Project description:Macrophages play fundamental roles in regulation of inflammatory responses to pathogens, resolution of inflammation and tissue repair, and maintenance of tissue homeostasis. The long (L) and short (S) isoforms of SP-R210/MYO18A, a macrophage receptor for surfactant protein A (SP-A) and C1q, regulate basal and inflammatory macrophage phenotype at multiple gene expression, translational, and subcellular levels in addition to their SP-A and C1q-mediated functions; disruption of L renders macrophages hyper-inflammatory, although the underlying mechanism had previously been unexplored. We questioned whether disruption of the L isoform would alter the global genomic responses. RNA sequencing analysis of SP-R210L(DN) macrophages revealed basal and influenza induced upregulation of genes associated with inflammatory pathways, including TLR, RIG-I, NOD, and cytoplasmic DNA signaling, whereas knockdown of both SP-R210 isoforms (L and S) only resulted in increased RIG-I and NOD signaling. Chromatin immunoprecipitation sequencing (ChIP-seq) analysis showed increased genome-wide deposition of the pioneer transcription factor PU.1 in SP-R210L(DN) compared to WT cells. ChIP-seq analysis of histone H3 methylation showed alterations in both repressive (H3K9me3 and H3K27me3) and transcriptionally active (H3K9me3) histone marks. Influenza A virus (IAV) infection, which stimulates an array of cytosolic and TLR-mediated antiviral mechanisms, resulted in differential redistribution between proximal promoter and distal sites and decoupling of PU.1 binding from Toll-like receptor regulated gene promoters in SP-R210L(DN) cells. Our findings suggest that SP-R210L-deficient macrophages are poised with an open PU.1-primed chromatin conformation to rapidly respond to inflammatory and metabolic stimuli.
Project description:In humans there are two surfactant protein A (SP-A) functional genes SFTPA1 and SFTPA2 encoding innate immune molecules, SP-A1 and SP-A2, respectively, with numerous genetic variants each. SP-A interacts and regulates many of the functions of alveolar macrophages (AM). It is shown that SP-A variants differ in their ability to regulate the AM miRNome in response to oxidative stress (OxS). Because humans have both SP-A gene products, we were interested to determine the combined effect of co-expressed SP-A1/SP-A2 (co-ex) in response to ozone (O3) induced OxS on AM miRNome. Human transgenic (hTG) mice, carrying both SP-A1/SP-A2 (6A2/1A0, co-ex) and SP-A- KO were utilized. The hTG and KO mice were exposed to filtered air (FA) or O3 and miRNA levels were measured after AM isolation with or without normalization to KO. We found: (i) The AM miRNome of co-ex males and females in response to OxS to be largely downregulated after normalization to KO, but after Bonferroni multiple comparison analysis only in females the AM miRNome remained significantly different compared to control (FA); (ii) The targets of the significantly changed miRNAs were downregulated in females and upregulated in males; (iii) Several of the validated mRNA targets were involved in pro-inflammatory response, anti-apoptosis, cell cycle, cellular growth and proliferation; (iv) The AM of SP-A2 male, shown, previously to have major effect on the male AM miRNome in response to OxS, shared similarities with the co-ex, namely in pathways involved in the pro-inflammatory response and anti-apoptosis but also exhibited differences with the cell-cycle, growth, and proliferation pathway being involved in co-ex and ROS homeostasis in SP-A2 male. We speculate that the presence of both gene products versus single gene products differentially impact the AM responses in males and females in response to OxS.