American Association for Cancer Research
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Supplementary Video 3 from Deubiquitination of γ-Tubulin by BAP1 Prevents Chromosome Instability in Breast Cancer Cells

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posted on 2023-03-30, 22:44 authored by Reihaneh Zarrizi, Julien Albert Menard, Mattias Belting, Ramin Massoumi

Live cell microscopy of MDA-MB-468 inducibly expressing empty expression plasmid and transiently transfected with H2B-GFP. The movie shows anaphase bridge.



Microtubule nucleation requires the γ-tubulin ring complex, and during the M-phase (mitosis) this complex accumulates at the centrosome to support mitotic spindle formation. The posttranslational modification of γ-tubulin through ubiquitination is vital for regulating microtubule nucleation and centrosome duplication. Blocking the BRCA1/BARD1-dependent ubiquitination of γ-tubulin causes centrosome amplification. In the current study, we identified BRCA1-associated protein-1 (BAP1) as a deubiquitination enzyme for γ-tubulin. BAP1 was downregulated in metastatic adenocarcinoma breast cell lines compared with noncancerous human breast epithelial cells. Furthermore, low expression of BAP1 was associated with reduced overall survival of patients with breast cancer. Reduced expression of BAP1 in breast cancer cell lines was associated with mitotic abnormalities. Importantly, rescue experiments including expression of full length but not the catalytic mutant of BAP1 reduced ubiquitination of γ-tubulin and prevented mitotic defects. Our study uncovers a new mechanism for BAP1 involved in deubiquitination of γ-tubulin, which is required to prevent abnormal mitotic spindle formation and genome instability. Cancer Res; 74(22); 6499–508. ©2014 AACR.