Trimerisation is important for the function of clathrin at the mitotic spindle
Stephen J Royle1, Leon Lagnado
1MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 2QH, UK. S.J.Royle@liverpool.ac.uk
Journal of Cell Science
|September 14, 2006
Summary
Clathrin stabilizes mitotic spindle fibers by acting as a bridge between microtubules. This study confirms clathrin
Area of Science:
- Cell Biology
- Molecular Biology
- Biophysics
Background:
- Clathrin, a protein complex, plays a role in intracellular trafficking and cytoskeletal organization.
- During mitosis, clathrin is implicated in kinetochore fiber stability, a process crucial for accurate chromosome segregation.
Purpose of the Study:
- To investigate the structural requirements of clathrin for its function in stabilizing kinetochore fibers during mitosis.
- To test the proposed 'bridge hypothesis' regarding clathrin's mechanism of action in stabilizing microtubules.
Main Methods:
- Human cells were engineered to express various clathrin heavy chain constructs, replacing the endogenous protein.
- Mutant clathrin proteins were designed to disrupt trimerization or alter the structure of the molecule's legs.
- The ability of these clathrin constructs to rescue mitotic defects in cells depleted of endogenous clathrin was assessed.
Main Results:
- Clathrin constructs unable to form trimers failed to rescue mitotic defects.
- Stunted clathrin molecules with shortened legs could partially restore normal mitosis.
- These findings highlight the importance of clathrin's trimeric structure and spindle-binding domains.
Conclusions:
- Clathrin's trimeric structure is essential for its role in stabilizing kinetochore fibers during mitosis.
- The N-terminal domains of clathrin are critical for interacting with the mitotic spindle, supporting the 'bridge hypothesis'.
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