title: Lipopolysaccharide induces hypoxia-inducible factor-1 alpha mRNA expression and activation via NADPH oxidase and Sp1-dependent pathway in BV2 murine microglial cells.
abstract: Hypoxia-inducible factor-1 (HIF-1), the key transcription factor of hypoxia-inducible genes, is known to be involved in inflammation and immune response, but little is known about the regulation of HIF-1 during microglial activation. Thus, we examined effect of lipopolysaccharide (LPS) on HIF-1 activation and its signaling mechanism in BV2 microglial cells. LPS induced HIF-1alpha mRNA and protein expression as well as HIF-1 transcriptional activation. Moreover, HIF-1alpha knockdown by small interfering RNA (siRNA) decreased LPS-induced expression of hypoxia responsive genes, VEGF, iNOS, and COX-2. We then showed that LPS-induced HIF-1alpha mRNA expression was blocked by an antioxidant, NADPH oxidase inhibitors, and siRNA of gp91phox, a subunit of NADPH oxidase. In addition, we showed that specific pharmacological inhibitors of PI 3-kinase and protein kinase C decreased LPS-induced HIF-1alpha mRNA expression. Finally, we showed that inhibition of transcription factor Sp1 by mithramycin A or Sp1 siRNA decreased LPS-induced HIF-1alpha mRNA and protein expression. Consistently, LPS increased Sp1 DNA binding and its transcriptional activity. Taken together, these results suggest that LPS induces HIF-1alpha mRNA expression and activation via NADPH oxidase and Sp1 in BV2 microglia.
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Medicine, Kyung Hee University, Seoul 130-701, Republic of Korea.
authors.forename: Young Taek
authors.initials: YT
authors.lastname: Oh
authors.forename: Jung Yeon
authors.initials: JY
authors.lastname: Lee
authors.forename: Hana
authors.initials: H
authors.lastname: Yoon
authors.forename: Eunjoo H
authors.initials: EH
authors.lastname: Lee
authors.forename: Hyung Hwan
authors.initials: HH
authors.lastname: Baik
authors.forename: Sung Soo
authors.initials: SS
authors.lastname: Kim
authors.forename: Joohun
authors.initials: J
authors.lastname: Ha
authors.forename: Kyung-Sik
authors.initials: KS
authors.lastname: Yoon
authors.forename: Wonchae
authors.initials: W
authors.lastname: Choe
authors.forename: Insug
authors.initials: I
authors.lastname: Kang
mesh_terms: D000818:Animals; D002461:Cell Line, Transformed; D005786:Gene Expression Regulation / Q000187:drug effects*; D000860:Hypoxia / Q000378:metabolism / Q000473:pathology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics* / Q000378:metabolism; D007136:Immunoglobulins / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D051379:Mice; D017628:Microglia / Q000187:drug effects* / Q000378:metabolism; D019255:NADPH Oxidases / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D013997:Time Factors
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007136:Immunoglobulins; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C090698:SP1 antigen; D019255:NADPH Oxidases