Danilova, N., Bibikova, E., Covey, T.M., Nathanson, D., Dimitrova, E., Konto, Y., Lindgren, A., Glader, B., Radu, C.G., Sakamoto, K.M., Lin, S. (2014) The role of DNA damage response in zebrafish and cellular models of Diamond Blackfan Anemia. Disease models & mechanisms. 7(7):895-905.
Ribosomal biogenesis involves processing of pre-rRNA in assembly with ribosomal proteins (RPs). Deficiency of some RPs impairs processing and causes Diamond Blackfan Anemia (DBA) associated with anemia, congenital malformations, and cancer. p53 mediates many features of DBA but the mechanism of p53 activation remains unclear. Another hallmark of DBA is upregulation of adenosine deaminase (ADA) suggesting changes in nucleotide metabolism. In RP-deficient zebrafish, we found activation of both nucleotide catabolism and biosynthesis consistent with the need to break and replace the faulty rRNA. We also found upregulation of dNTP synthesis, a typical response to replication stress and DNA damage. Both RP-deficient zebrafish and human hematopoietic cells showed activation of the ATR/ATM/CHK1/2/p53 pathway. Other features of RP deficiency included an imbalanced dNTP pool, ATP depletion, and AMPK activation. Replication stress and DNA damage in cultured cells in non-DBA models can be decreased by exogenous nucleosides. Therefore, we treated RP-deficient zebrafish embryos with exogenous nucleosides and observed decreased activation of p53 and AMPK, reduced apoptosis, and rescue of hematopoiesis. Our data suggest that DNA damage response contributes to p53 activation in cellular and zebrafish models of DBA. Furthermore, rescue of RP-deficient zebrafish with exogenous nucleosides suggests that nucleoside supplements may be beneficial in DBA.