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At least 55 records · Page 3Linked to original sources
PubMed2006

Tissue-specific RNAi reveals that WT1 expression in nurse cells controls germ cell survival and spermatogenesis.

Using a novel tissue-specific RNA interference (RNAi) approach that mimics the principle by which naturally occurring microRNAs (miRNA) are made, we demonstrate that the Wilms' tumor 1 (WT1) transcription factor has an essential role in spermatogenesis. Mice depleted of WT1 in Sertoli nurse cells suffered from increased germ cell apoptosis, loss of adherens junctions, disregulation of adherence junction-associated genes, and impaired fertility. These effects were recapitulated in transgenic mice expressing a dominant-negative form of WT1 in Sertoli cells, demonstrating the validity of our RNAi approach. Our results indicate that the tumor suppressor WT1 promotes Sertoli cell-germ cell signaling events driving spermatogenesis.

Adherens Junctions↗
PubMed2005

Analysis of hypomorphic KitlSl mutants suggests different requirements for KITL in proliferation and migration of mouse primordial germ cells.

Germ cell development in mice is initiated when a small number of primordial germ cells (PGCs) are set aside from somatic cells during gastrulation. In the subsequent 4 to 5 days, PGCs enter the hindgut, undergo a directed migration away from the hindgut into the developing gonads, and undergo a massive increase in cell number. It is well established that Kit ligand (KITL, also known as stem cell factor and mast cell growth factor) is required for the survival and proliferation of PGCs. However, there is little information on a direct role for KITL in PGC migration. By comparing the effects of multiple Kitl mutations, including two N-ethyl-N-nitrosourea-induced hypomorphic mutations, we were able to distinguish stages of PGC development that are preferentially affected by certain mutations. We provide evidence that the requirements for KITL in proliferation are different in PGCs before and after they start migrating, and different levels of KITL function are required to support PGC proliferation and migration. This study illustrates the usefulness of an allelic series of mutations to dissect developmental processes and suggests that these mutants may be useful for further studies of molecular mechanisms of KITL functions in gametogenesis.

Animals↗
PubMed1984

The development of non-germ cell malignancies within germ cell tumors. A clinicopathologic study of 11 cases.

Eleven male patients had germ cell tumors of the testis (7), mediastinum (3), or retroperitoneum (1) in which non-germ cell malignancies developed. Such malignant non-germ cell elements were present in the primary excisions of five patients and were subsequently found in additional resected tissue in 10 of 11 patients. In the patients who had multiple pathology specimens examined, a progression from atypia to predominant non-germ cell malignancy was often found. The authors believe these malignant elements arose within teratomatous foci, since eight of nine cases had teratoma in the primary tumor, and teratoma was found in subsequently resected tissue in one additional case. Cisplatin therapy frequently "unmasked" the non-germ cell malignant elements by destroying the more chemosensitive germ cell cancers. The prognosis was worst for five patients who developed progressive embryonal rhabdomyosarcoma: two of these patients died of local spread of tumor, whereas a third died of metastatic sarcoma. Only one patient, who had total surgical excision of rhabdomyosarcoma, survived. Other forms of sarcoma that developed within germ cell tumors did not appear to adversely affect the prognosis beyond that of teratoma. It is currently recommended, when feasible, that patients with teratoma and sarcoma undergo total surgical excision. Further treatment with cisplatin regimens, after eradication of the germ cell component, has not been helpful. The role of other forms of chemotherapy remains speculative.

Adolescent↗
PubMed1979

Interrelationships between Sertoli cells and germ cells in the Syrian hamster.

The interrelationships of the Sertoli cells and germ cells in the Syrian hamster were examined using the electron microscope. Demosome-like junctions were observed attaching Sertoli cells to spermatogonia and spermatocytes. In the region of the junctions dense plaques lay on the cytoplasmic surfaces of the plasmalemma of the opposing cells. Sertoli cell cytoplasmic filaments converged in the area of the junctions and inserted into the subsurface densities. Filaments were not observed associated with the subsurface densities of the germ cells. In the region of the junctions a 15...20 nm gap, filled with an attenuate amorphous substance, separated the plasmalemmata. Another attachment device termed "junctional specialization" occurred between Sertoli cells, and preleptotene spermatocytes and all successive developmental steps in the germ cell line in the hamster. The junctional specializations consisted of a mantel of Sertoli cell cytoplasmic filament lying subjacent to the Sertoli cell plasmalemma and an opposed cisterna of the endoplasmic reticulum. In stages VII-VIII preleptotene supermatocytes were observed in transit from the basal compartment to the adluminal compartment. While Sertoli-Sertoli junctions adluminal to the spermatocytes remained intact, typical Sertoli-Sertoli junctions formed between opposed Sertoli cell processes basal to the spermatocytes. It is proposed that, during the passage of spermatocytes in to the adluminal compartment, junctional specializations associated with preleptotene spermatocytes in the basal compartment migrate basal to the spermatocytes and contribute to formation of Sertoli-Sertoli junctions. Treatment of seminiferous tubules with hypertonic media was used to demonstrate that the junctional specializations function in cell-to-cell adhesion. Data indicated that these junctions function to retain the developing spermatids within the seminiferous epithelijm until the time of spermiation. At spermination the junctional specializations disappear and the spermatids drift off into the tubule lumen.

Animals↗
PubMed2004

From stem cells to germ cell tumors and back.

Germ cell tumors originate from ovarian, testicular and extragonadal germ cells. Tumor stem cells can retain most of the features of germ cells and form seminomas or dysgerminomas or, transform into developmentally pluripotent embryonic stem cells and give rise to teratomas or teratocarcinomas. Similar tumors can be experimentally produced in mice from early mouse embryos transplanted to extrauterine sites. The malignant stem cells of teratocarcinomas, called in analogy with their human counterparts embryonal carcinoma (EC), can be isolated and grown in culture and or propagated indefinitely by isotransplantation in syngeneic inbred mice. When injected into the blastocyst, i.e., the embryonic environment from which they have been originally isolated, EC cells lose their malignancy and become benign, participating in the normal development of the injected blastocyst. Injection of EC cells into blastocysts has been used to generate transgenic mice. Developmentally pluripotent non-neoplastic embryonic stem (ES) cells can be produced from mouse blastocysts cultured in vitro. These cells are developmentally similar to EC cells. In contrast to EC cells, ES cells injected into adult mice do not produce teratocarcinomas but only teratomas. Similar ES cells were produced from human blastocysts cultured in vitro. Human ES injected into nude mice produce teratomas composed of various somatic tissues. Human ES cells resemble mouse ES cells, but differ from human EC cells. Like their mouse equivalents, human ES cells could be used for generating experimental models of various diseases and, hopefully, for cell therapy in not so distant future.

Animals↗
PubMed2000

Involvement of Bcl-2 family proteins in germ cell apoptosis during testicular development in the rat and pro-survival effect of stem cell factor on germ cells in vitro.

A large part of germ cells die apoptotically during testicular development in rodents. In the present study, a wave of germ cell apoptosis was observed between days 10 and 30 of postnatal life by in situ 3'-end labeling and DNA fragmentation analysis. To explore the potential involvement of Bcl-2 family members in this process, the expression and localization of some Bcl-2 family proteins (Bcl-2, Bcl-xL, Bcl-w, Bak, Bax, and Bad) and p53 were analyzed during testicular development in the rat by Western blotting and immunohistochemistry. The dynamic changes in the expression profiles of Bcl-2 family proteins are consistent with a model in which germ cells are primed for apoptosis during the first cycle of spermatogenesis by de novo expression of the death effectors Bax and Bad in a p53-dependent manner and these proteins are prevented from triggering further apoptosis after the first spermatogenic cycle has been set up by anti-apoptotic Bcl-2 family proteins Bcl-xL and Bcl-w. To examine whether the pro-survival effect of stem cell factor (SCF) on germ cells in vitro is mediated by Bcl-2 family proteins, the correlation between the pro-survival effect of SCF on germ cells and the expression of the above-mentioned apoptosis-related gene products in the seminiferous tubules at stage XII of the epithelial cycle were also investigated using a tubular culture system. The data suggest that SCF supports germ cell survival during spermatogenesis by up-regulating pro-survival Bcl-2 family proteins, Bcl-w and Bcl-xL, and down-regulating pro-apoptosis Bcl-2 family proteins, e.g. Bax.

Animals↗
PubMed1989

Trout Sertoli cells and germ cells in primary culture: I. Morphological and ultrastructural study.

In order to characterize trout Sertoli cells and germ cells obtained after testis dissociation and cell separation, we have studied their morphology, ultrastructure, survival, and ability to express differentiated activities in primary cultures. After dissociation, the fine structure of Sertoli cells does not differ from that observed in situ and only minor changes are shown for at least 13 days. Until they are flattened in a monolayer, they keep the ability to retain germ cells on their surface. When flattened, some of them are able to divide. At the opposite of meiotic germ cells, spermatogonia can develop independently of Sertoli cells. They are able to proliferate during at least 10 days. Spermatocytes and spermatids are obtained as single cells and multinucleated giant cells (symplasts). In the absence of somatic cells, their maximal viability is approximately 5 days, whereas spermatocytes adhering to Sertoli cells can survive at least 10-12 days, provided trout lipoproteins are present. Spermatocytes are able to differentiate to spermatids, although this process is impaired for some cells. The adhesion of spermatogonia and spermatocytes to Sertoli cells is specific, mediated by desmosome-like junctions and favored by lipoproteins. These data are compared to what is known in mammals and in amphibians.

Animals↗
PubMed2005

Molecular cloning and functional analysis of ESGP, an embryonic stem cell and germ cell specific protein.

Several putative Oct-4 downstream genes from mouse embryonic stem (ES) cells have been identified using the suppression-subtractive hybridization method. In this study, one of the novel genes encoding an ES cell and germ cell specific protein (ESGP) was cloned by rapid amplification of cDNA ends. ESGP contains 801 bp encoding an 84 amino acid small protein and has no significant homology to any known genes. There is a signal peptide at the N-terminal of ESGP protein as predicted by SeqWeb (GCG) (SeqWeb version 2.0.2, http://gcg.biosino.org:8080/). The result of immunofluorescence assay suggested that ESGP might encode a secretory protein. The expression pattern of ESGP is consistent with the expression of Oct-4 during embryonic development. ESGP protein was detected in fertilized oocyte, from 3.5 day postcoital (dpc) blastocyst to 17.5 dpc embryo, and was only detected in testis and ovary tissues in adult. In vitro, ESGP was only expressed in pluripotent cell lines, such as embryonic stem cells, embryonic caoma cells and embryonic germ cells, but not in their differentiated progenies. Despite its specific expression, forced expression of ESGP is not indispensable for the effect of Oct-4 on ES cell self-renewal, and does not affect the differentiation to three germ layers.

Amino Acid Sequence↗
PubMed2004

Differentiation markers of Sertoli cells and germ cells in fetal and early postnatal human testis.

The definition of the temporal sequence of appearance of fetal markers during prenatal and early postnatal development in Sertoli and germ cells may be important for understanding the mechanisms underlying their reexpression in disorders of the adult testis. For this reason, we studied the expression of Sertoli and germ cell markers in 25 human testes spanning a period from 8 gestational weeks to 4 years. Well-characterized antibodies were employed to anti-Müllerian hormone (AMH), cytokeratin 18 (CK18), vimentin (VIM), M2A-antigen (M2A), germ cell alkaline phosphatase (GCAP), and somatic angiotensin-converting enzyme (sACE) on formalin-fixed and microwave-pretreated paraffin sections. In Sertoli cells, AMH and VIM were consistently present. While VIM and CK18 were coexpressed in embryonic testes, CK18 was progressively downregulated and completely absent from the 20th gestational week. M2A was absent or moderately expressed in fetal Sertoli cells but increased during further development. In germ cells, M2A was consistently found in primordial germ cells (PGCs) as well as in M- and T1-prespermatogonia. In contrast, sACE and GCAP were absent from PGCs but were a distinct feature of late M- and early T1-prespermatogonia and appeared predominantly between the 18th and the 22nd gestational weeks. Both T2-prespermatogonia and postnatal prespermatogonia were devoid of any marker. While CK18 represents a differentiation marker for fetal Sertoli cells, M2A, GCAP, and sACE can be used as differentiation markers for the discrimination of different germ cell types during human prespermatogenesis. Because various immunophenotypes reflect distinct differentiation stages, this knowledge may be important for understanding adult testicular pathology.

Aging↗
PubMed2004

Identification of a novel gene, DZIP (DAZ-interacting protein), that encodes a protein that interacts with DAZ (deleted in azoospermia) and is expressed in embryonic stem cells and germ cells.

Evidence from diverse organisms, including humans, suggests that the DAZ (Deleted in Azoospermia) gene and a closely related homolog, DAZL (DAZ-like), are required early in germ cell development to maintain initial germ cell populations. Here we report the identification and characterization of the DZIP (DAZ-Interacting Protein) gene, which encodes at least three different protein isoforms that contain a C2H2 zinc-finger domain. The DZIP gene is expressed predominantly in human embryonic stem cells and fetal and adult germ cells; moreover, two DZIP protein isoforms colocalize with DAZ and/or DAZL proteins in these tissues. Finally, we provide evidence indicating that DZIP may associate with DAZ and its other cofactors in an RNA-binding protein complex that functions in both ES cells and germ cells.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Pluripotent stem cells from germ cells.

To date, stem cells have been derived from three sources of germ cells. These include embryonic germ cells (EGCs), embryonal carcinoma cells (ECCs), and multipotent germ line stem cells (GSCs). EGCs are derived from primordial germ cells that arise in the late embryonic and early fetal period of development. ECCs are derived from adult testicular tumors whereas GSCs have been derived by culturing spermatogonial stem cells from mouse neonates and adults. For each of these lines, their pluripotency has been demonstrated by their ability to differentiate into cell types derived from the three germ layers in vitro and in vivo and in chimeric animals, including germ line transmission. These germ line-derived stem cells have been generated from many species including human, mice, porcine, and chicken albeit with only slight modifications. This chapter describes general considerations regarding critical aspects of their derivation compared with their counterpart, embryonic stem cells (ESCs). Detailed protocols for EGC derivation and maintenance from human and mouse primordial germ cells (PGCs) will be presented.

Adult Stem Cells↗
PubMed2005

Human primordial germ cells and embryonic germ cells, and their use in cell therapy.

Human embryonic germ (hEG) cells derive from the transformation of primordial germ cells (PGCs) under appropriate culture conditions with embryonic fibroblast feeder cells. Although the pluripotent and proliferative capacity of hEG cells is thought to be equivalent to that of human embryonic stem (hES) cells, the difficulties of isolating and maintaining hEG cell lines in vitro have restricted their availability for experimental use. Despite this, some of the factors involved in PGC development, their transformation into embryonic germ cells and the differentiation of embryonic germ cells to specific cell phenotypes have been explored. The potential use of hEG cells in cell therapy applications will, however, depend on a more thorough understanding of how to derive and maintain these cells in vitro.

Animals↗
PubMed1980

Surface interaction in vitro between Sertoli cells and germ cells at different stages of spermatogenesis.

The presence of surface-recognition mechanisms between somatic and germ cells of the seminiferous epithelium has been studied in the rat by an assay in vitro based on the ability of homogeneous populations of spermatogenic cells, at specific differentiative stages, to adhere to monolayers of cultured Sertoli cells. The results show that germ cells adhere specifically to Sertoli cells and that the adhesion is dependent on the differentiative stage of the germ cells. Pachytene spermatocytes show the highest ability to adhere and form typical junctional specializations with the underlying Sertoli cells, while round spermatids adhere much less to the substrate. The possible regulative role of a somatic cell-germ interaction is discussed.

Animals↗
PubMed1989

Temporal appearance of seasonal changes in numbers of Sertoli cells, Leydig cells, and germ cells in stallions.

The temporal appearance of seasonal changes in numbers of Leydig, Sertoli, and germ cells was evaluated to determine if seasonally increased daily spermatozoan production might be preceded by changes in numbers of either of two somatic testicular cells. A significant increase in numbers of spermatogonia and Sertoli cells preceded the significant increase in number of Leydig cells in the approaching breeding season. Seasonal changes in parenchymal weight and in numbers of Sertoli cells, Leydig cells, and germ cells were maximal in May and June. Numbers of A or B spermatogonia in June were 2.4 to 2.5 times the number present in January. During the same time period, numbers of other germ cells, as well as Leydig cells and Sertoli cells, were increased by 1.5 to 1.9 times. The magnitude of change between January and March (first time period that the change was significant) was greater for A spermatogonia (1.7-fold) than for other cell types (1.3-fold to 1.5-fold). Hence, the need to accommodate more spermatogonial progeny might cause increased testicular size and number of somatic cells, including Sertoli cells. Season did not influence the rate of degeneration between A and B spermatogonia. However, in the breeding season, the conversion of B spermatogonia to primary spermatocytes was reduced. The lack of a seasonal difference in the ratio of primary spermatocytes per Sertoli cell was consistent with a limited capacity of individual Sertoli cells to accommodate primary spermatocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

A novel serine/threonine kinase gene, Gek1, is expressed in meiotic testicular germ cells and primordial germ cells.

We have isolated a novel serine/ threonine kinase gene designated Gek1 from mouse primordial germ cell-derived embryonic germ cell. Gek1 is preferentially expressed in meiotic testicular germ cells and primordial germ cells. Gek1 mRNA is also detected in several other tissues, including hematopoietic organs in adult mice and central nervous system in embryos. The Gek1 cDNA encodes a protein with the consensus sequence of the catalytic domain of protein kinases in its N-terminal region. The deduced amino acid sequence of Gek1 in the kinase domain is related to those encoded by the Saccharomyces cerevisiae STE20, CDC15, and Drosophila melanogaster ninaC. The patterns of expression and the structural features of Gek1 suggest that the gene product is involved in signal transduction or nuclear division of germ cells and other proliferating cells. We also show that Gek1 locates on chromosome 11, near the wr locus, showing neuronal and reproductive defects.

Amino Acid Sequence↗
PubMed1987

Ethylnitrosourea treatment increases lectin binding to mouse germ cells.

Germ cell toxicity was assessed by investigating the binding of FITC-labeled lectins to mouse testis cells before and 18 days after treatment with ethylnitrosourea (ENU). Flow cytometry of testis cells dual-labeled with FITC-lectin plus the DNA stain, propidium iodide, allowed analysis of haploid (1C), diploid (2C), and dividing (4C) cell populations. Soybean agglutinin, wheat germ agglutinin, concanavalin A and Limax flavus agglutinin bound to normal mouse testis cells containing 1C, 2C or 4C DNA. Asparagus pea lectin and Bandeireae simplicifolia I isolectin B4 did not. ENU treatment reduced the number of testis cells and increased lectin binding, particularly of those lectins which bound to untreated cells.

Animals↗
PubMed2004

Outcome of patients with residual germ cell or non-germ cell malignancy after resection of primary mediastinal nonseminomatous germ cell cancer.

PURPOSE: To identify prognostic variables and outcomes in patients with primary mediastinal nonseminomatous germ cell tumor (PMNSGCT) with postchemotherapy resection of persistent cancer. PATIENTS AND METHODS: Forty-seven consecutive patients with residual cancer after resection of PMNSGCT were retrospectively reviewed. Univariate comparisons were performed. RESULTS: At diagnosis, 43 patients had elevated serum tumor markers (STMs), and 20 had extramediastinal disease. At resection, 21 patients had elevated STMs. After resection, 26 patients had germ cell tumors (GCT), 12 had malignant transformation of teratoma with elements of non-GCT, and nine had both GCT and non-GCT. Sixteen of 47 patients continuously have no evidence of disease (NED). This includes eight of 26 patients with GCT histology and two of 12 patients with non-GCT histology. Of 27 patients with mediastinal-only disease at presentation, 14 have continuously NED. Of 20 patients with extramediastinal disease at presentation, two have continuously NED. Seven of 21 patients with elevated STMs at time of resection have continuously NED. Sixteen patients received adjuvant chemotherapy, and seven have continuously NED. Overall, 16 of 47 patients have continuously NED, an additional four patients have NED with further therapy (currently NED), two patients are alive with disease, 23 patients died of disease, and two patients died postoperatively. CONCLUSION: The presence of elevated STMs at resection does not appear to alter outcome if residual disease is completely resected. In this poor-risk patient population, surgical resection of persistent cancer, even in the presence of elevated STMs, can still achieve long-term survival.

Adolescent↗
PubMed1990

Effective salvage chemotherapy with etoposide, dactinomycin, and methotrexate in refractory germ cell cancer. Australasian Germ Cell Trial Group.

Fifty-one patients with advanced germ cell malignancy who had either failed to achieve complete remission with initial cisplatin, vinblastine, and bleomycin chemotherapy or who had relapsed after complete response (CR) to this therapy and then proven refractory on retreatment, were treated with etoposide (75 mg/m2 for 3 days), dactinomycin (1 mg/m2 day 1), and methotrexate (30 mg/m2 day 1) (EAM) every 3 weeks. Courses were continued until maximum response without empirical limit, and if complete remission was achieved, two courses of consolidation therapy were given before cessation of treatment. Thirteen patients (25%) were complete responders with residual masses containing fibrosis or benign teratoma being subsequently resected in seven patients. Two patients had persisting viable carcinoma within residual masses that were completely resected, leaving no evidence of disease (NED); the combined CR plus NED rate was 29%. The only pretreatment factor significantly influencing this response rate was tumor volume. Toxicities were moderate, with leukopenia being observed in 28% of patients, but it was severe in only 2%. There was one death from septicemia. Severe nausea and vomiting occurred in only 9% of patients and treatment-related stomatitis was observed in 42%. All patients achieving CR plus NED have been followed for a minimum of 5 years and no relapses have occurred, suggesting that these patients are cured. Unlike other regimens of salvage chemotherapy, this treatment program did not contain cisplatin and it is contended that a completely noncrossresistant drug regimen based on etoposide provides the opportunity to further improve the curability of patients with advanced germ cell cancer.

Antineoplastic Combined Chemotherapy Protocols↗