Age dependency of the metabolic conversion of polyamines into amino acids in IMR-90 human embryonic lung diploid fibroblasts
When radioactive polyamines (putrescine or spermidine) were incubated with mammalian cells in tissue culture, the radioactivity was incorporated into cellular proteins via two different metabolic pathways; one is metabolic labeling of an 18,000-dalton protein via hypusine formation, and the other is general protein synthesis employing radioactive amino acids derived from biodegradation of polyamines via GABA shunt and Krebs cycle. Aminoguanidine, a potent inhibitor of diamine oxidase, blocked the metabolic conversion of polyamines to amino acids but had no effect on the metabolic labeling of the 18,000-dalton protein. The authors have investigated these two polyamine-associated biochemical events in IMR-90 human diploid fibroblasts as a function of their population doubling level (PDL). They found that (1) the metabolic labeling of the 18,000-dalton protein was about two-fold greater in young cells (PDL = 22) than that in old cells (PDL = 48), and (2) the metabolic labeling of other cellular proteins, employing amino acids derived from putrescine via polyamine catabolic pathway, was more than six-fold greater in the old cells (PDL = 48) than in the young cells (PDL = 22). Since the rate of protein synthesis was about 1.4-fold higher in the young cells as compared to the old cells, their data indicated that the activity of catabolic conversion of putrescine (or spermidine) to amino acids in old IMR-90 cells was about eight-fold greater than that in young cells. This remarkable increase of polyamine catabolism and the slight decrease of metabolic labeling of the 18,000-dalton protein were also observed in cell strains derived from patients with premature aging disease.
- Research Organization:
- Rutgers-The State Univ. of New Jersey, Piscataway
- OSTI ID:
- 6942632
- Journal Information:
- J. Cell. Physiol.; (United States), Journal Name: J. Cell. Physiol.; (United States) Vol. 128:1; ISSN JCLLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
AGE DEPENDENCE
AMINES
AMINO ACIDS
ANIMAL CELLS
ANIMALS
BIODEGRADATION
BIOLOGICAL PATHWAYS
BODY
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CONNECTIVE TISSUE CELLS
DECOMPOSITION
EMBRYONIC CELLS
FIBROBLASTS
LABELLED COMPOUNDS
LUNGS
MAMMALS
MAN
METABOLISM
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PRIMATES
PUTRESCINE
RESPIRATORY SYSTEM
SOMATIC CELLS
SPERMIDINE
VERTEBRATES