Self-assembly of pericentriolar material in interphase cells lacking centrioles

Area of Science:

• Cell Biology
• Cytoskeleton Dynamics
• Molecular Cell Biology

Background:

• The centrosome, the primary microtubule-organizing center (MTOC) in animal cells, consists of centrioles and pericentriolar material (PCM).
• Centrosome assembly involves PCM binding to centrioles, PCM self-association, and dynein-mediated transport.
• The self-assembly properties of PCM components in interphase cells, independent of centrioles, are not well understood.

Purpose of the Study:

• To investigate the centriole-independent self-assembly of interphase pericentriolar material (PCM).
• To determine the key PCM components and conditions necessary for forming an acentriolar MTOC.
• To understand how motor and microtubule dynamics influence PCM self-organization.

Main Methods:

• Experimental manipulation of centriole number via PLK4 depletion/inhibition.
• Biochemical assays to identify essential PCM self-assembly components (γ-tubulin, pericentrin, CDK5RAP2, ninein).
• Modeling and live-cell imaging to observe MTOC formation and microtubule organization.

Main Results:

• Dynein-based transport and self-clustering of PCM proteins can form a compact, acentriolar MTOC that organizes microtubules, even without centrioles.
• Specific PCM components, including γ-tubulin, pericentrin, CDK5RAP2, and ninein, are crucial for interphase PCM self-assembly.
• PCM self-organization into a compact MTOC is inhibited by Golgi-recruitment or randomly organized microtubules, but can be induced by linking CAMSAP2 to motors, requiring pericentrin for compaction.

Conclusions:

• Interphase PCM possesses self-assembly capabilities, forming functional MTOCs independently of centrioles.
• PCM self-organization is a regulated process sensitive to cellular motor and microtubule organization.
• This study reveals novel insights into the fundamental mechanisms of MTOC assembly and microtubule organization in animal cells.