S-Acylation controls functional coupling of BK channel pore-forming α-subunits and β1-subunits
S-Acylation controls functional coupling of BK channel pore-forming α-subunits and β1-subunits
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DOI：
10.1074/jbc.ra119.009065
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发表时间：
2019-08-09
影响因子：
4.8
通讯作者：
Shipston, Michael J.
中科院分区：
文献类型：
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作者：
Duncan, Peter J.;Bi, Danlei;Shipston, Michael J.
在许多组织中，大电导钙和电压激活钾(BK)通道的成孔α-亚基的性质和生理功能通过与调节亚基的功能偶联而被有效地改变。然而，可能控制功能耦合的机制却知之甚少。在这里，我们证明了BK通道成孔α亚基细胞内S0-S1环的S酰化，一种蛋白质翻译后的动态脂质修饰，控制着与调节的β1亚基的功能偶联。在HEK293细胞中，不能被S酰化的α亚基显示细胞表面表达减弱，但通过与β1亚基的共表达恢复了表达。然而，我们也发现，S0-S1环的非酰化通过减弱β1亚基引起的半最大激活电压左移来减少α和β1亚基之间的功能偶联。在同时表达α和β1亚基的小鼠血管平滑肌细胞中，BK通道α亚基被内源性S酰化。我们进一步注意到，在控制S0-S1环的S-酰化的棕榈酰转移酶(Zdhhc23)基因缺失的小鼠中，S-酰化显著减少。Zdhhc23的基因缺失或广谱药物抑制S酰化可减弱内源性BK通道电流，而不依赖于细胞表面α亚基表达的变化。我们认为，S酰化对BK通道的作用依赖于β1亚基的存在。在没有β1亚基的情况下，S酰化促进细胞表面的表达，而当有β1亚基存在时，S酰化控制功能偶联。因此，S酰化提供了一种动态调节与β1亚基的功能偶联的机制，使得对离子通道生理的有条件的、细胞特异性的控制成为可能。
The properties and physiological function of pore-forming alpha-subunits of large conductance calcium- and voltage-activated potassium (BK) channels are potently modified by their functional coupling with regulatory subunits in many tissues. However, mechanisms that might control functional coupling are very poorly understood. Here we show that S-acylation, a dynamic post-translational lipid modification of proteins, of the intracellular S0-S1 loop of the BK channel pore-forming alpha-subunit controls functional coupling to regulatory beta 1-subunits. In HEK293 cells, alpha-subunits that cannot be S-acylated show attenuated cell surface expression, but expression was restored by co-expression with the beta 1-subunit. However, we also found that nonacylation of the S0-S1 loop reduces functional coupling between alpha- and beta 1-subunits by attenuating the beta 1-subunit-induced left shift in the voltage for half-maximal activation. In mouse vascular smooth muscle cells expressing both alpha- and beta 1-subunits, BK channel alpha-subunits were endogenously S-acylated. We further noted that S-acylation is significantly reduced in mice with a genetic deletion of the palmitoyl acyltransferase (Zdhhc23) that controls S-acylation of the S0-S1 loop. Genetic deletion of Zdhhc23 or broad-spectrum pharmacological inhibition of S-acylation attenuated endogenous BK channel currents independently of changes in cell surface expression of the alpha-subunit. We conclude that functional effects of S-acylation on BK channels depend on the presence of beta 1-subunits. In the absence of beta 1-subunits, S-acylation promotes cell surface expression, whereas in its presence, S-acylation controls functional coupling. S-Acylation thus provides a mechanism that dynamically regulates the functional coupling with beta 1-subunits, enabling an additional level of conditional, cell-specific control of ion-channel physiology.