Transcriptional activation of urokinase by the Krüppel-like factor Zf9/COPEB activates latent TGF-beta1 in vascular endothelial cells.
Understanding the regulation of genes controlling fibrinolysis and matrix homeostasis is essential for elucidating the basis of tissue repair. A recently described novel Krüppel-like factor, Zf9, is up-regulated in acute liver injury in activated hepatic stellate cells. Because Zf9 can be induced widely, its activity was examined in vascular endothelium, a key cell in vascular injury. Zf9 is induced as an immediate-early response gene in bovine aortic endothelial cells (BAECs) following treatment with serum or phorbol ester. Zf9 transcriptionally activates urokinase plasminogen activator (uPA). Recombinant Zf9-GST binds to wild-type but not mutated 'GC-box' motifs within the human uPA promoter (-63 to -32), with greatest affinity to the middle of 3 contiguous GC boxes. Transient transfection of Zf9 drives transactivation of a full-length uPA promoter- and GC box-construct, but not a uPA promoter-construct devoid of GC boxes. Transactivation of uPA by Zf9 is also supported in Drosophila S2 cells. Most importantly, transiently transfected Zf9 up-regulates endogenous uPA messenger RNA and activity in BAECs, resulting in increased bioactive transforming growth factor-beta (TGF-beta) via enhancement of proteolytic activation of the latent molecule. Furthermore, concomitant expression of Zf9 and uPA proteins was observed in arterial endothelial cells after balloon injury in rats, suggesting a potential role of Zf9 in uPA expression not only in vitro but also in vivo. These findings suggest a role of Zf9 in the injury response by enhancing uPA synthesis and subsequent activation of latent TGF-beta. (Blood. 2000;95:1309-1316)
Kojima
S
S
Laboratory of Molecular Cell Sciences, Tsukuba Life Science Center, The Institute of Physical and Chemical Research (RIKEN), Koyadai, Tsukuba, Ibaraki 305-0074, Japan. kojima@rtc.riken.go.jp
Hayashi
S
S
Shimokado
K
K
Suzuki
Y
Y
Shimada
J
J
Crippa
M P
MP
Friedman
S L
SL
D000818:Animals; D001011:Aorta; D001483:Base Sequence; D001665:Binding Sites; D002339:Carotid Arteries / Q000378:metabolism / Q000473:pathology; D020212:Carotid Artery Injuries / Q000378:metabolism / Q000473:pathology; D002417:Cattle; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004331:Drosophila melanogaster; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D005341:Fibrinolysin / Q000378:metabolism; D005786:Gene Expression Regulation; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D000075723:Kruppel-Like Factor 6; D051741:Kruppel-Like Transcription Factors; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000235:genetics*; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics*
C105465:KLF6 protein, human; C491357:Klf6 protein, rat; D000075723:Kruppel-Like Factor 6; D051741:Kruppel-Like Transcription Factors; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator