Limonin stabilises sirtuin 6 (SIRT6) by activating ubiquitin specific peptidase 10 (USP10) in cardiac hypertrophy

Abstract

Background and Purpose: Limonin, a naturally occurring tetracyclic triterpenoid, has extensive pharmacological effects. Its role in cardiac hypertrophy remains to be elucidated. We investigated its effects on cardiac hypertrophy along with the potential mechanisms involved.Experimental Approach: The effects of limonin on cardiac hypertrophy in C57/BL6 mice caused by aortic banding, plus neonatal rat cardiac myocytes (NRCMs) stimulated with phenylephrine to induce cardiomyocyte hypertrophy in vitro were investigated.Key Results: Limonin markedly improved the cardiac function and heart weight in aortic banded mice. Limonin-treated mice and NRCMs also produced fewer cardiac hypertrophy markers than those treated with the vehicle in the hypertrophic groups.Sustained aortic banding-or phenylephrine-stimulation impaired cardiac sirtuin 6 (SIRT6) protein levels, which were partially reversed by limonin associated with enhanced activity of PPARα. Sirt6 siRNA inhibited the anti-hypertrophic effects of limonin in vitro. Interestingly, limonin did not influence Sirt6 mRNA levels, but regulated ubiquitin levels. Thus, the protein biosynthesis inhibitor, cycloheximide and proteasome inhibitor, MG-132, were used to determine SIRT6 protein expression levels.Under phenylephrine stimulation, limonin increased SIRT6 protein levels in the presence of cycloheximide, but it did not influence SIRT6 expression in the presence of MG-132, suggesting that limonin promotes SIRT6 levels by inhibiting its ubiquitination degradation. Furthermore, limonin inhibited the degradation of SIRT6 by activating ubiquitin-specific peptidase 10 (USP10), while Usp10 siRNA prevented the beneficial effects of limonin. Conclusion and Implications:Limonin mediates the ubiquitination and degradation of SIRT6 by activating USP10, providing an attractive therapeutic target for cardiac hypertrophy.

HINT2 protects against pressure overload‐induced cardiac remodelling through mitochondrial pathways

“…Following the administration of intraperitoneal sodium pentobarbital anaesthesia (50 mg/kg, once), male mice (8–10 weeks old, weighing 23.5–27.5 g) were randomly assigned to groups to undergo AB surgery, as previously described. 17 After the induction of anaesthesia, the left thorax of each mouse was opened, and the thoracic aorta was carefully separated under a microscope. Subsequently, a 27‐gauge needle was positioned alongside the separated aortic segment, and the aorta was ligated by tying a slipknot around it using 7–0 silk sutures.…”

“…Subsequently, the sections were subjected to haematoxylin–eosin staining (H&E), picrosirius red staining (PSR) and terminal deoxynucleotidyl transferaseerminal deoxynucleotidyl transferase‐mediated dUTP nick end labeling (TUNEL) staining as described in our previous study to assess the cross‐sectional area (CSA), volume of fibrosis in the heart, and cell death, respectively. 17 , 19 Additionally, cellular areas were calculated in more than 100 cells, the volume of fibrosis in the heart was measured in over 60 fields, the percentages of apoptotic cells were calculated by at least three independent individuals in a blinded manner. The data were then analysed using computerized analytic program (Image‐Pro Plus 6.0, Media Cybernetics, Bethesda, USA).…”

The role of mammalian Sirtuin 6 in cardiovascular diseases and diabetes mellitus

“…Besides, Sirt6, depending on its deacetylase activity, represses the expression of nuclear factor of activated T cells c4 (NFATc4) and protects against cardiac hypertrophy ( Li et al, 2019 ). Additionally, a study reported of important roles of Sirt6 in regulating in cardiac hypertrophy associated with deubiquitinase ubiquitin-specific protease 10 (USP10) ( Liu et al, 2022 ). The USP10 attenuates aortic constriction-induced cardiac hypertrophy by directly regulating Sirt6 levels ( Zhang DH.…”

SIRT6 mediated histone H3K9ac deacetylation involves myocardial remodelling through regulating myocardial energy metabolism in TAC mice

“…Sirtuin 6 (SIRT6) is a member of the III class histone deacetylase (HDAC) Sirtuin family and a highly specific histone H3 deacetylase that targets histone 3 acetylated at Lys‐9 (H3K9), Lys‐56 (H3K56) and Lys‐18 (H3K18) 16 . Mice with heart‐specific knockout of SIRT6 spontaneously develop cardiac hypertrophy and heart failure, while SIRT6 transgenic overexpression blocks pressure overload and agonist‐induced myocardial hypertrophy 17,18 . SIRT6 has an inhibitory effect on mitochondrial damage in cardiomyocytes, 19 but the specific mechanism and regulatory targets are still unclear.…”

“…16 Mice with heart-specific knockout of SIRT6 spontaneously develop cardiac hypertrophy and heart failure, while SIRT6 transgenic overexpression blocks pressure overload and agonist-induced myocardial hypertrophy. 17,18 SIRT6 has an inhibitory effect on mitochondrial damage in cardiomyocytes, 19 but the specific mechanism and regulatory targets are still unclear. Increasing evidence has demonstrated that SIRT6 functions as a negative regulator of cardiac hypertrophy.…”