Hippocampal astrocytic neogenin regulating glutamate uptake, a critical pathway for preventing epileptic response.

Abstract

Epilepsy, a common neurological disorder, is featured with recurrent seizures. Its underlying pathological mechanisms remain elusive. Here, we provide evidence for loss of neogenin (NEO1), a coreceptor for multiple ligands, including netrins and bone morphological proteins, in the development of epilepsy. NEO1 is reduced in hippocampi from patients with epilepsy based on transcriptome and proteomic analyses. Neo1 knocking out (KO) in mouse brains displays elevated epileptiform spikes and seizure susceptibility. These phenotypes were undetectable in mice, with selectively depleted NEO1 in excitatory (NeuroD6-Cre+) or inhibitory (parvalbumin+) neurons, but present in mice with specific hippocampal astrocytic Neo1 KO. Additionally, neurons in hippocampal dentate gyrus, a vulnerable region in epilepsy, in mice with astrocyte-specific Neo1 KO show reductions in inhibitory synaptic vesicles and the frequency of miniature inhibitory postsynaptic current(mIPSC), but increase of the duration of miniature excitatory postsynaptic current and tonic NMDA receptor currents, suggesting impairments in both GABAergic transmission and extracellular glutamate clearance. Further proteomic and cell biological analyses of cell-surface proteins identified GLAST, a glutamate-aspartate transporter that is marked reduced in Neo1 KO astrocytes and the hippocampus. NEO1 interacts with GLAST and promotes GLAST surface distribution in astrocytes. Expressing NEO1 or GLAST in Neo1 KO astrocytes in the hippocampus abolishes the epileptic phenotype. Taken together, these results uncover an unrecognized pathway of NEO1-GLAST in hippocampal GFAP+ astrocytes, which is critical for GLAST surface distribution and function, and GABAergic transmission, unveiling NEO1 as a valuable therapeutic target to protect the brain from epilepsy.

• Authors: Dong Sun, Zhi-Bing Tan, Xiang-Dong Sun, Zhi-Peng Liu, Wen-Bing Chen, Leena Milibari, Xiao Ren, Ling-Ling Yao, Daehoon Lee, Chen Shen, Jin-Xiu Pan, Zhi-Hui Huang, Lin Mei, Wen-Cheng Xiong
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 118 Issue 16 (04 20 2021) ISSN: 1091-6490 [Electronic] United States
• PMID: 33850017 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Excitatory Amino Acid Transporter 1
• Excitatory Amino Acid Transporter 2
• Membrane Proteins
• neogenin
• Glutamic Acid

Topics

• Animals
• Astrocytes (metabolism, physiology)
• Biological Transport (physiology)
• Epilepsy (physiopathology, prevention & control)
• Excitatory Amino Acid Transporter 1 (metabolism)
• Excitatory Amino Acid Transporter 2 (metabolism)
• Female
• Glutamic Acid (metabolism)
• Hippocampus (metabolism)
• Male
• Membrane Proteins (metabolism, physiology)
• Mice
• Mice, Inbred C57BL
• Mice, Knockout
• Neurons (metabolism)
• Seizures (metabolism)
• Signal Transduction
• Synaptic Potentials (physiology)