Abstract
Purpose :
Parthanatos is a caspase-independent cell death pathway whose contributions to retinal tissue destruction during the progression of AIDS-related human cytomegalovirus retinitis have yet to be explored. We have previously shown that key parthanatos proteins are stimulated within MCMV-infected eyes of retinitis-susceptible mice with MAIDS of 10-weeks duration (MAIDS-10) (Oh et al, J Med Virol, 2019) but not within MCMV-infected eyes of retinitis-resistant mice with MAIDS of 4-weeks duration (MAIDS-4) (unpublished data). That stimulation of parthantos during MCMV-related MCMV retinitis might be cell-type specific prompted us to perform a pilot study to test this hypothesis using mouse embryo fibroblasts (MEF) and mouse lung fibroblasts (MLg), both non-ocular cells known to be susceptible to MCMV infection.
Methods :
Monolayers of MEF and MLg were inoculated with MCMV (moi = 1) or maintenance medium (control). Cell lysates of MCMV-infected and mock-infected cells were harvested at 24, 36, and 72 hrs after infection and subjected to western blot analysis for detection of parthantos-associated PARP-1, PAR, and PARG proteins.
Results :
Whereas MCMV-infected MEF showed stimulation of PAR and PARG when compared with mock-infected cells, stimulation of these two key parthanatos-associated proteins was not observed within MCMV-infected MLg at all times investigated. In comparison, PARP-1 protein showed significantly reduced stimulation within MCMV-infected MLg when compared with MCMV-infected MEF, but equivalent amounts of PARP-1 protein production were also observed within mock-infected MEF at all times investigated suggesting its stimulation was due to trauma associated with the inoculation procedure.
Conclusions :
Our findings support the hypothesis that stimulation of the parthantos cell death pathway during MCMV infection is cell-type specific. This proof-of-principle finding supports further investigations by us to determine if parthanatos operates within individual cell types of the retina during MAIDS-related MCMV retinitis with a focus on the retinal pigmented epithelium.
This is a 2021 ARVO Annual Meeting abstract.