title: Differential regulation of HIF-3α in LPS-induced BV-2 microglial cells: Comparison and characterization with HIF-1α.
abstract: Hypoxia inducible factor(s) (HIF) are transcription factors that respond to a low level of oxygen or hypoxic conditions. The HIF pathway has been poorly studied under neuroinflammatory conditions, and no reports are available on the regulation of HIF-3α. Several studies have established that non-hypoxic stimuli can modulate the HIF pathway in a cell-specific manner. Recent reports suggest that hypoxia elicits inflammation or that inflammation during hypoxia is involved in a wide array of human diseases. In the present study, we used lipopolysaccharide (LPS), a well know inflammatory agent, to characterize the HIF-3α expression pattern and compare it with that of HIF-1α under inflammatory conditions in BV-2 microglial cells. Moreover, we used reactive oxygen species inhibitors (rotenone, diphenyleneiodonium, and N-acetyl-L-cysteine) under inflammatory conditions to determine the role of the functional electron transport chain in the regulation of HIF-3α in BV-2 microglial cells. Additionally, we utilized YC-1, a specific inhibitor of HIF-1α, to determine the role of HIF-3α in inflammatory conditions after inhibiting the HIF-1α pathway. YC-1 inhibited nuclear localization of HIF-1α following treatment with LPS in BV-2 microglia cells. Immunoblot and immunocytochemistry revealed a transient effect on HIF-3α after pre-treating the cells with YC-1. Furthermore, we determined the role of nuclear factor kappa B (NF-κB) in the regulation of HIF-3α using the NF-κB inhibitor PDTC in LPS-stimulated BV-2 microglia cells. PDTC altogether abolished LPS-induced nuclear translocation of HIF-3α with a partial effect on HIF-1α, suggesting that HIF-3α expression under inflammatory conditions may be directly under the control of the NF-κB pathway in BV-2 microglial cells. Interestingly, HIF-3α and HIF-1α exhibited almost similar responses to a variety of activating or inhibiting pharmacological agents. These results provide the first evidence for regulation of HIF-3α under inflammatory conditions in BV-2 microglial cells.
authors.affiliation: (a)Department of Biotechnology, Konkuk University, Chungju-si 380-701, Republic of Korea.
authors.forename: Hemant
authors.initials: H
authors.lastname: Kumar
authors.affiliation: Department of Biomedical chemistry, Konkuk University, Chungju-si 380-701, Republic of Korea.
authors.forename: Ji-Hong
authors.initials: JH
authors.lastname: Lim
authors.affiliation: (a)Department of Biotechnology, Konkuk University, Chungju-si 380-701, Republic of Korea.
authors.forename: In-Su
authors.initials: IS
authors.lastname: Kim
authors.affiliation: (a)Department of Biotechnology, Konkuk University, Chungju-si 380-701, Republic of Korea. Electronic address: choidk@kku.ac.kr.
authors.forename: Dong-Kug
authors.initials: DK
authors.lastname: Choi
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000502:physiology; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D002460:Cell Line; D051547:Heme Oxygenase-1 / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007249:Inflammation / Q000188:drug therapy / Q000378:metabolism; D008070:Lipopolysaccharides / Q000633:toxicity*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D017628:Microglia / Q000187:drug effects / Q000276:immunology*; D008928:Mitochondria / Q000187:drug effects / Q000276:immunology; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012097:Repressor Proteins; D015398:Signal Transduction / Q000187:drug effects; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology
chemical_list: D051017:Apoptosis Regulatory Proteins; C497443:Hif1a protein, mouse; C444643:Hif3a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D016328:NF-kappa B; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D012097:Repressor Proteins; D014157:Transcription Factors; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D051547:Heme Oxygenase-1; C496542:Hmox1 protein, mouse
keywords: BV-2 microglia cells; HIF-1α; HIF-3α; NFκB; YC-1