Establishment of primary and immortalized fibroblasts reveals resistance to cytotoxic agents and loss of necroptosis-inducing ability in long-lived Damaraland mole-rats

The Damaraland mole-rat (DMR; Fukomys damarensis) is a long-lived (~ 20 years) Bathyergid rodent that diverged 26 million years ago from its close relative, the naked mole-rat (NMR). While the properties of NMR cultured fibroblasts have been extensively studied and have revealed several unusual features of this cancer-resistant, long-lived species, comparative DMR studies are extremely limited. We optimized conditions for successfully culturing primary DMR skin fibroblasts and also established immortalized DMR cells using simian virus 40 early region expression. Like NMRs, DMR fibroblasts are more resistant than mice to various cytotoxins including heavy metals, DNA-damaging agents, oxidative stressors, and proteasome inhibitors. DMR genome sequencing analyses revealed the presence of premature stop codons in the master regulator genes of necroptosis, an inflammatory programmed cell death-receptor-interacting protein kinase 3 (RIPK3) and mixed lineage kinase domain-like (MLKL), although these mutations have different locations to those found in the NMR. DMR cells, like NMR cells, did not show significantly increased cell death in response to necroptosis induction. Our data suggest that both Bathyergid species require species-specific cell culture conditions for optimized growth, display similar resistance to cytotoxins, and show loss-of-function mutations abrogating the ability to employ necroptosis. These shared traits may contribute to their evolved adaptations to their subterranean lifestyle and prolonged longevity. These convergent insights and valuable resource may be pertinent to biomedical research.