Co-mutation of histone H2AX S139A with Y142A rescues Y142A-induced ionising radiation sensitivity

Under normal conditions histone H2AX is constitutively phosphorylated on tyrosine (Y) 142 by Williams–Beuren syndrome transcription factor kinase (WSTF). Following DNA double strand breaks (DSB), Y142 is de-phosphorylated and serine (S) 139 is phosphorylated. Here we explored DSB-dependent cross talk between H2AX residues S139 and Y142. H2axY142A mutation resulted in increased sensitivity to ionising radiation (IR), compared to H2axS139A. Interestingly, co-mutation of S139A and Y142A rescued IR sensitivity. The DSB response proteins 53Bp1 and Rad51 were recruited to IR-induced foci (IRIF) in H2axS139A, H2axY142A and H2axS139A/Y142A cells. Our results suggest that H2axY142A IR sensitivity is dependent upon the C-terminal residue, S139.

▸ H2AX-Y142A cells display a slow growth phenotype. ▸ We report H2AX-Y142A cells have increased constitutive cell death. ▸ We found that cells expressing H2AX-Y142A are IR sensitive. ▸ Combining H2AX mutations Y142A and S139A rescues the Y142A IR sensitivity. ▸ H2AX-Y142A cells can recruit the DNA repair proteins 53BP1 and Rad51.