title: Endotoxin activates de novo sphingolipid biosynthesis via nuclear factor kappa B-mediated upregulation of Sptlc2.
abstract: Sphingolipids are membrane components and are involved in cell proliferation, apoptosis and metabolic regulation. In this study we investigated whether de novo sphingolipid biosynthesis in macrophages is regulated by inflammatory stimuli. Lipopolysaccharide (LPS) treatment upregulated Sptlc2, a subunit of serine palmitoyltransferase (SPT), mRNA and protein in Raw264.7 and mouse peritoneal macrophages, but Sptlc1, another subunit of SPT, was not altered. SPT activation by LPS elevated cellular levels of ceramides and sphingomyelin (SM). Pharmacological inhibition of nuclear factor kappa B (NFκB) prevented LPS-induced upregulation of Sptlc2 while transfection of p65 subunit of NFκB upregulated Sptlc2 and increased cellular ceramide levels. In contrast, MAP kinases were not involved in regulation of sphingolipid biosynthesis. Analysis of Sptlc2 promoter and chromatin immunoprecipitation (ChIP) assay showed that NFκB binding sites are located in Sptlc2 promoter region. Our results demonstrate that inflammatory stimuli activate de novo sphingolipid biosynthesis via NFκB and may play a critical role in lipid metabolism in macrophages.
authors.affiliation: Lee Gil Ya Cancer and Diabetes Institute, Department of Molecular Medicine, Gachon University of Medicine and Science, Inchon, South Korea.
authors.forename: Zhi-Qiang
authors.initials: ZQ
authors.lastname: Chang
authors.forename: Su-Yeon
authors.initials: SY
authors.lastname: Lee
authors.forename: Hye-Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jung Ran
authors.initials: JR
authors.lastname: Kim
authors.forename: Su-Jung
authors.initials: SJ
authors.lastname: Kim
authors.forename: In-Kyung
authors.initials: IK
authors.lastname: Hong
authors.forename: Byung-Chul
authors.initials: BC
authors.lastname: Oh
authors.forename: Cheol-Soo
authors.initials: CS
authors.lastname: Choi
authors.forename: Ira J
authors.initials: IJ
authors.lastname: Goldberg
authors.forename: Tae-Sik
authors.initials: TS
authors.lastname: Park
mesh_terms: D000818:Animals; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D051102:Serine C-Palmitoyltransferase / Q000235:genetics* / Q000378:metabolism; D013107:Sphingolipids / Q000096:biosynthesis*; D013109:Sphingomyelins / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D015854:Up-Regulation
chemical_list: D008070:Lipopolysaccharides; D016328:NF-kappa B; D012333:RNA, Messenger; D013107:Sphingolipids; D013109:Sphingomyelins; D051102:Serine C-Palmitoyltransferase; C495090:Sptlc2 protein, mouse