Cellular Stress Switch Governs Survival or Death
BGU researchers uncovered a redox-sensitive molecular switch that determines whether stressed cells survive or undergo programmed death.
A new study from Ben-Gurion University of the Negev (BGU) has identified a pivotal molecular switch that controls whether stressed human cells activate an adaptive survival mechanism or trigger programmed cell death (apoptosis). The findings, published in Redox Biology, provide crucial mechanistic insights that could help overcome chemotherapy resistance in aggressive tumors.
The study was led by Dr. Aeid Igbaria alongside co-lead authors Laila Abu Madegam and Noa Gavriel, and researcher Raifu Tolulope Adebisi, all from BGU’s Department of Life Sciences.
The Cellular Emergency Escape Hatch
The endoplasmic reticulum (ER) serves as the cell’s primary protein production and folding center. When subjected to physiological stress, the ER relieves internal pressure through an adaptive process known as ER-to-Cytosol Signaling (ERCYS). Through this pathway, select proteins escape the ER into the surrounding cytosol, where they acquire protective functions that block tumor suppressors and deactivate cell-death enzymes such as caspase-3 and wt-p53.
While cancer cells frequently hijack this pathway to survive harsh microenvironments and resist drug treatments, the molecular mechanism governing when this escape route operates—and why it shuts down under extreme stress—has long remained unclear.
A Redox-Driven Tipping Point
Using pharmacological and physiological stress models across multiple human cell lines, the BGU research team discovered that this survival mechanism operates within a tightly defined stress window controlled by the cell's chemical reduction-oxidation (redox) balance:
• Mild Stress Activates Survival: Under the moderate stress typical of physiological and pathophysiological conditions, the ER cochaperones DNAJB12 and DNAJB14 remain structurally intact, held in their functional conformation by intramolecular disulfide bonds. This stability allows them to carry out a dual protective role: relocating ER-resident proteins to the cytosol for handoff to SGTA, while simultaneously targeting pro-apoptotic proteins for proteasomal degradation — actively suppressing the cell death program before it can be engaged.
• Severe Stress Triggers Degradation: When cellular stress becomes overwhelming, elevated levels of intracellular antioxidant glutathione break these chemical bonds. Without this structural stabilization, DNAJB12 and DNAJB14 are rapidly targeted for degradation and destroyed.
• Puncturing the Membrane for Cell Death: This dual collapse, loss of chaperone-mediated protein relocation and failure of proteasomal control over pro-apoptotic proteins, allows BIK to accumulate unchecked. BIK, an ER-resident death-promoting protein, in turn recruits BAX and BAK, pore-forming executioner proteins of the BCL-2 family, to the ER membrane, where they oligomerize and permeabilize it, committing the cell irreversibly to apoptosis, targeting Chemoresistance and Ischemic Injury.
"Our findings demonstrate that the cell's internal redox balance functions as a definitive molecular scale," explains Dr. Aeid Igbaria. "Instead of a passive structural breakdown, the cell actively measures stress levels through the integrity of these chemical bonds. Under manageable stress, it deploys molecular chaperones to survive, but when the stress threshold is breached, it systematically dismantles those protectors to execute cell death."
"Understanding how this switch is flipped gives us a clear therapeutic target," adds co-lead author Laila Abu Madegam. "Because cancer cells rely heavily on this chaperone-assisted pathway to resist chemotherapy, disrupting DNAJB12 and DNAJB14 or altering the ER redox environment could strip tumor cells of their defenses and force them into apoptosis."
The researchers also verified this molecular cascade in cardiac models of hypoxia-reoxygenation, indicating that modulating this switch could similarly offer new strategies to protect heart muscle from massive cell death following ischemic injury.
This work was supported by the Israel Science Foundation (ISF) (Grant No. 977/21) and the Israel Cancer Research Fund (ICRF) Research Career Development Award (RCDA). Laila Abu Madegam was supported by a Kreitman School of Advanced Graduate Studies STEM Fellowship and the Ariane de Rothschild Fellowship, and Raifu Adebisi was supported by the Kreitman School of Advanced Graduate Studies.
