Similarity in the molecular profile of mutations induced by UV light in shuttle vector plasmids propagated in mouse...

Shuttle vector plasmids pYZ289 were irradiated with UV and transfected to mouse cells to permit repair of damage, mutation and replication in the cells. The frequency and types of mutations were compared with those of UV-irradiated shuttle vector plasmids pZ189 which were propagated in normal human and xeroderma pigmentosum (XP) patient cells defective in DNA repair. Both shuttle vector plasmids contain a bacterial suppressor tRNA gene supF as a common mutation target. pYZ289 propagated in the mouse cells showed survival and mutation frequency similar to pZ189 propagated in the normal human cells. All single base substitution mutations were induced in dipyrimidine sequences and G:C to A:T transition was most frequently observed (47%) in the mouse cells; however, the frequency was significantly lower than that in the XP cells. The frequency of the base substitution mutations at A:T base pairs was significantly higher in the mouse cells (29%) than in the normal human (12%) and the XP cells (6%). These results show that similar types of mutations are induced by UV in mouse and normal human cells, and that the A:T base pair is relatively more mutable in mouse than in normal human and XP cells.