Cell cycle-dependent modulation of O6-methylguanine-DNA methyltransferase in C3H/10T1/2 cells.
O6-methylguanine-DNA methyltransferase (MGMT) was measured in partially synchronized cultures of C3H/10T1/2 mouse embryo cells as a function of cell cycle. The degree of synchrony and progression of the cell cycle were monitored by flow cytometry. The MGMT level was significantly reduced prior to the onset of S-phase. This reduction was concomitant with the inhibition of in vivo repair of O6-methylguanine in DNA of S-phase cells as observed earlier. The recovery of the MGMT level paralleled the progression of synchronized cells into G2. S-phase cells purified by cell sorting contained approximately 15% of the MGMT present in G0 or early G1 cells. A comparison of the in vivo repair of O6-methylguanine and MGMT levels suggests that the lack of repair of O6-methylguanine in DNA of the mouse embryo cells is due only in part to a temporal loss of MGMT.
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D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D002478:Cells, Cultured; D004260:DNA Repair; D004622:Embryo, Mammalian; D006147:Guanine / Q000031:analogs & derivatives / Q000378:metabolism; D008769:Methylnitronitrosoguanidine; D008780:Methyltransferases / Q000032:analysis*; D051379:Mice; D008809:Mice, Inbred C3H; D019853:O(6)-Methylguanine-DNA Methyltransferase
D008769:Methylnitronitrosoguanidine; D006147:Guanine; C008449:O-(6)-methylguanine; D008780:Methyltransferases; D019853:O(6)-Methylguanine-DNA Methyltransferase