Meprin β Modulates Brevican Proteolysis Impairing Neural Plasticity and Memory Formation

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• Meprin β is a metalloprotease involved in various physiological processes, including brain functions.
• Its specific roles in the brain beyond amyloid β generation are not fully understood.
• Understanding meprin β's broader neurological functions is crucial for comprehending neural circuit dynamics.

Purpose of the Study:

• To investigate the broader functions of meprin β in the brain, particularly its impact on cognitive functions and neural plasticity.
• To explore the molecular mechanisms underlying meprin β's effects on neuronal function.
• To identify potential mediators linking meprin β activity to observed neurological deficits.

Main Methods:

• Utilized a mouse model with neuronal overexpression of meprin β in the cortex and hippocampus.
• Conducted behavioral assessments using the Morris' Water Maze test.
• Performed electrophysiological recordings (long-term potentiation - LTP) in hippocampal slices.
• Analyzed protein expression via western blotting and identified proteolytic substrates using N-terminomics.

Main Results:

• Meprin β overexpression led to impaired cognitive functions in behavioral tests.
• Electrophysiology revealed impaired LTP and increased neuronal excitability in meprin β-overexpressing mice.
• No significant changes were observed in NMDA or AMPA receptor expression.
• N-terminomics identified brevican as a meprin β substrate, suggesting its role in mediating the observed effects.

Conclusions:

• Meprin β plays a significant role in regulating cognitive functions and synaptic plasticity in the brain.
• The metalloprotease meprin β influences neuronal excitability and LTP, potentially via modulation of brevican.
• These findings highlight meprin β as a key player in neurological processes and suggest its involvement in learning and memory mechanisms.