Monoclonal antibodies against boar sperm zona pellucida-binding protein AWN-1. Characterization of a continuous antigenic determinant and immunolocalization of AWN epitopes in inseminated sows

Boar spermadhesin AWN-1 is a sperm surface-associated 14.7-kDa lectin and a major protein of porcine seminal plasma. AWN-1 binds to beta-galactosides and to porcine zona pellucida glycoproteins, suggesting that this protein might play a role in the primary binding of spermatozoa to the egg's external glycoprotein matrix. We have produced a collection of murine monoclonal antibodies against purified AWN-1. Five monoclonal antibodies recognized sequential antigenic determinants. All these epitopes were located at the C-terminal region of AWN-1 (residues 109-123) by competitive ELISA using overlapping synthetic peptides that cover the complete 133 amino acid sequence of the lectin. In a structural model of spermadhesin AWN-1, the polypeptide stretch 109-123 is fully solvent-exposed, providing a reasonable explanation for its high immunogenicity. In addition to epitope mapping, we have employed anti-AWN monoclonal antibodies for immunolocalization of the protein in the genital tract of inseminated sows. Clusters of AWN epitopes were occasionally found attached to the epithelium of the uterotubal junction and the adjacent lower isthmus. However, neither AWN-1 nor other seminal plasma proteins were found in the isthmic fluid collected 10-26 h after insemination. These results suggest that the whole amount of seminal plasma proteins are absorbed by the epithelium of the female genital tract, supporting the claim that removal of seminal plasma components from spermatozoa might be a major event in both in vitro and in vivo sperm capacitation.

Positioning atypical protein kinase C isoforms in the UV-induced apoptotic signaling cascade

Recent studies have documented the involvement of the atypical protein kinase C (aPKC) isoforms in important cellular functions such as cell proliferation and survival. Exposure of cells to a genotoxic stimulus that induces apoptosis, such as UV irradiation, leads to a profound inhibition of the atypical PKC activity in vivo. In this study, we addressed the relationship between this phenomenon and different proteins involved in the apoptotic response. We show that (i) the inhibition of the aPKC activity precedes UV-induced apoptosis; (ii) UV-induced aPKC inhibition and apoptosis are independent of p53; (iii) Bcl-2 proteins are potent modulators of aPKC activity; and (iv) the aPKCs are located upstream of the interleukin-converting enzyme-like protease system, which is required for the induction of apoptosis by both Par-4 (a selective aPKC inhibitor) and UV irradiation. We also demonstrate here that inhibition of aPKC activity leads to a decrease in mitogen-activated protein (MAP) kinase activity and simultaneously an increase in p38 activity. Both effects are critical for the induction of apoptosis in response to Par-4 expression and UV irradiation. Collectively, these results clarify the position of the aPKCs in the UV-induced apoptotic pathway and strongly suggest that MAP kinases play a role in this signaling cascade.

Immunohistochemical localization in the stallion genital tract, and topography on spermatozoa of seminal plasma protein SSP-7, a member of the spermadhesin protein family

SSP-7 is a protein originally isolated from stallion seminal plasma. It has extensive amino acid sequence homology with boar spermadhesin AWN, and, like its porcine counterpart, SSP-7 displays zona pellucida-binding activity. Strikingly, however, immunohistochemical studies presented here show that the stallion and the boar spermadhesin homologues are secreted at different places of the male genital tract. Furthermore, indirect immunofluorescence shows that the topography of SSP-7 on the surface of stallion spermatozoa is restricted to the equatorial segment, whereas boar AWN epitopes cover the entire acrosomal cap membrane. The different cellular origin and compartimentalization of spermadhesin molecules in different species suggest that structurally related proteins could be involved in species-specific aspects of mammalian fertilization.

The novel HLA-Cw*1802 allele is associated with B*5703 in the Bubi population from Equatorial Guinea

The HLA-Cw*1801 specificity, a Cw7/Cw4 hybrid allele, has recently been described in association with B*8101 (formerly B"DT"). In this study, the new Cw*1802 variant, differing from Cw*1801 at exon 5, is found associated with B*5703 in Bubi individuals from Equatorial Guinea. Confirmatory complete coding regions of B*5703 and B*3910 are also reported.

Isolation and characterization of heparin- and phosphorylcholine-binding proteins of boar and stallion seminal plasma. Primary structure of porcine pB1

In the bovine, seminal plasma heparin-binding proteins bind to sperm lipids containing the phosphorylcholine group and mediate the capacitating effects of heparin-like glycosaminoglycans during sperm residence in the female genital tract. We report the characterization of heparin- and phosphorylcholine-binding proteins of stallion and boar seminal plasma. Horse seminal plasma proteins HSP-1 and HSP-2, and boar protein pB1, belong to the same family as the bull heparin- and phosphorylcholine-binding proteins BSP-A1/2, BSP-A3, and BSP-30K. We have determined the amino acid sequence and posttranslational modifications of boar glycoprotein pB1. It contains 105 amino acids arranged into a mosaic structure consisting of a N-terminal 18-residue O-glycosylated polypeptide followed by two tandemly organized 40-45-residue fibronectin type II domains. pB1 displays 60-65% amino acid sequence similarity with its equine and bovine homologues. However, in their respective seminal plasmas, the BSP and the HSP proteins associate into 90-150-kDa oligomeric complexes, whereas pB1 forms a 35-40-kDa complex with spermadhesin AQN-1. In addition, pB1 appears to be identical to the recently described leukocyte adhesion regulator of porcine seminal fluid pAIF-1. Our results tie in with the hypothesis that homologous proteins from different mammalian species may display distinct biological activities, which may be related to species-specific aspects of sperm physiology.

Fractionation and characterization of boar seminal plasma spermadhesion PSP-II glycoforms reveal the presence of uncommon N-acetylgalactosamine-containing N-linked oligosaccharides

Lectin mapping, carbohydrate analysis and electrospray mass spectrometry of boar seminal plasma PSP-II glycoforms show that its single N-glycosylation site displays a repertoire of carbohydrate structures consisting of the basic pentasaccharide core Man alpha 1-6[Man alpha 1-3]Man beta1-4GlcNAc beta1-4GlcNAc with a fucosyl residue alpha1-6-linked to the innermost N-acetylglucosamine residue. Other glycoforms display fucosylated hybrid-type or monoantennary complex-type chains, some of which contain alpha2-6-linked sialic acid. N-acetylgalactosamine, possibly in Gal beta1-3GalNAc sequence, is present in most of the PSP-II glycoforms.

Primary structure of stallion seminal plasma protein HSP-7, a zona-pellucida-binding protein of the spermadhesin family

The primary-structure of HSP-7, a 14-kDa protein isolated from stallion seminal plasma, has been determined, HSP-7 belongs to the spermadhesin protein family, shares 98% sequence identity with the boar seminal plasma protein AWN, and, like its boar homolog, displays zona-pellucida-binding activity. Despite these conserved structural and functional features, the equine and porcine spermadhesins differ in their topography on spermatozoa.

The primary structure of BSP-30K, a major lipid-, gelatin-, and heparin-binding glycoprotein of bovine seminal plasma

BSP-30K is a major acidic glycoprotein of bovine seminal plasma. It displays heparin-, gelatin-, and phospholipid-binding activities. BSP-30K binds to spermatozoa upon ejaculation and is thought to play a role in sperm capacitation. We have determined its amino acid sequence, disulfide bonds, and 0-glycosylation sites. BSP-30K consists of 158 amino acids arranged in a mosaic structure. BSP-30K has a unique 48-residue N-terminal extension which includes three 7-8- amino acid repeats and the six O-glycosylated threonine residues. The polypeptide stretch 49-71 is homologous to type 'A' domains found in heparin-binding proteins from other mammalian species. The C-terminal portion of BSP-30K is organized in a tandem of 40-44-residue domains each sharing the consensus pattern of the gelatin-binding fibronectin type II module. The mosaic structure of BSP-30K suggests that this glycoprotein might be a factor contributing to the different sperm-capacitating effects exerted by heparin in different mammalian species.

Molecular cloning of two new HLA-C alleles: Cw*1801 and Cw*0706

Nucleotide sequence analysis of the HLA-C alleles of the GB92 cell line, heterozygous for B*8101 and B*4407, revealed the existence of two new allelic variants: Cw*1801 and Cw*0706. The former allele, initially detected as a PCR-SSP variant, displays a hybrid aspect, sharing sequence motifs with Cw*07 at exons 1 and 2, and with Cw*04 at distal exons. In serological assays, Cw*1801 is only recognized by some cross-reactive sera. Cw*0706 shows a primary structure closely related to previously known Cw7 alleles, but carries new sequence motifs at its 3'-end. Preliminary data indicate that Cw*1801 is associated to B*8101 and that Cw*0706, B*4407 could account for a part of the Cw7, B44 haplotypes observed in African populations.

[Chronic myeloid leukemia after renal transplantation: report of a new case and review of the bibliography]

The increase in cancer incidence in renal transplant recipients is a well recognized fact, which has been related to post-transplant immunosuppressive therapy. Solid tumors, skin cancer and non-Hodgkin's lymphomas account for most of the neoplasms in these patients, whereas chronic myeloproliferative disorders are infrequent. A patient is reported who developed chronic myelogenous leukemia (CML) six years after renal transplantation, which was followed by immunosuppressive with azathioprine, and the published data on such an association are reviewed. In all 10 cases reported azathioprine had been administered after transplantation. The amount and type of post-transplant immunosuppressive therapy seems to be the most important risk factor for the development of secondary CML in these patients, since no cases of CML in patients receiving cyclosporine A have been reported.

The product of par-4, a gene induced during apoptosis, interacts selectively with the atypical isoforms of protein kinase C

The atypical PKCs are involved in a number of important cellular functions, including cell proliferation. We report here that the product of the par-4 gene specifically interacts with the regulatory domains of zeta PKC and lambda/LPKC, which dramatically inhibits their enzymatic activity. This is particularly challenging, because expression of par-4 has been shown to correlate with growth inhibition and apoptosis. Results are shown here demonstrating that the expression of par-4 in NIH-3T3 cells induces morphological changes typical of apoptosis, which are abrogated by cotransfection of either wild-type zeta PKC or lambda/LPKC, but not by their respective kinase-inactive mutants. These findings support a role for the atypical PKC subspecies in the control of cell growth and survival.

A procedure for the large-scale isolation of major bovine seminal plasma proteins

A method for the stepwise purification of bovine seminal plasma proteins aSFP, PDC-109, TIMP-2, RNAse, and BSP-30K/PDC-109 complex is presented. It is based on the use of nondenaturing, classical chromatographic procedures. The isolation protocol is reproducible, inexpensive, easy to carry out in a common laboratory, and yields large amounts of pure proteins for biochemical and structural studies.

Cross-talk between different enhancer elements during mitogenic induction of the human stromelysin-1 gene

Platelet-derived growth factor (PDGF) induces the expression of human stromelysin-1, a matrix metalloproteinase involved in tumor invasion and metastasis. Here it is shown that stromelysin-1 gene induction by PDGF depends on Ras and involves three previously identified promoter elements (the stromelysin-1 PDGF-responsive element (SPRE) site, the two head-to-head polyomavirus enhancer A-binding protein-3 (PEA3) sites, and the activator protein-1 (AP-1) binding site). During mitogenic induction, these responsive elements appear to be organized in two independent transcriptional units, SPRE-AP-1 and PEA3-AP-1, which result from specific element cross-talking. Interestingly, expression of a dominant negative mutant of Raf-1 significantly interfered with the induction through PEA3-AP-1 but not with that operating through SPRE-AP-1. Conversely, only the induction operating through SPRE-AP-1 was affected significantly by the expression of a dominant negative mutant of the atypical lambda/iota protein kinase C (lambda/iotaPKC). These data strongly suggest that the signal triggered by PDGF flows through Ras and bifurcates toward two distinct pathways, one operating through Raf and involving PEA3-AP-1 and the other one Raf-independent, operating through lambda/iotaPKC and SPRE-AP-1. Furthermore, we present evidence suggesting that the novel SPRE-binding transcription factor SPBP cross-couples with c-Jun to transactivate the SPRE site.

Boar spermadhesins AQN-1 and AQN-3: oligosaccharide and zona pellucida binding characteristics

AQN-1 and AQN-3 form part of the complement of surface-associated lectins which coat the plasma membrane overlying the acrosomal cap of in vitro capacitated boar spermatozoa. They belong to the spermadhesin protein family and have binding affinity for glycoconjugates of the zona pellucida, the extracellular investment surrounding mammalian eggs. The oligosaccharide and zona pellucida binding characteristics of spermadhesins AQN-1 and AQN-3 were investigated using a solid-phase assay and biotinylated glycoprotein ligands. Both sperm proteins bind glycoproteins containing Gal beta (1-4)-GlcNAc and Gal beta-(1-3)-GalNAc oligosaccharide sequences with dissociation constants (Kd) of 0.08 to 0.8 microM, and to zona pellucida glycoproteins with Kd = 0.15-0.25 microM. However, 5-N-acetyl neuraminic acid alpha (2-3/6)-linked to the galactose residue decreases the affinity of glycosylated ligands to AQN-1 three-fold, although it did not affect oligosaccharide binding to AQN-3. In addition, AQN-3 binds preferentially to glycoproteins with either a linear or tri- and tetraantennary carbohydrates than to those containing diantennary N-acetyllactosamine structures. The similar but distinct oligosaccharide recognition capabilities of spermadhesins AQN-1 and AQN-3 (this work) and AWN-1 (Dostálová, Z, Calvete, J.J., Sanz, L., and Töpfer-Petersen, E. (1995) Eur. J. Biochem. 230, 329-336) suggest that, in the pig, sperm-zona pellucida binding might be mediated by lectins displaying similar although distinct carbohydrate-recognition abilities.

[Occult involvement of bone marrow in Hodgkin's disease: detection with magnetic resonance]

Although bone marrow biopsy is considered the best procedure to detect bone marrow involvement by Hodgkin's disease (HD), in recent years several studies have emphasized the value of magnetic resonance imaging (MRI). We present the case of a patient with HD apparently localized in a laterocervical lymph node, who also referred disestasiae at a region corresponding to D10 metamera. Bone marrow biopsy, vertebral TC and 67-Ga scintigraphy were all normal. However, a node of 1 cm in diameter was detected by MRI in the tenth dorsal vertebra. Because of the topographic coincidence between the patient's symptomatology and the MRI findings, the HD was considered to be in advanced stage and CMOPP/ABV chemotherapy was administered, this resulting in a rapid improvement of symptoms and disappearance of the MRI abnormalities. Since in the present case, the MRI determined a change in disease stage and treatment, the role of MRI as a complementary exploration of bone marrow biopsy to detect marrow involvement by HD is reviewed.

Haplotypic association of two new HLA class I alleles: Cw*15052 and B*0706: evolutionary relationships of HLA-Cw*15 alleles

A novel HLA-Cw*15, B7 haplotype has been found in Caucasians. Molecular cloning studies demonstrate that this haplotype is constituted by the new alleles Cw*15052 and B*0706, which seem to be intermediate steps in the diversification of their respective allelic families. A pathway for the evolution of Cw*15 alleles is proposed.

Crystallization and preliminary X-ray diffraction analysis of boar seminal plasma spermadhesin PSP-I/PSP-II, a heterodimer of two CUB domains

Boar spermadhesin PSP-I/PSP-II (M(r) 29 000-30 000), a non-covalent heterodimer of two CUB domains, was crystallized in two crystal forms. Complete diffraction data sets for hexagonal (space group P6(1,5)22) and trigonal (space group P3(1,2)21) crystals have been collected up to 2.9 and 2.5 angstrom resolution, respectively. Cell constants of the hexagonal and trigonal crystal forms are a=b=87.2 angstrom, c=152.4 angstrom, and a=b=96.2 angstrom, c=70.8 angstrom, respectively. The calculated packing parameters (Vm) are 2.8 and 3.2 angstrom(3)/DA for the hexagonal and trigonal crystal forms, respectively, indicating that, in both cases, the asymmetric unit is constituted by one PSP-I/PSP-II heterodimer. This paper reports the first crystals of a protein built up by a CUB domain architecture.

Mapping the heparin-binding domain of boar spermadhesins

Boar spermadhesins are a group of seminal plasma, heparin-binding proteins which appear to be involved in sperm capacitation and gamete interaction. Using a proteolytic protection assay we have identified regions of AQN-1, AQN-3, PSP-I and AWN which remain attached to a heparin-Sepharose column following in-column digestion of bound spermadhesins with chymotrypsin and elastase. In addition, the complete amino acid sequence of spermadhesin AWN was synthesized as overlapping peptides, and their ability to bind to a heparin-Sepharose column and to inhibit the interaction of soluble heparin with purified ELISA plate-coated AWN was tested. Both approaches gave similar results and as a whole showed that different regions of AWN may converge in its tertiary structure to form a composite heparin-binding site. The conformational heparin-binding surface resides on the GFCC'C'' face of the proposed structural model for AWN and is in an opposite location to the carbohydrate-binding region of the spermadhesin.

Evidence for a role of MEK and MAPK during signal transduction by protein kinase C zeta

Protein kinase C zeta (zeta PKC) is critically involved in the control of a number of cell functions, including proliferation and nuclear factor kappa B (NF-kappa B) activation. Previous studies indicate that zeta PKC is an important step downstream of Ras in the mitogenic cascade. The stimulation of Ras initiates a kinase cascade that culminates in the activation of MAP kinase (MAPK), which is required for cell growth. MAPK is activated by phosphorylation by another kinase named MAPK kinase (MEK), which is the substrate of a number of Ras-activated serine/threonine kinases such as c-Raf-1 and B-Raf. We show here that MAPK and MEK are activated in vivo by an active mutant of zeta PKC, and that a kinase-defective dominant negative mutant of zeta PKC dramatically impairs the activation of both MEK and MAPK by serum and tumour necrosis factor (TNF alpha). The stimulation of other kinases, such as stress-activated protein kinase (SAPK) or p70S6K, is shown here to be independent of zeta PKC. The importance of MEK/MAPK in the signalling mechanisms activated by zeta PKC was addressed by using the activation of a kappa B-dependent promoter as a biological read-out of zeta PKC.

Identification by affinity chromatography of boar sperm membrane-associated proteins bound to immobilized porcine zona pellucida. Mapping of the phosphorylethanolamine-binding region of spermadhesin AWN

We have identified boar sperm membrane components recovered by affinity chromatography on a porcine zona pellucida affinity column. The major zona pellucida-bound proteins were spermadhesins AWN and AQN-3, the heparin-binding protein pAIF, and a homolog of the mouse milk fat globule membrane protein. All these proteins are phospholipid-binding proteins peripherally associated with the plasma membrane. Our data suggest that coating proteins tightly bound to the external lipid bilayer may act as major zona pellucida-binding molecules. Using a synthetic peptide approach we show that the regions of spermadhesin AWN comprising residues 6-12 and 104-108 possess affinity for phosphorylethanolamine. These two amino acid sequences are in close proximity in the predicted structural model for AWN, and in opposite location to its carbohydrate-recognition domain. Taken together, our data provide further evidence for the possible involvement of members of the porcine spermadhesin protein family in gamete interaction and suggest a model for the ultrastructural disposition of functional domains of spermadhesin AWN bound to the sperm surface.

Immunohistochemical localization of spermadhesin AWN in the porcine male genital tract

Boar spermadhesin (AWN) is a 14-kDa multifunctional protein, attached to the surface of the spermatozoa and involved in sperm capacitation and zona pellucida binding. The cellular origin of AWN was previously unknown. Moreover, the region of the male genital tract in which AWN becomes attached to the surface of spermatozoa was also uncertain. By using monospecific polyclonal antibodies against AWN, the immunohistochemical distribution pattern of AWN epitopes has been investigated in tissue sections of the porcine male genital tract. Our study has revealed that AWN is synthesized in the rete testis and in the epithelium of the seminal vesicles. The latter are also the major contributors of seminal plasma AWN. In addition, immunoblotting analysis has shown that AWN is present on epididymal spermatozoa. Our results indicate that the cellular origin of spermadhesins is species-specific. The attachment of AWN to epididymal spermatozoa is probably important in developing the capacity for fertilization.