Non-apoptotic function of Drosophila caspase activation in epithelial thorax closure and wound healing

Abstract

Non-apoptotic caspase activation involves multiple cellular events. However, the link between visible non-apoptotic caspase activation and its function in living organisms has not yet been revealed. Here, we visualized sub-lethal activation of apoptotic signaling with the combination of a sensitive indicator for caspase 3 activation and in vivo live-imaging analysis of Drosophila. During thorax closure in pupal development, caspase 3 activation was specifically observed at the leading edge cells, with no signs of apoptosis. Inhibition of caspase activation led to an increase in thorax closing speed, which suggests a role of non-apoptotic caspase activity in cell motility. Importantly, sub-lethal activation of caspase 3 was also observed during wound closure at the fusion sites at which thorax closure had previously taken place. Further genetic analysis revealed that the activation of the initiator caspase Dronc is coupled with the generation of reactive oxygen species. The activation of Dronc also regulates myosin levels and delays wound healing. Our findings suggest a possible function for non-apoptotic caspase activation in the fine-tuning of cell migratory behavior during epithelial closure.

Failed Apoptosis Enhances Melanoma Cancer Cell Aggressiveness

“…This indicates that the enhanced aggressiveness triggered by failed apoptosis is insensitive to pan-caspase inhibition. Given the recently described involvement of non-apoptotic initiator caspase-9 activity in Drosophila melanogaster epithelial cell migration, we tested the role of active caspase-9 in failed apoptosisdriven melanoma migration (Rudrapatna et al, 2013;Fujisawa et al, 2019;Gorelick-Ashkenazi et al, 2018). This was conducted using the active caspase-9 inhibitor Z-LEHD-FMK.…”

Activatable Photosensitizer for Targeted Ablation of lacZ-Positive Cells with Single-Cell Resolution

“…After VC3Ai signal appearance, the nuclei of lacZ -expressing cells started to fragment, followed by delamination of the cells into the body cavity. As we performed imaging at the side of the midline of the pupal notum (Figure 4a), where sublethal caspase activity is known to be activated, 19 cells closer to the midline are likely to be more sensitive to additional apoptotic stimuli, which may explain why lacZ -positive cells tended to die differently. Further, in the absence of SPiDER-killer-βGal injection and/or light irradiation, only a few VC3Ai signals or nuclear fragmentations were observed (Figure 4b, lower; cells undergoing spontaneous apoptosis can be seen in the time-lapse images with a 1 h time interval in Figure S12b–d).…”

Non-apoptotic function of caspase-3 in morphogenesis of epithelial tubes ofDrosophilarenal system

“…SCs are mesodermal in origin and they undergo mesenchymal to epithelial transition [17] The star shape of SCs, which is a characteristic feature of adults responsible for maximising the surface area of SCs for function, is observed at the larval stage itself in Drice mutants suggesting that caspases has a role in restraining the shape of the SCs, similar to the negative regulation of speed of thorax closure [11]. Teashirt, specifically expresses in the SCs, is required for cell shape changes as well as physiological maturation [18], however, since there is no change in teashirt expression in Drice mutants compared to wild type (Data not shown), it is likely that Drice is acting down stream of Teashirt.…”

“…In tune with this knowledge, several studies in Drosophila support caspase dependent signaling in non-apoptotic processes such as, cytoskeletal remodeling and associated cellular shaping to promote major morphological changes in some sensory neurons during dendritic pruning [8,9], cytoplasmic extrusion during spermatid terminal differentiation, thorax closure in pupal development and trachea elongation by regulating endocytic trafficking of cell polarity and cell junction proteins [10][11][12]. Other than Drosophila, caspase-3 associated non-apoptotic functions have been reported in mammalian red blood cells nuclear extrusion [13], neural development [9], liver regeneration process and skin wound healing [14], showing the conservation of the nonapoptotic role in mammals.…”