DNA repair enzymes in the brain: DNA polymerase ß and poly(ADP-ribose) polymerase

DNA polymerase beta (DNA pol beta) has long been considered the enzyme responsible for synthesis of DNA after excision of damaged sites. In the 1970s DNA pol beta was isolated and characterized as the major DNA polymerase occurring in neuronal nuclei. Later studies reported that the neurons possess higher DNA pol beta activity than do astroglial and oligodendroglial cells.Poly (ADP-ribose) polymerase (pADPRP), as well as DNA pol beta, is an activev housekeeping enzyme involved in those cellular processes activated following DNA breakage. The variety of roles ascribed to pADPRP is due in part to its unquestionableversatility and in part to the as yet lacking and conflicting information about its functions. We previously analyzed the distribution pattern of the mRNA levels of two enzymes in rat tissues: and we showed that almost parallel amounts of themRNAs for pADPRP and DNA pol beta can be found in the tissues examined.The present work investigates the expression of both DNA pol beta and pADPRP in the central nervous system using Northern blot analysis in conjunction with in situ hybridization and immunocytochemical method.