The human cysteine-rich secretory protein (CRISP) family. Primary structure and tissue distribution of CRISP-1, CRISP-2 and CRISP-3

Semen Protein CRISP3 Promotes Reproductive Performance of Boars through Immunomodulation

Semen proteins play an important role in male reproductive performance and sperm fertilization ability and can be used as potential biomarkers to evaluate male fertility. The role of cysteine-rich secretory protein 3 (CRISP3) in male reproduction remains unknown. This study aimed to investigate the role of CRISP3 in the reproductive performance of boars. Our results showed that the CRISP3 protein content was significantly and positively correlated with boar fertility, sow delivery rate, and litter size. CRISP3 is highly expressed in the bulbourethral gland of adult boars and is enriched in the seminal plasma. It is localized in the post-acrosomal region of the sperm head and migrates to the anterior end of the tail after capacitation. The CRISP3 recombinant protein did not affect sperm motility and cleavage rate, but it significantly downregulated the mRNA expression of inflammatory factors IL-α, IL-1β, and IL-6 and the protein expression of IL-α and IL-6 in lipopolysaccharide (LPS)-induced RAW264.7 cells, indicating that CRISP3 has an immunomodulatory function. In conclusion, our study suggests that semen CRISP3 protein levels positively correlate with reproductive performance, which may be achieved by regulating immune responses in the female reproductive tract.

CAP superfamily proteins from venomous animals: Who we are and what to do?

Cysteine-rich secretory proteins (CRISPs), antigen 5 (Ag5), and pathogenesis-related (PR-1) superfamily proteins (CAP superfamily proteins) are found in diverse species across the bacterial, fungal, plant, mammalian, and venomous animal kingdoms. Notably, CAP proteins are found in a remarkable range of species across the venomous animal kingdom and are present almost ubiquitously in venoms, even when venoms are produced in very small quantities. Meanwhile, in comparison to mammals, venomous animals are underappreciated and easy to ignore. Overwhelming evidence suggests that CAP proteins derived from venomous animals exhibit diverse activities, including ion channel, inflammatory, proteolysis, and immune regulatory activities. To understand the potential biological functions of CAP proteins in venom more effectively, we need to examine the significance of the evolution of venomous animals in the animal kingdom, for their survival. In this article, we will review the current status of research on CAP proteins in venomous animals, including their isolation, characterization, known biological activities, and sequence alignments. We will also discuss the rapid evolution of CAP proteins with varied subtypes in venomous animals. A treasure trove of information can be obtained by studying the CAP proteins in venomous animals; hence, it is necessary to explore these proteins further.

Leveraging epigenetics to enhance the efficacy of cancer-testis antigen: a potential candidate for immunotherapy

Ovarian cancer is the most lethal gynecological malignancy in women. The phenotype is characterized by delayed diagnosis, recurrence and drug resistance. Inherent immunogenicity potential, oncogenic function and expression of cancer-testis/germline antigen (CTA) in ovarian cancer render them a potential candidate for immunotherapy. Revolutionary clinical findings indicate that tumor antigen-mediated T-cell and dendritic cell-based immunotherapeutic approaches provide an excellent strategy for targeting tumors. Currently, dendritic cell vaccination for the treatment of B-cell lymphoma and CTA-based T-cell receptor transduced T-cell therapy involving MAGE-A4 and NY-ESO-1 are well documented and shown to be effective. This review highlighted the mechanical aspects of epigenetic drugs that can elicit a CTA-based humoral and cellular immune response and implicate T-cell and dendritic cell-based immunotherapeutic approaches.

Cysteine-Rich Secretory Proteins (CRISP) are Key Players in Mammalian Fertilization and Fertility

Mammalian fertilization is a complex process involving a series of successive sperm-egg interaction steps mediated by different molecules and mechanisms. Studies carried out during the past 30 years, using a group of proteins named CRISP (Cysteine-RIch Secretory Proteins), have significantly contributed to elucidating the molecular mechanisms underlying mammalian gamete interaction. The CRISP family is composed of four members (i.e., CRISP1-4) in mammals, mainly expressed in the male tract, present in spermatozoa and exhibiting Ca2+ channel regulatory abilities. Biochemical, molecular and genetic approaches show that each CRISP protein participates in more than one stage of gamete interaction (i.e., cumulus penetration, sperm-ZP binding, ZP penetration, gamete fusion) by either ligand-receptor interactions or the regulation of several capacitation-associated events (i.e., protein tyrosine phosphorylation, acrosome reaction, hyperactivation, etc.) likely through their ability to regulate different sperm ion channels. Moreover, deletion of different numbers and combination of Crisp genes leading to the generation of single, double, triple and quadruple knockout mice showed that CRISP proteins are essential for male fertility and are involved not only in gamete interaction but also in previous and subsequent steps such as sperm transport within the female tract and early embryo development. Collectively, these observations reveal that CRISP have evolved to perform redundant as well as specialized functions and are organized in functional modules within the family that work through independent pathways and contribute distinctly to fertility success. Redundancy and compensation mechanisms within protein families are particularly important for spermatozoa which are transcriptionally and translationally inactive cells carrying numerous protein families, emphasizing the importance of generating multiple knockout models to unmask the true functional relevance of family proteins. Considering the high sequence and functional homology between rodent and human CRISP proteins, these observations will contribute to a better understanding and diagnosis of human infertility as well as the development of new contraceptive options.

Expression profiling of pathogenesis-related Protein-1 (PR-1) genes from Solanum tuberosum reveals its critical role in phytophthora infestans infection

Pathogen-related (PR) proteins are an integral part of plants' defense mechanisms against various types of biotic and abiotic stresses. A little is known about the importance of these PR proteins in potato defense mechanisms. In the current study, a total of 22 pathogenesis-related 1 genes were identified in the potato genome. All identified proteins possessed the CAP superfamily domain with some other motifs. The cis-acting elements analysis identified several stress-responsive elements, including MYB, ABRE, and MeJRE. The gene duplication events demonstrated purifying and positive selection pressure. Expression profiling showed high transcripts level in root compared to other tissues; however, some genes have tissue-specific expression. Furthermore, the PR-1-5 gene is transcriptionally induced under Phytophthora infestans stress and hormonal (ABA and IAA) treatments. The Real-Time qPCR analysis also validated the RNA-seq data results of genes with maximum expression in roots compared to leaves and stems. The current study results provided basic data for functional characterization and can also use as a reference study for other important crops.

Differential gene expression and network-based analyses of the placental transcriptome reveal distinct potential biomarkers for gestationaldiabetes mellitus

AIMS

Gestational diabetes mellitus (GDM) is a common complication during pregnancy affecting the mother and fetus. With the problems encountered with the oral glucose tolerance test (OGTT), we aim to identify potential early biomarkers of GDM.

METHODS

A cross-sectional study was conducted among 80 pregnant women. Blood samples were collected every trimester, and total RNA was isolated. After quality control and library preparation, next-generation sequencing was performed. Differential expression analysis was done. Enriched Gene Ontology: Biological Processes (GO: BP) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were identified. Gene co-expression networks were constructed. Protein-protein Interaction (PPI) networks were then built from modules significantly correlated with Hemoglobin A1c. Genes with the highest degree of interaction were identified as hub genes.

RESULTS

IGKV2D-28 and PTPRG were consistently differentially expressed among the three comparisons. Top enriched GO: BP terms and KEGG pathways are linked to immune responses. Orange (r = 0.59, p = 0.02) and purple modules (r = 0.41, p = 0.02) of the GDM cohorts in the first and second trimesters, respectively, significantly correlated with Hemoglobin A1c. HDAC8 of the orange module and MPO and CRISP3 of the purple module were identified as hub genes.

CONCLUSIONS

In this study, potential biomarkers of GDM were identified, namely, IGKV2D-28, PTPRG, HDAC8, MPO, and CRISP3.

Drosophila Accessory Gland: A Complementary In Vivo Model to Bring New Insight to Prostate Cancer

Prostate cancer is the most common cancer in aging men. Despite recent progress, there are still few effective treatments to cure its aggressive and metastatic stages. A better understanding of the molecular mechanisms driving disease initiation and progression appears essential to support the development of more efficient therapies and improve patient care. To do so, multiple research models, such as cell culture and mouse models, have been developed over the years and have improved our comprehension of the biology of the disease. Recently, a new model has been added with the use of the Drosophila accessory gland. With a high level of conservation of major signaling pathways implicated in human disease, this functional equivalent of the prostate represents a powerful, inexpensive, and rapid in vivo model to study epithelial carcinogenesis. The purpose of this review is to quickly overview the existing prostate cancer models, including their strengths and limitations. In particular, we discuss how the Drosophila accessory gland can be integrated as a convenient complementary model by bringing new understanding in the mechanisms driving prostate epithelial tumorigenesis, from initiation to metastatic formation.

Screening differentially expressed proteins of coronary heart disease with congenital cold syndrome based on tandem mass tag (TMT) technology

In our previous studies, we discovered the congenital cold syndrome (CCS), which is characterized by 'qi deficiency and qi stagnation, mixed cold and heat.' And there is a type of syndrome with special incidence characteristic. However, the diagnosis of CCS still lacks an objective basis. In this study, we performed Tandem Mass Tag (TMT) based on quantitative proteomics technology to screen the significantly differentially expressed proteins (DEPs) in serum of patients with coronary heart disease (CHD) patients with CCS, patients with heart and kidney yang deficiency, and healthy people. A total of 22 DEPs (nine upregulated and 13 downregulated) were identified between patients with CCS and healthy subjects. Next, we performed GO and KEGG pathway enrichment analysis, we found the primary functions of DEPs of CCS were binding, catalytic activity, and molecular function regulator. These DEPs were mainly involved in important biological processes, such as cellular process, response to stimulus, localization, metabolic process, and biological regulation. The KEGG analysis revealed that the DEPs showed significant changes in fructose and mannose metabolism, Pentose phosphate pathway, and Arrhythmogenic right ventricular cardiomyopathy. After parallel reaction monitoring (PRM) verification, four upregulated target proteins (ALDOA, PCYOX1, Crisp3 and IGLV4-69) and three downregulated proteins (ALDOC, ADAMTSL-2 and C3) were accurately identified. These proteins were mainly related to immune response and glucose metabolism. These DEPs could be the marker proteins of coronary heart disease with CCS. This findings help to reveal the pathogenesis of CHD with CCS and provide potential therapeutic targets.

The functions of CAP superfamily proteins in mammalian fertility and disease

BACKGROUND

Members of the cysteine-rich secretory proteins (CRISPS), antigen 5 (Ag5) and pathogenesis-related 1 (Pr-1) (CAP) superfamily of proteins are found across the bacterial, fungal, plant and animal kingdoms. Although many CAP superfamily proteins remain poorly characterized, over the past decade evidence has accumulated, which provides insights into the functional roles of these proteins in various processes, including fertilization, immune defence and subversion, pathogen virulence, venom toxicology and cancer biology.

OBJECTIVE AND RATIONALE

The aim of this article is to summarize the current state of knowledge on CAP superfamily proteins in mammalian fertility, organismal homeostasis and disease pathogenesis.

SEARCH METHODS

The scientific literature search was undertaken via PubMed database on all articles published prior to November 2019. Search terms were based on following keywords: 'CAP superfamily', 'CRISP', 'Cysteine-rich secretory proteins', 'Antigen 5', 'Pathogenesis-related 1', 'male fertility', 'CAP and CTL domain containing', 'CRISPLD1', 'CRISPLD2', 'bacterial SCP', 'ion channel regulator', 'CatSper', 'PI15', 'PI16', 'CLEC', 'PRY proteins', 'ASP proteins', 'spermatogenesis', 'epididymal maturation', 'capacitation' and 'snake CRISP'. In addition to that, reference lists of primary and review article were reviewed for additional relevant publications.

OUTCOMES

In this review, we discuss the breadth of knowledge on CAP superfamily proteins with regards to their protein structure, biological functions and emerging significance in reproduction, health and disease. We discuss the evolution of CAP superfamily proteins from their otherwise unembellished prokaryotic predecessors into the multi-domain and neofunctionalized members found in eukaryotic organisms today. At least in part because of the rapid evolution of these proteins, many inconsistencies in nomenclature exist within the literature. As such, and in part through the use of a maximum likelihood phylogenetic analysis of the vertebrate CRISP subfamily, we have attempted to clarify this confusion, thus allowing for a comparison of orthologous protein function between species. This framework also allows the prediction of functional relevance between species based on sequence and structural conservation.

WIDER IMPLICATIONS

This review generates a picture of critical roles for CAP proteins in ion channel regulation, sterol and lipid binding and protease inhibition, and as ligands involved in the induction of multiple cellular processes.

Functional redundancy and compensation: Deletion of multiple murine Crisp genes reveals their essential role for male fertility

Mammalian Cysteine-RIch Secretory Protein (CRISP) family includes four members present in sperm and reported to regulate Ca²⁺ channels and fertilization. Based on our previous observations using single knockouts models and suggesting the existence of functional compensation among CRISP proteins, we investigated their relevance for male fertility by generating multiple Crisp gene mutants by CRISPR/Cas9 technology. Whereas targeting of Crisp1 and Crisp3 yielded subfertile males with early embryo developmental defects, the same deletion in zygotes from fertile Crisp2^-/- .Crisp4^-/- mice led to the generation of both triple and quadruple knockout mice exhibiting a complete or severe disruption of male fertility due to a combination of sperm transport, fertilization, and embryo developmental defects linked to intracellular Ca²⁺ dysregulation. These observations reveal that CRISP proteins are essential for male fertility and organize in functional modules that contribute distinctly to fertility success, bringing insights into the mechanisms underlying functional redundancy/compensation in protein families and emphasizing the importance of generating multiple and not just single knockout which might be masking the true functional relevance of family genes.

Modahl C, Maenaka K, Aoki-Shioi N. Cysteine-Rich Secretory Proteins (CRISPs) From Venomous Snakes: An Overview of the Functional Diversity in A Large and Underappreciated Superfamily

The CAP protein superfamily (Cysteine-rich secretory proteins (CRISPs), Antigen 5 (Ag5), and Pathogenesis-related 1 (PR-1) proteins) is widely distributed, but for toxinologists, snake venom CRISPs are the most familiar members. Although CRISPs are found in the majority of venoms, very few of these proteins have been functionally characterized, but those that have been exhibit diverse activities. Snake venom CRISPs (svCRISPs) inhibit ion channels and the growth of new blood vessels (angiogenesis). They also increase vascular permeability and promote inflammatory responses (leukocyte and neutrophil infiltration). Interestingly, CRISPs in lamprey buccal gland secretions also manifest some of these activities, suggesting an evolutionarily conserved function. As we strive to better understand the functions that CRISPs serve in venoms, it is worth considering the broad range of CRISP physiological activities throughout the animal kingdom. In this review, we summarize those activities, known crystal structures and sequence alignments, and we discuss predicted functional sites. CRISPs may not be lethal or major components of venoms, but given their almost ubiquitous occurrence in venoms and the accelerated evolution of svCRISP genes, these venom proteins are likely to have functions worth investigating.

The expression of Cysteine-Rich Secretory Protein 2 (CRISP2) and miR-582-5p in seminal plasma fluid and spermatozoa of infertile men

Cysteine-Rich Secretory Protein 2 (CRISP2) plays an important role in the morphology and motion of male ejaculated spermatozoa. The association of its expression with some miRNAs is also well known. The aim of this study was to determine the expression of CRISP2 and mir-582 in the seminal plasma fluid and spermatozoa of three groups of infertile men and the possible association of their expressions. In this experimental study, the expression of CRISP2 in seminal plasma fluid and spermatozoa of 17 men with asthenozoospermia, 15 men with teratozoospermia, 17 men with teratoasthenozoospermia, and 18 infertile individuals with normozoospermia were measured using western blotting. Then by using bioinformatics studies, miR-582-5p was nominated as a CRISP2-associated miRNA, and its expression was evaluated by means of Real-Time PCR. Comparison of expression of CRISP2 and miRNA-582 in the studied groups was analyzed by t-test and Mann-Whitney U test. The expression of CRISP2 showed a significant reduction in the spermatozoa and seminal plasma fluid of all three groups, (p < 0.05). MiR-582-5p expression significantly increased in teratozoospermia patients (<0.05), and significantly decreased in teratoasthenozoospermia patients (p < 0.05). Meanwhile, changes in the expression of miR-582-5p in teratoasthenozoospermia individuals was associated with a decrease in the expression of CRISP2, which could represent the potential role of miR-582-5p in regulation of CRISP2 expression in teratoasthenozoospermia individuals.

Dysregulated Transcriptional Control in Prostate Cancer

Recent advances in whole-genome and transcriptome sequencing of prostate cancer at different stages indicate that a large number of mutations found in tumors are present in non-protein coding regions of the genome and lead to dysregulated gene expression. Single nucleotide variations and small mutations affecting the recruitment of transcription factor complexes to DNA regulatory elements are observed in an increasing number of cases. Genomic rearrangements may position coding regions under the novel control of regulatory elements, as exemplified by the TMPRSS2-ERG fusion and the amplified enhancer identified upstream of the androgen receptor (AR) gene. Super-enhancers are increasingly found to play important roles in aberrant oncogenic transcription. Several players involved in these processes are currently being evaluated as drug targets and may represent new vulnerabilities that can be exploited for prostate cancer treatment. They include factors involved in enhancer and super-enhancer function such as bromodomain proteins and cyclin-dependent kinases. In addition, non-coding RNAs with an important gene regulatory role are being explored. The rapid progress made in understanding the influence of the non-coding part of the genome and of transcription dysregulation in prostate cancer could pave the way for the identification of novel treatment paradigms for the benefit of patients.

Major seminal plasma proteome of rabbits and associations with sperm quality

The present study was conducted to describe the major seminal plasma proteome of rabbits and potential associations between seminal proteins and semen criteria. Semen samples were collected from 18 New Zealand adult rabbits, and seminal plasma proteins were analyzed by 2-D SDS-PAGE and tandem mass spectrometry. Sperm motility, vigor, concentration, morphology and membrane sperm viability were evaluated. Rabbits ejaculated 364 ± 70 million sperm/ml, with 81 ± 6.1% motile cells, 3.8 ± 0.2 vigor and 66.7 ± 2.5% sperm with normal morphology. Based on the viability and acrosome integrity assay, there were 65.8 ± 2.5% live sperm with intact acrosome and most spermatozoa had both intact acrosome and functional membrane. On average, 2-D gels of rabbit seminal plasma had 232 ± 69.5 spots, as determined by PDQuest software (Bio Rad, USA). Mass spectrometry allowed the identification of 137 different proteins. The most abundant proteins in rabbit seminal plasma were hemoglobin subunit zeta-like, annexins, lipocalin, FAM115 protein and albumin. The intensity of the spots associated with these five proteins represented 71.5% of the intensity of all spots detected in the master gel. Multiple regression models were estimated using sperm traits as dependent variables and seminal plasma proteins as independent ones. Also, sperm motility had positive association with beta-nerve growth factor and cysteine-rich secretory protein 1-like and a negative one with galectin-1. The percentage of rabbit sperm with intact membrane was related to seminal plasma protein FAM115 complex and tropomyosin. Then, the population of morphologically normal sperm in rabbit semen was positively linked to carcinoembryonic antigen-related cell adhesion molecule 6-like and down regulated by seminal plasma isocitrate dehydrogenase. Based on another regression model, the variation in the percentage of live sperm with intact acrosome was partially explained by the amount of leukocyte elastase inhibitor and the peptidyl-prolyl cis-trans isomerase A in the rabbit seminal fluid. The current study reports the identification of 137 proteins of rabbit seminal plasma. Major proteins of seminal secretion relate primarily to prevention of damages caused by lipid peroxide radicals and oxidative stress, membrane functionality, transport of lipids to the sperm membrane and temperature regulation. Moreover, finding seminal plasma proteins as indicators of semen parameters will improve assisted reproductive technologies.

Crystal structure of the complex between venom toxin and serum inhibitor from Viperidae snake

Venomous snakes have endogenous proteins that neutralize the toxicity of their venom components. We previously identified five small serum proteins (SSP-1-SSP-5) from a highly venomous snake belonging to the family Viperidae as inhibitors of various toxins from snake venom. The endogenous inhibitors belong to the prostate secretory protein of 94 amino acids (PSP94) family. SSP-2 interacts with triflin, which is a member of the cysteine-rich secretory protein (CRISP) family that blocks smooth muscle contraction. However, the structural basis for the interaction and the biological roles of these inhibitors are largely unknown. Here, we determined the crystal structure of the SSP-2-triflin complex at 2.3 Å resolution. A concave region centrally located in the N-terminal domain of triflin is fully occupied by the terminal β-strands of SSP-2. SSP-2 does not bind tightly to the C-terminal cysteine-rich domain of triflin; this domain is thought to be responsible for its channel-blocker function. Instead, the cysteine-rich domain is tilted 7.7° upon binding to SSP-2, and the inhibitor appears to sterically hinder triflin binding to calcium channels. These results help explain how an endogenous inhibitor prevents the venomous protein from maintaining homeostasis in the host. Furthermore, this interaction also sheds light on the binding interface between the human homologues PSP94 and CRISP-3, which are up-regulated in prostate and ovarian cancers.

Secreted venom allergen-like proteins of helminths: Conserved modulators of host responses in animals and plants

Despite causing considerable damage to host tissue at the onset of parasitism, invasive helminths establish remarkably persistent infections in both animals and plants. Secretions released by these obligate parasites during host invasion are thought to be crucial for their persistence in infection. Helminth secretions are complex mixtures of molecules, most of which have unknown molecular targets and functions in host cells or tissues. Although the habitats of animal- and plant-parasitic helminths are very distinct, their secretions share the presence of a structurally conserved group of proteins called venom allergen-like proteins (VALs). Helminths abundantly secrete VALs during several stages of parasitism while inflicting extensive damage to host tissue. The tight association between the secretion of VALs and the onset of parasitism has triggered a particular interest in this group of proteins, as improved knowledge on their biological functions may assist in designing novel protection strategies against parasites in humans, livestock, and important food crops.

Biochemical and structural characterization of a protein complex containing a hyaluronidase and a CRISP-like protein isolated from the venom of the spider Acanthoscurria natalensis

Spider venoms are composed of a complex mixture of bioactive molecules. The structural and functional characterization of these molecules in the venom of the Brazilian spider Acanthoscurria natalensis, has been little explored. The venom was fractionated using reversed-phase liquid chromatography. The fraction with hyaluronidase activity was named AnHyal. The partial sequencing of AnHyal revealed the presence of a CRISP-like protein, in addition to hyaluronidase, comprising 67% coverage for hyaluronidase from Brachypelma vagans and 82% for CRISP-like protein from Grammostola rosea. 1D BN-PAGE zymogram assays of AnHyal confirmed the presence of enzymatically active 53 kDa monomer and 124 and 178 kDa oligomers. The decomposition of the complexes by 2D BN/SDS-PAGE zymogram assays showed two subunits, 53 (AnHyalH) and 44 kDa (AnHyalC), with sequence similarity to hyaluronidase and CRISP proteins, respectively. The secondary structure of AnHyal is composed by 36% of α-helix. AnHyal presented maximum activity at pH between 4.0 and 6.0 and 30 and 60 °C, showed specificity to hyaluronic acid substrate and presented a K_M of 617.9 μg/mL. Our results showed that hyaluronidase and CRISP proteins can form a complex and the CRISP protein may contribute to the enzymatic activity of AnHyalH.

Androgen receptor mediated epigenetic regulation of CRISP3 promoter in prostate cancer cells

Cysteine-rich secretory protein 3 (CRISP3) is one of the most upregulated genes in prostate cancer. Androgen receptor (AR) plays an important role not only in initial stages of prostate cancer development but also in the advanced stage of castration-resistant prostate cancer (CRPC). Role of AR in regulation of CRISP3 expression is not yet known. In order to understand the regulation of CRISP3 expression, various overlapping fragments of CRISP3 promoter were cloned in pGL3 luciferase reporter vector. All constructs were transiently and stably transfected in PC3 (CRISP3 negative) and LNCaP (CRISP3 positive) cell lines and promoter activity was measured by luciferase assay. Promoter activity of LNCaP stable clones was significantly higher than PC3 stable clones. Further in CRISP3 negative PC3 and RWPE-1 cells, CRISP3 promoter was shown to be silenced by histone deacetylation. Treatment of LNCaP cells with DHT resulted in increase in levels of CRISP3 transcript and protein. AR dependency of CRISP3 promoter was also evaluated in LNCaP stable clones by luciferase assay. To provide molecular evidence of epigenetic regulation of CRISP3 promoter and its response to DHT, ChIP PCR was performed in PC3 and LNCaP cells. Our results demonstrate that CRISP3 expression in prostate cancer cells is androgen dependent and in AR positive cells, CRISP3 promoter is epigenetically regulated by AR.

Quantitative evolutionary proteomics of seminal fluid from primates with different mating systems

BACKGROUND

Genomic data from various organisms have been used to study how sexual selection has shaped genetic diversity in reproductive proteins, and in particular, to elucidate how mating systems may have influenced evolution at the molecular and phenotypic levels. However, large-scale proteomic data including protein identifications and abundances are only now entering the field of evolutionary and comparative genomics. Variation in both protein sequence and expression level may play important roles in the evolution of sexual traits and behaviors.

RESULTS

Here, we broadly analyze the components of seminal fluid from primates with diverse mating systems ranging from monogamous to polygynous, and include genomics, proteomics, phylogenetic and quantitative characters into our framework. Our analyses show that seminal fluid proteins are undergoing rapid evolution and some of these quickly evolving proteins may be influenced by sexual selection. Through evolutionary analyses and protein abundance differences, we identified 84 genes whose evolutionary rates or expression levels were correlated with mating system and other sexual characters. We found that many proteins differ in abundance between monogamous and polygynous primate mating systems. Many of these proteins are enriched in the copulatory plug pathway, which suggests that post-zygotic selective barriers are important regardless of mating system type.

CONCLUSIONS

This work is the first to comprehensively compare seminal fluid proteins between human and non-human primates using high-throughput proteomics. Our findings highlight the impact of mating system variation on seminal fluid protein evolution and abundance.

Multiomics analysis of the giant triton snail salivary gland, a crown-of-thorns starfish predator

The giant triton snail (Charonia tritonis) is one of the few natural predators of the adult Crown-of-Thorns starfish (COTS), a corallivore that has been damaging to many reefs in the Indo-Pacific. Charonia species have large salivary glands (SGs) that are suspected to produce either a venom and/or sulphuric acid which can immobilize their prey and neutralize the intrinsic toxic properties of COTS. To date, there is little information on the types of toxins produced by tritons. In this paper, the predatory behaviour of the C. tritonis is described. Then, the C. tritonis SG, which itself is made up of an anterior lobe (AL) and posterior lobe (PL), was analyzed using an integrated transcriptomics and proteomics approach, to identify putative toxin- and feeding-related proteins. A de novo transcriptome database and in silico protein analysis predicts that ~3800 proteins have features consistent with being secreted. A gland-specific proteomics analysis confirmed the presence of numerous SG-AL and SG-PL proteins, including those with similarity to cysteine-rich venom proteins. Sulfuric acid biosynthesis enzymes were identified, specific to the SG-PL. Our analysis of the C. tritonis SG (AL and PL) has provided a deeper insight into the biomolecular toolkit used for predation and feeding by C. tritonis.

Comparative expression profiling of testis-enriched genes regulated during the development of spermatogonial cells

The testis has been identified as the organ in which a large number of tissue-enriched genes are present. However, a large portion of transcripts related to each stage or cell type in the testis still remains unknown. In this study, databases combined with confirmatory measurements were used to investigate testis-enriched genes, localization in the testis, developmental regulation, gene expression profiles of testicular disease, and signaling pathways. Our comparative analysis of GEO DataSets showed that 24 genes are predominantly expressed in testis. Cellular locations of 15 testis-enriched proteins in human testis have been identified and most of them were located in spermatocytes and round spermatids. Real-time PCR revealed that expressions of these 15 genes are significantly increased during testis development. Also, an analysis of GEO DataSets indicated that expressions of these 15 genes were significantly decreased in teratozoospermic patients and polyubiquitin knockout mice, suggesting their involvement in normal testis development. Pathway analysis revealed that most of those 15 genes are implicated in various sperm-related cell processes and disease conditions. This approach provides effective strategies for discovering novel testis-enriched genes and their expression patterns, paving the way for future characterization of their functions regarding infertility and providing new biomarkers for specific stages of spematogenesis.

Male infertility-related molecules involved in sperm-oocyte fusion

Male infertility has become a very serious problem in the human reproduction system, but the molecular mechanism of infertility remains largely unknown. Fertilization is the phenomenon in which a sperm and oocyte find each other, interact, and fuse. Sperm-oocyte fusion-related factors on the sperm side play crucial roles in male infertility. For example, IZUMO1 is well-known as a sperm protein essential for fusion of a sperm and oocyte, but its dysfunction or mutation can result in male infertility. Recent studies showed a novel sperm protein named Bactericidal/permeability-increasing protein (BPI), which takes part in the sperm-oocyte fusion process. The complexity and expected redundancy of the factors involved makes the process intricate, with a still poorly understood mechanism, which is difficult to comprehend in full detail. This review summarizes the known molecules involved in the process of sperm-oocyte fusion, mainly focusing on the relevant factors on the sperm side, whose dysregulation may potentially be associated with male infertility. New insights may come from these molecules in this review, can facilitate the development of new treatments of male infertility, and may have a diagnostic value in infertility.

Purification and characterization of CRISP-3 from human seminal plasma and its real-time binding kinetics with PSP94

Cysteine-rich secretory proteins (CRISPs) have been postulated to have a role in male reproduction and prostate pathophysiology. Of the mammalian CRISPs, CRISP-3 levels in particular have been shown to be upregulated in prostate cancer. Efforts have been made to obtain highly pure CRISP-3 for gaining structure-function information of this protein. However, well characterized and highly pure protein is not available yet. CRISPs from snake venom have been purified using prostate secretory protein of 94 amino acids (PSP94) has been reported earlier. In the present study, CRISP-3 was purified to homogeneity from human seminal plasma using human PSP94-immnobilized affinity column. The molecular mass of the purified protein was determined by SDS-PAGE followed by immunoblotting and found to be ∼26kDa and ∼28kDa. The purity was further verified using MALDI-TOF MS analysis, where two peaks at m/z 25509 and 27715 were obtained. The lower molecular weight peak corresponds to the calculated molecular mass of CRISP-3 (∼26kDa); whereas the higher molecular weight peak was confirmed to be the glycosylated form (∼28kDa) from the deglycosylation experiment. Binding of PSP94 in increasing concentrations to purified CRISP-3 immobilized chip was further validated using surface plasmon resonance. The kinetics data suggested that purified CRISP-3 binds specifically and with high affinity to PSP94. In conclusion, a homogeneous preparation of highly pure CRISP-3 protein is obtained from human seminal plasma.

The Drosophila Accessory Gland as a Model for Prostate Cancer and Other Pathologies

The human prostate is a gland of the male reproductive tract, which together with the seminal vesicles, is responsible for most seminal fluid production. It is a common site of cancer, and unlike other glands, it typically enlarges in aging men. In flies, the male accessory glands make many major seminal fluid components. Like their human equivalents, they secrete proteins from several conserved families, including proteases, lectins, and cysteine-rich secretory proteins, some of which interact with sperm and affect fertility. A key protein, sex peptide, is not conserved in vertebrates but plays a central role in mediating long-term effects on females after mating. Although postmitotic, one epithelial cell type in the accessory glands, the secondary cell, continues to grow in adults. It secretes microvesicles called exosomes from the endosomal multivesicular body, which, after mating, fuse with sperm. They also appear to affect female postmating behavior. Remarkably, the human prostate epithelium also secretes exosomes, which fuse to sperm in vitro to modulate their activity. Exosomes from prostate and other cancer cells are increasingly proposed to play fundamental roles in modulating the tumor microenvironment and in metastasis. Here we review a diverse accessory gland literature, which highlights functional analogies between the male reproductive glands of flies and humans, and a critical role for extracellular vesicles in allowing seminal fluid to promote male interests within the female. We postulate that secondary cells and prostate epithelial cells use common mechanisms to control growth, secretion, and signaling, which are relevant to prostate and other cancers, and can be genetically dissected in the uniquely tractable fly model.

From the epididymis to the egg: participation of CRISP proteins in mammalian fertilization

Mammalian fertilization is a complex process that involves different steps of interaction between the male and female gametes. In spite of its relevance, the molecular mechanisms underlying this process still remain to be elucidated. The present review describes the contribution of our laboratory to the understanding of mammalian fertilization using Cysteine-RIch Secretory Proteins (CRISP) as model molecules. Substantial evidence obtained from in vitro assays and knockout models shows that epididymal CRISP1 associates with the sperm surface with two different affinities during maturation, and participates in the regulation of signaling pathways during capacitation as well as in both sperm-zona pellucida interaction and gamete fusion. These observations can be extended to humans as judged by our findings showing that the human homolog of the rodent protein (hCRISP1) is also involved in both stages of fertilization. Evidence supports that other members of the CRISP family secreted in the testis (CRISP2), epididymis (CRISP3-4) or during ejaculation (CRISP3) are also involved in sperm-egg interaction, supporting the existence of a functional redundancy and cooperation between homolog proteins ensuring the success of fertilization. Together, our observations indicate that CRISP proteins accompany spermatozoa along their transit through both the male and female reproductive tracts. We believe these results not only contribute to a better mechanistic understanding of fertilization but also support CRISP proteins as excellent candidates for future research on infertility and contraception.

The Immunogenicity of CRISP1 Plasmid-Based Contraceptive Vaccine can be Improved When Using Chitosan Nanoparticles as the Carrier

PROBLEM

To evaluate the effectiveness and security of a contraceptive vaccine using plasmid DNA encoding mouse CRISP1 as antigen and chitosan nanoparticles as the carrier.

METHOD OF STUDY

Chitosan-pcDNA3.1-mCRISP1 Nanoparticles (CS-DNA NPs) were prepared and characterized in terms of morphology, zeta potential, polydispersity index, and binding capacity of pDNA. The cytotoxicity and gene transfer capability of CS-DNA NPs were assessed in COS-7 cells compared to Lipofectamine 2000(™) . Four groups of mice received three injections of 0.9% normal saline, pcDNA3.1 vector, pcDNA3.1-CRISP1, or CS-DNA NPs, respectively. ELISA was used to examine the immune responses. Fertility and mean litter size were analyzed by natural mating.

RESULTS

CS-DNA NPs have a spherical or elliptical shape with a mean diameter of 189.3 nm, positive zeta potential, and good DNA condensation. It also showed high DNAse resistance and good transfection efficiency without cell toxicity. The titers of anti-mCRISP1 antibodies from CS-DNA NP-immunized mice were significantly higher than that of pcDNA3.1-CRISP1 group. Male and female CS-DNA NP-immunized animals were recognized with a statistically significant reduction in their fertility compared with pcDNA3.1-CRISP1-immunized mice.

CONCLUSION

This study demonstrated that using chitosan-DNA nanoparticles as the carrier can improve the immunogenicity of mCRISP1 DNA contraceptive vaccine with good security.

Fertilization defects in sperm from Cysteine-rich secretory protein 2 (Crisp2) knockout mice: implications for fertility disorders

STUDY HYPOTHESIS

We hypothesize that fertility disorders in patients with aberrant expression of Cysteine-RIch Secretory Protein 2 (CRISP2) could be linked to the proposed functional role of this protein in fertilization.

STUDY FINDING

Our in vivo and in vitro observations reveal that Crisp2-knockout mice exhibit significant defects in fertility-associated parameters under demanding conditions, as well as deficiencies in sperm fertilizing ability, hyperactivation development and intracellular Ca(2+) regulation.

WHAT IS KNOWN ALREADY

Testicular CRISP2 is present in mature sperm and has been proposed to participate in gamete fusion in both humans and rodents. Interestingly, evidence in humans shows that aberrant expression of CRISP2 is associated with male infertility.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

A mouse line carrying a deletion in the sixth exon of the Crisp2 gene was generated. The analyses of the reproductive phenotype of Crisp2(-/-) adult males included the evaluation of their fertility before and after being subjected to unilateral vasectomy, in vivo fertilization rates obtained after mating with either estrus or superovulated females, in vitro sperm fertilizing ability and different sperm functional parameters associated with capacitation such as tyrosine phosphorylation (by western blot), acrosome reaction (by Coomassie Blue staining), hyperactivation (by computer-assisted sperm analysis) and intracellular Ca(2+) levels (by flow cytometry).

MAIN RESULTS AND THE ROLE OF CHANCE

Crisp2(-/-) males presented normal fertility and in vivo fertilization rates when mated with estrus females. However, the mutant mice showed clear defects in those reproductive parameters compared with controls under more demanding conditions, i.e. when subjected to unilateral vasectomy to reduce the number of ejaculated sperm (n = 5; P< 0.05), or when mated with hormone-treated females containing a high number of eggs in the ampulla (n ≥ 5; P< 0.01). In vitro fertilization studies revealed that Crisp2(-/-) sperm exhibited deficiencies to penetrate the egg vestments (i.e. cumulus oophorus and zona pellucida) and to fuse with the egg (n ≥ 6; P< 0.01). Consistent with this, Crisp2-null sperm showed lower levels of hyperactivation (n = 7; P< 0.05), a vigorous motility required for penetration of the egg coats, as well as a dysregulation in intracellular Ca(2+) levels associated with capacitation (n = 5; P< 0.001).

LIMITATIONS, REASONS FOR CAUTION

The analysis of the possible mechanisms involved in fertility disorders in men with abnormal expression of CRISP2 was carried out in Crisp2 knockout mice due to the ethical and technical problems inherent to the use of human gametes for fertilization studies.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings in mice showing that Crisp2(-/-) males exhibit fertility and fertilization defects under demanding conditions support fertilization defects in sperm as a mechanism underlying infertility in men with aberrant expression of CRISP2. Moreover, our observations in mice resemble the situation in humans where fertility disorders can or cannot be detected depending on the accumulation of own individual defects or the fertility status of the partner. Finally, the fact that reproductive defects in mice are masked by conventional mating highlights the need of using different experimental approaches to analyze male fertility.

STUDY FUNDING AND COMPETING INTERESTS

This study was supported by the World Health Organization (H9/TSA/037), the National Research Council of Argentina (PIP 2009-290), the National Agency for Scientific and Technological Promotion of Argentina (PICT 2011, 2023) and the Rene Baron Foundation to P.S.C. and by the MEXT of Japan to M.I. The authors declare that there are no conflicts of interest.

Cysteine-rich secretory protein 3 plays a role in prostate cancer cell invasion and affects expression of PSA and ANXA1

Cysteine-rich secretory protein 3 (CRISP-3) is upregulated in prostate cancer as compared to the normal prostate tissue. Higher expression of CRISP-3 has been linked to poor prognosis and hence it has been thought to act as a prognostic marker for prostate cancer. It is proposed to have a role in innate immunity but its role in prostate cancer is still unknown. In order to understand its function, its expression was stably knocked down in LNCaP cells. CRISP-3 knockdown did not affect cell viability but resulted in reduced invasiveness. Global gene expression changes upon CRISP-3 knockdown were identified by microarray analysis. Microarray data were quantitatively validated by evaluating the expression of seven candidate genes in three independent stable clones. Functional annotation of the differentially expressed genes identified cell adhesion, cell motility, and ion transport to be affected among other biological processes. Prostate-specific antigen (PSA, also known as Kallikrein 3) was the top most downregulated gene whose expression was also validated at protein level. Interestingly, expression of Annexin A1 (ANXA1), a known anti-inflammatory protein, was upregulated upon CRISP-3 knockdown. Re-introduction of CRISP-3 into the knockdown clone reversed the effect on invasiveness and also led to increased PSA expression. These results suggest that overexpression of CRISP-3 in prostate tumor may maintain higher PSA expression and lower ANXA1 expression. Our data also indicate that poor prognosis associated with higher CRISP-3 expression could be due to its role in cell invasion.

Endometrial CRISP3 is regulated throughout the mouse estrous and human menstrual cycle and facilitates adhesion and proliferation of endometrial epithelial cells

The endometrium (the mucosal lining of the uterus) is a dynamic tissue that undergoes extensive remodeling, secretory transformation in preparation for implantation of an embryo, inflammatory and proteolytic activity during menstruation, and rapid postmenstrual repair. A plethora of local factors influence these processes. Recently, a cysteine-rich protein, CRISP3, a clade of the CRISP, antigen 5, pathogenesis-related (CAP) protein superfamily, has been implicated in uterine function. The localization, regulation, and potential function of CRISP3 in both the human and mouse endometrium is described. CRISP3 localizes to the luminal and glandular epithelium of the endometrium within both species, with increased immunoreactivity during the proliferative phase of the human cycle. CRISP3 also localizes to neutrophils, particularly within the premenstrual human endometrium and during the postbreakdown repair phase of a mouse model of endometrial breakdown and repair. Endometrial CRISP3 is produced by primary human endometrial epithelial cells and secreted in vivo to accumulate in the uterine cavity. Secreted CRISP3 is more abundant in uterine lavage fluid during the proliferative phase of the menstrual cycle. Human endometrial epithelial CRISP3 is present in both a glycosylated and a nonglycosylated form in vitro and in vivo. Treatment of endometrial epithelial cells in vitro with recombinant CRISP3 enhances both adhesion and proliferation. These data suggest roles for epithelial and neutrophil-derived CRISP3 in postmenstrual endometrial repair and regeneration.

Cysteine-rich secretory protein 3 inhibits hepatitis C virus at the initial phase of infection

Hepatitis C virus (HCV) affects 2-3% of the global population. Approximately one-quarter of acute infections cause chronic hepatitis that leads to liver cirrhosis or hepatocellular carcinoma. The major obstacle of current research is the extremely narrow host tropism of HCV. A single HCV strain can replicate in the Huh7 human hepatoma cell line. Huh7 cells can be adapted under selective pressure in vitro to identify host factors that influence viral replication. Here, we extended this strategy to the in vivo condition and generated a series of cell lines by multiple rounds of adaptation in immunocompromised mice. Adaptation increased the cellular resistance to HCV infection. Microarray analyses revealed that the expression levels of several genes were associated with HCV resistance. Notably, up-regulation of the mRNA encoding cysteine-rich secretory protein 3 (CRISP3), a glycoprotein with unknown function that is secreted from multiple exocrine glands, was correlated with HCV resistance. The presence of CRISP3 in the culture medium limited HCV replication at the early phase of infection.

Antisperm antibodies: invaluable tools toward the identification of sperm proteins involved in fertilization

The identification of sperm proteins involved in fertilization has been the subject of numerous investigations. Much interest has been dedicated to naturally occurring antisperm antibodies (ASA) and their impact in fertility. Their presence in men and women has been associated with 2-50% of infertility cases. ASA may impair pre- and post-fertilization steps. Experimental models have been developed using sperm proteins as immunogens to evaluate their involvement in sperm function. Our team has pursued investigations to assess ASA presence in biological fluids from patients consulting for infertility and their effect on fertilization. We found ASA in follicular fluids with ability of inducing the acrosome reaction and blocking sperm-zona pellucida interaction and used them to identify sperm entities involved in these events. We generated and utilized antibodies against proacrosin/acrosin to characterize the sperm protease system. We implemented an ELISA to detect proacrosin/acrosin antibodies in human sera and evaluated their impact upon fertility by developing in vitro assays and a gene immunization model. This review presents a summary of ASA history, etiology, current approaches for detection and effects upon fertility. ASA (naturally occurring, generated by animal immunization and/or of commercial origin) are invaluable tools to understand the molecular basis of fertilization, better diagnose/treat immunoinfertility and develop immunocontraceptive methods.

Cysteine- rich secretory protein 3 (CRISP3), ERG and PTEN define a molecular subtype of prostate cancer with implication to patients' prognosis

Cysteine- rich secretory protein 3 (CRISP3) prognostic significance in prostate cancer (PCA) has generated mixed result. Herein, we investigated and independently validated CRISP3 expression in relation to ERG and PTEN genomic aberrations and clinical outcome. CRISP3 protein expression was examined by immunohistochemistry using a cohort of patients with localized PCA (n = 215) and castration resistant PCA (CRPC) (n = 46). The Memorial Sloan Kettering (MSKCC) and Swedish cohorts were used for prognostic validation. Results showed, CRISP3 protein intensity to be significantly associated with neoplastic epithelium, being highest in CRPC vs. benign prostate tissue (p < 0.0001), but was not related to Gleason score (GS). CRISP3 mRNA was significantly associated with higher GS (p = 0.022 in MSKCC, p = 1.1e-4 in Swedish). Significant association between CRISP3 expression and clinical outcome was documented at the mRNA but not the protein expression levels. CRISP3 mRNA expression was related to biochemical recurrence in the MSKCC (p = 0.038) and lethal disease in the Swedish cohort (p = 0.0086) and retained its prognostic value in the subgroup of patients with GS 6 & 7. Furthermore, CRISP3 protein and mRNA expression was significantly associated with positive ERG status and with PTEN deletions. Functional biology analysis documented phenylalanine metabolism as the most significant pathway governing high CRISP3 and ERG expression in this subtype of PCA. In conclusion, the combined status of CRISP3, ERG and PTEN define a molecular subtype of PCA with poorest and lethal outcome. Assessing their combined value may be of added value in stratifying patients into different prognostic groups and identify those with poorest clinical outcome.

Cysteine-rich secretory protein 3 overexpression is linked to a subset of PTEN-deleted ERG fusion-positive prostate cancers with early biochemical recurrence

The aim of this study was to determine whether cysteine-rich secretory protein 3 (CRISP3) expression is linked to clinically or molecularly relevant subgroups of prostate cancer. A tissue microarray representing samples from >10,000 prostate cancers from radical prostatectomy specimens with clinical follow-up data were analyzed for CRISP3 expression by immunohistochemistry. CRISP3 expression was also compared with key genomic alterations of prostate cancer. CRISP3 staining was found as weak in 15%, moderate in 8.5%, and strong in 7.2% of prostate cancers, whereas no expression was detected in normal prostate. Strong CRISP3 expression was linked to advanced tumor stage, high Gleason score, and positive surgical margin status (P<0.0001 each). There was a marked accumulation of high CRISP3 expression in PTEN-deleted ERG-positive tumors (P<0.0001). A total of, 21.7% of ERG-positive and PTEN-deleted cancers had strong CRISP3 expression, but only 10.4% of ERG-positive cancers without PTEN deletion (P<0.0001). The rate of high CRISP3 expression was 2.5% in ERG-negative cancers (P=0.0001; vs ERG-positive cancers). Accordingly, CRISP3 overexpression was associated with early prostate-specific antigen recurrence in all tumors (P=0.0013) as well as in ERG-negative (P=0.004) and ERG-positive cancers (P=0.0318). CRISP3 expression did not retain prognostic significance in models also involving PTEN deletions. Strong CRISP3 expression is associated with unfavorable tumor phenotype and early recurrence in prostate cancers. The tight link of strong CRISP3 expression to the ERG fusion-positive prostate cancers with PTEN deletions provides further evidence for the existence of molecularly distinct subgroups of prostate cancers.

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.

Non-enzymatic proteins from snake venoms: a gold mine of pharmacological tools and drug leads

Non-enzymatic proteins from snake venoms play important roles in the immobilization of prey, and include some large and well-recognized families of toxins. The study of such proteins has expanded not only our understanding of venom toxicity, but also the knowledge of normal and disease states in human physiology. In many cases their characterization has led to the development of powerful research tools, diagnostic techniques, and pharmaceutical drugs. They have further yielded basic understanding of protein structure-function relationships. Therefore a number of studies on these non-enzymatic proteins had major impact on several life science and medical fields. They have led to life-saving therapeutics, the Nobel prize, and development of molecular scalpels for elucidation of ion channel function, vasoconstriction, complement system activity, platelet aggregation, blood coagulation, signal transduction, and blood pressure regulation. Here, we identify research papers that have had significant impact on the life sciences. We discuss how these findings have changed the course of science, and have also included the personal recollections of the original authors of these studies. We expect that this review will provide impetus for even further exciting research on novel toxins yet to be discovered.

Identification and deletion of the major secreted protein of Pichia pastoris

A major contaminating host cell protein was identified in fed batch cultures of Pichia pastoris producing an antibody Fab fragment. Purification and peptide sequencing identified this protein to be related to the cysteine-rich secretory protein family. The same protein was also observed as one of the most abundantly secreted proteins in chemostat cultures of a wild type P. pastoris strain. It has an apparent molecular weight of 65 kDa, 2-fold higher than predicted from the amino acid sequence, which is due to high O-glycosylation. It was denominated extracellular protein X 1 (Epx1), as no clear function could be attributed to it. The EPX1 gene is upregulated in different stress situations, and the respective deletion strain was more susceptible than the wild type to the cell wall damaging agents Calcofluor white and Congo red. The EPX1 deletion strain (Δepx1) was evaluated for its suitability for recombinant protein production. No significant difference in growth and product formation was observed between the wild type and the Δepx1 strain. Batch purification of a Fab fragment produced in the Δepx1 strain highlighted its superior purity due to the decreased host cell protein load.

A PR-1-like protein of Fusarium oxysporum functions in virulence on mammalian hosts

The pathogenesis-related PR-1-like protein family comprises secreted proteins from the animal, plant, and fungal kingdoms whose biological function remains poorly understood. Here we have characterized a PR-1-like protein, Fpr1, from Fusarium oxysporum, an ubiquitous fungal pathogen that causes vascular wilt disease on a wide range of plant species and can produce life-threatening infections in immunocompromised humans. Fpr1 is secreted and proteolytically processed by the fungus. The fpr1 gene is required for virulence in a disseminated immunodepressed mouse model, and its function depends on the integrity of the proposed active site of PR-1-like proteins. Fpr1 belongs to a gene family that has expanded in plant pathogenic Sordariomycetes. These results suggest that secreted PR-1-like proteins play important roles in fungal pathogenicity.

Loss of cysteine-rich secretory protein 4 (Crisp4) leads to deficiency in sperm-zona pellucida interaction in mice

Mammalian sperm gain their ability to fertilize the egg during transit through the epididymis and by interacting with proteins secreted by the epididymal epithelial cells. Certain members of the CRISP (cysteine-rich secretory protein) family form the major protein constituent of the luminal fluid in the mammalian epididymis. CRISP4 is the newest member of the CRISP family expressed predominantly in the epididymis. Its structure and expression pattern suggest a role in sperm maturation and/or sperm-egg interaction. To study the relevance of CRISP4 in reproduction, we have generated a Crisp4 iCre knock-in mouse model through insertion of the iCre recombinase coding cDNA into the Crisp4 locus. This allows using the mouse line both as a Crisp4 deficient model and as an epididymis-specific iCre-expressing mouse line applicable for the generation of conditional, epididymis-specific knockout mice. We show that the loss of CRISP4 leads to a deficiency of the spermatozoa to undergo progesterone-induced acrosome reaction and to a decreased fertilizing ability of the sperm in the in vitro fertilization conditions, although the mice remain fully fertile in normal mating. However, removal of the egg zona pellucida returned the fertilization potential of the CRISP4-deficient spermatozoa, and accordingly we detected a reduced number of Crisp4-deficient spermatozoa bound to oocytes as compared with the wild-type spermatozoa. We also demonstrate that iCre recombinase is expressed in a pattern similar to endogenous Crisp4 and is able to initiate the recombination event with its target sequences in vivo.

Allurin, an amphibian sperm chemoattractant having implications for mammalian sperm physiology

Eggs of many species are surrounded by extracellular coats that emit ligands to which conspecific sperm respond by undergoing chemotaxis and changes in metabolism, motility, and acrosomal status in preparation for fertilization. Here we review methods used to measure sperm chemotaxis and focus on recent studies of allurin, a 21-kDa protein belonging to the Cysteine-RIch Secretory Protein (CRISP) family that has chemoattraction activity for both amphibian and mammalian sperm. Allurin is unique in being the first extensively characterized Crisp protein found in the female reproductive tract and is the product of a newly discovered amphibian gene within a gene cluster that has been largely conserved in mammals. Study of its expression, function, and tertiary structure could lead to new insights in the role of Crisp proteins in sperm physiology.

Ectopic pregnancy as a model to identify endometrial genes and signaling pathways important in decidualization and regulated by local trophoblast

The endometrium in early pregnancy undergoes decidualization and functional changes induced by local trophoblast, which are not fully understood. We hypothesized that endometrium from tubal ectopic pregnancy (EP) could be interrogated to identify novel genes and pathways involved in these processes. Gestation-matched endometrium was collected from women with EP (n = 11) and intrauterine pregnancies (IUP) (n = 13). RNA was extracted from the tissue. In addition, tissues were prepared for histological analysis for degree of decidualization. We compared a) the samples from EP that were decidualized (n = 6) with non-decidualized samples (n = 5), and b) the decidualized EP (n = 6) with decidualization-matched IUP (n = 6) samples using an Affymetrix gene array platform, with Ingenuity Pathway Analysis, combined with quantitative RT-PCR. Expression of PRL and IGFBP1 was used to confirm the degree of decidualization in each group. There were no differences in PRL or IGFBP1 expression in the decidualization-matched samples but a marked reduction (P<0.001) in the non-decidualized samples. Decidualization was associated with increased expression of 428 genes including SCARA5 (181-fold), DKK1 (71-fold) and PROK1 (32-fold), and decreased expression of 230 genes including MMP-7 (35-fold) and SFRP4 (21-fold). The top canonical pathways associated with these differentially expressed genes were Natural Killer Cell and Wnt/b-Catenin signaling. Local trophoblast was associated with much less alteration of endometrial gene expression with an increase in 56 genes, including CSH1 (8-fold), and a reduction in 29 genes including CRISP3 (8-fold). The top associated canonical pathway was Antigen Presentation. The study of endometrium from tubal EP may promote novel insights into genes involved in decidualization and those influenced by factors from neighboring trophoblast. This has afforded unique information not highlighted by previous studies and adds to our understanding of the endometrium in early pregnancy.

Cysteine-rich secretory protein-3 (CRISP3) is strongly up-regulated in prostate carcinomas with the TMPRSS2-ERG fusion gene

A large percentage of prostate cancers harbor TMPRSS2-ERG gene fusions, leading to aberrant overexpression of the transcription factor ERG. The target genes deregulated by this rearrangement, however, remain mostly unknown. To address this subject we performed genome-wide mRNA expression analysis on 6 non-malignant prostate samples and 24 prostate carcinomas with (n = 16) and without (n = 8) TMPRSS2-ERG fusion as determined by FISH. The top-most differentially expressed genes and their associations with ERG over-expression were technically validated by quantitative real-time PCR and biologically validated in an independent series of 200 prostate carcinomas. Several genes encoding metabolic enzymes or extracellular/transmembrane proteins involved in cell adhesion, matrix remodeling and signal transduction pathways were found to be co-expressed with ERG. Within those significantly over-expressed in fusion-positive carcinomas, CRISP3 showed more than a 50-fold increase when compared to fusion-negative carcinomas, whose expression levels were in turn similar to that of non-malignant samples. In the independent validation series, ERG and CRISP3 mRNA levels were strongly correlated (r_s = 0.65, p<0.001) and both were associated with pT3 disease staging. Furthermore, immunohistochemistry results showed CRISP3 protein overexpression in 63% of the carcinomas and chromatin immunoprecipitation with an anti-ERG antibody showed that CRISP3 is a direct target of the transcription factor ERG. We conclude that ERG rearrangement is associated with significant expression alterations in genes involved in critical cellular pathways that define a subset of locally advanced PCa. In particular, we show that CRISP3 is a direct target of ERG that is strongly overexpressed in PCa with the TMPRSS2-ERG fusion gene.