Referenced in: none

Automatically associated channels: Kir2.1

Title: A pore forming peptide from spider Lachesana sp. venom induced neuronal depolarization and pain.

Authors: Masayoshi Okada, Gerardo Corzo, Gustavo A Romero-Perez, Fredy Coronas, Hiroko Matsuda, Lourival D Possani

Journal, date & volume: Biochim. Biophys. Acta, 2015 Apr , 1850, 657-66

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/25484315

Abstract
Arachnoid venoms contain numerous peptides with ion channel modifying and cytolytic activities.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.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.The peptide, which was found in Lachesana sp. venom, formed pores and thereby depolarized neurons and induced pain.Our data suggested an additional physiological role of the pore-forming peptides.