title: Effect of medium composition on protein degradation and DNA synthesis in rat embryo fibroblasts.
abstract: Fibroblasts in medium deficient in serum, amino acids, phosphate, or glucose stop synthesizing DNA and increase the rate of degradation of their long-lived cellular proteins approximately 2-fold. There is no difference in the rate of degradation of short-lived proteins under these conditions. Insulin, dexamethasone, and fibroblast growth factor act synergistically to inhibit protein degradation and to stimulate thymidine incorporation to about the same extent as serum. When the medium content in serum or fibroblast growth factor is varied over a wide range, there is a close, inverse correlation between the rate of protein degradation and the extent of thymidine incorporation. When serum is added to cells that have been deprived of serum, the inhibition of protein degradation is immediate whereas the enhanced rate of protein degradation in serum-free medium is attained within 1 hr after serum removal. A 30-min exposure to serum followed by incubation in serum-free medium was as effective as continuous exposure to serum in stimulating thymidine incorporation after 8-24 hr.
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003470:Culture Media; D004247:DNA / Q000096:biosynthesis*; D003907:Dexamethasone / Q000494:pharmacology; D004622:Embryo, Mammalian; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006133:Growth Substances / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D011247:Pregnancy; D011506:Proteins / Q000378:metabolism*; D051381:Rats
chemical_list: D003470:Culture Media; D006133:Growth Substances; D007328:Insulin; D011506:Proteins; D003907:Dexamethasone; D004247:DNA
references.citation: Proc Natl Acad Sci U S A. 1976 Jan;73(1):168-72
references.pmid: 813221
references.citation: J Biol Chem. 1972 Oct 25;247(20):6474-81
references.pmid: 5076767
references.citation: Proc Natl Acad Sci U S A. 1971 Dec;68(12):3154-7
references.pmid: 5289253
references.citation: Biochim Biophys Acta. 1976 Jan 8;419(1):112-9
references.pmid: 1244857
references.citation: J Biol Chem. 1975 Apr 10;250(7):2515-20
references.pmid: 1168187
references.citation: Proc Natl Acad Sci U S A. 1968 May;60(1):300-4
references.pmid: 5241531
references.citation: J Cell Physiol. 1969 Oct;74(2):191-202
references.pmid: 5358255
references.citation: J Cell Physiol. 1965 Dec;66(3):325-33
references.pmid: 5884360
references.citation: Proc Natl Acad Sci U S A. 1973 Oct;70(10):2819-22
references.pmid: 4517934
references.citation: Nat New Biol. 1971 Aug;232(33):206-11
references.pmid: 5285753
references.citation: Exp Cell Res. 1972 Oct;74(2):466-70
references.pmid: 4343022
references.citation: J Cell Biol. 1968 May;37(2):482-513
references.pmid: 4297786
references.citation: J Biol Chem. 1976 Jun 25;251(12):3586-93
references.pmid: 180001
references.citation: J Cell Physiol. 1976 Jan;87(1):111-21
references.pmid: 1399
references.citation: Proc Natl Acad Sci U S A. 1974 Jul;71(7):2908-11
references.pmid: 4527719
references.citation: Proc Natl Acad Sci U S A. 1974 Aug;71(8):2942-5
references.pmid: 4528490
references.citation: Eur J Biochem. 1974 Nov 15;49(2):325-32
references.pmid: 4474937
references.citation: J Supramol Struct. 1976;4(2):279-87
references.pmid: 177819
references.citation: Biochemistry. 1975 Nov 18;14(23):5199-204
references.pmid: 172118
references.citation: Science. 1975 Dec 19;190(4220):1213-5
references.pmid: 173021
references.citation: J Biol Chem. 1973 Sep 10;248(17):6221-6
references.pmid: 4737734
references.citation: Annu Rev Biochem. 1976;45:747-803
references.pmid: 786161