Sexual reproduction requires the creation of haploid gametes from diploid cells. This two-fold reduction in chromosome number is carried out by a specialized, evolutionarily conserved, cell division called meiosis. In humans, failures in meiosis result in infertility and birth defects such as Trisomy 21 or Down syndrome. Unique to meiosis is the first meiotic division, in which homologous pairs of sister chromatids segregate to opposite poles. To promote proper orientation at Metaphase I of meiosis, homologous chromosomes are physically connected by a combination of sister chromatid cohesion and reciprocal crossovers. Crossovers result from meiotic recombination, which is initiated by double strand breaks (DSBs). Repair of these DSBs brings homologs together to form a structure called the synaptonemal complex (SC). Meiotic DSB repair is highly regulated to ensure that each homolog pair gets at least one crossover and that chromosome segregation is delayed until all DSBs have been repaired. An important element of this regulation in budding yeast involves phosphorylation by the meiosis-specific kinase, Mek1, as well as the conserved cell cycle kinases, CDK (cyclin-dependent kinase), DDK (Cdc7-Dbf4) and polo-like kinase (Cdc5). The goal of this grant is to understand how phosphorylation regulates meiotic recombination and chromosome synapsis.
The first aim tests a specific mechanistic hypothesis for how meiotic DSB repair is coordinated with meiotic progression through Mek1 phosphorylation of the meiosis-specific transcription factor, Ndt80.
The second aim addresses the role that phosphorylation of a conserved region of an SC protein called Zip1 plays in regulating in the crossover/noncrossover decision by enabling the creation of a specific class of crossovers that are distributed throughout the genome.
The third aim takes advantage of a major resource we developed in the last grant period?namely a dataset containing thousands of phosphorylated amino acids on proteins arrested in meiotic prophase. Phosphosites on proteins important for meiotic recombination and synapsis will be mutated and phenotypically characterized to discover the functional role of the phosphorylation. Two examples are provided for proteins we plan to pursue in the near future: Ecm11?a SUMOylated protein that is necessary for SC formation and Red1, whose degradation is mediated by Cdc5, resulting in SC disassembly and inactivation of Mek1 to allow repair of residual DSBs prior to the onset of the first meiotic division.

Public Health Relevance

Failures in the evolutionarily conserved cell division of meiosis result in infertility and birth defects such as Down syndrome. Proper meiotic chromosome segregation requires double strand break repair?a process also required to maintain genome integrity and prevent cancer. This grant is focused on understanding the molecular basis for proper chromosome behavior during meiosis?knowledge that may ultimately lead to the diagnosis and/or prevention of certain types of infertility, birth defects and even cancer.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM050717-25
Application #
9983747
Study Section
Molecular Genetics A Study Section (MGA)
Program Officer
Gindhart, Joseph G
Project Start
1995-01-01
Project End
2021-07-31
Budget Start
2020-08-01
Budget End
2021-07-31
Support Year
25
Fiscal Year
2020
Total Cost
Indirect Cost
Name
State University New York Stony Brook
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
804878247
City
Stony Brook
State
NY
Country
United States
Zip Code
11794
Kniewel, Ryan; Murakami, Hajime; Liu, Yan et al. (2017) Histone H3 Threonine 11 Phosphorylation Is Catalyzed Directly by the Meiosis-Specific Kinase Mek1 and Provides a Molecular Readout of Mek1 Activity in Vivo. Genetics 207:1313-1333
Prugar, Evelyn; Burnett, Cameron; Chen, Xiangyu et al. (2017) Coordination of Double Strand Break Repair and Meiotic Progression in Yeast by a Mek1-Ndt80 Negative Feedback Loop. Genetics 206:497-512
Callender, Tracy L; Laureau, Raphaelle; Wan, Lihong et al. (2016) Correction: Mek1 Down Regulates Rad51 Activity during Yeast Meiosis by Phosphorylation of Hed1. PLoS Genet 12:e1006283
Suhandynata, Raymond T; Wan, Lihong; Zhou, Huilin et al. (2016) Identification of Putative Mek1 Substrates during Meiosis in Saccharomyces cerevisiae Using Quantitative Phosphoproteomics. PLoS One 11:e0155931
Hollingsworth, Nancy M (2016) Mek1/Mre4 is a master regulator of meiotic recombination in budding yeast. Microb Cell 3:129-131
Callender, Tracy L; Laureau, Raphaelle; Wan, Lihong et al. (2016) Mek1 Down Regulates Rad51 Activity during Yeast Meiosis by Phosphorylation of Hed1. PLoS Genet 12:e1006226
Park, Jae-Sook; Thorsness, Mary K; Policastro, Robert et al. (2016) Yeast Vps13 promotes mitochondrial function and is localized at membrane contact sites. Mol Biol Cell 27:2435-49
Chen, Xiangyu; Suhandynata, Ray T; Sandhu, Rima et al. (2015) Phosphorylation of the Synaptonemal Complex Protein Zip1 Regulates the Crossover/Noncrossover Decision during Yeast Meiosis. PLoS Biol 13:e1002329
Suhandynata, Ray; Liang, Jason; Albuquerque, Claudio P et al. (2014) A method for sporulating budding yeast cells that allows for unbiased identification of kinase substrates using stable isotope labeling by amino acids in cell culture. G3 (Bethesda) 4:2125-35
Liu, Yan; Gaines, William A; Callender, Tracy et al. (2014) Down-regulation of Rad51 activity during meiosis in yeast prevents competition with Dmc1 for repair of double-strand breaks. PLoS Genet 10:e1004005

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