How does the piRNA pathway – a small non-coding RNA pathway – regulate transcription and chromatin structure?

Chromatin structure plays a key role in regulating expression of the underlying genomic sequence. Yet we know little about the molecular basis of establishing diverse chromatin states on different genomic regions. Non-coding RNAs are emerging as key regulators of gene expression and are crucial for survival, development and differentiation. They can serve to convey sequence-specificity to regulatory processes. In animals, small RNAs were mostly associated with post-transcriptional regulation through a phenomenon termed RNA interference or RNAi. Our recent studies have revealed that a germline specific small RNA pathway, the piRNA pathway, also acts to regulate transcription by directing establishment of a repressive chromatin over its genomic targets. Our goal is to elucidate the exact mechanism through which the piRNA pathway induces transcriptional repression by identifying key factors in this silencing process and by elucidating their functions.