title: A Conus regularis conotoxin with a novel eight-cysteine framework inhibits CaV2.2 channels and displays an anti-nociceptive activity.
abstract: A novel peptide, RsXXIVA, was isolated from the venom duct of Conus regularis, a worm-hunting species collected in the Sea of Cortez, México. Its primary structure was determined by mass spectrometry and confirmed by automated Edman degradation. This conotoxin contains 40 amino acids and exhibits a novel arrangement of eight cysteine residues (C-C-C-C-CC-CC). Surprisingly, two loops of the novel peptide are highly identical to the amino acids sequence of ω-MVIIA. The total length and disulfide pairing of both peptides are quite different, although the two most important residues for the described function of ω-MVIIA (Lys2 and Tyr13) are also present in the peptide reported here. Electrophysiological analysis using superior cervical ganglion (SCG) neurons indicates that RsXXIVA inhibits CaV2.2 channel current in a dose-dependent manner with an EC50 of 2.8 μM, whose effect is partially reversed after washing. Furthermore, RsXXIVA was tested in hot-plate assays to measure the potential anti-nociceptive effect to an acute thermal stimulus, showing an analgesic effect in acute thermal pain at 30 and 45 min post-injection. Also, the toxin shows an anti-nociceptive effect in a formalin chronic pain test. However, the low affinity for CaV2.2 suggests that the primary target of the peptide could be different from that of ω-MVIIA.
authors.affiliation: Molecular Immunology and Biotoxins Laboratory, Marine Biotechnology Department, Scientific Research and High Education Center from Ensenada, Ensenada, Mexico. jbernald@cicese.edu.mx
authors.forename: Johanna
authors.initials: J
authors.lastname: Bernáldez
authors.forename: Sergio A
authors.initials: SA
authors.lastname: Román-González
authors.forename: Oscar
authors.initials: O
authors.lastname: Martínez
authors.forename: Samanta
authors.initials: S
authors.lastname: Jiménez
authors.forename: Oscar
authors.initials: O
authors.lastname: Vivas
authors.forename: Isabel
authors.initials: I
authors.lastname: Arenas
authors.forename: Gerardo
authors.initials: G
authors.lastname: Corzo
authors.forename: Roberto
authors.initials: R
authors.lastname: Arreguín
authors.forename: David E
authors.initials: DE
authors.lastname: García
authors.forename: Lourival D
authors.initials: LD
authors.lastname: Possani
authors.forename: Alexei
authors.initials: A
authors.lastname: Licea
mesh_terms: D059787:Acute Pain / Q000188:drug therapy; D000595:Amino Acid Sequence; D000700:Analgesics / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D000818:Animals; D002121:Calcium Channel Blockers / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D020864:Calcium Channels, N-Type / Q000187:drug effects / Q000378:metabolism; D059350:Chronic Pain / Q000188:drug therapy; D020916:Conotoxins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D052078:Conus Snail / Q000737:chemistry*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D008297:Male; D013058:Mass Spectrometry; D008800:Mexico; D051379:Mice; D008813:Mice, Inbred ICR; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D017783:Superior Cervical Ganglion / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors
chemical_list: D000700:Analgesics; C503279:Cacna1b protein, rat; D002121:Calcium Channel Blockers; D020864:Calcium Channels, N-Type; D020916:Conotoxins; D010455:Peptides