Oxygen-regulated expression of TGF-beta 3, a growth factor involved in trophoblast differentiation.
The transforming growth factor-beta 3 (TGF-beta 3) is involved in oxygen-dependent differentiation processes during placental development and pregnancy disorders. However, the importance of oxygen partial pressure for the regulation of TGF-beta 3 expression is presently unclear. We and others presented preliminary evidence that the hypoxia-inducible factor-1 (HIF-1) confers TGF-beta 3 transcription but it was unknown whether this occurred directly or indirectly. To analyze how HIF-1 regulates TGF-beta 3 gene transcription, we cloned and sequenced the mouse TGF-beta 3 promoter region. Multiple putative HIF-1 binding sites (HBSs) were identified, many of which co-localized with two G+C rich CpG islands 5' to the TGF-beta 3 transcription start site. A 6.8 kb fragment of the TGF-beta 3 promoter induced reporter gene expression under hypoxic conditions or when treated with an iron chelator known to stabilize and activate the HIF-1 alpha subunit. Deletion of a 2.4 kb fragment upstream of the distal CpG island abolished inducibility of reporter gene expression. Two HBSs (HBS1 and HBS6) that bound the HIF-1 protein could be identified within this 2.4 kb fragment. These results suggest that TGF-beta 3 gene expression is directly regulated by HIF-1.
Department of Obstetrics and Perinatal Physiology, University Hospital Zürich, Zürich, Switzerland.
L
L
Schäffer
A
A
Scheid
P
P
Spielmann
C
C
Breymann
R
R
Zimmermann
M
M
Meuli
M
M
Gassmann
H H
HH
Marti
R H
RH
Wenger
D000818:Animals; D001665:Binding Sites; D002454:Cell Differentiation; D015687:Cell Hypoxia; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D051379:Mice; D009687:Nuclear Proteins / Q000502:physiology*; D011247:Pregnancy; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D014157:Transcription Factors; D015533:Transcriptional Activation; D016212:Transforming Growth Factor beta / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D053782:Transforming Growth Factor beta3; D014327:Trophoblasts / Q000166:cytology
D004268:DNA-Binding Proteins; C497443:Hif1a protein, mouse; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009687:Nuclear Proteins; D012333:RNA, Messenger; C509045:Tgfb3 protein, mouse; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D053782:Transforming Growth Factor beta3; D004247:DNA