Vitamin D Receptor Gene Expression in Adipose Tissue of Obese Individuals is Regulated by miRNA and Correlates with the Pro-Inflammatory Cytokine Level.

Wojciech Lisik,Zbigniew Bartoszewicz,Krzysztof Kozniewski,Maurycy Jonas,Monika Puzianowska-Kuznicka,Marta Izabela Jonas,Alina Kuryłowicz

doi:10.3390/ijms20215272

Abstract

Background: Given the role that vitamin D (VD) plays in the regulation of the inflammatory activity of adipocytes, we aimed to assess whether obesity changes the expression of VD-related genes in adipose tissue and, if so, to investigate whether this phenomenon depends on microRNA interference and how it may influence the local inflammatory milieu. Methods: The expression of genes encoding VD 1α-hydroxylase (CYP27B1), 24-hydroxylase (CYP24A1) and receptor (VDR), selected interleukins and microRNAs was evaluated by real-time PCR in visceral (VAT) and in subcutaneous (SAT) adipose tissues of 55 obese (BMI > 40 kg/m2) and 31 normal-weight (BMI 20–24.9 kg/m2) individuals. Results: VDR mRNA levels were higher, while CYP27B1 levels were lower in adipose tissues of obese patients than in those of normal-weight controls (VAT: P = 0.04, SAT: P < 0.0001 and VAT: P = 0.004, SAT: P = 0.016, respectively). The expression of VDR in VAT of obese subjects correlated negatively with levels of miR-125a-5p (P = 0.0006, rs = −0.525), miR-125b-5p (P = 0.001, rs = −0.495), and miR-214-3p (P = 0.009, rs = −0.379). Additionally, VDR mRNA concentrations in visceral adipose tissues of obese subjects correlated positively with mRNA levels of interleukins: 1β, 6 and 8. Conclusions: We observed obesity-associated up-regulation of VDR and down-regulation of CYP27B mRNA levels in adipose tissue. VDR expression correlates with the expression of pro-inflammatory cytokines and may be regulated by miRNAs.

Highlights

The discovery of vitamin D receptor (VDR) and its identification in a wide panel of tissues broadened our understanding about the role of vitamin D3 in the maintenance of body homeostasis
We aimed to evaluate if obesity influences the expression of genes crucial for VD activation (CYP27B1), inactivation (CYP24A1) and action (VDR) in different adipose tissues depots
We aimed to evaluate if obesity influences the expression of genes crucial for VD activation (CYP27B1), inactFivigautiroen1.(CYAP2si4mAp1l)ifiaenddsachcteimoneaminindiDffemreentatbaodliispmo.se Ctihssouleecsaldciefperootls.(fNoremxte,dwuenidnevretshtiegated if VDinsfltuaetuncseaonfdumltriaRvNioAletin(UteVrf)erraeynsceincothueldskpinlaoyrasuroplpeliiend tbhyistphehednieotm) uenndoenr.gFoiensahllyyd, rboyxycloatriroenlating the matRpNosAitiloenv2e5lsinofthtehelisveerg, eanndesthwenithinmthReNreAactlieovneclastoalfytshede bpyro1-αin-hfyladmromxyaltaosrey(CcYyPto2k7Bin1e),st,hwe eacatiivmeed to assesmsethaboowliteo—b1e,2s5it-yd-irheyldartoexdychcohlaencaglceisferionlaitsefdormgeedn.eHs ydexropxryelsastiioonnat mpoasyitioinm24p(accattaltyhseed local inflabmymviatatomriynmDi2li4e-uhyidnroaxdyiplaoses—e tCisYsPu2e4.A1) initiates the degradation of vitamin D metabolites

Summary

Introduction

The discovery of vitamin D receptor (VDR) and its identification in a wide panel of tissues broadened our understanding about the role of vitamin D3 (cholecalciferol, hereinafter referred to as vitamin D, VD) in the maintenance of body homeostasis. Using bioinformatics tools (TargetScanHuman available at http://www.targetscan.org, miRanda-mirSVR available at http://www.microrna.org/microrna/home.do and the Pictar available at http://pictar.mdc-berlin.de), results of the next-generation-sequencing screening [19] and based on the available literature covering in vitro studies, we selected miRNA that potentially interfere with VDR and CYP27B1 3 UTR sequences (Supplementary Table S1) We measured their concentrations in the investigated tissues in order to correlate them with VDR and CYP27B1 mRNA levels. In the case of all these miRNAs, we found significant differences in their expression between the investigated tissues results of the next-generation-sequencing screening [19] and based on the available literature covering in vitro studies, we selected miRNA that potentially interfere with VDR and CYP27B1 3′UTR sequences (Supplementary Table S1) CCoorrrreellaattiioonn bbeettwweeeenn mmRRNNAAlleevveellssooffVVDDRRaannddmmRRNNAAlelevveelslsoof fggenenesesenencocdodinignginitnetrelreluekuiknin (6IL(I6La6,ba),,bi)n, tienrtleerulkeuinki8n(I8L8(ILc,8d)c,adn)dainndteirnleteurkleinuk1βin(1ILβ1B(ILe1,fB) ien,fv)iisncevraislc(eVrAalT()VaAndT)suanbcdustaunbecouutasn(eSoAuTs) (aSdAipTo)saedtiipssousee otifssoubeesoef (oOb)eisned(iOv)idinudalisv.iduals

Discussion

Studied Groups and Tissues

Findings

Statistical Analysis