The appearance of cytoplasmic cytochrome C precedes apoptosis during Drosophila salivary gland degradation

• Published in: Insect science Vol. 31; no. 1; pp. 157 - 172
• Main Authors: Long, Shihui, Cao, Wenxin, Qiu, Yongyu, Deng, Ruohan, Liu, Jiali, Zhang, Lidan, Dong, Renke, Liu, Fengxin, Li, Sheng, Zhao, Haigang, Li, Na, Li, Kang
• Format: Journal Article
• Language: English
• Published: Australia Wiley Subscription Services, Inc 01.02.2024
• Subjects: active caspase 3; Animals; Apoptosis; C protein; Caspase 3; Caspases - genetics; Coding; Cytochrome; Cytochrome c; Cytochromes; Cytochromes c - genetics; Cytochromes c - metabolism; Cytoplasm; Cytoplasm - metabolism; Cyt‐c; Degradation; Drosophila; Drosophila - genetics; Drosophila melanogaster - genetics; Exocrine glands; Fruit flies; Genes; Homeostasis; Insects; Mammals; Mammals - metabolism; Membrane potential; Membranes; Mitochondria; Morphogenesis; Photodegradation; Proteins; Salivary gland; Salivary glands; Salivary Glands - metabolism; Transcription factors; salivary gland; active caspase 3; apoptosis; Cyt-c; Drosophila
• DOI: 10.1111/1744-7917.13240
• ISSN: 1672-9609

Apoptosis is an important process for organism development that functions to eliminate cell damage, maintain homeostasis, and remove obsolete tissues during morphogenesis. In mammals, apoptosis is accompanied by the release of cytochrome C (Cyt‐c) from mitochondria to the cytoplasm. However, whether this process is conserved in the fruit fly, Drosophila melanogaster, remains controversial. In this study, we discovered that during the degradation of Drosophila salivary gland, the transcription of mitochondria apoptosis factors (MAPFs), Cyt‐c, and death‐associated APAF1‐related killer (Dark) encoding genes are all upregulated antecedent to initiator and effector caspases encoding genes. The proteins Cyt‐c and the active caspase 3 appear gradually in the cytoplasm during salivary gland degradation. Meanwhile, the Cyt‐c protein colocates with mito‐GFP, the marker indicating cytoplasmic mitochondria, and the change in mitochondrial membrane potential coincides with the appearance of Cyt‐c in the cytoplasm. Moreover, impeding or promoting 20E‐induced transcription factor E93 suppresses or enhances the staining of Cyt‐c and the active caspase 3 in the cytoplasm of salivary gland, and accordingly decreases or increases the mitochondrial membrane potential, respectively. Our research provides evidence that cytoplasmic Cyt‐c appears before apoptosis during Drosophila salivary gland degradation, shedding light on partial conserved mechanism in apoptosis between insects and mammals. During 20‐hydroxyecdysone (20E)‐induced metamorphosis, the transcription of mitochondria apoptosis factors encoding genes (MAPFs), Cyt‐c‐d, and death‐associated APAF1‐related killer encoding gene (Dark) encoding genes are all upregulated antecedent to initiator and effector caspases encoding genes in the Drosophila salivary gland. Cyt‐c protein and the active caspase 3 appear gradually in the cytoplasm, and Cyt‐c colocates with mito‐GFP, a marker indicating cytoplasmic mitochondria. In addition, the change in mitochondrial membrane potential coincides with the appearance of cytoplasmic Cyt‐c during salivary gland degradation. Moreover, impeding or promoting 20E‐induced transcription factor E93 suppresses or enhances the accumulation of Cyt‐c and the active caspase 3 in the cytoplasm of salivary gland, and accordingly decreases or increases the mitochondrial membrane potential, respectively. The research provides evidence that cytoplasmic Cyt‐c appears before apoptosis during Drosophila salivary gland degradation, shedding light on the partial conserved mechanism in apoptosis between insects and mammals.