Ca²⁺-Binding Protein 1 Regulates Hippocampal-dependent Memory and Synaptic Plasticity

Area of Science:

• Neuroscience
• Molecular Biology
• Behavioral Science

Background:

• Calcium-binding protein 1 (CaBP1) is a calcium-sensing protein.
• CaBP1 is structurally similar to calmodulin but primarily expressed in neurons, particularly in the hippocampus.
• The specific function of CaBP1 in the hippocampus remains largely unknown.

Purpose of the Study:

• To investigate the role of CaBP1 in hippocampal-dependent behaviors.
• To elucidate the function of CaBP1 in spatial learning, memory, and neurogenesis.

Main Methods:

• Utilized CaBP1 knockout (C-KO) mice to study the absence of CaBP1.
• Employed Western blot to confirm the absence of caldendrin, the largest CaBP1 splice variant, in C-KO mice.
• Assessed hippocampal-dependent behaviors using Barnes maze, Morris water maze reversal learning, and contextual/cued fear conditioning.
• Quantified adult hippocampal neurogenesis via bromodeoxyuridine labeling.
• Measured hippocampal long-term potentiation (LTP).

Main Results:

• C-KO mice displayed mild deficits in spatial learning and memory in both Barnes and Morris water maze tasks.
• C-KO mice exhibited enhanced freezing responses in contextual fear conditioning but not cued fear conditioning.
• The number of adult-born hippocampal neurons was significantly reduced (approximately 40%) in C-KO mice compared to wild-type (WT) mice.
• Hippocampal long-term potentiation was significantly impaired in C-KO mice.

Conclusions:

• CaBP1 is essential for optimal spatial learning and memory encoding in the hippocampus.
• CaBP1 plays a critical role in regulating hippocampal neurogenesis.
• The findings suggest CaBP1 is required for the cellular mechanisms underlying hippocampal-dependent spatial and fear memory formation.