title: Characterization of nuclear factors modulating the apolipoprotein D promoter during growth arrest: implication of PARP-1, APEX-1 and ERK1/2 catalytic activities.
abstract: Human Apolipoprotein D (apoD) is upregulated under several stress conditions and pathological situations such as neurodegenerative diseases and cancers. We previously showed that apoD mRNA expression is induced in growth-arrested cells and demonstrated the specific binding of nuclear proteins to the region -514 to -475 of the promoter. Such region contains a pair of Serum Responsive Elements (SRE), an Ets-Binding Site (EBS) and a Glucocorticoid Responsive Element (GRE). In this study, we show that Parp-1, HnRNP-U, CBF-A, BUB-3, Kif4, APEX-1 and Ifi204 bind these regulatory elements of the apoD promoter. Specific binding of HnRNP-U and Parp-1 was confirmed by Electrophoretic Mobility Shift Assay (EMSA). In a biotin pull-down assay, Kif4 and BUB-3 bind preferentially the SRE1 and the EBS-GRE sites, respectively, while APEX-1 seems recruited indirectly to these elements. We found that the mRNA expression of some of these binding factors is upregulated in growth-arrested cells and that these proteins also transactivate the apoD promoter. In agreement with these results, mutants of APEX-1 and of Parp-1 defective for their DNA-binding and catalytic activities could not transactivate the promoter. The knockdown of Parp-1 and HnRNP-U and the use of specific inhibitors of MEK1/2 and of Parp-1 also inhibited the induction of apoD gene expression. Moreover, ERK1/2 was found activated in a biphasic manner post serum-starvation and the inhibition of Parp-1 causes a sustained activation of ERK2 but not ERK1 for up to 2h. Altogether, these findings demonstrate the importance of Parp-1, APEX-1 and ERK1/2 catalytic activities in the growth arrest-induced apoD gene expression.
authors.affiliation: Laboratoire de biologie moléculaire, Département des Sciences Biologiques, and Centre BioMed, Université du Québec à Montréal, Montréal, Québec, Canada.
authors.forename: Louis-Charles
authors.initials: LC
authors.lastname: Levros
authors.forename: Sonia
authors.initials: S
authors.lastname: Do Carmo
authors.forename: Elsy
authors.initials: E
authors.lastname: Edouard
authors.forename: Philippe
authors.initials: P
authors.lastname: Legault
authors.forename: Cyndia
authors.initials: C
authors.lastname: Charfi
authors.forename: Eric
authors.initials: E
authors.lastname: Rassart
mesh_terms: D000818:Animals; D053399:Apolipoproteins D / Q000235:genetics*; D002384:Catalysis; D002453:Cell Cycle / Q000235:genetics; D048708:Cell Growth Processes / Q000235:genetics*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000378:metabolism / Q000502:physiology*; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D006023:Glycoproteins / Q000235:genetics*; D006801:Humans; D026901:Membrane Transport Proteins / Q000235:genetics*; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism / Q000502:physiology*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism / Q000502:physiology; D041681:NIH 3T3 Cells; D009687:Nuclear Proteins / Q000378:metabolism / Q000502:physiology; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism / Q000502:physiology*; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology
chemical_list: C024328:APOD protein, human; D053399:Apolipoproteins D; D006023:Glycoproteins; D026901:Membrane Transport Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase