Rac1 and Rac3 GTPases and TPC2 are required for axonal outgrowth and migration of cortical interneurons

Area of Science:

• Neuroscience
• Cell Biology
• Developmental Biology

Background:

• Rho GTPases, including Rac1 and Rac3, are vital for cellular signaling and processes.
• Cortical interneurons regulate the balance of excitation and inhibition in the brain.
• Rac1 and Rac3 are essential for the proper development of cortical interneurons.

Purpose of the Study:

• To investigate the role of Rac1 and Rac3 in cortical interneuron development.
• To explore the impact of Rac1 and Rac3 ablation on interneuron migration and axon growth.
• To examine the involvement of the TPC2 ion channel in Rac1/Rac3-deficient interneurons.

Main Methods:

• Genetic ablation of Rac1 and Rac3 in murine cortical interneurons.
• Analysis of centrosome, Golgi, and lysosome positioning.
• Assessment of interneuron migration and axon growth.
• Investigation of Two-Pore Channel 2 (TPC2) expression and localization.

Main Results:

• Rac1 and Rac3 ablation severely reduces mature interneuron numbers due to cell cycle and growth cone defects.
• Absence of Rac1 and Rac3 perturbs organelle positioning, impairing interneuron migration and axon growth.
• TPC2 expression and localization are altered in Rac1/Rac3-deficient interneurons.
• TPC2 inhibition exacerbates axonal growth and migration deficits.

Conclusions:

• Rac1 and Rac3 are critical for maintaining organelle positioning essential for interneuron migration and axon growth.
• TPC2 plays a significant role in mediating the severe developmental defects observed in Rac1/Rac3-deficient interneurons.
• Targeting TPC2 may offer therapeutic potential for neurological disorders involving interneuron dysfunction.