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Updated: Oct 1, 2025
A Doxorubicin-induced Cardiomyopathy Model in Adult Zebrafish
Published on: June 7, 2018
SIRT1 in the cardiomyocyte counteracts doxorubicin-induced cardiotoxicity via regulating histone H2AX
Atsushi Kuno1, Ryusuke Hosoda1, Miki Tsukamoto1
1Department of Pharmacology, Sapporo Medical University School of Medicine, South-1, West-17, Chuo-ku, Sapporo 060-8556, Japan.
Aims:
Cardiotoxicity by doxorubicin predicts worse prognosis of patients. Accumulation of damaged DNA has been implicated in doxorubicin-induced cardiotoxicity. SIRT1, an NAD+-dependent histone/protein deacetylase, protects cells by deacetylating target proteins. We investigated whether SIRT1 counteracts doxorubicin-induced cardiotoxicity by mediating Ser139 phosphorylation of histone H2AX, a critical signal of the DNA damage response.
Methods And Results:
Doxorubicin (5 mg/kg per week, x4) was administered to mice with intact SIRT1 (Sirt1f/f) and mice that lack SIRT1 activity in cardiomyocytes (Sirt1f/f;MHCcre/+). Reductions in left ventricular fractional shortening and ejection fraction by doxorubicin treatment were more severe in Sirt1f/f;MHCcre/+ than in Sirt1f/f. Myocardial expression level of type-B natriuretic peptide was 2.5-fold higher in Sirt1f/f;MHCcre/+ than in Sirt1f/f after doxorubicin treatment. Sirt1f/f;MHCcre/+ showed larger fibrotic areas and higher nitrotyrosine levels in the heart after doxorubicin treatment. Although doxorubicin-induced DNA damage evaluated by TUNEL staining was enhanced in Sirt1f/f;MHCcre/+, the myocardium from Sirt1f/f;MHCcre/+ showed blunted Ser139 phosphorylation of H2AX by doxorubicin treatment. In H9c2 cardiomyocytes, SIRT1 knockdown attenuated Ser139 phosphorylation of H2AX, increased DNA damage, and enhanced caspase-3 activation under doxorubicin treatment. Immunostaining revealed that acetylation level of H2AX at Lys5 was higher in hearts from Sirt1f/f;MHCcre/+. In H9c2 cells, acetyl-Lys5-H2AX level was increased by SIRT1 knockdown and reduced by SIRT1 overexpression. Ser139 phosphorylation in response to doxorubicin treatment was blunted in a mutant H2AX with substitution of Lys5 to Gln (K5Q) that mimics acetylated lysine compared with that in wild-type H2AX. Expression of K5Q-H2AX as well as S139A-H2AX, which cannot be phosphorylated at Ser139, augmented doxorubicin-induced caspase-3 activation. Treatment of mice with resveratrol, a SIRT1 activator, attenuated doxorubicin-induced cardiac dysfunction, which was associated with a reduction in acetyl-Lys5-H2AX level and a preserved phospho-Ser139-H2AX level.
Conclusion:
These findings suggest that SIRT1 counteracts doxorubicin-induced cardiotoxicity by mediating H2AX phosphorylation through its deacetylation in cardiomyocytes.
Insights
SIRT1 protects the heart from doxorubicin cardiotoxicity by regulating DNA damage response. SIRT1 deacetylates histone H2AX, promoting its phosphorylation and mitigating cardiac dysfunction.
Area of Science:
- Cardiology
- Molecular Biology
- Oncology
Background:
- Doxorubicin (DOX) chemotherapy can cause cardiotoxicity, leading to poor patient prognosis.
- Accumulated DNA damage in cardiomyocytes is a key factor in DOX-induced cardiotoxicity.
- SIRT1, a protein deacetylase, plays a protective role in cellular stress responses.
Purpose of the Study:
- To investigate if SIRT1 can counteract doxorubicin-induced cardiotoxicity.
- To determine if SIRT1 mediates the phosphorylation of histone H2AX (a DNA damage marker) in response to doxorubicin.
- To elucidate the role of SIRT1 in the DNA damage response pathway within cardiomyocytes.
Main Methods:
- Administered doxorubicin to mice with intact and cardiomyocyte-specific SIRT1 knockout.
- Assessed cardiac function (fractional shortening, ejection fraction) and cardiac damage markers (BNP, fibrosis, nitrotyrosine).
- Evaluated DNA damage (TUNEL), histone H2AX phosphorylation (p-Ser139 H2AX), and H2AX acetylation (acetyl-Lys5 H2AX) in cardiac tissue and H9c2 cells.
Main Results:
- DOX-induced cardiotoxicity and DNA damage were more severe in mice lacking cardiomyocyte SIRT1.
- SIRT1 deficiency blunted doxorubicin-induced H2AX Ser139 phosphorylation and increased H2AX Lys5 acetylation.
- SIRT1 activation with resveratrol attenuated DOX cardiotoxicity, preserving H2AX phosphorylation.
- Knockdown of SIRT1 in H9c2 cells increased DNA damage and caspase-3 activation under DOX treatment.
Conclusions:
- SIRT1 plays a crucial protective role against doxorubicin-induced cardiotoxicity.
- SIRT1 counteracts DOX cardiotoxicity by promoting H2AX phosphorylation via deacetylation of H2AX at Lys5.
- Targeting SIRT1 may offer a therapeutic strategy to prevent or treat chemotherapy-induced heart damage.
