Abstract
The C-terminus of SIRT1 can be cleaved by cathepsin B at amino acid H533 to generate a lower-functioning, N-terminally intact 75 kDa polypeptide (75SIRT1) that might be involved in age-related pathologies. However, the mechanisms underlying cathepsin B docking to and cleavage of SIRT1 are unclear. Here, we first identified several 75SIRT1 variants that are augmented with aging correlatively with increased cathepsin B levels in various mouse tissues, highlighting the possible role of this cleavage event in agerelated pathologies. Then, based onH533 point mutation and structural modeling, we generated a functionally intact ΔSIRT1 mutant, lacking the internal amino acids 528-543 (a predicted C-terminus loop domain), which exhibits resistance to cathepsin B cleavage in vitro and in cell cultures. Finally, we showed that cells expressing ΔSIRT1 under pro-inflammatory stress are more likely to undergo caspase 9- dependent apoptosis than those expressing 75SIRT1. Thus, our data suggest that the 15-amino acid predicted loop motif embedded in the C-terminus of SIRT1 is susceptible to proteolytic cleavage by cathepsin B, leading to the formation of several N-terminally intact SIRT1 truncated variants in various aging mouse tissues.
Original language | English |
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Article number | jcs.214973 |
Journal | Journal of Cell Science |
Volume | 131 |
Issue number | 16 |
DOIs | |
State | Published - 1 Aug 2018 |
Bibliographical note
Publisher Copyright:© 2018. Published by The Company of Biologists Ltd.
Keywords
- Caspase 9
- Cathepsin B
- Cytochrome C
- Inflamm-aging
- SIRT1