Su Feifei, Pfundstein Grant, Sah Saroj, Zhang Shuyue, Keable Ryan, Hagan D Walker, Sharpe Laura J, Clemens Kelly J, Begg Denovan, Phelps Edward A, Brown Andrew J, Leshchyns'ka Iryna, Sytnyk Vladimir
School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, New South Wales, Australia.
J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, USA.
J Neurochem. 2025 Jan;169(1):e16279. doi: 10.1111/jnc.16279.
Neuronal growth regulator 1 (NEGR1) is a synaptic plasma membrane localized cell adhesion molecule implicated in a wide spectrum of psychiatric disorders. By RNAseq analysis of the transcriptomic changes in the brain of NEGR1-deficient mice, we found that NEGR1 deficiency affects the expression of the Gad2 gene. We show that glutamic acid decarboxylase 65 (GAD65), the Gad2 - encoded enzyme synthesizing the inhibitory neurotransmitter GABA on synaptic vesicles, accumulates non-synaptically in brains of NEGR1-deficient mice. The density of non-synaptic GAD65 accumulations is also increased in NEGR1 deficient cultured hypothalamic neurons, and this effect is rescued by re-expression of NEGR1. By using a novel biosensor of the plasma membrane attachment of GAD65, we demonstrate that GAD65 attaches to the plasma membrane. NEGR1 promotes palmitoylation-dependent clearance of GAD65 from the plasma membrane and targeting of GAD65 to plasma membrane-derived endocytic vesicles. In NEGR1 deficient cultured hypothalamic neurons, the synaptic and extrasynaptic levels of the plasma membrane attached GAD65 are increased, and the synaptic levels of GABA are reduced. NEGR1-deficient mice are characterized by reduced body weight, lower GABAergic synapse densities in the arcuate nucleus, and blunted responsiveness to the reinforcing effects of food rewards. Our results indicate that abnormalities in synaptic GABA synthesis can contribute to brain disorders associated with abnormal expression of NEGR1 in humans.
神经元生长调节因子1（NEGR1）是一种定位于突触质膜的细胞粘附分子，与多种精神疾病有关。通过对NEGR1基因缺陷小鼠大脑转录组变化的RNA测序分析，我们发现NEGR1基因缺陷会影响Gad2基因的表达。我们发现，谷氨酸脱羧酶65（GAD65），即由Gad2基因编码的在突触小泡上合成抑制性神经递质GABA的酶，在NEGR1基因缺陷小鼠的大脑中非突触性地积累。在NEGR1基因缺陷的培养下丘脑神经元中，非突触性GAD65积累的密度也增加，而重新表达NEGR1可挽救这种效应。通过使用一种新型的GAD65质膜附着生物传感器，我们证明GAD65可附着于质膜。NEGR1促进GAD65从质膜的棕榈酰化依赖性清除，并将GAD65靶向质膜衍生的内吞小泡。在NEGR1基因缺陷的培养下丘脑神经元中，质膜附着的GAD65的突触和突触外水平增加，而GABA的突触水平降低。NEGR1基因缺陷小鼠的特征是体重减轻、弓状核中GABA能突触密度降低以及对食物奖励强化作用的反应迟钝。我们的结果表明，突触GABA合成异常可能导致与人类NEGR1异常表达相关的脑部疾病。
