Uncoupling the Excitatory Amino Acid Transporter 2 From Its C-Terminal Interactome Restores Synaptic Glutamate Clearance at Corticostriatal Synapses and Alleviates Mutant Huntingtin-Induced Hypokinesia

• DOI: 10.3389/fncel.2021.792652
• Publication Date: 2022-01-31T05:25:23Z
• Authors: Stefan Hirschberg; Anton Dvorzhak; Seyed M. A. Rasoo...; Svilen Angelov; Marieluise Kirchner; Philipp Mertins; Gilla Lättig-Tünn...; Christoph Harms; Dietmar Schmitz; Rosemarie Grantyn
• Keywords: Synaptic cleft

Rapid removal of glutamate from the sites release is an essential step in excitatory synaptic transmission. However, despite many years research, molecular mechanisms underlying intracellular regulation transport at tripartite synapses have not been fully uncovered. This limits options for pharmacological treatment glutamate-related motor disorders, including Huntington's disease (HD). We therefore investigated possible binding partners transgenic EAAT2 and their alterations under influence mutant huntingtin (mHTT). Mass spectrometry analysis after pull-down striatal YFP-EAAT2 wild-type (WT) mice heterozygote (HET) Q175 mHTT-knock-in identified a total 148 significant (FDR < 0.05) binders to full-length EAAT2. Of them 58 proteins exhibited mHTT-related differences. Most important, 26 mHTT-sensitive cases, protein abundance changed back toward WT levels when expressed C-terminal-truncated instead variant These findings motivated new attempts clarify role astrocytic cortico-basal movement control. Striatal astrocytes HET were targeted by PHP.B vector encoding with different degree C-terminal modification, i.e., EAAT2-S506X (truncation S506), EAAT2-4KR (4 lysine arginine substitutions) or (full-length). The results compared injected tag-only (CTRL). It was found that presence C-terminal-modified transgene (i) increased level native lysates perisynaptic astrocyte processes, (ii) enhanced uptake transduced astrocytes, (iii) stimulated clearance individual corticostriatal synapses, (iv) alleviated hypokinesia (open field indicators initiation). In contrast, over-expression neither facilitated nor locomotion. Together, our support hypothesis preventing abnormal protein-protein interactions could eliminate deficits initiation.