From G1 to S : understanding cell-cycle entry through single-cell microscopy techniques
Abstract/Contents
- Abstract
- Tight regulation of the cell cycle is critical for development and tissue homeostasis, and misregulation can lead to development defect, cancer, and degenerative diseases. While most of the individual components have been mapped out, our knowledge of the cell cycle remains incomplete. This is in part due to the popularity of bulk-cell assays in classical studies, where timing and kinetic measurements can be obscured by heterogeneity on a population level. In this thesis, we present two studies that take advantage of live, single-cell microscopy techniques. In the first study, we reveal how cells can proliferate without the kinase cyclin D-CDK4/6, a common target for cancer therapy. We found that in the start of this "alternate" pathway, the ordering of two critical events is inverted. We further demonstrate that in mice small intestinal crypt cells, this inverted sequence of events can be found alongside the canonical pathway that relies on cyclin D-CDK4/6. Our data thus suggests that wild-type, non-cancer cells can use two different paths to start the cell cycle. In the second study, we demonstrate how unperturbed cells use the kinase ATR, which detects DNA replication stress, to control CDK2 activity to rapidly modulate DNA synthesis rate. Besides fundamental characterizations, the two studies contribute to our understanding on how cells safeguard DNA replication. Cells need to achieve irreversibility prior to starting S phase to prevent reversion back to G1 (reversion results in over-replicated DNA). Once started, cells also must faithfully complete DNA replication. In the first study, we demonstrate that without CDK4/6 activity, cells have a different point of no return due to the inversion of signaling events. In the second study, we demonstrate that inevitable replication stress slows down DNA synthesis rate via an ATR-mediated negative feedback loop, thus preventing further accumulation of stress. Both studies enhance our knowledge on how cells maintain genome integrity. The studies also have potential clinical implications. An alternate pathway can at least partially explain how patients tolerate CDK4/6 inhibitors, and also explain how cancer cells bypass CDK4/6 inhibition. Finally, since many cancers have increased replication stress, understanding how cells resolve this stress may reveal synthetic lethal vulnerabilities in the future.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2019; ©2019 |
| Publication date | 2019; 2019 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Liu, Jinchin |
|---|---|
| Degree supervisor | Meyer, Tobias |
| Thesis advisor | Meyer, Tobias |
| Thesis advisor | Cimprich, Karlene |
| Thesis advisor | Ferrell, James Ellsworth |
| Degree committee member | Cimprich, Karlene |
| Degree committee member | Ferrell, James Ellsworth |
| Associated with | Stanford University, Department of Chemical and Systems Biology. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Jinchin (Chad) Liu. |
|---|---|
| Note | Submitted to the Department of Chemical and Systems Biology. |
| Thesis | Thesis Ph.D. Stanford University 2019. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2019 by Jinchin Liu
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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