Differential distribution of Ca²⁺-activated potassium channel β4 subunit in rat brain: Immunolocalization in neuronal mitochondria

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• 作者：M. Piwonska ; E. Wilczek ; A. Szewczyk ; G.M. Wilczynski
• 关键词：BK_Ca channels ; regulatory β ; subunit ; CNS ; mitochondrial inner membrane
• 刊名：Neuroscience
• 出版年：2008
• 出版时间：2 May 2008
• 年：2008
• 卷：153
• 期：2
• 页码：446-460
• 全文大小：3311 K

文摘

Large conductance Ca²⁺-activated potassium channels (BK_Ca channels) are expressed in the plasma membrane of various cell types. Interestingly, recent studies provided evidence for the existence of BK_Ca channels also in mitochondria. However, the molecular composition of these channels as well as their cellular and tissue distribution is still unknown. The goal of the present study was to find a candidate for the regulatory component of the mitochondrial large conductance calcium activated potassium (mitoBK_Ca) channel in neurons. A combined approach of Western blot analysis, high-resolution immunofluorescence and immunoelectron microscopy with the use of antibodies directed against four distinct β subunits demonstrated the presence of the BK_Ca channel β4 subunit (KCNMB4) in the inner membrane of neuronal mitochondria in the rat brain and cultured neurons. Within the cell, the expression of β4 subunit was restricted to a subpopulation of mitochondria. The analysis of β4 subunit distribution throughout the brain revealed that the highest expression levels occur in the thalamus and the brainstem. Our results suggest that β4 subunit is a regulatory component of mitochondrial BK_Ca channels in neurons. These findings may support the perspectives for the neuroprotective role of mitochondrial BK_Ca channel in specific brain structures.