Characterization of a novel Ca 2+ -Activated potassium channel in rat brain rough endoplasmic reticulum.

Autor: Fahanik-Babaei J; Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran., Bagheri M; Department of Physiology, Faculty of Medicine, Ilam University of Medical Sciences, Ilam, Iran., Salari S; Department of Physiology, Faculty of Medicine, Ilam University of Medical Sciences, Ilam, Iran. Electronic address: Sajjad.salari@medilam.ac.ir.
Jazyk: angličtina
Zdroj: Archives of biochemistry and biophysics [Arch Biochem Biophys] 2024 Sep; Vol. 759, pp. 110105. Date of Electronic Publication: 2024 Jul 25.
DOI: 10.1016/j.abb.2024.110105
Abstrakt: Objectives: Potassium channels in the endoplasmic reticulum (ER) are crucial for maintaining calcium balance during calcium fluxes. Disruption in ER calcium balance leads to ER stress, implicated in diseases like diabetes and Alzheimer's disease (AD). However, limited data exists on ER potassium channels in excitable tissues such as the brain. To fill this gap, we aimed to evaluate potassium currents in rat brain rough endoplasmic reticulum (RER).
Methods: Rats were euthanized under deep anesthesia and their brains were immediately removed. The brains were then homogenized in ice-cold sucrose buffer, followed by the extraction of RER microsomes through a series of centrifugation processes. Purity of sample was evaluated using western blotting technique. Single channel recordings were done in voltage steps from +50 to -60 mV following incorporation of rat brain RER vesicles into planar bilayers.
Results: We observed a voltage-dependent potassium channel with an approximate conductance of 188 pS. Channel open probability was low at negative voltages, increasing at positive voltages. The channel was blocked by Charybdotoxin but not by Iberiotoxin. Additionally, TRAM-34, a specific KCa3.1 channel blocker, suppressed channel current amplitude and open probability. Western blot analysis revealed specific bands for anti-KCa3.1 antibody, approximately 50 kDa in brain homogenate and RER fraction.
Conclusion: Our study provides strong evidence for the presence of an KCa3.1 channel on the RER membrane in rat brain, exhibiting distinct electro-pharmacological profile compared to plasma membrane and other organelles.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024 Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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