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Park Y, Gaddy M, Hyun M, Jones ME, Aslam HM, Lee MH. Genetic and Chemical Controls of Sperm Fate and Spermatocyte Dedifferentiation via PUF-8 and MPK-1 in Caenorhabditis elegans. Cells 2023; 12:cells12030434. [PMID: 36766775 PMCID: PMC9913519 DOI: 10.3390/cells12030434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/21/2023] [Accepted: 01/24/2023] [Indexed: 02/03/2023] Open
Abstract
Using the nematode C. elegans germline as a model system, we previously reported that PUF-8 (a PUF RNA-binding protein) and LIP-1 (a dual-specificity phosphatase) repress sperm fate at 20 °C and the dedifferentiation of spermatocytes into mitotic cells (termed "spermatocyte dedifferentiation") at 25 °C. Thus, double mutants lacking both PUF-8 and LIP-1 produce excess sperm at 20 °C, and their spermatocytes return to mitotically dividing cells via dedifferentiation at 25 °C, resulting in germline tumors. To gain insight into the molecular competence for spermatocyte dedifferentiation, we compared the germline phenotypes of three mutant strains that produce excess sperm-fem-3(q20gf), puf-8(q725); fem-3(q20gf), and puf-8(q725); lip-1(zh15). Spermatocyte dedifferentiation was not observed in fem-3(q20gf) mutants, but it was more severe in puf-8(q725); lip-1(zh15) than in puf-8(q725); fem-3(q20gf) mutants. These results suggest that MPK-1 (the C. elegans ERK1/2 MAPK ortholog) activation in the absence of PUF-8 is required to promote spermatocyte dedifferentiation. This idea was confirmed using Resveratrol (RSV), a potential activator of MPK-1 and ERK1/2 in C. elegans and human cells, respectively. Notably, spermatocyte dedifferentiation was significantly enhanced by RSV treatment in the absence of PUF-8, and its effect was blocked by mpk-1 RNAi. We, therefore, conclude that PUF-8 and MPK-1 are essential regulators for spermatocyte dedifferentiation and tumorigenesis. Since these regulators are broadly conserved, we suggest that similar regulatory circuitry may control cellular dedifferentiation and tumorigenesis in other organisms, including humans.
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Affiliation(s)
- Youngyong Park
- Division of Hematology/Oncology, Department of Internal Medicine, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
| | - Matthew Gaddy
- Division of Hematology/Oncology, Department of Internal Medicine, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
| | - Moonjung Hyun
- Biological Resources Research Group, Bioenvironmental Science & Toxicology Division, Korea Institute of Toxicology, Jinju 52834, Gyeongsangnam-do, Republic of Korea
| | - Mariah E. Jones
- Division of Hematology/Oncology, Department of Internal Medicine, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
| | - Hafiz M. Aslam
- Division of Hematology/Oncology, Department of Internal Medicine, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
| | - Myon Hee Lee
- Division of Hematology/Oncology, Department of Internal Medicine, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
- Department of Biology, East Carolina University, Greenville, NC 27858, USA
- Correspondence:
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2
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Ellis RE. Sex Determination in Nematode Germ Cells. Sex Dev 2022:1-18. [PMID: 35172320 PMCID: PMC9378769 DOI: 10.1159/000520872] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 11/02/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Animal germ cells differentiate as sperm or as oocytes. These sexual fates are controlled by complex regulatory pathways to ensure that the proper gametes are made at the appropriate times. SUMMARY Nematodes like Caenorhabditis elegans and its close relatives are ideal models for studying how this regulation works, because the XX animals are self-fertile hermaphrodites that produce both sperm and oocytes. In these worms, germ cells use the same signal transduction pathway that functions in somatic cells. This pathway determines the activity of the transcription factor TRA-1, a Gli protein that can repress male genes. However, the pathway is extensively modified in germ cells, largely by the action of translational regulators like the PUF proteins. Many of these modifications play critical roles in allowing the XX hermaphrodites to make sperm in an otherwise female body. Finally, TRA-1 cooperates with chromatin regulators in the germ line to control the activity of fog-1 and fog-3, which are essential for spermatogenesis. FOG-1 and FOG-3 work together to determine germ cell fates by blocking the translation of oogenic transcripts. Key Messages: Although there is great diversity in how germ cell fates are controlled in other animals, many of the key nematode genes are conserved, and the critical role of translational regulators may be universal.
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Affiliation(s)
- Ronald E Ellis
- Department of Molecular Biology, Rowan University SOM, Stratford, New Jersey, USA
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3
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Maniates KA, Olson BS, Abbott AL. Sperm fate is promoted by the mir-44 microRNA family in the Caenorhabditis elegans hermaphrodite germline. Genetics 2021; 217:1-14. [PMID: 33683352 PMCID: PMC8045739 DOI: 10.1093/genetics/iyaa006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 11/12/2020] [Indexed: 11/12/2022] Open
Abstract
Posttranscriptional regulation of gene expression, typically effected by RNA-binding proteins, microRNAs (miRNAs), and translation initiation factors, is essential for normal germ cell function. Numerous miRNAs have been detected in the germline; however, the functions of specific miRNAs remain largely unknown. Functions of miRNAs have been difficult to determine as miRNAs often modestly repress target mRNAs and are suggested to sculpt or fine tune gene expression to allow for the robust expression of cell fates. In Caenorhabditis elegans hermaphrodites, cell fate decisions are made for germline sex determination during larval development when sperm are generated in a short window before the switch to oocyte production. Here, analysis of newly generated mir-44 family mutants has identified a family of miRNAs that modulate the germline sex determination pathway in C. elegans. Mutants with the loss of mir-44 and mir-45 produce fewer sperm, showing both a delay in the specification and formation of sperm as well as an early termination of sperm specification accompanied by a premature switch to oocyte production. mir-44 and mir-45 are necessary for the normal period of fog-1 expression in larval development. Through genetic analysis, we find that mir-44 and mir-45 may act upstream of fbf-1 and fem-3 to promote sperm specification. Our research indicates that the mir-44 family promotes sperm cell fate specification during larval development and identifies an additional posttranscriptional regulator of the germline sex determination pathway.
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Affiliation(s)
- Katherine A Maniates
- Department of Biological Sciences, Marquette University, 1428 W. Clybourn Ave, PO Box 1881, Milwaukee, WI 53233, USA
| | - Benjamin S Olson
- Department of Biological Sciences, Marquette University, 1428 W. Clybourn Ave, PO Box 1881, Milwaukee, WI 53233, USA
| | - Allison L Abbott
- Department of Biological Sciences, Marquette University, 1428 W. Clybourn Ave, PO Box 1881, Milwaukee, WI 53233, USA
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4
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Abstract
Primordial germ cells (PGCs) must complete a complex and dynamic developmental program during embryogenesis to establish the germline. This process is highly conserved and involves a diverse array of tasks required of PGCs, including migration, survival, sex differentiation, and extensive epigenetic reprogramming. A common theme across many organisms is that PGC success is heterogeneous: only a portion of all PGCs complete all these steps while many other PGCs are eliminated from further germline contribution. The differences that distinguish successful PGCs as a population are not well understood. Here, we examine variation that exists in PGCs as they navigate the many stages of this developmental journey. We explore potential sources of PGC heterogeneity and their potential implications in affecting germ cell behaviors. Lastly, we discuss the potential for PGC development to function as a multistage selection process that assesses heterogeneity in PGCs to refine germline quality.
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Affiliation(s)
- Daniel H Nguyen
- Department of Obstetrics, Gynecology and Reproductive Science, Center for Reproductive Sciences, Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research, University of California, San Francisco, CA, United States
| | - Rebecca G Jaszczak
- Department of Obstetrics, Gynecology and Reproductive Science, Center for Reproductive Sciences, Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research, University of California, San Francisco, CA, United States
| | - Diana J Laird
- Department of Obstetrics, Gynecology and Reproductive Science, Center for Reproductive Sciences, Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research, University of California, San Francisco, CA, United States.
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5
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Poush JA, Blouin NA, Di Bona KR, Lažetić V, Fay DS. Regulation of germ cell development by ARI1 family ubiquitin ligases in C. elegans. Sci Rep 2018; 8:17737. [PMID: 30531803 PMCID: PMC6288150 DOI: 10.1038/s41598-018-35691-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 11/09/2018] [Indexed: 11/25/2022] Open
Abstract
RING-between-RING (RBR) E3 ubiquitin ligases are implicated in various developmental processes, and mutations in genes encoding RBR proteins HHARI/ARIH1 and Parkin are associated with human diseases. Here we show by phylogenetic analysis that the ARI1 family has undergone a dramatic expansion within the Caenorhabditis clade in recent history, a characteristic shared by some genes involved in germline development. We then examined the effects of deleting all ARI1 family members in the nematode Caenorhabditis elegans, which to our knowledge represents the first complete knockout of ARI1 function in a metazoan. Hermaphrodites that lacked or had strongly reduced ARI1 activity had low fecundity and were partially defective in initiation of oocyte differentiation. We provide evidence that the C. elegans ARI1s likely function downstream or in parallel to FBF-1 and FBF-2, two closely related RNA-binding proteins that are required for the switch from spermatogenesis to oogenesis during late larval development. Previous studies have shown that the E2 enzymes UBC-18/UBCH7 and UBC-3/CDC34 can functionally collaborate with ARI1 family members. Our data indicated that UBC-18, but not UBC-3, specifically cooperates with the ARI1s in germline development. These findings provide new insights into the functions of RING-between-RING proteins and Ariadne E3s during development.
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Affiliation(s)
- Julian A Poush
- Department of Molecular Biology, College of Agriculture and Natural Resources, University of Wyoming, Laramie, WY, 82071, USA
| | - Nicolas A Blouin
- Department of Molecular Biology, College of Agriculture and Natural Resources, University of Wyoming, Laramie, WY, 82071, USA
- Wyoming INBRE Bioinformatics Core, Laramie, USA
| | - Kristin R Di Bona
- Department of Molecular Biology, College of Agriculture and Natural Resources, University of Wyoming, Laramie, WY, 82071, USA
| | - Vladimir Lažetić
- Department of Molecular Biology, College of Agriculture and Natural Resources, University of Wyoming, Laramie, WY, 82071, USA
| | - David S Fay
- Department of Molecular Biology, College of Agriculture and Natural Resources, University of Wyoming, Laramie, WY, 82071, USA.
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6
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MPK-1/ERK regulatory network controls the number of sperm by regulating timing of sperm-oocyte switch in C. elegans germline. Biochem Biophys Res Commun 2017; 491:1077-1082. [PMID: 28782521 DOI: 10.1016/j.bbrc.2017.08.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 08/02/2017] [Indexed: 11/21/2022]
Abstract
The precise regulation of germline sexual fate is crucial for animal fertility. In C. elegans, the production of either type of gamete, sperm or oocyte, becomes mutually exclusive beyond the larval stage. Hermaphrodites initially produce sperm and then switch to produce oocytes. This change of fate during germline development is tightly controlled by several regulators. In C. elegans hermaphrodites, FBF-1 and FBF-2 (>95% identical, members of the Pumilio RNA-binding protein family) proteins function redundantly to promote the sperm-oocyte switch. Here, we demonstrate that loss of LIP-1 (dual specificity phosphatase) in fbf-1(ok91) single mutants leads to excess sperm production due to a delayed sperm-oocyte switch. This phenotype was dramatically rescued by depletion of MPK-1 (an ERK homolog). In contrast, loss of LIP-1 in fbf-2(q738) single mutants leads to a premature sperm-oocyte switch and loss of sperm. Notably, fbf-1 fbf-2; lip-1 triple mutants produce excess sperm. These results suggest that the MPK-1/ERK regulatory network, including FBF-1, FBF-2, and LIP-1, controls the number of sperm by regulating the timing of the sperm-oocyte switch in C. elegans.
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7
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Cruz-Reyes J, Mooers BHM, Abu-Adas Z, Kumar V, Gulati S. DEAH-RHA helicase•Znf cofactor systems in kinetoplastid RNA editing and evolutionarily distant RNA processes. RNA & DISEASE 2016; 3. [PMID: 27540585 PMCID: PMC4987287 DOI: 10.14800/rd.1336] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Multi-zinc finger proteins are an emerging class of cofactors in DEAH-RHA RNA helicases across highly divergent eukaryotic lineages. DEAH-RHA helicase•zinc finger cofactor partnerships predate the split of kinetoplastid protozoa, which include several human pathogens, from other eukaryotic lineages 100-400 Ma. Despite a long evolutionary history, the prototypical DEAH-RHA domains remain highly conserved. This short review focuses on a recently identified DEAH-RHA helicase•zinc finger cofactor system in kinetoplastid RNA editing, and its potential functional parallels with analogous systems in embryogenesis control in nematodes and antivirus protection in humans.
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Affiliation(s)
- Jorge Cruz-Reyes
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Blaine H M Mooers
- Department of Biochemistry & Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Zakaria Abu-Adas
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Vikas Kumar
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Shelly Gulati
- Department of Biochemistry & Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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8
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Cinquin A, Chiang M, Paz A, Hallman S, Yuan O, Vysniauskaite I, Fowlkes CC, Cinquin O. Intermittent Stem Cell Cycling Balances Self-Renewal and Senescence of the C. elegans Germ Line. PLoS Genet 2016; 12:e1005985. [PMID: 27077385 PMCID: PMC4831802 DOI: 10.1371/journal.pgen.1005985] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 03/18/2016] [Indexed: 11/22/2022] Open
Abstract
Self-renewing organs often experience a decline in function in the course of aging. It is unclear whether chronological age or external factors control this decline, or whether it is driven by stem cell self-renewal—for example, because cycling cells exhaust their replicative capacity and become senescent. Here we assay the relationship between stem cell cycling and senescence in the Caenorhabditis elegans reproductive system, defining this senescence as the progressive decline in “reproductive capacity,” i.e. in the number of progeny that can be produced until cessation of reproduction. We show that stem cell cycling diminishes remaining reproductive capacity, at least in part through the DNA damage response. Paradoxically, gonads kept under conditions that preclude reproduction keep cycling and producing cells that undergo apoptosis or are laid as unfertilized gametes, thus squandering reproductive capacity. We show that continued activity is in fact beneficial inasmuch as gonads that are active when reproduction is initiated have more sustained early progeny production. Intriguingly, continued cycling is intermittent—gonads switch between active and dormant states—and in all likelihood stochastic. Other organs face tradeoffs whereby stem cell cycling has the beneficial effect of providing freshly-differentiated cells and the detrimental effect of increasing the likelihood of cancer or senescence; stochastic stem cell cycling may allow for a subset of cells to preserve proliferative potential in old age, which may implement a strategy to deal with uncertainty as to the total amount of proliferation to be undergone over an organism’s lifespan. Stem cell cycling is expected to be beneficial because it helps delay aging, by ensuring organ self-renewal. Yet stem cell cycling is best used sparingly: cycling likely causes mutation accumulation—increasing the likelihood of cancer—and may eventually cause stem cells to senesce and thus stop contributing to organ self renewal. It is unknown how self-renewing organs make tradeoffs between benefits and drawbacks of stem cell cycling. Here we use the C. elegans reproductive system as a model organ. We characterize benefits and drawbacks of stem cell cycling—which are keeping worms primed for reproduction, and reducing the number of future progeny worms may bear, respectively. We show that, under specific conditions of reproductive inactivity, stem cells switch back and forth between active and dormant states; the timing of these switches, whose genetic control we start delineating, appears random. This randomness may help explain why populations of aging, reproductively-inactive worms experience an increase in the variability of their reproductive capacity. Stochastic stem cell cycling may underlie tradeoffs between self-renewal and senescence in other organs.
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Affiliation(s)
- Amanda Cinquin
- Department of Developmental & Cell Biology, University of California, Irvine, Irvine, California, United States of America
- Center for Complex Biological Systems, University of California, Irvine, Irvine, California, United States of America
| | - Michael Chiang
- Department of Developmental & Cell Biology, University of California, Irvine, Irvine, California, United States of America
- Center for Complex Biological Systems, University of California, Irvine, Irvine, California, United States of America
| | - Adrian Paz
- Department of Developmental & Cell Biology, University of California, Irvine, Irvine, California, United States of America
- Center for Complex Biological Systems, University of California, Irvine, Irvine, California, United States of America
| | - Sam Hallman
- Center for Complex Biological Systems, University of California, Irvine, Irvine, California, United States of America
- Department of Computer Science, University of California, Irvine, Irvine, California, United States of America
| | - Oliver Yuan
- Department of Developmental & Cell Biology, University of California, Irvine, Irvine, California, United States of America
- Center for Complex Biological Systems, University of California, Irvine, Irvine, California, United States of America
| | - Indre Vysniauskaite
- Department of Developmental & Cell Biology, University of California, Irvine, Irvine, California, United States of America
- Center for Complex Biological Systems, University of California, Irvine, Irvine, California, United States of America
| | - Charless C. Fowlkes
- Center for Complex Biological Systems, University of California, Irvine, Irvine, California, United States of America
- Department of Computer Science, University of California, Irvine, Irvine, California, United States of America
| | - Olivier Cinquin
- Department of Developmental & Cell Biology, University of California, Irvine, Irvine, California, United States of America
- Center for Complex Biological Systems, University of California, Irvine, Irvine, California, United States of America
- * E-mail:
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9
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Aprison EZ, Ruvinsky I. Balanced trade-offs between alternative strategies shape the response of C. elegans reproduction to chronic heat stress. PLoS One 2014; 9:e105513. [PMID: 25165831 PMCID: PMC4148340 DOI: 10.1371/journal.pone.0105513] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 07/24/2014] [Indexed: 11/18/2022] Open
Abstract
To ensure long-term reproductive success organisms have to cope with harsh environmental extremes. A reproductive strategy that simply maximizes offspring production is likely to be disadvantageous because it could lead to a catastrophic loss of fecundity under unfavorable conditions. To understand how an appropriate balance is achieved, we investigated reproductive performance of C. elegans under conditions of chronic heat stress. We found that following even prolonged exposure to temperatures at which none of the offspring survive, worms could recover and resume reproduction. The likelihood of producing viable offspring falls precipitously after exposure to temperatures greater than 28°C primarily due to sperm damage. Surprisingly, we found that worms that experienced higher temperatures can recover considerably better, provided they did not initiate ovulation. Therefore mechanisms controlling this process must play a crucial role in determining the probability of recovery. We show, however, that suppressing ovulation is only beneficial under relatively long stresses, whereas it is a disadvantageous strategy under shorter stresses of the same intensity. This is because the benefit of shutting down egg laying, and thus protecting the reproductive system, is negated by the cost associated with implementing this strategy--it takes considerable time to recover and produce offspring. We interpret these balanced trade-offs as a dynamic response of the C. elegans reproductive system to stress and an adaptation to life in variable and unpredictable conditions.
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Affiliation(s)
- Erin Z. Aprison
- Department of Ecology and Evolution and Institute for Genomics and Systems Biology, The University of Chicago, Chicago, Illinois, United States of America
| | - Ilya Ruvinsky
- Department of Ecology and Evolution and Institute for Genomics and Systems Biology, The University of Chicago, Chicago, Illinois, United States of America
- Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, Illinois, United States of America
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10
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Bachtrog D, Mank JE, Peichel CL, Kirkpatrick M, Otto SP, Ashman TL, Hahn MW, Kitano J, Mayrose I, Ming R, Perrin N, Ross L, Valenzuela N, Vamosi JC. Sex determination: why so many ways of doing it? PLoS Biol 2014; 12:e1001899. [PMID: 24983465 PMCID: PMC4077654 DOI: 10.1371/journal.pbio.1001899] [Citation(s) in RCA: 702] [Impact Index Per Article: 70.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Sexual reproduction is an ancient feature of life on earth, and the familiar X and Y chromosomes in humans and other model species have led to the impression that sex determination mechanisms are old and conserved. In fact, males and females are determined by diverse mechanisms that evolve rapidly in many taxa. Yet this diversity in primary sex-determining signals is coupled with conserved molecular pathways that trigger male or female development. Conflicting selection on different parts of the genome and on the two sexes may drive many of these transitions, but few systems with rapid turnover of sex determination mechanisms have been rigorously studied. Here we survey our current understanding of how and why sex determination evolves in animals and plants and identify important gaps in our knowledge that present exciting research opportunities to characterize the evolutionary forces and molecular pathways underlying the evolution of sex determination.
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Affiliation(s)
- Doris Bachtrog
- University of California, Berkeley, Department of Integrative Biology, Berkeley, California, United States of America
| | - Judith E. Mank
- University College London, Department of Genetics, Evolution and Environment, London, United Kingdom
| | - Catherine L. Peichel
- Fred Hutchinson Cancer Research Center, Divisions of Human Biology and Basic Sciences, Seattle, Washington, United States of America
| | - Mark Kirkpatrick
- University of Texas, Department of Integrative Biology, Austin, Texas, United States of America
| | - Sarah P. Otto
- University of British Columbia, Department of Zoology, Vancouver, British Columbia, Canada
| | - Tia-Lynn Ashman
- University of Pittsburgh, Department of Biological Sciences, Pittsburgh, Pennsylvania, United States of America
| | - Matthew W. Hahn
- Indiana University, Department of Biology, Bloomington Indiana, United States of America
| | - Jun Kitano
- National Institute of Genetics, Ecological Genetics Laboratory, Mishima, Shizuoka, Japan
| | - Itay Mayrose
- Tel Aviv University, Department of Molecular Biology and Ecology of Plants, Tel Aviv, Israel
| | - Ray Ming
- University of Illinois, Department of Plant Biology, Urbana-Champaign, Illinois, United States of America
| | - Nicolas Perrin
- University of Lausanne, Department of Ecology and Evolution, Lausanne, Switzerland
| | - Laura Ross
- University of Oxford, Department of Zoology, Oxford, United Kingdom
| | - Nicole Valenzuela
- Iowa State University, Department of Ecology, Evolution and Organismal Biology, Ames, Iowa, United States of America
| | - Jana C. Vamosi
- University of Calgary, Department of Biological Sciences, Calgary, Alberta, Canada
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11
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Li T, Kelly WG. A role for WDR5 in TRA-1/Gli mediated transcriptional control of the sperm/oocyte switch in C. elegans. Nucleic Acids Res 2014; 42:5567-81. [PMID: 24682813 PMCID: PMC4027197 DOI: 10.1093/nar/gku221] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The hermaphrodite germline of Caenorhabditis elegans initially engages in spermatogenesis and then switches to oogenesis during late stages of larval development. TRA-1, a member of the Ci/Gli family of transcriptional repressors, plays an essential role in this switch by repressing genes that promote spermatogenesis. WDR5 proteins are conserved components of histone methyltransferase complexes normally associated with gene activation. However, two C. elegans WDR5 homologs, wdr-5.1 and wdr-5.2 are redundantly required for normal TRA-1 dependent repression, and this function is independent of their roles in histone methylation. Animals lacking wdr-5.1/wdr-5.2 function fail to switch to oogenesis at 25°C, resulting in a masculinization of germline (Mog) phenotype. The Mog phenotype is caused by ectopic expression of fog-3, a direct target of TRA-1 repression. WDR-5.1 associates with the fog-3 promoter and is required for TRA-1 to bind to fog-3 promoter. Other direct targets of TRA-1 are similarly derepressed in the double mutant. These results show that WDR5 plays a novel and important role in stabilizing transcriptional repression during C. elegans sex determination, and provide evidence that this important protein may operate independently of its established role in histone methyltransferase complexes.
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Affiliation(s)
- Tengguo Li
- Biology Department, Emory University, Atlanta, GA 30322, USA
| | - William G Kelly
- Biology Department, Emory University, Atlanta, GA 30322, USA
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12
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Gray JC, Cutter AD. Mainstreaming Caenorhabditis elegans in experimental evolution. Proc Biol Sci 2014; 281:20133055. [PMID: 24430852 DOI: 10.1098/rspb.2013.3055] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Experimental evolution provides a powerful manipulative tool for probing evolutionary process and mechanism. As this approach to hypothesis testing has taken purchase in biology, so too has the number of experimental systems that use it, each with its own unique strengths and weaknesses. The depth of biological knowledge about Caenorhabditis nematodes, combined with their laboratory tractability, positions them well for exploiting experimental evolution in animal systems to understand deep questions in evolution and ecology, as well as in molecular genetics and systems biology. To date, Caenorhabditis elegans and related species have proved themselves in experimental evolution studies of the process of mutation, host-pathogen coevolution, mating system evolution and life-history theory. Yet these organisms are not broadly recognized for their utility for evolution experiments and remain underexploited. Here, we outline this experimental evolution work undertaken so far in Caenorhabditis, detail simple methodological tricks that can be exploited and identify research areas that are ripe for future discovery.
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Affiliation(s)
- Jeremy C Gray
- Department of Ecology and Evolutionary Biology, University of Toronto, , 25 Willcocks Street, Toronto, Ontario, Canada , M5S 3B2
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13
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Guo Y, Chen X, Ellis RE. Evolutionary change within a bipotential switch shaped the sperm/oocyte decision in hermaphroditic nematodes. PLoS Genet 2013; 9:e1003850. [PMID: 24098152 PMCID: PMC3789826 DOI: 10.1371/journal.pgen.1003850] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 08/17/2013] [Indexed: 01/11/2023] Open
Abstract
A subset of transcription factors like Gli2 and Oct1 are bipotential--they can activate or repress the same target, in response to changing signals from upstream genes. Some previous studies implied that the sex-determination protein TRA-1 might also be bipotential; here we confirm this hypothesis by identifying a co-factor, and use it to explore how the structure of a bipotential switch changes during evolution. First, null mutants reveal that C. briggsae TRR-1 is required for spermatogenesis, RNA interference implies that it works as part of the Tip60 Histone Acetyl Transferase complex, and RT-PCR data show that it promotes the expression of Cbr-fog-3, a gene needed for spermatogenesis. Second, epistasis tests reveal that TRR-1 works through TRA-1, both to activate Cbr-fog-3 and to control the sperm/oocyte decision. Since previous studies showed that TRA-1 can repress fog-3 as well, these observations demonstrate that it is bipotential. Third, TRR-1 also regulates the development of the male tail. Since Cbr-tra-2 Cbr-trr-1 double mutants resemble Cbr-tra-1 null mutants, these two regulatory branches control all tra-1 activity. Fourth, striking differences in the relationship between these two branches of the switch have arisen during recent evolution. C. briggsae trr-1 null mutants prevent hermaphrodite spermatogenesis, but not Cbr-fem null mutants, which disrupt the other half of the switch. On the other hand, C. elegans fem null mutants prevent spermatogenesis, but not Cel-trr-1 mutants. However, synthetic interactions confirm that both halves of the switch exist in each species. Thus, the relationship between the two halves of a bipotential switch can shift rapidly during evolution, so that the same phenotype is produce by alternative, complementary mechanisms.
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Affiliation(s)
- Yiqing Guo
- Department of Molecular Biology, Rowan-SOM and the UMDNJ-SOM, B303 Science Center, Stratford, New Jersey, United States of America
| | - Xiangmei Chen
- Department of Molecular Biology, Rowan-SOM and the UMDNJ-SOM, B303 Science Center, Stratford, New Jersey, United States of America
| | - Ronald E. Ellis
- Department of Molecular Biology, Rowan-SOM and the UMDNJ-SOM, B303 Science Center, Stratford, New Jersey, United States of America
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Zanetti S, Puoti A. Sex Determination in the Caenorhabditis elegans Germline. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 757:41-69. [DOI: 10.1007/978-1-4614-4015-4_3] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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15
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Using Caenorhabditis to Explore the Evolution of the Germ Line. GERM CELL DEVELOPMENT IN C. ELEGANS 2013; 757:405-25. [DOI: 10.1007/978-1-4614-4015-4_14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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16
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Sengupta MS, Low WY, Patterson JR, Kim HM, Traven A, Beilharz TH, Colaiácovo MP, Schisa JA, Boag PR. ifet-1 is a broad-scale translational repressor required for normal P granule formation in C. elegans. J Cell Sci 2012; 126:850-9. [PMID: 23264733 DOI: 10.1242/jcs.119834] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Large cytoplasmic ribonucleoprotein germ granule complexes are a common feature in germ cells. In C. elegans these are called P granules and for much of the life-cycle they associate with nuclear pore complexes in germ cells. P granules are rich in proteins that function in diverse RNA pathways. Here we report that the C. elegans homolog of the eIF4E-transporter IFET-1 is required for oogenesis but not spermatogenesis. We show that IFET-1 is required for translational repression of several maternal mRNAs in the distal gonad and functions in conjunction with the broad-scale translational regulators CGH-1, CAR-1 and PATR-1 to regulate germ cell sex determination. Furthermore we have found that IFET-1 localizes to P granules throughout the gonad and in the germ cell lineage in the embryo. Interestingly, IFET-1 is required for the normal ultrastructure of P granules and for the localization of CGH-1 and CAR-1 to P granules. Our findings suggest that IFET-1 is a key translational regulator and is required for normal P granule formation.
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Affiliation(s)
- Madhu S Sengupta
- Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
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17
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Abstract
The germ line represents a continuous cellular link between generations and between species, but the germ cells themselves develop in a specialized, organism-specific context. The model organisms Caenorhabditis elegans, Drosophila melanogaster and the mouse display striking similarities, as well as major differences, in the means by which they control germ cell development. Recent developments in genetic technologies allow a more detailed comparison of the germ cells of these three organisms than has previously been possible, shedding light not only on universal aspects of germline regulation, but also on the control of the pluripotent state in vivo and on the earliest steps of embryogenesis. Here, we highlight themes from the comparison of these three alternative strategies for navigating the fundamental cycle of sexual reproduction.
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18
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Chandler CH, Chadderdon GE, Phillips PC, Dworkin I, Janzen FJ. Experimental evolution of the Caenorhabditis elegans sex determination pathway. Evolution 2011; 66:82-93. [PMID: 22220866 DOI: 10.1111/j.1558-5646.2011.01420.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Sex determination is a critical developmental decision with major ecological and evolutionary consequences, yet a large variety of sex determination mechanisms exist and we have a poor understanding of how they evolve. Theoretical and empirical work suggest that compensatory adaptations to mutations in genes involved in sex determination may play a role in the evolution of these pathways. Here, we directly address this problem using experimental evolution in Caenorhabditis elegans lines fixed for a pair of mutations in two key sex-determining genes that jointly render sex determination temperature-sensitive and cause intersexual (but still weakly to moderately fertile) phenotypes at intermediate temperatures. After 50 generations, evolved lines clearly recovered toward wild-type phenotypes. However, changes in transcript levels of key sex-determining genes in evolved lines cannot explain their partially (or in some cases, nearly completely) rescued phenotypes, implying that wild-type phenotypes can be restored independently of the transcriptional effects of these mutations. Our findings highlight the microevolutionary flexibility of sex determination pathways and suggest that compensatory adaptation to mutations can elicit novel and unpredictable evolutionary trajectories in these pathways, mirroring the phylogenetic diversity, and macroevolutionary dynamics of sex determination mechanisms.
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Affiliation(s)
- Christopher H Chandler
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa 50011, USA
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19
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Baldi C, Viviano J, Ellis RE. A bias caused by ectopic development produces sexually dimorphic sperm in nematodes. Curr Biol 2011; 21:1416-20. [PMID: 21835620 DOI: 10.1016/j.cub.2011.07.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2011] [Revised: 06/07/2011] [Accepted: 07/21/2011] [Indexed: 10/17/2022]
Abstract
Self-fertile hermaphrodites have evolved independently several times in the genus Caenorhabditis [1, 2]. These XX hermaphrodites make smaller sperm than males [3, 4], which they use to fertilize their own oocytes. Because larger sperm outcompete smaller sperm in nematodes [3-5], it had been assumed that this dimorphism evolved in response to sperm competition. However, we show that it was instead caused by a developmental bias. When we transformed females of the species Caenorhabditis remanei into hermaphrodites [6], their sperm were significantly smaller than those of males. Because this species never makes hermaphrodites in the wild, this dimorphism cannot be due to selection. Instead, analyses of the related nematode Caenorhabditis elegans suggest that this dimorphism might reflect the development of sperm within the distinct physiological environment of the hermaphrodite gonad. These results reveal a new mechanism for some types of developmental bias-the effects of a novel physical location alter the development of ectopic cells in predictable ways.
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Affiliation(s)
- Christopher Baldi
- Graduate School of Biomedical Sciences, The UMDNJ School of Osteopathic Medicine, B303 Science Center, 2 Medical Center Drive, Stratford, NJ 08084, USA
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20
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Murray SM, Yang SY, Van Doren M. Germ cell sex determination: a collaboration between soma and germline. Curr Opin Cell Biol 2010; 22:722-9. [PMID: 21030233 DOI: 10.1016/j.ceb.2010.09.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 09/27/2010] [Accepted: 09/27/2010] [Indexed: 01/28/2023]
Abstract
Sex determination is regulated very differently in the soma vs. the germline, yet both processes are critical for the creation of the male and female gametes. In general, the soma plays an essential role in regulating sexual identity of the germline. However, in some species, such as Drosophila and mouse, the sex chromosome constitution of the germ cells makes an autonomous contribution to germline sexual development. Here we review how the soma and germline cooperate to determine germline sexual identity for some important model systems, the fly, the worm and the mouse, and discuss some of the implications of 'dual control' (soma plus germline) as compared to species where germline sex is dictated only by the surrounding soma.
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Affiliation(s)
- Sheryl M Murray
- Department of Biology, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
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21
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Han SM, Cottee PA, Miller MA. Sperm and oocyte communication mechanisms controlling C. elegans fertility. Dev Dyn 2010; 239:1265-81. [PMID: 20034089 DOI: 10.1002/dvdy.22202] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
During sexual reproduction in many species, sperm and oocyte secrete diffusible signaling molecules to help orchestrate the biological symphony of fertilization. In the Caenorhabditis elegans gonad, bidirectional signaling between sperm and oocyte is important for guiding sperm to the fertilization site and inducing oocyte maturation. The molecular mechanisms that regulate sperm guidance and oocyte maturation are being delineated. Unexpectedly, these mechanisms are providing insight into human diseases, such as amyotrophic lateral sclerosis, spinal muscular atrophy, and cancer. Here we review sperm and oocyte communication in C. elegans and discuss relationships to human disorders.
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Affiliation(s)
- Sung Min Han
- Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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22
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Zanin E, Pacquelet A, Scheckel C, Ciosk R, Gotta M. LARP-1 promotes oogenesis by repressing fem-3 in the C. elegans germline. J Cell Sci 2010; 123:2717-24. [PMID: 20663921 DOI: 10.1242/jcs.066761] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
LA-related protein 1 (LARP-1) belongs to an RNA-binding protein family containing a LA motif. Here, we identify LARP-1 as a regulator of sex determination. In C. elegans hermaphrodites, a complex regulatory network regulates the switch from sperm to oocyte production. We find that simultaneous depletion of larp-1 and the Nanos homologue nos-3 results in germline masculinization. This phenotype is accompanied by a strong reduction of the levels of TRA-1, a GLI-family transcription factor that promotes oogenesis. TRA-1 levels are regulated by CBC(FEM-1), a ubiquitin ligase consisting of the FEM proteins, FEM-1, FEM-2 and FEM-3 and the cullin CUL-2. We show that both the masculinization phenotype and the reduction of TRA-1 levels observed in nos-3;larp-1 mutants require fem-3 activity, suggesting that nos-3 and larp-1 regulate the sperm-oocyte switch by inhibiting the fem genes. Consistently, fem-3 mRNA levels are increased in larp-1 mutants. By contrast, levels of fem-3 mRNA are not affected in nos-3 mutants. Therefore, our data indicate that LARP-1 and NOS-3 promote oogenesis by regulating fem-3 expression through distinct mechanisms.
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Affiliation(s)
- Esther Zanin
- ETH Zurich, Institute of Biochemistry, Zurich, Switzerland
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23
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Tops BBJ, Gauci S, Heck AJR, Krijgsveld J. Worms from venus and mars: proteomics profiling of sexual differences in Caenorhabditis elegans using in vivo 15N isotope labeling. J Proteome Res 2010; 9:341-51. [PMID: 19916504 DOI: 10.1021/pr900678j] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Hermaphrodites of the nematode Caenorhabditis elegans produce both sperm and oocytes in the same germline. To investigate the process underlying spermatogenesis and oogenesis separately, we used a quantitative proteomics approach applied to two mutant worm lines (fem-3(q20) and fem-1(hc17)) developing only male and female germlines, respectively. We used stable isotopic labeling of whole animals by feeding them either (14)N or (15)N labeled Escherichia coli. This way, we could confidently identify and quantify 1040 proteins in two independent experiments. Of these, approximately 400 proteins showed significant differential expression between female-like and male-like animals. As expected, proteins linked to oogenesis were found to be highly upregulated in the feminized worms, whereas proteins involved in spermatogenesis were found to be highly upregulated in the masculinized worms. This was complemented by many proteins strongly enriched in either mutant. Although the function of the majority of these proteins is unknown, their expression profile indicates that they have an as yet unrecognized role in the development and/or function of the female- and male germline in C. elegans. We show that members of several protein complexes as well as functionally similar proteins show comparable abundance ratios, indicating coregulation of protein expression. Additional analysis comparing our protein data to a previously published microarray data set shows that mRNA and protein expression are poorly correlating. We provide one of the first examples of a large-scale quantitative proteomics experiment in C. elegans and show the potential and feasibility of an approach enabling system-wide accurate quantitative proteomics experiments in this model organism.
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Affiliation(s)
- Bastiaan B J Tops
- Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Centre for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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24
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Racher H, Hansen D. Translational control in the C. elegans hermaphrodite germ line. Genome 2010; 53:83-102. [DOI: 10.1139/g09-090] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The formation of a fully developed gamete from an undifferentiated germ cell requires progression through numerous developmental stages and cell fate decisions. The precise timing and level of gene expression guides cells through these stages. Translational regulation is highly utilized in the germ line of many species, including Caenorhabditis elegans , to regulate gene expression and ensure the proper formation of gametes. In this review, we discuss some of the developmental stages and cell fate decisions involved in the formation of functional gametes in the C. elegans germ line in which translational control has been implicated. These stages include the mitosis versus meiosis decision, the sperm/oocyte decision, and gamete maturation. We also discuss some of the techniques used to identify mRNA targets; the identification of these targets is necessary to clearly understand the role each RNA-binding protein plays in these decisions. Relatively few mRNA targets have been identified, thus providing a major focus for future research. Finally, we propose some reasons why translational control may be utilized so heavily in the germ line. Given that many species have this substantial reliance on translational regulation for the control of gene expression in the germ line, an understanding of translational regulation in the C. elegans germ line is likely to increase our understanding of gamete formation in general.
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Affiliation(s)
- Hilary Racher
- University of Calgary, 2500 University Drive, Department of Biological Sciences, Calgary, AB T2N 1N4, Canada
| | - Dave Hansen
- University of Calgary, 2500 University Drive, Department of Biological Sciences, Calgary, AB T2N 1N4, Canada
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25
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Baldi C, Cho S, Ellis RE. Mutations in Two Independent Pathways Are Sufficient to Create Hermaphroditic Nematodes. Science 2009; 326:1002-5. [DOI: 10.1126/science.1176013] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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26
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Casper AL, Van Doren M. The establishment of sexual identity in the Drosophila germline. Development 2009; 136:3821-30. [PMID: 19855024 PMCID: PMC2766343 DOI: 10.1242/dev.042374] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/14/2009] [Indexed: 12/11/2022]
Abstract
The establishment of sexual identity is a crucial step of germ cell development in sexually reproducing organisms. Sex determination in the germline is controlled differently than in the soma, and often depends on communication from the soma. To investigate how sexual identity is established in the Drosophila germline, we first conducted a molecular screen for genes expressed in a sex-specific manner in embryonic germ cells. Sex-specific expression of these genes is initiated at the time of gonad formation (stage 15), indicating that sexual identity in the germline is established by this time. Experiments where the sex of the soma was altered relative to that of the germline (by manipulating transformer) reveal a dominant role for the soma in regulating initial germline sexual identity. Germ cells largely take on the sex of the surrounding soma, although the sex chromosome constitution of the germ cells still plays some role at this time. The male soma signals to the germline through the JAK/STAT pathway, while the nature of the signal from the female soma remains unknown. We also find that the genes ovo and ovarian tumor (otu) are expressed in a female-specific manner in embryonic germ cells, consistent with their role in promoting female germline identity. However, removing the function of ovo and otu, or reducing germline function of Sex lethal, had little effect on establishment of germline sexual identity. This is consistent with our findings that signals from the soma are dominant over germline autonomous cues at the initial stage of germline sex determination.
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Affiliation(s)
- Abbie L Casper
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
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27
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Guo Y, Lang S, Ellis RE. Independent recruitment of F box genes to regulate hermaphrodite development during nematode evolution. Curr Biol 2009; 19:1853-60. [PMID: 19836240 DOI: 10.1016/j.cub.2009.09.042] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Revised: 08/25/2009] [Accepted: 09/01/2009] [Indexed: 10/20/2022]
Abstract
Elucidating the molecular mechanisms that created ancient complex traits like insect wings is difficult. Fortunately, some complex traits have arisen recently. For example, hermaphroditic reproduction evolved independently many times during recent nematode evolution. Although C. elegans hermaphrodites require fog-2, which encodes an F box protein that regulates the translation of tra-2 mRNAs, the related species C. briggsae lacks fog-2. We identified a critical regulator of hermaphrodite development in C. briggsae, named she-1. Analysis of double mutants indicates that she-1 acts upstream of tra-2 in C. briggsae, just as fog-2 does in C. elegans. Molecular cloning shows that she-1 encodes a novel F box protein that was created by a recent gene duplication. Whereas FOG-2 acts through GLD-1 in C. elegans, SHE-1 does not bind GLD-1 in C. briggsae. Thus, both species recruited F box genes produced by recent duplication events into the sex-determination pathway to control hermaphrodite development, but these genes have distinct activities. This result implies that some gene families are more likely to give rise to novel regulatory genes than other families. Finally, we note that null mutations of she-1 are temperature sensitive, so C. briggsae might once have been a facultative hermaphrodite.
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Affiliation(s)
- Yiqing Guo
- Department of Molecular Biology, School of Osteopathic Medicine, The University of Medicine and Dentistry of New Jersey, B303 Science Center, 2 Medical Center Drive, Stratford, NJ 08084, USA
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