Glucocorticoids regulate surfactant protein synthesis in a pulmonary adenocarcinoma cell line

M. A. O'Reilly, A. F. Gazdar, J. C. Clark, T. J. Pilot-Matias, S. E. Wert, W. M. Hull, J. A. Whitsett

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Synthesis of pulmonary surfactant proteins SP-A, SP-B, and SP-C was demonstrated in a cell line derived from a human adenocarcinoma of the lung. The cells contained numerous lamellar inclusion bodies and formed organized groups of cells containing well-developed junctional complexes and apical microvillous membranes. Synthesis of SP-A was detected in the cells by enzyme-linked immunoabsorbent assay assay and by immunoprecipitation of [35S]methionine-labeled protein. SP-A was identified as an M(r) 31,000-36,000 polypeptide containing asparagine-linked carbohydrate. Northern blot analysis detected SP-A mRNA of 2.2 kb. Dexamethasone (1-10 nM) enhanced the relative abundance of SP-A mRNA. Despite stimulation of SP-A mRNA, intracellular SP-A content was unaltered or inhibited by dexamethasone. SP-B and SP-C mRNAs and synthesis of the SP-B and SP-C precursors were markedly induced by dexamethasone. ProSP-B was synthesized and secreted primarily as an M(r) 42,000-46,000 polypeptide. Proteolysis of the proSP-B resulted in the generation of endoglycosidase F-sensitive M(r) = 19,000-21,000 and 25,000-27,000 peptides, which were detected both intra- and extracellularly. SP-C proprotein of M(r) = 22,000 and smaller SP-C fragments were detected intracellularly but were not detected in the media. Mature forms of SP-B (M(r) = 8,000) and SP-C (M(r) = 4,000) were not detected. Glucocorticoids directly enhance the relative synthesis and mRNA of the surfactant proteins SP-A, SP-B, and SP-C. Discrepancies among SP-A mRNA, its de novo synthesis, and cell content suggest that glucocorticoid may alter both pre- and posttranslational factors modulating SP-A expression.

Original languageEnglish (US)
Pages (from-to)1/3
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Volume257
Issue number6
StatePublished - 1989

Keywords

  • Northern blot analysis
  • enzyme-linked immunoabsorbent assay

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine
  • Physiology (medical)
  • Cell Biology

Fingerprint Dive into the research topics of 'Glucocorticoids regulate surfactant protein synthesis in a pulmonary adenocarcinoma cell line'. Together they form a unique fingerprint.

Cite this