D, Aravin AA. PIWI-interacting small RNAs: the vanguard of genome defence. Nat Rev Mol Cell Biol. 2011 12(4):246-258.

Thomson T, Lin H. The biogenesis and function of PIWI proteins and piRNAs: progress and prospect. Annu Rev Cell Dev Biol. 2009 25:355-376.