Establishment of SV40-tsA58 transgenic rats as a source of conditionally immortalized cell lines

To isolate a variety of rat cell lines with differentiated functions, we es tablished transgenic rat lines expressing the temperature-sensitive large T -antigen of simian virus 40 (SV40) tsA58 mutant under the control of the SV 40 large T-antigen itself. We microinjected the DNA into 564 eggs of Wistar rat and 23 independent transgenic candidates were obtained. Ten pups died before weaning and eight transgenic rats could not transmit the transgene t o the progeny. Finally, five lines of the transgenic rat were established. Although one line (#1511-6) had low reproductivity, the other four lines re produced normally. Three out of the four lines (#1507-2, #1509-7 #1519-8) a ppeared normal but the other line had tumors in the brain and subcutaneous tissue at 3 weeks of age (#1511-6), and in the kidneys and subcutaneous tis sue at 18 to Ig-weeks of age (#1507-5). Fibroblast cells prepared from tran sgenic fetuses of lines #1507-5 and #1519-8 expressed the transgene and exh ibited temperature-dependent growth. Both of the lines (#1507-5 and #1519-8 ) were successfully generated to be homozygous by sibling mating of transge nic offspring. These transgenic rat lines have bred through many generation s and have been established to be a ready source of novel conditionally imm ortalized cell lines.