Document 0161
 DOCN  M9580161
 TI    Expression of the blood-clotting factor-VIII cDNA is repressed by a
       transcriptional silencer located in its coding region.
 DT    9506
 AU    Hoeben RC; Fallaux FJ; Cramer SJ; van den Wollenberg DJ; van Ormondt H;
       Briet E; van der Eb AJ; Department of Medical Biochemistry, University
       of Leiden, The; Netherlands.
 SO    Blood. 1995 May 1;85(9):2447-54. Unique Identifier : AIDSLINE
       MED/95244865
 AB    Hemophilia A is caused by a deficiency of factor-VIII procoagulant
       (fVIII) activity. The current treatment by frequent infusions of
       plasma-derived fVIII concentrates is very effective but has the risk of
       transmittance of blood-borne viruses (human immunodeficiency virus
       [HIV], hepatitis viruses). Use of recombinant DNA-derived fVIII as well
       as gene therapy could make hemophilia treatment independent of
       blood-derived products. So far, the problematic production of the fVIII
       protein and the low titers of the fVIII retrovirus stocks have prevented
       preclinical trials of gene therapy for hemophilia A in large-animal
       models. We have initiated a study of the mechanisms that oppose
       efficient fVIII synthesis. We have established that fVIII cDNA contains
       sequences that dominantly inhibit its own expression from retroviral as
       well as from plasmid vectors. The inhibition is not caused by
       instability of the fVIII mRNA (t1/2, > or = 6 hours) but rather to
       repression at the level of transcription. A 305-bp fragment is
       identified that is involved in but not sufficient for repression. This
       fragment does not overlap the region recently identified by Lynch et al
       (Hum Gene Ther 4:259, 1993) as a dominant inhibitor of RNA accumulation.
       The repression is mediated by a cellular factor (or factors) and is
       independent of the orientation of the element in the transcription unit,
       giving the repressor element the hallmarks of a transcriptional
       silencer.
 DE    Amino Acid Sequence  Cell Line  DNA, Complementary/GENETICS  DNA,
       Recombinant  Factor VIII/*BIOSYNTHESIS/GENETICS  *Gene Expression
       Regulation  Half-Life  Hela Cells  Human  Molecular Sequence Data
       Polarity of Translation  Recombinant Fusion Proteins/BIOSYNTHESIS
       *Regulatory Sequences, Nucleic Acid  RNA, Messenger/METABOLISM  Support,
       Non-U.S. Gov't  *Transcription, Genetic  JOURNAL ARTICLE

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