Chloride homeostasis in neuronal compartments under acute metabolic stress

在神经元中，跨质膜以及跨细胞内膜的氯离子梯度具有多种细胞功能，例如调节兴奋性、神经递质释放以及pH和体积调节。氯离子浓度通过各种离子通道和次级活性转运蛋白的相互作用来确定，所述次级活性转运蛋白将阴离子浓度与Na+、K+和H+的电化学梯度偶联。因此，预计代谢应激期间[Na+]、[K+]和[H+]的变化会改变细胞内[Cl-]。我们将研究正常条件下和代谢应激下神经元索马和神经元延伸以及细胞内细胞器中的氯稳态。我们将使用荧光寿命成像显微镜与基于喹啉的荧光指示剂或荧光成像与遗传编码的氯化物传感器，以及电生理分析的阴离子选择性通道的反转电位。Cl-离子在调节谷氨酸能神经元突触囊泡中谷氨酸积累中起重要作用，我们将研究谷氨酸和氯离子浓度如何相互调节。Cl-/H+交换器连接[Cl-]和pH值的内涵体，我们将分析如何pH调节和氯稳态交织在这些细胞器在正常条件下，以及在能量限制。

In neurons, chloride gradients across the plasma membrane as well as across intracellular membranes serve multiple cellular functions, such as regulation of excitability, neurotransmitter release and pH and volume regulation. Chloride concentrations are determined via the interplay of various ion channels and secondary active transporters that couple anion concentrations to the electrochemical gradients of Na+, K+ and H+. Changes in [Na+], [K+] and [H+] during metabolic stress are thus expected to alter intracellular [Cl-]. We will study the chloride homeostasis in the neuronal soma and in neuronal extensions as well as in intracellular organelles under normal conditions and under metabolic stress. We will use fluorescence lifetime imaging microscopy with quinolinium-based fluorescent indicators or fluorescence imaging with genetically encoded chloride sensors as well as the electrophysiological analysis of reversal potentials of anion-selective channels. Cl- ions play an important role in regulating glutamate accumulation in synaptic vesicles of glutamatergic neurons, and we will study how glutamate and chloride concentrations modify each other. Cl-/H+ exchangers link [Cl-] and pH in endosomes, and we will analyze how pH regulation and chloride homeostasis are intertwined in these organelles under normal conditions as well as under energy restriction.