title: Identification of a signature motif in target mRNAs of RNA-binding protein AUF1.
abstract: The ubiquitous RNA-binding protein AUF1 promotes the degradation of some target mRNAs, but increases the stability and translation of other targets. Here, we isolated AUF1-associated mRNAs by immunoprecipitation of (AUF1-RNA) ribonucleoprotein (RNP) complexes from HeLa cells, identified them using microarrays, and used them to elucidate a signature motif shared among AUF1 target transcripts. The predicted AUF1 motif (29-39 nucleotides) contained 79% As and Us, consistent with the AU-rich sequences of reported AUF1 targets. Importantly, 10 out of 15 previously reported AUF1 target mRNAs contained the AUF1 motif. The predicted interactions between AUF1 and target mRNAs were recapitulated in vitro using biotinylated RNAs. Interestingly, further validation of predicted AUF1 target transcripts revealed that AUF1 associates with both the pre-mRNA and the mature mRNA forms. The consequences of AUF1 binding to 10 predicted target mRNAs were tested by silencing AUF1, which elevated the steady-state levels of only four mRNAs, and by overexpressing AUF1, which also lowered the levels of only four mRNAs. In total, we have identified a signature motif in AUF1 target mRNAs, have found that AUF1 also associates with the corresponding pre-mRNAs, and have discovered that altering AUF1 levels alone only modifies the levels of subsets of target mRNAs.
authors.affiliation: Laboratory of Cellular and Molecular Biology, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA.
authors.forename: Krystyna
authors.initials: K
authors.lastname: Mazan-Mamczarz
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kuwano
authors.forename: Ming
authors.initials: M
authors.lastname: Zhan
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: White
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Martindale
authors.forename: Ashish
authors.initials: A
authors.lastname: Lal
authors.forename: Myriam
authors.initials: M
authors.lastname: Gorospe
mesh_terms: D020413:3' Untranslated Regions / Q000737:chemistry; D001483:Base Sequence; D001665:Binding Sites; D006367:HeLa Cells; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012322:RNA Precursors / Q000737:chemistry / Q000378:metabolism; D020871:RNA Stability; D012333:RNA, Messenger / Q000737:chemistry* / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid
chemical_list: D020413:3' Untranslated Regions; C000630986:HNRNPD protein, human; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D; D012322:RNA Precursors; D012333:RNA, Messenger