title: Tristetraprolin regulates CXCL1 (KC) mRNA stability.
abstract: mRNAs encoding proinflammatory chemokines are regulated posttranscriptionally via adenine-uridine-rich sequences (AREs) located in the 3' untranslated region of the message, which are recognized by sequence-specific RNA-binding proteins. One ARE binding protein, tristetraprolin (TTP), has been implicated in regulating the stability of several ARE-containing mRNAs, including those encoding TNF-alpha and GM-CSF. In the present report we examined the role of TTP in regulating the decay of the mouse chemokine KC (CXCL1) mRNA. Using tetR-regulated control of transcription in TTP-deficient HEK293 cells, KC mRNA half-life was markedly decreased in the presence of TTP. Deletion and site-specific mutagenesis were used to identify multiple AUUUA sequence determinants responsible for TTP sensitivity. Although a number of studies suggest that the destabilizing activity of TTP is subject to modulation in response to ligands of Toll/IL-1 family receptors, decay mediated by TTP in 293 cells was not sensitive to stimulation with IL-1alpha. Using primary macrophages from wild-type and TTP-deficient mice, KC mRNA instability was found to be highly dependent on TTP. Furthermore, LPS-mediated stabilization of KC mRNA is blocked by inhibition of the p38 MAPK in macrophages from wild-type but not TTP-deficient mice. These findings demonstrate that TTP is the predominant regulator of KC mRNA decay in mononuclear phagocytes acting via multiple 3'-untranslated region-localized AREs. Nevertheless, KC mRNA remains highly unstable in cells that do not express TTP, suggesting that additional determinants of instability and stimulus sensitivity may operate in cell populations where TTP is not expressed.
authors.affiliation: Department of Immunology, Lerner Research Institute, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
authors.forename: Shyamasree
authors.initials: S
authors.lastname: Datta
authors.forename: Roopa
authors.initials: R
authors.lastname: Biswas
authors.forename: Michael
authors.initials: M
authors.lastname: Novotny
authors.forename: Paul G
authors.initials: PG
authors.lastname: Pavicic
authors.forename: Tomasz
authors.initials: T
authors.lastname: Herjan
authors.forename: Palash
authors.initials: P
authors.lastname: Mandal
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Hamilton
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics / Q000276:immunology; D000225:Adenine / Q000502:physiology; D020816:Amino Acid Motifs / Q000235:genetics / Q000276:immunology; D000818:Animals; D002460:Cell Line; D054360:Chemokine CXCL1 / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D008264:Macrophages / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016297:Mutagenesis, Site-Directed; D020871:RNA Stability / Q000235:genetics / Q000276:immunology*; D012333:RNA, Messenger / Q000378:metabolism*; D012097:Repressor Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics / Q000276:immunology; D051816:Tristetraprolin / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D014529:Uridine / Q000502:physiology
chemical_list: D020413:3' Untranslated Regions; C475829:CXCL1 protein, human; D054360:Chemokine CXCL1; C475895:Cxcl1 protein, mouse; D012333:RNA, Messenger; D012097:Repressor Proteins; D051816:Tristetraprolin; C497552:ZFP36 protein, human; C034811:tetracycline resistance-encoding transposon repressor protein; D000225:Adenine; D014529:Uridine