title: Regulation of thrombospondin-1 expression through AU-rich elements in the 3'UTR of the mRNA.
abstract: Thrombospondin-1 (TSP-1) is a matricellular protein that participates in numerous normal and pathological tissue processes and is rapidly modulated by different stimuli. The presence of 8 highly-conserved AU rich elements (AREs) within the 3'-untranslated region (3'UTR) of the TSP-1 mRNA suggests that post-transcriptional regulation is likely to represent one mechanism by which TSP-1 gene expression is regulated. We investigated the roles of these AREs, and proteins which bind to them, in the control of TSP-1 mRNA stability. The endogenous TSP-1 mRNA half-life is approximately 2.0 hours in HEK293 cells. Luciferase reporter mRNAs containing the TSP-1 3'UTR show a similar rate of decay, suggesting that the 3'UTR influences the decay rate. Site-directed mutagenesis of individual and adjacent AREs prolonged reporter mRNA halflife to between 2.2 and 4.4 hours. Mutation of all AREs increased mRNA half life to 8.8 hours, suggesting that all AREs have some effect, but that specific AREs may have key roles in stability regulation. A labeled RNA oligonucleotide derived from the most influential ARE was utilized to purify TSP-1 ARE-binding proteins. The AU-binding protein AUF1 was shown to associate with this motif. These studies reveal that AREs in the 3'UTR control TSP-1 mRNA stability and that the RNA binding protein AUF1 participates in this control. These studies suggest that ARE-dependent control of TSP-1 mRNA stability may represent an important component in the control of TSP-1 gene expression.
authors.affiliation: Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, N1G 2W1, Canada.
authors.forename: Asa J Robert
authors.initials: AJ
authors.lastname: McGray
authors.forename: Timothy
authors.initials: T
authors.lastname: Gingerich
authors.forename: James J
authors.initials: JJ
authors.lastname: Petrik
authors.forename: Jonathan
authors.initials: J
authors.lastname: Lamarre
mesh_terms: D020413:3' Untranslated Regions; D001483:Base Sequence; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006207:Half-Life; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D016297:Mutagenesis, Site-Directed; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism; D019700:Thrombospondin 1 / Q000235:genetics* / Q000378:metabolism
chemical_list: D020413:3' Untranslated Regions; C000630986:HNRNPD protein, human; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D; D012333:RNA, Messenger; D019700:Thrombospondin 1