Browsing by keyword "Body, Simon C."
Now showing items 1-3 of 3
-
Activation of autophagy during cell death requires the engulfment receptor DraperAutophagy degrades cytoplasmic components that are required for cell survival in response to starvation. Autophagy has also been associated with cell death, but it is unclear how this is distinguished from autophagy during cell survival. Drosophila salivary glands undergo programmed cell death that requires autophagy genes, and engulfment of salivary gland cells by phagocytes does not appear to occur. Here we show that Draper (Drpr), the Drosophila melanogaster orthologue of the Caenorhabditis elegans engulfment receptor CED-1, is required for autophagy during cell death. Null mutations in, and salivary gland-specific knockdown of, drpr inhibit salivary gland degradation. Knockdown of drpr prevents the induction of autophagy in dying salivary glands, and expression of the Atg1 autophagy regulator in drpr mutants suppresses the failure in degradation of salivary glands. Surprisingly, drpr is required in the same dying salivary gland cells in which it regulates autophagy induction, but drpr knockdown does not prevent starvation-induced autophagy in the fat body, which is associated with survival. In addition, components of the conserved engulfment pathway are required for clearance of dying salivary glands. To our knowledge, this is the first example of an engulfment factor that is required for self-clearance of cells. Further, Drpr is the first factor that distinguishes autophagy that is associated with cell death from autophagy associated with cell survival.
-
Cell-nonautonomous function of ceramidase in photoreceptor homeostasisNeutral ceramidase, a key enzyme of sphingolipid metabolism, hydrolyzes ceramide to sphingosine. These sphingolipids are critical structural components of cell membranes and act as second messengers in diverse signal transduction cascades. Here, we have isolated and characterized functional null mutants of Drosophila ceramidase. We show that secreted ceramidase functions in a cell-nonautonomous manner to maintain photoreceptor homeostasis. In the absence of ceramidase, photoreceptors degenerate in a light-dependent manner, are defective in normal endocytic turnover of rhodopsin, and do not respond to light stimulus. Consistent with a cell-nonautonomous function, overexpression of ceramidase in tissues distant from photoreceptors suppresses photoreceptor degeneration in an arrestin mutant and facilitates membrane turnover in a rhodopsin null mutant. Furthermore, our results show that secreted ceramidase is internalized and localizes to endosomes. Our findings establish a role for a secreted sphingolipid enzyme in the regulation of photoreceptor structure and function.
-
Flies kNOw how to signalA recent study has discovered a surprising role for nitric oxide in the Drosophila immune response. NO-mediated signaling was implicated in the communication between the site of a localized infection and the major immune organ of the fly, the fat body.