Abstract

Inflammasomes are multimolecular complexes with potent inflammatory activity. As such, their activity is tightly regulated at the transcriptional and post-transcriptional levels. In this review, we present the transcriptional regulation of inflammasome genes from sensors (e.g., NLRP3) to substrates (e.g., IL-1β). Lineage-determining transcription factors shape inflammasome responses in different cell types with profound consequences on the responsiveness to inflammasome-activating stimuli. Pro-inflammatory signals (sterile or microbial) have a key transcriptional impact on inflammasome genes, which is largely mediated by NF-κB and that translates into higher antimicrobial immune responses. Furthermore, diverse intrinsic (e.g., circadian clock, metabolites) or extrinsic (e.g., xenobiotics) signals are integrated by signal-dependent transcription factors and chromatin structure changes to modulate transcriptionally inflammasome responses. Finally, anti-inflammatory signals (e.g., IL-10) counterbalance inflammasome genes induction to limit deleterious inflammation. Transcriptional regulations thus appear as the first line of inflammasome regulation to raise the defense level in front of stress and infections but also to limit excessive or chronic inflammation.

Highlights

  • A common theme in inflammatory signaling pathways is their tight control

  • The involvement of Signal Transducer and Activator of Transcription 1 (STAT1) and IRF9 suggests that IFN-stimulated gene factor 3 (ISGF3), a ternary protein complex made of IRF9, STAT1, and STAT2 and functioning as a transcription factor downstream of type I IFN receptors, is a direct regulator of Il18 expression (Figure 4B) [111]

  • PU.1 and CCAAT/enhancer binding protein β (C/EBPβ) act in collaboration to generate a highly accessible IL1B promoter, yet without polymerase II (Pol II) binding at steady state [119]

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Summary

Introduction

The timely detection of pathogens and an appropriate magnitude of response are often dependent on the upregulation of specific sensors and/or their downstream adaptors/effectors. We will focus on the first line of inflammasomes regulation: the transcriptional regulation. Post-transcriptional regulations of inflammasome components have been reviewed recently [2,3,4,5,6]. The roles of noncoding RNAs (which include microRNAs (miRNA) and long noncoding RNAs (lncRNA)) will not be described since miRNAs affect mRNA stability and translation rate downstream of transcription and since inflammasome regulation by lncRNA is either indirect [7] or mediated by a direct action onto inflammasome proteins [8]. Inflammasome regulation differs between humans and mice; we will present the regulations occurring in these two species. All uppercase letters are used for human GENES symbols and capitalized words for murine Genes symbols

Overview of Inflammasome Complexes
Overview of Transcription Regulation
Transcriptional Regulation of Inflammasome Sensors
NAIP and NLRC4
Transcriptional Regulation of ASC
Caspase-1
Caspase-4
Caspase-11
Caspase-5
Transcriptional Regulation of Downstream Targets
IL-18 and IL-18BP
IL-1b and IL-1RA
Metabolic Regulation of IL1b
Negative Regulation of IL1b
IL1b Regulation in T Cells
IL1b Regulation in DCs
Conclusions
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