Lipopolysaccharide induces hypoxia-inducible factor-1 alpha mRNA expression and activation via NADPH oxidase and Sp1-dependent pathway in BV2 murine microglial cells.
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.
Oh
Young Taek
YT
Department of Biochemistry and Molecular Biology, School of Medicine, Kyung Hee University, Seoul 130-701, Republic of Korea.
Lee
Jung Yeon
JY
Yoon
Hana
H
Lee
Eunjoo H
EH
Baik
Hyung Hwan
HH
Kim
Sung Soo
SS
Ha
Joohun
J
Yoon
Kyung-Sik
KS
Choe
Wonchae
W
Kang
Insug
I
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
D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007136:Immunoglobulins; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C090698:SP1 antigen; D019255:NADPH Oxidases