DNA-polymerase α, β, δ and ε activities in isolated neuronal and astroglial cell fractions from developing and aging rat cerebral cortex

Abstract

The relative proportions of DNA-polymerases α, β, δ and ε (pols α, β, δ and ε) activities in isolated neuronal and astroglial cell fractions from developing, adult and aging rat brain cerebral cortex, were examined. This was achieved through a protocol that takes advantage of the reported differential sensitivities of different DNA-polymerases towards certain inhibitors like butylphenyl and butylanilino nucleotide analogs, 2′,3′-dideoxythymidine triphosphate (ddTTP), monoclonal antibody of human α polymerase and the use of two template primers as substrates. The results indicate that while DNA-polymerase β (pol β) is the predominant enzyme, significant levels of DNA-polymerases α and δ/ε (pols α and δ/ε) are also present in both cell types at all the post-natal ages studied. A notable difference regarding the relative abundance of DNA-polymerases other than β is the higher percentage of pol δ/ε in neurons and a more sustained pol α activity through the life span in astroglia. The presence of detectable proportion of DNA-polymerases other than β (particularly the δ/ε type) may be taken to indicate their role in long patch base excision repair as well as in other modes of DNA repair.