Ornithine Decarboxylase Activity in Brain Regulated by a Specific Macromolecul, the Antizyme

Abstract

Mouse brain ornithine decarboxylase activity is about 70-fold higher at the time of birth compared with that of adult mice. Enzyme activity declines rapidly after birth and reaches the adult level by 3 weeks. Immunoreactive enzyme concentration parallels very closely the decrease of enzyme activity during the first postnatal week, remaining constant thereafter. The content of brain antizyme, the macromolecular inhibitor to ornithine decarboxylase, in turn is very low during the first 7 days and starts then to increase and at the age of 3 weeks it is about six times the level of that in newborn mice. This may explain the decrease in enzyme activity during brain maturation, and suggests the regulation of polyamine biosynthesis by an antizyme-mediated mechanism in adult brain.

Brain Neurons Express Ornithine Decarboxylase‐Activating Antizyme Inhibitor 2 with Accumulation in Alzheimer's Disease

“…In addition to neural cells, we have detected the expression of AZIN2 in Leydig cells and in mast cells (56,57) both of which are terminally differentiated cells. Most of the ODC in the brain is bound to AZ that blocks its enzymatic activity (26)(27)(28). However, various stimuli, including electrical and chemical stimulation, and traumatic injuries, activate ODC (2,7,12,35,44).…”

Expression of a Novel Human Ornithine Decarboxylase-like Protein in the Central Nervous System and Testes

“…In the adult brain, where the physiological cell turnover is slow, the activity and expression of ODC varies between different parts of the organ (8,9). There is a general discrepancy between the relatively high amounts of ODC protein in the central nervous system (CNS) and its low or modest catalytic activity (10). Kilpelä inen and Hietala (11) found that in the adult rat brain, ODC could be activated by GTP and that the activity was partially resistant to treatment with the ODC inhibitor, ␣-difluoromethyl ornithine (DFMO).…”

Expression of ODC and its regulatory protein antizyme in the adult rat brain

“…After cerebral ischemia ODC is up-regulated also in regions where no cellular damage usually occurs (Keinänen et al, 1997). In mammalian brain, ODC activity is highest at birth and thereafter declines during the first weeks or months to a low adult level (Laitinen et al, 1982;Onoue et al, 1988;Morrison et al, 1998), although the amount of immunoreactive enzyme is still relatively high (Laitinen et al, 1985). In the adult brain a large amount of ODC is bound to the Az as an inactive complex and it has been suggested that the bound ODC represents the storage form of the enzyme that can be rapidly activated by dissociation for local needs (Laitinen et al, 1985(Laitinen et al, , 1986.…”