The Journal of Allergy and Clinical Immunology
Volume 123, Issue 3 , Pages 639-645, March 2009

Impaired translation of CCAAT/enhancer binding protein α mRNA in bronchial smooth muscle cells of asthmatic patients

  • Peter Borger, PhD

      Affiliations

    • Pulmonary Cell Research, Department of Biomedicine, University Hospital Basel, Basel, Switzerland
    • Corresponding Author InformationReprint requests: Peter Borger, PhD, Pulmonary Cell Research, University of Basel, Department of Biomedicine, Hebelstrasse 20, CH-4031 Basel, Switzerland.
    • ,
  • Nicola Miglino, MSc

      Affiliations

    • Pulmonary Cell Research, Department of Biomedicine, University Hospital Basel, Basel, Switzerland
    • ,
  • Melissa Baraket, MBBS, PhD, FRACP

      Affiliations

    • Pharmacology, University of Sydney, Sydney, Australia
    • ,
  • Judith L. Black, MBBS, PhD, FRACP

      Affiliations

    • Pharmacology, University of Sydney, Sydney, Australia
    • ,
  • Michael Tamm, MD

      Affiliations

    • Pulmonary Cell Research, Department of Biomedicine, University Hospital Basel, Basel, Switzerland
    • ,
  • Michael Roth, PhD

      Affiliations

    • Pulmonary Cell Research, Department of Biomedicine, University Hospital Basel, Basel, Switzerland
    • Woolcock Institute of Medical Research, University of Sydney, Sydney, Australia

Received 21 May 2008; received in revised form 10 November 2008; accepted 11 November 2008. published online 05 January 2009.

Background

Bronchial smooth muscle (BSM) cells of asthmatic patients have an impaired expression of CCAAT/enhancer binding protein (C/EBP) α, which is associated with increased proliferation.

Objective

We sought to assess the translational regulation of CEBPA mRNA in cultured BSM cells of healthy control subjects (n = 11) and asthmatic patients (n = 12).

Methods

Translation efficiency was studied by using a translation control reporter system driven by the control elements present in the CEBPA mRNA. Translation efficiency was determined by the ratio of 2 artificial hemagglutinin (HA.11) proteins: p23 and p12. We also analyzed levels of proteins that control translation of CEBPA mRNA, namely heterogeneous nuclear ribonucleoprotein E2, calreticulin, eukaryotic translation initiation factor (eIF4E), and 4E binding protein.

Results

Compared with healthy control subjects, BSM cells of asthmatic patients proliferate faster (2.1-fold) and are primed for IL-6 secretion. Real-time RT-PCR showed that BSM cells of asthmatic patients express normal levels of CEBPA mRNA, whereas they express lower levels of C/EBPα (p42). Transient transfections with the translation control reporter system construct showed a disturbed p12/p23 ratio in BSM cells of asthmatic patients relative to healthy control subjects, which coincided with lower levels of eIF4E.

Conclusion

BSM cells of asthmatic patients have normal levels of CEBPA mRNA but inadequately reinitiate the translation into C/EBPα. Impaired translation control upstream of eIF4E might underlie the observed increased proliferation and priming of BSM cells of asthmatic patients.

Key words: Asthma, bronchial smooth muscle cell hyperplasia, C/EBPα, messenger RNA translation

Abbreviations used: BSM, Bronchial smooth muscle, C/EBP, CCAAT/enhancer binding protein, 4EBP, 4E binding protein, eIF4E, Eukaryotic translation initiation factor 4E, HA, Hemagglutinin, hnRNPE2, Heterogeneous nuclear ribonucleoprotein E2, LP, Long peptide, mTOR, Mammalian target of rapamycin, PDGF, Platelet-derived growth factor, SP, Short peptide, TCRS, Translation control reporter system, uORF, Upstream open reading frame

 

 Supported by a grant of the Swiss National Foundation (grant no. SNF32-116022) and the Nora van Meeuven-Häfliger Stiftung. J.L.B. is supported by the National Health and Medical Research Council of Australia.

 Disclosure of potential conflict of interest: J. L. Black has received research support from the National Health and Medical Research Council (Australia), the Anonymous Charitable Trust, and the Rebecca Cooper Foundation. The rest of the authors have declared that they have no conflict of interest.

PII: S0091-6749(08)02180-5

doi:10.1016/j.jaci.2008.11.006

The Journal of Allergy and Clinical Immunology
Volume 123, Issue 3 , Pages 639-645, March 2009

Article Tools

* Image Usage & Resolution