Biology subjects

Opresko, P. L.

Publications and source records attributed to Opresko, P. L..

3 recordsLinked to original sources

bioRxiv2023

OGG1 and MUTYH repair activities promote telomeric 8-oxoguanine induced cellular senescence

Telomeres are prone to formation of the common oxidative lesion 8-oxoguanine (8oxoG), and the acute production of 8oxoG damage at telomeres is sufficient to drive rapid cellular senescence. OGG1 and MUTYH glycosylases initiate base excision repair (BER) at 8oxoG sites to remove the lesion or prevent mutation. Here, we show OGG1 loss or inhibition, or MUTYH loss, partially rescues telomeric 8oxoG-induced senescence, and loss of both glycosylases results in a near complete rescue. Loss of these glycosylases also suppresses 8oxoG-induced telomere fragility and dysfunction, indicating that single-stranded break (SSB) intermediates arising downstream of glycosylase activity impair telomere replication. The failure to initiate BER in glycosylase-deficient cells suppresses PARylation at SSB intermediates and confers resistance to the synergistic effects of PARP inhibitors on damage-induced senescence. Our studies reveal that inefficient completion of 8oxoG BER at telomeres triggers cellular senescence via SSB intermediates which impair telomere replication and stability.

molecular biology↗

bioRxiv2022

Nanofluidic Device for Manipulation and Modification of DNA by Proteins

Single-molecule techniques provide important details supplementing the framework obtained from traditional bulk experiments. Many cellular processes such as DNA replication, DNA repair, and telomere maintenance involve interaction among multiple proteins, their co-factors, and DNA. To investigate such interactions and to differentiate the function of each component necessitate a technique that allows the combinatorial exposure of DNA to multiple proteins and co-factors as well as manipulation of the DNA configuration. We present a nanofluidic device with the capability of active combinatorial exchange of up to three buffers in real-time and dynamic manipulation of DNA under physiologically relevant conditions. We demonstrate its utility in monitoring compaction of DNA by telomeric proteins, DNA modification by an endonuclease, and DNA loop extrusion by cohesin.

biophysics↗

bioRxiv2021

Telomeric 8-oxoguanine drives rapid premature senescence in the absence of telomere shortening

Oxidative stress is a primary cause of cellular senescence and contributes to the pathogenesis of numerous human diseases. Oxidative damage to telomeric DNA is proposed to trigger premature senescence by accelerating telomere shortening. Here we tested this model directly using a precision tool to produce the common base lesion 8-oxo-guanine (8oxoG) exclusively at telomeres in human fibroblast and epithelial cells. A single induction of telomeric 8oxoG is sufficient to trigger multiple hallmarks of p53-dependent senescence. Telomeric 8oxoG activates ATM and ATR signaling, and enriches for markers of telomere dysfunction in replicating, but not quiescent cells. Acute 8oxoG production fails to shorten telomeres, but rather generates fragile sites and delayed mitotic DNA synthesis at telomeres, indicative of impaired replication. Based on our results we propose that oxidative stress promotes rapid senescence by producing oxidative base lesions which drive replication-dependent telomere fragility and dysfunction in the absence of shortening and shelterin loss.

molecular biology↗