Biology subjects

Blakemore, D.

Publications and source records attributed to Blakemore, D..

2 recordsLinked to original sources

bioRxiv2020

An ATM-MYBL2-CDC7 axis regulates replication initiation and prevents replication stress in pluripotent stem cells

Replication stress, a major cause of genome instability in cycling cells, is mainly prevented by the ATR-dependent replication stress response pathway in somatic cells. However, the replication stress response pathway in embryonic stem cells (ESCs) may be substantially different due to alterations in cell cycle phase length. The transcription factor MYBL2, which is implicated in cell cycle regulation, is expressed between hundred to thousand-fold more highly in ESCs compared to somatic cells. Here we show that MYBL2 functions to activate ATM and suppress replication stress in ESCs. Consequently, loss of MYBL2 or inhibition of ATM or Mre11 in ESCs, results in replication fork slowing, increased fork stalling and elevated origin firing. Additionally, we demonstrate that inhibition of CDC7 activity rescues replication stress induced by MYBL2 loss and ATM inhibition, suggesting that uncontrolled new origin firing may underlie the replication stress phenotype resulting from loss/inhibition of MYBL2 and ATM. Overall, this study proposes that in addition to ATR, a MYBL2-MRN-ATM replication stress response pathway functions in ESCs to control DNA replication initiation and prevent genome instability.

cell biology↗

bioRxiv2020

Ablation of MYB-dependent leukaemia phenotype in MLL-driven AML correlates with increased expression of MAFB.

The transcription factor MYB plays a pivotal role in haematopoietic homeostasis and its aberrant expression is involved in the genesis and maintenance of acute myeloid leukaemia (AML). Our previous work has demonstrated that not all AML types display the same dependency on MYB expression and that MYB dependence is dictated by the nature of the driver mutation. However, whether this difference in MYB dependency is a general trend in AML still remains to be further elucidated. In this study, we investigate the importance of MYB in human leukaemia by performing siRNA-mediated knock-down in cell line models of AML with different driver lesions. We show that the characteristic reduction in proliferation and the concomitant induction of myeloid differentiation that is observed in MLL-fusion-driven leukaemia upon MYB suppression is not seen in AML cells with a complex karyotype. By performing transcriptome analysis, we demonstrate that a strong activation of MAFB expression driven by MYB ablation is restricted to MYB-dependent cells. In line with these observations, stratification of publicly available patient data reveals a reciprocal relationship between the expression of MYB and MAFB, highlighting a novel connection between those two factors in AML.

cancer biology↗