A predicted unstructured C-terminal loop domain in SIRT1 is required for cathepsin B cleavage

Ashok Kumar, Yutti Daitsh, Louisa Ben-Aderet, Omar Qiq, Jinan Elayyan, George Batshon, Eli Reich, Yonatan Harel Maatuf, Stanislav Engel, Mona Dvir-Ginzberg*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


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 languageAmerican English
Article numberjcs.214973
JournalJournal of Cell Science
Issue number16
StatePublished - 1 Aug 2018

Bibliographical note

Publisher Copyright:
© 2018. Published by The Company of Biologists Ltd.


  • Caspase 9
  • Cathepsin B
  • Cytochrome C
  • Inflamm-aging
  • SIRT1


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