Autophagy plays an important role in tissue remodeling during insect development.The interplay between autophagy-related(ATG)proteins and caspases regulates the autophagic activity of ATGs,thereby modulating the proce...Autophagy plays an important role in tissue remodeling during insect development.The interplay between autophagy-related(ATG)proteins and caspases regulates the autophagic activity of ATGs,thereby modulating the process of autophagy.Our previous study characterized BmCaspase-8-like(BmCasp8L)as a caspase suppressor that inhibits apoptosis and immune signaling by suppressing the activation of death-related ced-3/Nedd2-like caspase(DREDD),a caspase-8 homolog in silkworm.In this study,we explored the regulatory role of BmCasp8L in autophagy.We found that the expression of Bmcasp8l increased from the late spinning stage to the pupa stage in the posterior silk gland(PSG),correlating with the expression patterns of Bmatg8 and Bmatg6.RNA interference-mediated downregulation of BmCasp8L expression significantly decreased starvation-induced autophagic influx as determined by the levels of BmATG8–phosphatidylethanolamine and the percentage of cells displaying punctate enhanced green fluorescent protein-BmATG8.Conversely,the overexpression of BmCasp8L significantly increased autophagic influx.We also found that BmCasp8L underwent autophagic degradation induced by starvation and that it was colocalized with BmATG8.Lastly,we demonstrated that BmDREDD attenuated autophagy and BmCasp8L suppressed BmDREDD-mediated cleavage of BmATG6.Taken together,our results demonstrated that BmCasp8L is a novel proautophagic molecule which suppresses BmDREDD-mediated cleavage of BmATG6 and is a target for autophagy.展开更多
The host antimicrobial immune response relies on a complex interplay of molecular mechanisms to effectively combat microbial infections.Herein,we investigate the functional role of Cullin-3(Cul3),one critical constitu...The host antimicrobial immune response relies on a complex interplay of molecular mechanisms to effectively combat microbial infections.Herein,we investigate the functional role of Cullin-3(Cul3),one critical constituent of Cullin-RING ubiquitin ligases,in the Drosophila melanogaster(fruit fly)antimicrobial immune defense.Weshow that silencing of Cul3 leads to a decreased induction of antimicrobial peptides and high mortality in adult flies after bacterial infection.Through biochemical approaches,we demonstrate that Cul3 predominantly relies on its BTB-binding domain and neddylation domain to physically associate with death-associated inhibitor of apoptosis 2(Diap2).Importantly,Cul3 ameliorates the Diap2-mediated ubiquitination of death-related ced-3/Nedd2-like caspase(Dredd),a process essential for robust immune deficiency signaling upon bacterial infection.Taken together,our findings highlight a previously unrecognized regulatory axis of Cul3/Diap2/Dredd in the fly antimicrobial immune defense,providing potential insights into therapeutic strategies for combating bacterial infections in humans.展开更多
基金supported by grants from the National Natural Science Foundation of China(No.31672495)Natural Science Foundation of Chongqing,China(cstc2020jcyj-msxmX0193).
文摘Autophagy plays an important role in tissue remodeling during insect development.The interplay between autophagy-related(ATG)proteins and caspases regulates the autophagic activity of ATGs,thereby modulating the process of autophagy.Our previous study characterized BmCaspase-8-like(BmCasp8L)as a caspase suppressor that inhibits apoptosis and immune signaling by suppressing the activation of death-related ced-3/Nedd2-like caspase(DREDD),a caspase-8 homolog in silkworm.In this study,we explored the regulatory role of BmCasp8L in autophagy.We found that the expression of Bmcasp8l increased from the late spinning stage to the pupa stage in the posterior silk gland(PSG),correlating with the expression patterns of Bmatg8 and Bmatg6.RNA interference-mediated downregulation of BmCasp8L expression significantly decreased starvation-induced autophagic influx as determined by the levels of BmATG8–phosphatidylethanolamine and the percentage of cells displaying punctate enhanced green fluorescent protein-BmATG8.Conversely,the overexpression of BmCasp8L significantly increased autophagic influx.We also found that BmCasp8L underwent autophagic degradation induced by starvation and that it was colocalized with BmATG8.Lastly,we demonstrated that BmDREDD attenuated autophagy and BmCasp8L suppressed BmDREDD-mediated cleavage of BmATG6.Taken together,our results demonstrated that BmCasp8L is a novel proautophagic molecule which suppresses BmDREDD-mediated cleavage of BmATG6 and is a target for autophagy.
基金supported by grants from the National Natural Science Foundation of China(32100702).
文摘The host antimicrobial immune response relies on a complex interplay of molecular mechanisms to effectively combat microbial infections.Herein,we investigate the functional role of Cullin-3(Cul3),one critical constituent of Cullin-RING ubiquitin ligases,in the Drosophila melanogaster(fruit fly)antimicrobial immune defense.Weshow that silencing of Cul3 leads to a decreased induction of antimicrobial peptides and high mortality in adult flies after bacterial infection.Through biochemical approaches,we demonstrate that Cul3 predominantly relies on its BTB-binding domain and neddylation domain to physically associate with death-associated inhibitor of apoptosis 2(Diap2).Importantly,Cul3 ameliorates the Diap2-mediated ubiquitination of death-related ced-3/Nedd2-like caspase(Dredd),a process essential for robust immune deficiency signaling upon bacterial infection.Taken together,our findings highlight a previously unrecognized regulatory axis of Cul3/Diap2/Dredd in the fly antimicrobial immune defense,providing potential insights into therapeutic strategies for combating bacterial infections in humans.
