Laboratory of Molecular and Cellular Neurobiology, National Institute of Mental Health, National Institutes of Health, 35 Convent Drive, Room 3A:209, Bethesda, MD, 20892, USA.
University of Southern California Graduate Program, Los Angeles, CA, 90033, USA.
Neurochem Res. 2020 Jun;45(6):1410-1419. doi: 10.1007/s11064-019-02939-6. Epub 2020 Jan 7.
Amphetamines and amphetamine-derivatives elevate neurotransmitter concentrations by competing with endogenous biogenic amines for reuptake. In addition, AMPHs have been shown to activate endocytosis of the dopamine transporter (DAT) which further elevates extracellular dopamine (DA). We previously found that the biochemical cascade leading to this cellular process involves entry of AMPH into the cell through the DAT, stimulation of an intracellular trace amine-associated receptor, TAAR1, and activation of the small GTPase, RhoA. We also showed that the neuronal glutamate transporter, EAAT3, undergoes endocytosis via the same cascade in DA neurons, leading to potentiation of glutamatergic inputs. Since AMPH is a transported inhibitor of both DAT and the norepinephrine transporter (NET), and EAAT3 is also expressed in norepinephrine (NE) neurons, we explored the possibility that this signaling cascade occurs in NE neurons. We found that AMPH can cause endocytosis of NET as well as EAAT3 in NE neurons. NET endocytosis is dependent on TAAR1, RhoA, intracellular calcium and CaMKII activation, similar to DAT. However, EAAT3 endocytosis is similar in all regards except its dependence upon CaMKII activation. RhoA activation is dependent on calcium, but not CaMKII, explaining a divergence in AMPH-mediated endocytosis of DAT and NET from that of EAAT3. These data indicate that AMPHs and other TAAR1 agonists can affect glutamate signaling through internalization of EAAT3 in NE as well as DA neurons.
安非他命和苯丙胺类通过与内源性生物胺竞争再摄取来提高神经递质浓度。此外，已经证明 AMPHs 可以激活多巴胺转运体（DAT）的内吞作用，从而进一步提高细胞外多巴胺（DA）的水平。我们之前发现，导致这一细胞过程的生化级联反应包括 AMPH 通过 DAT 进入细胞，刺激细胞内痕量胺相关受体 TAAR1，并激活小 GTP 酶 RhoA。我们还表明，神经元谷氨酸转运体 EAAT3 通过 DA 神经元中的相同级联反应发生内吞作用，导致谷氨酸能传入的增强。由于 AMPH 是 DAT 和去甲肾上腺素转运体（NET）的转运抑制剂，并且 EAAT3 也在去甲肾上腺素（NE）神经元中表达，因此我们探讨了这种信号级联反应是否发生在 NE 神经元中的可能性。我们发现 AMPH 可以导致 NE 神经元中的 NET 和 EAAT3 内吞作用。NET 内吞作用依赖于 TAAR1、RhoA、细胞内钙和 CaMKII 激活，与 DAT 相似。然而，EAAT3 内吞作用在所有方面都相似，除了依赖于 CaMKII 激活。RhoA 激活依赖于钙，但不依赖于 CaMKII，这解释了 AMPH 介导的 DAT 和 NET 内吞作用与 EAAT3 内吞作用的分歧。这些数据表明，安非他命和其他 TAAR1 激动剂可以通过内吞作用影响 NE 以及 DA 神经元中的 EAAT3，从而影响谷氨酸信号。
