Proceedings of the Japan Academy, Series B
Online ISSN : 1349-2896
Print ISSN : 0386-2208
ISSN-L : 0386-2208
Original Papers
Impairment in S-phase entry of splenocytes of Parp-1 knockout mice
Fumiaki WATANABEMitsuko MASUTANINobuo KAMADAHiroshi SUZUKIHitoshi NAKAGAMATakashi SUGIMURAHirobumi TERAOKA
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2003 Volume 79B Issue 8 Pages 248-251

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Abstract
One immediate cellular response to DNA damage is the polyADP-ribosylation reaction by poly(ADP-ribose) polymerase-1 (Parp-1). The importance of Parp-1 has been established in many cellular processes, such as the maintenance of genomic stability, DNA repair and cell-death induction. Here, we established Parp-1-/- mice of C57BL/6J congenic strain and characterized the role of Parp-1 in cell-cycle progression. In this study, we also improved a method to observe G0/G1 to S-phase transition of splenocytes and bone marrow cells prepared from mice. The cells were cultured and stimulated with mitogens (50 μM ionomycin/1 μM phorbol 12, 13-dibutyrate). We found that addition of a commercially available growth supportive reagent, BM Condimed RH1, greatly enhanced the transition of G0/G1 to the S-phase, which was determined by bromodeoxyuridine (BrdU) incorporation to DNA. Using this method, G0/G1 to the S-phase entry was measured using splenocytes derived from Parp-1-/-, Parp-1+/- and wild-type (Parp-1+/+) mice. DNA synthesis in Parp-1+/+ and Parp-1+/- splenocytes started from day 1 after addition of mitogens, whereas that in Parp-1-/- cells started from day 2. The peak of the S-phase was at day 2 in all genotypes and notably DNA synthesis in Parp-1-/- cells was approximately halved compared to Parp-1+/+ cells on day 2, 3 and 4. These results suggested that Parp-1 is involved in positive regulation of S-phase entry in quiescent mouse splenocytes.

(Contributed by Takashi SUGIMURA, M. J. A., Oct. 14, 2003)
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© 2003 The Japan Academy
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