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Temporal order of replication of genes responsible for hypoxanthine phosphoribosyl transferase and Na + /K + ATPase in chemically transformed human fibroblasts
Author(s) -
Tsutsui Takeki,
Suzuki Nobuko,
Elmore Eugene,
Maizumi Heiji
Publication year - 1986
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041270316
Subject(s) - cytotoxic t cell , bromodeoxyuridine , microbiology and biotechnology , mutant , ouabain , biology , hypoxanthine , cell culture , cytotoxicity , dna synthesis , mutagen , dna replication , chinese hamster , dna , chemistry , biochemistry , in vitro , gene , genetics , cell growth , enzyme , organic chemistry , sodium
The cytotoxic and mutagenic effects of a direct perturbation of DNA during various portions of the DNA synthetic period (S phase) of a chemically induced, transformed line (Hut‐11A cells) derived from diploid human skin fibroblasts were examined. The cells were synchronized by a period of growth in low serum with a subsequent blockage of the cells at the G1/S boundary by hydroxyurea. This method resulted in over 90% synchrony, although approximately 20% of the cells were noncycling. Synchronized cells were treated for each of four 2‐h periods during the S phase with 5‐bromodeoxyuridine (BrdU) followed by irradiation with near‐ultraviolet (UV). The BrdU‐plus‐irradiation treatment was cytotoxic and mutagenic, while treatment with BrdU alone or irradiation alone was neither cytotoxic nor mutagenic. The cytotoxicity was dependent upon the periods of S phase during which treatment was administered. The highest lethality was observed for treatment in early to middle S phase, particularly in the first 2 h of S phase, whereas scare lethality was observed in late S phase. The BrdU‐plus‐irradiation treatment induced ouabain‐ and 6‐thioguanine‐resistant mutants, while BrdU alone or irradiation alone was not mutagenic. Ouabain‐resistant mutants were induced during early S phase by the BrdU‐plus‐irradiation treatment. 6‐Thioguanine‐resistant mutants, however, were induced during middle to late S phase. These results suggest that a certain region or regions in the DNA of Hut‐11A cells, as designated by their specific temporal relationship in the S phase, may be more sensitive to the DNA perturbation by BrdU treatment plus near‐UV irradiation for cell survival and that gene(s) responsible for Na + /K + ATPase is replicated during early S phase and gene(s) for hypoxanthine phosphoribosyl transferase is replicated during middle to late S phase.