Anastasis: A Novel Cell Survival Mechanism

Anastasis: A Novel Cell Survival Mechanism Project Summary Anastasis is a newly discovered cell recovery mechanism that rescues apoptotic cells from the brink of death. Challenging the classic view of irreversible apoptosis, we have discovered robust reversibility of apoptosis in three types of mouse/rat primary cells, twelve human cancer cell lines, and egg chambers in fruit flies. What are the physiological functions, pathological roles, and therapeutic potentials of anastasis? Anastasis could be an unexpected cytoprotective mechanism for preserving terminally differentiated cells and tissues that are difficult to replace, such as cardiomyocytes and neurons. If true, enhancing anastasis may be beneficial for treating heart failure and brain injury. Besides, anastasis could be an unrecognized escape tactic enabling cancer cells to survive cancer therapy, thereby contributing to disease recurrence. If confirmed, suppressing anastasis in dying cancer cells may promote cancer cell death and reduce the chances of recurrence. Anastasis may also play important roles in limiting apoptosis during embryonic development and normal homeostasis. If identified, understanding its regulation can provide new insights into the control of cell death and survival in physiological conditions. However, there are several challenges of testing these hypotheses. It is difficult to track anastasis, especially in vivo, because cells that have reversed apoptosis are morphologically indistinguishable from healthy cells. There are no anastasis-specific hallmarks identified, and the regulators of anastasis remain undiscovered. Here, we will overcome many of these challenges by developing a novel and highly specific tracking system to label anastatic cells for mammalian studies, and to identify the key regulators of anastasis. To mark anastatic cells, we will create an anastasis biosensor that can tag anastatic cells with permanent expression of a fluorescent protein only after they have recovered from both mitochondrial outer membrane permeabilization (MOMP) and caspase-3 activation, the two most recognized apoptotic events, making this biosensor system highly specific to anastasis. We will establish anastasis biosensor stable cell lines to determine reversibility of apoptosis in vitro, and will employ biosensor xenografts to interrogate anastasis in vivo using clinically relevant mouse models. To elucidate the mechanism of anastasis, we will identify its key regulators, through proteomics, genetics, and pharmacological approaches. We will identify which genes exhibit up- or down-expression (potential anastasis regulators, and therapeutic targets) during different stages of anastasis, determine whether specific post-translational modifications distinguish anastatic cells, establish whether cells that recover from different cell death inductions share similar molecular features, and investigate how interfering with anastasis regulator candidates could modulate the reversibility of apoptosis. We will identify small molecules that target the candidates by bioinformatics, and test their efficacy in promoting or suppressing anastasis in vitro. Successful completion of this project will generate essential tools and knowledge for studying anastasis, thereby laying a strong foundation for developing revolutionary new therapeutic approaches by controlling anastasis.