Microprocessor dynamics and interactions at endogenous imprinted C19MC microRNA genes

作者：Bellemer Clement; Bortolin Cavaille Marie Line; Schmidt Ute; Jensen Stig Molgaard Rask; Kjems Jorgen; Bertrand Edouard; Cavaille Jerome^*

来源：Journal of Cell Science, 2012, 125(11): 2709-2720.

DOI：10.1242/jcs.100354

• Intranuclear RNA trafficking
• Transcription sites
• microRNA
• Nuclear architecture
• pri-miRNA processing
• DGCR8-Drosha (Microprocessor) complex

Nuclear primary microRNA (pri-miRNA) processing catalyzed by the DGCR8-Drosha (Microprocessor) complex is highly regulated. Little is known, however, about how microRNA biogenesis is spatially organized within the mammalian nucleus. Here, we image for the first time, in living cells and at the level of a single microRNA cluster, the intranuclear distribution of untagged, endogenously-expressed pri-miRNAs generated at the human imprinted chromosome 19 microRNA cluster (C19MC), from the environment of transcription sites to single molecules of fully released DGCR8-bound pri-miRNAs dispersed throughout the nucleoplasm. We report that a large fraction of Microprocessor concentrates onto unspliced C19MC pri-miRNA deposited in close proximity to their genes. Our live-cell imaging studies provide direct visual evidence that DGCR8 and Drosha are targeted post-transcriptionally to C19MC pri-miRNAs as a preformed complex but dissociate separately. These dynamics support the view that, upon pri-miRNA loading and most probably concomitantly with Drosha-mediated cleavages, Microprocessor undergoes conformational changes that trigger the release of Drosha while DGCR8 remains stably bound to pri-miRNA.

• 出版日期2012-6-1