title: Hypertonic stress regulates amino acid transport and cell cycle proteins in chick embryo hepatocytes.
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, (3)H-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 (3)H-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.
authors: Department of Biology and Biotechnology 'Charles Darwin', Sapienza University of Rome, Italy.
authors: Giovannella
authors: G
authors: Bruscalupi
authors: Mara
authors: M
authors: Massimi
authors: Silvana
authors: S
authors: Spagnuolo
authors: Anna Maria
authors: AM
authors: Fiore
authors: Silvia
authors: S
authors: Leoni
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D018797:Cell Cycle Proteins / Q000378:metabolism*; D048429:Cell Size; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism; D019927:Cyclin E / Q000378:metabolism; D051358:Cyclin-Dependent Kinase 4 / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism; D006982:Hypertonic Solutions / Q000494:pharmacology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D013312:Stress, Physiological; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000596:Amino Acids; D018797:Cell Cycle Proteins; D019927:Cyclin E; D050759:Cyclin-Dependent Kinase Inhibitor p21; D006982:Hypertonic Solutions; D018809:Proliferating Cell Nuclear Antigen; D016159:Tumor Suppressor Protein p53; D019938:Cyclin D1; D051358:Cyclin-Dependent Kinase 4; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases