title: Cellular content of UDP-N-acetylhexosamines controls hyaluronan synthase 2 expression and correlates with O-linked N-acetylglucosamine modification of transcription factors YY1 and SP1.
abstract: Hyaluronan, a high molecular mass polysaccharide on the vertebrate cell surface and extracellular matrix, is produced at the plasma membrane by hyaluronan synthases using UDP-GlcNAc and UDP-GlcUA as substrates. The availability of these UDP-sugar substrates can limit the synthesis rate of hyaluronan. In this study, we show that the cellular level of UDP-HexNAc also controls hyaluronan synthesis by modulating the expression of HAS2 (hyaluronan synthase 2). Increasing UDP-HexNAc in HaCaT keratinocytes by adding glucosamine down-regulated HAS2 gene expression, whereas a decrease in UDP-HexNAc, realized by mannose treatment or siRNA for GFAT1 (glutamine:fructose-6-phosphate amidotransferase 1), enhanced expression of the gene. Tracing the UDP-HexNAc-initiated signal to the HAS2 promoter revealed no change in the binding of STAT3, NF-κB, and cAMP response element-binding protein, shown previously to mediate growth factor and cytokine signals on HAS2 expression. Instead, altered binding of SP1 and YY1 to the promoter correlated with cellular UDP-HexNAc content and inhibition of HAS2 expression. siRNA silencing of YY1 and SP1 confirmed their inhibitory effects on HAS2 expression. Reduced and increased levels of O-GlcNAc-modified SP1 and YY1 proteins were associated with stimulation or inhibition of HAS2 expression, respectively. Our data are consistent with the hypothesis that, by regulating the level of protein O-GlcNAc modifications, cellular UDP-HexNAc content controls HAS2 transcription and decreases the effects on hyaluronan synthesis that would result from cellular fluctuations of this substrate.
authors.affiliation: Institute of Biomedicine, University of Eastern Finland, FIN-70211 Kuopio, Finland.
authors.forename: Tiina A
authors.initials: TA
authors.lastname: Jokela
authors.forename: Katri M
authors.initials: KM
authors.lastname: Makkonen
authors.forename: Sanna
authors.initials: S
authors.lastname: Oikari
authors.forename: Riikka
authors.initials: R
authors.lastname: Kärnä
authors.forename: Elina
authors.initials: E
authors.lastname: Koli
authors.forename: Gerald W
authors.initials: GW
authors.lastname: Hart
authors.forename: Raija H
authors.initials: RH
authors.lastname: Tammi
authors.forename: Carsten
authors.initials: C
authors.lastname: Carlberg
authors.forename: Markku I
authors.initials: MI
authors.lastname: Tammi
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism* / Q000494:pharmacology; D019295:Computational Biology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects; D014453:Glucuronosyltransferase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D000076002:Hyaluronan Synthases; D006820:Hyaluronic Acid / Q000096:biosynthesis; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism; D008358:Mannose / Q000378:metabolism / Q000494:pharmacology; D019884:Nitrogenous Group Transferases / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D013997:Time Factors; D014530:Uridine Diphosphate / Q000378:metabolism*; D050986:YY1 Transcription Factor / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016329:Sp1 Transcription Factor; D050986:YY1 Transcription Factor; D014530:Uridine Diphosphate; D006820:Hyaluronic Acid; D014453:Glucuronosyltransferase; C101754:HAS2 protein, human; D000076002:Hyaluronan Synthases; D019884:Nitrogenous Group Transferases; D008358:Mannose; D000117:Acetylglucosamine