Department of Molecular, Cell and Cancer Biology; Graduate School of Biomedical Sciences, Cancer Biology Program
Biochemistry, Biophysics, and Structural Biology | Cell and Developmental Biology | Genetics and Genomics
Apoptosis is an evolutionary conserved cell death mechanism, which requires activation of initiator and effector caspases. The Drosophila initiator caspase Dronc, the ortholog of mammalian Caspase-2 and Caspase-9, has an N-terminal CARD domain that recruits Dronc into the apoptosome for activation. In addition to its role in apoptosis, Dronc also has non-apoptotic functions such as compensatory proliferation. One mechanism to control the activation of Dronc is ubiquitylation. However, the mechanistic details of ubiquitylation of Dronc are less clear. For example, monomeric inactive Dronc is subject to non-degradative ubiquitylation in living cells, while ubiquitylation of active apoptosome-bound Dronc triggers its proteolytic degradation in apoptotic cells. Here, we examined the role of non-degradative ubiquitylation of Dronc in living cells in vivo, i.e. in the context of a multi-cellular organism. Our in vivo data suggest that in living cells Dronc is mono-ubiquitylated on Lys78 (K78) in its CARD domain. This ubiquitylation prevents activation of Dronc in the apoptosome and protects cells from apoptosis. Furthermore, K78 ubiquitylation plays an inhibitory role for non-apoptotic functions of Dronc. We provide evidence that not all of the non-apoptotic functions of Dronc require its catalytic activity. In conclusion, we demonstrate a mechanism whereby Dronc's apoptotic and non-apoptotic activities can be kept silenced in a non-degradative manner through a single ubiquitylation event in living cells.
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Copyright © 2017 Kamber Kaya et al.
DOI of Published Version
PLoS Genet. 2017 Feb 16;13(2):e1006438. doi: 10.1371/journal.pgen.1006438. eCollection 2017 Feb. Link to article on publisher's site
Kamber Kaya HE, Ditzel M, Meier P, Bergmann A. (2017). An inhibitory mono-ubiquitylation of the Drosophila initiator caspase Dronc functions in both apoptotic and non-apoptotic pathways. Open Access Articles. https://doi.org/10.1371/journal.pgen.1006438. Retrieved from https://escholarship.umassmed.edu/oapubs/3093
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