Termination Sites of fleplication Are Anchored to the Nuclear Matrix during S Phase in Mouse LPI-1 Cells

생쥐 LP1-1 세포에서 S phase 동안 nuclear matrix에 고정되어 있는 복제 끝점

The association of replication origins/termini with nuclear matrix during S phase was investigated by DNase digestion of halo structures in synchronized mouse LPI-1 cells. The binding of parental DNA to nuclear matrix was constant throughout S phase. When nuclear matrix was isolated from the cells pulse-labeled with 3H-thvmidine at various stases of S phase, total 3H-labels associated with nuclear matrix were specifically higher at So, Sa and Ss stages than other stases of S phase, suggesting that the newly synthesized DNAs at those stages are not excluded out of nuclear matrix. Similar patterns were obsenred from the pulse-chase experiments, in which cells were pulse-labeled at each stage of S phase and further incubated for 1 hr. These results suggest that the replication origins and termini are fixed at the nuclear matrix, and that the nuclear matrix binding fractions of DNA at 3C-pause may contain a large population of replication origins and termination sites.