UBC13 is an RNF213-associated E2 ubiquitin-conjugating enzyme, and Lysine 63-linked ubiquitination by the RNF213-UBC13 axis is responsible for angiogenic activity.

Moyamoya disease (MMD) is a cryptogenic vascular disorder in the intracranial arteries. RING protein 213 (RNF213) is the susceptibility gene for MMD, and encodes a RING domain and a Walker motif. Herein, we identified UBC13 (UBE2N) as an E2 ubiquitin-conjugating enzyme for RNF213 E3 ubiquitin ligase by yeast two-hybrid screening with a fragment containing RNF213 RING domain as bait, and the immunocomplex of RNF213-UBC13 was detected . Analysis of the ubiquitin chain on RNF213 by monitoring autoubiquitination showed that RNF213 was autoubiquitinated in a K63 chain fashion, but not in a K48 chain fashion. Finally, this RNF213 ubiquitination in a UBC13-dependent manner was required for cell mobility and invasion activity for HUVEC cells in UBC13 knock-down and ubiquitination-dead RNF213 mutant expressing experiments. These findings demonstrated that RNF213 is a K63-linked E3 ubiquitin ligase, and UBC13 is responsible for RNF213 dependent ubiquitination. The RNF213-UBC13 axis may be associated with angiogenic activity and MMD.