Protein turnover and cellular autophagy in growing and growth-inhibited 3T3 cells

Journal Article · Wed Jul 01 04:00:00 EDT 1987 · Experimental Cell Research; (USA)

DOI:https://doi.org/10.1016/0014-4827(87)90255-2· OSTI ID:6533545

Papadopoulos, T; Pfeifer, U ^[1]

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1. Univ. of Wuerzburg (West Germany)

The relationship between growth, protein degradation, and cellular autophagy was tested in growing and in growth-inhibited 3T3 cell monolayers. For the biochemical evaluation of DNA and protein metabolism, growth-inhibited 3T3 cell monolayers with high cell density and growing 3T3 cell monolayers with low cell density were labeled simultaneously with ({sup 14}C)thymidine and ({sup 3}H)leucine. The evaluation of the DNA turnover and additional ({sup 3}H)thymidine autoradiography showed that 24 to 5% of 3T3 cells continue to replicate even in the growth-inhibited state, where no accumulation of protein and DNA can be observed. Cell loss, therefore, has to be assumed to compensate for the ongoing cell proliferation. When the data of protein turnover were corrected for cell loss, it was found that the rate constant of protein synthesis in nongrowing monolayers was reduced to half the value found in growing monolayers. Simultaneously, the rate constant of protein degradation in nongrowing monolayers was increased to about 1.5-fold the value of growing monolayers. These data are in agreement with the assumption that cellular autophagy represents a major pathway of regulating protein degradation in 3T3 cells and that the regulation of autophagic protein degradation is of relevance for the transition from a growing to a nongrowing state.

• OSTI ID: 6533545
• Journal Information: Experimental Cell Research; (USA), Journal Name: Experimental Cell Research; (USA) Vol. 171:1; ISSN ECREA; ISSN 0014-4827
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ANIMAL CELLS
ANIMALS
AUTORADIOGRAPHY
AZINES
BIODEGRADATION
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
CELL CYCLE
CHEMICAL REACTIONS
CONNECTIVE TISSUE CELLS
DECOMPOSITION
DNA
FIBROBLASTS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
LABELLED COMPOUNDS
LEUCINE
MAMMALS
MICE
NUCLEIC ACIDS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PROTEINS
PYRIMIDINES
RIBOSIDES
RODENTS
SOMATIC CELLS
THYMIDINE
TRITIUM COMPOUNDS
VERTEBRATES