Fernández-Marrero Yuniel, Bleicken Stephanie, Das Kushal Kumar, Bachmann Daniel, Kaufmann Thomas, Garcia-Saez Ana J
Institute of Pharmacology, University of Bern, Switzerland.
Interfaculty Institute of Biochemistry, University of Tübingen, Germany.
FEBS J. 2017 Mar;284(5):711-724. doi: 10.1111/febs.14008. Epub 2017 Feb 1.
The BCL-2 family members are key regulators of the intrinsic apoptotic pathway, which is defined by permeabilization of the mitochondrial outer membrane by members of the BAX-like subfamily. BOK is classified as a BAX-like protein; however, its (patho-)physiological role remains largely unclear. We therefore assessed the membrane permeabilization potential of C-terminally truncated recombinant BOK, BOK . We show that BOK can permeabilize liposomes mimicking the composition of mitochondrial outer membrane, but not of endoplasmic reticulum, forming large and stable pores over time. Importantly, pore formation was enhanced by the presence of cBID and refractory to the addition of antiapoptotic BCL-X . However, isolated mitochondria from Bax Bak cells were resistant to BOK-induced cytochrome c release, even in the presence of cBID. Taken together, we show that BOK can permeabilize liposomes, and cooperate with cBID, but its role in directly mediating mitochondrial permeabilization is unclear and may underlie a yet to be determined negative regulation.
BCL-2家族成员是内源性凋亡途径的关键调节因子，该途径由BAX样亚家族成员使线粒体外膜通透化来定义。BOK被归类为BAX样蛋白；然而，其（病理）生理作用在很大程度上仍不清楚。因此，我们评估了C端截短的重组BOK（BOK ）的膜通透化潜力。我们发现BOK能够使模拟线粒体外膜组成的脂质体通透化，但不能使内质网脂质体通透化，并且随着时间的推移会形成大而稳定的孔。重要的是，cBID的存在会增强孔的形成，而添加抗凋亡蛋白BCL-X 则对其有抗性。然而，即使存在cBID，来自Bax Bak双敲除细胞的分离线粒体对BOK诱导的细胞色素c释放具有抗性。综上所述，我们表明BOK能够使脂质体通透化，并与cBID协同作用，但其在直接介导线粒体通透化中的作用尚不清楚，可能构成一种有待确定的负调控机制。
