Abstract
Histone mRNA decay (HD) is the process which ensures that histone mRNA is rapidly degraded following completion of DNA replication at the end of S-phase. Strict coordination between histone protein production and DNA replication is essential for the correct packaging of newly replicated DNA, as imbalances can lead to deleterious effects such as genomic instability. Interestingly, histone mRNA stability is controlled by the presence of a stem-loop structure at the 3' end of histone mRNA, and a protein, HBP/SLBP (hairpin/stem loop binding protein) which specifically binds to this structure, plays a major role in histone mRNA metabolism. Importantly, previous studies have shown HD is also one functional target of an intra S-phase checkpoint activated when DNA synthesis is inhibited, ensuring that histone mRNA is rapidly destroyed when global DNA replication is blocked. Consistent with this, replication stress-induced histone mRNA decay is blocked in the presence of inhibitors of the PIKK family of checkpoint protein kinases, implicating PIKK family members in the regulation of this process. Therefore, we aim to utilise a proteomic approach to to identify HBP/SLBP-associated proteins and post-translational status in order to elucidate the detailed mechanism of checkpoint activated HD. We have established isogenic cell lines stably expressing functional, tagged HBP/SLBP by using the Flp-InTM T-RexTM Expression system. Our results indicate that isogenic Flp-In HeLa cell lines inducibly expressing tagged forms of SLBP under the control of a doxycycline promoter are a useful model system for the molecular analysis of SLBP function during replication stress.
Published Version
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