In vitro and in vivo evaluation of small interference RNA-mediated gynaecophoral canal protein silencing in Schistosoma japonicum.

BACKGROUND: Schistosomiasis causes liver and intestinal damage and can be very debilitating. The pairing of a male worm with a female worm residing in the gynaecophoral canal of male plays a critical role in the development of female parasite. Because the male specific gynaecophoral canal protein of Schistosoma japonicum (SjGCP) is found in significant quantities in the adult female worm after pairing, it could play an important role in parasite pairing. METHODS: In the present study, three small interfering (si)RNA duplexes targeting the SjGCP gene were designed, synthesized and the silencing effects were evaluated in vitro as well as in mice infected with S. japonicum in vivo. RESULTS: In vitro studies using semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time RT-PCR revealed the reduction of SjGCP at the transcript level. Similarly, western blotting and immunofluorescence studies showed its reduction at the protein level after treatment of parasites with siRNAs. At a concentration of 200 nM, two siRNAs totally abolished the parasite pairing. To evaluate such a pairing inhibitory effect in vivo, mice infected with S. japonicum were treated with siRNA and both parasite pairing and burden were evaluated. In vivo tests confirmed the in vitro silencing effect of SjGCP siRNA and revealed that the systemic delivery of siRNA significantly inhibited early parasite pairing and the associated burden. CONCLUSIONS: Our preliminary results demonstrated that the SjGCP plays an important role in pairing and subsequent development in S. japonicum, and its silencing might have potential as a therapeutic approach for controlling schistosomiasis.

[Effect of ventral prostate secretory proteins on oviductal fluid glycoproteins in golden hamsters].

OBJECTIVE: To investigate the effect of the secretory proteins of the ventral prostate on the glycoproteins in the oviductal fluid of golden hamsters. METHODS: Male golden hamsters were divided into four groups: sham operation (SH), total removal of accessory sex glands (TX), and retainment of the ventral prostate only (VP). Oviductal fluid was collected from female hamsters at 0.5, 2, 4 and 6 h after mating with the males of different operated groups with or without ventral prostate. Glycoproteins were probed with a panel of lectins and their changes in the oviductal fluid were analyzed by Western blot. RESULTS: The 47 000, 52 000, 81 000 and 128 000 WGA-binding proteins were observed in the oviductal fluid of the 6 h TX group, the 32 000, 35 500, 47 000 and 52 000 WGA-binding glycoproteins noted in the 6 h VP group, the 47 000, 68 000, 95 000 and 128 000 pisum sativum agglutinin (PSA)-binding glycoproteins shown in the 6 h TX and VP groups, two extra 32 000 and 37 500 bands detected in the 6 h VP group, the 47 000 and 52 000 dolichos biflorus agglutinin (DBA)-binding glycoproteins present in the 6 h VP but absent in the 6 h TX group. CONCLUSION: Ventral prostate secretory proteins affect acetylglucosamine, N-acetylgalactosamine/galactose and mannose in the oviductal fluid collected 6 hours after mating. And these glycoproteins may play an important role in the development of embryos.

[Identification of sperm-binding proteins in the ventral prostate of the golden hamster].

OBJECTIVE: To investigate the binding of secretory proteins in the ventral prostate to the surface of sperm. METHODS: We used different techniques to demonstrate the possibility of ventral prostate secretory proteins binding to sperm in golden hamsters. Polyclonal antibodies against crude secretion of the ventral prostate cultured in rabbits were used to detect the antigens in hamster epididymal, uterine and oviductal spermatozoa by indirect immunofluorescence technique. The uterine and oviductal spermatozoa were collected after mating with the males with or without ventral prostate glands. The ventral prostate secretory proteins were isolated and transblotted to the membrane, which was incubated with the biotinylated epididymal sperm membrane proteins, and then the biotinylated binding proteins were stained. RESULTS: An immunoreaction restricted to the middle piece was observed in the sperm incubated with the ventral prostate secretion and ejaculated sperm recovered from the uteri and oviducts. The rate of the epididymal sperm bound with the ventral prostate secretory proteins was (80 +/- 5) %, and the rats of the sperm binding to the ventral prostate secretory proteins were (30.0 +/- 4.6) % from the uterus and (16.0 +/- 3.6) % from the oviduct after mating with the males with ventral prostate glands, significantly higher than after mating with those without prostate glands (P < 0.01). Five bands were identified by Western blot analysis in vitro of the ventral prostate secretory proteins incubated with biotinylated epididymal sperm membrane proteins. CONCLUSION: The present data indicate that ventral prostate secretory proteins bind to the middle piece of sperm in golden hamsters.

Screening of an antigen target for immunocontraceptives from cross-reactive antigens between human sperm and Ureaplasma urealyticum.

Epidemiologic studies indicated that some infertile men who were infected with Ureaplasma urealyticum displayed positive antisperm antibodies in their serum and/or semen. The purpose of this study was to investigate the possible mechanism of antisperm antibodies production after infection with U. urealyticum and to analyze the relationship between U. urealyticum and infertility. The existence of cross-reactive antigens (61, 50, and 25 kDa) between U. urealyticum and human sperm membrane proteins was confirmed. Among the cross-reactive antigens, the urease complex component UreG of U. urealyticum was determined. By searching the Swiss-Prot protein database, a pentapeptide identity (IERLT) between UreG and human nuclear autoantigenic sperm protein (NASP) was found. Furthermore, using Western blot analysis and enzyme-linked immunosorbent assay, the cross-reaction between the NASP and UreG was verified. Both anti-rUreG antibody and the antiserum against the synthetic peptide NASP393-408 containing the pentapeptide inhibited mouse sperm egg binding and fusion. After immunization by rUreG or the synthetic peptide, 81.2 and 75% female mice became sterile, respectively. The effect on fertility in mice immunized with the synthetic peptide was reversible. These findings proved for the first time that it was feasible to screen antigens for immunocontraceptives from cross-reactive antigens between sperm and microorganisms which induce infertility.

Structural and functional analysis of natrin, a venom protein that targets various ion channels.

Cysteine-rich secretory proteins (CRISPs) are secreted single-chain proteins found in different sources. Natrin is a member of the CRISP family purified from the snake venom of Naja naja atra, which has been reported as a BKca channel blocker. In our study, crystals of natrin were obtained in two different crystal forms and the structure of one of them was solved at a resolution of 1.68A. Our electrophysiological experiments indicated that natrin can block the ion channel currents of the voltage-gated potassium channel Kv1.3. Docking analyses of the interaction between natrin and Kv1.3 revealed a novel interaction pattern different from the two previously reported K(+) channel inhibition models termed "functional dyad" and "basic ring". These findings offered new insights into the function of natrin and how the specific interactions between CRISPs and different ion channels can be achieved.

Shedaoenase, a novel fibrinogenase from the venom of Agkistrodon shedaoenthesis Zhao.

Shedaoenase, a serine protease, was isolated from the venom of Agkistrodon shedaoenthesis Zhao with an apparent molecular mass of 36 kDa. It was purified by affinity chromatography on arginine Sepharose 4B column and anion exchange on Mono Q fast protein liquid chromatography. Shedaoenase preferentially cleaved the Aalpha-chain of human fibrinogen and slowly digested the Bbeta-chain. It also showed arginyl esterase activity using Nalpha-benzoyl-L-arginine ethyl ester as a substrate, and some synthetic chromogentic substrates, such as Chromozym PL, S-2266, and S-2160, could also be hydrolyzed. The enzyme activity of shedaoenase could be completely inhibited by phenylmethylsulphonylfluoride and could be little inhibited by the chelating reagent EDTA. The N-terminal sequence of shedaoenase was determined, and its full-length cDNA encoding a protein of 238 amino acid residues was cloned by reverse transcription-polymerase chain reaction from the total mRNA extracted from the snake venom gland. The deduced primary sequence of shedaoenase shares significant homology with other snake venom serine proteases.

Dose-dependent inhibition of gynecophoral canal protein gene expression in vitro in the schistosome (Schistosoma japonicum) by RNA interference.

The gynecophoral canal protein gene SjGCP of Schistosoma japonicum that is necessary for the pairing between the male and female worms is specifically expressed in the adult male worm. This protein is widely distributed in the adult female worm after pairing. Reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence were employed to analyze the relationship between the RNAi effect and dsRNA dosage in the parasites. The results revealed that the inhibition of SjGCP expression by siRNA is dose-dependent. RT-PCR analysis showed that the SjGCP transcript level was reduced by 75% when 100 nM dsRNA was applied.

Proteomic analysis of differentially expressed proteins between the male and female worm of Schistosoma japonicum after pairing.

Identification of differentially expressed proteins between the male and female worm of Schistosoma japonicum may provide new insights into the development of schistosomes, especially the molecular mechanism of female worm maturation induced by the male worm after pairing. Comparative two-dimensional gel electrophoresis (2-DE) and mass spectrometry were employed to separate and identify differentially expressed proteins between the male and female worm after pairing. Soluble and hydrophobic proteins from egg, schistosomulum (14 days), and female and male worms at adult stage (42 days) were separated by a sequential extraction method followed by 2-DE and 2-DE images were constructed. There were 1016 +/- 67, 1808 +/- 89, 1142 +/- 45 and 1288 +/- 32 spots detected for soluble proteins and 1425 +/- 108, 952 +/- 59, 847 +/- 75 and 965 +/- 69 spots for hydrophobic proteins from egg, schistosomulum, and adult stage female and male worms, respectively. The differentially and uniquely expressed proteins from male and female worms after pairing (42 days) include 41 +/- 4 and 23 +/- 2 unique spots for soluble proteins, and 11 +/- 1 and 26 +/- 3 unique spots for hydrophobic proteins, respectively. Matrix-assisted laser desorption/ionization-time of flight and electrospray ionization-tandem mass spectrometry were employed to analyze 12 unique spots from the female worm and 16 unique spots from the male worm for peptide mass fingerprinting and sequencing. The results showed that the main functions of these differentially expressed proteins were in signal transduction, metabolism and transcriptional regulation etc. Comparison of the schistosomes proteome between male and female worms may permit the identification of protein candidates for the development of vaccines or new targets for drug development against schistosomiasis.

[Purification and characterization of platelet aggregation inhibitor component from venom of agkistrodon halys pallas].

Snake venom proteins,particularly from the viper and elapid families, have been known to contain a number of platelet active components including what cause platelet aggregation or inhibit platelet aggregation. Some of them have potential clinical usefulness for the treatment of human hemorrhagic or thrombotic disease. Agkistrodon halys pallas belonging to viper family is only growing in China. The aim of this study was to purify a human platelet aggregation inhibitor from venom of Agkistrodon halys pallas and determine its biochemical character. Whether a component could inhibit human platelet aggregation was act as a method to follow the tracks of the protein. Crude venom of Agkistrodon halys pallas was loaded onto a DEAE-Sepharose CL-6B chromatography column could gain 6 peaks. A platelet inhibitor with molecular mass of 65 kD on SDS-PAGE, was purified from peak 2 by Sephadex G-75 gel filtration and SP-Sepharose, Mono Q on FPLC. It could inhibit human platelet aggregation induced by ADP, collagen without activities of phospholipase A2, esterase, fibrinogenolytic. It is concluded that a platelet inhibitor can be isolated and purified from venom of Agkistrodon halys pallas and its inhibition of platelet aggregation is does-dependent.

Purification, gene cloning and expression of an acidic phospholipase A2 from Agkistrodon shedaoensis Zhao.

A protein with the activity of phospholipase A(2) named asAPLA(2) was purified to homogeneity from the venom of Agkistrodon shedaoensis Zhao through DEAE-Sepharose CL-6B anion exchange column, Source S, and Mono Q FPLC. Its molecular weight was estimated to be 19 kD by SDS-PAGE, and its pI was about 3.5 by IEF analysis. It inhibited the platelet aggregation that was induced by 1 micromol/ L ADP, and the IC(50) was determined to be 6 micromol/L. Degenerating primer was designed and synthesized according to the N-terminal amino acid sequence of asAPLA(2). Its full-length cDNA was cloned by RT-PCR from the total RNA extracted from the snake venom gland. Its molecular weight and the pI are determined to be 13,649 and 4.39 respectively as calculated by DNAclub and DNAstar software according to the deduced amino acid sequence. Then the gene was cloned into the expression plasmid pET-40b(+) and expressed in E. coli BL21(DE3). Western blot analysis indicated that the expressed protein cross-reacted with the antibody against the native enzyme.

[Purification of a Storage Protein from Aphis craccivora Koch and Its Subunit Characterization].

By using of DE52 Cellulose, Sephadex G-150 and FPLC Q Sepharose chromatography, a storage protein (SP) was purified from Aphis craccivora Koch and its subunit was characterized. Its molecular weight was about 60 kD as determined by SDS-PAGE analysis under both reducing and non-reducing conditions, and its pI was about 5.0. It was a glycoprotein. The protein accumulated in larval hemolymph, and decreased when host turned to adult, and could be detected in adults in very low concentration. According to the molecular weight, amino acids composition, and its dynamic alteration of concentrations, the protein should be a persisting storage protein of hemimetabolous insects.

Structures of cadmium-binding acidic phospholipase A2 from the venom of Agkistrodon halys Pallas at 1.9A resolution.

Phospholipase A(2) coordinates Ca(2+) ion through three carbonyl oxygen atoms of residues 28, 30, and 32, two carboxyl oxygen atoms of residue Asp49, and two (or one) water molecules, forming seven (or six) coordinate geometry of Ca(2+) ligands. Two crystal structures of cadmium-binding acidic phospholipase A(2) from the venom of Agkistrodon halys Pallas (i.e., Agkistrodon blomhoffii brevicaudus) at different pH values (5.9 and 7.4) were determined to 1.9A resolution by the isomorphous difference Fourier method. The well-refined structures revealed that a Cd(2+) ion occupied the position expected for a Ca(2+) ion, and that the substitution of Cd(2+) for Ca(2+) resulted in detectable changes in the metal-binding region: one of the carboxyl oxygen atoms from residue Asp49 was farther from the metal ion while the other one was closer and there were no water molecules coordinating to the metal ion. Thus the Cd(2+)-binding region appears to have four coordinating oxygen ligands. The cadmium binding to the enzyme induced no other significant conformational change in the enzyme molecule elsewhere. The mechanism for divalent cadmium cation to support substrate binding but not catalysis is discussed.

beta-Agkistrodotoxin inhibition of Ca2+-dependent release of glutamate, aspartate, glycine and gamma-aminobutyric acid from cerebrocortical synaptosomes following its binding to synaptic membrane.

The binding properties of beta-AgTX, a snake pre-synaptic toxin, membranes and its effect on transmitter release from cerebrocortical synaptosomes were investigated. Assay of [125I]-beta-AgTX binding to rat synaptic membrane revealed a high affinity binding site for the toxin within the synaptic membrane. Preincubation with beta-AgTX inhibited K+-evoked Ca2+-dependent glutamate release from synaptosomes in a concentration-dependent manner, as determined by an on-line enzyme-linked fluorometric assay. The toxin also blocked the Ca2+-dependent release of other transmitters, aspartate, glycine, and GABA induced by K+-depolarization. However, Ca2+-ionophore, ionomycin-stimulated Ca2+-dependent transmitter release was not significantly affected by beta-AgTX, indicating that the toxin inhibits transmitter release by reducing the entry of Ca2+ into cytoplasm. It is suggested that beta-AgTX-binding site in synaptic membrane is related to the release of a variety of transmitters.

Functionally important residues for the anticoagulant activity of a basic phospholipase A(2) from the Agkistrodon halys pallas.

To identify the anticoagulant region of the phospholipase A(2) (PLA(2)) from the Agkistrodon halys Pallas (class II), four mutants E53G, W70M, T56K, and D67K were produced according to the prediction from the crystal structure and the sequence comparison of the strong, weak and non-anticoagulant PLA2s. A test of blood clotting revealed that E53G and W70M had lost their effects on the blood clotting, while T56K and D67K had enhanced activity. The four residues are located on the same face in the tertiary structure of this enzyme. The result supported the prediction that there exists an anticoagulant region that is composed of some residues that are close to each other in tertiary structure to form a functional face.

Secretory phospholipase A(2) inhibits epidermal growth factor-induced receptor activation.

Secretory phospholipase A(2) (sPLA(2)) plays important roles in mediating various cellular processes, including cell proliferation, differentiation, apoptosis, and inflammatory response. In this study, we demonstrated that a basic sPLA(2) inhibits epidermal growth factor (EGF)-induced EGF receptor activation, as determined by autophosphorylation of EGF receptor, EGF-activated phospholipase D (PLD) activity, and phospholipase C-gamma(1) (PLC-gamma(1)) tyrosine phosphorylation in a human epidermoid carcinoma cell line, A-431. Treatment of cells with exogenous neutral sphingomyelinase (SMase) or a cell permeable ceramide analog, C(2)-ceramide, also caused similar inhibitory effects on EGF-induced activation of EGF receptor, tyrosine phosphorylation of PLC-gamma(1), and the activation of PLD. sPLA(2)-induced inhibition of EGF receptor was associated with arachidonic acid release, which was followed by an increase in intracellular ceramide formation. Both sPLA(2) and exogenous C(2)-ceramide are able to inhibit the proliferation of A-431. The data presented indicate for the first time that sPLA(2) downregulates the EGF receptor-mediated intracellular signal transduction that may be mediated by arachidonic acid and/or ceramide.

Structure of an acidic phospholipase A2 from the venom of Deinagkistrodon acutus.

An acidic phospholipase A(2) was purified from Deinagkistrodon acutus (Agkistrodon acutus) which displays an inhibitory effect on platelet aggregation. The three-dimensional structure of the enzyme was determined by molecular replacement at 2.6 A resolution with a crystallographic R factor of 18.40% (R(free) = 22.50%) and reasonable stereochemistry. Two molecules in the asymmetric unit form a dimer and the dimer formation accompanies a significant conformational adaptation of segment 14-23, a constituent of the 'interface recognition site' (IRS). This probably reflects the inherent structural flexibility of the IRS. The possible expansion of the site for inhibiting platelet aggregation as proposed previously [Wang et al. (1996), J. Mol. Biol. 255, 669-676] is discussed.

[Cloning and expression of 21.7 kD protein gene of Schistosoma japonicum (Chinese strain)].

A 558 bp cDNA fragment was amplified by RT-PCR from adult Schistosoma japonicum(Chinese strain) mRNA with a pair of primers that were designed according to published Sj21.7p gene encoding 21.7 kD protein of Schistosoma japonicum(Philippines strain). Sequence analysis indicated that this frame, named Sj21.7 (Ch), with 99% homology to Sj21.7 p, contained a complete open reading fragment (ORF) of 21.7 kD protein gene of Schistosoma japonicum(Chinese strain). The amino acid sequence shared 98% homology with 21.7 kD protein of Schistosoma japonicum. This fragment was cloned into the expression vector pET28a (+) and subsequently expressed in Escherichia coli with IPTG induction. SDS-PAGE analysis revealed that the molecular weight of this expressed product was 25.4 kD. Western blotting showed that the recombinant protein reacted well with the rabbit serum immunized with Sj worm antigen, indicating that this expressed product had good antigenicity.

Structure Determination of Basic Phospholipase A(2) from the Venom of Agkistrodon halys Pallas in A New Monoclinic Crystal Form.

Basic phospholipase A(2) from the venom of Agkistrodon halys Pallas ( Agkistrodin blomhoffii brevicaudus ) exhibits hemolytic and anti-coagulant activities. A new monoclinic crystal form with four molecules per asymmetric unit was grown in the absence of n-octyl beta-o-glucopyranoside (beta-OG). The enzyme structure was determined by the molecular replacement method. The combined analysis of self- and cross- rotation function was used and non-crystallographic symmetry restraints were imposed to the structure refinement. The final model gave an acceptable crystallographic R factor and reasonable stereochemistry. Two molecules formed an interfacial-recognition-site linked dimer and two such dimers constituted a tetramer having pseudo 222 symmetry. Structural comparison with previously reported monoclinic forms, in which beta-OG was bound, showed that the variation of crystallization conditions had effects on the crystal packing, leading to significant changes of the cell parameters. Nevertheless, the structures of both the dimer and tetramer in the two crystal forms closely resembled to each other, indicating that the oligomers found in the monoclinic crystal forms were stable.

Cloning and Expression of Actin Gene of Schistosoma japonicum Chinese Strain.

A 1 131 bp cDNA fragment was amplified by RT-PCR from adult Schistosoma japonicum(Chinese strain) mRNA with primers designed according to published SmAct2 encoding Schistosoma mansoni actin. Sequence analysis indicated that this fragment, with 92% homology to SmAct2, was a complete open reading fragment (ORF) of actin gene of Schistosoma japonicum (Chinese strain). This gene was cloned into the expression vector pET28a( ) and subsequently expressed in Escerichia coli. SDS-PAGE revealed that the molecular weight of this expressed product was 47 kD. Western blotting showed that the recombinant protein had good reactivity with the rabbit serum immunized with Sj worm antigen, indicating that this gene encode actin of Schistosoma japonicum(Chinese strain).

Purification, Crystal Growth and Preliminary X-ray Analysis of a Phospholipase A(2) from Venom of Agkistrondon acutus.

An acidic phospholipase A(2) from Agkistrondon acutus venom has been purified to homogeneity via four steps using CM-Sepharose, two times DEAE-Sepharose, and Mono Q FPLC. The molecular weight of the protein was about 16.5 kD and the isoelectric point was 4.3. The purified enzyme showed a potent inhibitory effect on platelet aggregation induced by ADP in human platelet-enriched plasma. The enzyme was then crystallized by hanging drop diffusion method using 2-methyl-2, 4-pentanediol as a precipitant. Two kinds of single crystals suitable for X-ray crystallographic studies were obtained. X-ray crystallographic analysis showed that both crystal forms belong to monoclinic system and space group P2(1). The cell dimensions of form I crystals were a = 43.48 Aring;, b = 71.49 Aring;, c = 43.85 Aring; and beta = 116.32 deg; Those of form II crystals were a = 49.25 Aring;, b = 38.33 Aring;, c = 70.25 Aring; and beta = 99.20 deg;. Complete diffraction data sets have been collected to medium resolution for the two crystal forms.