Steroid regulation of autophagic programmed cell death during development.
Apoptosis and autophagy are morphologically distinct forms of programmed cell death. While autophagy occurs during the development of diverse organisms and has been implicated in tumorigenesis, little is known about the molecular mechanisms that regulate this type of cell death. Here we show that steroid-activated programmed cell death of Drosophila salivary glands occurs by autophagy. Expression of p35 prevents DNA fragmentation and partially inhibits changes in the cytosol and plasma membranes of dying salivary glands, suggesting that caspases are involved in autophagy. The steroid-regulated BR-C, E74A and E93 genes are required for salivary gland cell death. BR-C and E74A mutant salivary glands exhibit vacuole and plasma membrane breakdown, but E93 mutant salivary glands fail to exhibit these changes, indicating that E93 regulates early autophagic events. Expression of E93 in embryos is sufficient to induce cell death with many characteristics of apoptosis, but requires the H99 genetic interval that contains the rpr, hid and grim proapoptotic genes to induce nuclear changes diagnostic of apoptosis. In contrast, E93 expression is sufficient to induce the removal of cells by phagocytes in the absence of the H99 genes. These studies indicate that apoptosis and autophagy utilize some common regulatory mechanisms.
Center for Agricultural Biotechnology, University of Maryland Biotechnology Institute, College Park, Maryland 20742, USA.
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Lee
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Baehrecke
D000818:Animals; D017209:Apoptosis; D001343:Autophagy; D018955:CD36 Antigens / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D004330:Drosophila / Q000196:embryology; D029721:Drosophila Proteins; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D009479:Neuropeptides / Q000235:genetics; D010455:Peptides / Q000235:genetics; D011971:Receptors, Immunologic / Q000235:genetics; D051116:Receptors, Scavenger; D012469:Salivary Glands / Q000166:cytology*; D013256:Steroids / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014764:Viral Proteins / Q000235:genetics
C102117:Br protein, Drosophila; D018955:CD36 Antigens; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C060408:Eip74EF protein, Drosophila; C095837:Eip93F protein, Drosophila; C108880:HID protein, Drosophila; D009479:Neuropeptides; D010455:Peptides; D011971:Receptors, Immunologic; D051116:Receptors, Scavenger; D013256:Steroids; D014157:Transcription Factors; D014764:Viral Proteins; C099526:crq protein, Drosophila; C108881:grim protein, Drosophila; C081618:p35 protein, Nucleopolyhedrovirus; C086973:rpr protein, Drosophila