A new isoform of interleukin-3 receptor {alpha} with novel differentiation activity and high affinity binding mode

J Biol Chem. 2009 Feb 27;284(9):5763-73. doi: 10.1074/jbc.M808197200. Epub 2008 Dec 24.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing*
  • Animals
  • Blotting, Western
  • COS Cells
  • Cell Differentiation*
  • Cell Proliferation
  • Cells, Cultured
  • Chlorocebus aethiops
  • Flow Cytometry
  • Glycosylation
  • Humans
  • Interleukin-3 Receptor alpha Subunit / genetics
  • Interleukin-3 Receptor alpha Subunit / metabolism*
  • Janus Kinase 2 / metabolism
  • Mice
  • Mice, Transgenic
  • MicroRNAs / pharmacology
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Protein Isoforms
  • Proto-Oncogene Proteins c-akt / metabolism
  • Receptors, Interleukin-3 / genetics
  • Receptors, Interleukin-3 / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • STAT5 Transcription Factor / metabolism
  • Signal Transduction*
  • Transcription Factors / metabolism

Substances

  • IL3RA protein, human
  • Interleukin-3 Receptor alpha Subunit
  • MicroRNAs
  • Protein Isoforms
  • Receptors, Interleukin-3
  • STAT5 Transcription Factor
  • Transcription Factors
  • Janus Kinase 2
  • Proto-Oncogene Proteins c-akt
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3