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PKC inhibition results in a Kv 1.5 + Kv ?1.3 pharmacology closer to Kv 1.5 channels.

ABSTRACT: The Kv ?1.3 subunit modifies the gating and pharmacology of Kv 1.5 channels in a PKC-dependent manner, decreasing channel sensitivity to bupivacaine- and quinidine-mediated blockade. Cardiac Kv 1.5 channels associate with receptor for activated C kinase 1 (RACK1), the Kv ?1.3 subunit and different PKC isoforms, resulting in the formation of a functional channelosome. The aim of the present study was to investigate the effects of PKC inhibition on bupivacaine and quinidine block of Kv 1.5 + Kv ?1.3 channels.HEK293 cells were transfected with Kv 1.5 + Kv ?1.3 channels, and currents were recorded using the whole-cell configuration of the patch-clamp technique. PKC inhibition was achieved by incubating the cells with either calphostin C or bisindolylmaleimide II and the effects of bupivacaine and quinidine were analysed.The voltage-dependent inactivation of Kv 1.5 + Kv ?1.3 channels and their pharmacological behaviour after PKC inhibition with calphostin C were similar to those displayed by Kv 1.5 channels alone. Indeed, the IC50 values for bupivacaine were similar in cells whose PKC was inhibited with calphostin C or bisindolylmaleimide II. Similar results were also observed in the presence of quinidine.The finding that the voltage-dependence of inactivation and the pharmacology of Kv 1.5 + Kv ?1.3 channels after PKC inhibition resembled that observed in Kv 1.5 channels suggests that both processes are dependent on PKC-mediated phosphorylation. These results may have clinical relevance in diseases that are characterized by alterations in kinase activity.

SUBMITTER: Macias A

PROVIDER: S-EPMC4294114 | biostudies-other | 2014 Nov

REPOSITORIES: biostudies-other

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PKC inhibition results in a Kv 1.5 + Kv β1.3 pharmacology closer to Kv 1.5 channels.

Macías A A de la Cruz A A Prieto A A Peraza D A DA Tamkun M M MM González T T Valenzuela C C

British journal of pharmacology 20140905 21

<h4>Background and purpose</h4>The Kv β1.3 subunit modifies the gating and pharmacology of Kv 1.5 channels in a PKC-dependent manner, decreasing channel sensitivity to bupivacaine- and quinidine-mediated blockade. Cardiac Kv 1.5 channels associate with receptor for activated C kinase 1 (RACK1), the Kv β1.3 subunit and different PKC isoforms, resulting in the formation of a functional channelosome. The aim of the present study was to investigate the effects of PKC inhibition on bupivacaine and qu ...[more]

PMID: 24946104

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Project description:Kv channels form voltage-dependent potassium selective pores in the outer cell membrane and are composed out of four ?-subunits, each having six membrane-spanning ?-helices (S1-S6). The ?-subunits tetramerize such that the S5-S6 pore domains co-assemble into a centrally located K(+) pore which is surrounded by four operational voltage-sensing domains (VSD) that are each formed by the S1-S4 segments. Consequently, each subunit is capable of responding to changes in membrane potential and dictates whether the pore should be conductive or not. K(+) permeation through the pore can be sealed off by two separate gates in series: (a) at the inner S6 bundle crossing (BC gate) and (b) at the level of the selectivity filter (SF gate) located at the extracellular entrance of the pore. Within the last years a general consensus emerged that a direct communication between the S4S5-linker and the bottom part of S6 (S6(c)) constitutes the coupling with the VSD thus making the BC gate the main voltage-controllable activation gate. While the BC gate listens to the VSD, the SF changes its conformation depending on the status of the BC gate. Through the eyes of an entering K(+) ion, the operation of the BC gate apparatus can be compared with the iris-like motion of the diaphragm from a camera whereby its diameter widens. Two main gating motions have been proposed to create this BC gate widening: (1) tilting of the helix whereby the S6 converts from a straight ?-helix to a tilted one or (2) swiveling of the S6(c) whereby the S6 remains bent. Such motions require a flexible hinge that decouples the pre- and post-hinge segment. Roughly at the middle of the S6 there exists a highly conserved glycine residue and a tandem proline motif that seem to fulfill the role of a gating hinge which allows for tilting/swiveling/rotations of the post-hinge S6 segment. In this review we delineate our current view on the operation of the BC gate for controlling K(+) permeation in Kv channels.

Dataset Information

PKC inhibition results in a Kv 1.5 + Kv ?1.3 pharmacology closer to Kv 1.5 channels.

Publications

PKC inhibition results in a Kv 1.5 + Kv β1.3 pharmacology closer to Kv 1.5 channels.

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