Characterization of the stem cell niche components within the seminiferous tubules in testicular biopsies of Klinefelter patients

OBJECTIVE

To characterize the tubular environment in testicular biopsy tissues from patients with Klinefelter syndrome (KS).

DESIGN

Observational immunohistochemical study.

SETTING

Academic research unit.

PATIENT(S)

Males with KS and controls at different developmental time points: fetal, prepubertal, peripubertal, and adult.

INTERVENTION(S)

Immunohistochemical analysis of testicular biopsies samples to characterize maturation of Sertoli cells and tubular wall components-peritubular myoid cells (PTMC) and extracellular matrix (ECM) proteins.

MAIN OUTCOME MEASURE(S)

Intensity of antimüllerian hormone staining; proportion of Sertoli cells expressing androgen receptor (AR); and expression of tubular wall markers as characterized by identifying abnormal staining patterns.

RESULT(S)

Decreased expression for alpha smooth muscle actin 2 (ACTA2) was observed in peripubertal and adult KS as well as in Sertoli cell only (SCO) patients. Altered expression patterns for all ECM proteins were observed in SCO and KS biopsy tissues compared with controls. Only for collagen I and IV were altered expression patterns observed between KS and SCO patients. In peripubertal samples, no statistically significant differences were observed in the maturation markers, but altered ECM patterns were already present in some samples.

CONCLUSION(S)

The role of loss of ACTA2 expression in PTMC in the disintegration of tubules in KS patients should be further investigated. Future research is necessary to identify the causes of testicular fibrosis in KS patients. If the mechanism behind this fibrotic process could be identified, this process might be altered toward increasing the chances of fertility in KS patients.

The role of Pten/Akt signaling pathway involved in BPA-induced apoptosis of rat Sertoli cells

Bisphenol-A (BPA), one of endocrine-disrupting chemicals, is a male reproductive toxicant. Previous studies have revealed the direct cytotoxicity of BPA in many cultured cells, such as mitotic aneuploidy in embryonic cells and somatic cells, and apoptosis in neurons and testicular Sertoli cells. To understand the action of BPA and assess its risk, the Pten/Akt pathway was investigated in cultured Sertoli cells to elucidate the mechanism of the reproductive effects of BPA. The results showed that over 50 μM BPA treatment could decrease the viability of Sertoli cells and cause more apoptosis. In addition, BPA could induce the increase in mRNA levels of Pten and Akt. The protein level of Pten was increased; however, the protein levels of phospho-Akt and procaspase-3 were decreased after BPA exposure. Taken together, observed results suggested that the Pten/Akt pathway might be involved in the apoptotic effects of BPA on Sertoli cells.

Presence, localization, and origin of clusterin in normal human spermatozoa

PURPOSE

Clusterin in mammalian semen is a secretory form of clusterin (sCLU) with the heterodimeric structure. It is secreted by the epididymis and seminal vesicle. It is generally agreed that clusterin mainly exists on the surface of abnormal spermatozoa and is implicated in decreased sperm motility, sperm aggregation and infertility. However, few studies observe clusterin in normal spermatozoa, which is presumed to be a novel form. Up to now, the systematical information about the presence, localization, origin and function of clusterin in normal human spermatozoa has yet not been established. The aim of our current study is to systematically research clusterin in normal human spermatozoa.

METHODS

We detected the presence of clusterin via western blot, explored the localization of clusterin using immunofluorescence, and investigated the origin and distribution of clusterin in human testis by western blot and immunohistochemistry.

RESULTS

We found native clusterin in the inner plasma membrane of normal human spermatozoa. It was derived from the testis and showed similar molecular weight and heterodimeric structure compared with sCLU in semen and on the surface of abnormal spermatozoa.

CONCLUSION

Clusterin in normal spermatozoa should be self-synthesized during the later stage of spermatogenesis. The different localization and origin suggested that the clusterin observed by us may be a novel form compared with conventional sCLU on the surface of abnormal spermatozoa.

Expression of P-450 aromatase, estrogen receptor α and β, and α-inhibin in the fetal baboon testis after estrogen suppression during the second half of gestation

Expression of the molecules that modulate the synthesis and action of estrogen in, or reflect function of, Sertoli cells was determined in the fetal testis of baboons in which estrogen levels were suppressed in the second half of gestation to determine whether this may account for the previously reported alteration in fetal testis germ cell development. P-450 aromatase, estrogen receptor (ER) β, and α-inhibin protein assessed by immunocytochemistry was abundantly expressed in Sertoli cells of the fetal baboon testis, but unaltered in baboons in which estrogen levels were suppressed by letrozole administration. Moreover, P-450 aromatase and ERα and β mRNA levels, assessed by real-time RT-PCR, were similar in germ/Sertoli cells and interstitial cells isolated from the fetal testis of untreated and letrozole-treated baboons. These results indicate that expression of the proteins that modulate the formation and action of estrogen in, and function of, Sertoli cells is not responsible for the changes in germ cell development in the fetal testis of estrogen-deprived baboons.

Aberrant distribution of junctional complex components in retinoic acid receptor alpha-deficient mice

Retinoic acid receptor alpha (RARalpha)-deficient mice are sterile, with abnormalities in the progression of spermatogenesis and spermiogenesis. In this study, we investigated whether defective retinoid signaling involved at least in part, disrupted cell-cell interactions. Hypertonic fixation approaches revealed defects in the integrity of the Sertoli-cell barrier in the tubules of RARalpha-deficient testes. Dye transfer experiments further revealed that coupling between cells from the basal to adluminal compartments was aberrant. There were also differences in the expression of several known retinoic acid (RA)-responsive genes encoding structural components of tight junctions and gap junctions. Immunostaining demonstrated a delay in the incorporation of zonula occludens (ZO-1), a peripheral component protein of tight junctions, into the Sertoli cell tight junctions. Markedly reduced expression of connexin-40 in mutant pachytene spermatocytes and round spermatids was found by in situ hybridization. An ectopic distribution of vimentin and disrupted cyclic expression of vimentin, which is usually tightly regulated during spermiogenesis, was found in RARalpha-deficient testes at all ages examined. Thus, the specific defects in spermiogenesis in RARalpha-deficient testes may correlate with a disrupted cyclic expression of RA-responsive structural components, including vimentin, a downregulation of connexin-40 in spermatogenic cells, and delayed assembly of ZO-1 into Sertoli cell tight junctions. Interestingly, bioinformatic analysis revealed that many genes that are components of tight junctions and gap junctions contained potential retinoic acid response element binding sites.

SUMO proteins are involved in the stress response during spermatogenesis and are localized to DNA double-strand breaks in germ cells

Small ubiquitin-like modifiers (SUMO) proteins have been implicated in cellular stress response in different tissues, but whether sumoylation has a similar role during spermatogenesis is currently unknown. In this study, changes in the levels of both free SUMO isoforms and high-molecular weight (HMW) SUMO conjugates were monitored before and after the induction of different types of cellular stresses. Using cell lines and primary cells freshly isolated from mouse testes, significant changes were detected in the levels of SUMO1 and SUMO2/3 conjugates following short exposure of the cells to heat stress and oxidative stress. While high concentrations of H(2)O(2) caused an increase in protein sumoylation, low concentrations of H(2)O(2) mostly caused protein desumoylation. Immunofluorescence studies localized SUMO to the sites of DNA double-strand breaks in stressed germ cells and during meiotic recombination. To study the effect of oxidative stress in vivo, animals exposed to tobacco smoke for 12 weeks were used. Changes in sumoylation of HMW proteins were consistent with their oxidative damage in the tobacco-exposed mice. Our results are consistent with the important roles of different SUMO isoforms in stress responses in germ cells. Furthermore, this study identified topoisomerase 2 alpha as one of the targets of sumoylation during normal spermatogenesis and under stress.

Cynomorium songaricum induces spermatogenesis with glial cell-derived neurotrophic factor (GDNF) enhancement in rat testes

AIM OF THE STUDY

Cynomorium songaricum Ruprecht has been used in traditional Korean medicine to treat male infertility, including sexual dysfunction, by improving kidney function. Glial cell-derived neurotrophic factor (GDNF) produced by Sertoli cells induces the proliferation of undifferentiated spermatogonia. We investigated the effects of Cynomorium songaricum on sperm parameters and GDNF expression in rat testes.

MATERIALS AND METHODS

Sperm analysis, RT-PCR, and Western blotting assays were performed after administration of CS to 8-week-old male Wistar rats for 56 consecutive days (1.0g/kg/day, p.o.), the period of sperm formation in the rat.

RESULTS AND CONCLUSIONS

The CS-treated animals showed significant increases in epididymal sperm count and absolute testes weights compared to the control group. CS also increased the expression of GDNF at both the mRNA and protein levels. These results suggest that CS may improve male fertility by enhancing spermatogenesis and GDNF expression.

Alterations of Sertoli cell activity in the long-term testicular germ cell death process induced by fetal androgen disruption

Fetal androgen disruption, induced by the administration of anti-androgen flutamide (0.4, 2, and 10 mg/kg day) causes a long-term apoptosis in testicular germ cells in adult male rat offspring. One of the questions raised by this observation is the role of the Sertoli cells in the adult germ cell apoptotic process. It is shown here that Sertoli cells originating from 15-day-old rats treated in utero with the anti-androgen (10 mg/kg d) did no longer protect adult germ cells against apoptosis. Indeed, untreated spermatocytes or spermatids exhibited increased (P<0.0001) active caspase-3 levels when co-cultured with Sertoli cells isolated from rat testes exposed in utero to the anti-androgen. This alteration of Sertoli cell functions was not due to modifications in the androgen signal in the adult (90-day-old) animals, since plasma testosterone and estradiol, androgen receptor expression, and androgen-targeted cell number (e.g., Sertoli cells in the seminiferous tubules) were not affected by the fetal androgen disruption. In contrast, this inability of Sertoli cells to protect germ cells against apoptosis could be accounted for by the potential failure of Sertoli cell functions. Indeed, adult testes exposed in utero to anti-androgens displayed decreased levels of several genes mainly expressed in adult Sertoli cells (anti-Mullerian hormone receptor type II (AMHR2), Cox-1, cyclin D2, cathepsin L, and GSTalpha). In conclusion, fetal androgen disruption may induce alterations of Sertoli cell activity probably related to Sertoli cell maturation, which potentially leads to increased adult germ cell apoptosis.

Ontogeny of androgen and estrogen receptor expression in porcine testis: Effect of reducing testicular estrogen synthesis

Reducing endogenous estrogen leads to increased proliferation of porcine Sertoli cells during the first 2 months of life. The resulting increase in porcine Sertoli cell numbers is maintained through puberty. The reduced estrogen appears to be the direct hormonal mediator because essentially no changes are observed in other hormones. However, the mechanism for this effect on Sertoli cell proliferation is unknown. The objective of these studies was to evaluate estrogen receptors alpha and beta (ESR1 and ESR2) in conjunction with androgen receptor (AR) on Sertoli cells and other testicular cell types, as an initial step toward understanding how reduced estrogen leads to increased Sertoli cell numbers. Testis sections from treated animals (aromatase inhibition to decrease endogenous estrogen beginning at 1 week of age) and from littermate controls treated with vehicle were subjected to immunocytochemical labeling for ESR1, ESR2, and AR. Three observers scored Sertoli cells, interstitial cells, peritubular myoid cells, and germ cells for intensity of labeling (0: absent; 1+: weak; 2+: moderate; or 3+: strong labeling). AR in Sertoli cells was readily detected at 1 week of age, was very faint in 2-month vehicle controls, and labeling appeared to increase in 3-month vehicle controls. AR in Sertoli cells, interstitial cells, and apparently germ cells was increased in treated animals at 2 months of age compared with the vehicle controls. This increase was confirmed in western blots. ESR1 and ESR 2 were clearly present in Sertoli cells from 1-week-old animals; ESR in Sertoli cells generally decreased with age with the decrease more apparent for ESR2. ESR1 in Sertoli cells and peritubular myoid cells exhibited some treatment-related effects but reduction of endogenous estrogen did not appear to affect ESR2 in the boar testis. The observed alterations in AR and ESR1 may mediate the increases in Sertoli cell proliferation following inhibition of endogenous estrogen production or may reflect the altered function of the Sertoli cells and peritubular myoid cells.

Changes in Vinexin Expression Patterns in the Mouse Testis Induced by Developmental Exposure to 17Beta-Estradiol1

In the seminiferous epithelium, numerous cell interactions between Sertoli cells and Sertoli-germ cells are established by specialized proteins so as to maintain the functionality of the testis. Exogenous estrogen exposure can result in alterations to these interactions and cause pathologies, including impaired spermatogenesis and tumorigenesis. In the present study, with the aim of finding markers of the action of estrogenic compounds in the mammalian testis, we focused on investigating molecules that are linked to cellular junctions. We found that the testicular vinexin (sorbin and SH3 domain-containing protein 3, encoded by the Sorbs3 gene) pattern underwent significant changes after developmental exposure to 17beta-estradiol (E(2)). Vinexin is an adaptor protein that is implicated in cell adhesion and actin-cytoskeletal reorganization. We characterized, at the protein and mRNA levels, the expression patterns of vinexin isoforms during testis development and in defined cell types from the seminiferous tubule. The protein expression patterns of vinexin-interacting proteins flotillin 1 and vinculin were also analyzed. Thus, we have identified a novel association between a vinexin isoform and germ cells, which contrasts with the predominant localization of the gamma isoform in Sertoli cells. The effects of E(2) on the testes of developmentally exposed mice were evident, with total depletion of the germ-cell-associated vinexin isoform and a noticeable decrease in Sertoli-cell-related vinexin gamma.

A re-evaluation of gelsolin at ectoplasmic specializations in sertoli cells: the influence of serum in blocking buffers on staining patterns

In this study, we test the hypothesis that gelsolin immunolocalized in actin filament-rich ectoplasmic specializations may be exogenous gelsolin present in normal serum used in blocking buffers, and that binds to the intercellular adhesion plaques during tissue processing. Fixed frozen sections of rat and rabbit testis were pre-treated with standard blocking buffers containing 5% normal goat serum (NGS) and then incubated with anti-gelsolin antibodies in the presence of 1% NGS. Other sections were treated in a similar fashion, but in buffers not containing NGS. Sections were then labeled with secondary antibody conjugated to a fluorochrome. Localized staining at ectoplasmic specializations occurred only in sections treated with NGS. The only positive staining in sections not treated with NGS was associated with seminiferous tubule walls and blood vessels in rabbit tissue. The antibodies reacted with a single band at the appropriate molecular weight for gelsolin on immunoblots of NGS, but did not react on immunoblots of testis or seminiferous epithelium. We conclude that gelsolin localized at ectoplasmic specializations using current commercially available antibodies is a result of non-specific binding to the fixed tissues of gelsolin present in blocking buffers.

Claudin-11 expression and localisation is regulated by androgens in rat Sertoli cells in vitro

Claudin-11 and occludin are protein components in tight junctions (TJs) between Sertoli cells which are important for the maintenance of the blood-testis barrier. Barrier formation occurs during puberty, with evidence suggesting hormonal regulation of both claudin-11 and occludin. This study aimed to investigate the regulation of claudin-11 and occludin mRNA expression by testosterone (T) and FSH and their immunolocalisation at rat Sertoli cell TJs in vitro, and to correlate any steroid regulation with the functional capacity of TJs. Sertoli cells formed functional TJs within 3 days as assessed by transepithelial electrical resistance (TER). Both T and dihydrotestosterone significantly (P < 0.01) increased TER twofold and claudin-11 mRNA two- to threefold within 3 days. FSH partially stimulated TER and claudin-11 mRNA, but estradiol had no effect. T also promoted claudin-11 localisation into extensive intercellular contacts. In contrast to claudin-11, Tand FSH did not change occludin mRNA expression, however, T promoted localisation of occludin at cell contacts in a similar manner to claudin-11. Addition of flutamide to T-stimulated cells caused a twofold decrease in both TER and claudin-11 mRNA expression, and resulted in the loss of both proteins from cell contacts. This effect was reversible following flutamide removal. It is concluded that androgens i) co-regulate claudin-11 mRNA expression and TER, implicating claudin-11 in TJ formation and ii) promote the localisation of claudin-11 and occludin at Sertoli cell contacts. Hence, the ability of androgens to maintain spermatogenesis in vivo is partly via their effects on TJ proteins and regulation of the blood-testis barrier.

Phosphoprotein enriched in astrocytes-15 is expressed in mouse testis and protects spermatocytes from apoptosis

Phosphoprotein enriched in astrocytes (PEA-15) is a 15 kDa acidic serine-phosphorylated protein expressed in different cell types, especially in the CN. We initially detected the expression of PEA-15 in primary cultures of Sertoli cells. To assess the presence and localization of PEA-15 in the mouse testis, we studied the expression pattern of the PEA-15 protein by immunohistochemistry and mRNA byin situhybridization. Both the protein and the mRNA of PEA-15 were localized in the cytoplasm of Sertoli cells, all types of spermatogonia, and spermatocytes up till zygotene phase of the meiotic prophase. Subsequently, with ongoing development of the spermatocytes, the expression decreased and was very low in the cytoplasm of diplotene spermatocytes. To analyze the possible role of PEA-15 in the developing testis, null mutants for PEA-15 were examined. As the PEA-15 C terminus contains residues for ERK binding, we studied possible differences between the localization of the ERK2 protein in wild type (WT) andPEA-15−/−mice. In the WT testis, ERK2 was localized in the cytoplasm of Sertoli cells, B spermatogonia, preleptotene, leptotene, and zygotene spermatocytes, whereas in the KO testis, ERK2 was primarily localized in the nuclei of these cells and only little staining remained in the cytoplasm. Moreover, in PEA-15-deficient mice, significantly increased numbers of apoptotic spermatocytes were found, indicating an anti-apoptotic role of PEA-15 during the meiotic prophase. The increased numbers of apoptotic spermatocytes were not found at a specific step in the meiotic prophase.

Expression of hedgehog signalling components in adult mouse testis

Hedgehog (Hh) signalling is known to regulate many aspects of normal development as well as being upregulated in various cancers. Signalling is mediated by the Gli family of zinc finger transcription factors. Based on observations that deletion of one of the three Hh genes, Dhh, leads to male infertility, we hypothesized that regulated expression of Hh signalling components would be a feature of adult spermatogenesis. We used in situ hybridization to characterise Gli gene expression in juvenile and adult mouse testes. In the first wave of spermatogenesis, mRNAs encoding all three Glis are detected in spermatogonia and Sertoli cells. In adult mouse testes, these transcripts are observed in spermatogonia and spermatocytes, with reduced signal intensity in round spermatids. The mRNAs encoding key effectors of Hh signalling, Ptc2, Smo, and Fu, are also most apparent in spermatogonia, spermatocytes, and to a lower extent in round spermatids. In contrast, mRNA encoding SuFu, a negative regulator of Hh signalling, was most predominant in round spermatids and the protein is evident in round and elongating spermatids, suggesting that SuFu protein may switch off Hh signalling in haploid germ cells. Overall, the coordinated expression pattern of these genes in adult mouse testis indicates a role for Hh signalling in spermatogenesis.

Cellular localization of sphingomyelin synthase 2 in the seminiferous epithelium of adult rat testes

Sphingomyelin synthase 2 (SMS2) is an enzyme that catalyzes the conversion of phosphatidylcholine and ceramide to sphingomyelin and diacylglycerol, and it is crucial to cellular lipid metabolism. Using the technique of subtraction hybridization, we have isolated a full-length cDNA encoding SMS2 from rat testes, which shared 93 and 87% identity at the nucleotide level with SMS2 in mice and humans respectively. A specific polyclonal antibody was prepared against a 20 amino acid peptide of NH(2)-FSWPLSWPPGCFKSSCKKYS-COOH near the C-terminus of SMS2. Studies by RT-PCR and immunoblotting have shown that the expression of SMS2 was limited to late round spermatids and elongating spermatids, but it was not detected in late elongate spermatids and Sertoli cells. Furthermore, SMS2 was shown to associate with the developing acrosome beginning in late round spermatid through elongating spermatids (but not late elongate spermatids) and the cell membrane in studies using fluorescent microscopy and immunohistochemistry. These data were further confirmed by studies using immunogold electron microscopy. The expression of SMS2 in the seminiferous epithelium is stage-specific with its highest expression detected in the acrosome region in late round spermatids from stages VIII-IX, and also in the acrosome in elongating spermatids with diminished intensity in stages X-V; however, it was not found in the acrosome in elongate spermatids in stages VI-VIII. Collectively, these results suggest that SMS2 may play a crucial role in the lipid metabolism in acrosome formation and the plasma membrane restructuring from late round spermatids to early elongating spermatids.

Primary testicular lesions are associated with testicular germ cell tumors of adult men

The present study aims to establish the nature and frequency of testicular lesions in the parenchyma adjacent to testicular germ cell tumors (TGCT) to improve understanding of the factors involved in the development of testicular cancer. Fifty-three cases of TGCT that were fixed in both neutral-buffered formalin and Bouin solution, allowing for the nuclear characterization of Sertoli cells (SCs), were included in this study. In each case, at least 3 sections of different areas of preserved parenchyma surrounding the TGCT were studied. We found Leydig cell hyperplasia, microlithiasis, angiopathy, adenomatous hyperplasia of the rete testis, SC nodules, SC dysgenesis and involution, SC-only tubules, tubular atrophy, adluminal compartment lesions, hypospermatogenesis associated with spermatocyte sloughing, spermatogonial maturation arrest, and hypertrophic and multinucleated spermatogonia. These lesions were found in regions both adjacent and far away from the tumoral mass, and abnormal seminiferous tubules were found intermingled with those showing complete spermatogenesis, suggesting that these lesions are primary and existed before the development of the tumor. Our study suggests that SCs might play a more important role in the development of testicular tumors than previously thought. Our data supports the hypothesis that there is an abnormal differentiation of SCs, caused either by genetic anomalies or by environmental agents during fetal life. This abnormal SC differentiation may cause not only primary spermatogenesis failure and spermatogenesis arrest at different levels, but may also contribute to the poor differentiation of gonocytes into spermatogonia. The abnormal gonocyte differentiation might favor the development of dysplastic germ cells that may later transform into intratubular germ cell neoplasia, unclassified type.

The proximal Gata4 promoter directs reporter gene expression to sertoli cells during mouse gonadal development

The GATA4 transcription factor is an important developmental determinant for many organs, such as the heart, gut, and testis. Despite this pivotal role, our understanding of the transcriptional mechanisms that control the proper spatiotemporal expression of the GATA4 gene remains limited. We have generated transgenic mice expressing a green fluorescent protein (GFP) marker under the control of rat Gata4 5' flanking sequences. Several GATA4-expressing organs displayed GFP fluorescence, including the heart, intestine, and pancreas. In the gonads, while GATA4 is expressed in pregranulosa, granulosa, and theca ovarian cells, and Sertoli, Leydig, and peritubular testicular cells, the first 5 kb of Gata4 regulatory sequences immediately upstream of exon 1 were sufficient to direct GFP reporter expression only in testis and, specifically, in Sertoli cells. Onset of GFP expression occurred after Sertoli cell commitment and was maintained in these cells throughout development to adulthood. In vitro studies revealed that the first 118 bp of the Gata4 promoter is sufficient for full basal activity in several GATA4-expressing cell lines. Promoter mutagenesis and DNA-binding experiments identified two GC-box motifs and, particularly, one E-box element within this -118-bp region that are crucial for its activity. Further analysis revealed that members of the USF family of transcription factors, especially USF2, bind to and activate the Gata4 promoter via this critical E-box motif.

A complex containing alpha6beta1-integrin and phosphorylated focal adhesion kinase between Sertoli cells and elongated spermatids during spermatid release from the seminiferous epithelium

Spermiation is the final step of spermatogenesis and culminates in the disengagement (release) of elongated spermatids from Sertoli cells into the seminiferous tubule lumen. Spermiation failure, wherein spermatids are retained by Sertoli cells instead of releasing, occurs after hormone suppression. The mechanisms involved in spermatid disengagement and retention are not well understood. We previously showed that beta(1)-integrin is associated with spermatids until the point of disengagement, but the ectoplasmic specialisation junction (ES) is not. The aims of this paper are to further characterise the complex that is present immediately prior to spermatid disengagement by identifying the alpha-integrin form dimerised with beta(1)-integrin, localising focal adhesion kinase (FAK) and determining if microtubules are involved. Adult Sprague-Dawley rats received testosterone and oestradiol implants and an FSH antibody for 7 days to suppress testicular testosterone and FSH and induce spermiation failure. Control rats were treated with saline. Immunohistochemical analysis showed that alpha(6)-integrin and a phosphorylated form of FAK (FAK-Tyr(397)) are present between late spermatids and Sertoli cells after ES removal, until the point of disengagement, and both proteins remain associated with retained spermatids after spermiation failure induced by hormone suppression. Using dual-label immunofluorescence, tubulins (and thus microtubules) were observed to co-localise with ES, but were neither associated with elongated spermatids just prior to release nor with retained spermatids following hormone suppression. These results suggest that microtubules are not involved in the final release of spermatids from Sertoli cells. We conclude that spermatid release during spermiation is mediated by a 'disengagement complex' containing alpha(6)beta(1)-integrin and phospho-FAK, the function of which can be affected by gonadotrophin suppression.

Expression of galectin-3 in gonads and gonadal sex cord stromal and germ cell tumors

Galectin-3, a beta-galactoside-binding lectin, has been implicated in many human malignancies, but has seldom been studied in human gonads and gonadal tumors. The aim of our study was to investigate galectin-3 mRNA and protein expression in normal ovaries and testes as well as in a variety of 51 gonadal sex cord stromal and germ cell tumors, and two testicular seminomatous and non-seminomatous cell lines, using either real-time PCR or immunohistochemistry. In human testes, galectin-3 is specifically expressed in mature Sertoli cells and Leydig cells, and is absent from fetal and pre-pubertal testes, suggesting a hormone-dependence of this gene. In human ovaries, galectin-3 is absent from granulosa cells, as well as from granulosa cell and Sertoli-Leydig cell tumors, and is not a useful marker in distinguishing granulosa cell from Sertoli-Leydig cell tumors. In testicular tumorigenesis, galectin-3 has a dual function according to the histological type of tumors and their hormone dependency. In malignant testicular Sertoli cell tumors, the expression of galectin-3 is down-regulated while, in benign Leydig cell tumors, this expression is maintained, indicating the possible implication of this gene in the development of more aggressive testicular sex cord stromal tumors. In contrast to sex cord stromal tumors, galectin-3 expression is up-regulated in testicular germ cell tumors. By real-time PCR, we demonstrated a significant elevation of the galectin-3 mRNA level in non-seminomatous testicular germ cell tumors and cell line as compared to normal testes and seminomas (p=0.0432 and p=0.0247, respectively), indicating the possible role of this gene in the non-seminomatous differentiation of germ cell tumors.

Regulated production of activin A and inhibin B throughout the cycle of the seminiferous epithelium in the rat

Production and regulation of activin A and inhibin B during the cycle of the seminiferous epithelium were investigated in adult rats. Immunohistochemistry localised the activin beta(A)-subunit to the Sertoli cell cytoplasm, with much weaker expression in spermatocytes and spermatids. Both activin A and inhibin B, measured by ELISA were secreted by, seminiferous tubule fragments over 72 h in culture. Activin A was secreted in a cyclic manner with peak secretion from tubules isolated at stage VIII. Tubules collected during stage VI produced the least activin A. Inhibin B secretion was highest from stage IX-I tubules and lowest from stage VII tubules. Addition of interleukin-1beta (IL-1beta) had relatively little effect on activin A or inhibin B secretion in culture. In contrast, the peak secretion of activin A by stage VIII tubules was blocked by co-incubation with an excess of human recombinant IL-1 receptor antagonist, whereas inhibin B secretion increased slightly. Dibutyryl cAMP stimulated activin A secretion by late stage VII and VIII tubules and stimulated inhibin B across all stages. These data indicate that activin A and inhibin B are cyclically regulated within the seminiferous epithelium, with endogenous IL-1 (presumably IL-1alpha produced by the Sertoli cells), responsible for a peak of activin A production subsequent to sperm release at stage VIII. These data provide direct evidence that production of activin A and inhibin B by the Sertoli cell is locally modulated by IL-1alpha , in addition to FSH/cAMP, under the influence of the developing spermatogenic cells.

Activating mutations in the luteinizing hormone receptor gene: a human model of non-follicle-stimulating hormone-dependent inhibin production and germ cell maturation

CONTEXT

Familial male-limited precocious puberty is a dominant autosomal genetic disease caused by activating LH receptor gene mutations, clinically expressed only in males. In preliminary studies, in addition to the expected testosterone increase, we found high inhibin B levels before the age of normal puberty.

OBJECTIVES

The objective of the study was to assess the cellular origin of serum inhibin thanks to testis section immunostaining.

MAIN OUTCOME MEASURES

Serum testosterone, gonadotropin, inhibin B, pan-alphaC-inhibin, and anti-Mullerian hormone levels were measured. Immunostaining was performed using specific anti-alpha- and anti-beta-subunit antibodies.

SUBJECTS AND METHODS

Five boys from three families (mutation M398T or I542L) were investigated at onset (2-6 yr), on ketoconazole treatment, and at adolescence. Testis biopsies were performed in three subjects before the disease was fully characterized.

RESULTS

The high testosterone levels were suppressed by ketoconazole. Anti-Mullerian hormone levels were inversely related to testosterone: low at diagnosis, elevated after testosterone suppression. Despite FSH suppression, inhibin B and pan-alphaC-inhibin levels were high from clinical onset to adolescence. Biopsy specimens showed normal Sertoli cell complement and germ cell maturation until the spermatocyte II stage. Sertoli and Leydig cells displayed positive inhibin alpha-subunit immunostaining. Only Leydig cells and spermatogonia stained positively for the inhibin betaB-subunit.

CONCLUSIONS

Familial male-limited precocious puberty is a unique model of inhibin B secretion, demonstrating that Leydig cells can produce significant amounts of the dimeric molecule. Our results also suggest that the pubertal FSH rise is not required for full expression of the two inhibin B genes and for the initiation of germ cell maturation.

Glial cell-line-derived neurotropic factor and its receptors are expressed by germinal and somatic cells of the rat testis

Glial cell-line-derived neurotropic factor (GDNF) and its receptors glial cell-line-derived neurotropic factor alpha (GFR1alpha) and rearranged during transformation (RET) have been localized in the rat testis during postnatal development. The three mRNAs, and GDNF and GFR1alpha proteins were detected in testis extracts from 1- to 90-day-old rats by reverse transcriptase PCR and Western blotting respectively. The three mRNAs were present in Sertoli cells from 20- and 55-day-old rats, pachytene spermatocytes (PS), and round spermatids (RS). The GDNF and GFR1alpha proteins were detected in PS, RS, and Sertoli cells. GDNF and GFR1alpha were also detected using flow cytometry in spermatogonia and preleptotene spermatocytes, and in secondary spermatocytes. The localization of GDNF and GFR1alpha in germ and Sertoli cells was confirmed by immunocytochemistry. The hypothesis that GDNF may control DNA synthesis of Sertoli cells and/or spermatogonia in the immature rat was addressed using cultures of seminiferous tubules from 7- to 8-day-old rats. Addition of GDNF for 48 h resulted in a twofold decrease in the percentage of spermatogonia able to duplicate DNA, whereas Sertoli cells were not affected. These results are consistent with a role of GDNF in inhibiting the S-phase entrance of a large subset of differentiated type A spermatogonia, together with an enhancing effect of the factor on a small population of undifferentiated (stem cells) spermatogonia. Moreover, the wide temporal and spatial expression of GDNF and its receptors in the rat testis suggest that it might act at several stages of spermatogenesis.

Hepatocyte growth factor modulates in vitro survival and proliferation of germ cells during postnatal testis development

The hepatocyte growth factor (HGF) is a pleiotropic cytokine that influences mitogenesis, motility and differentiation of many different cell types by its tyrosine kinase receptor c-Met. We previously demonstrated that the c-Met/HGF system is present and functionally active during postnatal testis development. We found also that spermatozoa express c-Met and that HGF has a positive effect on the maintenance of sperm motility. In the present paper, we extend our study on the germ cells at different stages of differentiation during the postnatal development of the testis. We demonstrate that c-met is present in rat spermatogonia, pachytene spermatocytes and round spermatids and that HGF significantly increases spermatogonial proliferation in 8- to 10-day-old pre-pubertal rats. At this age HGF does not affect Sertoli cells and peritubular myoid cells proliferation. In addition, we studied the effect of the factor on germ cell apoptosis and we show that HGF prevents the germ cell apoptotic process. We also studied the effect of HGF on 18- to 20-day-old and 28- to 30-day-old rat testes. At these ages also the factor significantly increases germ cell duplication and decreases the number of apoptotic cells. However, the effect on programmed cell death is higher in the 8- to 10-day-old rats and declines in the older animals. In conclusion, we report that rat germ cells (spermatogonia, pachytene spermatocytes and round spermatids) express c-met and that HGF modulates germ cell proliferating activity and apoptosis in vitro. These data indicate that the c-Met/HGF system is involved in male germ cell homeostasis and, consequently, has a role in male fertility.

The association between intratubular seminoma and invasive germ cell tumors☆

Intratubular seminoma (ITS) has been defined as the complete filling of the seminiferous tubules with seminoma cells with no Sertoli cells present. This contrasts with intratubular germ cell neoplasia, unclassified (IGCNU), where the malignant germ cells are interspersed by Sertoli cells. We aimed to determine the relationship between these 2 entities and the association between ITS and invasive classic seminomas. We therefore examined the morphology and immunochemistry of ITS and IGCNU adjacent to germ cell tumors to differentiate the patterns, frequency, and distribution of these lesions. We found that ITS was seen in equal frequency adjacent to seminomas as it was to nonseminomas. The presence of ITS in non-seminomatous germ cell tumors suggests that it is a true in situ lesion rather than representative of intratubular spread of an existing seminoma. However, because it is not specifically associated with seminoma, we suggest that it is not useful to discriminate this lesion from IGCNU and that it merely represents an advanced form of IGCNU on the way to invasive malignancy.

Detection of anti-Mullerian hormone receptor II protein in the postnatal rat testis from birth to sexual maturity

Anti-Mullerian hormone (AMH) produced by the immature Sertoli cells negatively regulates the postnatal Leydig cell (i.e. adult Leydig cells/ALC) differentiation, however, the mechanism is sparsely understood. AMH negatively regulates the steroidogenic function of fetal Leydig cells (FLC) and ALC. However, when this function is established in the ALC lineage and whether AMH has a function in FLC in the postnatal testis are not known. Therefore, the objectives of this study were to examine the presence of AMH receptor type II (AMHR-II) in FLC and cells in the ALC lineage in the postnatal mammalian testis using the rat model Male Sprague Dawley rats of days 1, 5, 7-21, 28, 40, 60 and 90 were used. AMHR-II in testicular interstitial cells was detected in testis tissue using immunocytochemistry. Findings showed that the mesenchymal and the progenitor cells of the ALC lineage, were negative for AMHR-II. The newly formed ALC were the first cell type of the ALC lineage to show positive labeling for AMHR-II, and the first detection was on postnatal day 13, although they were present in the testis from day 10. From days 13-28, labeling intensity for AMHR-II in the ALC was much weaker than those at days 40-90. FLC were also positive. The time lag between the first detection of the newly formed ALC in the testis and the first detection of AMHR-II in them suggests that the establishment of the negative regulatory role of AMH on ALC steroidogenesis does not take place immediately upon their differentiation; no change in cell size occurs during this period. The absence of AMHR-II in mesenchymal cells suggests that it is unlikely that the negative regulatory effect of AMH on ALC differentiation in the postnatal testis is achieved via a direct action of AMH on mesenchymal cells. The presence of AMHR-II in postnatal FLC suggests a possible role by AMH on FLC, which warrants future investigations.

McCune-Albright syndrome in a boy may present with a monolateral macroorchidism as an early and isolated clinical manifestation

BACKGROUND

Testis enlargement in McCune-Albright syndrome (MAS) is generally bilateral and associated with clinical and biochemical manifestations of sexual precocity.

CASE REPORT

We describe for the first time an unreported clinical expression of MAS in a 4.6-year-old boy presenting with monolateral testis enlargement and no signs of sexual precocity or other clinical manifestations of MAS at the time of presenting with macroorchidism. Both testosterone and LHRH-stimulated gonadotropin levels were in the prepubertal range. Serum inhibin B was increased to a pubertal level indicating Sertoli cell activation. The histological and immunocytochemical evaluation of the enlarged testis revealed Sertoli cell hyperplasia with no mature Leydig cells. Mutation R201C of GNAS1 gene, classically responsible for MAS, was identified in DNA samples from the right testis biopsy and leukocytes.

CONCLUSIONS

(a) MAS should be taken into consideration in the clinicopathological approach to a boy with monolateral macroorchidism; (b) testicular enlargement may be only the presenting clinical manifestation of MAS and is not necessarily linked to manifestations of peripheral precocious puberty; (c) testicular autonomous hyperfunction in MAS may be restricted to Sertoli cells, as also demonstrated previously by others.

Cellular localization of NGF and its receptors trkA and p75LNGFR in male reproductive organs of the Japanese monkey, Macaca fuscata fuscata

The actions of neurotropins are not restricted to the nervous system. Immunohistochemical methods were used in the present study to clarify distribution of nerve growth factor (NGF) and its receptors TrkA and p75LNGFR in excurrent ducts of the adult male Japanese monkey (Macaca fuscata fuscata). NGF was found in the seminal vesicle, epididymis, and testis, and has been thought to affect male reproductive functions. Leydig cells, Sertoli cells, and spermatogonia at various stages were positively stained for NGF, as well as for TrkA and p75LNGFR. Signals for these proteins were also found in epithelial cells and stromal tissues of the caudal epididymidis, as well as in the seminal vesicle. In the prostate, smooth muscle cells and basal cells were positively stained for NGF, TrkA, and p75 LNGFR. The results were comparatively discussed.

Expression of stress inducible protein 1 (Stip1) in the mouse testis

Phthalate esters are considered endocrine disruptors that interfere with the endocrine balance and development of the mammalian testis. Mono-2-ethylhexyl phthalate (MEHP), the active metabolite of the ubiquitously used plasticizer di-2-ethylhexyl phthalate (DEHP), acts upon Sertoli cells as initial target. By subtractive cDNA libraries we identified genes deregulated as response to MEHP in primary cultures of mouse Sertoli cells. The expression of mouse stress inducible protein 1 (Stip1) was detected as upregulated as a result of MEHP exposure. Stip1 is a cochaperone protein that is homologous to the human heat shock cognate protein 70 (hsc70)/heat shock protein 90 (hsp90)-organizing protein (Hop). To assess the presence and localization of Stip1 in mouse testis and its potential role in stress defense, we studied the expression pattern of the Stip1 protein by immunohistochemistry and of the mRNA by in situ hybridization. Both the protein and the mRNA of Stip1 were mainly found in the cytoplasm of all types of spermatogonia and spermatocytes up till zygotene, the expression decreased during late pachytene and was very weak in diplotene spermatocytes and round spermatids. Interestingly, this expression pattern resembled the pattern of stress sensitivity of spermatogenic cells in that the most sensitive cell types show the weakest expression of Stip1. This suggests an important role for Stip1 in the ability of germ cells to survive in stress conditions including high temperatures.

Histochemical analysis of glycoconjugates in the domestic cat testis

The localization and characterization of oligosaccharide sequences in the cat testis was investigated using 12 lectins in combination with the beta-elimination reaction, N-Glycosidase F and sialidase digestion. Leydig cells expressed O-linked glycans with terminal alphaGalNAc (HPA reactivity) and N-glycans with terminal/internal alphaMan (Con A affinity). The basement membrane showed terminal Neu5Acalpha2,6Gal/GalNAc, Galbeta1,3GalNAc, alpha/betaGalNAc, and GlcNAc (SNA, PNA, HPA, SBA, GSA II reactivity) in O-linked oligosaccharides, terminal Galbeta1,4GlcNAc (RCA120 staining) and alphaMan in N-linked oligosaccharides; in addition, terminal Neu5acalpha2,3Galbeta1,4GlcNac, Forssman pentasaccharide, alphaGal, alphaL-Fuc and internal GlcNAc (MAL II, DBA, GSA I-B4, UEA I, KOH-sialidase-WGA affinity) formed both O- and N-linked oligosaccharides. The Sertoli cells cytoplasm contained terminal Neu5Ac-Galbeta1,4GlcNAc, Neu5Ac-betaGalNAc as well as internal GlcNAc in O-linked glycans, alphaMan in N-linked glycoproteins and terminal Neu5Acalpha2,6Gal/ GalNAc in both O- and N-linked oligosaccharides. Spermatogonia exhibited cytoplasmic N-linked glycoproteins with alphaMan residues. The spermatocytes cytoplasm expressed terminal Neu5Acalpha2,3Galbeta1,4 GlcNAc and Galbeta1,3GalNAc in O-linked oligosaccharides, terminal Galbeta1,4GlcNAc and alpha/betaGalNAc in N-linked glycoconjugates. The Golgi region showed terminal Neu5Acalpha2,3Galbeta1,4GlcNac, Galbeta1,4GlcNAc, Forssman pentasaccharide, and alphaGalNAc in O-linked oligosaccharides, alphaMan and terminal betaGal in N-linked oligosaccharides. The acrosomes of Golgi-phase spermatids expressed terminal Galbeta1,3GalNAc, Galbeta1,4GlcNAc, Forssmann pentasaccharide, alpha/betaGalNAc, alphaGal and internal GlcNAc in O-linked oligosaccharides, terminal alpha/betaGalNAc, alphaGal and terminal/internal alphaMan in N-linked glycoproteins. The acrosomes of cap-phase spermatids lacked internal Forssman pentasaccharide and alphaGal, while having increased alpha/betaGalNAc. The acrosomes of elongated spermatids did not show terminal Galbeta1,3GalNAc, displayed terminal Galbeta1,4GlcNAc and alpha/betaGalNAc in N-glycans and Neu5Ac-Galbeta1,3GalNAc in O-linked oligosaccharides.

Quantification of stem cell factor mRNA levels in the rat testis: usefulness of clusterin mRNA as a marker of the amount of mRNA of Sertoli cell origin in post pubertal rats

Spermatogenesis is a complex cellular process regulated by gonadotrophins and local cell-cell interactions. Stem cell factor (SCF) is one of the paracrine factors, produced by the Sertoli cells, involved in the local regulation of spermatogenesis. Measurement of its testicular level is important for addressing its role in testis physiopathology. However, the relative cell composition of experimental and pathological testis samples may lead to misinterpretation in relating SCF mRNA levels to the amount of RNA extracted from the whole tissue sample. Taking into account the relative RNA content of Sertoli cell origin should provide more significant data. In the present study, three sets of experiments were intended for modifying the proportion of RNA of Sertoli cell origin in RNA extracted from whole testis tissue samples: during postnatal development; following methoxy-acetic acid (MAA) administration; and after injecting a long-acting gonadotrophin-releasing hormone agonist (GnRHa). In a first step, we demonstrated clusterin mRNA level stability in purified Sertoli cell preparations between 20 days and adulthood, and following MAA or GnRHa treatment. In a second step, we used a competitive RT-PCR assay to measure SCF and clusterin mRNA levels and expressed the amount of SCF mRNA relative to the amount of clusterin mRNA under the above experimental conditions. The SCF/clusterin mRNA level ratio was found to remain roughly stable from 20 days post-partum to adulthood; i.e. during the development of spermatogenesis. MAA administration led to an overall increase in the SCF/clusterin mRNA level ratio between 7 and 14 days after administration, consistent with the replenishment of the testis with pachytene spermatocytes and round spermatids. Conversely, after long-acting GnRHa injection, the SCF/clusterin mRNA level ratio decreased only slightly from day 21 onward. Hence, the present studies indicate that, under physiopathological conditions, the amount of clusterin mRNA is a good marker of the amount of RNA of Sertoli cell origin in testis samples at day 20 or later; different experimental alterations of spermatogenesis are associated with different patterns of SCF mRNA levels; the relationship between FSH and SCF in vivo is not as simple as that described in vitro.

Expression of Oestrogen Receptors alpha and beta and of Aromatase in the Testis of Immature and Mature Boars

The boar testis secretes high amounts of oestrogens. In order to test for a likely local significance, we investigated the expression of oestrogen receptors (ER) in immature and mature boar testes using immunohistochemistry (IHC), in vitro and in situ reverse transcription-polymerase chain reaction (RT-PCR). Samples were from 25 boars castrated at ages of 50, 100, 150, 200 and 250 days. Mouse monoclonal primary antibodies against porcine ERalpha (clone HT227), human ERbeta1 (clone PPG5/10) and human P450 aromatase (clone SM1671P) were used. Expression of the mRNA was tested utilizing primers specific for the respective porcine mRNA sequences. ER immunoreactivity was exclusively localized to the nuclei. In immature boars, 90.6 +/- 1.2% of prespermatogonia and 71.0 +/- 2.6% of the Leydig cells showed a strong staining for ERalpha; 95.5 +/- 3.5% of the prespermatogonia but none of the Leydig and Sertoli cells were ERbeta-positive. In mature boars a strong staining for the ERbeta was observed in virtually all Sertoli, Leydig and germ cells, except for the elongating/ed spermatids, which were clearly negative; for the ERalpha, strong immunoreaction signals were restricted to spermatogonia and primary spermatocytes with 93.6 +/- 2.7% of these cells being positive; distinctly less intensive signals were observed in 51.4 +/- 0.27% of the secondary spermatocytes, round spermatids and Leydig cells. In vitro RT-PCR was positive for both receptors and results of in situ RT-PCR matched those obtained by IHC. P450 aromatase immunoreaction was restricted to the cytoplasm of Leydig cells. These findings suggest that testicular ER may be important factors contributing to onset and maintenance of spermatogenesis in the boar.

Postnatal changes in the expression of p60c-Src in mouse testes

Src family non-receptor tyrosine kinases are involved in signaling pathways which mediate cell growth, differentiation, transformation and tissue remodeling in various organs. In an effort to elucidate functional involvement of p60c-Src (c-Src) in spermatogenesis, the postnatal changes in c-src mRNA and c-Src protein together with kinase activity and subcellular localization were examined in mouse testes. c-src mRNA levels in testes increased during the first 2 weeks of postnatal development (PND). Following a decrease at puberty (PND 28), the c-src mRNA levels re-increased at adulthood (PND 50). Src kinase activity of testes was low at PND 7 but sharply increased prepubertally (PND 15) and highest at adulthood. Upon Western blotting, the level of c-Src protein was the highest in prepubertal testes but rather decreased in adult testes at PND 50. In adult testes, ubiquitination of c-Src proteins was apparent compared with immature one at PND 7, suggesting active turnover of c-Src by ubiquitination. In immature testes, c-Src immunoreactivity was largely found in the cytoplasm of the Sertoli cells. By contrast, in pubertal and adult testes intense immunoreactivity was localized at the adluminal and basal cytoplasm of Sertoli cells bearing elongated spermatids and early germ cells, respectively. The immunoreactivity of c-Src in the Leydig cells was increased during pubertal development, suggesting the functional involvement of c-Src in differentiated adult Leydig cells. Throughout postnatal development, some spermatogonia and spermatocytes showed intensive c-Src immunoreactivity compared with other germ cells, suggesting a possible role of c-Src in germ cell death. Taken together, it is suggested that c-Src may participate in the remodeling of the seminiferous epithelia and functional differentiation of Leydig cells during the postnatal development of mouse testes.

Cell junctions in the germinal epithelium may play an important role in spermatogenesis of the catfish P. fasciatum (Pisces, Siluriformes)

We identified adhesive junctions and gap junctions between Sertoli cells, between Sertoli and germ cells and between germ cells in the testis of P. fasciatum, a catfish of commercial relevance. To investigate the role of these junctions in spermatogenesis, as well as the molecular composition of the junctions, we performed an immunohistochemistry light microscopy as well as an immunogold labelling electron microscopy study with antibodies to adhesive and gap junctions proteins. Testes that were at different stages of spermatogenesis were used. Based on our morphological studies we speculate that Sertoli-germ and germ-germ cell adhesive junctions are important for maintaining the three-dimensional structure of the germinal cysts and an organized arrangement of the germ cells inside the cysts. Connexin 32 was identified in the germ cells and in the cysts walls. Our observations also suggest that Sertoli-germ and germ-germ cells gap junctions may be involved in the mechanism of synchronous development of germ cells.

Gal alpha 1,3Gal expression on porcine pancreatic islets, testis, spleen, and thymus

Gal alpha 1,3Gal (Gal) is the first target in antibody-mediated rejection of pig-to-non-human primate xenograft. Its expression may vary between organs and constituents of organs. Gal expression was studied in pancreas, testis, spleen and thymus of 22 pigs, with ages ranging from 1 to 22 months. The immunoperoxidase technique using the biotinylated lectin, Griffonia simplicifolia (IB4), was used. In the pancreas, neither endocrine (islet cells) nor exocrine cells expressed Gal. The Sertoli cells in the testis were negative. The spleen capsule and trabeculae did not stain for Gal, although both splenic T and B lymphocytes expressed Gal (B > T). Thymocytes were weakly positive, whereas thymic epithelial cells were negative for Gal. No age-related differences were seen in any tissues. Porcine islets of Langerhans, Sertoli cells, and the splenic and thymic structural frameworks did not express Gal, and therefore, should be relatively resistant to anti-Gal antibody-mediated rejection. The availability of pigs deficient in Gal as a source of islets may therefore not be beneficial in extending islet graft survival in non-human primate models.

Sertoli cell nodules in the undescended testis: a histochemical, immunohistochemical, and ultrastructural study of hyaline deposits

AIMS

To document the morphology, immunohistochemical staining properties, and ultrastructural features of hyaline material in Sertoli cell nodules of undescended testis and contrast them with those of sex cord tumour with annular tubules (SCTAT), which is histologically similar. To highlight the need to distinguish these nodules from other Sertoli cell hyperplasias, such as intratubular Sertoli cell proliferations, which occur in specific clinical contexts.

MATERIALS/METHODS

A retrospective study of 46 orchidectomy specimens from cryptorchid testes, 27 of which contained Sertoli cell nodules. Special histochemical stains, immunohistochemical stains for type IV collagen and fibronectin, and ultrastructural examination of the hyaline material were performed using tissue from paraffin wax embedded tissue blocks.

RESULTS

The hyaline deposits in SCTAT and Sertoli cell nodules had similar staining patterns-periodic acid Schiff (PAS) and PAS-diastase positivity with variable staining of Martius scarlet blue and Masson trichrome. Type IV collagen immunoreactivity was seen in hyaline areas, although fibronectin was negative. Electron microscopy of hyaline areas confirmed a compact matrix identical to components of the basement membrane in the adjacent seminiferous tubules.

CONCLUSION

This study describes an unusual form of Sertoli cell proliferation in undescended testes, which must be distinguished from Sertoli cell tumours and other forms of proliferation. In addition, the hyaline material within Sertoli cell nodules in the cryptorchid testis is histochemically, immunohistochemically, and ultrastructurally consistent with both matrix and fibrous components of seminiferous tubule basement membranes. Increased production of basement membrane material, with subsequent invagination into tubules, is the most likely origin of this material.

Characterization of tumour necrosis factor-alpha-related apoptosis-inducing ligand and its receptors in the adult human testis

Tumour necrosis factor-alpha-related apoptosis-inducing ligand (TRAIL) is a member of the tumour necrosis factor-alpha (TNF-alpha) family of cytokines which is known to induce apoptosis upon binding to its death domain-containing receptors, DR4/TRAIL-R1 and DR5/TRAIL-R2. Two additional TRAIL receptors, DcR1/TRAIL-R3 and DcR2/TRAIL-R4, lack functional death domains and act as decoy receptors for TRAIL. In this study, the presence of TRAIL and its receptors was investigated by immunohistochemistry in adult human testes. In addition, TRAIL and its receptors were studied in terms of protein and mRNA using western blot analysis and RT-PCR respectively. TRAIL and its receptors were immunodetected according to the different testicular cell types: TRAIL, DR5/TRAIL-R2 and DcR2/TRAIL-R4 were localized in Leydig cells, DR4/TRAIL-R1 was seen in peritubular and Sertoli cells whereas ligand and all receptors were detected in germ cells. Proteins and mRNA corresponding to TRAIL and its receptors were also identified in adult human testes. In conclusion, TRAIL and its receptors DR4/TRAIL-R1, DR5/TRAIL-R2, DcR1/TRAIL-R3 and DcR2/TRAIL-R4 are expressed in the human testis, and are predominantly localized in different germ cell types.

Expression of ghrelin and its functional receptor, the type 1a growth hormone secretagogue receptor, in normal human testis and testicular tumors

Ghrelin, the endogenous ligand for the GH secretagogue receptor (GHS-R), has been primarily linked to the central neuroendocrine regulation of GH secretion and food intake, although additional peripheral actions of ghrelin have also been reported. In this context, the expression of ghrelin and its cognate receptor has been recently demonstrated in rat testis, suggesting a role for this molecule in the direct control of male gonadal function. However, whether this signaling system is present in human testis remains largely unexplored. In this study we report the expression and cellular location of ghrelin and its functional receptor, the type 1a GHS-R, in adult human testis. In addition, evaluation of ghrelin and GHS-R1a immunoreactivity in testicular tumors and dysgenetic tissue is presented. The expression of the mRNAs encoding ghrelin and GHS-R1a was demonstrated in human testis specimens by RT-PCR, followed by direct sequencing. In normal testis, ghrelin immunostaining was demonstrated in interstitial Leydig cells and, at lower intensity, in Sertoli cells within the seminiferous tubules. In contrast, ghrelin was not detected in germ cells at any stage of spermatogenesis. The cognate ghrelin receptor showed a wider pattern of cellular distribution, with detectable GHS-R1a protein in germ cells, mainly in pachytene spermatocytes, as well as in somatic Sertoli and Leydig cells. Ghrelin immunoreactivity was absent in poorly differentiated Leydig cell tumor, which retained the expression of GHS-R1a peptide. In contrast, highly differentiated Leydig cell tumors expressed both the ligand and the receptor. The expression of ghrelin and GHS-R1a was also detected in dysgenetic Sertoli cell-only seminiferous tubules, whereas germ cell tumors (seminoma and embryonal carcinoma) were negative for ghrelin and were weakly positive for GHS-R1a. In conclusion, our results demonstrate that ghrelin and the type 1a GHS-R are expressed in adult human testis and testicular tumors. Overall, the expression of ghrelin and its functional receptor in human and rat testis, with roughly similar patterns of cellular distribution, is highly suggestive of a conserved role for this newly discovered molecule in the regulation of mammalian testicular function.

Distributional map of the terminal and sub-terminal sugar residues of the glycoconjugates in the prepubertal and postpubertal testis of a subject affected by complete androgen insensitivity syndrome (Morris's syndrome): lectin histochemical study

In the present research we have investigated the distribution of the sugar residues of the glycoconjugates in the prepubertal and postpubertal testes of a subject with Morris's syndrome (CAIS, Complete Androgen Insensitivity Syndrome). For this purpose a battery of six horseradish peroxidase-conjugated lectins was used (SBA, PNA, WGA, ConA, LTA and UEAI). We have obtained a complete distributional map of the terminal and sub-terminal oligosaccharides in the tunica albuginea, interstitial tissue, lamina propria of the seminiferous tubules, Leydig cells, Sertoli cells, spermatogonia, mastocytes and endothelial cells. Furthermore the present study has shown that a large amount of sugar residues were detectable in the prepubertal and postpubertal testes but that some differences exist with particular regard to the Sertoli cells. The Sertoli cells and the Leydig cells of the retained prepubertal testis of the patient affected by Morris's syndrome were characterized by the presence of alpha-L-fucose, which was absent in the retained prepubertal testis of the normal subjects. Comparing the results on the postpubertal testis with those obtained on the same aged testis of healthy subjects we have demonstrated that alpha-L-fucose in the Sertoli and Leydig cells and D-galactose-N-acetyl-D-galactosamine in the Leydig cells are a unique feature of the subject affected by Morris's syndrome. D-galactose (ss1,3)-N-acetyl-D-galactosamine and sialic acid, which are present in the Leydig cells of the normal testis were never observed in the same cells of the postpubertal testis of the CAIS patient.

Targeted expression of human FSH receptor Asp567Gly mutant mRNA in testis of transgenic mice: role of human FSH receptor promoter

AIM

To specifically express the Asp567Gly human follicle-stimulating hormone receptor (FSHR) under the control of its promoter to evaluate the phenotypic consequences in the presence of normal pituitary function.

METHODS

We produced transgenic mice overexpressing the Asp567Gly human FSHR under the control of a 1.5kb 5'-flanking region fragment of its promoter.

RESULTS

Mice were phenotypically normal and fertile. In males, mRNA could be detected in the testis and the brain, indicating that the 1.5kb promoter fragment drives expression not only in the gonads. The testis weight/body weight ratio and the testosterone levels in transgenic and non-transgenic littermates were similar. By in situ hybridisation we found that the transgenic FSHR was highly expressed in Sertoli cells, spermatocytes and round spermatids. However, a radioligand receptor assay failed to show a significant difference in total FSHR binding sites in testis homogenates of transgenic and wild type animals, suggesting that the transgenic FSHR is probably not translated into functional receptor protein.

CONCLUSION

A 1.5kb 5'-region of the human FSHR drives mRNA expression of the transgene in the testis but leads to ectopic expression in germ cells and in the brain. No phenotypic consequences could be documented due to the lack of protein expression.

Intratubular germ cell neoplasia of unclassified type occupying the whole testis accompanied by a small mature teratoma and metastatic choriocarcinoma and Sertoli cell-only tubules in the other testis

A 19-year-old man with mild mental retardation was diagnosed as having metastatic choriocarcinoma and a testicular tumor. Histopathological examination of the resected testis revealed the presence of a small lesion of mature teratoma but no trace of choriocarcinoma. The remaining seminiferous tubules were atrophic and lined by large atypical germ cells, which were diagnosed as intratubular germ cell neoplasia of the unclassified type (IGCNU). A small area with prominent tubules was also observed. Within this lesion, the tubules were dilated and contained several layers of cells with central necrosis. Immunohistological comparison of staining for several biological markers (Ki-67, c-kit and placental alkaline phosphatase) between cells in the atrophic tubules and those in the dilated tubules indicated a progression of the latter cells to cells with a more proliferative ability. In the opposite testis, examined at autopsy after death due to metastatic choriocarcinoma, all seminiferous tubules were lined by Sertoli cells only. It was therefore assumed that the germ cell tumor of the combined histological type had primarily arisen in the background of IGCNU, and that choriocarcinoma had spontaneously regressed. The early onset of these testicular neoplastic lesions strongly indicates their occurrence under the genetic background of gonadal dysplasia, the Sertoli cell-only syndrome. The possible relation of gonadal disease to mental retardation in this patient is also discussed.

Immunolocalization of PTHrP in prepubertal and pubertal testis of European bison

The present study deals with immunohistochemical localization of PTHrP in prepubertal and pubertal testis of European bison. PTHrP immunoreactivity was observed in germinal cells in the testis of both prepubertal and pubertal animals. In calves, PTHrP was found in germinal cells, in seminiferous tubules lacking the lumen. The reaction was strong and regularly distributed within the cytoplasm. In adult animals, the reaction showed differentiation in spermatogenic cells. Some cells were strongly and diffusely stained, others exhibited weaker reaction of granular pattern. Sertoli cells and Leydig cells were PTHrP-negative in calves and adult animals.

A Novel voltage-dependent chloride current activated by extracellular acidic pH in cultured rat Sertoli cells

Sertoli cells from mammalian testis are key cells involved in development and maintenance of stem cell spermatogonia as well as secretion of a chloride- and potassium-rich fluid into the lumen of seminiferous tubules. Using whole-cell patch clamp experiments, a novel chloride current was identified. It is activated only in the presence of an extracellular acidic pH, with an estimated half-maximal activation at pH 5.5. The current is strongly outwardly rectifying, activated with a fast time-dependent onset of activation but a slow time-dependent kinetic at depolarization pulses. The pH-activated chloride current was not detected at physiological or basic pH and is not sensitive to intracellular or extracellular Ca2+ variation. Diphenylamine-2-carboxylic acid and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid blocked the induced currents, and its anionic selectivity sequence was Cl- > Br- > I-> gluconate. We have performed a reverse transcription-PCR analysis to search for voltage-dependent chloride rClC channels in cultured rat Sertoli cells. Among the nine members of the family only rClC-2, rClC-3, rClC-6, and rClC-7 have been identified. The inwardly rectifying rClC-2 chloride current was activated by hyperpolarization but not by pH variation. A different depolarization-activated outwardly rectifying chloride current was activated only by hypotonic challenge and may correspond either to rClC-3 or rClC-6. Immunolocalization experiments demonstrate that rClC-7 resides in the intracellular compartment of Sertoli cells. This study provides the first functional identification of a native acid-activated chloride current. Based on our molecular analysis of rClC proteins, this new chloride current does not correspond to rClC-2, rClC-3, rClC-6, or rClC-7 channels. The potential physiological role of this native current in an epithelial cell from the reproductive system is discussed.

Expression of anti-Müllerian hormone mRNA during gonadal and follicular development in the brushtail possum (Trichosurus vulpecula)

The ontogeny of anti-Müllerian hormone (AMH) gene expression in the brushtail possum during formation of the ovary and growth of follicles was examined using in situ hybridization. For comparative purposes, the expression pattern of AMH was also examined in the developing testis. In the female, AMH mRNA was observed in the ovary of 50% (3/6) of pouch young collected around the time of sexual differentiation of the gonad (Days 1-5): the signal was predominately localized to the inner-cortical and outer-medullary region of the ovary. Thereafter, AMH mRNA was not observed in the developing ovary until Days 78-113 of postnatal life when follicles first formed at the cortical-medullary boundary. At this time, AMH mRNA was observed in the cuboidal granulosa cells of some early growing (i.e. transitional) follicles and in the granulosa cells of primary follicles. Thereafter, AMH mRNA was present in granulosa cells at all subsequent stages of follicular growth (i.e. primary through antral), but not in preovulatory follicles. In all cases, once follicles had formed, AMH mRNA was limited to the granulosa cells and was not observed in the surface epithelium, stromal cells, oocytes, theca, corpus luteum, medullary cords, rete or interstitial glands. In the possum testis, Sertoli cells strongly expressed AMH around the time of sexual differentiation of the gonad, but expression decreased to very low levels in adults, suggesting that AMH plays a similar role in brushtail possums to that observed in other mammalian species. In conclusion, localization of mRNA for AMH exclusively to granulosa cells of growing follicles in the brushtail possum is consistent with a central role for this hormone in control of granulosa cell function in marsupials. In addition, expression of AMH in the developing ovary around the time of morphological sexual differentiation raises intriguing questions regarding the possible role of AMH at this time.

Transcription factor GATA-6, cell proliferation, apoptosis, and apoptosis-related proteins Bcl-2 and Bax in human fetal testis

The GATA family of transcription factors have been implicated in regulating the development and function of many organs. Furthermore, they have been linked to signaling cascades regulating cell fate through apoptosis. GATA-6 has been shown to be expressed in the gonads, but its cell-specific expression in the testis has remained unclear. We have studied GATA-6 expression in human fetal testis using in situ hybridization and immunohistochemistry and compared these results with the expression of the apoptosis-related proteins Bcl-2 and Bax. Furthermore, apoptosis was studied by thymidine deoxyribose-mediated deoxy-UTP nick end labeling assay, and cell proliferation by Ki-67 immunohistochemistry. GATA-6 mRNA and protein were expressed in Sertoli and Leydig cells early in gestation. Apoptotic cells were scanty between wk 16 and 40, and proliferation significantly ceased during the third trimester, supporting the view that only a little tissue remodeling occurs in the late fetal testis. Bax was present throughout the fetal period, whereas Bcl-2 expression decreased toward term. Neither of these factors correlated to the extent of apoptosis, and thus their role in the regulation of apoptosis in the fetal testis remains open. Despite strong expression, GATA-6 did not correlate with apoptosis or cell proliferation and is therefore unlikely to be directly involved in these processes in the human fetal testis.

Rab8B GTPase and junction dynamics in the testis

Throughout spermatogenesis, germ cells migrate from the basal to the adluminal compartment while remaining attached to Sertoli cells via actin-based adherens and intermediate filament-based anchoring junctions. However, the events that trigger deadhesion and adhesion remain largely unknown. As part of our continued effort in elucidating the mechanism of germ cell movement, we have examined the role of Rab8B, a GTPase probably participating in intracellular trafficking events at the site of the adherens junction. By RT-PCR Rab8B mRNA was found in the brain, testis, heart, kidney, and spleen. Immunohistochemical studies revealed that Rab8B was concentrated predominantly in the basal compartment, localizing to a similar site at which immunoreactive E-cadherin was found. Additional experiments demonstrated that Rab8B associated with the actin, intermediate filament, and microtubule cytoskeletal networks. When Sertoli cells were cultured at high density or germ cells were cocultured with Sertoli cells, Rab8B increased significantly during junction assembly. Moreover, inclusion of germ cell-conditioned medium in Sertoli cell cultures resulted in stimulation of Rab8B expression. Conversely, treatment of adult rats with 1-(2,4-dichlorobenzyl)-indazole-3-carbohydrazide reduced Rab8B mRNA and protein levels, coinciding with the time of germ cell loss from the epithelium. Taken collectively, these studies suggest that Rab8B participates in adherens junction dynamics in the testis.

Cres2 and Cres3: new members of the cystatin-related epididymal spermatogenic subgroup of family 2 cystatins

The cystatin-related epididymal spermatogenic (CRES) and recently identified testatin and cystatin T proteins define a new subgroup within the family 2 cystatins of cysteine protease inhibitors. Members of the CRES subgroup are predominantly expressed in reproductive tissues and lack critical cystatin active-site sequences implying divergent functions. To determine whether there are additional members of the subgroup, we searched nucleotide databases and identified two novel genes that we designated Cres2 and Cres3. These genes, like other subgroup members, encode proteins with four conserved cysteine residues and predicted molecular weights characteristic of family 2 cystatins but have divergent cystatin inhibitory sequences. Furthermore, the genes exhibited reproductive-specific expression with Cres2 exclusively expressed in the epithelial cells of the proximal and midcaput epididymal regions and Cres3 expressed in the proximal caput epididymal epithelium, Sertoli cells of the testis, and early follicles and corpora lutea in the ovary. Additional studies showed that, like Cres, both Cres2 and Cres3 genes are dependent on testicular factors for epididymal expression. Taken together, CRES2 and CRES3 represent new members of a subgroup of cystatin family 2 proteins that likely carry out tissue-specific functions distinct from that of typical cystatins.

Sertoli cell-induced adult rat islet beta-cell mitogenesis: causative pathways

We have previously observed that in vitro co-incubation of rat pre-pubertal Sertoli cells (SC), or their dialyzed/concentrated secretory products with homologous islets, resulted in significant stimulation of the islet beta-cell mitotic index. Aim of the present work was to assess both the specificity and nature of the mechanisms underlying this phenomenon. For this purpose, first we tested astrocytes (AA), separated and purified from the rat brain cortex, where they are known to release a number of growth factors and neurotrophic cytokines, for co-incubation with the islets. However, under the same experimental conditions used for SC, AA did not induce any changes in the beta-cell life cycle, thereby confirming specificity of SC, with respect to induction of beta-cell mitogenicity. For the second purpose, we examined the products of PD-1, a gene located in the cytoplasm of SC, where it promotes spermatogenesis. By blocking the protein encoded by PD-1, under appropriate culture conditions, we observed that the SC-induced increase in beta-cell mitotic activity lost its statistical significance, which suggested a role of PD-1 with respect to SC-related mitogenic properties on beta-cells. These findings corroborate the idea that SC, by either direct contact, or by means of their secretory products, clearly affect the islet beta-cell mitotic rate. Preliminarily, PD-1 gene, located in the cytoplasm of SC, might be one of the factors involved with the induction of beta-cell mitotic activity. In conclusion, SC-induced beta-cell mitotic activity is specific, seemingly mediated by humoral factors whose acting mechanisms have started being unfolded.

The interplay of collagen IV, tumor necrosis factor-alpha, gelatinase B (matrix metalloprotease-9), and tissue inhibitor of metalloproteases-1 in the basal lamina regulates Sertoli cell-tight junction dynamics in the rat testis

During spermatogenesis, preleptotene and leptotene spermatocytes must translocate across the blood-testis barrier formed by inter-Sertoli cell-tight junctions (TJs) from the basal compartment of the seminiferous epithelium adjacent to the basement membrane to the adluminal compartment at stages VIII-IX for further development. Because of the close proximity between extracellular matrix (ECM) that constitutes the basement membrane and the blood-testis barrier, we sought to investigate the role of ECM in Sertoli cell TJ dynamics. When Sertoli cells were cultured in vitro to initiate the assembly of the Sertoli cell TJ-permeability barrier, the presence of an anticollagen IV antibody indeed perturbed the barrier. Because ECM is known to maintain a pool of cytokines and TNFalpha has been shown to regulate TJ dynamics in other epithelia, we investigated whether TNFalpha can regulate Sertoli cell TJ function via its effects on collagen alpha3(IV) and other proteins that maintain the homeostasis of ECM. As expected, recombinant TNFalpha perturbed the Sertoli cell TJ-barrier assembly in vitro dose dependently. TNFalpha also inhibited the timely induction of occludin, which is known to associate with the Sertoli cell TJ-barrier assembly. Furthermore, TNFalpha induced the expression of Sertoli cell collagen alpha3(IV), gelatinase B (matrix metalloprotease-9, MMP-9) and tissue inhibitor of metalloproteases-1 but not gelatinase A (matrix metalloprotease-2), and promoted the activation of pro-MMP-9. These results thus suggest that the activated MMP-9 induced by TNFalpha is used to cleave the existing collagen network in the ECM, thereby perturbing the TJ-barrier. This in turn creates a negative feedback that causes TNFalpha to induce collagen alpha3(IV) and tissue inhibitor of metalloproteases-1 expression so as to replenish the collagen network in the disrupted TJ-barrier and limit the activity of MMP-9. Taken collectively, these observations strengthen the notion that ECM is involved in the regulation of junction dynamics in addition to its structural role in the testis.

Multidrug resistance genes and p-glycoprotein in the testis of the rat, mouse, Guinea pig, and human

Study of the multidrug resistance phenomenon in tumor cell lines has led to the discovery of the product of the multidrug resistance (MDR) type 1 genes, the plasma membrane P-glycoprotein (P-gp) that functions as an energy-dependent pump for the efflux of diverse anticancer drugs. P-gp was also recently identified in normal epithelial cells with secretory/excretory functions and in the endothelial cells of the capillary blood vessels in the brain and the testis. These endothelial cells are key elements of the blood-brain and blood-testis barriers, respectively. The aim of this study, in the rat, mouse, guinea pig, and human, was to determine whether testicular cells other than the capillary endothelial cells could express MDR type I genes. Immunohistochemistry on testicular sections revealed that P-gp is present in interstitial cells in the mouse, rat, and human testes, in early and late spermatids in guinea pig testis, and in late spermatids in the rat, mouse, and human. Reverse transcription-polymerase chain reaction analysis on isolated mouse, rat, and human cells showed that all somatic testicular cells (Leydig cells, macrophages, peritubular cells, and Sertoli cells) and the cytoplasmic lobes from rat late spermatids expressed MDR type I mRNAs, whereas spermatogonia, pachytene spermatocytes, and early spermatids did not. An ontogenesis study in the mouse reveals that type I MDR gene expression begins at 13.5 days postcoitum at the time when the seminiferous cords and the blood vessels appear and are maintained thereafter. Finally, two functional tests on isolated rat cells, the doxorubicin and rhodamine uptake assays, demonstrated that rat testicular macrophages, Leydig cells, peritubular cells, and Sertoli cells displayed a multidrug-resistance activity, whereas spermatogonia, pachytene spermatocytes, and early spermatids did not. Western blot experiments have revealed that a P-gp of 175 kDa is present in the human testis as well as in the rat Leydig cells, testicular macrophages, peritubular cells, and Sertoli cells, but is absent in spermatogonia, spermatocytes, and early spermatids. We conclude that P-gp is involved in the self-protection of the somatic cells and is most probably one of the molecules that confers its functionality to the blood-testis barrier. The absence of expression of MDR type I genes in mitotic and meiotic germ cells probably explains their particular vulnerability to various anticancer drugs. In contrast, expression of the P-gp in the haploid cells most likely reflects the ability of spermatozoa to assume their own antidrug defense.