title: Characterizing HSF1 Binding and Post-Translational Modifications of hsp70 Promoter in Cultured Cortical Neurons: Implications in the Heat-Shock Response.
abstract: Causes of lower induction of Hsp70 in neurons during heat shock are still a matter of debate. To further inquire into the mechanisms regulating Hsp70 expression in neurons, we studied the activity of Heat Shock Factor 1 (HSF1) and histone posttranslational modifications (PTMs) at the hsp70 promoter in rat cortical neurons. Heat shock induced a transient and efficient translocation of HSF1 to neuronal nuclei. However, no binding of HSF1 at the hsp70 promoter was detected while it bound to the hsp25 promoter in cortical neurons during heat shock. Histone PTMs analysis showed that the hsp70 promoter harbors lower levels of histone H3 and H4 acetylation in cortical neurons compared to PC12 cells under basal conditions. Transcriptomic profiling data analysis showed a predominant usage of cryptic transcriptional start sites at hsp70 gene in the rat cerebral cortex, compared with the whole brain. These data support a weaker activation of hsp70 canonical promoter. Heat shock increased H3Ac at the hsp70 promoter in PC12 cells, which correlated with increased Hsp70 expression while no modifications occurred at the hsp70 promoter in cortical neurons. Increased histone H3 acetylation by Trichostatin A led to hsp70 mRNA and protein induction in cortical neurons. In conclusion, we found that two independent mechanisms maintain a lower induction of Hsp70 in cortical neurons. First, HSF1 fails to bind specifically to the hsp70 promoter in cortical neurons during heat shock and, second, the hsp70 promoter is less accessible in neurons compared to non-neuronal cells due to histone deacetylases repression.
authors.affiliation: Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, Santiago, Chile.
authors.forename: Andrea V
authors.initials: AV
authors.lastname: Gómez
authors.affiliation: Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, Santiago, Chile.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Córdova
authors.affiliation: Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, Santiago, Chile.
authors.forename: Roberto
authors.initials: R
authors.lastname: Munita
authors.affiliation: Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, Santiago, Chile.
authors.forename: Guillermo E
authors.initials: GE
authors.lastname: Parada
authors.affiliation: Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, Santiago, Chile.
authors.forename: Álvaro P
authors.initials: ÁP
authors.lastname: Barrios
authors.affiliation: Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, Santiago, Chile.
authors.forename: Gonzalo I
authors.initials: GI
authors.lastname: Cancino
authors.affiliation: Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, Santiago, Chile.
authors.forename: Alejandra R
authors.initials: AR
authors.lastname: Álvarez
authors.affiliation: Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, Santiago, Chile.
authors.forename: María E
authors.initials: ME
authors.lastname: Andrés
mesh_terms: D000107:Acetylation; D000818:Animals; D002540:Cerebral Cortex / Q000166:cytology*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D020869:Gene Expression Profiling; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D000076249:Heat Shock Transcription Factors; D018869:Heat-Shock Response / Q000235:genetics*; D006657:Histones / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D016716:PC12 Cells; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000235:genetics; D011499:Protein Processing, Post-Translational; D051381:Rats; D017207:Rats, Sprague-Dawley; D014157:Transcription Factors / Q000378:metabolism*; D024363:Transcription Initiation Site; D059467:Transcriptome / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D006657:Histones; C000619709:Hsf1 protein, rat; D014157:Transcription Factors