Carboxypeptidase E conditional knockout mice exhibit learning and memory deficits and neurodegeneration

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Carboxypeptidase E (CPE) is a multifunctional protein with known neuroprotective roles.
• Previous research indicated CPE involvement in learning and memory, but its specific functions within neurons remained unclear.

Purpose of the Study:

• To investigate the specific functions of Carboxypeptidase E (CPE) in neurons.
• To determine the effects of conditional neuronal CPE knockout on learning, memory, and brain structure.

Main Methods:

• Utilized a Camk2a-Cre system for conditional knockout of CPE in mouse neurons.
• Conducted behavioral tests (open field, object recognition, Y-maze, fear conditioning) on wild-type, CPE^flox/-, and CPE^flox/flox mice.
• Performed histological analyses, including immunostaining for neurogenesis markers and protein expression (MAP2, GFAP, TrkB).

Main Results:

• Conditional neuronal CPE knockout (CPE^flox/flox) resulted in impaired learning and memory.
• Complete degeneration of the subiculum (Sub) region was observed in CPE^flox/flox mice.
• Reduced neurogenesis in the dentate gyrus, downregulated TrkB phosphorylation, and decreased MAP2/GFAP expression were noted in the hippocampus and prefrontal cortex.

Conclusions:

• Specific knockout of neuronal CPE induces central nervous system dysfunction in mice.
• Neuronal CPE plays a critical role in maintaining learning, memory, hippocampal structure, and neurogenesis.
• These findings highlight the importance of neuronal CPE in cognitive function and brain health.