Mitochondrial deoxyguanosine kinase depletion induced ROS causes melanocyte stem cell exhaustion and hair greying

Hair pigmentation is regulated by melanocyte stem cells (MeSCs) within the hair follicle. Mitochondrial dysfunction is associated with hair depigmentation, primarily due to defects in melanogenesis. However, the mechanisms by which mitochondria support MeSCs during hair pigmentation remain obscure. In this study, we investigated the role of mitochondrial deoxyguanosine kinase (DGUOK), which provides guanosine and adenosine nucleotides for mitochondrial DNA (mtDNA) replication, in hair pigmentation and MeSCs maintenance. Dguok depleted and conditional knockout mice exhibit premature hair greying. This phenotype was not due to impaired melanin production by melanocytes but was associated with a significant loss of MeSCs and mature melanocytes. Notably, Dguok deficiency decreased the expression of 13 mtDNA-encoded genes, increased the levels of reactive oxygen species (ROS) and apoptosis in MeSCs. Treatment with N-acetylcysteine (NAC), an ROS inhibitor, effectively mitigated the depigmentation and rejuvenated the MeSCs population. These findings underscore the critical role of DGUOK in regulating mtDNA integrity, which is vital for sustaining MeSCs and ensuring hair pigmentation, providing valuable insights that may inform therapeutic strategies for combating hair greying.