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Involvement of proliferating cell nuclear antigen (Cyclin) in DNA replication in living cells

Journal Article · · Mol. Cell. Biol.; (United States)
DOI:https://doi.org/10.1128/MCB.9.1.57· OSTI ID:5604407

Proliferating cell nuclear antigen (PCNA) (also called cyclin) is known to stimulate the activity of DNA polymerase /delta/ but not the other DNA polymerases in vitro. The authors injected a human autoimmune antibody against PCNA into unfertilized eggs of Xenopus laevis and examined the effects of this antibody on the replication of injected plasmid DNA as well as egg chromosomes. The anti-PCNA antibody inhibited plasmid replication by up to 67%, demonstrating that PCNA is involved in plasmid replication in living cells. This result further implies that DNA polymerase /delta/ is necessary for plasmid replication in vivo, Anti-PCNA antibody alone did not block plasmid replication completely, but the residual replication was abolished by coinjection of a monoclonal antibody against DNA polymerase /alpha/. Anti-DNA polymerase /alpha/ alone inhibited plasmid replication by 63%. Thus, DNA ploymerase /alpha/ is also required for plasmid replication in this system. In similar studies on the replication of egg chromosomes, the inhibition by anti-PCNA antibody was only 30%, while anti-DNA polymerase /alpha/ antibody blocked 73% of replication. They concluded that the replication machineries of chromosomes and plasmid differ in their relative content of DNA polymerase /delta/. In addition, they obtained evidence through the use of phenylbutyl deoxyguanosine, an inhibitor of DNA polymearse /alpha/, that the structure of DNA polymerase /alpha/ holoenzyme for chromosome replication is significantly different from that for plasmid replication.

Research Organization:
Dept. of Internal Medicine and Nephrology, Steglitz Medical Center, Free Univ. of Berlin, 1000 Berlin 45 (DE); Scripps Clinic and Research Foundation, La Jolla, CA (USA)
OSTI ID:
5604407
Journal Information:
Mol. Cell. Biol.; (United States), Journal Name: Mol. Cell. Biol.; (United States) Vol. 9:1; ISSN MCEBD
Country of Publication:
United States
Language:
English