Deacetylation of FoxO by Sirt1 plays an essential role in mediating starvation-induced autophagy in cardiac myocytes

Nirmala Hariharan, Yasuhiro Maejima, Jun Nakae, Jihye Paik, Ronald A. Depinho, Junichi Sadoshima

Research output: Contribution to journalArticle

342 Citations (Scopus)

Abstract

Rationale: Autophagy, a bulk degradation process of cytosolic proteins and organelles, is protective during nutrient starvation in cardiomyocytes (CMs). However, the underlying signaling mechanism mediating autophagy is not well understood. Objective: We investigated the role of FoxOs and its posttranslational modification in mediating starvation-induced autophagy. Methods and results: Glucose deprivation (GD) increased autophagic flux in cultured CMs, as evidenced by increased mRFP-GFP-LC3 puncta and decreases in p62, which was accompanied by upregulation of Sirt1 and FoxO1. Overexpression of either Sirt1 or FoxO1 was sufficient for inducing autophagic flux, whereas both Sirt1 and FoxO1 were required for GD-induced autophagy. GD increased deacetylation of FoxO1, and Sirt1 was required for GD-induced deacetylation of FoxO1. Overexpression of FoxO1(3A/LXXAA), which cannot interact with Sirt1, or p300, a histone acetylase, increased acetylation of FoxO1 and inhibited GD-induced autophagy. FoxO1 increased expression of Rab7, a small GTP-binding protein that mediates late autophagosome-lysosome fusion, which was both necessary and sufficient for mediating FoxO1-induced increases in autophagic flux. Although cardiac function was maintained in control mice after 48 hours of food starvation, it was significantly deteriorated in mice with cardiac-specific overexpression of FoxO1(3A/LXXAA), those with cardiac-specific homozygous deletion of FoxO1 (c-FoxO1), and beclin1 mice, in which autophagy is significantly inhibited. Conclusions: These results suggest that Sirt1-mediated deacetylation of FoxO1 and upregulation of Rab7 play an important role in mediating starvation-induced increases in autophagic flux, which in turn plays an essential role in maintaining left ventricular function during starvation.

Original languageEnglish (US)
Pages (from-to)1470-1482
Number of pages13
JournalCirculation Research
Volume107
Issue number12
DOIs
StatePublished - Dec 10 2010
Externally publishedYes

Fingerprint

Autophagy
Starvation
Cardiac Myocytes
Glucose
Up-Regulation
Food
Post Translational Protein Processing
Acetylation
Lysosomes
Left Ventricular Function
GTP-Binding Proteins
Organelles
Proteins

Keywords

  • autophagy
  • deacetylation
  • FoxO
  • Rab7
  • Sirt1
  • starvation

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

Cite this

Deacetylation of FoxO by Sirt1 plays an essential role in mediating starvation-induced autophagy in cardiac myocytes. / Hariharan, Nirmala; Maejima, Yasuhiro; Nakae, Jun; Paik, Jihye; Depinho, Ronald A.; Sadoshima, Junichi.

In: Circulation Research, Vol. 107, No. 12, 10.12.2010, p. 1470-1482.

Research output: Contribution to journalArticle

Hariharan, Nirmala ; Maejima, Yasuhiro ; Nakae, Jun ; Paik, Jihye ; Depinho, Ronald A. ; Sadoshima, Junichi. / Deacetylation of FoxO by Sirt1 plays an essential role in mediating starvation-induced autophagy in cardiac myocytes. In: Circulation Research. 2010 ; Vol. 107, No. 12. pp. 1470-1482.
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AU - Paik, Jihye

AU - Depinho, Ronald A.

AU - Sadoshima, Junichi

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AB - Rationale: Autophagy, a bulk degradation process of cytosolic proteins and organelles, is protective during nutrient starvation in cardiomyocytes (CMs). However, the underlying signaling mechanism mediating autophagy is not well understood. Objective: We investigated the role of FoxOs and its posttranslational modification in mediating starvation-induced autophagy. Methods and results: Glucose deprivation (GD) increased autophagic flux in cultured CMs, as evidenced by increased mRFP-GFP-LC3 puncta and decreases in p62, which was accompanied by upregulation of Sirt1 and FoxO1. Overexpression of either Sirt1 or FoxO1 was sufficient for inducing autophagic flux, whereas both Sirt1 and FoxO1 were required for GD-induced autophagy. GD increased deacetylation of FoxO1, and Sirt1 was required for GD-induced deacetylation of FoxO1. Overexpression of FoxO1(3A/LXXAA), which cannot interact with Sirt1, or p300, a histone acetylase, increased acetylation of FoxO1 and inhibited GD-induced autophagy. FoxO1 increased expression of Rab7, a small GTP-binding protein that mediates late autophagosome-lysosome fusion, which was both necessary and sufficient for mediating FoxO1-induced increases in autophagic flux. Although cardiac function was maintained in control mice after 48 hours of food starvation, it was significantly deteriorated in mice with cardiac-specific overexpression of FoxO1(3A/LXXAA), those with cardiac-specific homozygous deletion of FoxO1 (c-FoxO1), and beclin1 mice, in which autophagy is significantly inhibited. Conclusions: These results suggest that Sirt1-mediated deacetylation of FoxO1 and upregulation of Rab7 play an important role in mediating starvation-induced increases in autophagic flux, which in turn plays an essential role in maintaining left ventricular function during starvation.

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