A screen for deubiquitinating enzymes involved in the Gâ‚‚/M checkpoint identifies USP50 as a regulator of HSP90-dependent Wee1 stability.

Tight regulation of cell cycle progression is essential for the maintenance of genomic integrity in response to DNA injury. The aim of this study was to identify new deubiquitinating enzymes (DUBs) involved in the regulation of the Gâ‚‚/M checkpoint. By using an siRNA-based screen to identify DUBs with an inherent ...
ability to enhance a CDC25B-dependent Gâ‚‚/M checkpoint bypass, we have identified 11 candidates whose invalidation compromises checkpoint stringency. We subsequently focused our attention on one of these, the previously uncharacterized USP50. Using a TAP-tag approach associated to mass spectrometry, in addition to a yeast-two-hybrid screen, we identified HSP90 as a major interacting partner for USP50. We also demonstrate USP50 depletion causes a loss in accumulation of the HSP90 client Wee1, which is an essential component of the Gâ‚‚/M cell cycle arrest. Finally, we show that in response to DNA damaging agents, USP50 accumulates in the nucleus. We propose that USP50 may act through a HSP90-dependent mechanism to counteract CDC25B mitotic inducing activity and prevent Wee1 degradation, thereby repressing entry into mitosis following activation of the DNA damage checkpoint.
Mesh Terms:
Cell Cycle Proteins, Cell Division, Cell Line, Cell Nucleus, DNA Damage, Endopeptidases, G2 Phase, HSP90 Heat-Shock Proteins, Humans, Mass Spectrometry, Nuclear Proteins, Protein Stability, Protein-Tyrosine Kinases, RNA Interference, RNA, Small Interfering, Two-Hybrid System Techniques, cdc25 Phosphatases
Cell Cycle
Date: Sep. 15, 2010
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