Defining the function of spatiotemporal JNK activation in cell fate determination

Cells must integrate stress information to determine the appropriate response, whether arrest, repair, or death. Not surprisingly, aberrant cell fate is associated with many human pathologies, including inflammatory disease and cancer. As a result, cellular regulators in these pathways have been attractive targets for therapeutic intervention. Despite extensive study of cellular stress responses we still have limited knowledge of how single cells integrate stress information over time to determine their fate. Improvements in live cell imaging have provided insight into this question, as p53, NF-kB, and the stress-activated kinase JNK exhibit temporal expression or activation patterns that correlate with cell fate outcomes and stress-induced gene expression patterns. However, the role of JNK in cell fate remains complex as not only do activation patterns vary but spatial localization is also critical for its function. Recruitment of JNK to the mitochondrial membrane via the scaffold protein Sab is required for sustained activation of JNK associated with induction of cell death and ROS generation. However, it is poorly understood how dynamic recruitment of JNK promotes cell death and the mechanistic trigger at the single cell level. Furthermore, many of the same signaling cascades are engaged in alternative survival mechanisms such as senescence. In preliminary studies, we’ve observed oscillations of JNK activity in cells undergoing therapy-induced senescence suggesting a mechanism of dampening JNK activation over time. Prior modeling studies suggest that feedback via the phosphatase DUSP1 is a potential inducer of these oscillations. We hypothesize that retention time of JNK at mitochondria is critical for the induction of cell death via mitochondrial disruption, while the removal of JNK via DUSP1 can restore cells to homeostasis or maintain senescence depending on the continuation of stress stimuli. Using optogenetic sensors to manipulate JNK localization over time, we will test how the duration of JNK retention at mitochondria influences mitochondrial function, ROS production, and cell death. In our second aim, we will determine mechanisms that limit JNK mediated cell death during the onset of senescence by exploring the role of DUSP1 on JNK pulses and using CRISPR screens to identify key regulators of JNK mediated cell fates. These studies will determine how JNK dictates the determination of cell death, survival, or senescence and inform potential approaches to modulate cell fates. Project Number: 5P20GM135008-05 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of General Medical Sciences (NIGMS) | Principal Investigator: Ryan Hanson | Institution: SOUTH DAKOTA STATE UNIVERSITY, BROOKINGS, SD | Award Amount: $273,651 | Activity Code: P20 | Study Section: ZGM1-RCB-W(C1) View on NIH RePORTER: https://reporter.nih.gov/project-details/11520812