Abstract
Apoptosis is crucial during the morphogenesis of most organs and tissues, and is utilized for tissues to achieve their proper size, shape and patterning. Many signaling pathways contribute to the precise regulation of apoptosis. Here we show that Jun N-terminal Kinase (JNK) activity contributes to the coordinated removal of interommatidial cells via apoptosis in the Drosophila pupal retina. This is consistent with previous findings that JNK activity promotes apoptosis in other epithelia. However, we found that JNK activity is repressed by Cindr (the CIN85 and CD2AP ortholog) in order to promote cell survival. Reducing the amount of Cindr resulted in ectopic cell death. Increased expression of the Drosophila JNK basket in the setting of reduced cindr expression was found to result in even more severe apoptosis, whilst ectopic death was found to be reduced if retinas were heterozygous for basket. Hence Cindr is required to properly restrict JNK-mediated apoptosis in the pupal eye, resulting in the correct number of interommatidial cells. A lack of precise control over developmental apoptosis can lead to improper tissue morphogenesis.
Highlights
The removal of cells by apoptosis is a fundamental feature of tissue and organ morphogenesis, homeostasis and pathogenesis (Fuchs and Steller, 2011)
Cindr is required for the proper survival of interommatidial cells (ICs) in the Drosophila pupal eye The Drosophila eye is striking in its order
Since 1° cells are recruited from the pool of interommatidial cells from ∼18 through ∼23 h after puparium formation (APF) we included these in our cell counts
Summary
The removal of cells by apoptosis is a fundamental feature of tissue and organ morphogenesis, homeostasis and pathogenesis (Fuchs and Steller, 2011). Death-associated inhibitor of apoptosis 1 (Diap1) is widely expressed in Drosophila tissues and binds directly to apoptotic caspases to inhibit their activity (Hawkins et al, 1999; Hay et al, 1995; Vucic et al, 1997; Vucic et al, 1998). In response to apoptotic stimuli that include developmental and stress signals, the RHG proteins, Reaper (Rpr), Head involution defective (Hid) and Grim bind Diap, promoting its degradation (Bergmann et al, 1998; Chen et al, 1996; Goyal et al, 2000; Grether et al, 1995; Lisi et al, 2000; Ryoo et al, 2002; Wang et al, 1999; White et al, 1994; Wilson et al, 2002). Direct phosphorylation of Hid by the mitogen-activated protein kinase (MAPK) Rolled that is activated downstream of the EGFR inhibits Hid activity to promote cell survival (Bergmann et al, 1998; Bergmann et al, 2002)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
