Researchers at the IBS Center for Synaptic Brain Dysfunctions have identified a therapeutic strategy for autism spectrum disorder (ASD) by suppressing the glycine transporter Slc6a20a. By targeting this specific protein, the team successfully restored NMDA receptor (NMDAR) function in mouse models and human cortical organoids, potentially addressing a core mechanism of neurodevelopmental disorders including schizophrenia and intellectual disability.
How does targeting Slc6a20a improve brain function?
NMDARs require both glutamate and glycine to function, acting as essential components for memory, learning, and social interaction. According to Director Kim Eunjoon, previous efforts to boost glycine levels often targeted GlyT1, a transporter found throughout the brain, which led to significant side effects due to its role in breathing and motor control. By contrast, Slc6a20a is expressed primarily in cognition-related regions like the hippocampus and cortex. Suppressing this transporter allows glycine to accumulate where it is needed most, effectively normalizing NMDAR activity without triggering the respiratory or motor complications associated with broader, systemic treatments.
Unlike traditional gene re-expression therapies that aim to replace missing proteins, this approach uses antisense oligonucleotides (ASOs) to modulate existing signaling pathways, which scientists view as a more practical clinical route.
What were the results in autism models?
The research team applied ASO treatment to mouse models carrying SHANK2 and SHANK3 mutations—genetic markers strongly linked to ASD and Phelan-McDermid syndrome. According to the study, the treatment restored NMDAR function and improved behavioral traits, including social interaction and repetitive behaviors. Notably, these improvements occurred in adult mice, a finding that challenges the assumption that neurodevelopmental disorders can only be treated during early “critical periods” of brain development. Further analysis showed that the therapy did not change total protein levels but instead corrected abnormal phosphorylation patterns, suggesting the treatment fine-tunes how existing synapses communicate.
Can these findings translate to human patients?
To evaluate potential human application, the researchers developed cortical organoids using CRISPR gene-editing to replicate SHANK2 and SHANK3 mutations. These organoids exhibited the same NMDAR hypofunction observed in the mouse models. When treated with an ASO targeting the human SLC6A20 gene, the organoid receptor function returned to near-normal levels. According to Director Kim, the consistency between the animal models and human organoid data indicates that this mechanism could serve as a viable framework for treating a spectrum of neuropsychiatric conditions characterized by NMDAR deficiency.
Comparison: Traditional GlyT1 Inhibition vs. Slc6a20a Targeting
| Feature | GlyT1 Inhibition | Slc6a20a Targeting |
|---|---|---|
| Brain Distribution | Widespread | Region-specific (Cortex/Hippocampus) |
| Side Effect Risk | High (Respiratory/Motor) | Low (Targeted) |
Frequently Asked Questions
What is the role of NMDA receptors in autism?
NMDARs are critical for synaptic signaling. Impaired function of these receptors is associated with social, cognitive, and repetitive behavioral issues found in autism spectrum disorder and other neurological conditions.
How long do the effects of the ASO treatment last?
In mouse studies, a single administration of the ASO remained effective for at least eight weeks without detectable adverse effects, according to the IBS Center for Synaptic Brain Dysfunctions.
Is this treatment currently available for humans?
No. While the results in human cortical organoids are promising, the strategy is currently in the research phase and has not yet moved to human clinical trials.
Follow the latest updates from the IBS Center for Synaptic Brain Dysfunctions to track the progress of this research as it moves toward clinical development.
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