Hypertonic stress regulates amino acid transport and cell cycle proteins in chick embryo hepatocytes

Authors

  • Giovannella Bruscalupi,

    Corresponding author
    1. Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, P. le A. Moro 5, 00185 Rome, Italy
      These authors contributed equally to this work.
    Search for more papers by this author
  • Mara Massimi,

    Corresponding author
    1. Department of Basic and Applied Biology, University of LAquila, 67100 LAquila, Italy
      These authors contributed equally to this work.
    Search for more papers by this author
  • Silvana Spagnuolo,

    1. Department of Human Physiology and Pharmacology, Sapienza University of Rome, P. le A. Moro 5, 00185 Rome, Italy
    Search for more papers by this author
  • Anna Maria Fiore,

    1. Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, P. le A. Moro 5, 00185 Rome, Italy
    Search for more papers by this author
  • Silvia Leoni

    Corresponding author
    1. Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, P. le A. Moro 5, 00185 Rome, Italy
      To whom correspondence should be addressed (email silvia.leoni@uniroma1.it).
    Search for more papers by this author

These authors contributed equally to this work.

To whom correspondence should be addressed (email silvia.leoni@uniroma1.it).

Abstract

Hyperosmotic stress affects cell growth, decreasing cell volume and increasing the uptake of organic osmolytes. However, the sensitivity of embryonic cells to osmotic treatment remains to be established. We have analysed some aspects of cell-cycle control and amino-acid transport in hypertonic conditions during prenatal life. The effects of hyperosmotic stress on amino-acid uptake mediated by system A, 3H-thymidine incorporation, and regulation of cell-cycle proteins were analysed in chick embryo hepatocytes. Hypertonic stress increased system A activity and caused cell-cycle delay. Effects on amino-acid transport involved p38 kinase activation and new carrier synthesis. Cyclin D1, cdk4 (cyclin-dependent kinase 4) and PCNA (proliferating-cell nuclear antigen) levels decreased, whereas cyclin E, p21 and p53 levels were unchanged. Incorporation of 3H-leucine indicated decreased synthesis of cyclin D1. In contrast, analysis of mRNA by qRT-PCR (quantitative real-time PCR) showed a net increase of cyclin D1 transcripts, suggesting post-transcriptional regulation. The data show that chick embryo hepatocytes respond to hyperosmotic conditions by arresting cell growth to prevent DNA damage and increasing osmolyte uptake to regulate cell volume, indicating that the adaptive response to environmental stress exists during prenatal life.

Ancillary