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Oh Y, Kasu M, Bottoms CJ, Douglas JC, Sekulovski N, Hayashi K, MacLean II JA. Rhox8 homeobox gene ablation leads to rete testis abnormality and male subfertility in mice†. Biol Reprod 2023; 109:520-532. [PMID: 37471646 PMCID: PMC10577278 DOI: 10.1093/biolre/ioad077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 07/10/2023] [Accepted: 07/15/2023] [Indexed: 07/22/2023] Open
Abstract
The reproductive homeobox X-linked (Rhox) genes encode transcription factors that are expressed selectively in reproductive tissues including the testis, epididymis, ovary, and placenta. While many Rhox genes are expressed in germ cells in the mouse testis, only Rhox8 is expressed exclusively in the Sertoli cells during embryonic and postnatal development, suggesting a possible role of Rhox8 in embryonic gonad development. Previously, Sertoli cell-specific knockdown of RHOX8 resulted in male subfertility due to germ cell defects. However, this knockdown model was limited in examining the functions of Rhox8 as RHOX8 knockdown occurred only postnatally, and there was still residual RHOX8 in the testis. In this study, we generated new Rhox8 knockout (KO) mice using the CRISPR/Cas9 system. Sex determination and fetal testis development were apparently normal in mutant mice. Fertility analysis showed a low fecundity in Rhox8 KO adult males, with disrupted spermatogenic cycles, increased germ cell apoptosis, and reduced sperm count and motility. Interestingly, Rhox8 KO testes showed an increase in testis size with dilated seminiferous tubules and rete testis, which might be affected by efferent duct (ED) Rhox8 ablation dysregulating the expression of metabolism and transport genes in the EDs. Taken together, the data presented in this study suggest that Rhox8 in the Sertoli cells is not essential for sex determination and embryonic testis differentiation but has an important role in complete spermatogenesis and optimal male fertility.
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Affiliation(s)
- Yeongseok Oh
- Center for Reproductive Biology, School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
- Department of Physiology, Southern Illinois School of Medicine, Carbondale, IL, USA
| | - Maho Kasu
- Center for Reproductive Biology, School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
| | - Constence J Bottoms
- Center for Reproductive Biology, School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
| | - Jenna C Douglas
- Center for Reproductive Biology, School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
| | - Nikola Sekulovski
- Department of Physiology, Southern Illinois School of Medicine, Carbondale, IL, USA
| | - Kanako Hayashi
- Center for Reproductive Biology, School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
- Department of Physiology, Southern Illinois School of Medicine, Carbondale, IL, USA
| | - James A MacLean II
- Center for Reproductive Biology, School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
- Department of Physiology, Southern Illinois School of Medicine, Carbondale, IL, USA
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Le Beulze M, Daubech C, Balde-Camara A, Ghieh F, Vialard F. Mammal Reproductive Homeobox (Rhox) Genes: An Update of Their Involvement in Reproduction and Development. Genes (Basel) 2023; 14:1685. [PMID: 37761825 PMCID: PMC10531175 DOI: 10.3390/genes14091685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 08/16/2023] [Accepted: 08/23/2023] [Indexed: 09/29/2023] Open
Abstract
The reproductive homeobox on the X chromosome (RHOX) genes were first identified in the mouse during the 1990s and have a crucial role in reproduction. In various transcription factors with a key regulatory role, the homeobox sequence encodes a "homeodomain" DNA-binding motif. In the mouse, there are three clusters of Rhox genes (α, β, and γ) on the X chromosome. Each cluster shows temporal and/or quantitative collinearity, which regulates the progression of the embryonic development process. Although the RHOX family is conserved in mammals, the interspecies differences in the number of RHOX genes and pseudogenes testifies to a rich evolutionary history with several relatively recent events. In the mouse, Rhox genes are mainly expressed in reproductive tissues, and several have a role in the differentiation of primordial germ cells (Rhox1, Rhox6, and Rhox10) and in spermatogenesis (Rhox1, Rhox8, and Rhox13). Despite the lack of detailed data on human RHOX, these genes appear to be involved in the formation of germ cells because they are predominantly expressed during the early (RHOXF1) and late (RHOXF2/F2B) stages of germ cell development. Furthermore, the few variants identified to date are thought to induce or predispose to impaired spermatogenesis and severe oligozoospermia or azoospermia. In the future, research on the pathophysiology of the human RHOX genes is likely to confirm the essential role of this family in the reproductive process and might help us to better understand the various causes of infertility and characterize the associated human phenotypes.
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Affiliation(s)
- Morgane Le Beulze
- Equipe RHuMA, UMR-BREED, UFR Simone Veil Santé, F-78180 Montigny-le-Bretonneux, France; (M.L.B.); (C.D.); (A.B.-C.); (F.G.)
- UFR des Sciences de la Santé Simone Veil, Université de Versailles-Saint Quentin en Yvelines—Université Paris Saclay (UVSQ), INRAE, BREED, F-78350 Jouy-en-Josas, France
| | - Cécile Daubech
- Equipe RHuMA, UMR-BREED, UFR Simone Veil Santé, F-78180 Montigny-le-Bretonneux, France; (M.L.B.); (C.D.); (A.B.-C.); (F.G.)
- UFR des Sciences de la Santé Simone Veil, Université de Versailles-Saint Quentin en Yvelines—Université Paris Saclay (UVSQ), INRAE, BREED, F-78350 Jouy-en-Josas, France
| | - Aissatu Balde-Camara
- Equipe RHuMA, UMR-BREED, UFR Simone Veil Santé, F-78180 Montigny-le-Bretonneux, France; (M.L.B.); (C.D.); (A.B.-C.); (F.G.)
- UFR des Sciences de la Santé Simone Veil, Université de Versailles-Saint Quentin en Yvelines—Université Paris Saclay (UVSQ), INRAE, BREED, F-78350 Jouy-en-Josas, France
| | - Farah Ghieh
- Equipe RHuMA, UMR-BREED, UFR Simone Veil Santé, F-78180 Montigny-le-Bretonneux, France; (M.L.B.); (C.D.); (A.B.-C.); (F.G.)
- UFR des Sciences de la Santé Simone Veil, Université de Versailles-Saint Quentin en Yvelines—Université Paris Saclay (UVSQ), INRAE, BREED, F-78350 Jouy-en-Josas, France
| | - François Vialard
- Equipe RHuMA, UMR-BREED, UFR Simone Veil Santé, F-78180 Montigny-le-Bretonneux, France; (M.L.B.); (C.D.); (A.B.-C.); (F.G.)
- UFR des Sciences de la Santé Simone Veil, Université de Versailles-Saint Quentin en Yvelines—Université Paris Saclay (UVSQ), INRAE, BREED, F-78350 Jouy-en-Josas, France
- Département de Génétique, CHI de Poissy St. Germain en Laye, F-78300 Poissy, France
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Li X, Chen P, Ji J, Duan Q, Cao J, Huang R, Ye SD. Rhox6 regulates the expression of distinct target genes to mediate mouse PGCLC formation and ESC self-renewal. Cell Biosci 2023; 13:145. [PMID: 37553721 PMCID: PMC10408072 DOI: 10.1186/s13578-023-01096-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 07/30/2023] [Indexed: 08/10/2023] Open
Abstract
BACKGROUND Mouse embryonic stem cells (mESCs) not only retain the property of self-renewal but also have the ability to develop into primordial germ cell-like cells (PGCLCs). However, knowledge about the mechanisms of transcriptional regulation is still limited. Rhox6, a member of the homeobox family that is located on the X chromosome, is highly expressed within PGCLCs in vivo and in vitro. However, the detailed effects of Rhox6 on PGCLC specification and mESC maintenance remain unclear. RESULTS In this study, we found that overexpression of Rhox6 favors the formation of PGCLCs, while depletion of Rhox6 inhibits the generation of PGCLCs. Mechanistically, Rhox6 directly induces the expression of Nanos3 during the specification of PGCLCs. Subsequently, downregulation of Nanos3 expression is sufficient to decrease the ability of Rhox6 to induce PGCLC formation. Moreover, we found that depletion of Rhox6 expression facilitates the self-renewal of mESCs. High-throughput sequencing revealed that suppression of Rhox6 transcription significantly increases the expression of pluripotency genes. Functional studies further demonstrated that Rhox6 directly represses the transcription of Tbx3. Therefore, knockdown of the expression of the latter impairs the self-renewal of mESCs promoted by Rhox6 downregulation. CONCLUSIONS Our study reveals that overexpression of Rhox6 is beneficial for PGCLC generation through induction of Nanos3, while downregulation of Rhox6 contributes to mESC self-renewal by increasing Tbx3. These findings help elucidate the early development of mouse embryos.
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Affiliation(s)
- Xiaofeng Li
- Center for Stem Cell and Translational Medicine, School of Life Sciences, Anhui University, Hefei, 230601, Anhui, China
| | - Peng Chen
- Center for Stem Cell and Translational Medicine, School of Life Sciences, Anhui University, Hefei, 230601, Anhui, China
| | - Junxiang Ji
- Center for Stem Cell and Translational Medicine, School of Life Sciences, Anhui University, Hefei, 230601, Anhui, China
| | - Quanchao Duan
- Center for Stem Cell and Translational Medicine, School of Life Sciences, Anhui University, Hefei, 230601, Anhui, China
| | - Jianjian Cao
- Center for Stem Cell and Translational Medicine, School of Life Sciences, Anhui University, Hefei, 230601, Anhui, China
| | - Ru Huang
- Center for Stem Cell and Translational Medicine, School of Life Sciences, Anhui University, Hefei, 230601, Anhui, China
| | - Shou-Dong Ye
- Center for Stem Cell and Translational Medicine, School of Life Sciences, Anhui University, Hefei, 230601, Anhui, China.
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Alhasnani MA, Loeb S, Hall SJ, Caruolo Z, Simmonds F, Solano AE, Spade DJ. Interaction between mono-(2-ethylhexyl) phthalate and retinoic acid alters Sertoli cell development during fetal mouse testis cord morphogenesis. Curr Res Toxicol 2022; 3:100087. [PMID: 36189433 PMCID: PMC9520016 DOI: 10.1016/j.crtox.2022.100087] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 09/17/2022] [Accepted: 09/17/2022] [Indexed: 11/24/2022] Open
Abstract
Phthalic acid esters (phthalates) are a class of industrial chemicals that cause developmental and reproductive toxicity, but there are significant gaps in knowledge of phthalate toxicity mechanisms. There is evidence that phthalates disrupt retinoic acid signaling in the fetal testis, potentially disrupting control of spatial and temporal patterns of testis development. Our goal was to determine how a phthalate would interact with retinoic acid signaling during fetal mouse testis development. We hypothesized that mono-(2-ethylhexyl) phthalate (MEHP) would exacerbate the adverse effect of all-trans retinoic acid (ATRA) on seminiferous cord development in the mouse fetal testis. To test this hypothesis, gestational day (GD) 14 C57BL/6 mouse testes were isolated and cultured on media containing MEHP, ATRA, or a combination of both compounds. Cultured testes were collected for global transcriptome analysis after one day in culture and for histology and immunofluorescent analysis of Sertoli cell differentiation after three days in culture. ATRA disrupted seminiferous cord morphogenesis and induced aberrant FOXL2 expression. MEHP alone had no significant effect on cord development, but combined exposure to MEHP and ATRA increased the number of FOXL2-positive cells, reduced seminiferous cord number, and increased testosterone levels, beyond the effect of ATRA alone. In RNA-seq analysis, ATRA treatment and MEHP treatment resulted in differential expression of genes 510 and 134 genes, respectively, including 70 common differentially expressed genes (DEGs) between the two treatments, including genes with known roles in fetal testis development. MEHP DEGs included RAR target genes, genes involved in angiogenesis, and developmental patterning genes, including members of the homeobox superfamily. These results support the hypothesis that MEHP modulates retinoic acid signaling in the mouse fetal testis and provide insight into potential mechanisms by which phthalates disrupt seminiferous cord morphogenesis.
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Key Words
- ATRA, All-trans retinoic acid. CAS # 302-79-4
- DMSO, dimethyl sulfoxide
- Fetal testis development
- GD, gestational day
- GO, Gene Ontology
- IPA, Ingenuity Pathway Analysis
- ITCN, Image-based Tool for Counting Nuclei
- MEHP, mono-(2-ethylheyxl) phthalate. CAS # 4376-20-9
- MNGs, multinucleated germ cells
- PVC, polyvinyl chloride
- Phthalate toxicity
- Retinoic acid
- Sertoli cell
- TDS, testicular dysgenesis syndrome
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Affiliation(s)
- Maha A. Alhasnani
- Department of Pathology and Laboratory Medicine, Brown University, Box G-E5, Providence, RI 02912, USA
| | - Skylar Loeb
- Department of Pathology and Laboratory Medicine, Brown University, Box G-E5, Providence, RI 02912, USA
| | - Susan J. Hall
- Department of Pathology and Laboratory Medicine, Brown University, Box G-E5, Providence, RI 02912, USA
| | - Zachary Caruolo
- Department of Pathology and Laboratory Medicine, Brown University, Box G-E5, Providence, RI 02912, USA
| | - Faith Simmonds
- Department of Pathology and Laboratory Medicine, Brown University, Box G-E5, Providence, RI 02912, USA
| | - Amanda E. Solano
- Department of Pathology and Laboratory Medicine, Brown University, Box G-E5, Providence, RI 02912, USA
| | - Daniel J. Spade
- Department of Pathology and Laboratory Medicine, Brown University, Box G-E5, Providence, RI 02912, USA
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5
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Abstract
Transposable elements (TEs) are mobile sequences that engender widespread mutations and thus are a major hazard that must be silenced. The most abundant active class of TEs in mammalian genomes is long interspersed element class 1 (LINE1). Here, we report that LINE1 transposition is suppressed in the male germline by transcription factors encoded by a rapidly evolving X-linked homeobox gene cluster. LINE1 transposition is repressed by many members of this RHOX transcription factor family, including those with different patterns of expression during spermatogenesis. One family member-RHOX10-suppresses LINE1 transposition during fetal development in vivo when the germline would otherwise be susceptible to LINE1 activation because of epigenetic reprogramming. We provide evidence that RHOX10 suppresses LINE transposition by inducing Piwil2, which encodes a key component in the Piwi-interacting RNA pathway that protects against TEs. The ability of RHOX transcription factors to suppress LINE1 is conserved in humans but is lost in RHOXF2 mutants from several infertile human patients, raising the possibility that loss of RHOXF2 causes human infertility by allowing uncontrolled LINE1 expression in the germline. Together, our results support a model in which the Rhox gene cluster is in an evolutionary arms race with TEs, resulting in expansion of the Rhox gene cluster to suppress TEs in different biological contexts.
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6
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Welborn JP, Davis MG, Ebers SD, Stodden GR, Hayashi K, Cheatwood JL, Rao MK, MacLean JA. Rhox8 Ablation in the Sertoli Cells Using a Tissue-Specific RNAi Approach Results in Impaired Male Fertility in Mice. Biol Reprod 2015; 93:8. [PMID: 25972016 DOI: 10.1095/biolreprod.114.124834] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Accepted: 05/11/2015] [Indexed: 12/27/2022] Open
Abstract
The reproductive homeobox X-linked, Rhox, genes encode transcription factors that are selectively expressed in reproductive tissues. While there are 33 Rhox genes in mice, only Rhox and Rhox8 are expressed in Sertoli cells, suggesting that they may regulate the expression of somatic-cell gene products crucial for germ cell development. We previously characterized Rhox5-null mice, which are subfertile, exhibiting excessive germ cell apoptosis and compromised sperm motility. To assess the role of Rhox8 in Sertoli cells, we used a tissue-specific RNAi approach to knockdown RHOX8 in vivo, in which the Rhox5 promoter was used to drive Rhox8-siRNA transgene expression in the postnatal Sertoli cells. Western and immunohistochemical analysis confirmed Sertoli-specific knockdown of RHOX8. However, other Sertoli markers, Gata1 and Rhox5, maintained normal expression patterns, suggesting that the knockdown was specific. Interestingly, male RHOX8-knockdown animals showed significantly reduced spermatogenic output, increased germ cell apoptosis, and compromised sperm motility, leading to impaired fertility. Importantly, our results revealed that while some RHOX5-dependent factors were also misregulated in Sertoli cells of RHOX8-knockdown animals, the majority were not, and novel putative RHOX8-regulated genes were identified. This suggests that while reduction in levels of RHOX5 and RHOX8 in Sertoli cells elicits similar phenotypes, these genes are not entirely redundant. Taken together, our study underscores the importance of Rhox genes in male fertility and suggests that Sertoli cell-specific expression of Rhox5 and Rhox8 is critical for complete male fertility.
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Affiliation(s)
- Joshua P Welborn
- Department of Physiology, Southern Illinois University School of Medicine, Carbondale, Illinois
| | - Matthew G Davis
- Department of Physiology, Southern Illinois University School of Medicine, Carbondale, Illinois
| | - Steven D Ebers
- Department of Physiology, Southern Illinois University School of Medicine, Carbondale, Illinois
| | - Genna R Stodden
- Department of Physiology, Southern Illinois University School of Medicine, Carbondale, Illinois
| | - Kanako Hayashi
- Department of Physiology, Southern Illinois University School of Medicine, Carbondale, Illinois
| | - Joseph L Cheatwood
- Department of Anatomy, Southern Illinois University School of Medicine, Carbondale, Illinois
| | - Manjeet K Rao
- Department of Cellular and Structural Biology, Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - James A MacLean
- Department of Physiology, Southern Illinois University School of Medicine, Carbondale, Illinois
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Rao MK, Matsumoto Y, Richardson ME, Panneerdoss S, Bhardwaj A, Ward JM, Shanker S, Bettegowda A, Wilkinson MF. Hormone-induced and DNA demethylation-induced relief of a tissue-specific and developmentally regulated block in transcriptional elongation. J Biol Chem 2014; 289:35087-101. [PMID: 25331959 DOI: 10.1074/jbc.m114.615435] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Genome-wide studies have revealed that genes commonly have a high density of RNA polymerase II just downstream of the transcription start site. This has raised the possibility that genes are commonly regulated by transcriptional elongation, but this remains largely untested in vivo, particularly in vertebrates. Here, we show that the proximal promoter from the Rhox5 homeobox gene recruits polymerase II and begins elongating in all tissues and cell lines that we tested, but it only completes elongation in a tissue-specific and developmentally regulated manner. Relief of the elongation block is associated with recruitment of the elongation factor P-TEFb, the co-activator GRIP1, the chromatin remodeling factor BRG1, and specific histone modifications. We provide evidence that two mechanisms relieve the elongation block at the proximal promoter: demethylation and recruitment of androgen receptor. Together, our findings support a model in which promoter proximal pausing helps confer tissue-specific and developmental gene expression through a mechanism regulated by DNA demethylation-dependent nuclear hormone receptor recruitment.
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Affiliation(s)
- Manjeet K Rao
- From the Department of Biochemistry and Molecular Biology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, the Greehey Children's Cancer Research Institute, Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio, Texas 78229
| | - Yuiko Matsumoto
- From the Department of Biochemistry and Molecular Biology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Marcy E Richardson
- the Department of Reproductive Medicine, University of California at San Diego, La Jolla, California 92037, the Institute of Genomic Medicine, University of California at San Diego, La Jolla, California 92093, and
| | - Subbarayalu Panneerdoss
- the Greehey Children's Cancer Research Institute, Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio, Texas 78229
| | - Anjana Bhardwaj
- From the Department of Biochemistry and Molecular Biology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Jacqueline M Ward
- the Department of Reproductive Medicine, University of California at San Diego, La Jolla, California 92037, the Institute of Genomic Medicine, University of California at San Diego, La Jolla, California 92093, and
| | - Sreenath Shanker
- From the Department of Biochemistry and Molecular Biology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Anilkumar Bettegowda
- From the Department of Biochemistry and Molecular Biology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, the Department of Reproductive Medicine, University of California at San Diego, La Jolla, California 92037, the Institute of Genomic Medicine, University of California at San Diego, La Jolla, California 92093, and
| | - Miles F Wilkinson
- From the Department of Biochemistry and Molecular Biology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, the Department of Reproductive Medicine, University of California at San Diego, La Jolla, California 92037, the Institute of Genomic Medicine, University of California at San Diego, La Jolla, California 92093, and
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8
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Richardson ME, Bleiziffer A, Tüttelmann F, Gromoll J, Wilkinson MF. Epigenetic regulation of the RHOX homeobox gene cluster and its association with human male infertility. Hum Mol Genet 2014; 23:12-23. [PMID: 23943794 PMCID: PMC3857941 DOI: 10.1093/hmg/ddt392] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 08/06/2013] [Indexed: 12/19/2022] Open
Abstract
The X-linked RHOX cluster encodes a set of homeobox genes that are selectively expressed in the reproductive tract. Members of the RHOX cluster regulate target genes important for spermatogenesis promote male fertility in mice. Studies show that demethylating agents strongly upregulate the expression of mouse Rhox genes, suggesting that they are regulated by DNA methylation. However, whether this extends to human RHOX genes, whether DNA methylation directly regulates RHOX gene transcription and how this relates to human male infertility are unknown. To address these issues, we first defined the promoter regions of human RHOX genes and performed gain- and loss-of-function experiments to determine whether human RHOX gene transcription is regulated by DNA methylation. Our results indicated that DNA methylation is necessary and sufficient to silence human RHOX gene expression. To determine whether RHOX cluster methylation associates with male infertility, we evaluated the methylation status of RHOX genes in sperm from a large cohort of infertility patients. Linear regression analysis revealed a strong association between RHOX gene cluster hypermethylation and three independent types of semen abnormalities. Hypermethylation was restricted specifically to the RHOX cluster; we did not observe it in genes immediately adjacent to it on the X chromosome. Our results strongly suggest that human RHOX homeobox genes are under an epigenetic control mechanism that is aberrantly regulated in infertility patients. We propose that hypermethylation of the RHOX gene cluster serves as a marker for idiopathic infertility and that it is a candidate to exert a causal role in male infertility.
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Affiliation(s)
- Marcy E. Richardson
- School of Medicine, Department of Reproductive Medicine, University of California, San Diego, 9500 Gilman Drive, MC 0695, La Jolla, CA 92093-0864, USA
| | - Andreas Bleiziffer
- Center for Reproductive Medicine and Andrology, University of Münster, Domagkstraße 11, D-48129 Münster, Germany
| | - Frank Tüttelmann
- Institute of Human Genetics, University of Münster, Vesaliusweg 12-14, D-48149 Münster, Germany
| | - Jörg Gromoll
- Center for Reproductive Medicine and Andrology, University of Münster, Domagkstraße 11, D-48129 Münster, Germany
| | - Miles F. Wilkinson
- School of Medicine, Department of Reproductive Medicine, University of California, San Diego, 9500 Gilman Drive, MC 0695, La Jolla, CA 92093-0864, USA
- Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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9
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MacLean JA, Hu Z, Welborn JP, Song HW, Rao MK, Wayne CM, Wilkinson MF. The RHOX homeodomain proteins regulate the expression of insulin and other metabolic regulators in the testis. J Biol Chem 2013; 288:34809-25. [PMID: 24121513 DOI: 10.1074/jbc.m113.486340] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Defects in cellular metabolism have been widely implicated in causing male infertility, but there has been little progress in understanding the underlying mechanism. Here we report that several key metabolism genes are regulated in the testis by Rhox5, the founding member of a large X-linked homeobox gene cluster. Among these Rhox5-regulated genes are insulin 2 (Ins2), resistin (Retn), and adiponectin (Adipoq), all of which encode secreted proteins that have profound and wide-ranging effects on cellular metabolism. The ability of Rhox5 to regulate their levels in the testis has the potential to dictate metabolism locally in this organ, given the existence of the blood-testes barrier. We demonstrate that Ins2 is a direct target of Rhox5 in Sertoli cells, and we show that this regulation is physiologically significant, because Rhox5-null mice fail to up-regulate Ins2 expression during the first wave of spermatogenesis and have insulin-signaling defects. We identify other Rhox family members that induce Ins2 transcription, define protein domains and homeodomain amino acid residues crucial for this property, and demonstrate that this regulation is conserved. Rhox5-null mice also exhibit altered expression of other metabolism genes, including those encoding the master transcriptional regulators of metabolism, PPARG and PPARGC1A, as well as SCD1, the rate-limiting enzyme for fatty acid metabolism. These results, coupled with the known roles of RHOX5 and its target metabolism genes in spermatogenesis in vivo, lead us to propose a model in which RHOX5 is a central transcription factor that promotes the survival of male germ cells via its effects on cellular metabolism.
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Affiliation(s)
- James A MacLean
- From the Department of Physiology, Southern Illinois University School of Medicine, Carbondale, Illinois 62901
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10
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Lee SE, Lee SY, Lee KA. Rhox in mammalian reproduction and development. Clin Exp Reprod Med 2013; 40:107-14. [PMID: 24179867 PMCID: PMC3811726 DOI: 10.5653/cerm.2013.40.3.107] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Revised: 09/10/2013] [Accepted: 09/10/2013] [Indexed: 01/06/2023] Open
Abstract
Homeobox genes play essential roles in embryonic development and reproduction. Recently, a large cluster of homeobox genes, reproductive homeobox genes on the X chromosome (Rhox) genes, was discovered as three gene clusters, α, β, and γ in mice. It was found that Rhox genes were selectively expressed in reproduction-associated tissues, such as those of the testes, epididymis, ovaries, and placenta. Hence, it was proposed that Rhox genes are important for regulating various reproductive features, especially gametogenesis in male as well as in female mammals. It was first determined that 12 Rhox genes are clustered into α (Rhox1-4), β (Rhox5-9), and γ (Rhox10-12) subclusters, and recently Rhox13 has also been found. At present, 33 Rhox genes have been identified in the mouse genome, 11 in the rat, and three in the human. Rhox genes are also responsible for embryonic development, with considerable amounts of Rhox expression in trophoblasts, placenta tissue, embryonic stem cells, and primordial germ cells. In this article we summarized the current understanding of Rhox family genes involved in reproduction and embryonic development and elucidated a previously unreported cell-specific expression in ovarian cells.
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Affiliation(s)
- Sang-Eun Lee
- Department of Biomedical Science, College of Life Science, CHA University, Seoul, Korea
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11
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Ohno R, Nakayama M, Naruse C, Okashita N, Takano O, Tachibana M, Asano M, Saitou M, Seki Y. A replication-dependent passive mechanism modulates DNA demethylation in mouse primordial germ cells. Development 2013; 140:2892-903. [PMID: 23760957 DOI: 10.1242/dev.093229] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Germline cells reprogramme extensive epigenetic modifications to ensure the cellular totipotency of subsequent generations and to prevent the accumulation of epimutations. Notably, primordial germ cells (PGCs) erase genome-wide DNA methylation and H3K9 dimethylation marks in a stepwise manner during migration and gonadal periods. In this study, we profiled DNA and histone methylation on transposable elements during PGC development, and examined the role of DNA replication in DNA demethylation in gonadal PGCs. CpGs in short interspersed nuclear elements (SINEs) B1 and B2 were substantially demethylated in migrating PGCs, whereas CpGs in long interspersed nuclear elements (LINEs), such as LINE-1, were resistant to early demethylation. By contrast, CpGs in both LINE-1 and SINEs were rapidly demethylated in gonadal PGCs. Four major modifiers of DNA and histone methylation, Dnmt3a, Dnmt3b, Glp and Uhrf1, were actively repressed at distinct stages of PGC development. DNMT1 was localised at replication foci in nascent PGCs, whereas the efficiency of recruitment of DNMT1 into replication foci was severely impaired in gonadal PGCs. Hairpin bisulphite sequencing analysis showed that strand-specific hemi-methylated CpGs on LINE-1 were predominant in gonadal PGCs. Furthermore, DNA demethylation in SINEs and LINE-1 was impaired in Cbx3-deficient PGCs, indicating abnormalities in G1 to S phase progression. We propose that PGCs employ active and passive mechanisms for efficient and widespread erasure of genomic DNA methylation.
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Affiliation(s)
- Rika Ohno
- Department of Bioscience, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
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12
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Brown RM, Davis MG, Hayashi K, MacLean JA. Regulated expression of Rhox8 in the mouse ovary: evidence for the role of progesterone and RHOX5 in granulosa cells. Biol Reprod 2013; 88:126. [PMID: 23536368 DOI: 10.1095/biolreprod.112.103267] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The gonadotropin surge is the essential trigger to stimulate ovulation and luteinization of ovarian follicles. While the hormone signals from the brain that initiate ovulation are known, the specific targets which regulate this process are not well known. In this study, we assessed the suitability of the Rhox homeobox gene cluster to serve as the master regulators of folliculogenesis. In superovulated (equine chorionic gonadotropin [eCG]/human chorionic gonadotropin [hCG]) mice, the Rhox genes exhibited four distinct windows of peak expression, suggesting that these genes may regulate specific events during the ovulatory cycle. Like many members of the cluster, Rhox8 mRNA and protein were induced by follicle stimulating hormone [FSH]/eCG in granulosa cells. However, Rhox8 displayed unique peak expression at 8 h post-hCG administration, implying it might be the lone member of the cluster regulated by progesterone. Subsequent promoter analysis in granulosa cells revealed relevant homeobox binding and progesterone response elements within Rhox8's 5'-flanking region. In superovulated mice, progesterone receptor (PGR) is recruited to the Rhox8 promoter, as assessed by chromatin immunoprecipitation. In Rhox5-null mice, Rhox8 mRNA was reduced at 2 h and 4 h post-hCG administration but recovered once the follicles passed the antral stage of development. Conversely, in progesterone receptor knockout mice, Rhox8 exhibited normal stimulation by eCG but failed to reach its peak mRNA level at 8 h post-hCG found in wild-type mice. This suggests a model in which Rhox8 transcription is dependent upon RHOX5 during early folliculogenesis and upon progesterone during the periovulatory window when RHOX5 normally wanes. In support of this model, transfection of RHOX5 and PGR expression plasmids stimulated, whereas dominant negative and mutant constructs inhibited, Rhox8 promoter activity.
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Affiliation(s)
- Raquel M Brown
- Department of Physiology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
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13
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Berletch JB, Deng X, Nguyen DK, Disteche CM. Female bias in Rhox6 and 9 regulation by the histone demethylase KDM6A. PLoS Genet 2013; 9:e1003489. [PMID: 23658530 PMCID: PMC3642083 DOI: 10.1371/journal.pgen.1003489] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 03/18/2013] [Indexed: 12/20/2022] Open
Abstract
The Rhox cluster on the mouse X chromosome contains reproduction-related homeobox genes expressed in a sexually dimorphic manner. We report that two members of the Rhox cluster, Rhox6 and 9, are regulated by de-methylation of histone H3 at lysine 27 by KDM6A, a histone demethylase with female-biased expression. Consistent with other homeobox genes, Rhox6 and 9 are in bivalent domains prior to embryonic stem cell differentiation and thus poised for activation. In female mouse ES cells, KDM6A is specifically recruited to Rhox6 and 9 for gene activation, a process inhibited by Kdm6a knockdown in a dose-dependent manner. In contrast, KDM6A occupancy at Rhox6 and 9 is low in male ES cells and knockdown has no effect on expression. In mouse ovary where Rhox6 and 9 remain highly expressed, KDM6A occupancy strongly correlates with expression. Our study implicates Kdm6a, a gene that escapes X inactivation, in the regulation of genes important in reproduction, suggesting that KDM6A may play a role in the etiology of developmental and reproduction-related effects of X chromosome anomalies.
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Affiliation(s)
- Joel B. Berletch
- Department of Pathology, School of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Xinxian Deng
- Department of Pathology, School of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Di Kim Nguyen
- Department of Pathology, School of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Christine M. Disteche
- Department of Pathology, School of Medicine, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, School of Medicine, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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14
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Song HW, Anderson RA, Bayne RA, Gromoll J, Shimasaki S, Chang RJ, Parast MM, Laurent LC, de Rooij DG, Hsieh TC, Wilkinson MF. The RHOX homeobox gene cluster is selectively expressed in human oocytes and male germ cells. Hum Reprod 2013; 28:1635-46. [PMID: 23482336 DOI: 10.1093/humrep/det043] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
STUDY QUESTION What human tissues and cell types express the X-linked reproductive homeobox (RHOX) gene cluster? SUMMARY ANSWER The RHOX homeobox genes and proteins are selectively expressed in germ cells in both the ovary and testis. WHAT IS KNOWN ALREADY The RHOX homeobox transcription factors are encoded by an X-linked gene cluster whose members are selectively expressed in the male and female reproductive tract of mice and rats. The Rhox genes have undergone strong selection pressure to rapidly evolve, making it uncertain whether they maintain their reproductive tissue-centric expression pattern in humans, an issue we address in this report. STUDY DESIGN, SIZE, DURATION We examined the expression of all members of the human RHOX gene cluster in 11 fetal and 8 adult tissues. The focus of our analysis was on fetal testes, where we evaluated 16 different samples from 8 to 20 weeks gestation. We also analyzed fixed sections from fetal testes, adult testes and adult ovaries to determine the cell type-specific expression pattern of the proteins encoded by RHOX genes. PARTICIPANTS/MATERIALS, SETTING, METHODS We used quantitative reverse transcription-polymerase chain reaction analysis to assay human RHOX gene expression. We generated antisera against RHOX proteins and used them for western blotting, immunohistochemical and immunofluorescence analyses of RHOXF1 and RHOXF2/2B protein expression. MAIN RESULTS AND THE ROLE OF CHANCE We found that the RHOXF1 and RHOXF2/2B genes are highly expressed in the testis and exhibit low or undetectable expression in most other organs. Using RHOXF1- and RHOXF2/2B-specific antiserum, we found that both RHOXF1 and RHOXF2/2B are primarily expressed in germ cells in the adult testis. Early stage germ cells (spermatogonia and early spermatocytes) express RHOXF2/2B, while later stage germ cells (pachytene spermatocytes and round spermatids) express RHOXF1. Both RHOXF1 and RHOXF2/2B are expressed in prespermatogonia in human fetal testes. Consistent with this, RHOXF1 and RHOXF2/2B mRNA expression increases in the second trimester during fetal testes development when gonocytes differentiate into prespermatogonia. In the human adult ovary, we found that RHOXF1 and RHOXF2/2B are primarily expressed in oocytes. LIMITATIONS, REASONS FOR CAUTION While the average level of expression of RHOX genes was low or undetectable in all 19 human tissues other than testes, it is still possible that RHOX genes are highly expressed in a small subset of cells in some of these non-testicular tissues. As a case in point, we found that RHOX proteins are highly expressed in oocytes within the human ovary, despite low levels of RHOX mRNA in the whole ovary. WIDER IMPLICATIONS OF THE FINDINGS The cell type-specific and developmentally regulated expression pattern of the RHOX transcription factors suggests that they perform regulatory functions during human fetal germ cell development, spermatogenesis and oogenesis. Our results also raise the possibility that modulation of RHOX gene levels could correct some cases of human infertility and that their encoded proteins are candidate targets for contraceptive drug design.
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Affiliation(s)
- H W Song
- Department of Reproductive Medicine, School of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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15
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Miles DC, Wakeling SI, Stringer JM, van den Bergen JA, Wilhelm D, Sinclair AH, Western PS. Signaling through the TGF beta-activin receptors ALK4/5/7 regulates testis formation and male germ cell development. PLoS One 2013; 8:e54606. [PMID: 23342175 PMCID: PMC3546992 DOI: 10.1371/journal.pone.0054606] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 12/14/2012] [Indexed: 01/19/2023] Open
Abstract
The developing testis provides an environment that nurtures germ cell development, ultimately ensuring spermatogenesis and fertility. Impacts on this environment are considered to underlie aberrant germ cell development and formation of germ cell tumour precursors. The signaling events involved in testis formation and male fetal germ cell development remain largely unknown. Analysis of knockout mice lacking single Tgfβ family members has indicated that Tgfβ's are not required for sex determination. However, due to functional redundancy, it is possible that additional functions for these ligands in gonad development remain to be discovered. Using FACS purified gonadal cells, in this study we show that the genes encoding Activin's, TGFβ's, Nodal and their respective receptors, are expressed in sex and cell type specific patterns suggesting particular roles in testis and germ cell development. Inhibition of signaling through the receptors ALK4, ALK5 and ALK7, and ALK5 alone, demonstrated that TGFβ signaling is required for testis cord formation during the critical testis-determining period. We also show that signaling through the Activin/NODAL receptors, ALK4 and ALK7 is required for promoting differentiation of male germ cells and their entry into mitotic arrest. Finally, our data demonstrate that Nodal is specifically expressed in male germ cells and expression of the key pluripotency gene, Nanog was significantly reduced when signaling through ALK4/5/7 was blocked. Our strategy of inhibiting multiple Activin/NODAL/TGFβ receptors reduces the functional redundancy between these signaling pathways, thereby revealing new and essential roles for TGFβ and Activin signaling during testis formation and male germ cell development.
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Affiliation(s)
- Denise C. Miles
- Centre for Reproduction and Development, Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia
| | - Stephanie I. Wakeling
- Centre for Reproduction and Development, Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia
| | - Jessica M. Stringer
- Centre for Reproduction and Development, Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia
| | - Jocelyn A. van den Bergen
- Department of Paediatrics, University of Melbourne, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Dagmar Wilhelm
- Department of Anatomy and Developmental Biology, Monash University, Clayton, Victoria, Australia
| | - Andrew H. Sinclair
- Department of Paediatrics, University of Melbourne, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Patrick S. Western
- Centre for Reproduction and Development, Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia
- * E-mail:
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16
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Celebi C, van Montfoort A, Skory V, Kieffer E, Kuntz S, Mark M, Viville S. Tex 19 paralogs exhibit a gonad and placenta-specific expression in the mouse. J Reprod Dev 2012; 58:360-5. [PMID: 22447323 DOI: 10.1262/jrd.11-047k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have previously suggested that TEX19, a mammalian-specific protein of which two paralogs exist in rodents, could be implicated in stem cell self-renewal and pluripotency. We have established here the expression profiles of Tex19.1 and Tex19.2 during mouse development and adulthood. We show that both genes are coexpressed in the ectoderm and then in primordial germ cells (PGCs). They are also coexpressed in the testis from embryonic day 13.5 to adulthood, whereas only Tex19.1 transcripts are detected in the developing and adult ovary as well as in the placenta and its precursor tissue, the ectoplacental cone. The presence of both Tex19.1 and Tex19.2 in PGCs, gonocytes and spermatocytes opens the possibility that these two genes could play redundant functions in male germ cells. Furthermore, the placental expression of Tex19.1 can explain why Tex19.1 knockout mice show embryonic lethality, in addition to testis defects.
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Affiliation(s)
- Catherine Celebi
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), U964/Centre National de Recherche Scientifique (CNRS) UMR 1704/Université de Strasbourg, 67404 Illkirch, France
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17
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Song HW, Dann CT, McCarrey JR, Meistrich ML, Cornwall GA, Wilkinson MF. Dynamic expression pattern and subcellular localization of the Rhox10 homeobox transcription factor during early germ cell development. Reproduction 2012; 143:611-24. [PMID: 22393026 DOI: 10.1530/rep-11-0479] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Homeobox genes encode transcription factors that regulate diverse developmental events. The largest known homeobox gene cluster - the X-linked mouse reproductive homeobox (Rhox) cluster - harbors genes whose expression patterns and functions are largely unknown. Here, we report that a member of this cluster, Rhox10, is expressed in male germ cells. Rhox10 is highly transcribed in spermatogonia in vivo and is upregulated in response to the differentiation-inducing agent retinoic acid in vitro. Using a specific RHOX10 antiserum that we generated, we found that RHOX10 protein is selectively expressed in fetal gonocytes, germline stem cells, spermatogonia, and early spermatocytes. RHOX10 protein undergoes a dramatic shift in subcellular localization as germ cells progress from mitotically arrested gonocytes to mitotic spermatogonia and from mitotic spermatogonia to early meiotic spermatocytes, consistent with RHOX10 performing different functions in these stages.
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Affiliation(s)
- Hye-Won Song
- Department of Reproductive Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093, USA
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18
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Le Bouffant R, Souquet B, Duval N, Duquenne C, Hervé R, Frydman N, Robert B, Habert R, Livera G. Msx1 and Msx2 promote meiosis initiation. Development 2011; 138:5393-402. [PMID: 22071108 DOI: 10.1242/dev.068452] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The mechanisms regulating germ line sex determination and meiosis initiation are poorly understood. Here, we provide evidence for the involvement of homeobox Msx transcription factors in foetal meiosis initiation in mammalian germ cells. Upon meiosis initiation, Msx1 and Msx2 genes are strongly expressed in the foetal ovary, possibly stimulated by soluble factors found there: bone morphogenetic proteins Bmp2 and Bmp4, and retinoic acid. Analysis of Msx1/Msx2 double mutant embryos revealed a majority of undifferentiated germ cells remaining in the ovary and, importantly, a decrease in the number of meiotic cells. In vivo, the Msx1/Msx2 double-null mutation prevented full activation of Stra8, a gene required for meiosis. In F9 cells, Msx1 can bind to Stra8 regulatory sequences and Msx1 overexpression stimulates Stra8 transcription. Collectively, our data demonstrate for the first time that some homeobox genes are required for meiosis initiation in the female germ line.
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Affiliation(s)
- Ronan Le Bouffant
- CEA, DSV/iRCM/SCSR/LDG, Laboratoire de Développement des Gonades, Unité Cellules Souches et Radiation, F-92265 Fontenay aux Roses, France
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19
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Rapid evolution and copy number variation of primate RHOXF2, an X-linked homeobox gene involved in male reproduction and possibly brain function. BMC Evol Biol 2011; 11:298. [PMID: 21988730 PMCID: PMC3214919 DOI: 10.1186/1471-2148-11-298] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Accepted: 10/12/2011] [Indexed: 11/30/2022] Open
Abstract
Background Homeobox genes are the key regulators during development, and they are in general highly conserved with only a few reported cases of rapid evolution. RHOXF2 is an X-linked homeobox gene in primates. It is highly expressed in the testicle and may play an important role in spermatogenesis. As male reproductive system is often the target of natural and/or sexual selection during evolution, in this study, we aim to dissect the pattern of molecular evolution of RHOXF2 in primates and its potential functional consequence. Results We studied sequences and copy number variation of RHOXF2 in humans and 16 nonhuman primate species as well as the expression patterns in human, chimpanzee, white-browed gibbon and rhesus macaque. The gene copy number analysis showed that there had been parallel gene duplications/losses in multiple primate lineages. Our evidence suggests that 11 nonhuman primate species have one RHOXF2 copy, and two copies are present in humans and four Old World monkey species, and at least 6 copies in chimpanzees. Further analysis indicated that the gene duplications in primates had likely been mediated by endogenous retrovirus (ERV) sequences flanking the gene regions. In striking contrast to non-human primates, humans appear to have homogenized their two RHOXF2 copies by the ERV-mediated non-allelic recombination mechanism. Coding sequence and phylogenetic analysis suggested multi-lineage strong positive selection on RHOXF2 during primate evolution, especially during the origins of humans and chimpanzees. All the 8 coding region polymorphic sites in human populations are non-synonymous, implying on-going selection. Gene expression analysis demonstrated that besides the preferential expression in the reproductive system, RHOXF2 is also expressed in the brain. The quantitative data suggests expression pattern divergence among primate species. Conclusions RHOXF2 is a fast-evolving homeobox gene in primates. The rapid evolution and copy number changes of RHOXF2 had been driven by Darwinian positive selection acting on the male reproductive system and possibly also on the central nervous system, which sheds light on understanding the role of homeobox genes in adaptive evolution.
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20
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The rhox homeobox gene cluster is imprinted and selectively targeted for regulation by histone h1 and DNA methylation. Mol Cell Biol 2011; 31:1275-87. [PMID: 21245380 DOI: 10.1128/mcb.00734-10] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Histone H1 is an abundant and essential component of chromatin whose precise role in regulating gene expression is poorly understood. Here, we report that a major target of H1-mediated regulation in embryonic stem (ES) cells is the X-linked Rhox homeobox gene cluster. To address the underlying mechanism, we examined the founding member of the Rhox gene cluster-Rhox5-and found that its distal promoter (Pd) loses H1, undergoes demethylation, and is transcriptionally activated in response to loss of H1 genes in ES cells. Demethylation of the Pd is required for its transcriptional induction and we identified a single cytosine in the Pd that, when methylated, is sufficient to inhibit Pd transcription. Methylation of this single cytosine prevents the Pd from binding GA-binding protein (GABP), a transcription factor essential for Pd transcription. Thus, H1 silences Rhox5 transcription by promoting methylation of one of its promoters, a mechanism likely to extend to other H1-regulated Rhox genes, based on analysis of ES cells lacking DNA methyltransferases. The Rhox cluster genes targeted for H1-mediated transcriptional repression are also subject to another DNA methylation-regulated process: Xp imprinting. Remarkably, we found that only H1-regulated Rhox genes are imprinted, not those immune to H1-mediated repression. Together, our results indicate that the Rhox gene cluster is a major target of H1-mediated transcriptional repression in ES cells and that H1 is a candidate to have a role in Xp imprinting.
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21
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Abstract
Homeobox genes encode transcription factors that have crucial roles in embryogenesis. A recently discovered set of homeobox genes--the Rhox genes--are expressed during both embryogenesis and in adult reproductive tissues. The 33 known mouse Rhox genes are clustered together in a single region on the X chromosome, while likely descendents of the primodial Rhox cluster, Arx and Esx1, have moved to other positions on the X chromosome. Here, we summarize what is known about the regulation and function of Rhox cluster and Rhox-related genes during embryogenesis and gametogenesis. The founding member of the Rhox gene cluster--Rhox5 (previously known as Pem)--has been studied in the most depth and thus is the focus of this review. We also discuss the unusually rapid evolution of the Rhox gene cluster.
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Affiliation(s)
- James A MacLean
- Department of Physiology, School of Medicine, Southern Illinois University, Carbondale, IL 62901, USA
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22
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Bonaparte E, Moretti M, Colpi GM, Nerva F, Contalbi G, Vaccalluzzo L, Tabano S, Grati FR, Gazzano G, Sirchia SM, Simoni G, Gallina A, Miozzo M. ESX1 gene expression as a robust marker of residual spermatogenesis in azoospermic men. Hum Reprod 2010; 25:1398-403. [DOI: 10.1093/humrep/deq074] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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23
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Hu Z, Dandekar D, O'Shaughnessy PJ, De Gendt K, Verhoeven G, Wilkinson MF. Androgen-induced Rhox homeobox genes modulate the expression of AR-regulated genes. Mol Endocrinol 2009; 24:60-75. [PMID: 19901196 DOI: 10.1210/me.2009-0303] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Rhox5, the founding member of the reproductive homeobox on the X chromosome (Rhox) gene cluster, encodes a homeodomain-containing transcription factor that is selectively expressed in Sertoli cells, where it promotes the survival of male germ cells. To identify Rhox5-regulated genes, we generated 15P-1 Sertoli cell clones expressing physiological levels of Rhox5 from a stably transfected expression vector. Microarray analysis identified many genes altered in expression in response to Rhox5, including those encoding proteins controlling cell cycle regulation, apoptosis, metabolism, and cell-cell interactions. Fifteen of these Rhox5-regulated genes were chosen for further analysis. Analysis of Rhox5-null male mice indicated that at least nine of these are Rhox5-regulated in the testes in vivo. Many of them have distinct postnatal expression patterns and are regulated by Rhox5 at different postnatal time points. Most of them are expressed in Sertoli cells, indicating that they are candidates to be directly regulated by Rhox5. Transfection analysis with expression vectors encoding different mouse and human Rhox family members revealed that the regulatory response of a subset of these Rhox5-regulated genes is both conserved and redundant. Given that Rhox5 depends on androgen receptor (AR) for expression in Sertoli cells, we examined whether some Rhox5-regulated genes are also regulated by AR. We provide several lines of evidence that this is the case, leading us to propose that RHOX5 serves as a key intermediate transcription factor that directs some of the actions of AR in the testes.
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Affiliation(s)
- Zhiying Hu
- Department of Biochemistry & Molecular Biology, University of Texas M D Anderson Cancer Center, Houston, Texas 77030, USA
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24
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Abstract
Germ cells undergo comprehensive epigenetic reprogramming toward acquiring fitness for pluripotency and totipotency. Notably, the full extent of the epigenetic reprogramming experienced by germ cells remains unmatched by attempts to experimentally restore pluripotency in somatic cells. We propose that the defects present in experimentally generated cells are corrected upon differentiation into the germ cell lineage, as has been observed in cases of germline transmission. Unraveling the mechanisms responsible for germ cell-specific epigenetic reprogramming will likely have important implications for both basic and clinical stem cell research.
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Affiliation(s)
- Katsuhiko Hayashi
- Wellcome Trust Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
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25
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Tanaka TS. Transcriptional heterogeneity in mouse embryonic stem cells. Reprod Fertil Dev 2009; 21:67-75. [PMID: 19152747 DOI: 10.1071/rd08219] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The embryonic stem (ES) cell is a stem cell derived from early embryos that can indefinitely repeat self-renewing cell division cycles as an undifferentiated cell in vitro and give rise to all specialised cell types in the body. However, manipulating ES cell differentiation in vitro is a challenge due to, at least in part, heterogeneous gene induction. Recent experimental evidence has demonstrated that undifferentiated mouse ES cells maintained in culture exhibit heterogeneous expression of Dppa3, Nanog, Rex1, Pecam1 and Zscan4 as well as genes (Brachyury/T, Rhox6/9 and Twist2) normally expressed in specialised cell types. The Nanog-negative, Rex1-negative or T-positive ES cell subpopulation has a unique differentiation potential. Thus, studying the mechanism that generates ES cell subpopulations will improve manipulation of ES cell fate and help our understanding of the nature of embryonic development.
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Affiliation(s)
- Tetsuya S Tanaka
- Department of Animal Sciences, Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1207 West Gregory Drive, Urbana, IL 61801, USA.
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26
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Abstract
Although it has been thought that female mammals develop all the eggs they will ever have by the time they are born, new research suggesting otherwise has now sparked a debate.
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Affiliation(s)
- Teresa K Woodruff
- Watkins Professor of Obstetrics and Gynecology in the Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, 303 East Superior, Lurie 10-117, Chicago, Illinois 60611-3015, USA
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