Sevoflurane Acts on Ubiquitination-Proteasome Pathway to Reduce Postsynaptic Density 95 Protein Levels in Young Mice
Han Lu1, Ning Liufu, Yuanlin Dong
1From the Department of Anesthesiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China (H.L., B.Y.); Department of Anesthesia, Critical Care and Medicine (H.L., N.L., Y.D., G.X., Y.Z., L.S., Z.X.) and Massachusetts General Hospital Biostatistics Center (H.Z.), Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts; Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China (N.L.); First Affiliated Hospital, Anhui Medical University, Hefei, China (G.X.); School of Medicine and Health Sciences, George Washington University, Washington, D.C. (L.S.); and Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts (S.G.S.).
Insights
Sevoflurane anesthesia reduces postsynaptic density 95 protein levels by promoting its degradation via the ubiquitination-proteasome pathway. This leads to cognitive impairment in young mice, highlighting anesthesia neurotoxicity risks.
Area of Science:
- Neuroscience
- Anesthesiology
- Molecular Biology
Background:
- Pediatric exposure to anesthesia and surgery is linked to cognitive impairment risks.
- Sevoflurane, a common pediatric anesthetic, reduces postsynaptic density 95 (PSD-95) protein levels.
- The mechanisms behind sevoflurane's effect on PSD-95 and subsequent cognitive outcomes are largely unknown.
Purpose of the Study:
- To investigate if sevoflurane influences the ubiquitination-proteasome pathway to degrade PSD-95.
- To determine the impact of sevoflurane on PSD-95 levels and cognitive function in young mice.
Main Methods:
- Young mice received sevoflurane anesthesia, and PSD-95 levels (mRNA, protein, ubiquitination) were analyzed in neurons, synaptosomes, and hippocampus.
- Cognitive function was assessed using the Morris water maze.
- Proteasome and E3 ligase inhibitors (MG132, Nutlin-3) were used to study molecular interactions.
Main Results:
- Sevoflurane decreased PSD-95 protein and ubiquitinated levels, but not mRNA, in brain tissues.
- Inhibitors MG132 and Nutlin-3 counteracted sevoflurane's effects on PSD-95.
- Sevoflurane enhanced the interaction between MDM2 and PSD-95, and inhibitors ameliorated cognitive deficits.
Conclusions:
- Sevoflurane promotes PSD-95 degradation via the ubiquitination-proteasome pathway, leading to reduced PSD-95 levels and cognitive impairment.
- These findings elucidate a mechanism of anesthesia-induced neurotoxicity in the developing brain.
- Targeting the ubiquitination-proteasome pathway may offer strategies to mitigate anesthesia-related cognitive deficits.
Background:
Children with multiple exposures to anesthesia and surgery may have an increased risk of developing cognitive impairment. Sevoflurane, a commonly used anesthetic in children, has been reported to decrease levels of postsynaptic density 95 protein. However, the upstream mechanisms and downstream consequences of the sevoflurane-induced reduction in postsynaptic density 95 protein levels remains largely unknown. We therefore set out to assess whether sevoflurane acts on ubiquitination-proteasome pathway to facilitate postsynaptic density 95 protein degradation.
Methods:
Six-day-old wild-type mice received anesthesia with 3% sevoflurane 2 h daily for 3 days starting on postnatal day 6. We determined the effects of the sevoflurane anesthesia on mRNA, protein and ubiquitinated levels of postsynaptic density 95 protein in neurons, and synaptosomes and hippocampus of young mice. Cognitive function in the mice was determined at postnatal day 31 by using a Morris water maze. Proteasome inhibitor MG132 and E3 ligase mouse double mutant 2 homolog inhibitor Nutlin-3 were used for the interaction studies.
Results:
The sevoflurane anesthesia decreased protein, but not mRNA, levels of postsynaptic density 95, and reduced ubiquitinated postsynaptic density 95 protein levels in neurons, synaptosomes, and hippocampus of young mice. Both MG132 and Nutlin-3 blocked these sevoflurane-induced effects. Sevoflurane promoted the interaction of mouse double mutant 2 homolog and postsynaptic density 95 protein in neurons. Finally, MG132 and Nutlin-3 ameliorated the sevoflurane-induced cognitive impairment in the mice.
Conclusions:
These data suggest that sevoflurane acts on the ubiquitination-proteasome pathway to facilitate postsynaptic density 95 protein degradation, which then decreases postsynaptic density 95 protein levels, leading to cognitive impairment in young mice. These studies would further promote the mechanistic investigation of anesthesia neurotoxicity in the developing brain.
