Related Experiment Video
Updated: Jun 13, 2026
09:38
Identification of Nucleolar Factors During HIV-1 Replication Through Rev Immunoprecipitation and Mass Spectrometry
Published on: June 26, 2019
Nucleophosmin/B23 inhibits Eg5-mediated microtubule depolymerization by inactivating its ATPase activity
Guoxing Wang1, Xiang Gao, Yun Huang
1Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.
The Journal of Biological Chemistry
|April 21, 2010
Summary
Nucleophosmin/B23 protein regulates microtubule dynamics by interacting with and inhibiting Eg5 motor protein activity. This finding reveals a novel role for B23 in controlling cell proliferation through microtubule polymerization.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Nucleophosmin/B23 is a key nucleolar protein involved in cell growth and proliferation.
- Its role in regulating microtubule dynamics remains largely unexplored.
Purpose of the Study:
- To investigate the interaction between Nucleophosmin/B23 and Eg5.
- To elucidate the function of Nucleophosmin/B23 in regulating microtubule dynamics via Eg5.
Main Methods:
- Co-immunoprecipitation assays to confirm B23-Eg5 interaction.
- In vitro and in vivo assays to assess the effect of B23 on Eg5 activity and microtubule polymerization.
- ATPase assays to determine the inhibitory mechanism.
Main Results:
- Nucleophosmin/B23 directly interacts with Eg5 in the cytosol.
- The DNA/RNA binding domain of B23 and the motor domain of Eg5 are crucial for this interaction.
- B23 promotes microtubule polymerization by acting as an upstream regulator of Eg5.
- B23 inhibits Eg5 ATPase activity, thereby regulating microtubule dynamics.
Conclusions:
- Nucleophosmin/B23 plays a significant role in regulating microtubule dynamics.
- B23 directly modulates Eg5 activity, impacting microtubule polymerization and cellular processes.
- This study uncovers a novel mechanism by which a nucleolar protein influences cytoplasmic events crucial for cell proliferation.
Related Concept Videos
01:45Destabilization of Microtubules
The destabilization of microtubules can occur during different stages of the microtubule lifecycle, such as nucleation or elongation. It can take place at either end of the microtubule or in the microtubule lattices as a whole. The lifespan of individual microtubules within a cell varies according to the cell type and stage of the cell cycle. During interphase, the lifespan of the microtubule is about 30 minutes, while during cell division, it is about 15 minutes. In axonal microtubules of...
01:10Drugs that Destabilize Microtubules
Microtubules are dynamic structures and can be regulated by microtubule targeting agents (MTAs). Microtubule destabilizing drugs are a class of MTAs that destabilize and prevent microtubules' polymerization. Both natural and synthetic chemicals can be found under this class of drugs. Vincristine and vinblastine, two vinca alkaloids, and colchicine were among the first to be discovered. These drugs can affect cells in various ways, either by inducing a change in cell morphology, preventing...
01:15Drugs that Stabilize Microtubules
Microtubules are dynamic structures that undergo cycles of catastrophe and rescue. The microtubules play a central role in cell division by forming the spindle apparatus for segregating the chromosomes. This makes them ideal targets for regulating dividing cells in tumors and malignant cancer cells. Microtubule stabilizing drugs help stabilize the microtubule formation and promote its polymerization. Paclitaxel was the first microtubule stabilizing agent used as anticancer drug in chemotherapy...
01:23Microtubule Formation
Microtubules are dynamic structures that undergo continuous assembly and disassembly. They originate from specialized multi-protein complexes known as microtubule organizing centers or MTOCs. Within the MTOC, the point of origin of the microtubule is known as the minus end, while the end radiating outward is the plus end. Microtubules serve two primary functions — the organization of spindle complexes to separate sister chromatids during mitotic or meiotic cell division and the formation of...
02:17Microtubule Instability
Microtubules are hollow cylindrical filaments having a diameter of approximately 25 nm and a length that varies from 200 nm to 25 μm. GTP-bound tubulin subunits form αβ-heterodimers for microtubule assembly. These core building blocks interact longitudinally, polymerizing into protofilaments. The protofilaments then interact with one another through lateral bonding forces to form stable cylindrical microtubules. These cylindrical filaments are dynamic as they undergo repeated assembly and...
02:17Microtubule Instability
Microtubules are hollow cylindrical filaments having a diameter of approximately 25 nm and a length that varies from 200 nm to 25 μm. GTP-bound tubulin subunits form αβ-heterodimers for microtubule assembly. These core building blocks interact longitudinally, polymerizing into protofilaments. The protofilaments then interact with one another through lateral bonding forces to form stable cylindrical microtubules. These cylindrical filaments are dynamic as they undergo repeated assembly and...