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7 results on '"Sanford, Ethan James"'

1. Multi-step control of homologous recombination via Mec1/ATR suppresses chromosomal rearrangements

Author

Xie, Bokun, Sanford, Ethan James, Hung, Shih-Hsun, Wagner, Mateusz, Heyer, Wolf-Dietrich, and Smolka, Marcus B

Subjects
Biochemistry and Cell Biology, Biological Sciences, Genetics, Prevention, Human Genome, Saccharomyces cerevisiae Proteins, Saccharomyces cerevisiae, Protein Serine-Threonine Kinases, Homologous Recombination, Intracellular Signaling Peptides and Proteins, Cell Cycle Proteins, Checkpoint Kinase 2, RecQ Helicases, Signal Transduction, Phosphorylation, Chromosome Aberrations, Gene Rearrangement, Mec1, Sgs1, Resection, Chromosomal Rearrangement, Information and Computing Sciences, Medical and Health Sciences, Developmental Biology, Biological sciences, Biomedical and clinical sciences
Abstract

The Mec1/ATR kinase is crucial for genome stability, yet the mechanism by which it prevents gross chromosomal rearrangements (GCRs) remains unknown. Here we find that in cells with deficient Mec1 signaling, GCRs accumulate due to the deregulation of multiple steps in homologous recombination (HR). Mec1 primarily suppresses GCRs through its role in activating the canonical checkpoint kinase Rad53, which ensures the proper control of DNA end resection. Upon loss of Rad53 signaling and resection control, Mec1 becomes hyperactivated and triggers a salvage pathway in which the Sgs1 helicase is recruited to sites of DNA lesions via the 911-Dpb11 scaffolds and phosphorylated by Mec1 to favor heteroduplex rejection and limit HR-driven GCR accumulation. Fusing an ssDNA recognition domain to Sgs1 bypasses the requirement of Mec1 signaling for GCR suppression and nearly eliminates D-loop formation, thus preventing non-allelic recombination events. We propose that Mec1 regulates multiple steps of HR to prevent GCRs while ensuring balanced HR usage when needed for promoting tolerance to replication stress.

Published
2024

5. Separable roles for Mec1/ATR in genome maintenance, DNA replication, and checkpoint signaling

Author

Lanz, Michael Charles, Oberly, Susannah, Sanford, Ethan James, Sharma, Sushma, Chabes, Andrei, Smolka, Marcus Bustamante, Lanz, Michael Charles, Oberly, Susannah, Sanford, Ethan James, Sharma, Sushma, Chabes, Andrei, and Smolka, Marcus Bustamante

Abstract

The Mec1/ATR kinase coordinates multiple cellular responses to replication stress. In addition to its canonical role in activating the checkpoint kinase Rad53, Mec1 also plays checkpoint-independent roles in genome maintenance that are not well understood. Here we used a combined genetic-phosphoproteomic approach to manipulate Mec1 activation and globally monitor Mec1 signaling, allowing us to delineate distinct checkpoint-independent modes of Mec1 action. Using cells in which endogenous Mec1 activators were genetically ablated, we found that expression of "free" Mec1 activation domains (MADs) can robustly activate Mec1 and rescue the severe DNA replication and growth defects of these cells back to wild-type levels. However, unlike the activation mediated by endogenous activator proteins, "free" MADs are unable to stimulate Mec1-mediated suppression of gross chromosomal rearrangements (GCRs), revealing that Mec1's role in genome maintenance is separable from a previously unappreciated proreplicative function. Both Mec1's functions in promoting replication and suppressing GCRs are independent of the downstream checkpoint kinases. Additionally, Mec1-dependent GCR suppression seems to require localized Mec1 action at DNA lesions, which correlates with the phosphorylation of activator-proximal substrates involved in homologous recombination-mediated DNA repair. These findings establish that Mec1 initiates checkpoint signaling, promotes DNA replication, and maintains genetic stability through distinct modes of action.

Published
2018
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7. Multi-Step Control of Homologous Recombination by Mec1/ATR Ensures Robust Suppression of Gross Chromosomal Rearrangements.

Author

Xie B, Sanford EJ, Hung SH, Wagner MM, Heyer WD, and Smolka MB

Abstract

The Mec1/ATR kinase is crucial for genome stability, yet the mechanism by which it prevents gross chromosomal rearrangements (GCRs) remains unknown. Here we find that in cells with deficient Mec1 signaling, GCRs accumulate due to the deregulation of multiple steps in homologous recombination (HR). Mec1 primarily suppresses GCRs through its role in activating the canonical checkpoint kinase Rad53, which ensures the proper control of DNA end resection. Upon loss of Rad53 signaling and resection control, Mec1 becomes hyperactivated and triggers a salvage pathway in which the Sgs1 helicase is recruited to sites of DNA lesions via the 911-Dpb11 scaffolds to favor heteroduplex rejection and limit HR-driven GCR accumulation. Fusing an ssDNA recognition domain to Sgs1 bypasses the requirement of Mec1 signaling for GCR suppression and nearly eliminates D-loop formation, thus preventing non-allelic recombination events. We propose that Mec1 regulates multiple steps of HR to prevent GCRs while ensuring balanced HR usage when needed for promoting tolerance to replication stress.

Published
2023
Full Text
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