Citrullination-acetylation interplay guides E2F-1 activity during the inflammatory response

Ghari, Fatemeh; Quirke, Anne‐Marie; Munro, Shonagh; Kawalkowska, Joanna; Picaud, S.; McGouran, Joanna F.; Subramanian, Venkataraman; Muth, Aaron; Williams, Richard O.; Kessler, Benedikt M.; Thompson, Paul R.; Fillipakopoulos, Panagis; Knapp, Stefan; Venables, P. J. W.; Thangué, Nicholas B. La

doi:10.1126/sciadv.1501257

Cited by 65 publications

(76 citation statements)

References 29 publications

(38 reference statements)

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“…In addition, the transient transfection assay shown in Figure 2E and 2F is not subjected to epigenetic regulation. Furthermore, Ghari et al showed that citrullination of the transcription factor E2F facilitated its binding with BRD4 (bromodomain-containing protein 4) and recruitment to the promoter of several inflammatory cytokine genes, including IL-1β and TNFα, thereby augmenting the expression of these cytokines (37). Thus, citrullination can regulate the expression of IL-1β and TNFα by more than one mechanism: epigenetically modifying their genetic loci, facilitating the recruitment of E2F to their promoters, and promoting the nuclear translocation of p65.…”

Section: Discussionmentioning

confidence: 99%

Citrullination of NF-κB p65 promotes its nuclear localization and TLR-induced expression of IL-1β and TNFα

et al. 2017

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Citrullination converts peptidyl-arginine to peptidyl-citrulline and is mediated by the enzymes peptidyl arginine deiminases (PADs), including PAD1–4 and PAD6. The physiological role of citrullination in immune cells is poorly understood. Here we report that suppression of PAD activity attenuates TLR-induced expression of IL-1β and TNFα by neutrophils in vivo and in vitro but not their global transcription activity. Mechanistically, PAD4 directly citrullinates NF-kB p65 and enhances the interaction of p65 with importin α3, which brings p65 into the nucleus. The citrullination-enhanced interaction of p65 with importin α3, and its nuclear translocation and transcriptional activity can be attributed to citrullination of four arginine residues located in the Rel homology domain of p65. Furthermore, a rheumatoid arthritis-prone variant of PAD4, carrying three missense mutations, is more efficient in interacting with p65 and enhancing NF-kB activity. Together, these data demonstrate a critical role of citrullination in NF-kB-dependent expression of IL-1β and TNFα.

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Section: Discussionmentioning

confidence: 99%

Citrullination of NF-κB p65 promotes its nuclear localization and TLR-induced expression of IL-1β and TNFα

et al. 2017

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“…Peptidylarginine deiminase type 4 plays a major role in epigenetic regulation via the citrullination of histones and transcription factors (72–74, 89–95). In the immune system, PAD4 promotes cytokine production by augmenting chromatin association of E2F-1 and decreasing HP1-mediated transcriptional repression of cytokine genes (74, 89).…”

Section: Introductionmentioning

confidence: 99%

A Critical Reappraisal of Neutrophil Extracellular Traps and NETosis Mimics Based on Differential Requirements for Protein Citrullination

2016

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NETosis, an antimicrobial form of neutrophil cell death, is considered a primary source of citrullinated autoantigens in rheumatoid arthritis (RA) and immunogenic DNA in systemic lupus erythematosus (SLE). Activation of the citrullinating enzyme peptidylarginine deiminase type 4 (PAD4) is believed to be essential for neutrophil extracellular trap (NET) formation and NETosis. PAD4 is therefore viewed as a promising therapeutic target to inhibit the formation of NETs in both diseases. In this review, we examine the evidence for PAD4 activation during NETosis and provide experimental data to suggest that protein citrullination is not a universal feature of NETs. We delineate two distinct biological processes, leukotoxic hypercitrullination (LTH) and defective mitophagy, which have been erroneously classified as “NETosis.” While these NETosis mimics share morphological similarities with NETosis (i.e., extracellular DNA release), they are biologically distinct. As such, these processes can be readily classified by their stimuli, activation of distinct biochemical pathways, the presence of hypercitrullination, and antimicrobial effector function. NETosis is an antimicrobial form of cell death that is NADPH oxidase-dependent and not associated with hypercitrullination. In contrast, LTH is NADPH oxidase-independent and not bactericidal. Rather, LTH represents a bacterial strategy to achieve immune evasion. It is triggered by pore-forming pathways and equivalent signals that cumulate in calcium-dependent hyperactivation of PADs, protein hypercitrullination, and neutrophil death. The generation of citrullinated autoantigens in RA is likely driven by LTH, but not NETosis. Mitochondrial DNA (mtDNA) expulsion, the result of a constitutive defect in mitophagy, represents a second NETosis mimic. In the presence of interferon-α and immune complexes, this process can generate highly interferogenic oxidized mtDNA, which has previously been mistaken for NETosis in SLE. Distinguishing NETosis from LTH and defective mitophagy is paramount to understanding the role of neutrophil damage in immunity and the pathogenesis of human diseases. This provides a framework to design specific inhibitors of these distinct biological processes in human disease.

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“…18 Furthermore, a recent peptide array study of BRD4-BD1 and BRD4-BD2 binding to the acetylated transcription factor E2F-1 by Ghari et al demonstrated that binding of both BRD4 bromodomains was enhanced when a positively charged arginine residue next to the acetylation site was converted to a neutral citrulline residue, thereby demonstrating the detrimental effect of neighboring positive charge to the acetyl-lysine site on BET bromodomain binding. 9 To investigate if our hypothesis is correct that all acylations at H4K8 enhance BRDT-BD1 and BRD4-BD1 binding to H4K5acetyl, a series of histone H4 peptides monoacetylated at H4K5 and either unmodified or modified with a non-acetyl acylation at H4K8 were synthesized. Relative to the binding affinity of the monoacetylated H4K5acetyl peptide to BRD4-BD1 ( K d = 129 ± 22 μM), acylation of H4K8 (H4K5acetylK8acyl) increased the binding affinity of BRD4-BD1 ≥1.4-fold with K d values ranging from 17 to 92 μM, comparable to that of the diacetylated H4K5/8diacetyl peptide ( K d = 55 ± 7 μM) (Figure 4C; Table 3).…”

Section: Resultsmentioning

confidence: 97%

“…4 Towards this end, a handful of histone acetylation sites have been demonstrated to bind BET bromodomains with varying degrees of confidence. 1, 5–9 BET bromodomain binding affinity has also been shown to be regulated combinatorially by neighboring serine/threonine phosphorylation and lysine/arginine methylation within histone H3 as well as arginine citrullination within E2F-1. 1, 9 However, the effects of neighboring modifications on BET bromodomain binding to the histone H4 N -terminal tail, hypothesized to be the primary binding partner of the N- terminal (BD1) BET bromodomains, 1, 6 remain unclear.…”

Section: Introductionmentioning

confidence: 99%

Metabolically Derived Lysine Acylations and Neighboring Modifications Tune the Binding of the BET Bromodomains to Histone H4

2017

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Recent proteomic studies discovered histone lysines are modified by acylations beyond acetylation. These acylations derive from acyl-CoA metabolites, potentially linking metabolism to transcription. Bromodomains bind lysine acylation on histones and other nuclear proteins to influence transcription. However, the extent bromodomains bind non-acetyl acylations is largely unknown. Also unclear are the effects of neighboring post-translational modifications, especially within heavily modified histone tails. Using peptide arrays, binding assays, sucrose gradients, and computational methods, we quantified ten distinct acylations for binding to the bromodomain and extraterminal domain (BET) family. Four of these acylations – hydroxyisobutyrylation, malonylation, glutarylation, and homocitrullination – had never been tested for bromodomain binding. We found N-terminal BET bromodomains bound acetylated and propionylated peptides consistent with previous studies. Interestingly, all other acylations inhibited BET bromodomain binding to peptides and nucleosomes. To understand how context tunes bromodomain binding, effects of neighboring methylation, phosphorylation, and acylation within histone H4 tails were determined. Serine-1 phosphorylation inhibited BRD4 N-terminal bromodomain binding to polyacetylated H4 tails by >5-fold whereas methylation had no effect. Furthermore, BRDT and BRD4 N-terminal bromodomain binding to H4K5acetyl was enhanced 1.4- to 9.5-fold by any neighboring acylation of lysine-8, indicating a secondary H4K8acyl binding site that is more permissive of non-acetyl acylations than previously appreciated. In contrast, C-terminal BET bromodomains exhibited 9.9- to 13.5-fold weaker binding for polyacylated compared to monoacylated H4 tails indicating the C-terminal bromodomains do not cooperatively bind multiple acylations. These results suggest acyl-CoA levels tune or block BET bromodomain recruitment to histones, linking metabolism to bromodomain-mediated transcription.

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Citrullination-acetylation interplay guides E2F-1 activity during the inflammatory response

Abstract: PAD4-mediated citrullination of E2F-1 transcription factor and its interplay with acetylation affects inflammatory gene expression.

Cited by 65 publications

References 29 publications

Citrullination of NF-κB p65 promotes its nuclear localization and TLR-induced expression of IL-1β and TNFα

Citrullination of NF-κB p65 promotes its nuclear localization and TLR-induced expression of IL-1β and TNFα

A Critical Reappraisal of Neutrophil Extracellular Traps and NETosis Mimics Based on Differential Requirements for Protein Citrullination

Metabolically Derived Lysine Acylations and Neighboring Modifications Tune the Binding of the BET Bromodomains to Histone H4

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