Spermidine mediates degradation of ornithine decarboxylase by a non-lysosomal, ubiquitin-independent mechanism

Journal Article · Thu Jan 01 04:00:00 EST 1987 · J. Cell. Physiol.; (United States)

DOI:https://doi.org/10.1002/jcp.1041300119· OSTI ID:6528200

Glass, J R; Gerner, E W

The mechanism of spermidine-induced ornithine decarboxylase (OCD, E.C. 4.1.1.17) inactivation was investigated using Chinese hamster ovary (CHO) cells, maintained in serum-free medium, which display a stabilization of ODC owing to the lack of accumulation of putrescine and spermidine. Treatment of cells with 10 ..mu..M exogenous spermidine leads to rapid decay of ODC activity accompanied by a parallel decrease in enzyme protein. Analysis of the decay of (/sup 35/S)methionine-labeled ODC and separation by two-dimensional electrophoresis revealed no detectable modification in ODC structure during enhanced degradation. Spermidine-mediated inactivation of ODC occurred in a temperature-dependent manner exhibiting pseudo-first-order kinetics over a temperature range of 22-37/sup 0/C. In cultures treated continuously, an initial lag was observed after treatment with spermidine, followed by a rapid decline in activity as an apparent critical concentration of intracellular spermidine was achieved. Treating cells at 22/sup 0/C for 3 hours with 10 ..mu.. M spermidine, followed by removal of exogenous polyamine, and then shifting to varying temperatures, resulted in rates of ODC inactivation identical with that determined with a continuous treatment. Arrhenius analysis showed that polyamine mediated inactivation of ODC occurred with an activation energy of approximately 16 kcal/mol. Treatment of cells with lysosomotrophic agents had no effect of ODC degradation. ODC turnover was not dependent on ubiquitin-dependent proteolysis. These data support the hypothesis that spermidine regulates ODC degradation via a mechanism requiring new protein synthesis, and that this occurs via a non-lysosomal, ubiquitin-independent pathway.

• Research Organization: Univ. of Arizona Health Sciences Center, Tucson
• OSTI ID: 6528200
• Journal Information: J. Cell. Physiol.; (United States), Journal Name: J. Cell. Physiol.; (United States) Vol. 130:1; ISSN JCLLA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINES
AMINO ACIDS
ANIMAL CELLS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIODEGRADATION
BIOLOGICAL EFFECTS
CARBON 14 COMPOUNDS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBON-CARBON LYASES
CARBOXY-LYASES
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHALCOGENIDES
CHEMICAL REACTIONS
CHO CELLS
DAYS LIVING RADIOISOTOPES
DECARBOXYLASES
DECOMPOSITION
DRUGS
ENZYMES
EVEN-ODD NUCLEI
ISOTOPES
KINETICS
LABELLED COMPOUNDS
LIGHT NUCLEI
LIPOTROPIC FACTORS
LYASES
LYSOSOMES
METHIONINE
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANOIDS
OXIDES
OXYGEN COMPOUNDS
RADIOISOTOPES
REACTION KINETICS
SPERMIDINE
SULFUR 35
SULFUR ISOTOPES
TEMPERATURE DEPENDENCE