This study reports that genetic inhibition of the ESCRT-I component TSG101 protects against persistent NMDAR hypofunction and restores synaptic homeostasis in a primary hippocampal neuron model of schizophrenia produced by sub-chronic phencyclidine (PCP) exposure. The work is presented as a preprint and has not been peer reviewed.
N-methyl-D-aspartate receptor (NMDAR) hypofunction is considered a central mechanism in the pathophysiology of schizophrenia. The authors note that attempts at direct NMDAR potentiation have shown limited clinical benefit, potentially because such approaches do not address underlying deficits in receptor trafficking and surface stability. The endosomal sorting complexes required for transport (ESCRT) machinery regulates the lysosomal fate of internalised membrane proteins; however, its role in maintaining synaptic receptor homeostasis during glutamatergic dysfunction was not well defined prior to this work.
The investigators used sub-chronic exposure to phencyclidine (PCP), a non-competitive NMDAR antagonist widely used to model NMDAR hypofunction and schizophrenia-like phenotypes, in primary hippocampal neuronal cultures. This exposure produced persistent functional alterations consistent with NMDAR hypofunction and network dysregulation.
Sub-chronic PCP exposure induced persistent NMDAR hypofunction, impaired GABAergic transmission, and a collapse of excitation/inhibition (E/I) balance in the cultured hippocampal neurons. These deficits encompassed changes at synaptic and network levels, producing reduced inhibitory tone and abnormal excitatory activity.
Genetic inhibition (knockdown) of the ESCRT-I component TSG101 prevented the deficits induced by PCP exposure. TSG101 knockdown enabled functional recovery after PCP washout, indicating that modulation of ESCRT-I can stabilise synaptic function once the antagonist is removed. The study frames ESCRT-I inhibition as protective against the persistent consequences of NMDAR antagonism in this cellular model.
TSG101 knockdown increased surface expression of functional NMDARs and GABAA receptors in the neuronal cultures. Importantly, these changes occurred without altering receptor pharmacology or intrinsic biophysical properties, implying that the intervention acts on receptor trafficking or membrane stability rather than on receptor gating or conductance.
At the network scale, TSG101 knockdown restored inhibitory tone, normalised excitatory activity, and stabilised the E/I balance disrupted by PCP exposure. These network effects align with the observed increases in surface receptor expression and indicate functional consequences that extend beyond single-synapse changes to circuit-level activity in vitro.
TSG101 knockdown also rescued molecular and signalling deficits induced by PCP. Specifically, the intervention restored levels of PSD-95 and brain-derived neurotrophic factor (BDNF), re-established ERK1/2 signalling, and re-enabled activity-dependent nuclear translocation of Fos-like (Fos-L) proteins. The authors interpret these results as consistent with reactivation of transcriptional plasticity and broader synaptic stabilisation.
Based on these findings, the authors propose that ESCRT-I acts as a regulator of synaptic stability and that endosomal sorting pathways may represent a potential therapeutic target for addressing receptor trafficking deficits associated with NMDAR hypofunction in schizophrenia. The data suggest that modifying receptor fate after internalisation can influence surface receptor availability, inhibitory/excitatory balance, and activity-dependent signalling.
The report is a preprint and has not been certified by peer review. The summary does not provide detailed experimental parameters, such as the exact PCP dosing regimen, timelines, quantitative effect sizes, or the specific methods used for TSG101 knockdown; those methodological details and full data should be consulted in the full manuscript. The authors disclosed a competing interest for one author who is a shareholder and CEO of a biotechnology company; the manuscript states that all authors have no other conflicts related to the publication.
Overall, the study presents cellular-level evidence that interference with ESCRT-I can prevent and reverse synaptic and network disturbances produced by pharmacological NMDAR blockade, highlighting endosomal sorting as a mechanistic link between receptor trafficking and synaptic homeostasis in a model relevant to schizophrenia.