Expression of the antioxidant gene NKEF in the central nervous system

Free radicals and the oxidative stress they impose can cause serious injury in the nervous system and contribute to pathology associated with a wide variety of degenerative and traumatic disorders. In this study, we examined the expression of an antioxidant defense gene, nkef, in human tissue and isolated populations of rat brain cells using Western and Northern blot analysis. NKEF protein was expressed in human brain, liver, kidney, muscle, and lung. The human endothelial cell line ECV expressed a 25-kDa band in addition to the 22-kDa band normally observed. In the central nervous system, a 22-kDa NKEF band was present in cortical gray and white matter, hippocampus, cerebellum, and spinal cord in roughly similar amounts. Expression of NKEF-A and NKEF-B subtypes was evaluated by Northern analysis of cultured cell types from embryonic rat brain. Astrocyte and microglia expressed both 22- and 25-kDa bands, whereas cortical neurons and oligodendrocytes contained only the 22-kDa protein band. Northern blot analysis of these cell types revealed low levels of NKEF-A message in neurons and oligodendrocytes, and relatively low levels of NKEF-B in microglia. Differential expression of these antioxidant defense genes may contribute to the selective vulnerability of brain cell types to specific kinds of oxidative stress.