The Crosstalk Between CRL5 and APC/C E3 Ligases Regulates Metastasis and Chemosensitivity of Cancer Cells.

Cullin-RING ligases (CRLs) and the anaphase-promoting complex/cyclosome (APC/C) are two major multi-subunit ubiquitin ligases essential for protein homeostasis. The underlying mechanism and biological consequence of their crosstalk remain elusive. Here, tandem affinity purification followed by LC-MS/MS is employed, and identified APC11-the RING subunit of APC/C-as a bona fide binding partner of CUL5, the scaffold of CRL5. On one hand, APC11 interacts with CUL5 and inhibits its neddylation. Consequently, APC11 knockdown enhances CUL5 neddylation by promoting its interaction with the neddylation E2 UBE2F. This leads to the degradation of SOCS3, a substrate receptor of CRL5, and the subsequent accumulation of its substrate, integrin β1, ultimately promoting cancer metastasis. On the other hand, CUL5-APC11 binding stabilizes APC11 by facilitating its atypical K27/K29/K33-linked polyubiquitylation at Lys83, a process catalyzed by ITCH E3 ligase. CUL5 loss delays mitotic exit, induces aneuploidy, and sensitizes cancer cells to the microtubule-targeting drug paclitaxel by destabilizing APC11. Collectively, the study revealed a new crosstalk between CUL5 and APC11 of two major E3 ligases, and targeting this crosstalk can provide a new strategy for blocking metastasis and triggering chemosensitization.