IL-3 coordination of myeloblast function by modulating mRNA stability

The growth factor interleukin-3 (IL-3) promotes the survival and growth of multipotent hematopoietic progenitors and stimulates myelopoiesis. It has also been reported to oppose terminal granulopoiesis and to support leukemic cell growth through autocrine or paracrine mechanisms. We used kinetic microarray, Northern Blotting and bioinformatics analysis of IL-3 dependent myeloblasts to determine whether IL-3 acts in part by regulating the rate of turnover of mRNA transcripts in specific functional pathways. Our results indicate that exposure of myeloblasts to IL-3 causes immediate early stabilization of hundreds of transcripts in pathways relevant to myeloblast function. Examples include transcripts associated with proliferation and leukemic transformation (pik3cd, myb, pim-1), hematopoietic development (cited2), differentiation control (cdkn1a) and RNA processing (BRF1, BRF2). A domain in the 3-utr of IL-6 that mediates IL-3 responsiveness contains AU-rich elements that bind proteins known to modulate mRNA stability, however a known destabilizing protein (AUF1) is shown not to mediate degradation in the absence of IL-3. These findings support a model of IL-3 action through mRNA stability control and suggest that aberrant stabilization of this network of transcripts could contribute to growth patterns observed in leukemia.

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Ernst J, Ghanem L, Bar-Joseph Z, McNamara M, Brown J, Steinman RA