Meiotic Checkpoint Activation Promotes Anaphase Promoting Complex/Cyclosome Substrate Specificity and UME6/SIN3/RPD3-Independent Reduction in EMG Expression

Author(s)

Rebecca Lewandowski

Date Approved

12-2014

Document Type

Dissertation

Degree Name

PhD in Cell and Molecular Biology

Department

Molecular Biology

College

Graduate School of Biomedical Sciences

First Advisor

Randy Strich, PhD

Committee Member 1

Katrina Cooper, PhD

Committee Member 2

Salvatore Caradonna, PhD

Committee Member 3

Dmitry Temiakov, PhD

Committee Member 4

Andrew Vershon, PhD

Subject(s)

Meiosis, Transcriptional Regulatory Elements, M Phase Cell Cycle Checkpoints, Yeasts

Disciplines

Cell Biology | Laboratory and Basic Science Research | Molecular Biology | Molecular Genetics

Abstract

Complex differentiation pathways, such as yeast meiosis and sporulation, are initiated in response to cell type and external stimuli and are driven by changes in tightly regulated and temporally expressed transcriptional programs. These programs are monitored by checkpoint mechanisms that couple meiotic progression to transcriptional activity to ensure each stage is successfully completed prior to progression into the next phase. This work investigated transcriptional regulation controlling meiotic progression when cells sense an insult to genetic integrity. These studies revealed that the early meiotic gene (EMG) repressor Ume6p is degraded during meiotic checkpoint activation triggered by the deoxyribonucleotide reductase inhibitor and replication checkpoint activator hydroxyurea (HU) in an APC/C^cdc20-dependent manner leading to reduced EMG levels despite Ume6p degradation. These data further show that the corepressor and histone deacetylase (HDAC) recruiter Sin3p is not required to maintain low EMG levels. Additionally, a hierarchy of APC/C^cdc20 substrate ordering is presented where the S phase B-type cyclin Clb5p and Ume6p are degraded during meiotic checkpoint activation but the separase inhibitor Pds1p is stabilized. Pds1p stabilization is also observed when the checkpoint signaling kinase and critical member of the checkpoint pathway CHK1 is deleted suggesting a meiosis-specific pathway protects Pds 1 p from degradation. This report finaIIy reveals that APC/C^cdc20-dependent Ume6p degradation, APC/C^cdc20 substrate ordering, and reduced EMG expression occur during recombination checkpoint activation when the RecA homolog and strand exchange enzyme DMC1 is deleted, triggering recombination checkpoint activation. Ultimately, these results indicate that the APC/C^cdc20 substrate specificity is regulated during checkpoint activation, and that a meiosis specific checkpoint system arrests meiotic progression through APC/C^cdc20 regulation and transcriptional activity.

Recommended Citation

Lewandowski, Rebecca, "Meiotic Checkpoint Activation Promotes Anaphase Promoting Complex/Cyclosome Substrate Specificity and UME6/SIN3/RPD3-Independent Reduction in EMG Expression" (2014). Graduate School of Biomedical Sciences Theses and Dissertations. 65.
https://rdw.rowan.edu/gsbs_etd/65