The human genome contains 11 APOBEC (apolipoprotein B mRNA editing catalytic 
polypeptide-like) cytidine deaminases classified into four families. These 
proteins function mainly in innate antiviral immunity and can also restrict 
endogenous retrotransposable element multiplication. The present study focuses 
on APOBEC3C (A3C), a member of the APOBEC3 subfamily. Some APOBEC3 proteins use 
their enzymatic activity on genomic DNA, inducing mutations and DNA damage, 
while other members facilitate DNA repair. Our results show that A3C is highly 
expressed in cells treated with DNA-damaging agents. Its expression is regulated 
by p53. Depletion of A3C slightly decreases proliferation and does not affect 
DNA repair via homologous recombination or nonhomologous end joining. The A3C 
interactomes obtained from control cells and cells exposed to the genotoxin 
etoposide indicated that A3C is a nucleolar protein. This was confirmed by the 
detection of either endogenous or ectopic A3C in nucleoli. Interestingly, we 
show that A3C is excluded from areas of DNA breaks in live cells. Our data also 
indicate that the C-terminal part of A3C is responsible for its nucleolar 
localization and exclusion from DNA damage sites.