Section on Molecular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
Institute of Molecular Psychiatry, University of Bonn, Bonn, Germany.
Mol Psychiatry. 2018 Nov;23(11):2227-2237. doi: 10.1038/mp.2017.132. Epub 2017 Jul 20.
Genetic variants of Neuregulin 1 (NRG1) and its neuronal tyrosine kinase receptor ErbB4 are associated with risk for schizophrenia, a neurodevelopmental disorder characterized by excitatory/inhibitory imbalance and dopamine (DA) dysfunction. To date, most ErbB4 studies have focused on GABAergic interneurons in the hippocampus and neocortex, particularly fast-spiking parvalbumin-positive (PV+) basket cells. However, NRG has also been shown to modulate DA levels, suggesting a role for ErbB4 signaling in dopaminergic neuron function. Here we report that ErbB4 in midbrain DAergic axonal projections regulates extracellular DA levels and relevant behaviors. Mice lacking ErbB4 in tyrosine hydroxylase-positive (TH+) neurons, but not in PV+ GABAergic interneurons, exhibit different regional imbalances of basal DA levels and fail to increase DA in response to local NRG1 infusion into the dorsal hippocampus, medial prefrontal cortex and dorsal striatum measured by reverse microdialysis. Using Lund Human Mesencephalic (LUHMES) cells, we show that NRG/ErbB signaling increases extracellular DA levels, at least in part, by reducing DA transporter (DAT)-dependent uptake. Interestingly, TH-Cre;ErbB4 mice manifest deficits in learning, spatial and working memory-related behaviors, but not in numerous other behaviors altered in PV-Cre;ErbB4 mice. Importantly, microinjection of a Cre-inducible ErbB4 virus (AAV-ErbB4.DIO) into the mesencephalon of TH-Cre;ErbB4 mice, which selectively restores ErbB4 expression in DAergic neurons, rescues DA dysfunction and ameliorates behavioral deficits. Our results indicate that direct NRG/ErbB4 signaling in DAergic axonal projections modulates DA homeostasis, and that NRG/ErbB4 signaling in both GABAergic interneurons and DA neurons contribute to the modulation of behaviors relevant to psychiatric disorders.
神经调节蛋白 1 (NRG1)及其神经元酪氨酸激酶受体 ErbB4 的遗传变异与精神分裂症风险相关,精神分裂症是一种神经发育障碍,其特征为兴奋性/抑制性失衡和多巴胺 (DA) 功能障碍。迄今为止,大多数 ErbB4 研究都集中在海马体和新皮层的 GABA 能中间神经元上,特别是快速放电的 Parvalbumin 阳性 (PV+)basket 细胞。然而,NRG 也被证明可以调节 DA 水平,提示 ErbB4 信号在多巴胺能神经元功能中起作用。在这里,我们报告中脑 DA 能轴突投射中的 ErbB4 调节细胞外 DA 水平和相关行为。在酪氨酸羟化酶阳性 (TH+)神经元中缺乏 ErbB4 的小鼠,但在 PV+GABA 能中间神经元中不缺乏 ErbB4 的小鼠,表现出基础 DA 水平的不同区域失衡,并且不能响应局部 NRG1 输注到背侧海马体、内侧前额叶皮质和背侧纹状体,通过反向微透析测量。使用 Lund 人中脑 (LUHMES) 细胞,我们表明 NRG/ErbB 信号通过减少 DA 转运体 (DAT)-依赖性摄取来增加细胞外 DA 水平,至少部分如此。有趣的是,TH-Cre;ErbB4 小鼠表现出学习、空间和工作记忆相关行为的缺陷,但在许多其他由 PV-Cre;ErbB4 小鼠改变的行为中没有缺陷。重要的是,将 Cre 诱导的 ErbB4 病毒 (AAV-ErbB4.DIO) 微注射到 TH-Cre;ErbB4 小鼠的中脑,选择性地恢复 DA 能神经元中的 ErbB4 表达,可挽救 DA 功能障碍并改善行为缺陷。我们的结果表明,DA 能轴突投射中的直接 NRG/ErbB4 信号调节 DA 稳态,并且 GABA 能中间神经元和 DA 神经元中的 NRG/ErbB4 信号都有助于调节与精神疾病相关的行为。