Transcriptional up-regulation of inhibitory PAS domain protein gene expression by hypoxia-inducible factor 1 (HIF-1): a negative feedback regulatory circuit in HIF-1-mediated signaling in hypoxic cells.
The inhibitory PAS (Per/Arnt/Sim) domain protein (IPAS), a dominant negative regulator of hypoxia-inducible transcription factors (HIFs), is potentially implicated in negative regulation of angiogenesis in such tissues as the avascular cornea of the eye. We have previously shown IPAS mRNA expression is up-regulated in hypoxic tissues, which at least in part involves hypoxia-dependent alternative splicing of the transcripts from the IPAS/HIF-3alpha locus. In the present study, we demonstrate that a hypoxia-driven transcriptional mechanism also plays a role in augmentation of IPAS gene expression. Isolation and analyses of the promoter region flanking to the first exon of IPAS gene revealed a functional hypoxia response element at position -834 to -799, whereas the sequence upstream of the HIF-3alpha first exon scarcely responded to hypoxic stimuli. A transient transfection experiment demonstrated that HIF-1alpha mediates IPAS promoter activation via the functional hypoxia response element under hypoxic conditions and that a constitutively active form of HIF-1alpha is sufficient for induction of the promoter in normoxic cells. Moreover, chromatin immunoprecipitation and electrophoretic mobility shift assays showed binding of the HIF-1 complex to the element in a hypoxia-dependent manner. Taken together, HIF-1 directly up-regulates IPAS gene expression through a mechanism distinct from RNA splicing, providing a further level of negative feedback gene regulation in adaptive responses to hypoxic/ischemic conditions.
Makino
Yuichi
Y
Division of Clinical Immunology, Advanced Clinical Research Center, Institute of Medical Science, University of Tokyo, 4-6-1, Shirokanedai, Tokyo, Japan. makino@asahikawa-med.ac.jp
Uenishi
Rie
R
Okamoto
Kensaku
K
Isoe
Tsubasa
T
Hosono
Osamu
O
Tanaka
Hirotoshi
H
Kanopka
Arvydas
A
Poellinger
Lorenz
L
Haneda
Masakazu
M
Morimoto
Chikao
C
D000818:Animals; D051017:Apoptosis Regulatory Proteins; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator / Q000378:metabolism; D001483:Base Sequence; D001921:Brain / Q000378:metabolism; D015687:Cell Hypoxia; D047369:Chromatin Immunoprecipitation; D024202:Electrophoretic Mobility Shift Assay; D042783:Endothelial Cells / Q000378:metabolism; D025461:Feedback, Physiological / Q000235:genetics*; D000860:Hypoxia / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins; D020218:Response Elements; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017384:Sequence Deletion; D012689:Sequence Homology, Nucleic Acid; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic; D015854:Up-Regulation / Q000502:physiology*
D051017:Apoptosis Regulatory Proteins; C497397:Arnt protein, mouse; C444643:Hif3a protein, mouse; D012333:RNA, Messenger; D012097:Repressor Proteins; D014157:Transcription Factors; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator