Zerumbone prevents pressure overload-induced left ventricular systolic dysfunction by inhibiting cardiac hypertrophy and fibrosis

Fibroblast-specific PRMT5 deficiency suppresses cardiac fibrosis and left ventricular dysfunction in male mice

Protein arginine methyltransferase 5 (PRMT5) is a well-known epigenetic regulatory enzyme. However, the role of PRMT5-mediated arginine methylation in gene transcription related to cardiac fibrosis is unknown. Here we show that fibroblast-specific deletion of PRMT5 significantly reduces pressure overload-induced cardiac fibrosis and improves cardiac dysfunction in male mice. Both the PRMT5-selective inhibitor EPZ015666 and knockdown of PRMT5 suppress α-smooth muscle actin (α-SMA) expression induced by transforming growth factor-β (TGF-β) in cultured cardiac fibroblasts. TGF-β stimulation promotes the recruitment of the PRMT5/Smad3 complex to the promoter site of α-SMA. It also increases PRMT5-mediated H3R2 symmetric dimethylation, and this increase is inhibited by Smad3 knockdown. TGF-β stimulation increases H3K4 tri-methylation mediated by the WDR5/MLL1 methyltransferase complex, which recognizes H3R2 dimethylation. Finally, treatment with EPZ015666 significantly improves pressure overload-induced cardiac fibrosis and dysfunction. These findings suggest that PRMT5 regulates TGF-β/Smad3-dependent fibrotic gene transcription, possibly through histone methylation crosstalk, and plays a critical role in cardiac fibrosis and dysfunction.

6-Shogaol, an Active Component of Ginger, Inhibits p300 Histone Acetyltransferase Activity and Attenuates the Development of Pressure-Overload-Induced Heart Failure

Hypertrophic stress-induced cardiac remodeling is a compensatory mechanism associated with cardiomyocyte hypertrophy and cardiac fibrosis. Continuation of this response eventually leads to heart failure. The histone acetyltransferase p300 plays an important role in the development of heart failure, and may be a target for heart failure therapy. The phenolic phytochemical 6-shogaol, a pungent component of raw ginger, has various bioactive effects; however, its effect on cardiovascular diseases has not been investigated. One micromolar of 6-shogaol suppressed phenylephrine (PE)-induced increases in cardiomyocyte hypertrophy in rat primary cultured cardiomyocytes. In rat primary cultured cardiac fibroblasts, 6-shogaol suppressed transforming growth factor-beta (TGF-β)-induced increases in L-proline incorporation. It also blocked PE- and TGF-β-induced increases in histone H3K9 acetylation in the same cells and in vitro. An in vitro p300-HAT assay revealed that 6-shogaol suppressed histone acetylation. The mice underwent transverse aortic constriction (TAC) surgery, and were administered 0.2 or 1 mg/kg of 6-shogaol daily for 8 weeks. 6-shogaol prevented TAC-induced systolic dysfunction and cardiac hypertrophy in a dose-dependent manner. Furthermore, it also significantly inhibited TAC-induced increases in histone H3K9 acetylation. These results suggest that 6-shogaol may ameliorate heart failure through a variety of mechanisms, including the inhibition of p300-HAT activity.

Strophioblachins A-K, Structurally Intriguing Diterpenoids from Strophioblachia fimbricalyx with Potential Anticardiac Hypertrophic Inhibitory Activity

Three new rearranged diterpenoids, strophioblachins A-C (1-3), eight new diterpenoids, strophioblachins D-K (4-11), and seven previously described diterpenoids (12-18) were purified from the aerial parts of Strophioblachia fimbricalyx. Compounds 1 and 2 contain a rare 6/6/5/6 ring system, while 3 has an uncommon tricyclo[4.4.0.0^8,9]tridecane-bridged unit, and their diterpenoid skeletons are being reported for the first time. Utilizing spectroscopic and HRESIMS data analysis, the structures of the new compounds (1-11) were established, and ECD and ¹³C NMR calculations were used to confirm the relative and absolute configurations of 11 and 9. The absolute configurations of compounds 1, 3, and 10 were established using single-crystal X-ray diffraction. The results of testing for anticardiac hypertrophic activity demonstrated that compounds 10 and 15 dose-dependently lowered the mRNA expression of Nppa and Nppb. Protein levels were confirmed by Western blotting, which also demonstrated that compounds 10 and 15 lowered the expression of the hypertrophic marker ANP. The cytotoxic activity against neonatal rat cardiomyocytes was assayed in vitro by the CCK-8 and ELISA methods, and the results showed that compounds 10 and 15 were only very weakly active in the range.

Calycosin reduces myocardial fibrosis and improves cardiac function in post-myocardial infarction mice by suppressing TGFBR1 signaling pathways

BACKGROUND

Excessive myocardial fibrosis is the pathological basis of heart failure following myocardial infarction (MI). Although calycosin improves cardiac function, its effect on cardiac fibrosis and cardiac function after MI in mice and its precise mechanism remain unclear.

PURPOSE

Here, we firstly investigated the effects of calycosin on cardiac fibrosis and ventricular function in mice after MI and the role of transforming growth factor-beta receptor 1 (TGFBR1) signaling in the amelioration of cardiac fibrosis and ventricular function.

METHODS

In vivo effects of calycosin on cardiac structure and function in mice with MI induced by left anterior descending coronary artery ligation were determined by hematoxylin and eosin staining, Masson trichrome staining, and echocardiography. The molecular mechanism of the interaction between TGFBR1 and calycosin was investigated using molecular docking, molecular dynamics (MD) simulation, surface plasmon resonance imaging (SPRi), immunohistochemistry, and western blotting (WB). Subsequently, cardiac-specific Tgfbr1 knockout mice were used to verify the effects of calycosin. The effect of calycosin on primary cardiac fibroblasts (CFs) proliferation and collagen deposition was detected using cell counting (CCK-8), EdU assay, and WB in vitro. CFs infected with an adenovirus that encodes TGFBR1 were used to verify the effects of calycosin.

RESULTS

In vivo, calycosin attenuated myocardial fibrosis and cardiac dysfunction following MI in a dose-dependent pattern. Calycosin-TGFBR1 complex was found to have a binding energy of -9.04 kcal/mol based on molecular docking. In addition, calycosin bound steadily in the cavity of TGFBR1 during the MD simulation. Based on SPRi results, the solution equilibrium dissociation constant for calycosin and TGFBR1 was 5.11 × 10^-5 M. Calycosin inhibited the expression of TGFBR1, Smad2/3, collagen I, and collagen III. The deletion of TGFBR1 partially counteracted these effects. In vitro, calycosin suppressed CFs proliferation and collagen deposition after TGF-β1 stimulation by suppressing the TGFBR1 signaling pathway. The suppressive effects of calycosin were partially rescued by overexpression of TGFBR1.

CONCLUSION

Calycosin attenuates myocardial fibrosis and cardiac dysfunction following MI in mice in vivo via suppressing the TGFBR1 signaling pathway. Calycosin suppresses CFs proliferation and collagen deposition induced by TGF-β1 via inhibition of the TGFBR1 signaling pathway in vitro.

Zerumbone, a humulane sesquiterpene from Syringa pinnatifolia, attenuates cardiac fibrosis by inhibiting of the TGF-β1/Smad signaling pathway after myocardial infarction in mice

BACKGROUND

Zerumbone (ZER) is a humulane sesquiterpene isolated from Syringa pinnatifolia Hemsl., a representative Mongolian herbal medicine that is used to treat cardiovascular diseases. Cardiac fibrosis is a common pathological process in cardiovascular disease that results from the excessive accumulation of extracellular matrix (ECM), and the transforming growth factor (TGF)-β/Smad pathway is a canonical signaling pathway that directly induces expressions of ECM-related genes. Currently, the cardioprotective effect and underlying mechanisms of ZER on the inhibition of cardiac fibrosis are not well known.

PURPOSE

To explore the cardioprotective properties and pharmacological mechanism of ZER against cardiac fibrosis via the TGF-β1/Smad signaling pathway.

METHODS

Myocardial infarction (MI) model was induced by ligation of the left anterior descending coronary artery in ICR mice. The mice were randomly divided into six groups: sham, model, low-dose ZER (ZER-L), medium-dose ZER (ZER-M), high-dose ZER (ZER-H) and fosinopril. Mice in each group were intragastrically administered treatments for 21 days, and cardiac function was evaluated by 2D echocardiography. The pathological structure of the heart was examined by hematoxylin and eosin (HE) and Masson staining. Content of collagen I and collagen III were assessed by immunofluorescence methods. The inhibitory effect of ZER on TGF-β1 protein expression was predicted by molecular docking technology. Reverse transcriptase polymerase chain reaction (RT-PCR) and western blotting were used to measure the levels of genes and proteins expressed in the TGF-β1/Smad signaling pathway and MMPs. TGF-β1-treated cardiac fibroblasts (CFs) of neonatal SD rats were adopted for in vitro studies.

RESULTS

Cardiac ejection fraction (EF) and fractional shortening (FS) in the model group were markedly decreased compared with those in the sham group, indicating that the MI model was successfully established. ZER and fosinopril elevated EF and FS values, suggesting cardioprotective effects. Pathological staining and immunofluorescence analysis showed that the content of collagen I and collagen III increased in the cardiac tissue of mice in model group, while ZER treatment obviously reduced collagen levels. The molecular docking simulations predicted the hydrophobic interactions between ZER and TGF-β1. In addition, the expression of TGF-β1, p-Smad2/3 and MMPs in the ZER treatment group was significantly decreased compared with the model group. In vitro studies further confirmed that α-smooth muscle actin (α-SMA) and p-Smad2/3 increased markedly in cardiac fibroblasts after incubation with TGF-β1, and treatment with ZER suppressed the expression of α-SMA and TGF-β1 downstream proteins in cardiac fibroblasts.

CONCLUSION

ZER rescues cardiac function by attenuating cardiac fibrosis, and the antifibrotic effect may be mediated by blocking the TGF-β1/Smad pathway.