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Interaction between Poly(ADP-ribose) and NuMA contributes to mitotic spindle pole assembly
Paul Chang1, Margaret Coughlin, Timothy J Mitchison
1Koch Institute for Integrative Cancer Research, and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. pchang2@mit.edu
Molecular Biology of the Cell
|September 18, 2009
Summary
Poly(ADP-ribose) (pADPr) is crucial for building bipolar spindles. This study reveals pADPr acts as a dynamic cross-linker at spindle poles, essential for proper cell division.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Poly(ADP-ribose) (pADPr) is synthesized by PARP-5a/tankyrase-1 and localizes to mitotic spindle poles.
- pADPr is essential for bipolar spindle assembly, but its precise molecular function remains unclear.
Purpose of the Study:
- To investigate the molecular function of pADPr in spindle pole assembly.
- To elucidate the role of PARP-5a and its modification by pADPr in mitosis.
Main Methods:
- Immunoelectron microscopy (immuno-EM) to localize pADPr at spindle poles.
- Development of a concentrated mitotic HeLa cell lysate system for in vitro spindle pole assembly assays.
- Magnetic bead-based assays using pADPr-coated beads and purified proteins.
Main Results:
- pADPr-coated beads, extended from PARP-5a, induced microtubule aster assembly, indicating a functional role in spindle pole formation.
- PARP-5a activity is significantly higher during mitosis compared to interphase.
- Mitotic PARP-5a captured mitosis-specific pADPr-binding proteins, including NuMA, which directly binds pADPr.
Conclusions:
- pADPr functions as a dynamic cross-linker at spindle poles, mediated by PARP-5a and NuMA.
- This pADPr-mediated cross-linking is critical for the assembly of precisely two spindle poles, ensuring accurate cell division.
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