Glucocorticoids regulate surfactant protein synthesis in a pulmonary adenocarcinoma cell line
- Children's Hospital, Cincinnati, OH (USA)
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 and by immunoprecipitation of (35S)methionine-labeled protein. SP-A was identified as an Mr 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 Mr 42,000-46,000 polypeptide. Proteolysis of the proSP-B resulted in the generation of endoglycosidase F-sensitive Mr = 19,000-21,000 and 25,000-27,000 peptides, which were detected both intra- and extracellularly. SP-C proprotein of Mr = 22,000 and smaller SP-C fragments were detected intracellularly but were not detected in the media. Mature forms of SP-B (Mr = 8,000) and SP-C (Mr = 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.
- OSTI ID:
- 7168321
- Journal Information:
- American Journal of Physiology; (USA), Vol. 257; ISSN 0002-9513
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GLUCOCORTICOIDS
BIOCHEMICAL REACTION KINETICS
LUNGS
CARCINOMAS
PROTEINS
BIOSYNTHESIS
CELL MEMBRANES
DEXAMETHASONE
DNA
ELECTRON MICROSCOPY
ENZYME IMMUNOASSAY
MAN
MESSENGER-RNA
METHIONINE
SULFUR 35
SURFACTANTS
TRACER TECHNIQUES
TUMOR CELLS
ADRENAL HORMONES
AMINO ACIDS
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOASSAY
BODY
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CORTICOSTEROIDS
DAYS LIVING RADIOISOTOPES
DISEASES
DRUGS
EVEN-ODD NUCLEI
HYDROXY COMPOUNDS
IMMUNOASSAY
ISOTOPE APPLICATIONS
ISOTOPES
KETONES
KINETICS
LIGHT NUCLEI
LIPOTROPIC FACTORS
MAMMALS
MEMBRANES
MICROSCOPY
NEOPLASMS
NUCLEI
NUCLEIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANS
PREGNANES
PRIMATES
RADIOISOTOPES
REACTION KINETICS
RESPIRATORY SYSTEM
RNA
STEROIDS
SULFUR ISOTOPES
SYNTHESIS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques