Antioxidant Behavioural Phenotype in the Immp2l Gene Knock-Out Mouse

Area of Science:

• Neuroscience
• Genetics
• Biochemistry

Background:

• Mitochondrial dysfunction is linked to autism spectrum disorder (ASD).
• The Inner mitochondrial membrane protein 2-like (IMMP2L) gene is associated with autism inheritance.
• Previous studies suggested oxidative stress links IMMP2L and ASD, but the biological basis remains unclear.

Purpose of the Study:

• To investigate the behavioral and biochemical consequences of IMMP2L loss-of-function.
• To determine if oxidative stress is involved in the behavioral changes observed in the absence of IMMP2L.
• To assess the therapeutic potential of antioxidants for IMMP2L-associated behaviors.

Main Methods:

• Development of a novel Immp2l knockout (KO) mouse model lacking Immp2l peptidase activity.
• Behavioral testing, including response to auditory stimuli and amphetamine-induced locomotion.
• Measurement of reactive oxygen species (ROS) levels and assessment of oxidative stress phenotypes.
• Evaluation of the effects of the antioxidant MitoQ on behavior and ROS levels.

Main Results:

• Immp2l KO mice did not exhibit core ASD behavioral symptoms but showed increased auditory stimulus-driven behavior and amphetamine-induced locomotion.
• Contrary to expectations, Immp2l KO mice displayed significantly lowered ROS levels and no oxidative stress-related phenotypes.
• The antioxidant MitoQ did not affect the observed behavioral changes in Immp2l KO mice.
• Electron microscopy confirmed no age-related ataxia or neurodegeneration in Immp2l KO mice, which were also fully fertile.

Conclusions:

• Behavioral changes in Immp2l KO mice are associated with an antioxidant-like phenotype (lowered ROS) rather than increased oxidative stress.
• Antioxidant treatments are unlikely to be effective for behaviors directly resulting from Immp2l/IMMP2L loss-of-function.
• The behavioral impact of IMMP2L intragenic deletion-associated truncations requires further investigation.