The histone methyltransferase Ezh2 restrains macrophage inflammatory responses

From Wiley via Jisc Publications RouterHistory: received 2021-02-16, rev-recd 2021-07-06, accepted 2021-07-23, pub-electronic 2021-08-31, pub-print 2021-10Article version: VoRPublication status: PublishedFunder: Medical Research Council Canada (MRC); Id: http://dx.doi.org/10.13039/501100007155; Grant(s): MR/N002024/1Funder: RCUK | Medical Research Council (MRC); Id: http://dx.doi.org/10.13039/501100000265; Grant(s): MRNO2995X/1Funder: Wellcome Trust (Wellcome); Id: http://dx.doi.org/10.13039/100010269; Grant(s): 107849/Z/15/Z, 107851/Z/15/ZFunder: RCUK | Biotechnology and Biological Sciences Research Council (BBSRC); Id: http://dx.doi.org/10.13039/501100000268; Grant(s): BB/L000954/1, BB/K003097/1Abstract: Robust inflammatory responses are critical to survival following respiratory infection, with current attention focused on the clinical consequences of the Coronavirus pandemic. Epigenetic factors are increasingly recognized as important determinants of immune responses, and EZH2 is a prominent target due to the availability of highly specific and efficacious antagonists. However, very little is known about the role of EZH2 in the myeloid lineage. Here, we show EZH2 acts in macrophages to limit inflammatory responses to activation, and in neutrophils for chemotaxis. Selective genetic deletion in macrophages results in a remarkable gain in protection from infection with the prevalent lung pathogen, pneumococcus. In contrast, neutrophils lacking EZH2 showed impaired mobility in response to chemotactic signals, and resulted in increased susceptibility to pneumococcus. In summary, EZH2 shows complex, and divergent roles in different myeloid lineages, likely contributing to the earlier conflicting reports. Compounds targeting EZH2 are likely to impair mucosal immunity; however, they may prove useful for conditions driven by pulmonary neutrophil influx, such as adult respiratory distress syndrome

Adipocyte NR1D1 dictates adipose tissue expansion during obesity

From eLife via Jisc Publications RouterHistory: received 2020-09-22, collection 2021, accepted 2021-07-30, pub-electronic 2021-08-05Publication status: PublishedFunder: Biotechnology and Biological Sciences Research Council; FundRef: http://dx.doi.org/10.13039/501100000268; Grant(s): BB/I018654/1Funder: Medical Research Council; FundRef: http://dx.doi.org/10.13039/501100000265; Grant(s): MR/N021479/1Funder: Medical Research Council; FundRef: http://dx.doi.org/10.13039/501100000265; Grant(s): MR/P00279X/1Funder: Medical Research Council; FundRef: http://dx.doi.org/10.13039/501100000265; Grant(s): MR/P011853/1Funder: Medical Research Council; FundRef: http://dx.doi.org/10.13039/501100000265; Grant(s): MR/P023576/1Funder: Wellcome Trust; FundRef: http://dx.doi.org/10.13039/100004440; Grant(s): 107849/Z/15/ZFunder: Wellcome Trust; FundRef: http://dx.doi.org/10.13039/100004440; Grant(s): 107851/Z/15/ZThe circadian clock component NR1D1 (REVERBα) is considered a dominant regulator of lipid metabolism, with global Nr1d1 deletion driving dysregulation of white adipose tissue (WAT) lipogenesis and obesity. However, a similar phenotype is not observed under adipocyte-selective deletion (Nr1d1Flox2-6:AdipoqCre), and transcriptional profiling demonstrates that, under basal conditions, direct targets of NR1D1 regulation are limited, and include the circadian clock and collagen dynamics. Under high-fat diet (HFD) feeding, Nr1d1Flox2-6:AdipoqCre mice do manifest profound obesity, yet without the accompanying WAT inflammation and fibrosis exhibited by controls. Integration of the WAT NR1D1 cistrome with differential gene expression reveals broad control of metabolic processes by NR1D1 which is unmasked in the obese state. Adipocyte NR1D1 does not drive an anticipatory daily rhythm in WAT lipogenesis, but rather modulates WAT activity in response to alterations in metabolic state. Importantly, NR1D1 action in adipocytes is critical to the development of obesity-related WAT pathology and insulin resistance

The cis-regulatory module interactome of vertebrate myoD1

Cis,regulatory modules (CRMs) are the functional DNA elements that encode the spatial and temporal expression patterns of a gene. Each gene is regulated by multiple CRMs, which may be hundreds of kilobases distant from the promoter. Many vertebrate CRMs have been characterised in isolation, but how CRMs act together to regulate complex patterns of expression is relatively unknown. Two CRMs that regulate expression of the muscle, specifying master gene myoD1 have previously been identified. Three additional potential CRMs were identified using a comparative genomics approach.The regulatory roles of these CRMs were investigated alone and in combination. Reporter plasmids containing all thirty,two possible combinations of these CRMs were made,and their expression was assayed in an immunologically,defined subpopulation of transfected mouse myoblast cells by flow cytometry. A statistical mechanics,based model used this exhaustive expression dataset to parameterise the interactions between the CRMs. This identified the ability of particular regulatory modules to have both enhancing and repressive effects upon transcription, dependent upon their surrounding CRM ‘context’. The physical proximity of the regulatory modules and myoD1 promoter in native chromatin during gene expression was confirmed by chromosome conformation capture analysis. To characterise the molecular basis of these properties further, a phylogenetic sequence comparison method was used to identify conserved transcription factor binding sites (TFBSs)within each CRM. A combination of experimental, bioinformatic and literature,derived evidence was used to prioritise binding sites fora large scale mutagenesis study to disentangle the molecular interactions between a prominent CRM pair. This allowed the mechanistic underpinnings of context sensitivity in this particular system to be identified

Overexpression of IκB⍺ modulates NF-κB activation of inflammatory target gene expression

Cells respond to inflammatory stimuli such as cytokines by activation of the nuclear factor-κB (NF-κB) signalling pathway, resulting in oscillatory translocation of the transcription factor p65 between nucleus and cytoplasm in some cell types. We investigate the relationship between p65 and inhibitor-κB⍺ (IκBα) protein levels and dynamic properties of the system, and how this interaction impacts on the expression of key inflammatory genes. Using bacterial artificial chromosomes, we developed new cell models of IκB⍺-eGFP protein overexpression in a pseudo-native genomic context. We find that cells with high levels of the negative regulator IκBα remain responsive to inflammatory stimuli and maintain dynamics for both p65 and IκBα. In contrast, canonical target gene expression is dramatically reduced by overexpression of IκBα, but can be partially rescued by overexpression of p65. Treatment with leptomycin B to promote nuclear accumulation of IκB⍺ also suppresses canonical target gene expression, suggesting a mechanism in which nuclear IκB⍺ accumulation prevents productive p65 interaction with promoter binding sites. This causes reduced target promoter binding and gene transcription, which we validate by chromatin immunoprecipitation and in primary cells. Overall, we show how inflammatory gene transcription is modulated by the expression levels of both IκB⍺ and p65. This results in an anti-inflammatory effect on transcription, demonstrating a broad mechanism to modulate the strength of inflammatory response

Identification of diurnal rhythmic blood markers in bronchial asthma

Rationale Asthma is a rhythmic inflammatory disease of the airway, regulated by the circadian clock. “Spill-over” of airway inflammation into the systemic circulation occurs in asthma and is reflected in circulating immune cell repertoire. The objective of the present study was to determine how asthma impacts peripheral blood diurnal rhythmicity. Methods 10 healthy and 10 mild/moderate asthma participants were recruited to an overnight study. Blood was drawn every 6 h for 24 h. Main results The molecular clock in blood cells in asthma is altered; PER3 is significantly more rhythmic in asthma compared to healthy controls. Blood immune cell numbers oscillate throughout the day, in health and asthma. Peripheral blood mononucleocytes from asthma patients show significantly enhanced responses to immune stimulation and steroid suppression at 16:00 h, compared to at 04:00 h. Serum ceramides show complex changes in asthma: some losing and others gaining rhythmicity. Conclusions This is the first report showing that asthma is associated with a gain in peripheral blood molecular clock rhythmicity. Whether the blood clock is responding to rhythmic signals received from the lung or driving rhythmic pathology within the lung itself is not clear. Dynamic changes occur in serum ceramides in asthma, probably reflecting systemic inflammatory action. The enhanced responses of asthma blood immune cells to glucocorticoid at 16:00 h may explain why steroid administration is more effective at this time