Ring- and arc-shaped pores drive stressed cells to a programmed death
Damaged cells can commit suicide by a process of apoptosis, or programmed cell death. If this mechanism fails to work properly, the cell can become cancerous. Scientists are helping to explain important steps in the process of apoptosis. They know from previous studies that apoptosis begins with the activation of what are known as Bax proteins. If a cell is under stress, Bax proteins deposit on the surface of mitochondria in symmetrical pairs. The researchers then observed that the otherwise impermeable shell of the mitochondria becomes permeable – letting through cytochrome c. Once that happens, the process of cellular death cannot be reversed. But what happened in between was a mystery which for a long time puzzled apoptosis researchers. Now Ana García-Sáez and her team have been able to use a supermicroscope to watch how Bax proteins form pores in the mitochondrial shell, making it permeable.