Steroid-regulated intracellular signals involved in proliferation of rat epithelial cells. II. Glucocorticoid regulation of phosphoprotein maturation in rat hepatoma cells

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6650529

Vallerga, A K

Cultured BDS1 rat hepatoma cells, growth-arrested in the presence of serum and glucocorticoid, were induced to synchronously enter the cell cycle upon removal of steroid from the medium. Analysis of total RNA isolated from the proliferating cells revealed a peak of transcript levels at 0.5 hours for c-fos, at 2 hours for c-myc and at 8 hours for both c-ras{sup Ha} and c-ras{sup Ki}. The onset of DNA synthesis, as measured by ({sup 3}H)thymidine incorporation, occurred after an 8 hour time lag and peaked at 16 hours after the removal of dexamethasone. The induction of DNA polymerase alpha activity occurred during the onset of DNA synthesis and peaked at 24 hours. Cytoplasmic extracts from non-growing BDS1 cells did not contain an inhibitory activity that could suppress the activity of DNA polymerase alpha. A high molecular weight (M{sub r}210,000) DNA polymerase alpha protein was present in proliferating but not in quiescent cell extracts. In M1.54 rat liver hepatoma cells that contain mouse mammary tumor provirus (MMTV), the phosphorylated viral precursor polypeptide (Pr74), is cleaved posttranslationally into p24, after a 4 hour exposure to glucocortocoid. Twenty hours after hormone withdrawal, p24 is degraded whereas Pr74 remained ten-fold over its basal level.

• Research Organization: California Univ., Berkeley, CA (USA)
• OSTI ID: 6650529
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADRENAL HORMONES
ANIMAL CELLS
ANIMAL TISSUES
ANIMALS
AZINES
BIOLOGICAL FUNCTIONS
BODY
CELL CYCLE
CELL PROLIFERATION
CORTICOSTEROIDS
DIGESTIVE SYSTEM
DISEASES
DNA POLYMERASES
DNA REPLICATION
ENZYME ACTIVITY
ENZYMES
EPITHELIUM
FUNCTIONS
GLANDS
GLUCOCORTICOIDS
HEPATOMAS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
KETONES
LIVER
MAMMALS
MAMMARY GLANDS
MOLECULAR WEIGHT
NEOPLASMS
NUCLEIC ACID REPLICATION
NUCLEIC ACIDS
NUCLEOSIDES
NUCLEOTIDES
NUCLEOTIDYLTRANSFERASES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PHOSPHOPROTEINS
PHOSPHORUS-GROUP TRANSFERASES
POLYMERASES
POST-TRANSLATION MODIFICATION
PREGNANES
PROTEINS
PYRIMIDINES
RATS
RIBOSIDES
RNA
RODENTS
STEROIDS
THYMIDINE
TISSUES
TRACER TECHNIQUES
TRANSCRIPTION
TRANSFERASES
TRITIUM COMPOUNDS
TUMOR CELLS
VERTEBRATES