The mouse proto-oncogene Pim-1, which encodes two cytoplasmic serine-threonine-specific protein kinases, is frequently activated by proviral insertion in murine leukemia virus-induced hematopoietic tumors. Transgenic mice overexpressing Pim-1 show a low incidence of spontaneous T cell lymphomas, whereas null mutant mice lack an obvious phenotype. We have analyzed the early B lymphoid compartment from both null mutant and E mu-Pim-1 transgenic mice. The level of Pim-1 expression appears to be a determining factor in the ability of these cells to respond to the growth factors interleukin 7 (IL-7) and SF (steel factor). The impaired response in null mutant mice could be rescued by introduction of a functional Pim-1 transgene. Moreover, overexpression of Pim-1 facilitates the derivation of primitive lymphoid cell lines that are dependent on combined stimulation with IL-7 and SF or insulin-like growth factor 1. These results for the first time identify the involvement of Pim-1 in a normal cellular function, as an important regulator of early B lymphopoiesis in mice.
Pim-1 levels determine the size of early B lymphoid compartments in bone marrow.
J Domen, N M van der Lugt, D Acton, P W Laird, K Linders, A Berns; Pim-1 levels determine the size of early B lymphoid compartments in bone marrow.. J Exp Med 1 November 1993; 178 (5): 1665–1673. doi: https://doi.org/10.1084/jem.178.5.1665
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