Population Analysis of Cell Variability in Autophagic Flux Reveals a Central Inhibitory Role for JNK

Signaling event dynamics in single cells vary within populations and thus differ from commonly-reported metrics, including population-averaged and representative responses.  Cell-cell variability within a population represents an important phenotype for identifying and measuring the response to intrinsic and extrinsic stimuli.  Using the ImageStream System, which combines high-resolution imaging with flow cytometry, and rich feature extraction with statistical analysis, we measured multiple parameters of autophagic flux within cellular populations of MCF-7 cells expressing the autophagy marker GFP-LC3.  With this approach we investigated the early (3h) impact of pathways involved in nutrient deprivation and death receptor apoptotic signaling.  Our results suggest that pro-survival IKK/NFκB and Bcl-2 positively regulate autophagy, and that and JNK is a critical negative regulator of autophagy.