RNA-Direct Regulation of pri-miRNA Processing by a Long Noncoding RNA Transcribed from an Ultraconserved Region

We investigate the role of a long ncRNA transcribed from an ultraconserved region (T-UCR) in the control of post-transcriptional pri-miRNA processing. The regulation is based on complementarity between the lower stem region in pri-miR-195 transcript and the ultraconserved sequence in Uc.283+A, which prevents pri-miRNA cleavage by Drosha. Mutation of the site in either RNA molecule uncouples regulation in vivo and in vitro. We propose a model in which lower-stem strand invasion by Uc.283+A impairs microprocessor recognition and efficient pri-miRNA cropping. In this work, we characterize a new role for Uc.283+A as a direct interactor and regulator of pri-miRNA-195 maturation at the level of Drosha processing. We combine cellular assays with in vitro biochemical analyses to reveal the first case of RNA-directed downregulation of miRNA biogenesis by a T-UCR In the study presented here, a colorrectal cancer cell line (HCT-116) was transiently transfected with Uc.283+A in order to identify putative miRNA targets for Uc.283+A. Variant 1 represents a SNP variant (8x(T) repeat in the sequence). Variant 2 represents a SNP variant (9x(T) repeat in the sequence).