Nuclear respiratory factor-2 subunit protein: correlation with cytochrome oxydase and regulation by functional activity in the monkey primary visual cortex

Abstract

Previous studies have shown that a transcription factor of the Ets family, nuclear respiratory factor 2 (NRF-2), can activate in vitro the gene expression of cytochrome oxidase (CO), a mitochondrial enzyme of oxidative metabolism. The goals of our present study were to determine whether the distribution of NRF-2 alpha subunit proteins correlated with that of CO activity in the macaque monkey visual cortex and whether the level could be perturbed by visual deprivation. We generated polyclonal antibodies specifically against human NRF-2 alpha subunit. In normal monkeys, patterns of NRF-2 alpha distribution resembled closely that of CO activity: 1) NRF-2 alpha immunoreactivity was localized in both nuclei and cytoplasm of neurons, but the levels differed among various laminae; 2) layers IVA, IVC, and VI, which had high CO activity, were labeled more densely by NRF-2 alpha than layers I, IVB, and V, which contained lower levels of both NRF-2 alpha and CO activity; and 3) CO-rich puffs in layers II and III contained a higher level of NRF-2 alpha than CO-poor interpuffs. From 1 day to 7 days after monocular impulse blockade with tetrodotoxin, there was a progressive reduction of NRF-2 alpha in deprived ocular dominance columns, in parallel with decreases in CO activity. These results suggest that local levels of NRF-2 in the monkey visual cortex closely reflect neuronal physiological and metabolic levels revealed by CO activity and that the expression of NRF-2 alpha, like that of CO, is regulated tightly by neural functional activity.