Type I protein C deficiency caused by disruption of a hepatocyte nuclear factor (HNF)-6/HNF-1 binding site in the human protein C gene promoter.
Protein C is a vitamin K-dependent zymogen of a serine protease that inhibits blood coagulation by proteolytic inactivation of factors Va and VIIIa. Individuals affected by protein C deficiency are at risk for venous thrombosis. One such affected individual was shown earlier to carry a -14 T --> C mutation in the promoter region of the protein C gene. It is shown here that the region around this mutation corresponds to a binding site for the transcription factor hepatocyte nuclear factor (HNF)-6 and that this site completely overlaps an HNF-1 binding site. HNF-6 and HNF-1 bound in a mutually exclusive manner. The -14 T --> C mutation reduced HNF-6 binding. In transient transfection experiments, HNF-6 transactivated the wild-type protein C promoter and introduction of the mutation abolished transactivation by HNF-6. Similar experiments showed that wild-type protein C promoter activity was reduced by cotransfection of an HNF-1 expression vector. This inhibiting effect of HNF-1 was reversed to a stimulatory effect when promoter sequences either upstream or downstream of the HNF-6/HNF-1 site were deleted. It is concluded that HNF-6 is a major determinant of protein C gene activity. Moreover, this is the first report describing the putative involvement of HNF-6 and of an HNF-6 binding site in human pathology.
Spek
C A
CA
Hemostasis and Thrombosis Research Center, Department of Hematology, University Hospital, 2300 RC Leiden, The Netherlands. C.A.SPEK@AMC.UVA.NL
Lannoy
V J
VJ
Lemaigre
F P
FP
Rousseau
G G
GG
Bertina
R M
RM
Reitsma
P H
PH
D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D004268:DNA-Binding Proteins; D051537:Hepatocyte Nuclear Factor 1; D051538:Hepatocyte Nuclear Factor 1-alpha; D051539:Hepatocyte Nuclear Factor 1-beta; D051559:Hepatocyte Nuclear Factor 6; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D011486:Protein C / Q000235:genetics*; D020151:Protein C Deficiency; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C496487:HNF1A protein, human; C496495:HNF1B protein, human; D051538:Hepatocyte Nuclear Factor 1-alpha; D051559:Hepatocyte Nuclear Factor 6; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; C496605:ONECUT1 protein, human; D011486:Protein C; D015534:Trans-Activators; D014157:Transcription Factors; D051537:Hepatocyte Nuclear Factor 1; D051539:Hepatocyte Nuclear Factor 1-beta