PCMD-1 stabilizes the PCM scaffold and facilitates centriole separation

Area of Science:

• Cell Biology
• Organelle Dynamics
• Centrosome Biology

Background:

• Centrosomes, composed of centrioles and pericentriolar material (PCM), are vital for cell division.
• Maintaining centrosome stability is essential for spindle pole integrity and bipolar spindle formation.
• The roles of scaffold protein SPD-5 and kinase PLK-1 in PCM formation are known, but PCM stability mechanisms are unclear.

Purpose of the Study:

• To investigate the function of PCMD-1 in establishing and maintaining PCM stability.
• To elucidate the molecular mechanisms underlying PCMD-1's role in centrosome integrity.

Main Methods:

• Analysis of PCMD-1 localization, primarily to centrioles.
• Investigating the interplay between CDK-1, PCMD-1, and PLK-1 phosphorylation.
• In vitro assays to assess PCMD-1 phosphorylation and SPD-5 binding.
• In vivo studies using mutations to evaluate PCM scaffold stability and centriole separation.

Main Results:

• CDK-1 primes PCMD-1 for PLK-1 phosphorylation.
• Mutations disrupting PLK-1 docking sites on PCMD-1 prevent phosphorylation and SPD-5 binding, destabilizing the PCM scaffold.
• PCM scaffold destabilization impairs microtubule-force relay to centrioles, delaying their separation.

Conclusions:

• PCMD-1 is critical for PCM stability and timely centriole separation during PCM disassembly.
• PCMD-1 acts as a seed, initiating scaffold assembly by promoting intrinsic order in the PCM core.
• This ordered propagation ensures the structural integrity of the centrosome scaffold.