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Establishing a Mouse Model of a Pure Small Fiber Neuropathy with the Ultrapotent Agonist of Transient Receptor Potential Vanilloid Type 1
Published on: February 13, 2018
A pore forming peptide from spider Lachesana sp. venom induced neuronal depolarization and pain
Masayoshi Okada1, Gerardo Corzo2, Gustavo A Romero-Perez1
1Department of Pysiology, Kansai Medical University, Hirakata, Osaka 573-1010, Japan.
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.
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