BioID based proteomic analysis of the Bid interactome identifies novel proteins involved in cell cycle dependent apoptotic priming.

Apoptotic priming controls the commitment of cells to apoptosis by determining how close they lie to mitochondrial permeabilisation. Variations in priming are important for how both healthy and cancer cells respond to chemotherapeutic agents, but how this is dynamically coordinated by Bcl-2 proteins remains unclear. The Bcl-2 family protein Bid is phosphorylated when cells enter mitosis, increasing apoptotic priming and sensitivity to anti-mitotic drugs. Here we report an unbiased proximity biotinylation (BioID) screen to identify regulators of apoptotic priming in mitosis, using Bid as bait. The screen primarily identified proteins outside of the canonical Bid interactome. Specifically, we found that voltage-dependent anion-selective channel protein 2 (VDAC2) was required for Bid phosphorylation dependent changes in apoptotic priming during mitosis. Thus, we identify an additional layer of regulation upstream of known Bid interactions that control dynamic changes in apoptotic priming. These results highlight the importance of understanding the wider Bcl-2 family interactome and its role in regulating the temporal control of apoptotic priming.