Sirt1 deficiency, specifically in fibroblasts, decreases apoptosis resistance and is associated with resolution of lung-fibrosis

Raanan Bulvik, Raphael Breuer, Mona Dvir-Ginzberg, Eli Reich, Neville Berkman, Shulamit B. Wallach-Dayan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

In contrast to normal regenerating tissue, resistance to Fas-and FasL-positive T cell-induced apoptosis were detected in myofibroblasts from fibrotic-lungs of humans and mice following bleomycin (BLM) exposure. In this study we show, decreased FLIP expression in lung-tissues with resolution of BLM-induced fibrosis and in isolated-lung fibroblasts, with decreased resistance to apoptosis. Using a FLIP-expression vector or a shFLIP-RNA, we further confirmed the critical need for FLIP to regain/lose susceptibility of fibrotic-lung myofibroblast to Fas-induced apoptosis. Our study further show that FLIP is regulated by SIRT1 (Sirtuin 1) deacetylase. Chimeric mice, with SIRT1-deficiency in deacetylase domain (H355Y-Sirt1y/y), specifically in mesenchymal cells, were not only protected from BLM-induced lung fibrosis but, as assessed following Ku70 immunoprecipitation, had also decreased Ku70-deacetylation, decreasedKu70/FLIP complex, and decreased FLIP levels in their lung myofibroblasts. In addition, myofibroblasts isolated from lungs of BLM-treated miR34a-knockout mice, exposed to a miR34a mimic, which we found here to downregulate SIRT1 in the luciferase assay, had a decreased Ku70-deacetylation indicating decrease in SIRT1 activity. Thus, SIRT1 may mediate, miR34a-regulated, persistent FLIP levels by deacetylation of Ku70 in lung myofibroblasts, promoting resistance to cell-death and lung fibrosis.

Original languageAmerican English
Article number996
Pages (from-to)1-12
Number of pages12
JournalBiomolecules
Volume10
Issue number7
DOIs
StatePublished - Jul 2020
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2020 by the authors. Licensee MDPI, Basel, Switzerland.

Keywords

  • Cell-death
  • FLIP
  • IPF-resolution
  • Ku70
  • Myofibroblasts
  • SIRT1

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