beta-Microseminoprotein in human spermatozoa and its potential role in male fertility

Sperm traits and seminal plasma proteome of locally adapted hairy rams subjected to intermittent scrotal insulation

The present study evaluated the effects of heat stress on reproductive parameters of hairy rams. Six animals were subjected to scrotal insulation during four consecutive nights (6 PM - 6 AM). Day (D) 0 was the first day of insulation. Scrotal circumference increased from 30.5 ± 0.3 cm (at pre-insulation) to 31.8 ± 0.4 cm on D4, decreased 3.9 cm on D28, returning to 30.6 ± 0.6 cm on D57. Sperm concentration decreased from 3.7 ± 0.12 ×109 sperm/mL before insulation to 2.6 ± 0.1 ×109 on D23, returning to normal on D57. Sperm motility averaged 75 ± 2.9% before insulation, was undetectable on D23, and became normal on D77. Sperm with normal morphology reached 5.9 ± 2.6% on D35 but recovered (86.8 ± 2.1%) on D91. Sperm DNA integrity decreased from 86.5 ± 4.7% before insulation to 11.1 ± 3.7% on D63, returning to pre-insulation values on D120. Sperm BSP immunostaining was reduced after scrotal insulation. Variations in seminal protein abundances coincided with changes in sperm parameters. Seminal plasma superoxide dismutase, carboxypeptidase Q-precursor and NPC intracellular cholesterol transporter 2 decreased on D18, returning to normal after D28. Albumin, inhibitor of carbonic anhydrase precursor, EGF-like repeat and discoid I-like domain-containing protein 3 and polymeric immunoglobulin receptor increased after insulation. In summary, intermittent scrotal insulation drastically altered ram sperm attributes and seminal proteins, especially those associated with oxidative stress. Knowledge of animal´s response to thermal stress is vital in the scenario of climate changes.

The Role of Testosterone in Spermatogenesis: Lessons From Proteome Profiling of Human Spermatozoa in Testosterone Deficiency

Testosterone is essential to maintain qualitative spermatogenesis. Nonetheless, no studies have been yet performed in humans to analyze the testosterone-mediated expression of sperm proteins and their importance in reproduction. Thus, this study aimed to identify sperm protein alterations in male hypogonadism using proteomic profiling. We have performed a comparative proteomic analysis comparing sperm from fertile controls (a pool of 5 normogonadic normozoospermic fertile men) versus sperm from patients with secondary hypogonadism (a pool of 5 oligozoospermic hypogonadic patients due to isolated LH deficiency). Sperm protein composition was analyzed, after peptide labelling with Isobaric Tags, via liquid chromatography followed by tandem mass spectrometry (LC-MS/MS) on an LTQ Velos-Orbitrap mass spectrometer. LC-MS/MS data were analyzed using Proteome Discoverer. Criteria used to accept protein identification included a false discovery rate (FDR) of 1% and at least 1 peptide match per protein. Up to 986 proteins were identified and, of those, 43 proteins were differentially expressed: 32 proteins were under-expressed and 11 were over-expressed in the pool of hypogonadic patients compared to the controls. Bioinformatic analyses were performed using UniProt Knowledgebase, and the Gene Ontology Consortium database based on PANTHER. Notably, 13 of these 43 differentially expressed proteins have been previously reported to be related to sperm function and spermatogenesis. Western blot analyses for A-Kinase Anchoring Protein 3 (AKAP3) and the Prolactin Inducible Protein (PIP) were used to confirm the proteomics data. In summary, a high-resolution mass spectrometry-based proteomic approach was used for the first time to describe alterations of the sperm proteome in secondary male hypogonadism. Some of the differential sperm proteins described in this study, which include Prosaposin, SMOC-1, SERPINA5, SPANXB1, GSG1, ELSPBP1, fibronectin, 5-oxoprolinase, AKAP3, AKAP4, HYDIN, ROPN1B, ß-Microseminoprotein and Protein S100-A8, could represent new targets for the design of infertility treatments due to androgen deficiency.

Three-dimensional structures of avian beta-microseminoproteins: insight from the chicken egg-specific beta-microseminoprotein 3 paralog

Beta‐microseminoproteins (MSMBs) are small disulfide‐rich proteins that are conserved among vertebrates. These proteins exhibit diverse biological activities and were mainly reported to play a role in male fertility, immunity, and embryogenesis. In this work, we focused on the chicken MSMB3 protein that was previously depicted as an egg antibacterial protein. We report that MSMB3 protein is exclusively expressed in the reproductive tissues of laying hens (in contrast to chicken MSMB1 and MSMB2 paralogs), to be incorporated in the egg white during the process of egg formation. We also showed that chicken MSMB3 possesses highly conserved orthologs in bird species, including Neognathae and Palaeognathae. Chicken MSMB3 was purified from egg white using heparin affinity chromatography and was analyzed by top‐down and bottom‐up proteomics. Several proteoforms could be characterized, and a homodimer was further evidenced by NMR spectroscopy. The X‐ray structure of chicken MSMB3 was solved for the first time, revealing that this protein adopts a novel dimeric arrangement. The highly cationic MSMB3 protein exhibits a distinct electrostatic distribution compared with chicken MSMB1 and MSMB2 structural models, and with published mammalian MSMB structures. The specific incorporation of MSMB3 paralog in the egg, and its phylogenetic conservation in birds together with its peculiar homodimer arrangement and physicochemical properties, suggests that the MSMB3 protein has evolved to play a critical role during the embryonic development of avian species. These new data are likely to stimulate research to elucidate the structure/function relationships of MSMB paralogs and orthologs in the animal kingdom.

Sub-fertility in crossbred bulls: deciphering testicular level transcriptomic alterations between zebu (Bos indicus) and crossbred (Bos taurus x Bos indicus) bulls

BACKGROUND

The incidence of poor semen quality and sub-fertility/infertility is higher in crossbred as compared to Zebu males. Several attempts have been made to understand the possible reasons for higher incidence of fertility problems in crossbred males, at sperm phenotype, proteome and genome level but with variable results. Since the quality of the ejaculated spermatozoa is determined by the testicular environment, assessing the testicular transcriptome between these breeds would help in identifying the possible mechanisms associated with infertility in crossbred bulls. However, such information is not available. We performed global transcriptomic profiling of testicular tissue from crossbred and Zebu bulls using Agilent Bos taurus GXP 8X60k AMADID: 29411 array. To the best of our knowledge, this is the first study comparing the testicular mRNAs between crossbred and Zebu bulls.

RESULTS

Out of the 14,419 transcripts detected in bovine testis, 1466 were differentially expressed between crossbred and Zebu bulls, in which 1038 were upregulated and 428 were downregulated in crossbred bulls. PI4KB and DPY19L2 genes, reported to be involved in sperm capacitation and acrosome formation respectively, were among the top 10 downregulated transcripts in crossbred testis. Genes involved in ubiquitination and proteolysis were upregulated, while genes involved in cell proliferation, stem cell differentiation, stem cell population maintenance, steroidogenesis, WNT signalling, protein localization to plasma membrane, endocannabinoid signalling, heparin binding, cAMP metabolism and GABA receptor activity were downregulated in crossbred testis. Among the 10 genes validated using qPCR, expression of CCNYL, SOX2, MSMB, SPATA7, TNP1, TNP2 and CRISP2 followed the same trend as observed in microarray analysis with SPATA7 being significantly downregulated and transition proteins (TNP1, TNP2) being significantly upregulated in crossbred bulls.

CONCLUSIONS

Abundant proteolysis by ubiquitination and downregulation of WNT signaling, cell proliferation, differentiation and steroidogenesis might be associated with higher incidence of poor semen quality and/or sub-fertility/infertility in crossbred bulls as compared to Zebu bulls. Downregulation of SPATA7 (Spermatogenesis Associated 7) and upregulation of transition proteins (TNP1 and TNP2) in crossbred bull testis might be associated with impaired spermatogenesis processes including improper chromatin compaction in crossbred bulls.

The Ubiquitin-Proteasome System Does Not Regulate the Degradation of Porcine β-Microseminoprotein during Sperm Capacitation

Sperm capacitation, one of the key events during successful fertilization, is associated with extensive structural and functional sperm remodeling, beginning with the modification of protein composition within the sperm plasma membrane. The ubiquitin-proteasome system (UPS), a multiprotein complex responsible for protein degradation and turnover, participates in capacitation events. Previous studies showed that capacitation-induced shedding of the seminal plasma proteins such as SPINK2, AQN1, and DQH from the sperm surface is regulated by UPS. Alterations in the sperm surface protein composition also relate to the porcine β-microseminoprotein (MSMB/PSP94), seminal plasma protein known as immunoglobulin-binding factor, and motility inhibitor. MSMB was detected in the acrosomal region as well as the flagellum of ejaculated boar spermatozoa, while the signal disappeared from the acrosomal region after in vitro capacitation (IVC). The involvement of UPS in the MSMB degradation during sperm IVC was studied using proteasomal interference and ubiquitin-activating enzyme (E1) inhibiting conditions by image-based flow cytometry and Western blot detection. Our results showed no accumulation of porcine MSMB either under proteasomal inhibition or under E1 inhibiting conditions. In addition, the immunoprecipitation study did not detect any ubiquitination of sperm MSMB nor was MSMB detected in the affinity-purified fraction containing ubiquitinated sperm proteins. Based on our results, we conclude that UPS does not appear to be the regulatory mechanism in the case of MSMB and opening new questions for further studies. Thus, the capacitation-induced processing of seminal plasma proteins on the sperm surface may be more complex than previously thought, employing multiple proteolytic systems in a non-redundant manner.

Quantitative Analysis of the Seminal Plasma Proteome in Secondary Hypogonadism

In the grey zone of testosterone levels between 8 and 12 nmol/L, the usefulness of therapy is controversial; as such, markers of tissue action of androgens may be helpful in adjusting clinical decisions. To better understand the effect of the hypothalamic-pituitary-testicular axis on male accessory secretion, we performed a proteomic quantitative analysis of seminal plasma in patients with secondary hypogonadism, before and after testosterone replacement therapy (TRT). Ten male patients with postsurgical hypogonadotrophic hypogonadism were enrolled in this study, and five of these patients were evaluated after testosterone treatment. Ten men with proven fertility were selected as a control group. An aliquot of seminal plasma from each individual was subjected to an in-solution digestion protocol and analyzed using an Ultimate 3000 RSLC-nano HPLC apparatus coupled to a LTQ Orbitrap Elite mass spectrometer. The label-free quantitative analysis was performed via Precursor Ions Area Detector Node. Eleven proteins were identified as decreased in hypogonadic patients versus controls, which are primarily included in hydrolase activity and protein binding activity. The comparison of the proteome before and after TRT comes about within the discovery of six increased proteins. This is the primary application of quantitative proteomics pointed to uncover a cluster of proteins reflecting an impairment not only of spermatogenesis but of the epididymal and prostate epithelial cell secretory function in male hypogonadism. The identified proteins might represent putative clinical markers valuable within the follow-up of patients with distinctive grades of male hypogonadism.

Prostate-specific markers to identify rare prostate cancer cells in liquid biopsies

Despite improvements in early detection and advances in treatment, patients with prostate cancer continue to die from their disease. Minimal residual disease after primary definitive treatment can lead to relapse and distant metastases, and increasing evidence suggests that circulating tumour cells (CTCs) and bone marrow-derived disseminated tumour cells (BM-DTCs) can offer clinically relevant biological insights into prostate cancer dissemination and metastasis. Using epithelial markers to accurately detect CTCs and BM-DTCs is associated with difficulties, and prostate-specific markers are needed for the detection of these cells using rare cell assays. Putative prostate-specific markers have been identified, and an optimized strategy for staining rare cancer cells from liquid biopsies using these markers is required. The ideal prostate-specific marker will be expressed on every CTC or BM-DTC throughout disease progression (giving high sensitivity) and will not be expressed on non-prostate-cancer cells in the sample (giving high specificity). Some markers might not be specific enough to the prostate to be used as individual markers of prostate cancer cells, whereas others could be truly prostate-specific and would make ideal markers for use in rare cell assays. The goal of future studies is to use sensitive and specific prostate markers to consistently and reliably identify rare cancer cells.

Loss of PSP94 expression is associated with early PSA recurrence and deteriorates outcome of PTEN deleted prostate cancers

Objective

Prostate secretory protein of 94 amino acids (PSP94) is a target gene of the EZH2 transcriptional repressor and is often downregulated in prostate cancer; however, its prognostic value is disputed.

Methods

Immunohistochemical analysis of a tissue microarray of 12, 432 prostate cancer specimens was performed to evaluate PSP94 expression. Correlation of PSP94 expression with tumor phenotype, patient prognosis, TMPRSS2:ERG fusion status, EZH2 expression and PTEN deletion was studied.

Results

PSP94 expression was increased in benign prostatic hyperplasia; however, it was downregulated in 48% and negative in 42% of the 9, 881 interpretable prostate cancer specimens. The loss of PSP94 expression was inversely correlated to EZH2 expression (P < 0.0001) and largely unrelated to the ERG status, but strongly correlated with high Gleason grade, advanced tumor stage, and nodal metastasis ( P <0.0001 each). The fraction of PSP94-negative cancer specimens increased from 40% in pT2 to 52% in pT3b-pT4 ( P < 0.0001) and from 40% in Gleason 3+3 = 6 to 46% in Gleason 4+3 = 7 and 60% in Gleason ≥4+4 = 8 ( P < 0.0001). Loss of PSP94 was linked to early prostate-specific antigen recurrence, but with little absolute effect ( P < 0.0001). However, it provided additional prognostic impact in cancer specimens with PTEN deletion. Loss of PSP94 deteriorated prognosis of cancer patients with PTEN deletion by more than 10% (P < 0.0001). The combination of PTEN deletion and PSP94 loss provided independent prognostic information that was observed in several subgroups defined by classical and quantitative Gleason grade.

Conclusions

The results of our study suggest that combined PSP94/PTEN analysis can be potentially used in the clinical prognosis of prostate cancer.

STAT6, PBX2, and PBRM1 Emerge as Predicted Regulators of 452 Differentially Expressed Genes Associated With Puberty in Brahman Heifers

The liver plays a central role in metabolism and produces important hormones. Hepatic estrogen receptors and the release of insulin-like growth factor 1 (IGF1) are critical links between liver function and the reproductive system. However, the role of liver in pubertal development is not fully understood. To explore this question, we applied transcriptomic analyses to liver samples of pre- and post-pubertal Brahman heifers and identified differentially expressed (DE) genes and genes encoding transcription factors (TFs). Differential expression of genes suggests potential biological mechanisms and pathways linking liver function to puberty. The analyses identified 452 DE genes and 82 TF with significant contribution to differential gene expression by using a regulatory impact factor metric. Brain-derived neurotrophic factor was observed as the most down-regulated gene (P = 0.003) in post-pubertal heifers and we propose this gene influences pubertal development in Brahman heifers. Additionally, co-expression network analysis provided evidence for three TF as key regulators of liver function during pubertal development: the signal transducer and activator of transcription 6, PBX homeobox 2, and polybromo 1. Pathway enrichment analysis identified transforming growth factor-beta and Wnt signaling pathways as significant annotation terms for the list of DE genes and TF in the co-expression network. Molecular information regarding genes and pathways described in this work are important to further our understanding of puberty onset in Brahman heifers.

Vasectomy and Prostate Cancer Risk in the European Prospective Investigation Into Cancer and Nutrition (EPIC)

Purpose Vasectomy is a commonly used form of male sterilization, and some studies have suggested that it may be associated with an increased risk of prostate cancer, including more aggressive forms of the disease. We investigated the prospective association of vasectomy with prostate cancer in a large European cohort, with a focus on high-grade and advanced-stage tumors, and death due to prostate cancer. Patients and Methods A total of 84,753 men from the European Prospective Investigation into Cancer and Nutrition (EPIC), aged 35 to 79 years, provided information on vasectomy status (15% with vasectomy) at recruitment and were followed for incidence of prostate cancer and death. We estimated the association of vasectomy with prostate cancer risk overall, by tumor subtype, and for death due to prostate cancer, using multivariable-adjusted Cox proportional hazards models. Results During an average follow-up of 15.4 years, 4,377 men were diagnosed with prostate cancer, including 641 who had undergone a vasectomy. Vasectomy was not associated with prostate cancer risk (hazard ratio [HR], 1.05; 95% CI, 0.96 to 1.15), and no evidence for heterogeneity in the association was observed by stage of disease or years since vasectomy. There was some evidence of heterogeneity by tumor grade ( P = .02), with an increased risk for low-intermediate grade (HR, 1.14; 95% CI, 1.01 to 1.29) but not high-grade prostate cancer (HR, 0.83; 95% CI, 0.64 to 1.07). Vasectomy was not associated with death due to prostate cancer (HR, 0.88; 95% CI, 0.68 to 1.12). Conclusion These findings from a large European prospective study show no elevated risk for overall, high-grade or advanced-stage prostate cancer, or death due to prostate cancer in men who have undergone a vasectomy compared with men who have not.

Identification of CRISP2 from human sperm as PSP94-binding protein and generation of CRISP2-specific anti-peptide antibodies

Cysteine-rich secretory proteins (CRISPs) are mainly found in the mammalian male reproductive tract and reported to be involved at different stages of fertilization. CRISPs have been shown to interact with prostate secretory protein of 94 amino acids (PSP94) from diverse sources, and the binding of these evolutionarily conserved proteins across species is proposed to be of functional significance. Of the three mammalian CRISPs, PSP94-CRISP3 interaction is well characterized, and specific binding sites have been identified; whereas, CRISP2 has been shown to interact with PSP94 in vitro. Interestingly, human CRISP3 and CRISP2 proteins are closely related showing 71.4% identity. In this study, we identified CRISP2 as a potential binding protein of PSP94 from human sperm. Further, we generated antisera capable of specifically detecting CRISP2 and not CRISP3. In this direction, specific peptides corresponding to the least conserved ion channel regulatory region were synthesized, and polyclonal antibodies were generated against the peptide in rabbits. The binding characteristics of the anti-CRISP2 peptide antibody were evaluated using competitive ELISA. Immunoblotting experiments also confirmed that the peptide was able to generate antibodies capable of detecting the mature CRISP2 protein present in human sperm lysate. Furthermore, this anti-CRISP2 peptide antibody also detected the presence of native CRISP2 on sperm.Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

Target antigens for Hs-14 monoclonal antibody and their various expression in normozoospermic and asthenozoospermic men

Background

Poor semen quality is one of the main causes of infertility. We have generated a set of monoclonal antibodies to human sperm and used them to investigate sperm quality. Some of these antibodies found differences in the expression of proteins between normal sperm and pathological sperm displaying severe defects. One of them was the Hs-14 antibody.

The aim of this paper was to determine the target protein of the Hs-14 monoclonal antibody and to investigate the expression of the Hs-14-reacting protein on the sperm of asthenozoospermic men with sperm motility defect and of healthy normozoospermic men.

Methods

Indirect immunofluorescence, one-dimensional and two-dimensional polyacrylamide gel electrophoresis, immunoblotting and mass spectrometry.

Results

The Hs-14 antibody binds fibronectin, β-tubulin and valosin-containing protein - new name for this protein is transitional endoplasmic reticulum ATPase (TERA). Since the Hs-14 reaction with TERA remained the strongest at the highest antibody dilution, and Hs-14 consistently labelled the same spot or band as the monospecific anti-TERA antibody on immunoblots, we assume that TERA is an Hs-14-specific protein. Binding of fibronectin and β-tubulin might represent nonspecific cross-reactivity or Hs-14 reaction with similar epitopes of these proteins.

A significant difference (P < 0.001) in immunofluorescence staining with Hs-14 was found between the normozoospermic and asthenozoospermic men.

Conclusion

The Hs-14 antibody enables discrimination between sterile or subfertile asthenozoospermic and fertile normozoospermic men. Decreased levels of TERA in men can be used as a biomarker of reduced fertility.

Electronic supplementary material

The online version of this article (doi:10.1186/s12610-015-0025-0) contains supplementary material, which is available to authorized users.

Transcriptomic Analysis of Ovaries from Pigs with High And Low Litter Size

Litter size is one of the most important economic traits for pig production as it is directly related to the production efficiency. Litter size is affected by interactions between multiple genes and the environment. While recent studies have identified some genes associated with prolificacy in pigs, transcriptomic studies of specific genes affecting litter size in porcine ovaries are rare. In order to identify candidate genes associated with litter size in swine, we assessed gene expression differences between the ovaries of Yorkshire pigs with extremely high and low litter sizes using the RNA-Seq method. A total of 1 243 differentially expressed genes were identified: 897 genes were upregulated and 346 genes were downregulated in high litter size ovary samples compared with low litter size ovary samples. A large number of these genes related to steroid hormone regulation in animal ovaries, including 59 Gene Ontology terms and 27 Kyoto Encyclopedia of Genes and Genomes pathways involved in steroid biosynthesis and ovarian steroidogenesis. From these differentially expressed genes, we identified a total of 11 genes using a bioinformatics screen that may be associated with high litter size in Yorkshire pigs. These results provide a list of new candidate genes for porcine litter size and prolificacy to be further investigated.

MSMB variation and prostate cancer risk: clues towards a possible fungal etiology

BACKGROUND. With recent advances in high-throughput sequencing technologies, many prostate cancer risk loci have been identified, including rs10993994, a single nucleotide polymorphism (SNP) located near the MSMB gene. Variant allele (T) carriers of this SNP produce less prostate secretory protein 94 (PSP94), the protein product of MSMB, and have an increased risk of prostate cancer (approximately 25% per T allele), suggesting that PSP94 plays a protective role in prostate carcinogenesis, although the mechanisms for such protection are unclear. METHODS. We reviewed the literature on possible mechanisms for PSP94 protection for prostate cancer. RESULTS. One possible mechanism is tumor suppression, as PSP94 has been observed to inhibit cell or tumor growth in in vitro and in vivo models. Another novel mechanism, which we propose in this review article, is that PSP94 may protect against prostate cancer by preventing or limiting an intracellular fungal infection in the prostate. This mechanism is based on the recent discovery of PSP94's fungicidal activity in low-calcium environments (such as the cytosol of epithelial cells), and accumulating evidence suggesting a role for inflammation in prostate carcinogenesis. We provide further details of our proposed mechanism in this review article. CONCLUSIONS. To explore this mechanism, future studies should consider screening prostate specimens for fungi using the rapidly expanding number of molecular techniques capable of identifying infectious agents from the entire tree of life.

Role of β-microseminoprotein from prostate cancer initiation to recurrence: A mini-review

Medline/Pubmed articles relevant to this topic were considered using the search terms β-microseminoprotein, MSMB, prostate secretory protein of 94 amino acids and PSP94. Full articles were retrieved when the abstract was considered relevant. In addition, other data related to this topic including our own are discussed. Summary of findings-β-microseminoprotein (MSMB) is increasingly being considered as a marker for prostate cancer, as reduced levels have been associated with the disease. Here we review various aspects of this protein including its biological and physiological variants, binding proteins and immune modulation; its importance as a marker for biochemical recurrence of prostate cancer; prostate cancer related splice variants and its therapeutic utility. Two of the most important properties of MSMB are related to anticancer functions and immune modulation. Predominant expression of two (short and full-length) splice variants of MSMB has been observed from normal prostate and several other tissues. In benign prostate hyperplasia the short isoform is dominant, constituting 98% of this isoform, whereas in prostate cancer 96% constitute the full-length isoform. The MSMB promoter single nucleotide polymorphism rs10993994 with the C allele functions as an activated cyclic adenosine monophosphate response element binding protein binding site. This C variant of rs10993994 could be responsible for the production of splice variants under variable conditions. MSMB has binding motifs to a few known proteins including immunoglobulin G and several Cysteine-rich secretory proteins family proteins. MSMB bound to these proteins is considered as immune modulating. Use of MSMB as a urinary marker for detecting aggressive prostate cancers that could resist radiation and surgical treatments, seems possible, but needs further investigation. The ratio of MSMB splice variants could also be a possible approach in understanding prostate cancers, with higher ratios indicating severe disease.

Association of prostate cancer susceptibility variant (MSMB) rs10993994 with risk of spermatogenic failure

β-Microseminoprotein (MSMB) is one of the most abundant proteins in human seminal plasma. It has been identified that MSMB increased significantly in oligoasthenoteratozoospermic patients compared with fertile controls. We hypothesized that the functional polymorphism (rs10993994) of MSMB gene could be a risk factor for spermatogenic failure. For this study, 338 patients with idiopathic oligozoospermia or azoospermia and 382 fertile controls were recruited from an infertility clinic. Semen analysis was performed by computer-assisted semen analysis system. The functional polymorphism of MSMB gene was genotyped using TaqMan method. Sixty three seminal plasma samples were used to test the expression of MSMB by enzyme-linked immunosorbent assay (ELISA). The TT genotype and T allele were associated with an increased risk of idiopathic infertility with azoospermia (TT genotype: OR, 1.75; 95% CI, 1.03-2.95; T allele: OR, 1.34; 95% CI, 1.03-1.75). However, no differences were found in risk for the TT genotype or T allele among men with oligozoospermia. In addition, idiopathic infertile males have significantly higher MSMB expression levels than fertile controls. We present the first epidemiologic evidence supporting the involvement of common genetic polymorphism in MSMB gene in spermatogenic failure. These results suggest that men carrying the variant have an increased risk of spermatogenic failure associated with male infertility. Further studies are needed to confirm the roles of the polymorphism in idiopathic azoospermia and investigate the biological mechanism of elevated MSMB expression in infertile males.

Prostate Secretory Protein of 94 amino acids (PSP94) binds to prostatic acid phosphatase (PAP) in human seminal plasma

Prostate Secretory Protein of 94 amino acids (PSP94) is one of the major proteins present in the human seminal plasma. Though several functions have been predicted for this protein, its exact role either in sperm function or in prostate pathophysiology has not been clearly defined. Attempts to understand the mechanism of action of PSP94 has led to the search for its probable binding partners. This has resulted in the identification of PSP94 binding proteins in plasma and seminal plasma from human. During the chromatographic separation step of proteins from human seminal plasma by reversed phase HPLC, we had observed that in addition to the main fraction of PSP94, other fractions containing higher molecular weight proteins also showed the presence of detectable amounts of PSP94. This prompted us to hypothesize that PSP94 could be present in the seminal plasma complexed with other protein/s of higher molecular weight. One such fraction containing a major protein of ~47 kDa, on characterization by mass spectrometric analysis, was identified to be Prostatic Acid Phosphatase (PAP). The ability of PAP present in this fraction to bind to PSP94 was demonstrated by affinity chromatography. Co-immunoprecipitation experiments confirmed the presence of PSP94-PAP complex both in the fraction studied and in the fresh seminal plasma. In silico molecular modeling of the PSP94-PAP complex suggests that β-strands 1 and 6 of PSP94 appear to interact with domain 2 of PAP, while β-strands 7 and 10 with domain 1 of PAP. This is the first report which suggests that PSP94 can bind to PAP and the PAP-bound PSP94 is present in human seminal plasma.

Mapping of the binding sites involved in PSP94-CRISP-3 interaction by molecular dissection of the complex

BACKGROUND

Human Prostate Secretory Protein of 94 amino acids (PSP94) has been shown to bind human CRISP-3 (cysteine-rich secretory protein 3) with very high affinity. CRISP-3 belongs to the CRISP family of proteins having a PR-1 (pathogenesis related protein 1) domain at its N-terminal and ion channel regulatory (ICR) domain at its C-terminal connected by a hinge region. Functional significance of this complex is not yet known.

METHODS

In order to identify the residues and/or regions involved in PSP94-CRISP-3 interaction, site-directed mutagenesis was employed. Effect of the mutations on the interaction was studied by co-immunoprecipitation (Co-IP).

RESULTS

For PSP94, amino acids Y(3), F(4), P(56) and the C-terminal β-strand were found to be crucial for interacting with CRISP-3. A disulfide bond between the two domains of PSP94 (C(37)A-C(73)A) was also important for this interaction. In case of CRISP-3, the N-terminal domain alone could not maintain a strong interaction with PSP94 but it required presence of the hinge region and not the C-terminal domain. Apart from CRISP-3, CRISP-2 was also found to interact with human PSP94. Based on our findings the most likely model of PSP94-CRISP-3 complex has been proposed.

CONCLUSION

The terminal β-strands of PSP94 contact the first α-helix and the hinge region of CRISP-3.

GENERAL SIGNIFICANCE

Involvement of the hinge region of CRISPs in interaction with PSP94 may affect the domain movement of CRISPs essential for the ion-channel regulatory activity resulting in inhibition of this activity.

A novel MSMB-related microprotein in the postovulatory egg coats of marsupials

BACKGROUND

Early marsupial conceptuses differ markedly from those of eutherian mammals, especially during cleavage and early blastocyst stages of development. Additionally, in marsupials the zona pellucida is surrounded by two acellular layers, the mucoid coat and shell, which are formed from secretions from the reproductive tract.

RESULTS

We report the identification of a novel postovulatory coat component in marsupials, which we call uterinesecreted microprotein (USM). USM belongs to a family of disulfide-rich microproteins of unconfirmed function that is found throughout deuterostomes and in some protostomes, and includes β-microseminoprotein (MSMB) and prostate-associated microseminoprotein (MSMP). We describe the evolution of this family in detail, including USM-related sequences in other vertebrates. The orthologue of USM in the tammar wallaby, USM1, is expressed by the endometrium with a dynamic temporal profile, possibly under the control of progesterone.

CONCLUSIONS

USM appears to have evolved in a mammalian ancestor specifically as a component of the postovulatory coats. By analogy with the known properties of MSMB, it may have roles in regulating sperm motility/survival or in the immune system. However, its C-terminal domain is greatly truncated compared with MSMB, suggesting a divergent function.

Reproductive tissue expression and sperm localization of porcine beta-microseminoprotein

Beta-microseminoprotein (MSP) is a predominant protein of human seminal plasma and originates from prostate secretions. MSP from boar seminal plasma has been sequenced and shows only 50%-52% homology with that of human. Porcine MSP is synthesized by the post-natal prostate gland and is identical with the sperm motility inhibitor. Although MSP is a protein characteristic of the prostate gland, we have established the presence of its mRNA transcript not only in boar prostate but also in other reproductive organ tissues. In extracts of all these organs, specific polyclonal antiMSP antibody recognizes a 12-kDa protein band identified by mass spectrometry as MSP. Immunofluorescence (IMF) has revealed the occurrence of MSP in the epithelial tissue of the prostate, epididymis, seminal vesicles and Cowper's glands. MSP has been localized on epididymal spermatozoa in the acrosomal region and on the flagellum of ejaculated spermatozoa. The absence of MSP on the surface of capacitated spermatozoa together with the antibody detection of MSP in the sperm acidic extract after in vitro capacitation indicates its acrosomal origin. Additionally, MSP has been localized by IMF in the sperm acrosome in capacitated spermatozoa with a permeabilized plasma membrane and by electron microscopy in ejaculated spermatozoa. The function of MSP in seminal plasma and spermatozoa is not fully understood. Nevertheless, the secretion of porcine MSP by various reproductive organs indicates its multiple roles in the reproductive process. For the first time in mammalian species, MSP has been localized in various physiological stages of sperm.

Context-dependent effects of genome-wide association study genotypes and macroenvironment on time to biochemical (prostate specific antigen) failure after prostatectomy

BACKGROUND

Disparities in cancer defined by race, age, or gender are well established. However, demographic metrics are surrogates for the complex contributions of genotypes, exposures, health care, socioeconomic and sociocultural environment, and many other factors. Macroenvironmental factors represent novel surrogates for exposures, lifestyle, and other factors that are difficult to measure but might influence cancer outcomes.

METHODS

We applied a "multilevel molecular epidemiology" approach using a prospective cohort of 444 White prostate cancer cases who underwent prostatectomy and were followed until biochemical failure (BF) or censoring without BF. We applied Cox regression models to test for joint effects of 86 genome-wide association study-identified genotypes and macroenvironment contextual effects after geocoding all cases to their residential census tracts. All analyses were adjusted for age at diagnosis and tumor aggressiveness.

RESULTS

Residents living in census tracts with a high proportion of older single heads of household, high rates of vacant housing, or high unemployment had shorter time until BF postsurgery after adjustment for patient age and tumor aggressiveness. After correction for multiple testing, genotypes alone did not predict time to BF, but interactions predicting time to BF were observed for MSMB (rs10993994) and percentage of older single heads of households (P = 0.0004), and for HNF1B/TCF2 (rs4430796) and census tract per capita income (P = 0.0002).

CONCLUSIONS

The context-specific macroenvironmental effects of genotype might improve the ability to identify groups that might experience poor prostate cancer outcomes.

IMPACT

Risk estimation and clinical translation of genotype information might require an understanding of both individual- and macroenvironment-level context.

A common prostate cancer risk variant 5' of microseminoprotein-beta (MSMB) is a strong predictor of circulating beta-microseminoprotein (MSP) levels in multiple populations

BACKGROUND

β-Microseminoprotein (MSP) is one of the three most abundantly secreted proteins of the prostate and has been suggested as a biomarker for prostate cancer risk. A common variant, rs10993994, in the 5' region of the gene that encodes MSP (MSMB) has recently been identified as a risk factor for prostate cancer.

METHODS

We examined the association between rs10993994 genotype and MSP levels in a sample of 500 prostate cancer-free men from four racial/ethnic populations in the Multiethnic Cohort (European Americans, African Americans, Latinos, and Japanese Americans). Generalized linear models were used to estimate the association between rs10993994 genotype and MSP levels.

RESULTS

We observed robust associations between rs10994994 genotype and MSP levels in each racial/ethnic population (all P < 10(-8)), with carriers of the C allele having lower geometric mean MSP levels (ng/mL; CC/CT/TT genotypes: European Americans, 28.8/20.9/10.0; African Americans, 29.0/21.9/10.9; Latinos, 29.2/17.1/8.3; and Japanese Americans, 25.8/16.4/6.7). We estimated the variant accounts for 30% to 50% of the variation in MSP levels in each population. We also observed significant differences in MSP levels between populations (P = 3.5 × 10(-6)), with MSP levels observed to be highest in African Americans and lowest in Japanese Americans.

CONCLUSIONS

Rs10993994 genotype is strongly associated with plasma MSP levels in multiple racial/ethnic populations.

IMPACT

This supports the hypothesis that rs10993994 may be the biologically functional allele.

Array-CGH analysis in patients with syndromic and non-syndromic XY gonadal dysgenesis: evaluation of array CGH as diagnostic tool and search for new candidate loci

BACKGROUND

XY gonadal dysgenesis (XY-GD) is a heterogeneous disorder characterized by failure of testicular development despite a normal male karyotype. Non-syndromic and syndromic forms can be delineated. Currently, only a minority of cases can be explained by gene mutations.

METHODS

The aim of this study was to detect microdeletions and duplications by using high-resolution Agilent oligonucleotide arrays in a cohort of 87 patients with syndromic or non-syndromic 46,XY-GD.

RESULTS

In 26 patients, we identified gains or losses in regions including genes involved in XY-GD (DMRT1, SOX9, DAX1) or in regions, which have not been described as polymorphic copy number variants (CNVs).

CONCLUSIONS

This study shows that array comparative genomic hybridization (CGH) analysis is a useful tool for the molecular diagnosis of XY-GD as well as for the identification of potential candidate genes involved in male sexual development.

High-affinity binding of seminal plasma PSP94 to human immunoglobulin is through the Fab domain

Prostate secretory protein of 94 amino acids (PSP94) is one of the major proteins present in human seminal plasma. We had earlier reported that PSP94 has the ability to bind to human IgG. The aims of the present study were to further delineate the PSP94-IgG interaction and to understand whether this could have any significance in sperm function. Direct binding of IgG fragments to PSP94 showed maximal binding with F(ab')(2) followed by Fab, while Fc displayed least binding in ELISA. Binding kinetics of PSP94-IgG interaction using surface plasmon resonance (SPR) revealed high-affinity binding of IgG to PSP94 with a dissociation constant (K(D)) of 8.8 x 10(-)(11)M. PSP94-IgG interaction was found to be through the Fab domains of IgG. Real-time interaction kinetics revealed association constants for binding of IgG, Fab, and F(ab')(2) towards PSP94 to be of the same order but with altered dissociation constants. IgG and its F(ab')(2) fragment once complexed to PSP94 demonstrated negligible dissociation, while dissociation rate of Fab fragment was 6.6 x 10(-)(4). In silico molecular modeling of PSP94-IgG complex identified N- and C-terminal beta-strands of PSP94 to be the most plausible region involved in IgG interaction. Immunofluorescence studies revealed that IgG bound to human spermatozoa predominantly in the tail region, which could be prevented when IgG was preincubated with PSP94. This study reports for the first time that IgG forms a high-affinity complex with PSP94 through its F(ab')(2) domain and reveals the ability of PSP94 to prevent binding of IgG to spermatozoa.

Crystal structure of prostate secretory protein PSP94 shows an edge-to-edge association of two monomers to form a homodimer

Several recent genome-wide association studies have linked the human MSMB gene, encoding prostate secretory protein of 94 residues (PSP94), with prostate cancer susceptibility. PSP94 is one of the most abundant proteins from prostatic secretions and a primary constituent of human semen. PSP94 suppresses tumor growth and metastasis, and its expression gradually decreases during progression of the prostate cancer. It is a rapidly evolving protein with homologues present in several species with 10 conserved cysteine residues. PSP94 homologues show high-affinity binding with different proteins from the cysteine-rich secretory protein family, some of which have been shown to be ion channel blockers. Here, we report the crystal structure of human PSP94 at 2.3 A resolution. The structure shows that the amino and the carboxyl ends of the polypeptide chain are held in close proximity facing each other. A strong hydrogen bond between these ends, which are located respectively on the first and the last beta-strands, leads to formation of an almost straight edge in PSP94 structure. Crystal structure shows that these edges from two PSP94 monomers associate in antiparallel fashion, leading to formation of a dimer. Our studies further show that dimers dissociate into monomers at acidic pH, possibly through distortion of the straight edge. Further, based on several observations, we propose that PSP94 binds to cysteine-rich secretory proteins and immunoglobulin G through the same edge, which is involved in the formation of PSP94 dimeric interface.

The potential value of microseminoprotein-beta as a prostate cancer biomarker and therapeutic target

BACKGROUND

Recent genome-wide association studies have shown an association of a SNP two base pairs upstream of the 5' UTR of the microseminoprotein-beta (MSMB) gene with an increased risk of developing the prostate cancer, re-igniting interest in its protein product, MSMB.

METHODS

As one of the most abundant prostatic proteins, MSMB can be reliably detected in tissue and serum.

RESULTS

It has been consistently shown that MSMB expression is high in normal and benign prostate tissue and lowered or lost in prostate cancer suggesting that it might be a useful tissue biomarker for prostate cancer diagnosis and its levels in serum may be useful as a marker for prognosis. Members of the cysteine-rich secretory protein family and laminin receptors have been shown to bind MSMB at the cell surface and in serum thereby regulating apoptosis. Thus, in the benign prostate, MSMB regulates cell growth, but when MSMB is lost during tumourigenesis, cells are able to grow in a more uncontrolled manner. Both full length MSMB and a short peptide comprised of amino acids 31-45 have been tested for potential therapeutic benefit in mouse models and humans.

CONCLUSIONS

MSMB has potential as a biomarker of prostate cancer development, progression and recurrence and potentially as a target for therapeutic intervention.

Purification and preliminary X-ray crystallographic studies of beta-microseminoprotein from human seminal plasma

beta-Microseminoprotein (beta-MSP) is a small cysteine-rich protein with a molecular mass of 10 kDa. It was first isolated from human seminal plasma and has subsequently been identified from several species. Comparison of the amino-acid sequences of beta-MSP proteins suggests that the protein is a rapidly evolving protein. The function of beta-MSP is poorly understood. Furthermore, no crystal structure has been reported of any beta-MSP; therefore, determination of the crystal structure of beta-MSP is the foremost task in order to understand the function of this protein completely. Here, the purification, crystallization and preliminary X-ray diffraction analysis of beta-MSP from human seminal plasma are described. The protein was purified using anion-exchange and size-exclusion chromatography and the purified protein was crystallized using 0.1 M ammonium sulfate, 0.1 M HEPES buffer pH 7.0 and 20%(w/v) PEG 3350. The crystals belonged to the tetragonal space group P4(3)22 and contained three beta-MSP molecules in the asymmetric unit. X-ray intensity data were collected to 2.4 A resolution.

Crystallization and preliminary X-ray diffraction analysis of human seminal plasma protein PSP94

The human seminal plasma protein PSP94 is a small protein of 94 residues that contains ten cysteines. Since its discovery about 25 years ago, several potential biological functions have been reported for this protein. Many PSP94 homologues have also been identified since then from various species, but no crystal structure has been determined to date. PSP94 has been purified from human seminal plasma and crystallized. These crystals diffracted to approximately 2.3 A resolution and belonged to space group P4(1)2(1)2, with unit-cell parameters a = 107.9, b = 107.9, c = 92.1 A. There are four molecules in the asymmetric unit. Structure solution by the heavy-atom method is currently in progress.

The CAP superfamily: cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins--roles in reproduction, cancer, and immune defense

The cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins (CAP) superfamily members are found in a remarkable range of organisms spanning each of the animal kingdoms. Within humans and mice, there are 31 and 33 individual family members, respectively, and although many are poorly characterized, the majority show a notable expression bias to the reproductive tract and immune tissues or are deregulated in cancers. CAP superfamily proteins are most often secreted and have an extracellular endocrine or paracrine function and are involved in processes including the regulation of extracellular matrix and branching morphogenesis, potentially as either proteases or protease inhibitors; in ion channel regulation in fertility; as tumor suppressor or prooncogenic genes in tissues including the prostate; and in cell-cell adhesion during fertilization. This review describes mammalian CAP superfamily gene expression profiles, phylogenetic relationships, protein structural properties, and biological functions, and it draws into focus their potential role in health and disease. The nine subfamilies of the mammalian CAP superfamily include: the human glioma pathogenesis-related 1 (GLIPR1), Golgi associated pathogenesis related-1 (GAPR1) proteins, peptidase inhibitor 15 (PI15), peptidase inhibitor 16 (PI16), cysteine-rich secretory proteins (CRISPs), CRISP LCCL domain containing 1 (CRISPLD1), CRISP LCCL domain containing 2 (CRISPLD2), mannose receptor like and the R3H domain containing like proteins. We conclude that overall protein structural conservation within the CAP superfamily results in fundamentally similar functions for the CAP domain in all members, yet the diversity outside of this core region dramatically alters target specificity and, therefore, the biological consequences.