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Mol. Cell. Biol., May 1995, 2402-2412, Vol 15, No. 5
J Hannemann, T Hara, M Kawai, A Miyajima, W Ostertag and C Stocking
An amino-terminally truncated beta C receptor (beta C-R) subunit of the
interleukin-3 (IL3)/granulocyte-macrophage colony-stimulating factor/IL5
receptor complex mediates factor-independent and tumorigenic growth in two
spontaneous mutants of a promyelocytic cell line. The constitutive
activation of the JAK2 protein kinase in these mutants confirms that
signaling occurs through the truncated receptor protein. Noteworthily, in
addition to a 10-kb deletion in the beta C-R subunit gene encoding the
truncated receptor, several secondary and independent mutations that result
in the deletion or functional inactivation of the allelic beta C-R subunit
and the closely related beta IL3-R subunit genes were observed in both
mutants, suggesting that such mutations are necessary for the full
oncogenic penetrance of the truncated beta C-R subunit. Reversion of these
mutations by the expression of the wild- type beta C-R in the two mutants
resulted in a fivefold decrease in cloning efficiency of the mutants in the
absence of IL3, confirming a functional interaction between the wild-type
and truncated proteins. Furthermore, expression of the truncated beta C-R
subunit in factor- dependent myeloid cells did not immediately render the
cells autonomous but increased the spontaneous frequency to
factor-independent growth by 4 orders of magnitude. Implications for both
leukemogenic progression and receptor-subunit interaction and signaling are
discussed.
Copyright © 1995, American Society for Microbiology
Sequential mutations in the interleukin-3 (IL3)/granulocyte-macrophage colony-stimulating factor/IL5 receptor beta-subunit genes are necessary for the complete conversion to growth autonomy mediated by a truncated beta C subunit
Abteilung der Zell- und Virusgenetik, Heinrich-Pette-Institut fur Experimentelle Virologie und Immunologie, Hamburg, Germany.
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