NFATc1 releases BCL6‐dependent repression of CCR2 agonist expression in peritoneal macrophages fromSaccharomyces cerevisiaeinfected mice

Abstract

The link between the extensive usage of calcineurin (CN) inhibitors cyclosporin A and tacrolimus (FK506) in transplantation medicine and the increasing rate of opportunistic infections within this segment of patients is alarming. Currently, how peritoneal infections are favored by these drugs, which impair the activity of several signaling pathways including the Ca ++ /CN/NFAT, Ca ++ /CN/cofilin, Ca ++ /CN/BAD, and NF-κB networks, is unknown. Here, we show that Saccharomyces cerevisiae infection of peritoneal resident macrophages triggers the transient nuclear translocation of NFATc1β isoforms, resulting in a coordinated, CN-dependent induction of the Ccl2, Ccl7, and Ccl12 genes, all encoding CCR2 agonists. CN inhibitors block the CCR2-dependent recruitment of inflammatory monocytes (IM) to the peritoneal cavities of S. cerevisiae infected mice. In myeloid cells, NFATc1/β proteins represent the most prominent NFATc1 isoforms. NFATc1/β ablation leads to a decrease of CCR2 chemokines, impaired mobilization of IMs, and delayed clearance of infection. We show that, upon binding to a composite NFAT/BCL6 regulatory element within the Ccl2 promoter, NFATc1/β proteins release the BCL6-dependent repression of Ccl2 gene in macrophages. These findings suggest a novel CN-dependent cross-talk between NFAT and BCL6 transcription factors, which may affect the outcome of opportunistic fungal infections in immunocompromised patients.Keywords: BCL6 r CCL2 r CCR2 r Inflammatory monocytes r NFATc1 r Opportunistic infection Additional supporting information may be found in the online version of this article at the publisher's web-site [4,5]. Although ablation of CN-B compromises neutrophil-dependent killing of fungal pathogens ex vivo [6], it is still not completely clear how CsA and FK506 facilitate fungal and other opportunistic infections. We will show here that in peritoneal macrophages CsA and FK506 inhibit the synthesis of chemokines that attract neutrophils and inflammatory monocytes (IMs) to the site of infection.Tissue-specific resident macrophages [7] are key components of the heterogeneous mononuclear phagocyte system, which is defined on the basis of common ontogeny and phagocytic activity [8]. The mononuclear phagocyte system provides the first line of innate immune responses against invading pathogens. In the peritoneal cavity, resident macrophages constitute the largest population of phagocytotic cells. However, the successful clearance of peritoneal infections critically depends on the rapid recruitment of neutrophils and IMs [9] from a specific shortlived CX 3 CR1 lo CCR2 + subset of peripheral blood monocytes [10].Peritoneal infections trigger the release of several CCR2-specific chemokines from peritoneal resident macrophages (prM ), such as CCL2, CCL7, and CCL13. However, significantly reduced numbers of recruited IMs and the inability to control toxoplasmosis in mice deficient for CCL2 or CCR2 suggest a critical nonredundant role for the CCR2/CCL2 axis in the clearance of peritoneal infections [11,12]. Aberrant...

Residue-Specific Message Encoding in CD40-Ligand

“…Because the signals through kinases converge on the transcription factors that carry the message to the nucleus for effecting gene transcription and effector functions ( Busch et al., 2016 ; Baccam et al., 2003 ; Liao et al., 2011 ; Roy et al., 2015 ; Severa et al., 2014 ; Suttles et al., 1999 ), we assessed the phosphorylation of key transcription factors in CD40 signaling. Peptides 7 and 8 showed the highest phosphorylation of IκBα, which upon phosphorylation relieves NF-κB to be activated by phosphorylation.…”

“…Both TRAF-dependent and -independent signaling activate these signaling intermediates. CD40 signaling leads to activation of both canonical and non-canonical NF-κB pathways and of other associated Transcription Factors (TFs) such as ATF2, ELK1, BLIMP-1, BATF, and NFAT initiating differential gene expression and the ensuing effector function ( Elgueta et al., 2009 ; Elgueta et al, 2010 ; Roy et al., 2015 ; Busch et al., 2016 ). CD40L-CD40 signaling is exploited by many pathogens for their survival; the switching of CD40 signaling to heighten the production of anti-inflammatory cytokines is a clear example ( Mathur et al., 2004 ).…”

The Transcription Factor NFATc1 Supports the Rejection of Heterotopic Heart Allografts

“…While Nfatc1 flx/flx x mb1-cre mice bear NFATc1-deficient B cells, Nfatc1 flx/flx x CD4-cre mice bear NFATc1-deficient CD4 + and CD8 + T cells. Nfatc1P2Δ mice carry an Nfatc1 P2 promoter deletion and, therefore, are deficient for P2-directed transcripts ( 23 ). The survival of heart function was monitored daily during the first 3 weeks after transplantation, then four times per week.…”

“…In such Nfatc1P2Δ mice, the generation of NFATc1/β isoforms was inhibited [see Figure S1 in Supplementary Material and Ref. ( 23 )]. Nfatc1P2Δ mice were born at expected Mendelian ratios, were viable and developmentally indistinguishable from their Nfatc1P2 flx/flx littermates, and their lymphoid compartments remained unaffected.…”

“…Nfatc1P2Δ mice carry an Nfatc1 P2 promoter deletion and, due to a CMV-promoter-driven cre are deficient for P2-directed transcripts [see Figure S1 in Supplementary Material and Ref. ( 23 )]. Bacterial artificial chromosome (BAC) transgenic (tg) mice expressing NFATc1/A-Bio protein [and BirA, the biotin-ligase from E. coli ( 24 )] have been described previously in Ref.…”