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Kirsanov O, Johnson TA, Niedenberger BA, Malachowski TN, Hale BJ, Chen Q, Lackford B, Wang J, Singh A, Schindler K, Hermann BP, Hu G, Geyer CB. Retinoic acid is dispensable for meiotic initiation but required for spermiogenesis in the mammalian testis. Development 2023; 150:dev201638. [PMID: 37350382 PMCID: PMC10357014 DOI: 10.1242/dev.201638] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 06/13/2023] [Indexed: 06/24/2023]
Abstract
Retinoic acid (RA) is the proposed mammalian 'meiosis inducing substance'. However, evidence for this role comes from studies in the fetal ovary, where germ cell differentiation and meiotic initiation are temporally inseparable. In the postnatal testis, these events are separated by more than 1 week. Exploiting this difference, we discovered that, although RA is required for spermatogonial differentiation, it is dispensable for the subsequent initiation, progression and completion of meiosis. Indeed, in the absence of RA, the meiotic transcriptome program in both differentiating spermatogonia and spermatocytes entering meiosis was largely unaffected. Instead, transcripts encoding factors required during spermiogenesis were aberrant during preleptonema, and the subsequent spermatid morphogenesis program was disrupted such that no sperm were produced. Taken together, these data reveal a RA-independent model for male meiotic initiation.
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Affiliation(s)
- Oleksandr Kirsanov
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27858, USA
| | - Taylor A. Johnson
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27858, USA
| | - Bryan A. Niedenberger
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27858, USA
| | - Taylor N. Malachowski
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27858, USA
| | - Benjamin J. Hale
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27858, USA
| | - Qing Chen
- Epigenetics and Stem Cell Laboratory, National Institute of Environmental Health Sciences, Durham, NC 27709, USA
| | - Brad Lackford
- Epigenetics and Stem Cell Laboratory, National Institute of Environmental Health Sciences, Durham, NC 27709, USA
| | - Jiajia Wang
- Epigenetics and Stem Cell Laboratory, National Institute of Environmental Health Sciences, Durham, NC 27709, USA
| | - Anukriti Singh
- Department of Neuroscience, Developmental and Regenerative Biology, The University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Karen Schindler
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Brian P. Hermann
- Department of Neuroscience, Developmental and Regenerative Biology, The University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Guang Hu
- Epigenetics and Stem Cell Laboratory, National Institute of Environmental Health Sciences, Durham, NC 27709, USA
| | - Christopher B. Geyer
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27858, USA
- East Carolina Diabetes and Obesity Institute at East Carolina University, Greenville, NC 27834, USA
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2
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Johnson TA, Niedenberger BA, Kirsanov O, Harrington EV, Malachowski T, Geyer CB. Differential responsiveness of spermatogonia to retinoic acid dictates precocious differentiation but not meiotic entry during steady-state spermatogenesis†. Biol Reprod 2023; 108:822-836. [PMID: 36708226 PMCID: PMC10183363 DOI: 10.1093/biolre/ioad010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 12/20/2022] [Accepted: 01/19/2023] [Indexed: 01/29/2023] Open
Abstract
The foundation of mammalian spermatogenesis is provided by undifferentiated spermatogonia, which comprise of spermatogonial stem cells (SSCs) and transit-amplifying progenitors that differentiate in response to retinoic acid (RA) and are committed to enter meiosis. Our laboratory recently reported that the foundational populations of SSCs, undifferentiated progenitors, and differentiating spermatogonia are formed in the neonatal testis in part based on their differential responsiveness to RA. Here, we expand on those findings to define the extent to which RA responsiveness during steady-state spermatogenesis in the adult testis regulates the spermatogonial fate. Our results reveal that both progenitor and differentiating spermatogonia throughout the testis are capable of responding to exogenous RA, but their resulting fates were quite distinct-undifferentiated progenitors precociously differentiated and proceeded into meiosis on a normal timeline, while differentiating spermatogonia were unable to hasten their entry into meiosis. This reveals that the spermatogonia responding to RA must still complete the 8.6 day differentiation program prior to their entry into meiosis. Addition of exogenous RA enriched testes with preleptotene and pachytene spermatocytes one and two seminiferous cycles later, respectively, supporting recent clinical studies reporting increased sperm production and enhanced fertility in subfertile men on long-term RA analog treatment. Collectively, our results reveal that a well-buffered system exists within mammalian testes to regulate spermatogonial RA exposure, that exposed undifferentiated progenitors can precociously differentiate, but must complete a normal-length differentiation program prior to entering meiosis, and that daily RA treatments increased the numbers of advanced germ cells by directing undifferentiated progenitors to continuously differentiate.
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Affiliation(s)
- Taylor A Johnson
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NCUSA
| | - Bryan A Niedenberger
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NCUSA
| | - Oleksandr Kirsanov
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NCUSA
| | - Ellen V Harrington
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NCUSA
| | - Taylor Malachowski
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NCUSA
| | - Christopher B Geyer
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NCUSA
- East Carolina Diabetes and Obesity Institute at East Carolina University, Greenville, NCUSA
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3
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Kirsanov O, Johnson T, Malachowski T, Niedenberger BA, Gilbert EA, Bhowmick D, Ozdinler PH, Gray DA, Fisher-Wellman K, Hermann BP, Geyer CB. Modeling mammalian spermatogonial differentiation and meiotic initiation in vitro. Development 2022; 149:282465. [PMID: 36250451 PMCID: PMC9845750 DOI: 10.1242/dev.200713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 10/10/2022] [Indexed: 11/06/2022]
Abstract
In mammalian testes, premeiotic spermatogonia respond to retinoic acid by completing an essential lengthy differentiation program before initiating meiosis. The molecular and cellular changes directing these developmental processes remain largely undefined. This wide gap in knowledge is due to two unresolved technical challenges: (1) lack of robust and reliable in vitro models to study differentiation and meiotic initiation; and (2) lack of methods to isolate large and pure populations of male germ cells at each stage of differentiation and at meiotic initiation. Here, we report a facile in vitro differentiation and meiotic initiation system that can be readily manipulated, including the use of chemical agents that cannot be safely administered to live animals. In addition, we present a transgenic mouse model enabling fluorescence-activated cell sorting-based isolation of millions of spermatogonia at specific developmental stages as well as meiotic spermatocytes.
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Affiliation(s)
- Oleksandr Kirsanov
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Taylor Johnson
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Taylor Malachowski
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Bryan A. Niedenberger
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Emma A. Gilbert
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Debajit Bhowmick
- Flow Cytometry Facility, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - P. Hande Ozdinler
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Evanston, IL 60611, USA
| | - Douglas A. Gray
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, K1H 8M5, Canada,Cancer Therapeutics, Ottawa Hospital Research Institute, Ottawa, K1H 8L6, Canada
| | - Kelsey Fisher-Wellman
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC 27858, USA,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA
| | - Brian P. Hermann
- Department of Neuroscience, Developmental and Regenerative Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Christopher B. Geyer
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27858, USA,Author for correspondence ()
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4
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Johnson TA, Kirsanov O, Niedenberger BA, Harrington E, Malachowski T, Geyer CB. Mammalian testes utilize multiple modalities to moderate spermatogonial responsiveness to retinoic acid. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.0r399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Taylor A. Johnson
- Anatomy & Cell BiologyBrody School of Medicine, East Carolina UniversityGreenvilleNC
| | - Oleksandr Kirsanov
- Anatomy & Cell BiologyBrody School of Medicine, East Carolina UniversityGreenvilleNC
| | - Bryan A. Niedenberger
- Anatomy & Cell BiologyBrody School of Medicine, East Carolina UniversityGreenvilleNC
| | - Ellen Harrington
- Anatomy & Cell BiologyBrody School of Medicine, East Carolina UniversityGreenvilleNC
| | - Taylor Malachowski
- Anatomy & Cell BiologyBrody School of Medicine, East Carolina UniversityGreenvilleNC
| | - Christopher B. Geyer
- Anatomy & Cell BiologyBrody School of Medicine, East Carolina UniversityGreenvilleNC
- Brody School of Medicine, East Carolina UniversityGreenvilleNC
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5
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Serra N, Velte EK, Niedenberger BA, Kirsanov O, Geyer CB. The mTORC1 component RPTOR is required for maintenance of the foundational spermatogonial stem cell pool in mice†. Biol Reprod 2020; 100:429-439. [PMID: 30202948 DOI: 10.1093/biolre/ioy198] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 08/06/2018] [Accepted: 09/07/2018] [Indexed: 01/15/2023] Open
Abstract
The self-renewal, proliferation, and differentiation of the spermatogonial populations must be finely coordinated in the mammalian testis, as dysregulation of these processes can lead to subfertility, infertility, or the formation of tumors. There are wide gaps in our understanding of how these spermatogonial populations are formed and maintained, and our laboratory has focused on identifying the molecular and cellular pathways that direct their development. Others and we have shown, using a combination of pharmacologic inhibitors and genetic models, that activation of mTOR complex 1 (mTORC1) is important for spermatogonial differentiation in vivo. Here, we extend those studies to directly test the germ cell-autonomous requirement for mTORC1 in spermatogonial differentiation. We created germ cell conditional knockout mice for "regulatory associated protein of MTOR, complex 1" (Rptor), which encodes an essential component of mTORC1. While germ cell KO mice were viable and healthy, they had smaller testes than littermate controls, and no sperm were present in their cauda epididymides. We found that an initial cohort of Rptor KO spermatogonia proliferated, differentiated, and entered meiosis (which they were unable to complete). However, no self-renewing spermatogonia were formed, and thus the entire germline was lost by adulthood, resulting in Sertoli cell-only testes. These results reveal the cell autonomous requirement for RPTOR in the formation or maintenance of the foundational self-renewing spermatogonial stem cell pool in the mouse testis and underscore complex roles for mTORC1 and its constituent proteins in male germ cell development.
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Affiliation(s)
- Nicholas Serra
- Department of Anatomy and Cell Biology, East Carolina University, Greenville, North Carolina, USA
| | - Ellen K Velte
- Department of Anatomy and Cell Biology, East Carolina University, Greenville, North Carolina, USA
| | - Bryan A Niedenberger
- Department of Anatomy and Cell Biology, East Carolina University, Greenville, North Carolina, USA
| | - Oleksander Kirsanov
- Department of Anatomy and Cell Biology, East Carolina University, Greenville, North Carolina, USA
| | - Christopher B Geyer
- Department of Anatomy and Cell Biology, East Carolina University, Greenville, North Carolina, USA.,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, USA
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6
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Hermann BP, Cheng K, Singh A, Roa-De La Cruz L, Mutoji KN, Chen IC, Gildersleeve H, Lehle JD, Mayo M, Westernströer B, Law NC, Oatley MJ, Velte EK, Niedenberger BA, Fritze D, Silber S, Geyer CB, Oatley JM, McCarrey JR. The Mammalian Spermatogenesis Single-Cell Transcriptome, from Spermatogonial Stem Cells to Spermatids. Cell Rep 2019; 25:1650-1667.e8. [PMID: 30404016 PMCID: PMC6384825 DOI: 10.1016/j.celrep.2018.10.026] [Citation(s) in RCA: 320] [Impact Index Per Article: 64.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 08/15/2018] [Accepted: 10/03/2018] [Indexed: 12/16/2022] Open
Abstract
Spermatogenesis is a complex and dynamic cellular differentiation process critical to male reproduction and sustained by spermatogonial stem cells (SSCs). Although patterns of gene expression have been described for aggregates of certain spermatogenic cell types, the full continuum of gene expression patterns underlying ongoing spermatogenesis in steady state was previously unclear. Here, we catalog single-cell transcriptomes for >62,000 individual spermatogenic cells from immature (postnatal day 6) and adult male mice and adult men. This allowed us to resolve SSC and progenitor spermatogonia, elucidate the full range of gene expression changes during male meiosis and spermiogenesis, and derive unique gene expression signatures for multiple mouse and human spermatogenic cell types and/or subtypes. These transcriptome datasets provide an information-rich resource for studies of SSCs, male meiosis, testicular cancer, male infertility, or contraceptive development, as well as a gene expression roadmap to be emulated in efforts to achieve spermatogenesis in vitro.
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Affiliation(s)
- Brian P Hermann
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA; Genomics Core, University of Texas at San Antonio, San Antonio, TX 78249, USA.
| | - Keren Cheng
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Anukriti Singh
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Lorena Roa-De La Cruz
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Kazadi N Mutoji
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - I-Chung Chen
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Heidi Gildersleeve
- Genomics Core, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Jake D Lehle
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Max Mayo
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Birgit Westernströer
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Nathan C Law
- Center for Reproductive Biology, School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99163, USA
| | - Melissa J Oatley
- Center for Reproductive Biology, School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99163, USA
| | - Ellen K Velte
- Department of Anatomy & Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27858, USA
| | - Bryan A Niedenberger
- Department of Anatomy & Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27858, USA
| | - Danielle Fritze
- The UT Transplant Center, UT Health San Antonio, San Antonio, TX 78229, USA
| | - Sherman Silber
- The Infertility Center of St. Louis, Chesterfield, MO 63017, USA
| | - Christopher B Geyer
- Department of Anatomy & Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27858, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834, USA
| | - Jon M Oatley
- Center for Reproductive Biology, School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99163, USA
| | - John R McCarrey
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA.
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7
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Velte EK, Niedenberger BA, Serra ND, Singh A, Roa-DeLaCruz L, Hermann BP, Geyer CB. Differential RA responsiveness directs formation of functionally distinct spermatogonial populations at the initiation of spermatogenesis in the mouse. Development 2019; 146:dev.173088. [PMID: 31023878 DOI: 10.1242/dev.173088] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 04/16/2019] [Indexed: 12/22/2022]
Abstract
In the mammalian testis, sustained spermatogenesis relies on spermatogonial stem cells (SSCs); their progeny either remain as stem cells (self-renewal) or proliferate and differentiate to enter meiosis in response to retinoic acid (RA). Here, we sought to uncover elusive mechanisms regulating a key switch fundamental to spermatogonial fate: the capacity of spermatogonia to respond to RA. Using the developing mouse testis as a model, we found that spermatogonia and precursor prospermatogonia exhibit a heterogeneous capacity to respond to RA with at least two underlying causes. First, progenitor spermatogonia are prevented from responding to RA by catabolic activity of cytochrome P450 family 26 enzymes. Second, a smaller subset of undifferentiated spermatogonia enriched for SSCs exhibit catabolism-independent RA insensitivity. Moreover, for the first time, we observed that precursor prospermatogonia are heterogeneous and comprise subpopulations that exhibit the same differential RA responsiveness found in neonatal spermatogonia. We propose a novel model by which mammalian prospermatogonial and spermatogonial fates are regulated by their intrinsic capacity to respond (or not) to the differentiation signal provided by RA before, and concurrent with, the initiation of spermatogenesis.
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Affiliation(s)
- Ellen K Velte
- Departments of Anatomy and Cell Biology, Brody School of Medicine, East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834, USA
| | - Bryan A Niedenberger
- Departments of Anatomy and Cell Biology, Brody School of Medicine, East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834, USA
| | - Nicholas D Serra
- Departments of Anatomy and Cell Biology, Brody School of Medicine, East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834, USA
| | - Anukriti Singh
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Lorena Roa-DeLaCruz
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Brian P Hermann
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Christopher B Geyer
- Departments of Anatomy and Cell Biology, Brody School of Medicine, East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834, USA .,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834, USA
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8
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Niedenberger BA, Cook K, Baena V, Serra ND, Velte EK, Agno JE, Litwa KA, Terasaki M, Hermann BP, Matzuk MM, Geyer CB. Dynamic cytoplasmic projections connect mammalian spermatogonia in vivo. Development 2018; 145:dev161323. [PMID: 29980567 PMCID: PMC6110146 DOI: 10.1242/dev.161323] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 06/27/2018] [Indexed: 01/12/2023]
Abstract
Throughout the male reproductive lifespan, spermatogonial stem cells (SSCs) produce committed progenitors that proliferate and then remain physically connected in growing clones via short cylindrical intercellular bridges (ICBs). These ICBs, which enlarge in meiotic spermatocytes, have been demonstrated to provide a conduit for postmeiotic haploid spermatids to share sex chromosome-derived gene products. In addition to ICBs, spermatogonia exhibit multiple thin cytoplasmic projections. Here, we have explored the nature of these projections in mice and find that they are dynamic, span considerable distances from their cell body (≥25 μm), either terminate or physically connect multiple adjacent spermatogonia, and allow for sharing of macromolecules. Our results extend the current model that subsets of spermatogonia exist as isolated cells or clones, and support a model in which spermatogonia of similar developmental fates are functionally connected through a shared dynamic cytoplasm mediated by thin cytoplasmic projections.
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Affiliation(s)
- Bryan A Niedenberger
- Department of Anatomy and Cell Biology at East Carolina University, Greenville, NC 27834, USA
| | - Kenneth Cook
- Department of Anatomy and Cell Biology at East Carolina University, Greenville, NC 27834, USA
| | - Valentina Baena
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Nicholas D Serra
- Department of Anatomy and Cell Biology at East Carolina University, Greenville, NC 27834, USA
| | - Ellen K Velte
- Department of Anatomy and Cell Biology at East Carolina University, Greenville, NC 27834, USA
| | - Julio E Agno
- Center for Drug Discovery and Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Karen A Litwa
- Department of Anatomy and Cell Biology at East Carolina University, Greenville, NC 27834, USA
| | - Mark Terasaki
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Brian P Hermann
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Martin M Matzuk
- Center for Drug Discovery and Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Christopher B Geyer
- Department of Anatomy and Cell Biology at East Carolina University, Greenville, NC 27834, USA
- East Carolina Diabetes and Obesity Institute at East Carolina University, Greenville, NC 27834, USA
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9
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Serra ND, Velte EK, Niedenberger BA, Kirsanov O, Geyer CB. Cell-autonomous requirement for mammalian target of rapamycin (Mtor) in spermatogonial proliferation and differentiation in the mouse†. Biol Reprod 2018; 96:816-828. [PMID: 28379293 DOI: 10.1093/biolre/iox022] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 03/28/2017] [Indexed: 12/11/2022] Open
Abstract
Spermatogonial stem cells must balance self-renewal with production of transit-amplifying progenitors that differentiate in response to retinoic acid (RA) before entering meiosis. This self-renewal vs. differentiation fate decision is critical for maintaining tissue homeostasis, as imbalances cause defects that can lead to human testicular cancer or infertility. Little is currently known about the program of differentiation initiated by RA, and the pathways and proteins involved are poorly defined. We recently found that RA stimulation of the Phosphatidylinositol 3-kinase (PI3K)/AKT/Mammalian target of rapamycin (mTOR) kinase signaling pathway is required for differentiation, and that short-term inhibition of mTOR complex 1 (mTORC1) by rapamycin blocked spermatogonial differentiation in vivo and prevented RA-induced translational activation. Since this phenotype resulted from global inhibition of mTORC1, we created conditional germ cell knockout mice to investigate the germ cell-autonomous role of MTOR in spermatogonial differentiation. MTOR germ cell KO mice were viable and healthy, but testes from neonatal (postnatal day (P)8), juvenile (P18), and adult (P > 60) KO mice were smaller than littermate controls, and no sperm were produced in adult testes. Histological and immunostaining analyses revealed that spermatogonial differentiation was blocked, and no spermatocytes were formed at any of the ages examined. Although spermatogonial proliferation was reduced in the neonatal testis, it was blocked altogether in the juvenile and adult testis. Importantly, a small population of self-renewing undifferentiated spermatogonia remained in adult testes. Taken together, these results reveal that MTOR is dispensable for the maintenance of undifferentiated spermatogonia, but is cell autonomously required for their proliferation and differentiation.
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Affiliation(s)
- Nicholas D Serra
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Ellen K Velte
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Bryan A Niedenberger
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Oleksander Kirsanov
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Christopher B Geyer
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA.,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, North Carolina, USA
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10
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Niedenberger BA, Geyer CB. Advanced immunostaining approaches to study early male germ cell development. Stem Cell Res 2018; 27:162-168. [PMID: 29475796 PMCID: PMC5894494 DOI: 10.1016/j.scr.2018.01.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 01/12/2018] [Accepted: 01/19/2018] [Indexed: 12/16/2022] Open
Abstract
Mammalian male germ cell development takes place in the testis under the influence of a variety of somatic cells and an incompletely defined paracrine and endocrine influences. Since it is not recapitulated well in vitro, researchers studying spermatogenesis often manipulate the germline by creating transgenic or knockout mice or by administering pharmaceutical agonists/antagonists or inhibitors. The effects of these types of manipulations on germline development can often be determined following microscopic imaging, both of stained and immunostained testis sections. Here, we describe approaches for microscopic analysis of the developing male germline, provide detailed protocols for a variety of immunostaining approaches, and discuss transgenic fluorescent reporter lines for studying the early stages of spermatogenesis.
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Affiliation(s)
- Bryan A Niedenberger
- East Carolina Diabetes and Obesity Institute East Carolina University, Greenville, NC, USA
| | - Christopher B Geyer
- East Carolina Diabetes and Obesity Institute East Carolina University, Greenville, NC, USA; Brody School of Medicine at East Carolina University, Greenville, NC, USA.
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11
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Busada JT, Velte EK, Serra N, Cook K, Niedenberger BA, Willis WD, Goulding EH, Eddy EM, Geyer CB. Rhox13 is required for a quantitatively normal first wave of spermatogenesis in mice. Reproduction 2016; 152:379-88. [PMID: 27486269 DOI: 10.1530/rep-16-0268] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 08/01/2016] [Indexed: 11/08/2022]
Abstract
We previously described a novel germ cell-specific X-linked reproductive homeobox gene (Rhox13) that is upregulated at the level of translation in response to retinoic acid (RA) in differentiating spermatogonia and preleptotene spermatocytes. We hypothesize that RHOX13 plays an essential role in male germ cell differentiation, and have tested this by creating a Rhox13 gene knockout (KO) mouse. Rhox13 KO mice are born in expected Mendelian ratios, and adults have slightly reduced testis weights, yet a full complement of spermatogenic cell types. Young KO mice (at ~7-8 weeks of age) have a ≈50% reduction in epididymal sperm counts, but numbers increased to WT levels as the mice reach ~17 weeks of age. Histological analysis of testes from juvenile KO mice reveals a number of defects during the first wave of spermatogenesis. These include increased apoptosis, delayed appearance of round spermatids and disruption of the precise stage-specific association of germ cells within the seminiferous tubules. Breeding studies reveal that both young and aged KO males produce normal-sized litters. Taken together, our results indicate that RHOX13 is not essential for mouse fertility in a controlled laboratory setting, but that it is required for optimal development of differentiating germ cells and progression of the first wave of spermatogenesis.
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Affiliation(s)
- Jonathan T Busada
- Department of Anatomy and Cell BiologyBrody School of Medicine at East Carolina University, Greenville, North Carolina, USA
| | - Ellen K Velte
- Department of Anatomy and Cell BiologyBrody School of Medicine at East Carolina University, Greenville, North Carolina, USA
| | - Nicholas Serra
- Department of Anatomy and Cell BiologyBrody School of Medicine at East Carolina University, Greenville, North Carolina, USA
| | - Kenneth Cook
- Department of Anatomy and Cell BiologyBrody School of Medicine at East Carolina University, Greenville, North Carolina, USA
| | - Bryan A Niedenberger
- Department of Anatomy and Cell BiologyBrody School of Medicine at East Carolina University, Greenville, North Carolina, USA
| | - William D Willis
- Gamete Biology GroupReproductive and Developmental Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - Eugenia H Goulding
- Gamete Biology GroupReproductive and Developmental Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - Edward M Eddy
- Gamete Biology GroupReproductive and Developmental Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - Christopher B Geyer
- Department of Anatomy and Cell BiologyBrody School of Medicine at East Carolina University, Greenville, North Carolina, USA East Carolina Diabetes and Obesity Institute Brody School of Medicine at East Carolina UniversityGreenville, North Carolina, USA
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12
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Abstract
Prospermatogonia transition to type A spermatogonia, which provide the source for the spermatogonial stem cell (SSC) pool. A percentage of these type A spermatogonia then differentiate to enter meiosis as spermatocytes by ∼P10. It is currently unclear as to when these distinct populations are initially formed in the neonatal testis, and when the expression of markers both characteristic of and required for the adult undifferentiated and differentiating states is established. In this study, we compared expression of known spermatogonial cell fate markers during normal development and in response to the differentiation signal provided by retinoic acid (RA). We found that some markers for the undifferentiated state (ZBTB16/PLZF and CDH1) were expressed in nearly all spermatogonia from P1 through P7. In contrast, differentiation markers (STRA8 and KIT) appeared in a subset of spermatogonia at P4, coincident with the onset of RA signaling. GFRA1, which was present in nearly all prospermatogonia at P1, was only retained in STRA8/KIT- spermatogonia. From P4 through P10, there was a great deal of heterogeneity in the male germ cell population in terms of expression of markers, as markers characteristic of the undifferentiated (except GFRA1) and differentiating states were co-expressed through this interval. After P10, these fate markers diverged to mark distinct populations of undifferentiated and differentiating spermatogonia, and this pattern was maintained in juvenile (P18) and adult (P>60) testes. Taken together, these results reveal that the spermatogonia population is heterogeneous during the first wave of spermatogenesis, and indicate that neonatal spermatogonia may not serve as an ideal substitute for studying the function of adult spermatogonia.
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Affiliation(s)
- Bryan A Niedenberger
- Department of Anatomy and Cell Biology Brody School of Medicine and East Carolina Diabetes and Obesity Institute East Carolina University, Greenville, North Carolina 27834, USA
| | - Jonathan T Busada
- Department of Anatomy and Cell Biology Brody School of Medicine and East Carolina Diabetes and Obesity Institute East Carolina University, Greenville, North Carolina 27834, USA
| | - Christopher B Geyer
- Department of Anatomy and Cell Biology Brody School of Medicine and East Carolina Diabetes and Obesity Institute East Carolina University, Greenville, North Carolina 27834, USA Department of Anatomy and Cell Biology Brody School of Medicine and East Carolina Diabetes and Obesity Institute East Carolina University, Greenville, North Carolina 27834, USA
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13
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Busada JT, Chappell VA, Niedenberger BA, Kaye EP, Keiper BD, Hogarth CA, Geyer CB. Retinoic acid regulates Kit translation during spermatogonial differentiation in the mouse. Dev Biol 2014; 397:140-9. [PMID: 25446031 DOI: 10.1016/j.ydbio.2014.10.020] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 10/22/2014] [Accepted: 10/23/2014] [Indexed: 01/12/2023]
Abstract
In the testis, a subset of spermatogonia retains stem cell potential, while others differentiate to eventually become spermatozoa. This delicate balance must be maintained, as defects can result in testicular cancer or infertility. Currently, little is known about the gene products and signaling pathways directing these critical cell fate decisions. Retinoic acid (RA) is a requisite driver of spermatogonial differentiation and entry into meiosis, yet the mechanisms activated downstream are undefined. Here, we determined a requirement for RA in the expression of KIT, a receptor tyrosine kinase essential for spermatogonial differentiation. We found that RA signaling utilized the PI3K/AKT/mTOR signaling pathway to induce the efficient translation of mRNAs for Kit, which are present but not translated in undifferentiated spermatogonia. Our findings provide an important molecular link between a morphogen (RA) and the expression of KIT protein, which together direct the differentiation of spermatogonia throughout the male reproductive lifespan.
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Affiliation(s)
- Jonathan T Busada
- Department of Anatomy and Cell Biology, Brody School of Medicine, Greenville, NC, USA
| | - Vesna A Chappell
- Department of Anatomy and Cell Biology, Brody School of Medicine, Greenville, NC, USA
| | - Bryan A Niedenberger
- Department of Anatomy and Cell Biology, Brody School of Medicine, Greenville, NC, USA
| | - Evelyn P Kaye
- Department of Anatomy and Cell Biology, Brody School of Medicine, Greenville, NC, USA
| | - Brett D Keiper
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, Greenville, NC, USA
| | - Cathryn A Hogarth
- Department of Molecular Biosciences and the Center for Reproductive Biology, Washington State University, Pullman, WA, USA
| | - Christopher B Geyer
- Department of Anatomy and Cell Biology, Brody School of Medicine, Greenville, NC, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA.
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14
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Niedenberger BA, Chappell VA, Otey CA, Geyer CB. Actin dynamics regulate subcellular localization of the F-actin-binding protein PALLD in mouse Sertoli cells. Reproduction 2014; 148:333-41. [PMID: 24989903 DOI: 10.1530/rep-14-0147] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Sertoli cells undergo terminal differentiation at puberty to support all phases of germ cell development, which occurs in the mouse beginning in the second week of life. By ∼18 days postpartum (dpp), nearly all Sertoli cells have ceased proliferation. This terminal differentiation is accompanied by the development of unique and regionally concentrated filamentous actin (F-actin) structures at the basal and apical aspects of the seminiferous epithelium, and this reorganization is likely to involve the action of actin-binding proteins. Palladin (PALLD) is a widely expressed F-actin-binding and bundling protein recently shown to regulate these structures, yet it is predominantly nuclear in Sertoli cells at puberty. We found that PALLD localized within nuclei of primary Sertoli cells grown in serum-free media but relocalized to the cytoplasm upon serum stimulation. We utilized this system with in vivo relevance to Sertoli cell development to investigate mechanisms regulating nuclear localization of this F-actin-binding protein. Our results indicate that PALLD can be shuttled from the nucleus to the cytoplasm, and that this relocalization occurred following depolymerization of the F-actin cytoskeleton in response to cAMP signaling. Nuclear localization was reduced in Hpg-mutant testes, suggesting the involvement of gonadotropin signaling. We found that PALLD nuclear localization was unaffected in testis tissues from LH receptor and androgen receptor-mutant mice. However, PALLD nuclear localization was reduced in the testes of FSH receptor-mutant mice, suggesting that FSH signaling during Sertoli cell maturation regulates this subcellular localization.
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MESH Headings
- Actin Cytoskeleton/metabolism
- Actins/metabolism
- Active Transport, Cell Nucleus
- Animals
- Cells, Cultured
- Cyclic AMP/metabolism
- Cytoplasm/metabolism
- Cytoskeletal Proteins/metabolism
- Follicle Stimulating Hormone/metabolism
- Gonadotropin-Releasing Hormone/genetics
- Gonadotropin-Releasing Hormone/metabolism
- Humans
- Karyopherins/metabolism
- Luteinizing Hormone/metabolism
- Male
- Mice
- Mice, Knockout
- Phosphoproteins/metabolism
- Protein Precursors/genetics
- Protein Precursors/metabolism
- Receptors, Androgen/genetics
- Receptors, Androgen/metabolism
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, FSH/genetics
- Receptors, FSH/metabolism
- Receptors, LH/genetics
- Receptors, LH/metabolism
- Sertoli Cells/metabolism
- rho GTP-Binding Proteins/metabolism
- Exportin 1 Protein
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Affiliation(s)
- Bryan A Niedenberger
- Department of Anatomy and Cell BiologyBrody School of Medicine, Greenville, North Carolina 27834, USAEast Carolina Diabetes and Obesity InstituteGreenville, North Carolina 27834, USADepartment of Cell Biology and PhysiologyUniversity of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Vesna A Chappell
- Department of Anatomy and Cell BiologyBrody School of Medicine, Greenville, North Carolina 27834, USAEast Carolina Diabetes and Obesity InstituteGreenville, North Carolina 27834, USADepartment of Cell Biology and PhysiologyUniversity of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Carol A Otey
- Department of Anatomy and Cell BiologyBrody School of Medicine, Greenville, North Carolina 27834, USAEast Carolina Diabetes and Obesity InstituteGreenville, North Carolina 27834, USADepartment of Cell Biology and PhysiologyUniversity of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Christopher B Geyer
- Department of Anatomy and Cell BiologyBrody School of Medicine, Greenville, North Carolina 27834, USAEast Carolina Diabetes and Obesity InstituteGreenville, North Carolina 27834, USADepartment of Cell Biology and PhysiologyUniversity of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA Department of Anatomy and Cell BiologyBrody School of Medicine, Greenville, North Carolina 27834, USAEast Carolina Diabetes and Obesity InstituteGreenville, North Carolina 27834, USADepartment of Cell Biology and PhysiologyUniversity of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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15
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Niedenberger BA, Chappell VK, Kaye EP, Renegar RH, Geyer CB. Nuclear localization of the actin regulatory protein palladin in sertoli cells. Mol Reprod Dev 2013; 80:403-13. [DOI: 10.1002/mrd.22174] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 03/19/2013] [Indexed: 12/13/2022]
Affiliation(s)
- Bryan A. Niedenberger
- Department of Anatomy and Cell Biology; Brody School of Medicine at East Carolina University; North Carolina
| | - Vesna K. Chappell
- Department of Anatomy and Cell Biology; Brody School of Medicine at East Carolina University; North Carolina
| | - Evelyn P. Kaye
- Department of Anatomy and Cell Biology; Brody School of Medicine at East Carolina University; North Carolina
| | - Randall H. Renegar
- Department of Anatomy and Cell Biology; Brody School of Medicine at East Carolina University; North Carolina
| | - Christopher B. Geyer
- Department of Anatomy and Cell Biology; Brody School of Medicine at East Carolina University; North Carolina
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16
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Geyer CB, Niedenberger BA, Chappell VK, Renegar RH. The Actin-Binding Protein Is Localized to Sertoli Cell Nuclei at Puberty. Biol Reprod 2011. [DOI: 10.1093/biolreprod/85.s1.416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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