CasExpress reveals widespread and diverse patterns of cell survival of caspase-3 activation during development in vivo

Abstract

Caspase-3 carries out the executioner phase of apoptosis, however under special circumstances, cells can survive its activity. To document systematically where and when cells survive caspase-3 activation in vivo, we designed a system, CasExpress, which drives fluorescent protein expression, transiently or permanently, in cells that survive caspase-3 activation in Drosophila. We discovered widespread survival of caspase-3 activity. Distinct spatial and temporal patterns emerged in different tissues. Some cells activated caspase-3 during their normal development in every cell and in every animal without evidence of apoptosis. In other tissues, such as the brain, expression was sporadic both temporally and spatially and overlapped with periods of apoptosis. In adults, reporter expression was evident in a large fraction of cells in most tissues of every animal; however the precise patterns varied. Inhibition of caspase activity in wing discs reduced wing size demonstrating functional significance. The implications of these patterns are discussed.DOI: http://dx.doi.org/10.7554/eLife.10936.001

The impact of non-genetic heterogeneity on cancer cell death

“…However, in primary mouse liver and NIH 3T3 cells, over 90% of cells treated with lethal doses of ethanol can reverse canonical apoptotic hallmarks (including caspase activation, nuclear condensation, and mitochondrial fragmentation) if ethanol is removed from cells after 5 hours (Tang et al 2012). This reversal of apoptosis, referred to as anastasis, has also been observed in vivo throughout the development and lifespan of Drosophila (Tang et al 2015; Ding et al 2016) (Figure 3D). Reversal of apoptosis after application of lethal ethanol doses was associated with increased expression of heat shock proteins and antiapoptotic BCL2 family members, and small molecule inhibitors of BCL2, XIAP, MDM2, and HSP90 dramatically reduced the frequency of anastasis (from 90% of cells to around 40%) (Tang et al 2012).…”

Stress-Induced Mutagenesis: Implications in Cancer and Drug Resistance

“…Recovered NIH 3T3 cells also displayed hallmarks of oncogenic transformation, such as anchorage-independent growth and loss of contact inhibition. Recovery from late-stage apoptosis occurs frequently in flies (Ding et al 2016) and is likely to occur in other organisms. Therefore, transient stress can trigger incomplete apoptosis and recovery, resulting in transient genome instability and potentially initiating tumorigenesis.…”

Detecting Anastasis <em>In Vivo</em> by CaspaseTracker Biosensor

“…While caspase activity has been traditionally assumed as a hallmark of apoptosis, growing studies reveal that non-apoptotic caspase activity plays potential roles in diverse normal cell functions, such as regulation of neuronal activity 79,80 , learning and memory 81,82,83,84 , suppression of necroptotic cell death 85,86 , spermatid individualization 87,88 , microRNA processing 89 , cell proliferation 90 , and cell fate patterning 91 . In addition to apoptosis and anastasis, the CaspaseTracker biosensor system can therefore detect non-apoptotic caspase activity, which is present in the brain and optic lobes, cardia, gut, Malpighian tubules, trachea, muscles, and other tissues of Drosophila 19,46,64 . This biosensor signal could also represent the current or past anastatic activity during embryo development or normal homeostasis in these tissues.…”

“…However, it is technically challenging to identify and track anastatic cells in vivo , because the cells that recovered from cell death process appear morphologically indistinguishable from normal healthy cells, and there is no biomarker of anastasis identified yet 17,18,21 . To address these problems, we recently developed a new in vivo caspase biosensor designated “CaspaseTracker” 19 , to identify and track cells that survive apoptosis after caspase activation 19,46 , the hallmark of apoptosis 10,14 . Distinguishing it from the “real-time” caspase biosensors such as SCAT 12,47 , Apoliner 48 , CA-GFP 49 , ApoAlert 18,50 , C3AIs 51 and iCasper 52 that detect on-going caspase activity, the CaspaseTracker biosensor additionally features the ability to permanently label cells that express caspase activity even transiently.…”