The methylation status of the chemerin promoter region located from − 252 to + 258 bp regulates constitutive but not acute-phase cytokine-inducible chemerin expression levels

Abstract

Chemerin is a chemoattractant protein with adipokine properties encoded by the retinoic acid receptor responder 2 (RARRES2) gene. it has gained more attention in the past few years due to its multilevel impact on metabolism and immune responses. However, mechanisms controlling the constitutive and regulated expression of RARRES2 in a variety of cell types remain obscure. To our knowledge, this report is the first to show that DNA methylation plays an important role in the cell-specific expression of RARRES2 in adipocytes, hepatocytes, and B lymphocytes. Using luciferase reporter assays, we determined the proximal fragment of the RARRES2 gene promoter, located from − 252 to + 258 bp, to be a key regulator of transcription. Moreover, we showed that chemerin expression is regulated in murine adipocytes by acute-phase cytokines, interleukin 1β and oncostatin M. in contrast with adipocytes, these cytokines exerted a weak, if any, response in mouse hepatocytes, suggesting that the effects of IL-1β and OSM on chemerin expression is specific to fat tissue. Together, our findings highlight previously uncharacterized mediators and mechanisms that control chemerin expression. Chemerin is a small (18 kDa) multifunctional protein capable of regulating different biological processes, including immune cell migration, adipogenesis, osteoblastogenesis, angiogenesis, myogenesis, and glucose homeostasis 1. Moreover, it shows broad-spectrum antimicrobial activity in both human and mouse epidermis, suggesting it plays a role in maintaining skin-barrier homeostasis 2,3. Chemerin-induced signaling is mediated predominantly through chemokine-like receptor 1 (CMKLR1), which is expressed by many cells including plasmacytoid dendritic cells (pDCs), macrophages, natural killer (NK) cells, adipocytes, hepatocytes, and keratinocytes 2,4-9. Chemerin is secreted as pro-chemerin and circulates in plasma as an inactive precursor protein (Chem163S) that can subsequently be activated through posttranslational carboxyl-terminal processing by a variety of proteinases 10,11. The gene encoding chemerin is known as retinoic acid receptor responder 2 (RARRES2) 12 , or as tazaroteneinduced gene 2 (TIG2) given it was first discovered in tazarotene-treated psoriatic skin lesions 13,14. Liver and adipose tissue are reported to be the major sites of chemerin production; nonetheless, RARRES2 mRNA is detectable in many other tissues, including the adrenal glands, ovaries, pancreas, lungs, kidney, and skin 2,15. Chemerin

Chemerin Is Induced in Non-Alcoholic Fatty Liver Disease and Hepatitis B-Related Hepatocellular Carcinoma

“…Aberrant promoter methylation is a hallmark of cancer, and was demonstrated to control constitutive chemerin expression in hepatocytes [32]. Maternal smoking during pregnancy was associated with reduced chemerin promoter methylation in the skin and induced gene expression [33].…”

Identification, Characterization, and Tissue Expression Pattern of Alternatively Spliced Transcript Variants of Mouse RARRES2 Gene

“…10,27,34−36 Chemerin expression is regulated by a variety of in ammatory and metabolic mediators in a manner dependent on cell type. 25,37 We previously showed that IL-1β and OSM upregulated chemerin expression in human skin cultures 7 , and mouse adipocytes 25 . Moreover, bacteria, like S. aureus, upregulate chemerin levels in models of human epidermis and mouse skin.…”

“…We have shown previously that acute-phase cytokines, interleukin 1b (IL-1β) and oncostatin M (OSM), regulate chemerin expression in mouse adipocytes and human 3D skin cultures. 7,25 Therefore, we next analyzed if these cytokines can affect the balance between newly discovered RARRES2 transcript variant 4 and others splice variants in mouse tissues. The transcript ratio remained stable in all investigated mouse tissues, and there were no statistically signi cant differences between PBS and cytokine treated animals (Fig.…”

“…IL-1β and OSM were injected intraperitoneally at doses of 10 μg/kg BW and 160 μg/kg BW, respectively as previously described. 25 After 48 h, different tissues were isolated and subjected to RT-QPCR analysis. All experimental procedures were approved by the First Local Ethical Committee on Animal Testing at the Jagiellonian University in Krakow, Poland (permit no.…”

“…Expression stabilities of commonly used reference genes were analyzed as described previously. 25 Relative gene expression normalized to the geometric mean of these housekeeping genes was calculated using the 2 −ΔΔCT method. 40 Relative Incidence of Variant (RIV) was obtained with the method described by Londoño et al 24 , PCR e ciencies of primer sets were calculated with CFX Maestro Software (Bio-Rad) using pcDNA3.1 plasmids encoding mChem162K and mChem153K as a template Alternative splicing analyses from RNA-Seq datasets Information about RARRES2 expression level in distinct tissues and cell lines as well as isoform quanti cation were acquired from VastDB.…”