Alternative splicing variations in mouse CAPS2: differential expression and functional properties of splicing...

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Ca2+-dependent activator protein 2 (CAPS2) is crucial for neurotrophin release.
• Aberrant CAPS2 splicing is linked to autism in humans.
• Mouse CAPS2 splicing and function remain largely uncharacterized.

Purpose of the Study:

• To define mouse CAPS2 gene structure and identify alternative splicing variants.
• To investigate the expression patterns and functions of these variants.
• To understand the role of splicing variations in CAPS2 function.

Main Methods:

• Exon definition and identification of alternative splicing variants in mouse CAPS2.
• Analysis of variant expression in various mouse tissues and developmental stages.
• Biochemical fractionation to determine intracellular localization.
• Assessment of BDNF-releasing activity of different CAPS2 isoforms.

Main Results:

• Identified six mouse CAPS2 splicing variants (CAPS2a-f), with distinct exon deletions.
• A human autism-associated variant (CAPS2Deltaexon3) was not found in mice.
• CAPS2b is brain-exclusive; other isoforms are in brain and non-neural tissues, predominantly in the cerebellum.
• PH domain is critical for membrane association; variants lacking it (CAPS2c, 2f) show altered localization.
• CAPS2c exhibits reduced BDNF release due to PH domain truncation.

Conclusions:

• Mouse CAPS2 exhibits significant splicing diversity, generating long and short forms based on Munc13-1-homologous domain (MHD) presence.
• Splicing variations correlate with expression, localization, and BDNF release.
• The functional implications of short CAPS2 forms, potentially as dominant-negative regulators, require further investigation.