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Male Germ Cells (male + germ_cell)
Selected AbstractsErasure of the paternal transcription program during spermiogenesis: The first step in the reprogramming of sperm chromatin for zygotic developmentDEVELOPMENTAL DYNAMICS, Issue 5 2008Junke Zheng Abstract Male germ cells possess a unique epigenetic program and express a male-specific transcription profile. However, when its chromatin is passed onto the zygote, it expresses an transcription/epigenetic program characteristic of the zygote. The mechanism underlying this reprogramming process is not understood at present. In this study, we show that an extensive range of chromatin factors (CFs), including essential transcription factors and regulators, remodeling factors, histone deacetylases, heterochromatin-binding proteins, and topoisomerases, were removed from chromatin during spermiogenesis. This process will erase the paternal epigenetic program to generate a relatively naive chromatin, which is likely to be essential for installation of the zygotic developmental program after fertilization. We have also showed that transcription termination in male germ cells was temporally correlated with CF dissociation. A genome-wide CF dissociation will inevitably disassemble the transcription apparatus and regulatory mechanism and lead to transcription silence. Based on data presented in this and previous studies (Sun et al., Cell Research [2007] 17:117,134), we propose that paternal-zygotic transcription reprogramming begins with a genome-wide CF dissociation to erase the existing transcription program in later stages of spermatogenesis. This will be followed by assembling of the zygotic equivalent after fertilization. The transcription/epigenetic program of the male germ cell is transformed into a zygotic one using an erase-and-rebuild strategy similar to that used in the maternal-zygotic transition. It is also noted that transcription is terminated long after meiosis is completed and before chromatin becomes highly condensed during spermatogenesis. The temporal order of these events suggests that transcription silence does not have to be coupled to meiosis or chromatin condensation. Developmental Dynamics 237:1463-1476, 2008. © 2008 Wiley-Liss, Inc. [source] Prenatal development of murine gonads with special reference to germ cell differentiation: a morphological and immunohistochemical studyANDROLOGIA, Issue 3 2007A. E. Zayed Summary The prenatal differentiation of male and female gonads of the mouse was investigated both morphologically and immunohistochemically. Sexual dimorphism could be detected as early as 12 days post-coitum (dpc) by the appearance of the primary elements of the tunica albuginea and positive immunoreactivity for anti-Muellerian hormone in the Sertoli cells of the male gonad. Male germ cells passed two waves of mitotic activity, a first wave between 12 and 14 dpc, which is followed by apoptosis of the old germ cell generation, and a second wave between 17 and 20 dpc. Oct-4 was expressed as a juxtanuclear ring in the cytoplasm of germ cells up to 17 dpc. Subsequently, it was down-regulated and completely disappeared in 20 dpc full-term fetuses. By contrast, M2A antigen revealed only a weak immunoreaction in some germ cells of 14 dpc gonads, but exhibited strong signals in all germ cells of 20 dpc full-term fetuses. Therefore, we postulate that, in the mouse, prenatal germ cells represent two populations: the first is immunopositive for Oct-4 and disappeared in full-term fetuses, whereas the second appeared in 14 dpc and is immunopositive for M2A antigen. [source] Erasure of the paternal transcription program during spermiogenesis: The first step in the reprogramming of sperm chromatin for zygotic developmentDEVELOPMENTAL DYNAMICS, Issue 5 2008Junke Zheng Abstract Male germ cells possess a unique epigenetic program and express a male-specific transcription profile. However, when its chromatin is passed onto the zygote, it expresses an transcription/epigenetic program characteristic of the zygote. The mechanism underlying this reprogramming process is not understood at present. In this study, we show that an extensive range of chromatin factors (CFs), including essential transcription factors and regulators, remodeling factors, histone deacetylases, heterochromatin-binding proteins, and topoisomerases, were removed from chromatin during spermiogenesis. This process will erase the paternal epigenetic program to generate a relatively naive chromatin, which is likely to be essential for installation of the zygotic developmental program after fertilization. We have also showed that transcription termination in male germ cells was temporally correlated with CF dissociation. A genome-wide CF dissociation will inevitably disassemble the transcription apparatus and regulatory mechanism and lead to transcription silence. Based on data presented in this and previous studies (Sun et al., Cell Research [2007] 17:117,134), we propose that paternal-zygotic transcription reprogramming begins with a genome-wide CF dissociation to erase the existing transcription program in later stages of spermatogenesis. This will be followed by assembling of the zygotic equivalent after fertilization. The transcription/epigenetic program of the male germ cell is transformed into a zygotic one using an erase-and-rebuild strategy similar to that used in the maternal-zygotic transition. It is also noted that transcription is terminated long after meiosis is completed and before chromatin becomes highly condensed during spermatogenesis. The temporal order of these events suggests that transcription silence does not have to be coupled to meiosis or chromatin condensation. Developmental Dynamics 237:1463-1476, 2008. © 2008 Wiley-Liss, Inc. [source] MSY2 and polypyrimidine tract binding protein 2 stabilize mRNAs in the mammalian testisINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 5 2008Mingang Xu Summary MSY2 is a highly conserved and abundant DNA/RNA-binding protein that functions as a global stabilizer/translational suppressor of mRNAs in male germ cells. The polypyrimidine tract binding protein, PTBP2, is an RNA-binding protein that splices nuclear transcripts and stabilizes specific mRNAs in the cytoplasm. The mechanisms whereby MSY2 selects and stabilizes a large group of male germ cell mRNAs and PTBP2 stabilizes specific mRNAs such as the phosphoglycerate kinase 2 mRNA in the testis and in transfected cells will be discussed. [source] Aromatase and oestrogens in human male germ cellsINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 5 2005SOPHIE LAMBARD Summary The mammalian testis serves two main functions: production of spermatozoa and synthesis of steroids, among them oestrogens are the end products obtained from the irreversible transformation of androgens by aromatase (P450arom). Up today P450arom has been demonstrated in male germ cells of all mammals so far studied (mice, rat, bank vole, bear, monkey). In man Leydig cells and immature germ cells as well as ejaculated spermatozoa express a biologically active aromatase. Moreover germ cells and spermatozoa contain oestrogen receptors (ER- , and ER- ,) and it is of note that a truncated form of ER- , is present in spermatozoa. These observations clearly suggest that oestrogens are likely concerned in various stages of male germ cell development. [source] Specialized rules of gene transcription in male germ cells: the CREM paradigm*INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 6 2004Lucia Monaco Summary Specialized transcription complexes that coordinate the differentiation programme of spermatogenesis have been found in germ cells, which display specific differences in the components of the general transcription machinery. The TATA-binding protein family and its associated cofactors, for example, show upregulated expression in testis. In this physiological context, transcriptional control mediated by the activator cAMP response element modulator (CREM) represents an established paradigm. Somatic cell activation by CREM requires its phosphorylation at a unique regulatory site (Ser117) and subsequent interaction with the ubiquitous coactivator CREB-binding protein. In testis, CREM transcriptional activity is controlled through interaction with a tissue-specific partner, activator of CREM in the testis (ACT), which confers a powerful, phosphorylation-independent activation capacity. The function of ACT was found to be regulated by the testis-specific kinesin KIF17b. Here we discuss some aspects of the testis-specific transcription machinery, whose function is essential for the process of spermatogenesis. [source] The A-type cyclins and the meiotic cell cycle in mammalian male germ cellsINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 4 2004Debra J. Wolgemuth Summary There are two mammalian A-type cyclins, cyclin Al and A2. While cyclin A1 is limited to male germ cells, cyclin A2 is widely expressed. Cyclin A2 promotes both Gl/S and G2/M transitions in somatic cells and cyclin A2-deficient mice are early embryonic lethal. We have shown that cyclin Al is essential for passage of spermatocytes into meiosis I (MI) by generating mice null for the cyclin A1 gene Ccna1. Both Ccna1,/, males and females were healthy but the males were sterile because of a cell cycle arrest before MI. This arrest was associated with desynapsis abnormalities, low M-phase promoting factor activity, and apoptosis. We have now determined that human cyclin A1 is expressed in similar stages of spermatogenesis and are exploring its role in human male infertility and whether it may be a novel target for new approaches for male contraception. [source] L1 elements, processed pseudogenes and retrogenes in mammalian genomesIUBMB LIFE, Issue 12 2006Wenyong Ding Abstract Long interspersed nuclear elements 1 (L1 elements or LINE1) are the most active autonomous retrotransposons in mammalian genomes. In addition to L1 elements themselves, other protein-coding mRNAs can also be reverse transcribed and integrated into the genome through the L1-mediated retrotransposition, leading to the formation of processed pseudogenes (PPs) and retrogenes, both of which are characterized by the lack of introns and the presence of a 3' polyA tract and flanking direct repeats. PPs are unable to encode a functional protein and have accumulated frameshift mutations and premature stop codons during evolution. A few of PPs are transcriptionally active. Retrogenes preserve undisrupted coding frames and are capable of encoding a functional protein that is identical or nearly identical to that of the progenitor gene. There is a significant excess of retrogenes that originate from the X chromosome and are retrotransposed into autosomes, and most of these retrogenes are specially expressed in male germ cells, suggesting the inactivation of X-linked genes during male meiosis provides a strong selection pressure on retrogenes originating from the X chromosome. iubmb Life, 58: 677-685, 2006 [source] Novel identification of peripheral dopaminergic D2 receptor in male germ cells,JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2007Carola Otth Abstract Dopamine is a recognized modulator in the central nervous system (CNS) and peripheral organ functions. The presence of peripheral dopamine receptors outside the CNS has suggested an intriguing interaction between the nervous system and other functional systems, such as the reproductive system. In the present study we analyzed the expression of D2R receptors in rat testis, rat spermatogenic cells and spermatozoa, in different mammals. The RT-PCR analysis of rat testis mRNA showed specific bands corresponding to the two dopamine receptor D2R (L and S) isoforms previously described in the brain. Using Western blot analysis, we confirmed that the protein is present in rat testis, isolated spermatogenic cells and also in spermatozoa of a range of different mammals, such as rat, mouse, bull, and human. The immunohistochemistry analysis of rat adult testis showed that the receptor was expressed in all germ cells (pre- and post-meiotic phase) of the tubule with staining predominant in spermatogonia. Confocal analysis by indirect immunofluorescence revealed that in non-capacitated spermatozoa of rat, mouse, bull, and human, D2R is mainly localized in the flagellum, and is also observed in the acrosomal region of the sperm head (except in human spermatozoa). Our findings demonstrate that the two D2 receptor isoforms are expressed in rat testis and that the receptor protein is present in different mammalian spermatozoa. The presence of D2R receptors in male germ cells implies new and unsuspected roles for dopamine signaling in testicular and sperm physiology. J. Cell. Biochem. 100: 141,150, 2007. © 2006 Wiley-Liss, Inc. [source] Anti-aging activity of the Ink4/Arf locusAGING CELL, Issue 2 2009Ander Matheu Summary The proteins encoded by the Ink4/Arf locus, p16Ink4a, p19Arf and p15Ink4b are major tumour suppressors that oppose aberrant mitogenic signals. The expression levels of the locus are progressively increased during aging and genome-wide association studies have linked the locus to a number of aging-associated diseases and frailty in humans. However, direct measurement of the global impact of the Ink4/Arf locus on organismal aging and longevity was lacking. In this work, we have examined the fertility, cancer susceptibility, aging and longevity of mice genetically modified to carry one (Ink4/Arf -tg) or two (Ink4/Arf -tg/tg) intact additional copies of the locus. First, increased gene dosage of Ink4/Arf impairs the production of male germ cells, and in the case of Ink4/Arf -tg/tg mice results in a Sertoli cell-only-like syndrome and a complete absence of sperm. Regarding cancer, there is a lower incidence of aging-associated cancer proportional to the Ink4/Arf gene dosage. Interestingly, increased Ink4/Arf gene dosage resulted in lower scores in aging markers and in extended median longevity. The increased survival was also observed in cancer-free mice indicating that cancer protection and delayed aging are separable activities of the Ink4/Arf locus. In contrast to these results, mice carrying one or two additional copies of the p53 gene (p53 -tg and p53 -tg/tg) had a normal longevity despite their increased cancer protection. We conclude that the Ink4/Arf locus has a global anti-aging effect, probably by favouring quiescence and preventing unnecessary proliferation. [source] Expression of zinc finger protein 105 in the testis and its role in male fertilityMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 6 2010Huaxin Zhou Using an in silico approach, we identified a putative zinc finger domain-containing transcription factor (zinc finger protein 105, ZFP105) enriched in the adult mouse testis. RT-PCR analyses showed that Zfp105 was indeed highly expressed in adult mouse testis and that its expression was regulated during postnatal development. To further characterize Zfp105 expression, we generated a Zfp105:,-galactosidase (LacZ) knock-in reporter mouse line (Zfp105LacZ/+) in which a Zfp105:LacZ fusion gene was expressed. Whole-mount LacZ analyses of adult Zfp105LacZ/+ tissues showed robust LacZ staining in the testis, very weak staining in the ovary, and no staining in the spleen, liver, kidney, heart, lung, thymus, adrenal gland, uterus, or oviduct. Sectional LacZ staining showed that ZFP105 was highly expressed in pachytene spermatocytes. ZNF35, the human ortholog of Zfp105, was also highly expressed in human testis. Immunofluorescence analysis showed that ZNF35 was located primarily in the cytoplasm of male germ cells. More importantly, reduced male fertility was observed in adult Zfp105LacZ/LacZ mice. Histological studies showed the presence of undifferentiated spermatogenic cells in the lumen of seminiferous tubules at stage VII and in the epididymal lumen of adult Zfp105LacZ/LacZ mice. Taken together, our results suggest that ZFP105 is a male germ-cell factor and plays a role in male reproduction. Mol. Reprod. Dev. 77: 511,520, 2010. © 2010 Wiley-Liss, Inc. [source] A novel group of multi-GAP-domain proteinsMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 10 2008Yibing Ruan Abstract The Rho GTPase-activating proteins (RhoGAPs) play an essential role in regulating various cellular processes. Rat tGAP1 is the first reported protein that has multiple GAP domains. It is exclusively expressed in male germ cells. However, tGAP1 does not possess GAP activities in vitro. No tGAP1 homology has been identified in other species. In this study, we searched the genomic databases and identified many genes whose protein products possess 2,4 GAP domains in rat, mouse and dog. These genes all showed sequence similarity to tGAP1. The rat tGAP gene loci all locate on chromosome 2 and are all expressed in testes in RT-PCR analysis. The mouse tGAP gene loci also clustered on chromosome 3 but RT-PCR analysis showed most are pseudogene loci. Multiple sequence alignment showed that many conserved residues of the "arginine finger" motif within the GAP domains of predicted tGAP proteins have mutated, suggesting that tGAP proteins do not possess GAP activity. We also elucidated the evolutionary relations among the rat tGAP genes. Based on the phylogenetic analysis data, we proposed that tGAP genes and Arhgap20 genes have a common ancestor. Mol. Reprod. Dev. 75: 1578,1589 © 2008 Wiley-Liss, Inc. [source] The transcription factor CREM, and cAMP regulate promoter activity of the Na,K-ATPase ,4 isoformMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 11 2006Marianna Rodova Abstract The Na,K-ATPase is an essential enzyme of the plasma membrane that plays a key role in numerous cell processes that depend on the transcellular gradients of Na+ and K+. Among the various isoforms of the catalytic subunit of the Na,K-ATPase, ,4 exhibits the most limited pattern of expression, being restricted to male germ cells. Activity of ,4 is essential for sperm function, and ,4 is upregulated during spermatogenesis. The present study addressed the transcriptional control of the human Na,K-ATPase ,4 gene, ATP1A4. We describe that a 5, untranslated region of the ATP1A4 gene (designated ,339/+480 based on the ATP1A4 transcription initiation site) has promoter activity in luciferase reporter assays. Computer analysis of this promoter region revealed consensus sites (CRE) for the cyclic AMP (cAMP) response element modulator (CREM). Accordingly, dibutyryl cAMP (db-cAMP) and ectopic expression of CREM,, a testis specific splice variant of CREM were able to activate the ATP1A4 promoter driven expression of luciferase in HEK 293 T, JEG-3 and GC-1 cells. Further characterization of the effect of db-cAMP and CREM, on deleted constructs of the ATP1A4 promoter (,339/+80, and +25/+480), and on the ,339/+480 region carrying mutations in the CRE sites showed that db-cAMP and CREM, effect required the CRE motif located 263 bp upstream the transcription initiation site. EMSA experiments confirmed the CRE sequence as a bonafide CREM, binding site. These results constitute the first demonstration of the transcriptional control of ATP1A4 gene expression by cAMP and by CREM,, a transcription factor essential for male germ cell gene expression. Mol. Reprod. Dev. 73: 1435,1447, 2006. © 2006 Wiley-Liss, Inc. [source] Autoinhibitory regulation of soluble adenylyl cyclaseMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 3 2006James A. Chaloupka Abstract Soluble adenylyl cyclase is an evolutionarily conserved bicarbonate sensor that plays a crucial role in cAMP dependent processes that occur during mammalian fertilization. sAC protein is expressed at the highest levels in male germ cells, and is found to occur as one of two known isoforms: a truncated protein (sACt) that consists almost exclusively of the two conserved catalytic domains (C1 and C2), and a full-length form (sACfl) that contains an additional noncatalytic C-terminal region. Several studies suggested sACt was more active than sACfl. We now demonstrate that the specific activity of sACt is at least 10-fold higher than the specific activity of sACfl. Using deletion analysis and a novel genetic screen to identify activating mutations, we uncovered an autoinhibitory region just C-terminal to the C2 domain. Kinetic analysis of purified recombinant sAC revealed this autoinhibitory domain functions to lower the enzyme's Vmax without altering its affinity for substrate or regulation by any of the known modulators of sAC activity. Our results identify an additional regulatory mechanism specific to the sACfl isoform. Mol. Reprod. Dev. © 2005 Wiley-Liss, Inc. [source] Expression of Serpinb6 serpins in germ and somatic cells of mouse gonads,MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 1 2006Yves Charron Abstract The serpin superfamily of serine protease inhibitors is implicated in the regulation of numerous physiological processes. In mice, Spi3/Serpinb6 has a broad tissue distribution. We have investigated the expression of Serpinb6 family members in embryonic and adult gonads. In male and female mice, Spi3/Serpinb6 and NK13/Serpinb6b were expressed in developing gonads and in both somatic and germ cells of adult gonads. By contrast, gonadal expression of Spi3C/Serpinb6c was sexually dimorphic and restricted to male germ cells and female somatic cells. These observations raise the question of the possible role(s) of the Serpinb6 family members in gonad development, gametogenesis, and/or fertilization. Mol. Reprod. Dev. © 2005 Wiley-Liss, Inc. [source] Rat Spag5 associates in somatic cells with endoplasmic reticulum and microtubules but in spermatozoa with outer dense fibersMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 1 2006Carolyn J. Fitzgerald Abstract The leucine zipper motif has been identified as an important and specific interaction motif used by various sperm tail proteins that localize to the outer dense fibers. We had found that rat Odf1, a major integral ODF protein, utilizes its leucine zipper to associate with Odf2, another major ODF protein, Spag4 which localizes to the interface between ODF and axonemal microtubule doublets, and Spag5. The rat Spag5 sequence indicated a close relationship with human Astrin, a microtubule-binding spindle protein suggesting that Spag5, like Spag4, may associate with the sperm tail axoneme. RT PCR assays indicated expression of Spag5 in various tissues and in somatic cells Spag5 localizes to endoplasmic reticulum and microtubules, as expected for an Astrin orthologue. MT binding was confirmed both in vivo and in in vitro MT-binding assays: somatic cells contain a 58 kDa MT-associated Spag5 protein. Western blotting assays of rat somatic cells and male germ cells at different stages of development using anti-Spag5 antibodies demonstrated that the protein expression pattern changes during spermatogenesis and that sperm tails contain a 58 kDa Spag5 protein. Use of affinity-purified anti-Spag5 antibodies in immuno electron microscopy shows that in rat elongated spermatids and epididymal sperm the Spag5 protein associates with ODF, but not with the axonemal MTs. This observation is in contrast to that for the other Odf1-binding, MT-binding protein Spag4, which is present between ODF and axoneme. Our data demonstrate that Spag5 has different localization in somatic versus male germ cells suggesting the possibility of different function. Mol. Reprod. Dev. © 2005 Wiley-Liss, Inc. [source] Activity of nitric oxide synthase in mature and immature human spermatozoaANDROLOGIA, Issue 2 2010C. Roessner Summary Nitric oxide (NO) is known to be involved in multiple signal transduction pathways of male germ cells, including sperm capacitation. In somatic cells, NO production was found to be part of apoptosis signalling. The aim of our study was to further clarify the role of NO in spermatozoa by investigation of NO synthase activity with regard to sperm maturity and sperm apoptosis signalling. Semen specimens from 19 healthy donors were subjected to density gradient centrifugation to separate the predominantly mature and immature sperm fraction. NO synthase activity was evaluated using diaminofluoresceine-2-diacetate by FACS. Apoptosis signalling was monitored by flowcytometric analyses of caspase-3 (CP3) and integrity of the transmembrane mitochondrial potential (TMP). TUNEL assay was used to detect DNA fragmentations. Maturity of human spermatozoa was associated with increased NO synthase activity and inactivated apoptosis signalling (lower levels of disrupted TMP, active CP3 and DNA fragmentations, P < 0.05). Activation of apoptosis signalling was significantly negatively correlated to NO production, indicating a rather anti-apoptotic effect of NO. This might underline the recently proposed role of NO in physiological sperm signal transduction, e.g. during capacitation. [source] Mouse testis,brain RNA-binding protein (TB-RBP): expression, purification and crystal X-ray diffractionACTA CRYSTALLOGRAPHICA SECTION D, Issue 11 2001John M. Pascal TB-RBP (testis,brain RNA-binding protein) is a mouse RNA-binding protein that controls the temporal and spatial expression of mRNA. Found most abundantly in brain and male germ cells in the testis, TB-RBP is known to suppress the translation of specific testicular and brain mRNAs as part of cell development. TB-RBP,mRNA complexes can bind microtubules and thereby facilitate RNA translocation. Translin is the human orthologue of TB-RBP which binds to single-stranded ends of DNA sequences in breakpoint regions of chromosomal translocations. TB-RBP/translin has been crystallized in space group P21212. The expression, purification, and crystallization of TB-RBP are described as well as preliminary X-ray diffraction data. The multimeric state of TB-RBP is addressed using dynamic light-scattering results. [source] Origin and evolution of chromosomal sperm proteinsBIOESSAYS, Issue 10 2009José M. Eirín-López Abstract In the eukaryotic cell, DNA compaction is achieved through its interaction with histones, constituting a nucleoprotein complex called chromatin. During metazoan evolution, the different structural and functional constraints imposed on the somatic and germinal cell lines led to a unique process of specialization of the sperm nuclear basic proteins (SNBPs) associated with chromatin in male germ cells. SNBPs encompass a heterogeneous group of proteins which, since their discovery in the nineteenth century, have been studied extensively in different organisms. However, the origin and controversial mechanisms driving the evolution of this group of proteins has only recently started to be understood. Here, we analyze in detail the histone hypothesis for the vertical parallel evolution of SNBPs, involving a "vertical" transition from a histone to a protamine-like and finally protamine types (H,,,PL,,,P), the last one of which is present in the sperm of organisms at the uppermost tips of the phylogenetic tree. In particular, the common ancestry shared by the protamine-like (PL)- and protamine (P)-types with histone H1 is discussed within the context of the diverse structural and functional constraints acting upon these proteins during bilaterian evolution. [source] | |||||||||||||