Regulation of tyrosine hydroxylase mRNA stability by protein-binding, pyrimidine-rich sequence in the 3'-untranslated region.
The stability of mRNA for tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine synthesis, is regulated by oxygen tension in the pheochromocytoma-derived PC12 cell line. We previously identified a pyrimidine-rich 27-base-long protein-binding sequence in the 3'-untranslated region of TH mRNA that is associated with hypoxia-inducible formation of a ribonucleoprotein complex (hypoxia-inducible protein-binding site (HIPBS)). In this study, we show that HIPBS is an mRNA stabilizing element necessary for both constitutive and hypoxia-regulated stability of TH mRNA. The mutations within this sequence that abolish protein binding markedly decrease constitutive TH mRNA stability and ablate its hypoxic regulation. A short fragment of TH mRNA that contains the wild-type HIPBS confers the increased mRNA stability to the reporter chloramphenicol acetyltransferase mRNA. However, it is not sufficient to confer hypoxic regulation. The HIPBS element binds two isoforms of a 40-kDa poly(C)-binding protein (PCBP). Hypoxia induces expression of the isoform 1, PCBP1, but not the isoform 2, PCBP2, in PC12 cells.
Paulding
W R
WR
Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0576, USA.
Czyzyk-Krzeska
M F
MF
D020413:3' Untranslated Regions; D000818:Animals; D015687:Cell Hypoxia; D004268:DNA-Binding Proteins / Q000378:metabolism; D004795:Enzyme Stability; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism; D016716:PC12 Cells; D011485:Protein Binding; D011743:Pyrimidines / Q000737:chemistry / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D014157:Transcription Factors; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics*
D020413:3' Untranslated Regions; D004268:DNA-Binding Proteins; C497444:Hif1a protein, rat; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009687:Nuclear Proteins; D011743:Pyrimidines; D012333:RNA, Messenger; D014157:Transcription Factors; D014446:Tyrosine 3-Monooxygenase