Ppp2r1a haploinsufficiency increases excitatory synaptic transmission and decreases spatial learning by impairing endocannabinoid signaling
Yirong Wang, Weicheng Duan, Hua Li, Zhiwei Tang, Ruyi Cai, Shangxuan Cai, Guanghao Deng, Liangpei Chen, Hongyan Luo, Liping Chen, Yulong Li, Jian-Zhi Wang, Bo Xiong, Man Jiang
Yirong Wang, Weicheng Duan, Hua Li, Zhiwei Tang, Ruyi Cai, Shangxuan Cai, Guanghao Deng, Liangpei Chen, Hongyan Luo, Liping Chen, Yulong Li, Jian-Zhi Wang, Bo Xiong, Man Jiang
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Research Article Development Neuroscience

Ppp2r1a haploinsufficiency increases excitatory synaptic transmission and decreases spatial learning by impairing endocannabinoid signaling

Abstract

Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase in the brain. Mutations in PPP2R1A, encoding the scaffolding subunit, are linked to intellectual disability, although the underlying mechanisms remain unclear. This study examined mice with heterozygous deletion of Ppp2r1a in forebrain excitatory neurons (NEX-het-conditional knockout [NEX-het-cKO]). These mice exhibited impaired spatial learning and memory, resembling Ppp2r1a-associated intellectual disability. Ppp2r1a haploinsufficiency also led to increased excitatory synaptic strength and reduced inhibitory synapse numbers on pyramidal neurons. The increased excitatory synaptic transmission was attributed to increased presynaptic release probability, likely due to reduced levels of 2-arachidonoyl glycerol (2-AG). This reduction in 2-AG was associated with increased transcription of monoacylglycerol lipase (MAGL), driven by destabilization of enhancer of zeste homolog 2 (EZH2) in NEX-het-cKO mice. Importantly, the MAGL inhibitor JZL184 effectively restored both synaptic and learning deficits. Our findings uncover an unexpected role of PPP2R1A in regulating endocannabinoid signaling, providing fresh molecular and synaptic insights into the mechanisms underlying intellectual disability.

Authors

Yirong Wang, Weicheng Duan, Hua Li, Zhiwei Tang, Ruyi Cai, Shangxuan Cai, Guanghao Deng, Liangpei Chen, Hongyan Luo, Liping Chen, Yulong Li, Jian-Zhi Wang, Bo Xiong, Man Jiang

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Figure 9

Ppp2r1a haploinsufficiency decreases eCB signaling in excitatory synapses.

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Ppp2r1a haploinsufficiency decreases eCB signaling in excitatory synaps...
(A–F) CB1R activation exerted identical effects in both genotypes (Control, n = 12 neurons; NEX-het-cKO, n = 12 neurons). (A) Schematic of the WIN experiment. (B) Representative EPSCs before and after WIN (2 μM) application. (C) Normalized time-course summary of EPSC amplitude. (D) Unchanged WIN-mediated inhibition of EPSC amplitude. (E) WIN increased EPSC PPRs equally across both genotypes. (F) Normalized PPRs in both genotypes. (G–L) Ppp2r1a haploinsufficiency impaired eCB signaling (Control, n = 13 neurons; NEX-het-cKO, n = 12 neurons). (G) Schematic of AM251 experiment. (H) Representative EPSCs before and after AM251 (5 μM) application. (I) Normalized time-course summary of EPSC amplitude. (J) Effect of AM251 on EPSC amplitude was reduced in NEX-het-cKO mice. (K) AM251-mediated reduction in PPR was blocked in NEX-het-cKO mice. (L) Normalized PPRs in both genotypes. (M–T) GRABeCB2.0 signals were significantly reduced in NEX-het-cKO mice (Control, n = 7 mice; NEX-het-cKO, n = 6 mice). (M) Schematic of GRABeCB2.0 activation. (N) Schematic of viral injection and fiber photometry recordings of GRABeCB2.0 signals in the mPFC. Scale bar: 200 μm. (O and P) Electrical stimulation evoked transient increases in GRABeCB2.0 signals in controls. (O) Heatmap of aligned GRABeCB2.0 signals from individual mice, with stimulation intensities indicated by colors. (P) Average traces of GRABeCB2.0 signals across all controls. (Q and R) Same as O and P but for NEX-het-cKO mice. (S) Input/output plot of GRABeCB2.0 signals versus stimulation intensity. (T) Slope of input/output relationship. Statistical comparisons were performed using 2-tailed unpaired Student’s t test (D, E, K, L, and T), 2-tailed unpaired Student’s t test with Welch’s correction (F), 2-tailed Mann-Whitney test (E, J, and K), 2-tailed paired Student’s t test (E and K), 2-tailed Wilcoxon’s test (E and K), and 2-way ANOVA followed by Bonferroni’s post hoc test (S). All data are presented as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001.