Immortalization of primary cells derived from the endangered Ryukyu long-furred rat.

The Ryukyu long-furred rat is an endangered species confined to the southernmost three small islands of Japan (Amami-Oshima, Tokunoshima, and Okinawa). Its population is rapidly decreasing because of roadkill, deforestation, and feral animals. To date, its genomic and biological information are poorly understood. In this study, we successfully immortalized Ryukyu long-furred rat cells by expressing a combination of cell cycle regulators, mutant cyclin-dependent kinase 4 (CDK4 R24C ) and cyclin D1, together with telomerase reverse transcriptase or an oncogenic protein, the Simian Virus large T antigen. The cell cycle distribution, telomerase enzymatic activity, and karyotype of these two immortalized cell lines were analyzed. The karyotype of the former cell line immortalized with cell cycle regulators and telomerase reverse transcriptase retained the nature of the primary cells, while that of the latter cell line immortalized with the Simian Virus large T antigen had many aberrant chromosomes. These immortalized cells would be valuable for studying the genomics and biology of Ryukyu long-furred rats.