Variation of DNA polymerases - α , - β . and - γ during perinatal tissue growth and differentiation

Abstract

The activities of the three known DNA polymerases -α, β-, and -γ were determined in rat brain neurons, cardiac muscle and spleen, and were correlated with the rate of cell proliferation during perinatal development. In neurons and cardiac muscle, which stop dividing before birth, DNA polymerase-α activity drops sharply from a high level with the approach of term and disappears at approximately two weeks postnatal age. In contrast, α-polymerase activity is almost absent in spleen during late gestation, when the rate of cell division is low, and increases abruptly after birth with the sudden onset of cell proliferation. These data give further evidence for an involvement of DNA polymerase-α in DNA replication. DNA polymerase-β and -γ activities show essentially no correlation with the rate of cell division. Thus, these enzymes are probably responsible for repair type processes rather than for DNA replication.