title: A new isoform of interleukin-3 receptor {alpha} with novel differentiation activity and high affinity binding mode.
abstract: Interleukin-3 (IL-3) promotes both self-renewal and differentiation of early multipotential progenitors and is involved in inducible hematopoiesis in response to infections. Here we report new insights into these processes with the identification of a new isoform (SP2) of IL-3 receptor alpha (IL-3Ralpha), present in mouse and human hematopoietic cells, which lacks domain 1 of the full-length receptor (SP1). Binding assays with beta(IL-3) mutants showed that mouse SP2 uses a different high affinity binding mode to SP1, although both mouse and human SP2 and SP1 can stimulate IL-3-dependent growth. In IL-3-dependent differentiation models, human SP2 and SP1 gave differential effects on lineage commitment or self-renewal dependent on the cellular context, suggesting that different modes of ectodomain binding may modulate intracellular signaling. In a multipotential factor dependent cell-Paterson mix, the transcription factors C/EBPalpha and PU.1 and microRNAs miRNA-15a, -223, and -181a were up-regulated in cells undergoing SP2-supported differentiation compared with SP1-supported self-renewal. Similarly in M1 cells, SP2 promoted differentiation compared with SP1 and gave up-regulation of PU.1 and miRNA-155 and -223. These findings suggest that IL-3-promoted lineage commitment uses similar mechanisms to those of steady-state hematopoiesis. Both the SP1 and SP2 isoforms activated the Jak2/STAT5, Akt, and Erk1/2 signaling pathways in M1 cells, although the activation was more prolonged for the SP2 isoform.
authors.affiliation: Division of Molecular Bioscience, The John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
authors.forename: Jinglong
authors.initials: J
authors.lastname: Chen
authors.forename: Jane
authors.initials: J
authors.lastname: Olsen
authors.forename: Sally
authors.initials: S
authors.lastname: Ford
authors.forename: Shamaruh
authors.initials: S
authors.lastname: Mirza
authors.forename: Andrew
authors.initials: A
authors.lastname: Walker
authors.forename: James M
authors.initials: JM
authors.lastname: Murphy
authors.forename: Ian G
authors.initials: IG
authors.lastname: Young
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D005434:Flow Cytometry; D006031:Glycosylation; D006801:Humans; D053650:Interleukin-3 Receptor alpha Subunit / Q000235:genetics / Q000378:metabolism*; D053614:Janus Kinase 2 / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D035683:MicroRNAs / Q000494:pharmacology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D020033:Protein Isoforms; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D016185:Receptors, Interleukin-3 / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050799:STAT5 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism
chemical_list: C115022:IL3RA protein, human; D053650:Interleukin-3 Receptor alpha Subunit; D035683:MicroRNAs; D020033:Protein Isoforms; D016185:Receptors, Interleukin-3; D050799:STAT5 Transcription Factor; D014157:Transcription Factors; D053614:Janus Kinase 2; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3