Fig. 1: TOP2β is a novel substrate of CRL E3 ligases. | Oncogenesis

Fig. 1: TOP2β is a novel substrate of CRL E3 ligases.

From: SCFβ-TrCP-mediated degradation of TOP2β promotes cancer cell survival in response to chemotherapeutic drugs targeting topoisomerase II

Fig. 1

a MLN4924 treatment blocks VM-26-induced TOP2β degradation. Cells were left untreated or treated with VM-26 (100 μM) or in combination with MLN4924 (1 μM) for 2 h. Cells were then harvested, and immunoblotting (IB) was undertaken using the indicated antibodies (Abs). b MLN4924 increases TOP2β levels in a dose-dependent manner. Cells were treated with various concentrations of MLN4924 for 24 h, and then, IB was undertaken with the indicated Abs. c MLN4924 treatment extends the protein half-life of TOP2β upon VM-26 treatment. Cells were treated with CHX (100 μg/ml) and VM-26 (100 μM) or in combination with MLN4924 (1 μM) for the indicated time periods, and then, IB was undertaken with the indicated Abs (top). Densitometry quantification was performed with ImageJ, and the decay curves are shown (bottom). d MLN4924 treatment suppresses the polyubiquitination of TOP2β induced by VM-26 treatment. HEK293 cells transfected with the indicated plasmids were treated with VM-26 (100 μM) and MG132 (20 μM) or in combination with MLN4924 (1 μM) for 5 h, and then, IP was conducted with anti-HA beads (top), and direct IB was undertaken with the indicated Abs (bottom). WCE: whole-cell extract. e RBX1 binds to endogenous TOP2β. HEK293 cells transfected with the indicated plasmids were harvested for IP with anti-FLAG beads (top) and direct IB with the indicated Abs (bottom).

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