Abstract
BACKGROUND
Senescence of human dental pulp stem cells (DPSCs) weakens the differentiation and regeneration ability, affecting their function and the tooth, and limiting their in vitro application. Carnitine palmitoyltransferase 1A (CPT1A) has been reported to regulate the aging of multiple cells.
AIM
To investigate the effects of CPT1A on DPSC senescence and the underlying mechanism, particularly PTEN-induced kinase 1-mediated mitophagy.
METHODS
Human DPSCs at seven (p7) and 15 (p15) passages were used for functional analysis. Cell senescence and mitophagy were evaluated using senescence associated β-galactosidase staining and immunoblotting. The effect of CPT1A on Parkin succinylation was assessed using co-immunoprecipitation (co-IP)/IP, immunoblotting, and cycloheximide chase experiment. The aging mouse model was established using D-galactose (D-gal), and both senescence and mitophagy were evaluated in dental pulp tissues.
RESULTS
CPT1A expression was increased in DPSCs at p15. Compared with p7 cells, p15 cells had higher senescence and lower mitophagy levels, while knockdown of CPT1A inhibited senescence and promoted mitophagy of p15 DPSCs. Additionally, silencing CPT1A reduced the succinylation of Parkin at K27 site and enhanced Parkin protein stability. CPT1A succinylates Parkin and suppresses mitophagy through its lysine succinyltransferase activity. Moreover, the mitophagy inhibitor Mdivi-1 or knockdown of Parkin abrogated the effects on senescence and mitophagy mediated by CPT1A knockdown. The in vivo experiments showed that silencing CPT1A inhibits D-gal-induced dental pulp aging by promoting Parkin-mediated mitophagy.
CONCLUSION
Silencing of CPT1A suppresses senescence of DPSCs by facilitating mitophagy, which is associated with the inhibition of succinylation of Parkin, suggesting a new mechanism and target for DPSC aging.