EWSR1 regulates mitosis by dynamically influencing microtubule acetylation
Yi-Long Wang1, Hui Chen1, Yi-Qun Zhan1
1a State Key Laboratory of Proteomics , Beijing Proteome Research Center, Beijing Institute of Radiation Medicine , Beijing , China.
Abstract:
EWSR1, participating in transcription and splicing, has been identified as a translocation partner for various transcription factors, resulting in translocation, which in turn plays crucial roles in tumorigenesis. Recent studies have investigated the role of EWSR1 in mitosis. However, the effect of EWSR1 on mitosis is poorly understood. Here, we observed that depletion of EWSR1 resulted in cell cycle arrest in the mitotic phase, mainly due to an increase in the time from nuclear envelope breakdown to metaphase, resulting in a high percentage of unaligned chromosomes and multipolar spindles. We also demonstrated that EWSR1 is a spindle-associated protein that interacts with α-tubulin during mitosis. EWSR1 depletion increased the cold-sensitivity of spindle microtubules, and decreased the rate of spindle assembly. EWSR1 regulated the level of microtubule acetylation in the mitotic spindle; microtubule acetylation was rescued in EWSR1-depleted mitotic cells following suppression of HDAC6 activity by its specific inhibitor or siRNA treatment. In summary, these results suggest that EWSR1 regulates the acetylation of microtubules in a cell cycle-dependent manner through its dynamic location on spindle MTs, and may be a novel regulator for mitosis progress independent of its translocation.
Insights
EWSR1 protein is crucial for cell division (mitosis). Depleting EWSR1 disrupts chromosome alignment and spindle formation, highlighting its role in cell cycle regulation.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Ewing Sarcoma Breakpoint Region 1 (EWSR1) is involved in transcription and splicing.
- EWSR1 is a known translocation partner in tumorigenesis.
- Its role in mitosis remains largely uncharacterized.
Purpose of the Study:
- To investigate the function of EWSR1 in mitosis.
- To elucidate the molecular mechanisms by which EWSR1 influences cell cycle progression.
Main Methods:
- EWSR1 depletion using siRNA.
- Cell cycle analysis via flow cytometry.
- Immunofluorescence microscopy to assess spindle and chromosome dynamics.
- Co-immunoprecipitation to identify protein interactions.
- Microtubule cold-sensitivity assays.
- Analysis of microtubule acetylation levels.
Main Results:
- EWSR1 depletion causes mitotic cell cycle arrest.
- Increased time from nuclear envelope breakdown to metaphase, unaligned chromosomes, and multipolar spindles observed.
- EWSR1 interacts with α-tubulin and is spindle-associated.
- EWSR1 depletion affects microtubule stability and assembly rate.
- EWSR1 regulates mitotic spindle microtubule acetylation, modulated by HDAC6.
Conclusions:
- EWSR1 is a novel regulator of mitosis, independent of its translocation role.
- EWSR1 dynamically localizes to spindle microtubules to regulate their acetylation.
- These findings provide new insights into cell cycle control and potential therapeutic targets.
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