Severe factor VII deficiency due to a mutation disrupting a hepatocyte nuclear factor 4 binding site in the factor VII promoter.
Although small deletions, splice site abnormalities, missense, and nonsense mutations have been identified in patients with factor VII deficiency, there have been no reports of mutations in the factor VII promoter. We investigated a girl with factor VII levels that were less than 1% of normal in association with a severe bleeding diathesis. The patient is homozygous for a T to G transversion that occurs 61 bp before the translation start site. This nucleotide is in a sequence that is an hepatocyte nuclear factor 4 (HNF-4) binding site within the factor VII promoter (ACTTTG AE-->ACGTTG). Using gel mobility shift assays, we show that the mutation disrupts the binding of HNF-4 to its cognate binding site. In growth hormone reporter gene assays, the activity of a plasmid containing the mutant promoter was 6.7% of the wild-type promoter plasmid. Although HNF-4 was able to transactivate the wild-type factor VII promoter 5.4-fold in HeLa cells, no transactivation could be shown with the mutant promoter. These findings indicate that HNF-4 exerts a major positive regulatory effect on factor VII expression and provides in vivo evidence that binding of this transcription factor is critical for normal factor VII expression.
Arbini
A A
AA
Department of Medicine, Brockton-West Roxbury Department of Veterans Affairs Medical Center, MA, USA.
Pollak
E S
ES
Bayleran
J K
JK
High
K A
KA
Bauer
K A
KA
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D001665:Binding Sites; D002648:Child; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins; D005167:Factor VII / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D005168:Factor VII Deficiency / Q000235:genetics*; D005786:Gene Expression Regulation; D006367:HeLa Cells; D051557:Hepatocyte Nuclear Factor 4; D006801:Humans; D010750:Phosphoproteins / Q000378:metabolism* / Q000502:physiology; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000378:metabolism* / Q000502:physiology; D015533:Transcriptional Activation
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D051557:Hepatocyte Nuclear Factor 4; C403128:MLX protein, human; D010750:Phosphoproteins; D014157:Transcription Factors; D005167:Factor VII; D004247:DNA