An essential decision that germline stem cells must make is to proliferate mitotically or initiate meiotic development/gametogenesis. Disruption of this developmental switch can result in infertility and in some cases germline tumors. The C. elegans adult hermaphrodite is an important model for understanding control of the switch from germline stem cell fate to meiotic development/gametogenesis, where an outline of the process is emerging. Niche dependent GLP-1 Notch signaling promotes the stem cell fate and represses three redundant pathways that promote meiotic development/gametogenesis: the GLD-1 pathway (which represses expression of proliferation genes), the GLD-2 pathway (which promotes expression of meiotic genes), and a 3rd pathway whose existence has been revealed through genetic analysis but no gene products have been identified to date. At a cellular level, we have recently shown that the stem cell population is large and germ cells enter meiosis directly, without intervening transit-amplifying divisions. The absence of transit-amplifying divisions simplifies the analysis allowing straightforward assays to identify genes involved in repressing meiosis in stem cells and repressing proliferation at meiotic entry and is the primary reason why C. elegans is the major animal model for studying this important developmental switch. This proposal addresses three major areas in the stem cell - meiotic development/gametogenesis switch where there are large gaps in our knowledge. First, the transcriptional targets of GLP-1 signaling that promote the stem cell fate and/or repress the meiotic entry pathways are incompletely known. We propose to identify GLP-1 transcriptional targets and determine which meiotic entry pathway(s) they inhibit. Second, genes that constitute the 3rd meiotic entry pathway are unknown. Our preliminary results indicate that the SCFprom-1 ubiquitin mediated degradation complex is the 3rd pathway and we propose experiments to further test this hypothesis. Third, gld-1 mRNA translation/stability regulation is a central part of germline stem cell differentiation as expression must be repressed in stem cells and activated for meiosis; however control of GLD-1 accumulation is incompletely understood. We propose to (i) determine the mechanism of how two known GLP-1 transcriptional targets repress GLD-1 accumulation, (ii) determine the spatial and quantitative contribution of newly identified regulators of the germline stem cell differentiation in control of GLD-1 accumulation, and (iii) identify new regulators, since known regulators explain only part of the GLD-1 accumulation pattern, as a route to identify additional genes that control the developmental switch.

Public Health Relevance

The proposed research investigates the stem cell versus differentiation decision, which is an essential part of animal development and adult tissue homeostasis. Disruption of the decision can cause stem cell loss, resulting in tissue dysfunction - including sterility, and can lead to cancer.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM100756-07
Application #
9492570
Study Section
Cellular, Molecular and Integrative Reproduction Study Section (CMIR)
Program Officer
Salazar, Desiree Lynn
Project Start
2012-02-01
Project End
2020-05-31
Budget Start
2018-06-01
Budget End
2019-05-31
Support Year
7
Fiscal Year
2018
Total Cost
Indirect Cost
Name
Washington University
Department
Genetics
Type
Schools of Medicine
DUNS #
068552207
City
Saint Louis
State
MO
Country
United States
Zip Code
63130
Mohammad, Ariz; Vanden Broek, Kara; Wang, Christopher et al. (2018) Initiation of Meiotic Development Is Controlled by Three Post-transcriptional Pathways in Caenorhabditis elegans. Genetics 209:1197-1224
Kocsisova, Zuzana; Kornfeld, Kerry; Schedl, Tim (2018) Cell cycle accumulation of the proliferating cell nuclear antigen PCN-1 transitions from continuous in the adult germline to intermittent in the early embryo of C. elegans. BMC Dev Biol 18:12
Brenner, John L; Schedl, Tim (2016) Indirect Immunofluorescence of Proteins in Oogenic Germ Cells of Caenorhabditis elegans. Methods Mol Biol 1457:9-17
Brenner, John L; Schedl, Tim (2016) Germline Stem Cell Differentiation Entails Regional Control of Cell Fate Regulator GLD-1 in Caenorhabditis elegans. Genetics 202:1085-103
Rastogi, Suchita; Borgo, Ben; Pazdernik, Nanette et al. (2015) Caenorhabditis elegans glp-4 Encodes a Valyl Aminoacyl tRNA Synthetase. G3 (Bethesda) 5:2719-28
Zhang, Liang; Han, Longsen; Ma, Rujun et al. (2015) Sirt3 prevents maternal obesity-associated oxidative stress and meiotic defects in mouse oocytes. Cell Cycle 14:2959-68
Fox, Paul M; Schedl, Tim (2015) Analysis of Germline Stem Cell Differentiation Following Loss of GLP-1 Notch Activity in Caenorhabditis elegans. Genetics 201:167-84
Hou, Xiaojing; Zhang, Liang; Han, Longsen et al. (2015) Differing roles of pyruvate dehydrogenase kinases during mouse oocyte maturation. J Cell Sci 128:2319-29
Zhang, Liang; Hou, Xiaojing; Ma, Rujun et al. (2014) Sirt2 functions in spindle organization and chromosome alignment in mouse oocyte meiosis. FASEB J 28:1435-45
Ma, Rujun; Hou, Xiaojing; Zhang, Liang et al. (2014) Rab5a is required for spindle length control and kinetochore-microtubule attachment during meiosis in oocytes. FASEB J 28:4026-35

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