title: Post-transcriptional regulation of Wnt co-receptor LRP6 and RNA-binding protein HuR by miR-29b in intestinal epithelial cells.
abstract: MicroRNAs (miRNAs) control gene expression by binding to their target mRNAs for degradation and/or translation repression and are implicated in many aspects of cellular physiology. Our previous study shows that miR-29b acts as a biological repressor of intestinal mucosal growth, but its exact downstream targets remain largely unknown. In the present study, we found that mRNAs, encoding Wnt co-receptor LRP6 (low-density lipoprotein-receptor-related protein 6) and RNA-binding protein (RBP) HuR, are novel targets of miR-29b in intestinal epithelial cells (IECs) and that expression of LRP6 and HuR is tightly regulated by miR-29b at the post-transcriptional level. miR-29b interacted with both Lrp6 and HuR mRNAs via their 3'-UTRs and inhibited LRP6 and HuR expression by destabilizing Lrp6 and HuR mRNAs and repressing their translation. Studies using heterologous reporter constructs revealed a greater repressive effect of miR-29b through a single binding site in the Lrp6 or HuR 3'-UTR, whereas deletion mutation of this site prevented miR-29b-induced repression of LRP6 and HuR expression. Repression of HuR by miR-29b in turn also contributed to miR-29b-induced LRP6 inhibition, since ectopic overexpression of HuR in cells overexpressing miR-29b restored LRP6 expression to near normal levels. Taken together, our results suggest that miR-29b inhibits expression of LRP6 and HuR post-transcriptionally, thus playing a role in the regulation of IEC proliferation and intestinal epithelial homoeostasis.
authors.affiliation: Cell Biology Group, Department of Surgery, Baltimore, MD 21201, U.S.A. Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201, U.S.A.
authors.forename: Yanwu
authors.initials: Y
authors.lastname: Li
authors.affiliation: Cell Biology Group, Department of Surgery, Baltimore, MD 21201, U.S.A. Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201, U.S.A.
authors.forename: Gang
authors.initials: G
authors.lastname: Chen
authors.affiliation: Cell Biology Group, Department of Surgery, Baltimore, MD 21201, U.S.A. Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201, U.S.A.
authors.forename: Jun-Yao
authors.initials: JY
authors.lastname: Wang
authors.affiliation: Cell Biology Group, Department of Surgery, Baltimore, MD 21201, U.S.A. Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201, U.S.A.
authors.forename: Tongtong
authors.initials: T
authors.lastname: Zou
authors.affiliation: Cell Biology Group, Department of Surgery, Baltimore, MD 21201, U.S.A. Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201, U.S.A.
authors.forename: Lan
authors.initials: L
authors.lastname: Liu
authors.affiliation: Cell Biology Group, Department of Surgery, Baltimore, MD 21201, U.S.A. Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201, U.S.A.
authors.forename: Lan
authors.initials: L
authors.lastname: Xiao
authors.affiliation: Cell Biology Group, Department of Surgery, Baltimore, MD 21201, U.S.A. Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201, U.S.A.
authors.forename: Hee Kyoung
authors.initials: HK
authors.lastname: Chung
authors.affiliation: Cell Biology Group, Department of Surgery, Baltimore, MD 21201, U.S.A. Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201, U.S.A.
authors.forename: Jaladanki N
authors.initials: JN
authors.lastname: Rao
authors.affiliation: Cell Biology Group, Department of Surgery, Baltimore, MD 21201, U.S.A. Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201, U.S.A. Department of Pathology, University of Maryland School of Medicine, Baltimore, MD 21201, U.S.A. jwang@smail.umaryland.edu.
authors.forename: Jian-Ying
authors.initials: JY
authors.lastname: Wang
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D018938:Caco-2 Cells; D000067780:ELAV-Like Protein 1 / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D007422:Intestines / Q000166:cytology*; D060488:Low Density Lipoprotein Receptor-Related Protein-6 / Q000235:genetics / Q000378:metabolism*; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D020413:3' Untranslated Regions; D000067780:ELAV-Like Protein 1; C555475:LRP6 protein, human; D060488:Low Density Lipoprotein Receptor-Related Protein-6; C532045:MIRN29a microRNA, human; D035683:MicroRNAs; D012333:RNA, Messenger
keywords: Wnt signalling; intestinal epithelial homoeostasis; mRNA stability; non-coding RNAs; translation