Fertilin beta and other ADAMs as integrin ligands: insights into cell adhesion and fertilization

Developmental Hurdles That Can Compromise Pregnancy during the First Month of Gestation in Cattle

Several key developmental events are associated with early embryonic pregnancy losses in beef and dairy cows. These developmental problems are observed at a greater frequency in pregnancies generated from in-vitro-produced bovine embryos. This review describes critical problems that arise during oocyte maturation, fertilization, early embryonic development, compaction and blastulation, embryonic cell lineage specification, elongation, gastrulation, and placentation. Additionally, discussed are potential remediation strategies, but unfortunately, corrective actions are not available for several of the problems being discussed. Further research is needed to produce bovine embryos that have a greater likelihood of surviving to term.

Positive selection on ADAM10 builds species recognition in the synchronous spawning coral Acropora

The reef-building coral Acropora is a broadcast spawning hermaphrodite including more than 110 species in the Indo-Pacific. In addition, many sympatric species show synchronous spawning. The released gametes need to mate with conspecifics in the mixture of the gametes of many species for their species boundaries. However, the mechanism underlying the species recognition of conspecifics at fertilization remains unknown. We hypothesized that rapid molecular evolution (positive selection) in genes encoding gamete-composing proteins generates polymorphic regions that recognize conspecifics in the mixture of gametes from many species. We identified gamete proteins of Acropora digitifera using mass spectrometry and screened the genes that support branch site models that set the "foreground" branches showing strict fertilization specificity. ADAM10, ADAM17, Integrin α9, and Tetraspanin4 supported branch-site model and had positively selected site(s) that produced polymorphic regions. Therefore, we prepared antibodies against the proteins of A. digitifera that contained positively selected site(s) to analyze their functions in fertilization. The ADAM10 antibody reacted only with egg proteins of A. digitifera, and immunohistochemistry showed ADAM10 localized around the egg surface. Moreover, the ADAM10 antibody inhibited only A. digitifera fertilization but not the relative synchronous spawning species A. papillare. This study indicates that ADAM10 has evolved to gain fertilization specificity during speciation and contributes to species boundaries in this multi-species, synchronous-spawning, and species-rich genus.

Oncogenic Role of ADAM32 in Hepatoblastoma: A Potential Molecular Target for Therapy

Outcomes of pediatric hepatoblastoma (HBL) have improved, but refractory cases still occur. More effective and safer drugs are needed that are based on molecular mechanisms. A disintegrin and metalloproteases (ADAMs) are expressed with high frequency in various human carcinomas and play an important role in cancer progression. In this study, we analyzed expression of ADAMs in HBL with a cDNA microarray dataset and found that the expression level of ADAM32 is particularly high. To investigate the role of ADAM32 in cancer, forced expression or knockdown experiments were conducted with HepG2 and HBL primary cells. Colony formation, cell migration and invasion, and cell viability were increased in HepG2 expressing ADAM32, whereas knockdown of ADAM32 induced a decrease in these cellular functions. Quantitative RT-PCR demonstrated an association between ADAM32 expression and the expression of genes related to cancer stem cells and epithelial–mesenchymal transition (EMT), suggesting a role of ADAM32 in cancer stemness and EMT. Furthermore, knockdown of ADAM32 increased cisplatin-induced apoptosis, and this effect was attenuated by a caspase-8 inhibitor, suggesting that ADAM32 plays a role in extrinsic apoptosis signaling. We conclude that ADAM32 plays a crucial role in progression of HBL, so it might be a promising molecular target in anticancer therapy.

Cell Fusion-Related Proteins and Signaling Pathways, and Their Roles in the Development and Progression of Cancer

Cell fusion is involved in many physiological and pathological processes, including gamete binding, and cancer development. The basic processes of cell fusion include membrane fusion, cytoplasmic mixing, and nuclear fusion. Cell fusion is regulated by different proteins and signaling pathways. Syncytin-1, syncytin-2, glial cell missing 1, galectin-1 and other proteins (annexins, myomaker, myomerger etc.) involved in cell fusion via the cyclic adenosine-dependent protein kinase A, mitogen-activated protein kinase, wingless/integrase-1, and c-Jun N-terminal kinase signaling pathways. In the progression of malignant tumors, cell fusion is essential during the organ-specific metastasis, epithelial-mesenchymal transformation, the formation of cancer stem cells (CSCs), cancer angiogenesis and cancer immunity. In addition, diploid cells can be induced to form polyploid giant cancer cells (PGCCs) via cell fusion under many kinds of stimuli, including cobalt chloride, chemotherapy, radiotherapy, and traditional Chinese medicine. PGCCs have CSC-like properties, and the daughter cells derived from PGCCs have a mesenchymal phenotype and exhibit strong migration, invasion, and proliferation abilities. Therefore, exploring the molecular mechanisms of cell fusion can enable us better understand the development of malignant tumors. In this review, the basic process of cell fusion and its significance in cancer is discussed.

Immunolocalization of Fertilin β, IZUMO1, and P34H in Ram Spermatozoa

According to various reports, current methods of sperm freezing destroy the integrity of the sperm plasma membrane and acrosome. This study aimed to determine the changes in the existence and location of three proteins, namely fertilin β, IZUMO1, and P34H, in ram spermatozoa. By using frozen-thawed spermatozoa, ejaculated fresh spermatozoa, and testicular and epididymal spermatozoa (obtained from caput, corpus, and caudal regions), the localizations of the mentioned proteins were performed using signal labeling with indirect immunofluorescence, and the quantification of these proteins was compared using Western blot analyses. Moreover, protein localization and signal labeling in fresh and frozen-thawed spermatozoa subjected to in vitro capacitation and acrosome reaction were compared. Using chlortetracycline (CTC) staining, as expected, it was detected that after incubating for 4 hours under capacitating conditions related to the control sample (0 hour), capacitated and acrosome-reacted sperm were increased (p < 0.001). Frozen-thawed samples had a lower density and expression than the ejaculate samples. Expression was not obtained, except for IZUMO1, from samples that underwent in vitro capacitation/acrosome reactions. Expression of IZUMO1 was seen as an increasing band formation from the equatorial region through the acrosome, after in vitro capacitation. However, after the acrosome reaction, the band formation was only on the equatorial region. Region-specific differences of proteins at the kDa level were obtained using Western blot analysis and possible isoforms specific to ram spermatozoa or proteins with similar epitopes were expressed. Considering the changes in surface proteins in frozen-thawed sperm, it is suggested that fertilin β and P34H can be used as fertility or freezability markers.

Adhesion molecules in gamete transport, fertilization, early embryonic development, and implantation-role in establishing a pregnancy in cattle: A review

Cell-cell adhesion molecules have critically important roles in the early events of reproduction including gamete transport, sperm-oocyte interaction, embryonic development, and implantation. Major adhesion molecules involved in reproduction include cadherins, integrins, and disintegrin and metalloprotease domain-containing (ADAM) proteins. ADAMs on the surface of sperm adhere to integrins on the oocyte in the initial stages of sperm-oocyte interaction and fusion. Cadherins act in early embryos to organize the inner cell mass and trophectoderm. The trophoblast and uterine endometrial epithelium variously express cadherins, integrins, trophinin, and selectin, which achieve apposition and attachment between the elongating conceptus and uterine epithelium before implantation. An overview of the major cell-cell adhesion molecules is presented and this is followed by examples of how adhesion molecules help shape early reproductive events. The argument is made that a deeper understanding of adhesion molecules and reproduction will inform new strategies that improve embryo survival and increase the efficiency of natural mating and assisted breeding in cattle.

Expression dynamics of Integrin Subunit Beta 5 in bovine gametes and embryos imply functions in male fertility and early embryonic development

Integrins have been shown to act as signalling receptors, and they primarily recognise extracellular matrix ligands on the oocyte surface. However, their possible roles in oocyte activation and embryo development are not clearly understood. The objectives of this study were to evaluate expression of Integrin Subunit Beta 5 (ITGβ5) in bovine sperm, oocytes, and early embryos and to ascertain the evolutionary conservation of ITGβ5. To accomplish these objectives, we used western blotting to study expression levels of ITGβ5 protein in sperm and RT-qPCR to determine expression levels of ITGβ5 transcripts in oocytes and embryos. We have also used bioinformatic analysis to determine the evolutionary conservation of the ITGβ5 protein among various species. Western blotting showed that ITGβ5 protein was detectable in bull sperm. Moreover, results of RT-qPCR showed that levels of ITGβ5 were significantly higher in the two-cell embryos, followed by the 8-16-cell embryos. However, no significant difference in expression levels were noted for the morula and blastocyst stages as compared to MII oocytes. Bioinformatic analysis revealed that ITGβ5 is conserved among various species. We conclude that expression of ITGβ5 in bovine gametes and embryos implies an important role in fertilisation and embryogenesis.

Cut loose and run: The complex role of ADAM proteases during neural crest cell development

ADAM metalloproteases have been shown to play critical roles during development. In this review, we will describe functional evidence that implicates ADAM proteins during the genesis, migration and differentiation of neural crest cells. We will restrict our analysis to the transmembrane ADAMs as other reviews have addressed the role of extracellular metalloproteases (Christian et al. [2013] Critical Reviews in Biochemistry and Molecular Biology 48:544-560). This review will describe advances that have been obtained mainly through the use of two vertebrate model systems, the frog, and avian embryos. The role of the principal substrates of ADAMs, the cadherins, has been extensively described in other reviews, most recently in (Cousin [1997] Mechanisms of Development 148:79-88; Taneyhill and Schiffmacher [2017] Genesis, 55). The function of ADAMs in the migration of other cell types, including the immune system, wound healing and cancer has been described previously in (Dreymueller et al. [2017] Mediators of Inflammation 2017: 9621724). Our goal is to illustrate both the importance of ADAMs in controlling neural crest behavior and how neural crest cells have helped us understand the molecular interactions, substrates, and functions of ADAM proteins in vivo.

Overview of transcriptomic analysis of all human proteases, non-proteolytic homologs and inhibitors: Organ, tissue and ovarian cancer cell line expression profiling of the human protease degradome by the CLIP-CHIP™ DNA microarray

The protease degradome is defined as the complete repertoire of proteases and inhibitors, and their nonfunctional homologs present in a cell, tissue or organism at any given time. We review the tissue distribution of virtually the entire degradome in 23 different human tissues and 6 ovarian cancer cell lines. To do so, we developed the CLIP-CHIP™, a custom microarray based on a 70-mer oligonucleotide platform, to specifically profile the transcripts of the entire repertoire of 473 active human proteases, 156 protease inhibitors and 92 non-proteolytically active homologs known at the design date using one specific 70-mer oligonucleotide per transcript. Using the CLIP-CHIP™ we mapped the expression profile of proteases and their inhibitors in 23 different human tissues and 6 ovarian cancer cell lines in 104 sample datasets. Hierarchical cluster analysis showed that expression profiles clustered according to their anatomic locations, cellular composition, physiologic functions, and the germ layer from which they are derived. The human ovarian cancer cell lines cluster according to malignant grade. 110 proteases and 42 inhibitors were tissue specific (1 to 3 tissues). Of these 110 proteases 69% (74) are mainly extracellular, 30% (34) intracellular and 1% intramembrane. Notably, 35% (197/565) of human proteases and 30% (47/156) of inhibitors were ubiquitously expressed in all 23 tissues; 27% (155) of proteases and 21% (32) of inhibitors were broadly expressed in 4-20 tissues. Our datasets provide a valuable resource for the community of baseline protease and inhibitor relative expression in normal human tissues and can be used for comparison with diseased tissue, e.g. ovarian cancer, to decipher pathogenesis, and to aid drug development. This article is part of a Special Issue entitled: Proteolysis as a Regulatory Event in Pathophysiology edited by Stefan Rose-John.

The molecular complexity of fertilization: Introducing the concept of a fertilization synapse

The details of sperm-egg interactions remain a relative mystery despite many decades of research. As new molecular complexities are being discovered, we need to revise the framework in which we think about fertilization. As such, we propose that fertilization involves the formation of a synapse between the sperm and egg. A cellular synapse is a structure that mediates cell adhesion, signaling, and secretion through specialized zones of interaction and polarity. In this review, we draw parallels between the immune synapse and fertilization, and argue that we should consider sperm-egg recognition, binding, and fusion in the context of a "fertilization synapse." Mol. Reprod. Dev. 83: 376-386, 2016. © 2016 Wiley Periodicals, Inc.

The Dark Side of Cell Fusion

Cell fusion is a physiological cellular process essential for fertilization, viral entry, muscle differentiation and placental development, among others. In this review, we will highlight the different cancer cell-cell fusions and the advantages obtained by these fusions. We will specially focus on the acquisition of metastatic features by cancer cells after fusion with bone marrow-derived cells. The mechanism by which cancer cells fuse with other cells has been poorly studied thus far, but the presence in several cancer cells of syncytin, a trophoblastic fusogen, leads us to a cancer cell fusion mechanism similar to the one used by the trophoblasts. The mechanism by which cancer cells perform the cell fusion could be an interesting target for cancer therapy.

Immunotherapy in Multiple Myeloma Using Cancer-Testis Antigens

Context:

Multiple myeloma (MM) is a B-cell malignancy characterized by monoclonal expansion of abnormal plasma cells in the bone marrow. It accounts for 10% of hematological malignancies. Although patients respond to a wide range of anticancer modalities, relapse occurs in a significant number of the cases. Immunotherapeutic approaches have been evolved to tackle this problem. Cancer-testis antigens CTAs as a group of tumor-associated antigens are appropriate targets for cancer immunotherapy as they have restricted expression pattern in normal tissues except for testis which is an immune-privileged site. Expression of these antigens has been assessed in different malignancies including MM.

Evidence Acquisition:

We performed a computerized search of the MEDLINE/PubMed databases with key words: multiple myeloma, cancer-testis antigen, and cancer stem cell and immunotherapy.

Results:

Several CTAs including NY-ESO-1, MAGE and GAGE family have been shown to be expressed in MM patients. Cellular and humoral immune responses against these antigens have been detected in MM patients.

Conclusions:

The frequent and high expression level of CTAs in MM patients shows that these antigens can be applied as cancer biomarkers as well as targets for immunotherapy in these patients.

Sperm-egg fusion: a molecular enigma of mammalian reproduction

The mechanism of gamete fusion remains largely unknown on a molecular level despite its indisputable significance. Only a few of the molecules required for membrane interaction are known, among them IZUMO1, which is present on sperm, tetraspanin CD9, which is present on the egg, and the newly found oolema protein named Juno. A concept of a large multiprotein complex on both membranes forming fusion machinery has recently emerged. The Juno and IZUMO1, up to present, is the only known extracellular receptor pair in the process of fertilization, thus, facilitating the essential binding of gametes. However, neither IZUMO1 nor Juno appears to be the fusogenic protein. At the same time, the tetraspanin is expected to play a role in organizing the egg membrane order and to interact laterally with other factors. This review summarizes, to present, the known molecules involved in the process of sperm-egg fusion. The complexity and expected redundancy of the involved factors makes the process an intricate and still poorly understood mechanism, which is difficult to comprehend in its full distinction.

A microarray-based analysis of gametogenesis in two Portuguese populations of the European clam Ruditapes decussatus

The European clam, Ruditapes decussatus is a species with a high commercial importance in Portugal and other Southern European countries. Its production is almost exclusively based on natural recruitment, which is subject to high annual fluctuations. Increased knowledge of the natural reproductive cycle of R. decussatus and its molecular mechanisms would be particularly important in providing new highly valuable genomic information for better understanding the regulation of reproduction in this economically important aquaculture species. In this study, the transcriptomic bases of R. decussatus reproduction have been analysed using a custom oligonucleotide microarray representing 51,678 assembled contigs. Microarray analyses were performed in four gonadal maturation stages from two different Portuguese wild populations, characterized by different responses to spawning induction when used as progenitors in hatchery. A comparison between the two populations elucidated a specific pathway involved in the recognition signals and binding between the oocyte and components of the sperm plasma membrane. We suggest that this pathway can explain part of the differences in terms of spawning induction success between the two populations. In addition, sexes and reproductive stages were compared and a correlation between mRNA levels and gonadal area was investigated. The lists of differentially expressed genes revealed that sex explains most of the variance in gonadal gene expression. Additionally, genes like Foxl2, vitellogenin, condensing 2, mitotic apparatus protein p62, Cep57, sperm associated antigens 6, 16 and 17, motile sperm domain containing protein 2, sperm surface protein Sp17, sperm flagellar proteins 1 and 2 and dpy-30, were identified as being correlated with the gonad area and therefore supposedly with the number and/or the size of the gametes produced.

Helping Eve overcome ADAM: G-quadruplexes in the ADAM-15 promoter as new molecular targets for breast cancer therapeutics

ADAM-15, with known zymogen, secretase, and disintegrin activities, is a catalytically active member of the ADAM family normally expressed in early embryonic development and aberrantly expressed in various cancers, including breast, prostate and lung. ADAM-15 promotes extracellular shedding of E-cadherin, a soluble ligand for the HER2/neu receptor, leading to activation, increased motility, and proliferation. Targeted downregulation of both ADAM-15 and HER2/neu function synergistically kills breast cancer cells, but to date there are no therapeutic options for decreasing ADAM-15 function or expression. In this vein, we have examined a unique string of guanine-rich DNA within the critical core promoter of ADAM-15. This region of DNA consists of seven contiguous runs of three or more consecutive guanines, which, under superhelical stress, can relax from duplex DNA to form an intrastrand secondary G-quadruplex (G4) structure. Using biophysical and biological techniques, we have examined the G4 formation within the entire and various truncated regions of the ADAM-15 promoter, and demonstrate strong intrastrand G4 formation serving to function as a biological silencer element. Characterization of the predominant G4 species formed within the ADAM-15 promoter will allow for specific drug targeting and stabilization, and the further development of novel, targeted therapeutics.

A transgenic insertion on mouse chromosome 17 inactivates a novel immunoglobulin superfamily gene potentially involved in sperm-egg fusion

Fertilization is the process that leads to the formation of a diploid zygote from two haploid gametes. This is achieved through a complex series of cell-to-cell interactions between a sperm and an egg. The final event of fertilization is the fusion of the gametes' membranes, which allows the delivery of the sperm genetic material into the egg cytoplasm. In vivo studies in the laboratory mouse have led to the discovery of membrane proteins that are essential for the fusion process in both the sperm and egg. Specifically, the sperm protein Izumo1 was shown to be necessary for normal fertility. Izumo1-deficient spermatozoa fail to fuse with the egg plasma membrane. Izumo1 is a member of the Immunoglobulin Superfamily of proteins, which are known to be involved in cell adhesion. Here, we describe BART97b, a new mouse line with a recessive mutation that displays a fertilization block associated with a failure of sperm fusion. BART97b mutants carry a deletion that inactivates Spaca6, a previously uncharacterized gene expressed in testis. Similar to Izumo1, Spaca6 encodes an immunoglobulin-like protein. We propose that the Spaca6 gene product may, together with Izumo1, mediate sperm fusion by binding an as yet unidentified egg membrane receptor.

Critical role of exosomes in sperm-egg fusion and virus-induced cell-cell fusion

In mammals, two integral membrane proteins, sperm IZUMO1 and egg CD9, regulate sperm-egg fusion, and their roles are critical, but yet unclear. Recent studies, however, indicate interesting connections between the sperm-egg fusion and virus-induced cell-cell fusion. First, CD9-containing exosome-like vesicles, which are released from wild-type eggs, can induce the fusion between sperm and CD9-deficient egg, even though CD9-deficient eggs are highly refractory to the fusion with sperm. This finding provides strong evidence for the involvement of CD9-containing, fusion-facilitating vesicles in the sperm-egg fusion. Secondly, there are similarities between the generation of retroviruses in the host cells and the formation of small cellular vesicles, termed exosomes, in mammalian cells. The exosomes are involved in intercellular communication through transfer of proteins and ribonucleic acids (RNAs) including mRNAs and microRNAs. These collective studies provide an insight into the molecular mechanism of membrane fusion events.

Inhibitors of zinc-dependent metalloproteases hinder sperm passage through the cumulus oophorus during porcine fertilization in vitro

In this study, we report for the first time on a possible contribution of metalloproteases in sperm passage through the cumulus matrix in pigs. The presence of 20 μM 1,10-phenanthroline (1,10-PHEN), inhibitor of zinc-dependent metalloproteases, strongly inhibited the degree of sperm penetration in cumulus-intact (CI), but not in cumulus-free (CF), porcine oocytes during IVF. The inhibitory effect of 1,10-PHEN was due to the chelation of metal ions as a non-chelating analog (1,7-PHEN) did not affect IVF rates. Furthermore, incubation with 1,10-PHEN did not affect sperm binding to the zona pellucida nor sperm motility, membrane integrity, or acrosomal status. These findings led to the assumption that 1,10-PHEN interacts with a sperm- or cumulus-derived metalloprotease. Metalloproteases are key players in physiological processes involving degradation or remodeling of extracellular matrix. In vivo, their proteolytic activity is regulated by tissue inhibitors of metalloproteases (TIMP1-TIMP4). We tested the effect of TIMP3 on fertilization parameters after porcine IVF. Similar to 1,10-PHEN, TIMP3 inhibited total fertilization rate of CI but not CF oocytes and did not influence sperm quality parameters. Although the inhibitory effect was stronger in CI oocytes, TIMP3 also reduced the degree of sperm penetration in CF oocytes, suggesting the involvement of a metalloprotease in a subsequent step during fertilization. In conclusion, our results indicate the involvement of TIMP3-sensitive, zinc-dependent metalloprotease activity in sperm passage through the cumulus oophorus in pigs. The results should provide the basis for further biochemical research toward the localization and identification of the metalloprotease involved.

Sperm surface changes and physiological consequences induced by sperm handling and storage

Spermatozoa interact with their immediate environment and this contact remodels the sperm surface in preparation for fertilisation. These fundamental membrane changes will be critically covered in this review with special emphasis on the very specific surface destabilisation event, capacitation. This process involves very subtle and intricate modifications of the sperm membrane including removal of suppression (decapacitation) factors and changes in the lateral organisation of the proteins and lipids of the sperm surface. Processing of sperm for assisted reproduction (storage, sex-sorting, etc.) subjects spermatozoa to numerous stressors, and it is possible that this processing overrides such delicate processes resulting in sperm instability and cell damage. To improve sperm quality, novel mechanisms must be used to stabilise the sperm surface during handling. In this review, different types of membrane stress are considered, as well as novel surface manipulation methods to improve sperm stability.

Synergistic Regulation of Angiogenic Sprouting by Biochemical Factors and Wall Shear Stress

The process of sprouting angiogenesis involves activating endothelial cells in a quiescent monolayer of an existing vessel to degrade and migrate into the underlying matrix to form new blood vessels. While the roles of biochemical factors in angiogenic sprouting have been well characterized, the roles of fluid forces have received much less attention. This review summarizes results that support a role for wall shear stress in post-capillary venules as a mechanical factor capable of synergizing with biochemical factors to stimulate pro-angiogenic signaling in endothelial cells and promote sprout formation.

The emerging role of matrix metalloproteases of the ADAM family in male germ cell apoptosis

Constitutive germ cell apoptosis during mammalian spermatogenesis is a key process for controlling sperm output and to eliminate damaged or unwanted cells. An increase or decrease in the apoptosis rate has deleterious consequences and leads to low sperm production. Apoptosis in spermatogenesis has been widely studied, but the mechanism by which it is induced under physiological or pathological conditions has not been clarified. We have recently identified the metalloprotease ADAM17 (TACE) as a putative physiological inducer of germ cell apoptosis. The mechanisms involved in regulating the shedding of the ADAM17 extracellular domain are still far from being understood, although they are important in order to understand cell-cell communications. Here, we review the available data regarding apoptosis during mammalian spermatogenesis and the localization of ADAM proteins in the male reproductive tract. We propose an integrative working model where ADAM17, p38 MAPK, protein kinase C (PKC) and the tyrosine kinase c-Abl participate in the physiological signalling cascade inducing apoptosis in germ cells. In our model, we also propose a role for the Sertoli cell in regulating the Fas/FasL system in order to induce the extrinsic pathway of apoptosis in germ cells. This working model could be applied to further understand constitutive apoptosis in spermatogenesis and in pathological conditions (e.g., varicocele) or following environmental toxicants exposure (e.g., genotoxicity or xenoestrogens).

Cancer-germline antigen vaccines and epigenetic enhancers: future strategies for cancer treatment

IMPORTANCE OF THE FIELD

Immunotherapy holds great potential for disseminated cancer, and cancer-germline (CG) antigens are among the most promising tumor targets. They are widely expressed in different cancer types and are essentially tumor-specific, since their expression in normal tissues is largely restricted to immune-privileged sites. Although the therapeutic potential of these antigens may be compromised by their highly heterogeneous expression in many tumors and low frequency in some cancers, recent developments suggest that tumor-cell-selective enhancement of CG antigen gene expression can be achieved using epigenetic modifiers.

AREAS COVERED IN THIS REVIEW

We provide an overview of the potential of CG antigens as targets for cancer immunotherapy, including advantages and disadvantages. We also discuss the current state of development of CG antigen vaccines, and the potential synergistic effect of combining CG antigen immunotherapeutic strategies with epigenetic modifiers.

WHAT THE READER WILL GAIN

The reader will gain an overview of the past, present and future role of CG antigens in cancer immunotherapy.

TAKE HOME MESSAGE

Chemoimmunotherapy using epigenetic drugs and CG antigen vaccines may be a useful approach for treating cancer.

Sexual selection and the molecular evolution of ADAM proteins

Rapid evolution has been identified for many reproductive genes and recent studies have combined phylogenetic tests and information on species mating systems to test sexual selection. Here we examined the molecular evolution of the ADAM gene family, a diverse group of 35 proteins capable of adhesion to and cleavage of other proteins, using sequence data from 25 mammalian genes. Out of the 25 genes analyzed, all those expressed in male reproductive tissue showed evidence of positive selection. Positively selected amino acids within the protein adhesion domain were only found in sperm surface ADAM proteins (ADAMs 1, 2, 3, 4, and 32) suggesting selection driven by male x female interactions. We tested heterogeneity in rates of evolution of the adhesion domain of ADAM proteins by using sequence data from Hominidae and macaques. The use of the branch and branch-site models (PAML) showed evidence of higher d (N)/d (S) and/or positive selection linked to branches experiencing high postmating selective pressures (chimpanzee and macaque) for Adams 2, 18, and 23. Moreover, we found consistent higher proportion of nonsynonymous relative to synonymous and noncoding sequence substitutions in chimpanzee and/or macaque only for Adams 2, 18, and 23. Our results suggest that lineage-specific sexual selection bouts might have driven the evolution of the adhesion sperm protein surface domains of ADAMs 2 and 18 in primates. Adams 2 and 18 are localized in chromosome 8 of primates and adjacent to each other, so their evolution might have also been influenced by their common genome localization.

Involvement of ADAMs in tumorigenesis and progression of hepatocellular carcinoma: Is it merely fortuitous or a real pathogenic link?

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and one of the most frequent types of cancer worldwide. It normally develops in patients with chronic liver disease, especially cirrhosis, although some cases without an apparent underlying liver disease have been reported. The pathogenesis of HCC is multi-factorial and complex. Hepatitis viruses are the main factors favoring the development of HCC. In fact, chronic inflammation associated with hepatitis C or B virus infection can lead to progressive liver fibrosis, cirrhosis and ultimately HCC. Chronic inflammation and liver fibrosis cause a continuous remodeling of the extracellular matrix (ECM), a dynamic process that involves several molecules including integrins and matrix processing enzymes. An increasing body of evidence indicates that ADAMs are involved in promoting tumor formation and progression of HCC. A Disintegrin And Metalloproteases (ADAMs) are a group of proteins belonging to the zinc protease superfamily. ADAMs are usually transmembrane proteins that contain disintegrin and metalloprotease domains and are, therefore, able to carry out both cell adhesion and protease activities. Soluble isoforms of ADAMs have also been discovered and characterized. In this review, we focus on the contribution of ADAM proteins to HCC tumorigenesis and cancer progression. The potential role of ADAMs as key modulators of tumor-stroma interactions during tumor progression, by means of the activities of their constituent domains, is also discussed.

Role of ADAM and ADAMTS metalloproteinases in airway diseases

Lungs are exposed to the outside environment and therefore to toxic and infectious agents or allergens. This may lead to permanent activation of innate immune response elements. A Disintegrin And Metalloproteinases (ADAMs) and ADAMs with Thrombospondin motifs (ADAMTS) are proteinases closely related to Matrix Metalloproteinases (MMPs). These multifaceted molecules bear metalloproteinase and disintegrin domains endowing them with features of both proteinases and adhesion molecules. Proteinases of the ADAM family are associated to various physiological and pathological processes and display a wide spectrum of biological effects encompassing cell fusion, cell adhesion, "shedding process", cleavage of various substrates from the extracellular matrix, growth factors or cytokines... This review will focus on the putative roles of ADAM/ADAMTS proteinases in airway diseases such as asthma and COPD.

The transcriptome of spermatozoa used in homologous intrauterine insemination varies considerably between samples that achieve pregnancy and those that do not

OBJECTIVE

To differentiate transcripts' expression in the sperm from patients who achieved pregnancy in their first IUI cycle from those who did not. Basic sperm analysis is limited to forecasting pregnancies by means of assisted reproduction. New assays, such as microarray analysis, are potential predictive tools for this purpose.

DESIGN

Nested case-control study.

SETTING

University-affiliated private setting.

PATIENT(S)

Twenty sperm samples were obtained from infertile males undergoing their first IUI cycle with healthy partners. Sperm samples with which pregnancy was achieved (P; n=10) and those with which it was not achieved (NP; n=10) were identified and their respective messenger RNA expression profiles were compared.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Using microarrays, global genome expression was compared in pooled samples from each group. Results were evaluated to detect differentially expressed transcripts (TDEs; FC>2; P<0.05) and to identify those transcripts that were expressed in only one of the groups (exclusive transcripts [ETs]).

RESULT(S)

In group P, 756 TDEs presented increased expression, whereas 194 in group NP were found to be overexpressed. Furthermore, we found 741 ETs that were expressed only in group P and 976 that were expressed only in group NP.

CONCLUSION(S)

Results reveal profound differences between expression profiles of sperm samples that impregnate successfully and those that do not. These differences might improve the predictive power of sperm evaluation to estimate IUI success by complementing the basic sperm analysis.

The podosomal-adaptor protein SH3PXD2B is essential for normal postnatal development

Podosome-type adhesions are actin-based membrane protrusions involved in cell-matrix adhesion and extracellular matrix degradation. Despite growing knowledge of many proteins associated with podosome-type adhesions, much remains unknown concerning the function of podosomal proteins at the level of the whole animal. In this study, the spontaneous mouse mutant nee was used to identify a component of podosome-type adhesions that is essential for normal postnatal growth and development. Mice homozygous for the nee allele exhibited runted growth, craniofacial and skeletal abnormalities, ocular anterior segment dysgenesis, and hearing impairment. Adults also exhibited infertility and a form of lipodystrophy. Using genetic mapping and DNA sequencing, the cause of nee phenotypes was identified as a 1-bp deletion within the Sh3pxd2b gene on mouse Chromosome 11. Whereas the wild-type Sh3pxd2b gene is predicted to encode a protein with one PX domain and four SH3 domains, the nee mutation is predicted to cause a frameshift and a protein truncation altering a portion of the third SH3 domain and deleting all of the fourth SH3 domain. The SH3PXD2B protein is believed to be an important component of podosomes likely to mediate protein-protein interactions with membrane-spanning metalloproteinases. Testing this directly, SH3PXD2B localized to podosomes in constitutively active Src-transfected fibroblasts and through its last SH3 domain associated with a transmembrane member of a disintegrin and metalloproteinase family of proteins, ADAM15. These results identify SH3PXD2B as a podosomal-adaptor protein required for postnatal growth and development, particularly within physiologic contexts involving extracellular matrix regulation.

ADAM17 co-purifies with TIMP-3 and modulates endothelial invasion responses in three-dimensional collagen matrices

In this study, we investigated potential mechanisms through which the known anti-angiogenic factor, tissue inhibitor of metalloproteinase-3 (TIMP-3) blocks angiogenesis. As a strategy to identify TIMP-3 binding proteins, we used tandem affinity purification, employing recombinant adenoviruses constructed to deliver TIMP-3 fused to C-terminal S and His tags (TIMP-3-S-His) or TIMP-1-S-His control to endothelial cells prior to extraction. Western blotting of final eluates revealed robust binding of A Disintegrin and Metalloproteinase (ADAM) 17 and a slight association of ADAM15 to TIMP-3, but not TIMP-1 control. To confirm a functional requirement for ADAM15 and 17 in mediating angiogenic events, a model of endothelial cell invasion was utilized. Silencing of ADAM17, but not ADAM15, expression using small interfering RNA (siRNA) interfered with invasion, resulting in decreased density of invading cells and decreased invasion distance. Stable EC lines expressing short hairpin RNA directed to ADAM17 were similarly inhibited. To confirm these results, dominant negative mutants (DeltaMPs) of ADAM10, ADAM15 or ADAM17 were delivered using recombinant lentiviruses. Expression of ADAM17 DeltaMP, but not ADAM10 or ADAM15 DeltaMP, decreased invasion density and distance. Further, time-lapse analyses revealed ADAM17 DeltaMP cells exhibited far greater numbers of protruding sprouts compared to control, suggesting an inability of extended processes to retract properly. Immunofluorescence analyses revealed ADAM17 localized to bifurcations in invading sprouts. These data jointly indicate a role for ADAM17 in modulating endothelial sprouting events during angiogenesis.

Influence of ADAM28 on biological characteristics of human dental follicle cells

OBJECTIVES

The aim of this study was to investigate the effects of a disintegrin and metalloproteinase 28 (ADAM28) on the biological characteristics of human dental follicle cells (HDFCs) and possible action mechanism.

METHODS

Eukaryotic expression plasmid containing ADAM28 coding region and ADAM28 antisense oligodeoxynucleotides (AS-ODN) with FITC labelling were constructed and synthesised by gene clone and recombination. Then we respectively transfected them into HDFCs by Lipofectamine 2000 system and detected their effects on proliferation, differentiation and apoptosis of HDFCs by MTT assay, cell cycle detection, ALP activity and Annexin V-FITC/PI analysis. Finally we observed the effects of ADAM28 AS-ODN on HDFCs expressing extracellular matrix (ECM) proteins by immunocytochemical staining.

RESULTS

ADAM28 eukaryotic plasmid was constructed and identified successfully, and could be correctly translated and expressed in HDFCs, furthermore overexpression of ADAM28 promoted the HDFCs proliferation and inhibited specific differentiation of HDFCs, while inhibition of ADAM28 exerted the opposite effects and induced apoptosis. Moreover ADAM28 could significantly inhibit the secretion of OPN and type III collagen of HDFCs.

CONCLUSIONS

ADAM28 might actively participate in the network regulation which associates HDFCs proliferation, differentiation, apoptosis with matrix mineralisation during tooth development by interacting with multiple signal molecules.

Beta1 integrin is an adhesion protein for sperm binding to eggs

We investigated the role of beta(1) integrin in mammalian fertilization and the mode of inhibition of fertilinbeta-derived polymers. We determined that polymers displaying the Glu-Cys-Asp peptide from the fertilinbeta disintegrin domain mediate inhibition of mammalian fertilization through a beta(1) integrin receptor on the egg surface. Inhibition of fertilization is a consequence of competition with sperm binding to the cell surface, not activation of an egg-signaling pathway. The presence of the beta(1) integrin on the egg surface increases the rate of sperm attachment but does not alter the total number of sperm that can attach or fuse to the egg. We conclude that the presence of beta(1) integrin enhances the initial adhesion of sperm to the egg plasma membrane and that subsequent attachment and fusion are mediated by additional egg and sperm proteins present in the beta(1) integrin complex. Therefore, the mechanisms by which sperm fertilize wild-type and beta(1) knockout eggs are different.

Polymeric ADAM protein mimics interrogate mammalian sperm-egg binding

The sperm proteins ADAM2 and ADAM3, members of the ADAM family of proteins, have been implicated in mammalian sperm-egg binding. However, elucidating their roles is complex because of the interdependence of ADAM protein expression in the testis. Hence, multivalent probes containing the three-amino acid binding sequence of ADAM2, glutamate-cysteine-aspartate (ECD), and ADAM3, glutamine-cysteine-aspartate (QCD), were designed, synthesized, and tested to investigate gamete interactions. In this work, ECD polymer mimics were synthesized by ring-opening metathesis polymerization with a faster initiating ruthenium catalyst than previously used. Polymers containing 100 copies of the ECD peptide mimic were found to be the best inhibitors of fertilization. The multivalent QCD polymers were also tested as inhibitors of fertilization. The structure-activity profile was the same as ECD polymers, but the overall potency was lower. Both ECD and QCD polymers require the presence of beta(1) integrin to inhibit fertilization. Next, triblock ABA and ABC copolymers containing both ECD and QCD ligands were synthesized with 96 monomer spacers as their B blocks. Although these polymers had lower densities of ECD and QCD peptides, their potencies correlated with the potencies of their corresponding homopolymers. In addition, no synergy between ECD and QCD mimics was observed. All the data suggest that QCD and ECD bind to the same complex of proteins that includes beta(1) integrin.

The ADAM metalloproteinases

The ADAMs (a disintegrin and metalloproteinase) are a fascinating family of transmembrane and secreted proteins with important roles in regulating cell phenotype via their effects on cell adhesion, migration, proteolysis and signalling. Though all ADAMs contain metalloproteinase domains, in humans only 13 of the 21 genes in the family encode functional proteases, indicating that at least for the other eight members, protein–protein interactions are critical aspects of their biological functions. The functional ADAM metalloproteinases are involved in “ectodomain shedding” of diverse growth factors, cytokines, receptors and adhesion molecules. The archetypal activity is shown by ADAM-17 (tumour necrosis factor-α convertase, TACE), which is the principal protease involved in the activation of pro-TNF-α, but whose sheddase functions cover a broad range of cell surface molecules. In particular, ADAM-17 is required for generation of the active forms of Epidermal Growth Factor Receptor (EGFR) ligands, and its function is essential for the development of epithelial tissues. Several other ADAMs have important sheddase functions in particular tissue contexts. Another major family member, ADAM-10, is a principal player in signalling via the Notch and Eph/ephrin pathways. For a growing number of substrates, foremost among them being Notch, cleavage by ADAM sheddases is essential for their subsequent “regulated intramembrane proteolysis” (RIP), which generates cleaved intracellular domains that translocate to the nucleus and regulate gene transcription. Several ADAMs play roles in spermatogenesis and sperm function, potentially by effecting maturation of sperm and their adhesion and migration in the uterus. Other non-catalytic ADAMs function in the CNS via effects on guidance mechanisms. The ADAM family are thus fundamental to many control processes in development and homeostasis, and unsurprisingly they are also linked to pathological states when their functions are dysregulated, including cancer, cardiovascular disease, asthma, Alzheimer’s disease. This review will provide an overview of current knowledge of the human ADAMs, discussing their structure, function, regulation and disease involvement.

Presence, processing, and localization of mouse ADAM15 during sperm maturation and the role of its disintegrin domain during sperm–egg binding

Successful fertilization requires gametes to complete several stages, beginning with maturation and transport along the male and female reproductive tracts and ending with the interaction between the sperm and the egg. This last step involves sperm–egg adhesion and membrane fusion. ADAMs (disintegrin and metalloprotease domain proteins) are a family of membrane-anchored glycoproteins that are thought to play diverse roles in cell–cell adhesion through their interaction with integrins. This study analyzes the presence, location, processing, and possible role of ADAM15 in mouse sperm. The presence of ADAM15 in mouse spermatozoa was detected by Western blotting, which revealed that ADAM15 is post-translationally processed, during epididymal sperm maturation and the acrosome reaction. The 35 kDa antigen present in the acrosome-reacted sperm is the last proteolytic product of the 110/75 kDa ADAM15 found in non-capacitated sperm. This 35 kDa protein contains the disintegrin domain. By indirect immunofluorescence, ADAM15 was identified in the acrosomal region and along the flagellum of mouse spermatozoa. In acrosome-reacted sperm, ADAM15 was lost from the acrosomal region, but remained diffusely distributed throughout the head and flagellum. Furthermore, the ADAM15 disintegrin domain (RPPTDDCDLPEF) partially inhibited fusion and almost completely inhibited sperm–oolemma adhesion. In conclusion, our data indicate that ADAM15 is present in the testis and in spermatozoa from the caput, corpus, and cauda epididymis, as well as in non-capacitated and acrosome-reacted gametes. Results also indicate that ADAM15 is processed during epididymal maturation and acrosome reaction and that it may play a role during sperm–egg binding.

Anchoring junctions as drug targets: role in contraceptive development

In multicellular organisms, cell-cell interactions are mediated in part by cell junctions, which underlie tissue architecture. Throughout spermatogenesis, for instance, preleptotene leptotene spermatocytes residing in the basal compartment of the seminiferous epithelium must traverse the blood-testis barrier to enter the adluminal compartment for continued development. At the same time, germ cells must also remain attached to Sertoli cells, and numerous studies have reported extensive restructuring at the Sertoli-Sertoli and Sertoli-germ cell interface during germ cell movement across the seminiferous epithelium. Furthermore, the proteins and signaling cascades that regulate adhesion between testicular cells have been largely delineated. These findings have unveiled a number of potential "druggable" targets that can be used to induce premature release of germ cells from the seminiferous epithelium, resulting in transient infertility. Herein, we discuss a novel approach with the aim of developing a nonhormonal male contraceptive for future human use, one that involves perturbing adhesion between Sertoli and germ cells in the testis.

Inhibition of alpha(4) integrin mediated adhesion was involved in the reduction of B16-F10 melanoma cells lung colonization in C57BL/6 mice treated with gambogic acid

Gambogic acid, the major active ingredient of gamboge, has been shown to exhibit anti-cancer activity both in vivo and in vitro. However, its potential activity in tumor metastasis remains unclear. In the present study, we found that gambogic acid strongly inhibited the adhesion of highly metastatic mouse melanoma B16-F10 cells in vitro. Gambogic acid also exhibited significant anti-metastasis activity on the development of in vivo artificial metastases (i.e. following tail vein i.v. injection of the B16-F10 melanoma tumor cells in C57BL/6 mice). Flow cytometric analysis and Western blot showed that gambogic acid inhibited the cell surface expression of alpha(4) integrin, while exhibited negligible effects on the expression of alpha(5) and beta(1) integrin. Thus we concluded for the first time that gambogic acid could inhibit the adhesion and migration of B16-F10 cells in vitro and in vivo, in which down-regulation of alpha(4) integrin expression was involved.

Leukocyte cell surface proteinases: regulation of expression, functions, and mechanisms of surface localization

A number of proteinases are expressed on the surface of leukocytes including members of the serine, metallo-, and cysteine proteinase superfamilies. Some proteinases are anchored to the plasma membrane of leukocytes by a transmembrane domain or a glycosyl phosphatidyl inositol (GPI) anchor. Other proteinases bind with high affinity to classical receptors, or with lower affinity to integrins, proteoglycans, or other leukocyte surface molecules. Leukocyte surface levels of proteinases are regulated by: (1) cytokines, chemokines, bacterial products, and growth factors which stimulate synthesis and/or release of proteinases by cells; (2) the availability of surface binding sites for proteinases; and/or (3) internalization or shedding of surface-bound proteinases. The binding of proteinases to leukocyte surfaces serves many functions including: (1) concentrating the activity of proteinases to the immediate pericellular environment; (2) facilitating pro-enzyme activation; (3) increasing proteinase stability and retention in the extracellular space; (4) regulating leukocyte function by proteinases signaling through cell surface binding sites or other surface proteins; and (5) protecting proteinases from inhibition by extracellular proteinase inhibitors. There is strong evidence that membrane-associated proteinases on leukocytes play critical roles in wound healing, inflammation, extracellular matrix remodeling, fibrinolysis, and coagulation. This review will outline the biology of membrane-associated proteinases expressed by leukocytes and their roles in physiologic and pathologic processes.

Isolation and characterization of alpha1-proteinase inhibitor from common carp (Cyprinus carpio) seminal plasma

Using a three-step procedure, we purified (79 and 51.6-fold to homogeneity) and characterized the two isoforms (a and b) of alpha1-proteinase inhibitor-like protein from carp seminal plasma. The isoforms have molecular masses of 55.5 and 54.0 kDa, respectively. These inhibitors formed SDS-stable complexes with cod and bovine trypsin, chymotrypsin and elastase. The thirty-three amino acids within the reactive loop SLPDTVILNRPFLVLIVEDTTKSILFMGKITNP were identified for isoform b. The same first ten amino acids were obtained for isoform a, and this sequence revealed 100% homology to carp alpha1-proteinase inhibitor (alpha1-PI) from perimeningeal fluid. Both isoforms of alpha1-PI are glycoproteins and their carbohydrate content was determined to be 12.6 and 12.1% for a and b, respectively. Our results indicated that alpha1-PI is one of the main proteins of carp seminal plasma. Using polyclonal anti-alpha1-PI antibodies, alpha1-PI was for the first time localized to the carp testis. The presence of alpha1-PI in testis lobules and in the area surrounding spermatides suggests that this inhibitor may be involved in the maintenance of testis connective tissue integrity, control of spermatogenesis or protection of tissue and spermatozoa against unwanted proteolysis. Since similar alpha1-PI has been identified in rainbow trout semen it can be suggested that the presence of alpha1-PI in seminal plasma is a common feature of cyprinid and salmonid fish.

ADAM proteins in the brain

ADAM proteins are a family of metalloproteinases with a disintegrin domain. They have proteolytic as well as adhesive functions and can be involved in cell fusion events. Some ADAM proteins are expressed in a highly tissue restricted fashion, whereas others are expressed quite ubiquitously. In the brain, ADAM proteins have a role in neural development, axon guidance and inflammatory responses. Although there may be some functional overlap, homozygous deletion of some ADAM genes in mice can have fatal consequences. The expression and possible role of ADAM proteins in the brain will be discussed.

Multiple proteins present in purified porcine sperm apical plasma membranes interact with the zona pellucida of the oocyte

An important step in fertilization is the recognition and primary binding of the sperm cell to the zona pellucida (ZP). Primary ZP binding proteins are located at the apical plasma membrane of the sperm head. In order to exclusively study primary zona binding proteins, plasma membranes of sperm heads were isolated, highly purified and subsequently solubilized with a mild or a strong solubilization procedure. Native, highly purified ZP ghosts were used as the binding substrate for solubilized sperm plasma membrane proteins, and a proteomic approach was employed to identify ZP binding proteins. Two-dimensional gel electrophoresis of ZP fragments with bound sperm proteins showed very reproducibly 24 sperm protein spots to be associated to the zona ghosts after mild plasma membrane solubilization whereas only three protein spots were detected after strong plasma membrane solubilization. This indicates the involvement of multiple sperm proteins in ZP binding. The three persistently bound proteins were identified by a tandem mass spectrometry as isoforms of AQN-3 and probably represent the main sperm protein involved in ZP binding. P47, fertilin beta and peroxiredoxin 5 were also conclusively identified. None of the identified proteins has a known acrosomal origin, which further indicated that there was no sample contamination with secondary ZP binding proteins from the acrosomal matrix. In this study, we showed and identified multiple zona binding proteins involved in primary sperm-zona binding. Although we were not able to identify all of the proteins involved, this is a first step in understanding the event of primary sperm-zona interactions and the relevance of this for fertilization is discussed.

Detection of osteopontin on Holstein bull spermatozoa, in cauda epididymal fluid and testis homogenates, and its potential role in bovine fertilization

Osteopontin (OPN) is a secreted extracellular matrix phosphoprotein identified in various tissues and fluids including those of the male and female reproductive tracts. OPN was previously identified as a 55 kDa high fertility marker in Holstein bull seminal plasma, produced by the ampulla and the vesicular gland. The objectives of this study were to characterize OPN on ejaculated and cauda epididymal sperm using immunofluorescence and western blot analysis, and to assess the role of sperm OPN in fertilization. Solubilized sperm membrane proteins from ejaculated and cauda epididymal sperm were separated by 1D SDS-PAGE, transferred to nitrocellulose, and probed with an antibody to bovine milk OPN. A 35 kDa protein was detected by this antibody in both ejaculated and cauda epididymal sperm membranes. Analyses also recognized OPN at 55 and 25 kDa in cauda epididymal fluid and testicular parenchyma homogenates respectively. Immunofluorescent analysis of ejaculated and cauda epididymal sperm showed OPN localization in a well-defined band in the postacrosomal region of the sperm head and also on the midpiece. Results ofin vitrofertilization experiments showed that sperm treated with an antibody to OPN fertilized fewer oocytes than sperm treated with control medium while increasing incidence of polyspermy, suggesting a role of sperm-associated OPN in fertilization and a block to polyspermy. These studies demonstrate that OPN exists at multiple molecular weight forms in the bull reproductive tract and its presence on ejaculated sperm may signal its importance in fertilization by interacting with integrins or other proteins on the oocyte plasma membrane.

Enigmas of mammalian gamete form and function

The gametes of man and some other Eutheria have been manipulated successfully for practical reasons, but many gaps remain in our basic understanding of the way that they function. This situation stems not least from a failure to recognize the extent to which eutherian spermatozoa and eggs, and elements related to their operation, have come to differ from those of other groups. Novel features in the male that reflect this include a radical design of the sperm head with the acrosome seeming to function primarily in egg-coat binding rather than its lysis, a multifaceted post-testicular sperm maturation and an androgen/low-temperature-regulated system of sperm storage--both tied to the epididymis, a variable male accessory sex gland complex, and descent of the testis and epididymis to a scrotum. In the female, such novelties are represented in a need for sperm capacitation, in an unusual regulation of sperm transport within the oviduct, in the cumulus oophorus and character of the zona pellucida around the small egg, and in a unique configuration of gamete fusion. The collective evidence now suggests that many of these features reflect a new fertilisation strategy or its consequences, with most being causally linked. One initial 'domino' in this regard appears to be the small yolkless state of the egg and its intolerance for polyspermy, as determinants of the unusual mode of oviductal sperm transport and possibly the existence and form of the cumulus oophorus. However, a particularly influential first 'domino' appears to be the physical character of the eutherian zona pellucida. This differs from the egg coats of other animal groups by virtue of a resilient elasticity and thickness. These qualities allow this primary and often only coat to stretch and so persist during later expansion of the blastocyst, usually until close to implantation. At the same time, the dimensions, physical character, and particularly the relative protease-insensitivity of the zona appear to have had profound effects on sperm form and function and, more indirectly, on sperm-related events in the male and the female tract. Marsupials display some similarities and also some strikingly different features, against which the enigmas of the eutherian situation can be evaluated.

Cell-surface association between matrix metalloproteinases and integrins: role of the complexes in leukocyte migration and cancer progression

Leukocyte motility is known to be dependent on both β2-integrins and matrix metalloproteinases MMP-2/-9 or gelatinases, which mediate leukocyte adhesion and the proteolysis needed for invasion, respectively. Gelatinases not only play an important role in cell migration, tissue remodeling, and angiogenesis during development, but are also involved in the progression and invasiveness of many cancers, including leukemias. The concept that MMPs associate with integrins, as well as their importance in some physiologic and pathologic conditions, has been advanced previously but has not been examined on leukocytes. This review will examine mainly the function of the MMP-integrin complexes in normal leukocyte migration and the effect of integrin and broad-spectrum MMP inhibitors in tumor progression.

Efficient ADAM22 surface expression is mediated by phosphorylation-dependent interaction with 14-3-3 protein family members

ADAM22 is one of three catalytically inactive ADAM family members highly expressed in the brain. ADAM22 has numerous splice variants, all with considerable cytoplasmic tails of up to 148 amino acids. ADAM22 can act to inhibit cell proliferation, however, it has been suggested that it also acts as an adhesion protein. We identified three 14-3-3 protein members by a yeast two-hybrid screen and show by co-immunoprecipitation that the cytoplasmic domain of ADAM22 can interact with all six 14-3-3 proteins expressed in the brain. In addition, we show that 14-3-3 proteins interact preferentially with the serine phosphorylated precursor form of ADAM22. ADAM22 has two 14-3-3 protein binding consensus motifs; the first binding site, spanning residues 831-834, was shown to be the most crucial for 14-3-3 binding to occur. The interaction between ADAM22 and 14-3-3 proteins is dependent on phosphorylation of ADAM22, but not of 14-3-3 proteins. ADAM22 point mutants lacking functional 14-3-3 protein binding motifs could no longer accumulate efficiently at the cell surface. Deletion of both 14-3-3 binding sites and newly identified ER retention motifs restored localization of ADAM22 at the cell surface. These results reveal a role for 14-3-3 proteins in targeting ADAM22 to the membrane by masking ER retention signals.