Stability of casein mRNA is ensured by structural interactions between the 3'-untranslated region and poly(A) tail via the HuR and poly(A)-binding protein complex.
The maintenance of mRNA stability has emerged as a mechanism of post-transcriptional control. We demonstrate that beta-casein mRNA stability is dictated by the poly(A) tail and sequences in the 3'-UTR. An in vitro mRNA decay assay revealed that beta-casein mRNA with a long poly(A) tail had higher stability than that with a short poly(A) tail. The addition of poly(A) homopolymer and 3'-UTR cRNA as competitor induced rapid degradation of beta-casein mRNA. The interaction between full-length beta-casein mRNA and poly(A) homopolymer was inhibited by the addition of the 3'-UTR cRNA in the lysates, which indicates that one region of the 3'-UTR associates with the poly(A) tail through an RNA-protein interaction. The putative AU-rich element (ARE) is present at nt 897-905; deletion and mutation analysis showed that the ARE site was required for maintaining the stability of the beta-casein 3'-UTR. In the immunoprecipitation analysis, the poly(A)-binding protein (PABP) and the RNA-binding protein HuR were pulled down by 3'-UTR cRNA, and the absence of the ARE site reduced the binding of these proteins. These experiments further revealed that the rapid degradation of beta-casein mRNA was induced by incubation with HuR- and PABP-depleted RRLs. Collectively, our results suggest that beta-casein mRNA is protected from degradation by virtue of the structural interaction between the 3'-UTR and poly(A) tail via a protein complex of HuR and PABP.
Nagaoka
Kentaro
K
Laboratory of Animal Breeding, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Tokyo 113-8657, Japan. akenaga@mail.ecc.u-tokyo.ac.jp
Suzuki
Toshiyuki
T
Kawano
Tomomi
T
Imakawa
Kazuhiko
K
Sakai
Senkiti
S
D020413:3' Untranslated Regions / Q000235:genetics*; D000818:Animals; D000954:Antigens, Surface / Q000737:chemistry / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D002364:Caseins / Q000235:genetics*; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; D051379:Mice; D009154:Mutation / Q000235:genetics; D041681:NIH 3T3 Cells; D039102:Poly(A)-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D020871:RNA Stability / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*
D020413:3' Untranslated Regions; D000954:Antigens, Surface; D002352:Carrier Proteins; D002364:Caseins; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; C098770:ELAVL1 protein, human; D039102:Poly(A)-Binding Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins