Replication stress: mechanisms and molecules involved in dna replication progression and reinitiation
Year: 2019
Type: dissertation
Abstract: This thesis investigates the mechanisms that are activated in response to replication stress induced with hydroxyurea, an agent that causes deoxyribonucleotides depletion and arrest cells in S phase, in the non-transformed hTERT-RPE cells. The results obtained in the non- transformed cells are compared with the ones obtained with HCT116 colorectal cancer cells.\n\n\t\t\t\t Previous results indicated that, in response to an acute replication stress in hTERT-RPE, replication forks were able to restart without generating genomic instability, while in response to severe replication stress APC/CCdh1 was activated in S phase, which prevented the reinitiation of replication due to the inactivation of new origins.\n\n\t\t\t\t In this thesis we verified that, in response to an acute replication stress in hTERT-RPE cells, replication forks undergo fork remodelling, although CMG complexes maintain their integrity and can be reused to restart replication once replication stress is eliminated.\n\n\t\t\t\t In response to a prolonged replication stress, the lack of APC/CCdh1 activation in S phase in HCT116 tumour cells allows the resumption of replication by the activation of new origins, despite the acquisition of genomic instability during this process.\n\n\t\t\t\t The role of some proteins, RAD51 and OZF, in replication fork progression or restart during replication stress conditions is also examined. During a mild replication stress, RAD51 and OZF are important for replication fork progression in hTERT-RPE cells. At the same time, they are necessary for the correct progression of replication forks in HCT116 cells, which present a higher basal replication stress, even under unperturbed conditions. In response to an acute replication stress, RAD51 is also important for an efficient replication fork restart and progression in hTERT-RPE cells.\n\n\t\t\t\t Understanding the mechanisms that are working on non-transformed cells in replication stress, and comparing them with tumour cells, can help us to understand the alterations that tumour cells have acquired in order to bypass these regulations and to discover new molecules relevant to deal with replication stress.
Author: Sònia Feu i Coll
Language: English
Topic: DNA Repair Mechanisms
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W3001659961