title: Live imaging and single-cell analysis reveal differential dynamics of autophagy and apoptosis.
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.
authors.affiliation: Department of Systems Biology; Harvard Medical School; Boston, MA USA.
authors.forename: Yangqing
authors.initials: Y
authors.lastname: Xu
authors.forename: Junying
authors.initials: J
authors.lastname: Yuan
authors.forename: Marta M
authors.initials: MM
authors.lastname: Lipinski
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D021621:Imaging, Three-Dimensional; D007700:Kinetics; D051379:Mice; D059010:Single-Cell Analysis / Q000379:methods*; D020123:Sirolimus / Q000494:pharmacology; D019311:Staurosporine / Q000494:pharmacology; D059008:Time-Lapse Imaging
chemical_list: D019311:Staurosporine; D020123:Sirolimus
keywords: apoptosis; autophagy; cell tracking; crosstalk; image analysis; live cell; single cell