TitleAn LXR-NCOA5 gene regulatory complex directs inflammatory crosstalk-dependent repression of macrophage cholesterol efflux.
Publication TypeJournal Article
Year of Publication2015
AuthorsGillespie, MA, Gold, ES, Ramsey, SA, Podolsky, I, Aderem, A, Ranish, JA
JournalEMBO J
Date Published2015 May 05
KeywordsAnimals, ATP Binding Cassette Transporter 1, Cholesterol, Female, Gene Expression Regulation, Inflammation, Liver X Receptors, Macrophages, Mass Spectrometry, Mice, Inbred C57BL, Mice, Knockout, Nuclear Receptor Coactivators, Orphan Nuclear Receptors, Promoter Regions, Genetic, RNA Polymerase II, Signal Transduction, Toll-Like Receptor 3

LXR-cofactor complexes activate the gene expression program responsible for cholesterol efflux in macrophages. Inflammation antagonizes this program, resulting in foam cell formation and atherosclerosis; however, the molecular mechanisms underlying this antagonism remain to be fully elucidated. We use promoter enrichment-quantitative mass spectrometry (PE-QMS) to characterize the composition of gene regulatory complexes assembled at the promoter of the lipid transporter Abca1 following downregulation of its expression. We identify a subset of proteins that show LXR ligand- and binding-dependent association with the Abca1 promoter and demonstrate they differentially control Abca1 expression. We determine that NCOA5 is linked to inflammatory Toll-like receptor (TLR) signaling and establish that NCOA5 functions as an LXR corepressor to attenuate Abca1 expression. Importantly, TLR3-LXR signal crosstalk promotes recruitment of NCOA5 to the Abca1 promoter together with loss of RNA polymerase II and reduced cholesterol efflux. Together, these data significantly expand our knowledge of regulatory inputs impinging on the Abca1 promoter and indicate a central role for NCOA5 in mediating crosstalk between pro-inflammatory and anti-inflammatory pathways that results in repression of macrophage cholesterol efflux.

Alternate JournalEMBO J
PubMed ID25755249
PubMed Central IDPMC4426483
Grant ListR01 AI032972 / AI / NIAID NIH HHS / United States
MFE-112984 / / Canadian Institutes of Health Research / Canada
U19 AI100627 / AI / NIAID NIH HHS / United States
2P50 GM076547 / GM / NIGMS NIH HHS / United States
P50 GM076547 / GM / NIGMS NIH HHS / United States
HL098807 / HL / NHLBI NIH HHS / United States
R01 AI025032 / AI / NIAID NIH HHS / United States
K25 HL098807 / HL / NHLBI NIH HHS / United States