CPAP is required for cilia formation in neuronal cells

Area of Science:

• Cell Biology
• Neuroscience
• Molecular Biology

Background:

• Primary cilia are microtubule-based organelles involved in cellular signaling.
• Centrosomal P4.1-associated protein (CPAP) regulates centriole length and is implicated in primary microcephaly (MCPH).

Purpose of the Study:

• To investigate the role of CPAP in cilia biogenesis within neuronal cells.
• To determine if CPAP's tubulin-dimer binding activity is essential for its function in ciliogenesis.

Main Methods:

• Utilized a cell-based system monitoring cilia formation in differentiated Cath.a (CAD) cells and primary hippocampal neurons.
• Assessed the effects of wild-type CPAP and a CPAP-377EE mutant (lacking tubulin-dimer binding) on cilia formation and length.
• Investigated CPAP's role by overexpressing wild-type and mutant forms, and through CPAP depletion and rescue experiments.

Main Results:

• CPAP is required for cilia biogenesis in neuronal cells.
• Overexpression of wild-type CPAP promoted cilia formation and increased cilia length.
• A CPAP mutant lacking tubulin-dimer binding inhibited cilia formation and shortened cilia.
• CPAP depletion hindered ciliogenesis, with rescue only observed with wild-type CPAP, not the mutant.

Conclusions:

• CPAP acts as a positive regulator of ciliogenesis in neuronal cells.
• The intrinsic tubulin-dimer binding activity of CPAP is essential for its role in cilia formation and length regulation.