Organization and expression of bovine TSPY

State of the art on the physical mapping of the Y-chromosome in the <i>Bovidae</i> and comparison with other species

The next generation sequencing has significantly contributed to clarify the genome structure of many species of zootechnical interest. However, to date, some portions of the genome, especially those linked to a heterogametic nature such as the Y chromosome, are difficult to assemble and many gaps are still present. It is well known that the fluorescence in situ hybridization (FISH) is an excellent tool for identifying genes unequivocably mapped on chromosomes. Therefore, FISH can contribute to the localization of unplaced genome sequences, as well as to correct assembly errors generated by comparative bioinformatics. To this end, it is necessary to have starting points; therefore, in this study, we reviewed the physically mapped genes on the Y chromosome of cattle, buffalo, sheep, goats, pigs, horses and alpacas. A total of 208 loci were currently mapped by FISH. 89 were located in the male-specific region of the Y chromosome (MSY) and 119 were identified in the pseudoautosomal region (PAR). The loci reported in MSY and PAR were respectively: 18 and 25 in Bos taurus, 5 and 7 in Bubalus bubalis, 5 and 24 in Ovis aries, 5 and 19 in Capra hircus, 10 and 16 in Sus scrofa, 46 and 18 in Equus caballus. While in Vicugna pacos only 10 loci are reported in the PAR region. The correct knowledge and assembly of all genome sequences, including those of genes mapped on the Y chromosome, will help to elucidate their biological processes, as well as to discover and exploit potentially epistasis effects useful for selection breeding programs.

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.

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.

Determination of sex origin of meat and meat products on the DNA basis: a review

Sex determination of domestic animal's meat is of potential value in meat authentication and quality control studies. Methods aiming at determining the sex origin of meat may be based either on the analysis of hormone or on the analysis of nucleic acids. At the present time, sex determination of meat and meat products based on hormone analysis employ gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography-mass spectrometry/mass spectrometry (HPLC-MS/MS), and enzyme-linked immunosorbent assay (ELISA). Most of the hormone-based methods proved to be highly specific and sensitive but were not performed on a regular basis for meat sexing due to the technical limitations or the expensive equipments required. On the other hand, the most common methodology to determine the sex of meat is unquestionably traditional polymerase chain reaction (PCR) that involves gel electrophoresis of DNA amplicons. This review is intended to provide an overview of the DNA-based methods for sex determination of meat and meat products.

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.

Copy number variations of the extensively amplified Y-linked genes, HSFY and ZNF280BY, in cattle and their association with male reproductive traits in Holstein bulls

Background

Recent transcriptomic analysis of the bovine Y chromosome revealed at least six multi-copy protein coding gene families, including TSPY, HSFY and ZNF280BY, on the male-specific region (MSY). Previous studies indicated that the copy number variations (CNVs) of the human and bovine TSPY were associated with male fertility in men and cattle. However, the relationship between CNVs of the bovine Y-linked HSFY and ZNF280BY gene families and bull fertility has not been investigated.

Results

We investigated the copy number (CN) of the bovine HSFY and ZNF280BY in a total of 460 bulls from 15 breeds using a quantitative PCR approach. We observed CNVs for both gene families within and between cattle breeds. The median copy number (MCN) of HSFY among all bulls was 197, ranging from 21 to 308. The MCN of ZNF280BY was 236, varying from 28 to 380. Furthermore, bulls in the Bos taurus (BTA) lineage had a significantly higher MCN (202) of HSFY than bulls in the Bos indicus (BIN) lineage (178), while taurine bulls had a significantly lower MCN (231) of ZNF280BY than indicine bulls (284). In addition, the CN of ZNF280BY was positively correlated to that of HSFY on the BTAY. Association analysis revealed that the CNVs of both HSFY and ZNF280BY were correlated negatively with testis size, while positively with sire conception rate.

Conclusion

The bovine HSFY and ZNF280BY gene families have extensively expanded on the Y chromosome during evolution. The CN of both gene families varies significantly among individuals and cattle breeds. These variations were associated with testis size and bull fertility in Holstein, suggesting that the CNVs of HSFY and ZNF280BY may serve as valuable makers for male fertility selection in cattle.

Male-specific region of the bovine Y chromosome is gene rich with a high transcriptomic activity in testis development

The male-specific region of the mammalian Y chromosome (MSY) contains clusters of genes essential for male reproduction. The highly repetitive and degenerative nature of the Y chromosome impedes genomic and transcriptomic characterization. Although the Y chromosome sequence is available for the human, chimpanzee, and macaque, little is known about the annotation and transcriptome of nonprimate MSY. Here, we investigated the transcriptome of the MSY in cattle by direct testis cDNA selection and RNA-seq approaches. The bovine MSY differs radically from the primate Y chromosomes with respect to its structure, gene content, and density. Among the 28 protein-coding genes/families identified on the bovine MSY (12 single- and 16 multicopy genes), 16 are bovid specific. The 1,274 genes identified in this study made the bovine MSY gene density the highest in the genome; in comparison, primate MSYs have only 31-78 genes. Our results, along with the highly transcriptional activities observed from these Y-chromosome genes and 375 additional noncoding RNAs, challenge the widely accepted hypothesis that the MSY is gene poor and transcriptionally inert. The bovine MSY genes are predominantly expressed and are differentially regulated during the testicular development. Synonymous substitution rate analyses of the multicopy MSY genes indicated that two major periods of expansion occurred during the Miocene and Pliocene, contributing to the adaptive radiation of bovids. The massive amplification and vigorous transcription suggest that the MSY serves as a genomic niche regulating male reproduction during bovid expansion.

Testis-specific protein Y-encoded copy number is correlated to its expression and the field fertility of Canadian Holstein bulls

Testis-specific protein Y-encoded (TSPY) is present in varying copy number in both human (20-76 copies) and cattle (37-200 copies), and some studies have linked this variation to semen quality in men. The purpose of this study was to determine if TSPY copy number is associated with fertility in bulls by using adjusted non-return rates, a commonly used measure of field fertility in Canada. In addition, we investigated the associations between TSPY copy number and its expression as well as specific semen parameters, such as average sperm concentration, sperm count, ejaculate volume, and motility. In 2 independent trials, TSPY copy number was shown to be positively correlated to adjusted non-return rates (trial #1: Spearman r = 0.34, p < 0.05; trial #2: Spearman r = 0.77, p < 0.01). Furthermore, TSPY copy number was inversely correlated to TSPY mRNA expression in the testis (Pearson r = -0.71, p < 0.0001). There were no correlations of TSPY copy number or expression with the semen parameters measured. Therefore, TSPY copy number might represent a potential marker of bull fertility, but its mechanism does not appear to be directly related to the semen characteristics analyzed as part of this study.

A novel approach to sexing bovine blastocysts using male-specific gene expression

When examining gene expression profiles for the purposes of assessing embryo quality, it is imperative that sex be considered, because many embryonic transcripts have sex-related expression patterns. The objective of this study was to systematically examine eight Y chromosome linked genes (DDX3Y, EIF1AY, HSFY, SRY, TSPY, USP9Y, ZFY, and ZRSR2Y) to characterize their expression in bovine blastocysts and to examine the usefulness of this expression for the purpose of RNA-based embryo sexing. In order to examine the expression of these genes, pools of blastocysts (groups of 10 and 20) as well as single embryos (N = 50) were analyzed with reverse transcriptase polymerase chain reaction (RT-PCR) and reverse transcriptase quantitative PCR (RT-qPCR). Of the 50 single embryos, 32 were concurrently sexed with DNA-based methods. Transcripts of DDX3Y, EIF1AY, TSPY, USP9Y, ZFY and ZRSR2Y were detected in the pooled and single blastocysts, but no transcripts were detected for HSFY or SRY. After performing DNA-based sexing experiments, we concluded that this expression was restricted to the male embryos. The consistency of the expression varied according to the gene as well as the specific primer set. Three genes were expressed in the full set of male embryos, DDX3Y, USP9Y, and ZRSR2Y and therefore represent good candidates for RNA-based sexing methods.

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.

Partial rescue of the KIT-deficient testicular phenotype in KitW-v/KitW-v Tg(TSPY) mice

TSPY encodes the testis-specific protein Y-linked. In man, expression of TSPY is restricted to the testis, where TSPY is expressed in spermatogonia, primary spermatocytes, and round spermatids, and to the prostate gland. There is circumstantial evidence that TSPY is involved in spermatogonial proliferation and gonadal tumorigenesis. Because the laboratory mouse carries the Tspy gene in a naturally silenced state (Tspy-ps), we previously restored TSPY activity in mice and generated a TSPY transgenic mouse line in which the organization and expression of the human TSPY transgene follow the human pattern. In the present study, we generated TSPY transgenic KIT-deficient Kit(W-v)/Kit(W-v) mice and analyzed the histology of the testes and epididymides in order to contribute to understanding TSPY function in early germ cell development and spermatogenesis. The KIT receptor and its ligand KITL, previously called stem cell factor, have an indispensable role in hematopoiesis, melanogenesis, and gametogenesis. Homozygous Kit(W-v) mutant male mice on a C57BL/6J background with a mutation in the Kit gene are infertile due to an almost total loss of germ cells in the testes. In this study, histological analyses of testes and epididymides showed an increased number of meiotic and postmeiotic germ cells in Kit(W-v)/Kit(W-v) Tg(TSPY) mice compared with age-matched Kit(W-v)/Kit(W-v) controls. TSPY was able to restore fertility of some but not all TSPY transgenic Kit(W-v)/Kit(W-v) males. Our findings show that TSPY is able to partially rescue spermatogenesis and fertility of Kit(W-v)/Kit(W-v) mutants and thereby point to a putative role of TSPY in fetal and adult germ cell proliferation.

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.

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.

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

The testis specific protein Y encoded (TSPY) gene is a tandemly repeated gene on the mammalian Y chromosome. It encodes several slightly variant proteins that harbor a conserved domain of approximately 170 amino acids, termed TSPY/SET/NAP1 domain, capable of binding to cyclin B. The human TSPY is preferentially expressed in spermatogonia and to lesser extent in the spermatids. Although rat harbors a single functional Tspy gene on its Y chromosome, the human and rat genes differ in their expression patterns, suggesting that they might serve different or variant functions in the testis. Transcripts of rTspy were first detected in the testis of 28-day-old rats, at which time the first wave of meiotic division was occurring. The rTspy protein was initially detected in stage-9 elongating spermatids and peaked at stage-13 spermatids in adult testis, but not in spermatogonia, unlike the expression pattern of the human TSPY gene. Using a GST pull-down assay, we demonstrated that rTspy could bind to the core histones H2A, H2B, H3, and H4. Rat Tspy co-localized with the histones in the cytoplasm of selected elongated spermatids. Our results suggest that the rTspy may play critical roles as a histone chaperone during maturation of the elongating spermatids in the rat testis.

Characterization of a human TSPY promoter

Human TSPY is a candidate oncogene and is supposed to function as a proliferation factor during spermatogenesis. It is the only mammalian protein-coding gene known to be organized as a tandem repeat gene family. It is expressed at highest level in spermatogonia and to a lower amount in primary spermatocytes. To characterize the human TSPY promoter we used the luciferase reporter system in a mouse spermatogonia derived cell line (GC-1 spg) and in a GC-4 spc cell line, that harbour prophase spermatocytes of the preleptotene and early pachytene stage. We isolated a 1303 bp fragment of the 5'-flanking region of exon 1 that shows significant promoter activity in GC-1 spg and reduced activity in GC-4 spc cells. In order to gain further insight into the organization of the TSPY-promoter, stepwise truncations of the putative promoter sequence were performed. The resulting fragments were cloned into the pGL 3-vector and analysed for reporter gene activity in the murine germ cell lines GC-1 spg and GC-4 spc, leading to the characterization of a core promoter (--159 to--1), an enhancing region (--673 to--364) and a silencing region (--1262 to--669). Database research for cis-active elements yielded two putative SOX-like binding sites in the enhancing region and reporter gene activity was drastically reduced when three nucleotides of the AACAAT SOX core sequence were mutated. Our findings strongly suggest that testis-specific expression of human TSPY is mediated by Sox proteins.

Disrupted sex differentiation and feminization of man and domestic animals

Genital malformations constitute the most common birth defects in man and domestic animals and occur frequently in males since the participation of many genes is required for sex differentiation to proceed in the male direction. The precise dose, timing, and coordination needed for their expression add to the proneness of various stages in male sex differentiation to external influences. The emerging insight, through the identification of genes involved in the sex differentiation cascade, is that over 85% of sex anomalies in human and domestic animal populations are not attributable to chromosome aberrations or to mutations in a known gene. Since a majority of severely malformed individuals are incapable of reproduction, the high rates of these defects have to be results either of new mutations or of collaboration of environmental factors with genes. Increase in specific malformations in domestic animals often indicates increased concentration of liability genes brought together in the conceptus by inbreeding. However, in human populations where inbreeding is not the norm such increases may reflect environment-induced new mutations or interaction of environmental agents with hormone-sensitive genes. This review summarizes the information currently available on the genetics of major events in male sex differentiation and briefly discusses the collaborative role that environment may play in disrupting different components of this process.

TSPY is a cancer testis antigen expressed in human hepatocellular carcinoma

In search for genes associated with hepatocellular carcinoma (HCC) by cDNA microarray, we found that the transcription of TSPY, ‘testis-specific protein Y-encoded’, was upregulated in HCC. Investigation of a broad spectrum of normal and malignant tissues by RT–PCR revealed the TSPY transcript selectively expressed in normal testis, different histological types of human neoplastic tissues, and tumour cell lines. The expression of TSPY in cancer cells was further confirmed by in situ hybridisation. Indirect immunofluorescence microscopy analysis showed that TSPY was localised mainly in the cytoplasm of transiently transfected cells. Testis-specific protein Y-encoded was detected in 50% (16 of 32) of well- and moderately differentiated HCC patients, in 16% (four of 25) of poorly differentiated HCC patients, and in 5% (one of 19) of renal cell cancer patients. A serological survey revealed that 6.6% (seven of 106) HCC patients had anti-TSPY antibody response, demonstrating the immunogenicity of TSPY in humans. In conclusion, these data suggest that TSPY is a novel cancer/testis (CT) antigen and may be a potential candidate in vaccine strategy for immunotherapy in HCC patients.

Differentially expressed nucleolar TGF-beta1 target (DENTT) shows tissue-specific nuclear and cytoplasmic localization and increases TGF-beta1-responsive transcription in primates

Differentially Expressed Nucleolar TGF-beta1 Target (DENTT) is a new member of the TSPY/TSPY-like/SET/NAP-1 (TTSN) superfamily whose mRNA is induced by TGF-beta1 in TGF-beta1-responsive human lung cancer cells. Monkey DENTT mRNA contains a 2085-bp open reading frame that encodes a predicted polypeptide of 695 amino acids with five nuclear localization signals, two coiled-coil regions, and a domain that shows significant identity to a region that defines the TTSN superfamily. RT-PCR amplification and Western blot analyses showed DENTT mRNA and protein in adult monkey tissues, including the adrenal gland, cerebral cortex, and ovary. Immunohistochemical staining showed that numerous neurons were intensely immunoreactive for DENTT, as were anterior pituitary secretory cells, thyroid follicular cells, and smooth muscle cells of arteries and lung bronchial walls. DENTT expression was also prominent in monkey bronchiolar-alveolar adenomas and cell lines. While the addition of TGF-beta1 or retinoic acid to monkey normal lung bronchial 12MBr6 cells and human lung cancer NCI-H727 cells increased DENTT protein production, TGF-beta1 together with retinoic acid resulted in a more sustained increase in DENTT production than with TGF-beta1 or retinoic acid alone. Transient transfection studies showed that ectopic DENTT expression significantly increased TGF-beta1-responsive 3TP-Lux and CAGA12-Lux reporter transcription in 12MBr6 and NCI-H727 cells with TGF-beta1 addition, while ectopic DENTT expression had no significant effect on the transcription of a retinoic acid-responsive element reporter in the presence of retinoic acid or TGF-beta1. These findings suggest new possibilities for DENTT as a TGF-beta1-regulated, but not a retinoic acid-regulated member of the TTSN superfamily in primate physiology.

Organization and concerted evolution of the ampliconic Y-chromosomal TSPY genes from cattle

The Y-chromosomal gene TSPY (testis-specific protein Y-encoded) is probably involved in early spermatogenesis and has a variable copy number in different mammalian species. Analysis of bovine BAC clones leads to an estimate of 90 TSPY loci on the bovine Y chromosome. Half of these loci (TSPY-M1 and TSPY-M2) contain a single copy, while the other loci (TSPY-C) contain a cluster of three, possibly four, truncated pseudogenes. Fluorescence in situ hybridization indicated that the TSPY loci are located mainly on the short arm (Yp). The TSPY genes appear to account for about 2.5% of the Y chromosome and contain several published bovine Y-chromosomal microsatellites. The homology of TSPY and the major Y-chromosomal repetitive elements BRY.2 from cattle and OY.1 from sheep (80-85% similarity) further illustrates how the Y chromosome is shaped by rearrangements and horizontal spreading of the most abundant sequences. A comparison of TSPY-M1 sequences from different BAC clones and from related bovine species suggests concerted evolution as one of the mechanisms of the rapid evolution of the mammalian Y chromosome.

Paternally inherited markers in bovine hybrid populations

The genetic integrity of crossfertile bovine- or cattle-like species may be endangered by species hybridization. Previously, amplified fragment length polymorphism, satellite fragment length polymorphism and microsatellite assays have been used to analyze the species composition of nuclear DNA in taurine cattle, zebu, banteng and bison populations, while mitochondrial DNA reveals the origin of the maternal lineages. Here, we describe species-specific markers of the paternally transmitted Y-chromosome for the direct detection of male-mediated introgression. Convenient PCR-restriction fragment length polymorphism and competitive PCR assays are shown to differentiate the Y-chromosomes of taurine cattle, American bison and European bison, and to detect the banteng origin of Indonesian Madura and Bali cattle bulls.

Generation and characterization of a transgenic mouse with a functional human TSPY

To generate an animal model that is suitable for the analysis of regulation and expression of human testis-specific protein, Y-encoded TSPY, a transgenic mouse line, TgTSPY9, harboring a complete structural human TSPY gene was generated. Fluorescence in situ hybridization and Southern analyses show that approximately 50 copies of the human TSPY transgene are integrated at a single chromosomal site that maps to the distal long arm of the Y chromosome. The transgene is correctly transcribed and spliced according to the human pattern and is mainly expressed in testicular tissue, with spermatogonia and early primary spermatocytes (leptotene and zygotene) as expressing germ cells. TSPY transgenic mice are phenotypically normal, and spermatogenesis is neither impaired nor enhanced by the human transgene. The present study shows that a human TSPY gene integrated into the mouse genome follows the human expression pattern although murine tspy had lost its function in rodent evolution millions of years ago.

Differentially expressed nucleolar TGF-beta1 target (DENTT) in mouse development

Differentially expressed nucleolar TGF-beta1 target (DENTT) is a recently identified gene whose mRNA is differentially affected by TGF-beta1 in TGF-beta1-responsive human lung cancer cells and who is a new member of the TSPY/TSPY-like/SET/NAP-1 (TTSN) protein superfamily. Here, we report that mouse DENTT mRNA contains a 2031-bp open reading frame that encodes a predicted polypeptide of 677-amino acids with a relative molecular mass of 77,671 Da. The mouse and human DENTT sequences show 77% and 78% homology at the nucleotide and amino acid level, respectively. Mouse DENTT is predicted to be a nuclear protein with two nuclear localization signals (NLS), two coiled-coil regions, and a domain that shows significant identity to a region that defines the TTSN superfamily. Green fluorescent protein (GFP)-tagged full-length mouse DENTT transfected into COS-7 cells showed localization predominantly in the nucleolus. Reverse transcription-polymerase chain reaction amplification, Northern hybridization, and Western blot analyses showed expression of mouse DENTT mRNA and protein throughout mouse embryogenesis. Immunohistochemical staining analysis showed that DENTT is expressed in multiple tissues in a defined spatiotemporal pattern during mouse embryogenesis. The heart and primitive brain were the first organs of the embryo that showed immunoreactivity for the DENTT antibody by day 8 of development (E8). In the developing mouse brain, the choroid plexus was intensely stained for DENTT in all stages of development. The spinal cord and dorsal root ganglia were also positive for DENTT staining beginning in the 11-day-old embryo (E11), where homogeneous immunostaining was observed throughout the developing neurons. By day 16 of development (E16), only a small subset of the neuronal population in the spinal cord and dorsal root ganglia was positively stained for DENTT. DENTT immunoreactivity increased steadily with maturation as the differentiation of cartilage and osteoblasts proceeded and reached a maximum in the growth plate during endochondral ossification. DENTT expression was also detected in multiple rodent cell types in vitro, including mouse F9 embryonal carcinoma (EC) cells. Addition of retinoic acid or sodium butyrate to F9 EC cells showed a rapid decrease in expression of DENTT protein occurring by 1 hr that continued to decrease to almost undetectable levels after 24 hr. Cotransfection of full-length mouse DENTT expression plasmid with 3TPLux or COL7A1Luc Luciferase reporter plasmids into F9 EC cells significantly increased the level of 3TPLux reporter transcription while decreasing the level of COL7A1Luc reporter transcription, suggesting that DENTT may play multiple roles in modulating transcriptional responses. These findings suggest new roles for the TTSN superfamily during embryogenesis and differentiation.

Molecular evolution of the murine tspy genes

Molecular aspects of murine evolution were studied by sequencing, and subsequently comparing, introns of the Y-chromosomal tspy genes from Apodemus agrarius, A. sylvaticus, A. flavicollis, Mus platythrix (subgenus Pyromys), M. booduga (subgenus Leggada), and from species of the subgenus Mus, including M. cervicolor, M. macedonicus and M. spretus. Estimates of nucleotide substitution rates in these lineages were in perfect agreement with phylogenetic data previously published by She et al. (1990), Catzeflis et al. (1992; 1993), and Lyon et al. (1996). The only exception was provided by a comparatively late divergence of M. spretus and M. macedonicus. Our data also suggest that M. booduga diverged from the subgenus Mus about 3 Myr ago.

Immortalization of murine male germ cells at a discrete stage of differentiation by a novel directed promoter-based selection strategy

We developed a novel promoter-based selection strategy that could be used to produce cell lines representing sequential stages of spermatogenesis. The method is based on immortalization and subsequent targeted selection by using differentiation-specific promoter regions. As an example for this approach, a new murine germ cell line (GC-4spc) was established using a vector construct that contains the SV40 large T antigen and the neomycin phosphotransferase II gene under the control of the SV40 early promoter and a spermatocyte-specific promoter for human phosphoglycerate kinase 2, respectively. The GC-4spc was characterized as a cell line at the stage between preleptotene and early pachytene spermatocytes. Transcription of three germ cell-specific expressed genes, Pgk2, proacrosin, and the A-myb proto-oncogene, were detected in the GC-4spc cell line using reverse transcription-polymerase chain reaction. Furthermore, TSPY (human testis-specific protein, Y-encoded) and PGK2 (human phosphoglycerate kinase 2) promoter regions showed different transcriptional activities in the GC-4spc cell line compared with the spermatogonia-derived cell line GC-1spg. Thus, our strategy could be used for immortalization of cells at specific stages of differentiation, allowing production of a series of cultured cell lines representing sequential stages of differentiation in given cell lineages.

Organization and expression of rat Tspy

We have isolated both a full-length rat Tspy cDNA from testicular mRNA by rapid amplification of cDNA ends (RACE) and RT-PCR and a full-length rat Tspy gene from genomic DNA by PCR. In contrast to the mouse, where Tspy is present in a single copy and is apparently functionless, and to man and cattle, where TSPY is organized in a moderately repetitive cluster, the rat Tspy locus apparently consists of one complete functional and one truncated, probably nonfunctional, copy, coherently localized on Yp, as revealed by FISH analysis.

A murine TSPY

Sequences homologous to human and bovine TSPY were isolated from M. musculus testicular cDNA, and a nearly full-length gene was polymerase chain reaction (PCR) amplified from mouse genomic DNA. This gene is apparently non-functional. Contrary to the situation encountered in species along the primate and artiodactyl lineages, in which TSPY is moderately repetitive, murine Tspy appears to be single copy. Murine Tspy is located on Yp, i.e. in the same syntenic group as in man. Sequence comparisons of murine, human and bovine TSPY exons suggest that TSPY became non-functional during rodent evolution.

Conserved Y-chromosomal location of TSPY in Bovidae

We determined the chromosomal location of TSPY, the testis-specific protein, Y-encoded, by fluorescence in situ hybridization (FISH) to chromosome spreads of cattle, goat and sheep. Using a cloned polymerase chain reaction (PCR) product of one bovine TSPY family member, we were able to show a conserved Y chromosomal localization for TSPY in all three species. In contrast to a limited regional distribution of TSPY FISH signals on the chromosome of man, other primates, great apes, goat and sheep, in cattle TSPY-related sequences appear to be spread over most of the Y chromosome. The painting effect observed in this species reflects the higher complexity of the bovine TSPY gene family, being composed not only of a tandemly repeated cluster, but harbouring a large number of different family members dispersed all over the Y chromosome.