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The Sirtuin SIRT6 Represses Expression of Cachexia‐Associated Cytokine Myostatin by Blocking its NF‐kB‐Dependent Gene Transcription
Author(s) -
Gupta Mahesh,
Samant Sadhana,
Bao Riyue,
Pillai Vinodkumar
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.1009.11
Subject(s) - myostatin , sirt6 , myod , myocyte , endocrinology , biology , c2c12 , cachexia , medicine , muscle atrophy , myogenin , skeletal muscle , wasting , cancer research , sirtuin , microbiology and biotechnology , myogenesis , cancer , nad+ kinase , biochemistry , enzyme
Loss of body weight and involuntary muscle wasting (cachexia) is associated with many terminal diseases, including heart failure, cancer, COPD and liver cirrhosis. One of the most critical mediators of cachexia‐associated muscle wasting is myostatin (Mstn), a member of the TGFβ superfamily, which is secreted from muscle cells. Mstn binds to activin receptor‐IIB and suppresses both muscle cell growth and differentiation. SIRT6 is a chromatin associated NAD‐dependent deacetylase, which has been shown to regulate wide range of cellular processes, and considered to be an anti‐aging molecule. While SIRT6KO mice display muscle atrophy, retarded body size, metabolic defects and development of heart failure, over expression of SIRT6 has been shown to extend lifespan of mice. This study was undertaken to study the role of SIRT6 in growth and wasting of skeletal muscle. Methods and Results We prepared RNA from SIRT6 knocked down neonatal rat cardiac myocytes and subjected it to deep RNA sequencing. The results showed that SIRT6 deficiency led to increased expression of Mstn (22 fold) and activin receptor‐IIB (3 fold), together with decreased expression of myosin heavy chain proteins (18 fold). These results were confirmed by western blotting. We also detected significantly increased levels of Mstn in the condition media of SIRT6 knocked‐down cardiomyocytes, compared to media prepared from control cells. To test the functional significance of Mstn secreted from cardiomyocytes, we exposed C2C12 cells to media prepared from SIRT6 deficient and control cells. The condition media of SIRT6 deficient cells, but not of control cells, blocked the C2C12 cells differentiation, as measured by expression levels of myosin heavy chain protein, thus confirming that the Mstn secreted from cardiomyocytes was functionally active. To underpin the mechanism through which SIRT6 controls the expression of Mstn gene we performed the ChIP assay. We found that SIRT6 was bound to the Mstn promoter at the NF‐kB binding sites. The treatment of cells with a NF‐kB inhibitor, Bay‐11‐7082, significantly reduced the occupancy of SIRT6 to the Mstn promoter, thus suggesting that SIRT6 suppresses Mstn expression by negatively regulating NF‐kB‐dependent transcription of Mstn gene promoter. Conclusion Loss of SIRT6 has been linked with development of many chronic diseases. Our data suggest that induction of cachexia with these diseases may be resulting from increased expression of Mstn due to SIRT6 deficiency. Therefore, SIRT6 activation may be considered a therapeutic intervention for the management of cachexia. Support or Funding Information NIH RO1‐HL117041 NIH RO1‐HL111455