Quantitative assessment of cell fate decision between autophagy and apoptosis

• Published in: Scientific reports Vol. 7; no. 1; pp. 17605 - 14
• Main Authors: Liu, Bing, Oltvai, Zoltán N., Bayır, Hülya, Silverman, Gary A., Pak, Stephen C., Perlmutter, David H., Bahar, Ivet
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 14.12.2017; Nature Publishing Group
• Subjects: 631/114/2391; 631/553/2393; 631/553/2700; 631/80/39; AMP; AMP-activated protein kinase; AMP-Activated Protein Kinases - metabolism; Apoptosis; Apoptosis - physiology; Autophagy; Autophagy - physiology; Calcium; Calcium - metabolism; Calcium-binding protein; Calcium-Calmodulin-Dependent Protein Kinase Kinase - metabolism; Calmodulin; Cell death; Cell fate; Cell Survival; Computer applications; Computer Simulation; Cytoplasm - physiology; Endoplasmic Reticulum Stress; Humanities and Social Sciences; Humans; Kinases; Mortality; multidisciplinary; Phagocytosis; Phosphorylation; Science; Science (multidisciplinary); Signal Transduction; Stress, Physiological - physiology
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-18001-w

Autophagy and apoptosis are cellular processes that regulate cell survival and death, the former by eliminating dysfunctional components in the cell, the latter by programmed cell death. Stress signals can induce either process, and it is unclear how cells ‘assess’ cellular damage and make a ‘life’ or ‘death’ decision upon activating autophagy or apoptosis. A computational model of coupled apoptosis and autophagy is built here to analyze the underlying signaling and regulatory network dynamics. The model explains the experimentally observed differential deployment of autophagy and apoptosis in response to various stress signals. Autophagic response dominates at low-to-moderate stress; whereas the response shifts from autophagy (graded activation) to apoptosis (switch-like activation) with increasing stress intensity. The model reveals that cytoplasmic Ca 2+ acts as a rheostat that fine-tunes autophagic and apoptotic responses. A G-protein signaling-mediated feedback loop maintains cytoplasmic Ca 2+ level, which in turn governs autophagic response through an AMP-activated protein kinase (AMPK)-mediated feedforward loop. Ca 2+ /calmodulin-dependent kinase kinase β (CaMKKβ) emerges as a determinant of the competing roles of cytoplasmic Ca 2+ in autophagy regulation. The study demonstrates that the proposed model can be advantageously used for interrogating cell regulation events and developing pharmacological strategies for modulating cell decisions.