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Citation
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Okada M, Corzo G, Romero-Perez GA, Coronas FIV, Matsuda H, Possani LD. Biochim. Biophys. Acta 2014; 1850(4): 657-666. |
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Affiliation
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Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, Mexico. |
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Abstract
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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. GENERAL SIGNIFICANCE: Our data suggested an additional physiological role of the pore-forming peptides.
Language: en |