title: A pore forming peptide from spider Lachesana sp. venom induced neuronal depolarization and pain.
abstract: BACKGROUND
  Arachnoid venoms contain numerous peptides with ion channel modifying and cytolytic activities.
  
  
  METHODS
  We developed a green fluorescent protein (GFP)-based assay that can monitor the changes in currents through overexpressed inwardly rectifying K(+) channels (Kir2.1), in which GFP expression was increased by blockade of Kir2.1 current. Using this assay, we screened venom of many spider species. A peptide causing GFP decreasing effect was purified and sequenced. Electrophysiological and pain-inducing effects of the peptide were analyzed with whole-cell patch-clamp recordings and hot-plate test, respectively.
  
  
  RESULTS
  Among venoms we screened, soluble venom from Lachesana sp. decreased the GFP expression. Purification and sequencing of the peptide showed that the peptide is identical to a pore-forming peptide purified from Lachesana tarabaevi venom. Whole cell patch-clamp recordings revealed that the peptide had no effect on Kir2.1 current. Instead, it induced a current that was attributable to the pore-formation of the peptide. The peptide was selectively incorporated into hyperpolarized, i.e., Kir2.1 expressing, cells and for this reason the peptide decreased GFP expression in our Kir2.1 assay. The pore-formation positively shifted the reversal potential and induced burst firings in the hippocampal neurons in a synaptic current-independent way. The application of the Lachesana sp. peptide induced pain-related behavior in mice.
  
  
  CONCLUSIONS
  The peptide, which was found in Lachesana sp. venom, formed pores and thereby depolarized neurons and induced pain.
  
  
  CONCLUSIONS
  Our data suggested an additional physiological role of the pore-forming peptides.
authors.affiliation: Department of Pysiology, Kansai Medical University, Hirakata, Osaka 573-1010, Japan. Electronic address: mokada-tky@umin.ac.jp.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Okada
authors.affiliation: Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, Mexico.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Corzo
authors.affiliation: Department of Pysiology, Kansai Medical University, Hirakata, Osaka 573-1010, Japan.
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Romero-Perez
authors.affiliation: Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, Mexico.
authors.forename: Fredy
authors.initials: F
authors.lastname: Coronas
authors.affiliation: Department of Pysiology, Kansai Medical University, Hirakata, Osaka 573-1010, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Matsuda
authors.affiliation: Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, Mexico.
authors.forename: Lourival D
authors.initials: LD
authors.lastname: Possani
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D049452:Green Fluorescent Proteins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D010146:Pain / Q000139:chemically induced*; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000494:pharmacology*; D024661:Potassium Channels, Inwardly Rectifying / Q000187:drug effects / Q000502:physiology; D013111:Spider Venoms / Q000737:chemistry / Q000494:pharmacology*
chemical_list: C489461:Kir2.1 channel; D010455:Peptides; D024661:Potassium Channels, Inwardly Rectifying; D013111:Spider Venoms; D049452:Green Fluorescent Proteins
keywords: Arachnoid venom; Depolarization; Inwardly rectifying K(+) channel (Kir2.1); Pain; Pore-forming peptide; Thermal hyperalgesia