Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
Sci Rep. 2021 May 13;11(1):10256. doi: 10.1038/s41598-021-89820-1.
N-type voltage-gated calcium channels (Ca2.2) are predominantly expressed at presynaptic terminals, and their function is regulated by auxiliary αδ and β subunits. All four mammalian αδ subunits enhance calcium currents through Ca1 and Ca2 channels, and this increase is attributed, in part, to increased Ca expression at the plasma membrane. In the present study we provide evidence that αδ-1, like αδ-2, is recycled to the plasma membrane through a Rab11a-dependent endosomal recycling pathway. Using a dominant-negative Rab11a mutant, Rab11a(S25N), we show that αδ-1 increases plasma membrane Ca2.2 expression by increasing the rate and extent of net forward Ca2.2 trafficking in a Rab11a-dependent manner. Dominant-negative Rab11a also reduces the ability of αδ-1 to increase Ca2.2 expression on the cell-surface of hippocampal neurites. In contrast, αδ-3 does not enhance rapid forward Ca2.2 trafficking, regardless of whether Rab11a(S25N) is present. In addition, whole-cell Ca2.2 currents are reduced by co-expression of Rab11a(S25N) in the presence of αδ-1, but not αδ-3. Taken together these data suggest that αδ subtypes participate in distinct trafficking pathways which in turn influence the localisation and function of Ca2.2.
N 型电压门控钙通道（Ca2.2）主要表达于突触前末梢，其功能受辅助性αδ和β亚基调节。所有四种哺乳动物αδ亚基均增强钙通道 1（Ca1）和钙通道 2（Ca2）的钙电流，这种增加部分归因于质膜上 Ca2.2 表达的增加。在本研究中，我们提供的证据表明，αδ-1 与 αδ-2 一样，通过 Rab11a 依赖性内体再循环途径被再循环到质膜。使用显性负性 Rab11a 突变体 Rab11a（S25N），我们表明 αδ-1 通过以 Rab11a 依赖的方式增加净正向 Ca2.2 转运的速率和程度来增加质膜 Ca2.2 表达。显性负性 Rab11a 还降低了 αδ-1 在海马神经元突表面增加 Ca2.2 表达的能力。相比之下，无论是否存在 Rab11a（S25N），αδ-3 均不能增强快速正向 Ca2.2 转运。此外，在存在 αδ-1 的情况下共表达 Rab11a（S25N）会降低全细胞 Ca2.2 电流。这些数据表明，αδ 亚型参与不同的转运途径，进而影响 Ca2.2 的定位和功能。
