The rat Tspy is preferentially expressed in elongated spermatids and interacts with the core histones

Potential dual functional roles of the Y-linked RBMY in hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is a highly heterogeneous liver cancer with significant male biases in incidence, disease progression, and outcomes. Previous studies have suggested that genes on the Y chromosome could be expressed and exert various male‐specific functions in the oncogenic processes. In particular, the RNA‐binding motif on the Y chromosome (RBMY) gene is frequently activated in HCC and postulated to promote hepatic oncogenesis in patients and animal models. In the present study, immunohistochemical analyses of HCC specimens and data mining of The Cancer Genome Atlas (TCGA) database revealed that high‐level RBMY expression is associated with poor prognosis and survival of the patients, suggesting that RBMY could possess oncogenic properties in HCC. To examine the immediate effect(s) of the RBMY overexpression in liver cancer cells, cell proliferation was analyzed on HuH‐7 and HepG2 cells. The results unexpectedly showed that RBMY overexpression inhibited cell proliferation in both cell lines as its immediate effect, which led to vast cell death in HuH‐7 cells. Transcriptome analysis showed that genes involved in various cell proliferative pathways, such as the RAS/RAF/MAP and PIP3/AKT signaling pathways, were downregulated by RBMY overexpression in HuH‐7 cells. Furthermore, in vivo analyses in a mouse liver cancer model using hydrodynamic tail vein injection of constitutively active AKT and RAS oncogenes showed that RBMY abolished HCC development. These findings support the notion that Y‐linked RBMY could serve dual tumor‐suppressing and tumor‐promoting functions, depending on the spatiotemporal and magnitude of its expression during oncogenic processes, thereby contributing to sexual dimorphisms in liver cancer.

Spermatogonial Stem Cells for In Vitro Spermatogenesis and In Vivo Restoration of Fertility

Spermatogonial stem cells (SSCs) are the only adult stem cells capable of passing genes onto the next generation. SSCs also have the potential to provide important knowledge about stem cells in general and to offer critical in vitro and in vivo applications in assisted reproductive technologies. After century-long research, proof-of-principle culture systems have been introduced to support the in vitro differentiation of SSCs from rodent models into haploid male germ cells. Despite recent progress in organotypic testicular tissue culture and two-dimensional or three-dimensional cell culture systems, to achieve complete in vitro spermatogenesis (IVS) using non-rodent species remains challenging. Successful in vitro production of human haploid male germ cells will foster hopes of preserving the fertility potential of prepubertal cancer patients who frequently face infertility due to the gonadotoxic side-effects of cancer treatment. Moreover, the development of optimal systems for IVS would allow designing experiments that are otherwise difficult or impossible to be performed directly in vivo, such as genetic manipulation of germ cells or correction of genetic disorders. This review outlines the recent progress in the use of SSCs for IVS and potential in vivo applications for the restoration of fertility.

Comparison of Y-chromosome-linked TSPY, TSPY2, and PRAMEY genes in Taurus cattle, yaks, and interspecific hybrid bulls

Domestic yaks (Bos grunniens) and domestic Taurus cattle (Bos taurus) are closely related. An interesting phenomenon in interspecific crossings is male sterility in the F₁ hybrid (yattle) and F₂ backcross, with no late meiotic cells or spermatids in the seminiferous tubules. The mammalian Y chromosome is crucial for spermatogenesis and male fertility. This study investigated the copy number variations and mRNA of Y-transitional region genes TSPY2 (testis specific protein, Y-linked 2 and testis-specific Y-encoded protein 3-like) and PRAMEY (preferentially expressed antigen in melanoma, Y-linked), and Y-ampliconic region genes TSPY (testis-specific Y-encoded protein 1-like), ZNF280BY (zinc finger protein 280B, Y-linked) and HSFY (heat-shock transcription factor, Y-linked) in mature testes from Taurus cattle, yaks, and yattle. Phylogenetic trees divided 33 copies of TSPY into major 2 types (TSPY-T1 and TSPY-T2), 19 copies of TSPY2 into 2 types (TSPY2-T1 and T2), and 8 copies of PRAMEY into 4 types (PRAMEY-T1 to T4). Searching by the Basic Local Alignment Search Tool of the TSPY2 coding sequences in GenBank revealed that TSPY2 was conserved in Bovidae. The TSPY2-T2 sequences were absent, whereas PRAMEY-T2 and PRAMEY-T4 were amplified on the yak Y chromosome. The average copy numbers of TSPY-T2 and ZNF280BY were significantly different between cattle and yaks. The TSPY-T2, TSPY2, PRAMEY, ZNF280BY, and HSFY genes were uniquely or predominantly expressed in testes. Reverse-transcription quantitative PCR showed that the TSPY-T2, PRAMEY-T2, HSFY, ZNF280BY, protamine 1 (PRM1), and protamine 2 (PRM2) genes were almost not expressed in yattle. The PRM1 and PRM2 genes are used as positive markers for spermatozoa. Thus, our results showed that the genomic structure of the Y-transitional and Y-ampliconic region differed between Taurus cattle and yaks. Dysregulated expression of Y-ampliconic region genes TSPY-T2, HSPY, ZNF280BY, and Y-transitional region gene PRAMEY-T2 may be associated with hybrid male sterility in yattle.

Prostate cancer susceptibility and growth linked to Y chromosome genes

The role of Y chromosome in prostate cancer progression and incidence is not well known. Among the 46 chromosomes, Y chromosome determines the male gender. The Y chromosome is smaller than the X chromosome and contains only 458 genes compared to over 2000 genes found in the X chromosome. The Y chromosome is prone to high mutation rates, created exclusively in sperm cells due to the highly oxidative environment of the testis. Y chromosome harbors epigenetic information, which affects the expression of genes associated with the incidence and progression of prostate cancer. In this review, we focus on Y chromosome related genetic abnormalities, likely to be involved in the development and progression of prostate cancer.

Human spermatogonial markers

In this review, we provide an up-to-date compilation of published human spermatogonial markers, with focus on the three nuclear subtypes A_dark, A_pale and B. In addition, we have extended our recently published list of putative spermatogonial markers with protein expression and RNA-sequencing data from the Human Protein Atlas and supported these by literature evidence. Most importantly, we have put substantial effort in acquiring a comprehensive list of new and potentially interesting markers by refiltering the raw data of 15 published germ cell expression datasets (four human, eleven rodent) and subsequent building of intersections to acquire a robust, cross-species set of spermatogonia-enriched or -specific transcripts.

Roles of the Y chromosome genes in human cancers

Male and female differ genetically by their respective sex chromosome composition, that is, XY as male and XX as female. Although both X and Y chromosomes evolved from the same ancestor pair of autosomes, the Y chromosome harbors male-specific genes, which play pivotal roles in male sex determination, germ cell differentiation, and masculinization of various tissues. Deletions or translocation of the sex-determining gene, SRY, from the Y chromosome causes disorders of sex development (previously termed as an intersex condition) with dysgenic gonads. Failure of gonadal development results not only in infertility, but also in increased risks of germ cell tumor (GCT), such as gonadoblastoma and various types of testicular GCT. Recent studies demonstrate that either loss of Y chromosome or ectopic expression of Y chromosome genes is closely associated with various male-biased diseases, including selected somatic cancers. These observations suggest that the Y-linked genes are involved in male health and diseases in more frequently than expected. Although only a small number of protein-coding genes are present in the male-specific region of Y chromosome, the impacts of Y chromosome genes on human diseases are still largely unknown, due to lack of in vivo models and differences between the Y chromosomes of human and rodents. In this review, we highlight the involvement of selected Y chromosome genes in cancer development in men.

Expression of a Y-located human proto-oncogene TSPY in a transgenic mouse model of prostate cancer

BACKGROUND

The human TSPY is the putative gene for the gonadoblastoma locus on the Y chromosome (GBY). Various molecular, pathological and transgenic mouse studies suggest that TSPY is a Y-located proto-oncogene contributing to the initiation/progression in human cancers, including germ cell tumors and various somatic cancers, such as prostate and liver cancer, and melanoma. The TgTSPY9 transgenic mouse line harbors a 8.2-kb human TSPY structural gene, which is tandemly integrated in the mouse Y chromosome, and expressed in a similar pattern as that of the endogenous gene in the human genome. This mouse model of human TSPY gene offers an opportunity to examine its behavior and potential contribution in various mouse models of human diseases, such as human cancers. We had investigated the expression of such TSPY-transgene in the LADY mouse model of prostate cancer, harboring a SV40 T antigen gene directed by a rat probasin promoter; and compared the expression pattern with those of endogenous TSPY gene and biomarkers in human prostate cancer specimens.

RESULTS

By introducing the Y-located TSPY-transgene to the LADY mice, we had examined the expression pattern of the human TSPY during prostatic oncogenesis in this mouse model of prostate cancer. Our results showed that the TSPY-transgene was activated in selected areas of the hypercellular stroma but not in the intraepithelial cells/neoplasia in the prostates of TgTSPY9/LADY mice. Using a specific biomarker, FOXA1, for epithelial cells, we demonstrated that TSPY-positive cells proliferated exclusively in the cancerous stroma in the LADY model at late stages of tumorigenesis. In contrast, in the human situation, TSPY was predominantly co-expressed with FOXA1 in the epithelial cells of PIN lesions and FOXA1 and another cancer biomarker, AMACR, in the adenocarcinoma cells in clinical prostate cancer samples of various degrees of malignancy.

CONCLUSIONS

Our data show that human TSPY could be abnormally activated during prostatic oncogenesis, and could possibly contribute to the heterogeneity of prostate cancer. The differential expression patterns of the human TSPY between the LADY mouse model and clinical prostate cancer suggest potential limitations of current mouse models for studies of either TSPY behavior in diseased conditions or prostate cancer development.

A fresh look at the male-specific region of the human Y chromosome

The Chromosome-centric Human Proteome Project (C-HPP) aims to systematically map the entire human proteome with the intent to enhance our understanding of human biology at the cellular level. This project attempts simultaneously to establish a sound basis for the development of diagnostic, prognostic, therapeutic, and preventive medical applications. In Iran, current efforts focus on mapping the proteome of the human Y chromosome. The male-specific region of the Y chromosome (MSY) is unique in many aspects and comprises 95% of the chromosome's length. The MSY continually retains its haploid state and is full of repeated sequences. It is responsible for important biological roles such as sex determination and male fertility. Here, we present the most recent update of MSY protein-encoding genes and their association with various traits and diseases including sex determination and reversal, spermatogenesis and male infertility, cancers such as prostate cancers, sex-specific effects on the brain and behavior, and graft-versus-host disease. We also present information available from RNA sequencing, protein-protein interaction, post-translational modification of MSY protein-coding genes and their implications in biological systems. An overview of Human Y chromosome Proteome Project is presented and a systematic approach is suggested to ensure that at least one of each predicted protein-coding gene's major representative proteins will be characterized in the context of its major anatomical sites of expression, its abundance, and its functional relevance in a biological and/or medical context. There are many technical and biological issues that will need to be overcome in order to accomplish the full scale mapping.

Sequence recombination in exon 1 of the TSPY gene in men with impaired fertility

AIM

The aim of this study was to evaluate TSPY (testis specific protein on the Y chromosome) gene and 5'UTR (UnTranslated Region) polymorphisms in men with impaired fertility compared to fertile controls.

METHODS

We analyzed 72 infertile men and 31 fertile controls usingconventional sequencing analysis to find crucial SNPs (single nucleotide polymorphism) and other changes.

RESULTS

The most remarkable changes were found in the 1(st) exon only. In one half of the both infertile men and fertile controls, the most frequent finding was 26 SNPs with a similar pattern. In the other half we found highly relevant changes, generating a stop codon in the first third of exon 1. Early termination cut down the protein by 78.5%. This kind of change was not found in the fertile controls. No correlation was found between the spermiogram and the changes leading to the stop codon. The distribution of men with deletions, insertion and higher gene copy number was not statistically different.

CONCLUSION

The changes found in exon 1 in infertile men could fundamentally affect the process of spermatogenesis. These findings could significantly enhance our understanding of the molecular-genetic causes of male infertility.

Transcriptional dynamics of the sex chromosomes and the search for offspring sex-specific antigens in sperm

The ability to pre-select offspring sex via separation of X- and Y-bearing sperm would have profound ramifications for the animal husbandry industry. No fully satisfactory method is as yet available for any species, although flow sorting is commercially viable for cattle. The discovery of antigens that distinguish X- and Y-bearing sperm, i.e. offspring sex-specific antigens (OSSAs), would allow for batched immunological separation of sperm and thus enable a safer, more widely applicable and high-throughput means of sperm sorting. This review addresses the basic processes of spermatogenesis that have complicated the search for OSSAs, in particular the syncytial development of male germ cells, and the transcriptional dynamics of the sex chromosomes during and after meiosis. We survey the various approaches taken to discover OSSA and propose that a whole-genome transcriptional approach to the problem is the most promising avenue for future research in the field.

Role of the Y-located putative gonadoblastoma gene in human spermatogenesis

The gonadoblastoma locus on the human Y chromosome (GBY) is postulated to serve normal functions in spermatogenesis, but could exert oncogenic properties in predisposing susceptible germ cells to tumorigenesis in incompatible niches such as streaked gonads in XY sex reversed patients or dysfunctional testis in males. The testis-specific protein Y-linked (TSPY) repeat gene has recently been demonstrated to be the putative gene for GBY, based on its location on the GBY critical region, expression patterns in early and late stages of gonadoblastoma and ability to induce gonadoblastoma-like structures in the ovaries of transgenic female mice. Over-expression of TSPY accelerates G(2)/M progression in the cell cycle by enhancing the mitotic cyclin B-CDK1 kinase activities. Currently the normal functions of TSPY in spermatogenesis are uncertain. Expression studies of TSPY, and its X-homologue, TSPX, in normal human testis suggest that TSPY is co-expressed with cyclin B1 in spermatogonia and various stages of spermatocytes while TSPX is principally expressed in Sertoli cells in the human testis. The co-expression pattern of TSPY and cyclin B1 in spermatogonia and spermatocytes suggest respectively that 1) TSPY is important for male spermatogonial cell replication and renewal in the testis; and 2) TSPY could be a catalyst/meiotic factor essential for augmenting the activities of cyclin B-cyclin dependent kinases, important for the differentiation of the spermatocytes in prophase I and in preparation for consecutive rounds of meiotic divisions without an intermediate interphase during spermatogenesis.

TSPY and Male Fertility

Spermatogenesis requires the concerted action of thousands of genes, all contributing to its efficiency to a different extent. The Y chromosome contains several testis-specific genes and among them the AZF region genes on the Yq and the TSPY1 array on the Yp are the most relevant candidates for spermatogenic function. TSPY1 was originally described as the putative gene for the gonadoblastoma locus on the Y (GBY) chromosome. Besides its oncogenic properties, expression analyses in the testis and in vitro and in vivo studies all converge on a physiological involvement of the TSPY1 protein in spermatogenesis as a pro-proliferative factor. The majority of TSPY1 copies are arranged in 20.4 kb of tandemly repeated units, with different copy numbers among individuals. Our recent study addressing the role of TSPY1 copy number variation in spermatogenesis reported that TSPY1 copy number influences spermatogenic efficiency and is positively correlated with sperm count. This finding provides further evidence for a role of TSPY1 in testicular germ cell proliferation and stimulates future research aimed at evaluating the relationship between the copy number and the protein expression level of the TSPY1 gene.

Transgenic Mouse Studies to Understand the Regulation, Expression and Function of the Testis-Specific Protein Y-Encoded (TSPY) Gene

The TSPY gene, which encodes the testis-specific protein, Y-encoded, was first discovered and characterized in humans, but orthologous genes were subsequently identified on the Y chromosome of many other placental mammals. TSPY is expressed in the testis and to a much lesser extent in the prostate gland, and it is assumed that TSPY serves function in spermatogonial proliferation and/or differentiation. It is further supposed that TSPY is involved in male infertility and exerts oncogenic effects in gonadal and prostate tumor formation. As a member of the TSPY/SET/NAP protein family, TSPY is able to bind cyclin B types, and stimulates the cyclin B1-CDK1 kinase activity, thereby accelerating the G₂/M phase transition of the cell cycle of target cells. Because the laboratory mouse carries only a nonfunctional Y-chromosomal Tspy-ps pseudogene, a knockout mouse model for functional research analyses is not a feasible approach. In the last decade, three classical transgenic mouse models have been developed to contribute to our understanding of TSPY regulation, expression and function. The different transgenic mouse approaches and their relevance for studying TSPY regulation, expression and function are discussed in this review.

Gonadoblastoma locus and the TSPY gene on the human Y chromosome

The gonadoblastoma (GBY) locus is the only oncogenic locus on the human Y chromosome. It is postulated to serve a normal function in the testis, but could exert oncogenic effects in dysgenetic gonads of individuals with intersex and/or dysfunctional testicular phenotypes. Recent studies establish the testis-specific protein Y-encoded (TSPY) gene to be the putative gene for GBY. TSPY serves normal functions in male stem germ cell proliferation and differentiation, but is ectopically expressed in early and late stages of gonadoblastomas, testicular carcinoma in situ (the premalignant precursor for all testicular germ cell tumors), seminomas, and selected nonseminomas. Aberrant TSPY expression stimulates protein synthetic activities, accelerates cell proliferation, and promotes tumorigenicity in athymic mice. TSPY binds to type B cyclins, enhances an activated cyclin B-CDK1 kinase activity, and propels a rapid G(2)/M transition in the cell cycle. TSPY also counteracts the normal functions of its X-homologue, TSPX, which also binds to cyclin B and modulates the cyclin B-CDK1 activity to insure a proper G(2)/M transition in the cell cycle. Hence, ectopic expression and actions of the Y-located TSPY gene in incompatible germ cells, such as those in dysgenetic or ovarian environments and dysfunctional testis, disrupt the normal cell cycle regulation and predispose the host cells to tumorigenesis. The contrasting properties of TSPY and TSPX suggest that somatic cancers, such as intracranial germ cell tumors, melanoma, and hepatocellular carcinoma, with detectable TSPY expression could exhibit sexual dimorphisms in the initiation and/or progression of the respective oncogenesis.

CABS1 is a novel calcium-binding protein specifically expressed in elongate spermatids of mice

Single intraperitoneal injection of busulfan at 20 mg/kg body weight to mature male mice induced the deletion of the spermatogenic cells, followed by the restoration of the spermatogenesis by the surviving undifferentiated spermatogonia. The changes of the protein contents in testis during these processes were analyzed by two-dimensional gel electrophoresis in order to identify the proteins expressed at the specific stages of spermatogenesis. An acidic protein that disappeared and recovered in the same time course as spermatids after the busulfan treatment was identified as CABS1 by mass spectrometry. It was found that CABS1 was specifically expressed in the elongate spermatids at steps 13 to 16 in stages I to VIII of the seminiferous epithelium cycle of the mouse, and then it localized to the principal piece of flagellum of the mature sperm in the cauda epididymis. We have found for the first time that CABS1 is a calcium-binding protein that binds calcium during the maturation in the epididymis.

The human Y-encoded testis-specific protein interacts functionally with eukaryotic translation elongation factor eEF1A, a putative oncoprotein

Testis-specific protein Y-encoded (TSPY) is the putative gene for the gonadoblastoma locus on the Y chromosome. TSPY is expressed in normal germ cells of fetal and adult testis and ectopically in tumor germ cells, including gonadoblastoma in intersex patients, testicular germ cell tumors, prostate cancer and other somatic cancers. It is a member of the TSPY/SET/NAP1 superfamily and harbors a highly conserved domain, termed SET/NAP domain. To explore its possible role(s) in tumorigenesis, we had performed a yeast two-hybrid screen of a fetal gonadal cDNA library and identified the translation elongation factor eEF1A as a binding partner for TSPY at the SET/NAP domain. TSPY and eEF1A were highly expressed and colocalized in tumor germ cells of human seminoma specimens, suggesting their possible interaction in germ cell tumors. They were colocalized in the cytoplasm and could be co-immunoprecipitated from transfected COS7 cells. Significantly, both eEF1A1 and eEF1A2 have postulated to be involved in various types of human cancer, including breast and prostate cancers. TSPY enhanced protein synthesis of a reporter gene, which was augmented by an overexpression of eEF1A. TSPY also increased the nuclear redistribution of eEF1A, resulting in a parallel increase in reporter gene transcripts. Our results suggest that TSPY could exert its oncogenic function(s) by interacting with eEF1As and stimulating gene expression via its enhancements in protein synthesis and gene transcription.

A new cause of male infertility after cisplatin exposure: the effect of cisplatin on Y chromosomes

OBJECTIVES

To investigate the impact of cisplatin (CP) on the testes-specific protein, Y-linked (TSPY) gene situated on the Y chromosome.

METHODS

The control group consisted of 10 rats. Group IIA consisted of 15 rats that underwent orchiectomy and received three cycles of 1 mg/kg, 2.5 mg/kg, or 5 mg/kg CP. Group IIB was exposed to the same doses of three cycles of chemotherapy but was examined after 3 months of chemotherapy. Group III was exposed to the same doses of chemotherapy without initial orchiectomy. Reverse transcriptase polymerase chain reaction for TSPY messenger ribonucleic acid (mRNA) and immunohistochemical staining for histone 2B were performed on the testes. Results were evaluated by one-way analysis of variance.

RESULTS

Compared with the controls, the expression of TSPY mRNA in Group IIA after exposure to 1 mg/kg CP did not change; however, mRNA levels after exposure to 2.5 mg/kg and 5 mg/kg CP were decreased by 40% and 78%, respectively. In Group III after exposure to the same doses of CP, mRNA levels decreased by 30%, 87.5%, and 88%, respectively. The expression of TSPY was at normal levels except in rats that received 5 mg/kg CP in Group IIB. Immunohistochemical study revealed that histone 2B expression was decreased in a dose-dependent manner. None of the rats from any of the groups died during the study period.

CONCLUSIONS

Decreased TSPY expression after CP exposure might be another mechanism for male infertility.