Lysosomal Machinery Drives Extracellular Acidification to Direct Non-apoptotic Cell Death

Abstract

SUMMARY Cell death is a fundamental aspect of development, homeostasis, and disease; yet, our understanding of non-apoptotic forms of cell death is limited. One such form is phagoptosis, in which one cell utilizes phagocytosis machinery to kill another cell that would otherwise continue living. We have previously identified a non-autonomous requirement of phagocytosis machinery for the developmental programmed cell death of germline nurse cells in the Drosophila ovary; however, the precise mechanism of death remained elusive. Here, we show that lysosomal machinery acting in epithelial follicle cells is used to non-autonomously induce the death of nearby germline cells. Stretch follicle cells recruit V-ATPases and chloride channels to their plasma membrane to extracellularly acidify the germline and release cathepsins that destroy the nurse cells. Our results reveal a role for lysosomal machinery acting at the plasma membrane to cause the death of neighboring cells, providing insight into mechanisms driving non-autonomous cell death.

Investigation of Isoform Specific Functions of the V-ATPase a Subunit During Drosophila Wing Development

“…Previous studies using RNAi knock-down experiments indicate that Vha100-2 is involved in the development of multiple fly tissues (Wang et al, 2014;Overend et al, 2016;Mondragon et al, 2019;Nagata et al, 2019). We find that Vha100-2 is the sole isoform required for wing cuticle integrity.…”

“…Loss of Vha100-1 leads to vesicle accumulation in synaptic terminals (Wang et al, 2014), neuronal degeneration (Williamson et al, 2010a), and defects in brain wiring (Williamson et al, 2010b). RNAi knock-down experiments indicate that Vha100-2 is involved in regulation of neural stem cells proliferation (Wissel et al, 2018), acid generation of the midgut (Overend et al, 2016), elimination of nurse cells in the ovary (Mondragon et al, 2019), and cell competition in the eye disk (Nagata et al, 2019). Similar as Vha100-2, knock-down of Vha100-4 also leads to acidification defect in the larval midgut (Overend et al, 2016).…”

“…Therefore, the C subunit is well positioned to control the reversible dissociation of the V-ATPase complex ( Inoue et al, 2005 ; Forgac, 2007 ). The C subunit is encoded by Vha44 in Drosophila , which is required for endolysosomal acidification and regulates elimination of nurse cells in the ovary ( Mondragon et al, 2019 ), cell competition in the eye imaginal disk ( Nagata et al, 2019 ), and apical endocytosis in the wing disk epithelial cells ( Gleixner et al, 2014 ). Ectopic Vha44 expression is shown to impair endolysosomal degradation and induce invasive cell behavior in the developing wing disk ( Petzoldt et al, 2013 ) as well as differentiation defects in the eye disk ( Portela et al, 2018 ).…”

A single-cell atlas and lineage analysis of the adult Drosophila ovary

“…Instead, this cluster highly expresses Vha16-1 (Fig. 7e), which is expressed in stretch cells starting at Stage 10 to induce nurse cell death 61 . In addition, this cluster also contains a subset of cells that express Sox14, which we found is expressed in late-stage follicles beginning in Stage 9 (Fig.…”

A Single-Cell Atlas and Lineage Analysis of the Adult Drosophila Ovary

“…Cluster 2.0.1 is enriched for Vha16-1 (Fig. S7K,N), which is expressed in stretch cells starting at Stage 10 to induce nurse cell death, 59 and thus contains older stretch cells than Cluster 2.0.0. Cluster 2.1 is highly enriched for cells that express Yp1 (Fig.…”