Epigenetic regulation of nitric oxide synthase 2, inducible (Nos2) by NLRC4 inflammasomes involves PARP1 cleavage.
Nitric oxide synthase 2, inducible (Nos2) expression is necessary for the microbicidal activity of macrophages. However, NOS2 over-activation causes multiple inflammatory disorders, suggesting a tight gene regulation is necessary. Using cytosolic flagellin as a model for inflammasome-dependent NOS2 activation, we discovered a surprising new role for NLRC4/caspase-1 axis in regulating chromatin accessibility of the Nos2 promoter. We found that activation of two independent mechanisms is necessary for NOS2 expression by cytosolic flagellin: caspase-1 and NF-κB activation. NF-κB activation was necessary, but not sufficient, for NOS2 expression. Conversely, caspase-1 was necessary for NOS2 expression, but dispensable for NF-κB activation, indicating that this protease acts downstream NF-κB activation. We demonstrated that epigenetic regulation of Nos2 by caspase-1 involves cleavage of the chromatin regulator PARP1 (also known as ARTD1) and chromatin accessibility of the NF-κB binding sites located at the Nos2 promoter. Remarkably, caspase-1-mediated Nos2 transcription and NO production contribute to the resistance of macrophages to Salmonella typhimurium infection. Our results uncover the molecular mechanism behind the constricted regulation of Nos2 expression and open new therapeutic opportunities based on epigenetic activities of caspase-1 against infectious and inflammatory diseases.
Centro de Terapia Celular e Molecular (CTC-Mol) e Departamento de Ciências Biológicas - Universidade Federal de São Paulo, São Paulo, Brazil.|Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil.
Carina de Lima
CL
Buzzo
Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G 2M9, Canada.
Tiago
T
Medina
Centro de Terapia Celular e Molecular (CTC-Mol) e Departamento de Ciências Biológicas - Universidade Federal de São Paulo, São Paulo, Brazil.|Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo and Instituto de Investigação em Imunologia, Instituto Nacional de Ciência e Tecnologia (INCT-iii), Brazil.
Laura M
LM
Branco
Centro de Terapia Celular e Molecular (CTC-Mol) e Departamento de Ciências Biológicas - Universidade Federal de São Paulo, São Paulo, Brazil.|Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo and Instituto de Investigação em Imunologia, Instituto Nacional de Ciência e Tecnologia (INCT-iii), Brazil.
Silvia L
SL
Lage
Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil.
Luís Carlos de Souza
LC
Ferreira
Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo and Instituto de Investigação em Imunologia, Instituto Nacional de Ciência e Tecnologia (INCT-iii), Brazil.
Gustavo P
GP
Amarante-Mendes
Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland.
Michael O
MO
Hottiger
Princess Margaret Cancer Centre, University Health Network, Toronto, ON, M5G 2M9, Canada.|Department of Medical Biophysics, University of Toronto, Toronto, ON, M5G 2M9, Canada.
Daniel D
DD
De Carvalho
Centro de Terapia Celular e Molecular (CTC-Mol) e Departamento de Ciências Biológicas - Universidade Federal de São Paulo, São Paulo, Brazil.
Karina R
KR
Bortoluci
D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D020170:Caspase 1 / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D044127:Epigenesis, Genetic; D005408:Flagellin / Q000378:metabolism; D005786:Gene Expression Regulation; D058847:Inflammasomes / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics* / Q000378:metabolism; D059372:Nucleotide Motifs; D000071137:Poly (ADP-Ribose) Polymerase-1 / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D059748:Proteolysis
D051017:Apoptosis Regulatory Proteins; D002135:Calcium-Binding Proteins; D058847:Inflammasomes; C512299:Ipaf protein, mouse; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D005408:Flagellin; D052247:Nitric Oxide Synthase Type II; C499321:Parp1 protein, mouse; D000071137:Poly (ADP-Ribose) Polymerase-1; D020170:Caspase 1