The long-term objective of the proposed research is to elucidate cellular and molecular controls of growth and differentiation in the animal germline. The proposed experiments address three fundamental problems of reproductive biology. First, how are germ cells controlled to continue mitosis or enter meiosis? Second, how are germ cells controlled to differentiate as sperm or oocyte in response to somatic cues? Third, how are the transitions from germline stem cell to transit-amplifying cell and then to meiotic entry controlled by the stem cell niche? Our proposed experiments focus on the C. elegans nematode germline, which is superbly poised to address these fundamental problems with molecular clarity. The power of this model derives from its experimental tractability and the rich foundation already laid. A single cell, the distal tip cell (DTC), creates the stem cell niche and germ cell fates are controlled by an emerging network of conserved molecular regulators, including GLP-1/Notch signaling, FBF/PUF and FOG-1/CPEB RNA-binding proteins, the GLD-2 cytoplasmic poly(A) polymerase and MPK- 1/MAP kinase, among others. Indeed, where known, the conserved regulators retain conserved regulatory relationships and biological functions. For example, PUF proteins control germline stem cells in nematodes, flies and probably humans, and PUF proteins control MAP kinase expression in both nematodes and humans.
Our specific aims will identify FBF target mRNAs and investigate conserved PUF controls of proliferation and differentiation;analyze the molecular mechanism by which FOG-1/CPEB controls both proliferation and differentiation in a dose-dependent manner;elucidate fog-3 regulation and investigate how FOG-3/Tob controls both proliferation and the sperm fate;investigate GLD-2 and its combinatorial control of germline fates;and investigate the Niche Region, the Transit Amplifying Compartment and their molecular regulation. The unifying theme is that the aims together will delineate how these conserved proteins work within a regulatory network to orchestrate germline growth and differentiation. Moreover, our studies promise to reveal general mechanisms that operate broadly in animal development, because of our focus on conserved regulators and their control of fundamental fate decisions. The elucidation of cellular and molecular controls of germline fate decisions will likely shed light on the mechanistic basis of germline cancers and infertility, two major health problems. Our studies may also impact use of germ cells as a potential source of stem cells for regenerative medicine.

Public Health Relevance

This proposal investigates the molecular regulation of germline stem cells, germline transit-amplifying cells and the sperm/oocyte decision. Regulators of these germline fates, when defective, cause cancer or infertility, two major health problems. Moreover, germ cells may well be the ultimate source of stem cells for regenerative medicine to replace tissues in diseased or injured individuals.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Cellular, Molecular and Integrative Reproduction Study Section (CMIR)
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Haynes, Susan R
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University of Wisconsin Madison
Schools of Earth Sciences/Natur
United States
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Prasad, Aman; Porter, Douglas F; Kroll-Conner, Peggy L et al. (2016) The PUF binding landscape in metazoan germ cells. RNA 22:1026-43
Noble, Daniel C; Aoki, Scott T; Ortiz, Marco A et al. (2016) Genomic Analyses of Sperm Fate Regulator Targets Reveal a Common Set of Oogenic mRNAs in Caenorhabditis elegans. Genetics 202:221-34
Friend, Kyle; Brooks, Hunter A; Propson, Nicholas E et al. (2015) Embryonic Stem Cell Growth Factors Regulate eIF2? Phosphorylation. PLoS One 10:e0139076
Byrd, Dana T; Knobel, Karla; Affeldt, Katharyn et al. (2014) A DTC niche plexus surrounds the germline stem cell pool in Caenorhabditis elegans. PLoS One 9:e88372
Sorokin, Elena P; Gasch, Audrey P; Kimble, Judith (2014) Competence for chemical reprogramming of sexual fate correlates with an intersexual molecular signature in Caenorhabditis elegans. Genetics 198:561-75
Kershner, Aaron M; Shin, Heaji; Hansen, Tyler J et al. (2014) Discovery of two GLP-1/Notch target genes that account for the role of GLP-1/Notch signaling in stem cell maintenance. Proc Natl Acad Sci U S A 111:3739-44
Ortiz, Marco A; Noble, Daniel; Sorokin, Elena P et al. (2014) A new dataset of spermatogenic vs. oogenic transcriptomes in the nematode Caenorhabditis elegans. G3 (Bethesda) 4:1765-72
Morgan, Clinton T; Noble, Daniel; Kimble, Judith (2013) Mitosis-meiosis and sperm-oocyte fate decisions are separable regulatory events. Proc Natl Acad Sci U S A 110:3411-6
Snow, J J; Lee, M-H; Verheyden, J et al. (2013) C. elegans FOG-3/Tob can either promote or inhibit germline proliferation, depending on gene dosage and genetic context. Oncogene 32:2614-21
Kershner, Aaron; Crittenden, Sarah L; Friend, Kyle et al. (2013) Germline stem cells and their regulation in the nematode Caenorhabditis elegans. Adv Exp Med Biol 786:29-46

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