Hainantoxin-IV (HNTX-IV) purified from the venom of the spider Selenocosmia hainana is a potent antagonist that acts on tetrodotoxin-sensitive (TrX-S) sodium channels. It is a 35-residue polypeptide and includes three disulfide bridges. In order to investigate the structure-function relationship of HNTX-IV, two mutants (S12A-HNTX-IV and R29A-HNTX-IV) of HNTX-TV in which Ser12 and Arg29 were replaced by Ala respectively, were synthesized by solid-phase Fmoc chemistry, followed by oxidative refolding of purified peptides under the optimal conditions. The synthetic mutants were analyzed by MALDI-TOF mass spectrometry, nuclear magnetic resonance spectroscopy (NMR) and electrophysiological experiments for molecular weight, conformation and physiological activity, respectively. The results show that the mutants and native HNTX-IV (nHNTX-IV) have almost identical three-dimensional structures. The bioactivity level of S12A-HNTX-IV is also about the same as that of nHNTX-IV, suggesting that Ser12 does not play any important role for the bioactivity of this toxin. The bioactivity of R29A-HNTX-IV is reduced by at last 155 times, indicating that Arg29 is a key residue relative to the bioactivity of HNTX-IV. It is presumed that the decrease in activity of R29A-HNTX-IV is due to the changes of the property in the binding site rather than the change in the basic conformation of the molecule.
Amino Acid Substitution ; Animals ; Mutation ; Sodium Channel Blockers ; Sodium Channels ; drug effects ; physiology ; Spider Venoms ; chemical synthesis ; genetics ; Structure-Activity Relationship ; Tetrodotoxin ; pharmacology

This paper focuses on the effect of the venom of the spider Macrothele raveni on the proliferation of human hepatocelluar carcinoma cell line HepG2 and the related molecular mechanism. XTT test showed that the proliferation of HepG2 cells in vitro was inhibited by the spider venom (P<0.05) in a concentration-dependent manner. By using flow cytometry, it was found that the spider venom caused selective G(2)/M cell cycle arrest in HepG2 cells. RT-PCR and Western blot indicated the expressions of p21 mRNA and protein in HepG2 cells were obviously up-regulated by the spider venom. The venom of the spider Macrothele raveni inhibited the proliferation of HepG2 cells. These results suggest that the possible mechanism of the spider venom is to activate the expressions of p21 gene and protein and to cause selective cell cycle arrest at G(2)/M phase, leading to HepG2 cell apoptosis.
Cell Cycle ; drug effects ; Cell Proliferation ; drug effects ; Cyclin-Dependent Kinase Inhibitor p21 ; genetics ; metabolism ; Hep G2 Cells ; Humans ; RNA, Messenger ; genetics ; metabolism ; Spider Venoms ; pharmacology

Huwentoxin-XI (HWTX-XI) is a protein isolated from the crude venom of spider Ornithoctonus huwena. It has 55 amino acid residues containing 6 cysteine residues forming 3 disulfide bonds. It shows potent inhibitory effect on trypsin and voltage-gated potassium channels in rat dorsal root ganglion cells. According to the structure-function relationship of HWTX-XI, we designed two mutants through mutation of potassium channel inhibition related amino acid residues (R5I, R10T,R25A and R5I,R25A) and then expressed them with high purity by using the vector pVT102U on Saccharamyces cerevisiae strain S78; The two mutants had the same trypsin inhibition activity as HWTX-XI, whereas their potassium channel inhibition activity and animal toxicity were much lower than those of HWTX-XI. This study is helpful for designing drugs of trypsin related diseases based on HWTX-XI.
Amino Acid Sequence ; Animals ; Genetic Vectors ; genetics ; Molecular Sequence Data ; Mutant Proteins ; biosynthesis ; genetics ; pharmacology ; Potassium Channel Blockers ; pharmacology ; Rats ; Recombinant Proteins ; biosynthesis ; genetics ; pharmacology ; Saccharomyces cerevisiae ; genetics ; metabolism ; Spider Venoms ; biosynthesis ; genetics ; pharmacology ; Spiders ; Trypsin Inhibitors ; pharmacology

Kv2.1 channel currents in pancreatic beta-cells are thought to contribute to action potential repolarization and thereby modulate insulin secretion. Because of its central role in this important physiological process, Kv2.1 channel is a promising target for the treatment of type 2 diabetes. Jingzhaotoxin-XI (JZTX-XI) is a novel peptide neurotoxin isolated from the venom of the spider Chilobrachys jingzhao. Two-microelectrode voltage clamp experiments had showed that the toxin inhibited Kv2.1 potassium currents expressed in Xenopus Laevis oocytes. In order to investigate the structure-function relationship of JZTX-XI, the natural toxin and a mutant of JZTX-XI in which Arg3 was replaced by Ala, were synthesized by solid-phase chemistry method with Fmoc-protected amino acids on the PS3 automated peptide synthesizer. Reverse-phase high performance liquid chromatography (RP-HPLC) and matrix assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF/TOF MS) were used to monitor the oxidative refolding process of synthetic linear peptides to find the optimal renaturation conditions of these toxins. The experiments also proved that the relative molecular masses of refolded peptides were in accordance with their theoretical molecular masses. RP-HPLC chromatogram of co-injected native and refolded JZTX-XI was a single peak. Under the whole-cell patch-clamp mode, JZTX-XI could completely inhibit hKv2.1 and hNav1.5 channels currents expressed in HEK293T cells with IC50 values of 95.8 nmol/L and 437.1 nmol/L respectively. The mutant R3A-JZTX-XI could also inhibit hKv2.1 and hNav1.5 channel currents expressed in HEK293T cells with IC50 values of 1.22 micromol/L and 1.96 micromol/L respectively. However, the prohibitive levels of R3A-JZTX-XI on hKv2.1 and hNav1.5 channels were reduced by about 12.7 times and 4.5 times respectively, indicating that Arg3 was a key amino acid residue relative to the hKv2.1 channel activity of JZTX-XI, but it is also an amino acid residue correlated with the binding activity of JZTX-XI to hNav1.5 channel. Our findings should be helpful to develop JZTX-XI into a molecular probe and drug candidate targeting to Kv2.1 potassium channel in the pancreas.
Animals ; HEK293 Cells ; Humans ; Insulin-Secreting Cells ; metabolism ; Mutant Proteins ; genetics ; pharmacology ; NAV1.5 Voltage-Gated Sodium Channel ; metabolism ; Neurotoxins ; chemical synthesis ; genetics ; pharmacology ; Protein Refolding ; Shab Potassium Channels ; antagonists & inhibitors ; metabolism ; Sodium Channel Blockers ; pharmacology ; Spider Venoms ; genetics ; pharmacology ; Transfection

Kv4.3 channel is present in many mammalian tissues, predominantly in the heart and central nervous system. Its currents are transient, characterized by rapid activation and inactivation. In the hearts of most mammals, it is responsible for repolarization of the action potential of ventricular myocytes and is important in the regulation of the heart rate. Because of its central role in this important physiological process, Kv4.3 channel is a promising target for anti-arrhythmic drug development. Jingzhaotoxin-V (JZTX-V) is a novel peptide neurotoxin isolated from the venom of the spider Chilobrachys jingzhao. Whole-cell patch clamp recording showed that it partly blocked the transient outward potassium channels in dorsal root ganglion neurons of adult rats with an IC(50) value of 52.3 nmol/L. To investigate the effect of JZTX-V on Kv4.3 channel, JZTX-V was synthesized using the solid-phase chemical synthesis and separated by reverse phase high performance liquid chromatography (HPLC). The purity was tested by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MOLDI-TOF mass spectrometry). Two-electrode voltage-clamp technique was used to characterize the action of JZTX-V on Kv4.3 channels expressed in Xenopus laevis oocytes. As a result, JZTX-V displayed fast kinetics of inhibition and recovery from inactivation. Furthermore, it could inhibit Kv4.3 channel current in a time- and concentration-dependent manner with an IC(50) value of 425.1 nmol/L. The application of JZTX-V affected the activation and inactivation characteristics of Kv4.3 channel and caused a shift of the current-voltage relationship curve and the steady-state inactivation curve to depolarizing direction by approximately 29 mV and 10 mV, respectively. So we deduced that JZTX-V is a gating modifier toxin of Kv4.3 channel. Present findings should be helpful to develop JZTX-V into a molecular probe and drug candidate targeting to Kv4.3 channel in the myocardium.
Animals ; Ganglia, Spinal ; cytology ; Neurons ; drug effects ; Neurotoxins ; pharmacology ; Oocytes ; Patch-Clamp Techniques ; Peptides ; pharmacology ; Potassium Channel Blockers ; pharmacology ; Rats ; Shal Potassium Channels ; metabolism ; Spider Venoms ; pharmacology ; Xenopus laevis

Jingzhaotoxin-V(JZTX-V) isolated from the venom of the spider Chilobrachys jingzhao is a novel potent inhibitor that acts on tetrodotoxin-resistant and tetrodotoxin-sensitive sodium channels in adult rat dorsal root ganglion(DRG) neurons. It is a 29-residue polypeptide toxin including three disulfide bridges. To investigate the structure-function relationship of the toxin, a mutant of JZTX-V in which Arg20 was substituted by Ala, was synthesized by solid-phase chemistry method with Fmoc-protected amino acids on the PS3 automated peptide synthesizer. The synthetic linear peptide was then purified by reversed-phase high performance liquid chromatography and oxidatively refolded under the optimal conditions. The refolded product was analyzed by matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry(MALDI-TOF MS) and electrophysiological experiments for its relative molecular weight and prohibitive activity of sodium channels respectively. The present findings show that the prohibitive effect of R20A-JZTX-V on TTX-S sodium channels in DRG neurons is almost the same as that of native JZTX-V, suggesting that Arg20 does not play any important role in inhibiting TTX-S sodium currents in DRG neurons. In contrast, the prohibitive level of R20A-JZTX-V on TTX-R sodium channels is reduced by at last 18.3 times, indicating that Arg20 is a key amino acid residue relative to the bioactivity of JZTX-V. It is presumed that the decrease in activity of R20A-JZTX-V is due to the changes of the property in the binding site in TTX-R sodium channels.
Amino Acid Substitution ; Animals ; Arginine ; genetics ; Ganglia, Spinal ; drug effects ; Mutagenesis, Site-Directed ; Mutant Proteins ; pharmacology ; Neurons ; drug effects ; Patch-Clamp Techniques ; Peptides ; chemistry ; genetics ; pharmacology ; Rats ; Sodium Channel Blockers ; pharmacology ; Sodium Channels ; drug effects ; Spider Venoms ; chemistry ; genetics ; isolation & purification ; pharmacology ; Spiders ; Tetrodotoxin ; pharmacology

HWTX-I is a peptide neurotoxin purified from the crude venom of the Chinese bird Spider Selenocosmia Huwena, which has analyesic activity. rHWTX-I expressed by P. pastoris and secreted to culture supernatant was first precipitated by (NH4)2SO4, then it was isolated and desalted by ultrofiltration following by ion exchange chromatography of CM column, after reverse phase HPLC of C18 column and vacuum drying, the pure HWTX-I protein was obtained which was proved to be recombinant HWTX-I by Tricine SDS-PAGE, MALDI-TOF mass spectrometry, amino acid composition analysis, the N-terminal amino acid sequence and its biological activity. The final yield of the purified HWTX-I was about 80 mg/L accounting for 23.6% of its total secretory proteins.
Amino Acid Sequence ; Animals ; Chromatography, High Pressure Liquid ; methods ; Chromatography, Ion Exchange ; methods ; Culture Media ; Gene Expression ; Hydrogen-Ion Concentration ; Male ; Mice ; Molecular Sequence Data ; Neuromuscular Junction ; drug effects ; Neurotoxins ; genetics ; isolation & purification ; pharmacology ; Pichia ; Recombinant Fusion Proteins ; genetics ; isolation & purification ; pharmacology ; Reptilian Proteins ; Seminiferous Tubules ; drug effects ; Sequence Analysis, Protein ; Spider Venoms ; genetics ; isolation & purification ; pharmacology ; Spiders ; Synaptic Transmission ; drug effects ; Time Factors

This study aims to validate our hypothesis that acid-sensing ion channels (ASICs) may contribute to the symptom of pain in patients with chronic prostatitis (CP). We first established a CP rat model, then isolated the L5-S2 spinal dorsal horn neurons for further studies. ASIC1a was knocked down and its effects on the expression of neurogenic inflammation-related factors in the dorsal horn neurons of rat spinal cord were evaluated. The effect of ASIC1a on the Ca²⁺ ion concentration in the dorsal horn neurons of rat spinal cord was measured by the intracellular calcium ([Ca²⁺]i) intensity. The effect of ASIC1a on the p38/mitogen-activated protein kinase (MAPK) signaling pathway was also determined. ASIC1a was significantly upregulated in the CP rat model as compared with control rats. Acid-induced ASIC1a expression increased [Ca²⁺]i intensity in the dorsal horn neurons of rat spinal cord. ASIC1a also increased the levels of neurogenic inflammation-related factors and p-p38 expression in the acid-treated dorsal horn neurons. Notably, ASIC1a knockdown significantly decreased the expression of pro-inflammatory cytokines. Furthermore, the levels of p-p38 and pro-inflammatory cytokines in acid-treated dorsal horn neurons were significantly decreased in the presence of PcTx-1, BAPTA-AM, or SB203580. Our results showed that ASIC1a may contribute to the symptom of pain in patients with CP, at least partially, by regulating the p38/MAPK signaling pathway.
Acid Sensing Ion Channel Blockers/pharmacology* ; Acid Sensing Ion Channels/genetics* ; Animals ; Calcium/metabolism* ; Chelating Agents/pharmacology* ; Chronic Disease ; Cytokines/metabolism* ; Disease Models, Animal ; Egtazic Acid/pharmacology* ; Gene Knockdown Techniques ; Imidazoles/pharmacology* ; Inflammation/metabolism* ; MAP Kinase Signaling System/genetics* ; Male ; Pain/genetics* ; Peptides/pharmacology* ; Phosphorylation/drug effects* ; Posterior Horn Cells/metabolism* ; Prostatitis/complications* ; Protein Kinase Inhibitors/pharmacology* ; Pyridines/pharmacology* ; Rats ; Spider Venoms/pharmacology* ; Up-Regulation ; p38 Mitogen-Activated Protein Kinases/metabolism*