Inhibition of CD200R1 expression by C/EBP beta in reactive microglial cells

Dentesano Guido, Straccia Marco, Ejarque-Ortiz Aroa, Tusell, Serratosa Joan, Saura Josep, Solà, Solà Carme

Description

In physiological conditions, it is postulated that neurons control microglial reactivity through a series of inhibitory mechanisms, involving either cell contact-dependent, soluble-factor-dependent or neurotransmitter-associated pathways. In the current study, we focus on CD200R1, a microglial receptor involved in one of these cell contact-dependent mechanisms. CD200R1 activation by its ligand, CD200 (mainly expressed by neurons in the central nervous system),is postulated to inhibit the pro-inflammatory phenotype of microglial cells, while alterations in CD200-CD200R1 signalling potentiate this phenotype. Little is known about the regulation of CD200R1 expression in microglia or possible alterations in the presence of pro-inflammatory stimuli. Methods Murine primary microglial cultures, mixed glial cultures from wild-type and CCAAT/enhancer binding protein β (C/EBPβ)-deficient mice, and the BV2 murine cell line overexpressing C/EBPβ were used to study the involvement of C/EBPβ transcription factor in the regulation of CD200R1 expression in response to a proinflammatory stimulus (lipopolysaccharide (LPS)). Binding of C/EBPβ to the CD200R1 promoter was determined by quantitative chromatin immunoprecipitation (qChIP). The involvement of histone deacetylase 1 in the control of CD200R1 expression by C/EBPβ was also determined by co-immunoprecipitation and qChIP. Results LPS treatment induced a decrease in CD200R1 mRNA and protein expression in microglial cells, an effect that was not observed in the absence of C/EBPβ. C/EBPβ overexpression in BV2 cells resulted in a decrease in basal CD200R1 mRNA and protein expression. In addition, C/EBPβ binding to the CD200R1 promoter was observed in LPS-treated but not in control glial cells, and also in control BV2 cells overexpressing C/EBPβ. Finally, we observed that histone deacetylase 1 co-immunoprecipitated with C/EBPβ and showed binding to a C/EBPβ consensus sequence of the CD200R1 promoter in LPS-treated glial cells. Moreover, histone deacetylase 1 inhibitors reversed the decrease in CD200R1 expression induced by LPS treatment. Conclusions CD200R1 expression decreases in microglial cells in the presence of a pro-inflammatory stimulus, an effect that is regulated, at least in part, by C/EBPβ. Histone deacetylase 1 may mediate C/EBPβ inhibition of CD200R1 expression, through a direct effect on C/EBPβ transcriptional activity and/or on chromatin structure.

Sujets

• CD200R1
• In vitro

Informations

• Publié par: biomed
• Publié le: 01 janvier 2012
• Nombre de lectures: 12
• Langue: English
• Poids de l'ouvrage: 1 Mo

Extrait

Dentesanoet al. Journal of Neuroinflammation2012,9:165 http://www.jneuroinflammation.com/content/9/1/165

JOURNAL OF NEUROINFLAMMATION

R E S E A R C HOpen Access Inhibition of CD200R1 expression by C/EBP beta in reactive microglial cells 1 1,21 11 2 Guido Dentesano , Marco Straccia, Aroa EjarqueOrtiz , Josep M Tusell , Joan Serratosa , Josep Saura 1* and Carme Solà

Abstract Background:In physiological conditions, it is postulated that neurons control microglial reactivity through a series of inhibitory mechanisms, involving either cell contactdependent, solublefactordependent or neurotransmitterassociated pathways. In the current study, we focus on CD200R1, a microglial receptor involved in one of these cell contactdependent mechanisms. CD200R1 activation by its ligand, CD200 (mainly expressed by neurons in the central nervous system),is postulated to inhibit the proinflammatory phenotype of microglial cells, while alterations in CD200CD200R1 signalling potentiate this phenotype. Little is known about the regulation of CD200R1 expression in microglia or possible alterations in the presence of proinflammatory stimuli. Methods:Murine primary microglial cultures, mixed glial cultures from wildtype and CCAAT/enhancer binding proteinβ(C/EBPβ)deficient mice, and the BV2 murine cell line overexpressing C/EBPβwere used to study the involvement of C/EBPβtranscription factor in the regulation of CD200R1 expression in response to a proinflammatory stimulus (lipopolysaccharide (LPS)). Binding of C/EBPβto the CD200R1 promoter was determined by quantitative chromatin immunoprecipitation (qChIP). The involvement of histone deacetylase 1 in the control of CD200R1 expression by C/EBPβwas also determined by coimmunoprecipitation and qChIP. Results:LPS treatment induced a decrease in CD200R1 mRNA and protein expression in microglial cells, an effect that was not observed in the absence of C/EBPβ. C/EBPβoverexpression in BV2 cells resulted in a decrease in basal CD200R1 mRNA and protein expression. In addition, C/EBPβbinding to the CD200R1 promoter was observed in LPStreated but not in control glial cells, and also in control BV2 cells overexpressing C/EBPβ. Finally, we observed that histone deacetylase 1 coimmunoprecipitated with C/EBPβand showed binding to a C/EBPβ consensus sequence of the CD200R1 promoter in LPStreated glial cells. Moreover, histone deacetylase 1 inhibitors reversed the decrease in CD200R1 expression induced by LPS treatment. Conclusions:CD200R1 expression decreases in microglial cells in the presence of a proinflammatory stimulus, an effect that is regulated, at least in part, by C/EBPβ. Histone deacetylase 1 may mediate C/EBPβinhibition of CD200R1 expression, through a direct effect on C/EBPβtranscriptional activity and/or on chromatin structure. Keywords:Neuroinflammation, Reactive microglia, CD200R1, C/EBPβ, Neuronmicroglia communication,In vitro

* Correspondence: [e-mail] 1 Department of Cerebral Ischemia and Neurodegeneration, Institut d’Investigacions Biomèdiques de BarcelonaConsejo Superior de Investigaciones Científicas (CSIC), Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), C/ Rosselló 161, 6th Floor, Barcelona E08036, Spain Full list of author information is available at the end of the article

© 2012 Dentesano et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.