Pathogenic E2K mutation of doublecortin X (DCX) alters microtubule stabilisation and actin filament association

Area of Science:

• Neuroscience
• Cell Biology
• Developmental Biology

Background:

• Mutations in the Doublecortin X (DCX) gene disrupt brain cortical layering.
• Pathogenic mutations often occur in DCX domains mediating microtubule (MT) association.
• The DCX E2K mutation, located in the N-terminus, causes cognitive impairment and pachygyria.

Purpose of the Study:

• To characterize the impact of the DCX E2K mutation on cytoskeletal association and regulation in neuronal cells.
• To investigate how the DCX E2K mutation affects microtubule stability and actin filament interactions.

Main Methods:

• Analysis of DCX E2K mutant protein in neuronal cells.
• Assessment of microtubule bundling and stability using nocodazole-induced depolymerisation assays.
• Measurement of α-tubulin exchange rates.
• Evaluation of DCX E2K association with actin filaments (F-ACT).

Main Results:

• The DCX E2K mutant protein maintains MT interaction and bundling capabilities.
• MTs associated with DCX E2K exhibit reduced sensitivity to nocodazole and slower α-tubulin exchange.
• Increased association of the DCX E2K mutant with the actin filament network was observed.

Conclusions:

• The N-terminus of DCX plays a crucial role in regulating the association and coordination of microtubule and actin filament networks.
• The DCX E2K mutation alters cytoskeletal dynamics, potentially contributing to observed developmental defects.