Live imaging and single-cell analysis reveal differential dynamics of autophagy and apoptosis |
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Authors: | Yangqing Xu Junying Yuan Marta M. Lipinski |
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Affiliation: | 1.Department of Systems Biology; Harvard Medical School; Boston, MA USA;2.Department of Cell Biology; Harvard Medical School; Boston, MA USA;3.Department of Anesthesiology; University of Maryland School of Medicine; Baltimore, MD USA |
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Abstract: | Autophagy is induced by many cytotoxic stimuli but it is often unclear whether, under specific conditions, autophagy plays a prosurvival or a prodeath role. To answer this critical question we developed a novel methodology that employs automated live microscopy and image analysis to measure autophagy and apoptosis simultaneously in single cells. We used this approach to perform a systems-level analysis of pathway dynamics for both autophagy and apoptosis. We found that induction of autophagy in response to different stimuli is uniformly unimodal; in contrast, cells induce apoptosis in an all-or-none bimodal fashion. By tracking the fate of single cells we found that autophagy precedes apoptosis, and that within the same population apoptosis is delayed in cells that mount a stronger autophagy response. Inhibition of autophagy by knocking down ATG5 promoted apoptosis, thus confirming that autophagy plays a protective role. We anticipate that our single-cell approach will be a powerful tool for gaining a quantitative understanding of the complex regulation of autophagy, its influence on cell fate decisions and its relationship with other cellular pathways. |
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Keywords: | autophagy single cell live cell apoptosis crosstalk image analysis cell tracking |
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