Synapse-specific effects of synaptically released zinc: implications for auditory processing

项目摘要 大脑的许多区域，包括皮质、海马体、基底节和边缘结构 富含突触锌。突触锌(以锌离子的形式)被锌装入突触前小泡 转运蛋白3(Znt3)，在突触传递过程中与谷氨酸共同释放。自突触 锌抑制AMPA和NMDA受体--这两种受体介导大部分兴奋性谷氨酸能 大脑中的传递-突触锌可以调节兴奋性突触信号。ZnT3KO小鼠( 缺乏突触锌)表现出一系列认知和感觉障碍，并表现出行为 与自闭症和精神分裂症相关的缺陷。来自人类的越来越多的证据表明 某些锌转运蛋白的突变与主要的神经疾病有关，如 精神分裂症。综上所述，这些发现有力地表明，突触锌信号对 神经元处理。这个项目的目标是了解突触锌是如何促进正常的 神经元功能以及锌信号的中断如何与病理性神经元疾病联系起来。 我们将对这些问题采取三种免费的实验方法。1)使用体外脑 切片准备和光发生刺激范式，我们剖析了突触锌在形成中的作用 皮层微回路中特定突触连接处突触传递的动力学。2)使用 在活体双光子钙成像中，我们评估了突触锌在塑造感觉诱发的 清醒小鼠特定类型听觉皮质神经元的反应。3)使用体外高通量 筛选分析和合理的复合设计方法，我们正在设计新的工具来调节 特定锌转运蛋白的功能。综合起来，这些方法将使我们能够回答 突触锌在脑功能中作用的基本问题及其提供新的机制 对塑造突触和神经加工的内生机制的洞察。

Project Summary Many regions of the brain including the cortex, hippocampus, basal ganglia, and limbic structures are highly enriched with synaptic zinc. Synaptic zinc (as Zn2+) is loaded into presynaptic vesicles by zinc transporter 3 (ZnT3), where it is coreleased with glutamate during synaptic transmission. Since synaptic zinc inhibits AMPA and NMDA receptors – which mediate the majority of excitatory glutamatergic transmission in the brain – synaptic zinc can modulate excitatory synaptic signaling. ZnT3 KO mice (which lack synaptic zinc) display a range of cognitive and sensory impairments and demonstrate behavioral deficits associated with autism and schizophrenia. Mounting evidence from human populations shows that mutations in certain zinc transporters are linked with major neurological disorders such as schizophrenia. Together, these findings strongly suggest that synaptic zinc signaling is important for neuronal processing. The goals of this project are to understand how synaptic zinc contributes to normal neuronal function and how disruptions in zinc signaling are linked to pathological neuronal conditions. We will take three complimentary experimental approaches to these questions. 1) Using ex vivo brain slice preparations and optogenetic stimulation paradigms, we dissect the roles of synaptic zinc in shaping the dynamics of synaptic transmission at specific synaptic connections in cortical microcircuits. 2) Using in vivo 2-photon calcium imaging, we assess the roles of synaptic zinc in shaping the sensory-evoked responses of specific classes of auditory cortical neurons in awake mice. 3) Using in vitro high-throughput screening assays and rational compound design approaches, we are designing novel tools to modulate the function of specific zinc transport proteins. Together these approaches will allow us to answer fundamental questions concerning the role of synaptic zinc in brain function and provide new mechanistic insights into endogenous mechanisms that shape synaptic and neural processing.