TEMPERATURE STRESS SIGNALS ALERT and ALTER CELL SURVIVAL IN DNA REPLICATION DEFICIENT MUTANTS

Candidate: Venezia Benvenuto
Supervisor: Dr. Sarah Sabatinos

Abstract:

Cell cycle checkpoint mechanisms ensure cellular viability and genome stability. Without these checkpoints, mutations accumulate, resulting in the development of conditions such as cancer. During S-phase, the DNA replication checkpoint promotes cell survival through the employment of mechanisms which preserve the molecular machinery during DNA replication under stressinduced instability. Replication stress refers to events that slow or stall DNA replication. We use fission yeast, Schizosaccharomyces pombe, to investigate DNA replication checkpoint function during chemotherapy. Previous work in the Sabatinos lab has found that environmental stress alters DNA replication checkpoint response to replication-inhibiting drugs. For example, the drug, hydroxyurea depletes dNTPs; it is survivable in the presence of the DNA replication checkpoint, but cells lacking the checkpoint die. However, pre-treatment of cells with environmental stress appears to condition cells, improving survival in hydroxyurea. Specifically, the replication checkpoint mutant cells now survive in hydroxyurea. The largest effect is seen following temperature shock. Response to temperature initiates upregulation of genes as part of either a core or specific environmental stress response (CESR and SESR), which are controlled by separate pathways; the mitogen activated protein kinase (MAPK) pathway and stress activated protein kinase (SAPK) pathway. My work examines how timing of temperature response alters cells and permits survival in checkpoint-deficient cells. Ultimately, my project is designed to investigate how environmental stress responses intersect with the DNA replication checkpoint. Understanding this interaction may suggest new potential therapeutic targets in cancer chemotherapy.