Poster Presentation 44th Lorne Genome Conference 2023

Genome wide CRISPR screen identifies SAMHD1 and translation initiation factors, eIF4A1 and eIF4G1 as genes involved in the regulation of replication stress induced mitotic cell death (#106)

Aisling O'Connor 1 , Georgia R Kafer 2 , Christopher B Nelson 3 , Sienna Casolin 1 , Lucy French 1 , Harriet Gee 4 5 , Anthony J Cesare 1
  1. Genome Integrity Unit, CMRI, Westmead, NSW, Australia
  2. School of health and behavioural sciences , University of the Sunshine Coast, Moreton Bay, Queensland , Australia
  3. Telomere Length Regulation Unit, CMRI, Westmead, NSW, Australia
  4. CMRI, Westmead, NSW, Australia
  5. Sydney West Radiation Oncology Network , Australia

Mitotic catastrophe is a regulated mechanism that causes mitotic arrest and prevents the survival of cells that are unable to complete mitosis due to extensive DNA damage. This damage often arises due to replication stress. However, the underlying mechanisms of mitotic catastrophe are not clear. We carried out a positive selection, resistance, screen to identify genetic players involved in mediated replication stress induced mitotic cell death. We identified, SAMHD1, and the translation factors, eIF4A1, and eIF4G1 as mediators of mitotic cell death, and which cause resistance to mitotic cell death when mutated. SAMHD1, eIF4A1 and eIF4G1 prolong mitosis, drive cohesion fatigue leading to cell death. SAMHD1 functions in parallel with ATR and CHK1 kinases activities, while eIF4A1 functions independently of ATR and CHK1 kinases activities to drive mitotic cell death. Depletion of or genetic knockout of SAMHD1, eIF4A1 or eIF4G1 cause resistance to replication stress induced mitotic cell death. Our data indicates that SAMHD1, eIF4A1 and eIF4G1 are required to promote homologous recombination and double strand break formation upon lethal replication stress. This, we have revealed SAMHD1, eIF4A1 and eIF4G1 as critical mediators of mitotic cell death and highlight their potential roles in chemotherapeutic resistance.