Emerging Concepts in Ion Channel Biophysics

Emerging Concepts in Ion Channel Biophysics

Poster Abstracts

40-POS Board 40 Pharmacological Effects Exerted by Polypeptide Fractions Extracted from Centruroides Noxius Venom on the Oncogenic Channel Kv10.1/Eag1 Erika Monserrat Torres-Morales 1 , Arlet Loza-Huerta 1 , Fredy Coronas-Valderrama 2 , Arturo Hernández-Cruz 1 , Lourival Possani 2 , Arturo Picones 1 , Enoch Luis Baltazar 2 , Cesar Oliver Lara Figueroa 2 1 Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, UNAM; 2 Instituto de Biotecnología, UNAM. The potassium channel Ether-a-go-go-1 (Eag1, KV10.1, KCNH1) is found in 70% of tumoral cells and has been linked to processes of cell proliferation, angiogenesis, migration, survival and invasion in a variety of cancers. All this has led to propose Kv10.1 as a relevant therapeutic target. Here we report the evaluation of the action of different polypeptide fractions, isolated by HPLC from the venom of the scorpion Centruroides noxius, on the functional activity of KV10.1 heterologously and stably expressed in HEK293 cells. By means of automated fluorescence technology, measuring Thallium ion influx through Kv10.1, 20 different polypeptide fractions were initially screened, 2 of them were identified as inhibitory hits (Tl influx reduction > 30%) and were further re-fractionated by HPLC. The pharmacological activity of these newly isolated fractions were analyzed by manual patch-clamp electrophysiology. Outward potassium currents through Kv10.1 were measured in response to 200 ms voltage steps from -100 to +50 mv in 10 mV increments applied every 5 s and from a holding voltage of -70 mV. The polypeptide fraction named CnMt9 showed a clear dose-dependent inhibitory effect, characterized by an ID50 of 14.2 ng/ml. Conductance-voltage relationship fitted with a Boltzmann equation showed that CnMt9 shifts the half-activation voltage (V1/2) from 4.7 mV to 23.8 mV and increased the slope factor from /ml) and to V1/2 >100 mV and slope factor

Supported by CONACyT (México) grants 279820 (Laboratorio Nacional de Canalopatías and CB 240305.

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