Blood, Vol. 93 No. 1 (January 1), 1999:
pp. 363-369
Protein Replacement by Receptor-Mediated Endocytosis Corrects the
Sensitivity of Fanconi Anemia Group C Cells to Mitomycin C
Hagop Youssoufian,
Frank A.E. Kruyt, and
Xiaotong Li
From the Department of Molecular and Human Genetics and the
Department of Medicine, Baylor College of Medicine, Houston, TX.
Current methods for direct gene transfer into hematopoietic cells
are inefficient. Here we show that functional complementation of
Fanconi anemia (FA) group C cells by protein replacement can be as
efficacious as by transfection with wild-type FAC cDNA. We expressed a
chimeric protein (called His-ILFAC) consisting of the mature coding
portion of gibbon interleukin-3 (IL-3) and full-length FAC in
Escherichia coli. The purified bacterial protein is
internalized by hematopoietic cells via IL-3 receptors. The intracellular half-life of His-ILFAC is approximately 60 minutes, which
is comparable to that of the transgene-encoded FAC protein. In this
cell-culture model His-ILFAC completely corrects the sensitivity of FA
group C cells to mitomycin C, but it has no effect on FA cells that
belong to complementation groups A and B. We suggest that
receptor-mediated endocytosis of cytokine-fusion proteins may be of
general use to deliver macromolecules into hematopoietic progenitor
cells.
