Sorafenib induces cardiotoxicity through RBM20-mediated alternative splicing of sarcomeric and mitochondrial genes.

Sorafenib, a multi-targeted tyrosine kinase inhibitor, is a first-line treatment for advanced solid tumors, but it induces many adverse cardiovascular events, including myocardial infarction and heart failure. These cardiac defects can be mediated by alternative splicing of genes critical for heart function. Whether alternative splicing plays a role in sorafenib-induced cardiotoxicity remains unclear. Transcriptome of rat hearts or human cardiomyocytes treated with sorafenib was analyzed and validated to define alternatively spliced genes and their impact on cardiotoxicity. In rats, sorafenib caused severe cardiotoxicity with decreased left ventricular systolic pressure, elongated sarcomere, enlarged mitochondria and decreased ATP. This was associated with alternative splicing of hundreds of genes in the hearts, many of which were targets of a cardiac specific splicing factor, RBM20. Sorafenib inhibited RBM20 expression in both rat hearts and human cardiomyocytes. The splicing of RBM20's targets, SLC25A3 and FHOD3, was altered into fetal isoforms with decreased function. Upregulation of RBM20 during sorafenib treatment reversed the pathogenic splicing of SLC25A3 and FHOD3, and enhanced the phosphate transport into mitochondria by SLC25A3, ATP synthesis and cell survival.We envision this regulation may happen in many drug-induced cardiotoxicity, and represent a potential druggable pathway for mitigating sorafenib-induced cardiotoxicity.

Gcn5 determines the fate of Drosophila germline stem cells through degradation of Cyclin A.

The fluctuating CDK-CYCLIN complex plays a general role in cell-cycle control. Many types of stem cells use unique features of the cell cycle to facilitate asymmetric division. However, the manner in which these features are established remains poorly understood. The cell cycle of Drosophila female germline stem cells (GSCs) is characterized by short G1 and very long G2 phases, making it an excellent model for the study of cell cycle control in stem cell fate determination. Using a Drosophila female GSC model, we found Gcn5, the first discovered histone acetyltransferase, to maintain germline stem cells in Drosophila ovaries. Results showed that Gcn5 is dispensable for the transcriptional silencing of bam, but interacts with Cyclin A to facilitate proper turnover in GSCs. Results also showed that Gcn5 promotes Cyclin A ubiquitination, which is dependent on its acetylating activity. Finally, results showed that knockdown of Cyclin A rescued the GSC-loss phenotype caused by lack of Gcn5. Collectively, these findings support the conclusion that Gcn5 acts through acetylation to facilitate Cyclin A ubiquitination and proper turnover, thereby determining the fate of GSCs.-Liu, T., Wang, Q., Li, W., Mao, F., Yue, S., Liu, S., Liu, X., Xiao, S., Xia, L. Gcn5 determines the fate of Drosophila germline stem cells through degradation of Cyclin A.

[Identification of C(2)M interacting proteins by yeast two-hybrid screening].

The synaptonemal complex (SC) is a huge structure which assembles between the homologous chromosomes during meiotic prophase I. Drosophila germ cell-specific nucleoprotein C(2)M clustering at chromosomes can induce SC formation. To further study the molecular function and mechanism of C(2)M in meiosis, we constructed a bait vector for C(2)M and used the yeast two-hybrid system to identify C(2)M interacting proteins. Forty interacting proteins were obtained, including many DNA and histone binding proteins, ATP synthases and transcription factors. Gene silencing assays in Drosophila showed that two genes, wech and Psf1, may delay the disappearance of SC. These results indicate that Wech and Psf1 may form a complex with C(2)M to participate in the formation or stabilization of the SC complex.

Inonotus obliquus and its bioactive compounds alleviate non-alcoholic fatty liver disease via regulating FXR/SHP/SREBP-1c axis.

Non-alcoholic fatty liver disease (NAFLD) is currently the most common chronic liver disease worldwide. However, there is still lack of specific drugs for treating NAFLD in clinic. Inonotus obliquus (IO), a folk medicinal fungus, has long been used to prevent against metabolic syndrome related diseases, such as hypertension and diabetes, etc. However, the study of IO anti-NAFLD effect has been reported rarely. This study aimed to investigate whether IO has an inhibitory effect on NAFLD, identify the active compounds in IO and clarify the underlying mechanisms of its anti-NAFLD effects. The results of Oil Red O(ORO) and Hematoxylin-Eosin (HE) staining, lipid extraction and determination showed that IO and its extracts, including inotodiol (Ino), lanosterol (Lan) and trametenolic acid (TA), could remarkably ameliorate lipid accumulation in MCD diet-induced mouse livers or OA-induced LO2 hepatocytes. Moreover, qPCR analysis revealed that IO and its compounds significantly downregulated the mRNA levels of lipogenic genes, such as SREBP-1c, ACC1 and FASN, and upregulated the mRNA levels of FXR and SHP. We found that the administration of guggulsterone (GS), a FXR inhibitor, abolished the inhibitory effect of Ino on lipid deposition in OA-induced LO2 cells. In conclusion, IO and its compounds attenuate hepatic lipid accumulation in NAFLD by inhibiting liver lipogenesis. The anti-NAFLD effects of Ino, a bioactive compound in IO, are through regulating FXR/SHP/SREBP-1c pathway. Our results suggested that IO and its bioactive compound Ino may become promising drugs to treat NAFLD.

Antrodia cinnamomea and its compound dehydroeburicoic acid attenuate nonalcoholic fatty liver disease by upregulating ALDH2 activity.

ETHNOPHARMACOLOGICAL RELEVANCE: Nonalcoholic fatty liver disease (NAFLD) is a prevalent liver disease, but currently has no specific medication in clinic. Antrodia cinnamomea (AC) is a medicinal fungus and it has been shown that AC can inhibit high fat diet (HFD)-induced lipid deposition in mouse livers, but the effective monomer in AC and mechanism against NAFLD remain unclear. It has been reported that aldehyde dehydrogenase 2 (ALDH2) activation shows protective effects on NAFLD. Our previous study demonstrates that AC and its monomer dehydroeburicoic acid (DEA) can upregulate the ALDH2 activity on alcoholic fatty liver disease mouse model, but it is not clear whether the anti-NAFLD effects of AC and DEA are mediated by ALDH2. AIM TO STUDY: To elucidate the active compound in AC against NAFLD, study whether ALDH2 mediates the anti-NAFLD effects of AC and its effective monomer. MATERIALS AND METHODS: WT mice, ALDH2-/- mice and ALDH2-/- mice re-expressed ALDH2 by lentivirus were fed with a methionine-choline deficient (MCD) diet or high fat diet (HFD) to induce NAFLD, and AC at the different doses (200 and/or 500 mg/kg body weight per day) was administrated by gavage at the same time. Primary hepatocytes derived from WT and ALDH2-/-mice were stimulated by oleic acid (OA) to induce lipid deposition, and the cells were treated with AC or DEA in the meantime. Lentivirus-mediated ALDH2-KD or ALDH2-OE were used to knock down or overexpress ALDH2 expression in HepG2 cells, respectively. Finally, the effects of DEA against NAFLD as well as its effects on upregulating liver ALDH2 and removing the harmful aldehyde 4-hydroxynonenal (4-HNE) were studied in the MCD diet-induced NAFLD mouse model. RESULTS: In WT mice fed with a MCD diet or HFD, AC administration reduced hepatic lipid accumulation, upregulated ALDH2 activity in mouse livers, decreased 4-HNE contents both in mouse livers and serum, inhibited lipogenesis, inflammation and oxidative stress and promoted fatty acid ß-oxidation. These effects were abolished in ALDH2 KO mice but could be restored by re-expression of ALDH2 by lentivirus. In primary hepatocytes of WT mice, AC and DEA inhibited OA-induced lipid accumulation and triglyceride (TG) synthesis, promoting the ß-oxidation of fatty acid in the meantime. However, these effects were lost in primary hepatocytes of ALDH2 KO mice. Moreover, the expression level of ALDH2 significantly affected the inhibitory effects of AC and DEA on OA-induced lipid deposition in HepG2 cells. The effects of AC and DEA on suppressing lipid deposition, inhibiting mitochondrial ROS levels, reducing TG synthesis, and promoting ß-oxidation of fatty acid were all enhanced with the overexpression of ALDH2 and reduced with the knockdown of ALDH2 expression. DEA showed dose-dependent effects on inhibiting liver lipid deposition, elevating ALDH2 activity and reducing 4-HNE levels in the livers of MCD diet-induced NAFLD mice. CONCLUSION: DEA is the effective compound in AC against NAFLD. The related anti-NAFLD mechanisms of AC and DEA were through upregulating ALDH2 expression and activity, thus enhancing the elimination of 4-HNE in the livers, and sequentially alleviating oxidative stress and inflammation, promoting fatty acid ß-oxidation and decreasing lipogenesis.

A Review of Research Progress on Agathis dammara and its Application Prospects for Cardiovascular Diseases and Fatty Liver Disease.

Cardiovascular diseases and fatty liver disease have become the leading causes of death in modern society. However, the currently existing drugs do not solve all issues related to these diseases; thus, it is expected that more potential drugs for clinical use will be developed. Undeniably, natural products have attracted increasing attention. It is of great significance to identify effective active monomer components for drug discovery and disease prevention. As a pure natural product, Agathis dammara (AD) has antioxidant, hypolipidemic, hypoglycemic, antitumor, and anti-inflammatory activities. However, at present, there are few reports regarding the effects of AD on chronic inflammatory cardiovascular diseases, such as aneurysm, atherosclerosis, myocardial ischemia-reperfusion injury, and cardiac hypertrophy and liver diseases such as fatty liver disease. AD and products derived from it have a very broad application prospect for cardiovascular diseases and fatty liver disease.

Protective Effects of Antrodia cinnamomea and Its Constituent Compound Dehydroeburicoic Acid 32 Against Alcoholic Fatty Liver Disease.

BACKGROUND: Alcoholic fatty liver disease (AFLD), a leading chronic hepatic disease, affects an increasing number of people, and no effective drugs for the treatment of AFLD are available. Antrodia cinnamomea (AC) can inhibit AFLD, but its mechanisms and the effective compound in AC are unknown. OBJECTIVE: We aimed to explore the anti-AFLD mechanism of AC and the active compound within AC. METHODS: Wild-type (WT) C57BL/6J mice underwent 4 weeks of daily ethanol (EtOH) feeding to induce AFLD. AC or dehydroeburicoic acid 32 (DEA32), a compound in AC, was given to the mice. Parallel experiments to assess the effect of AC were conducted in aldehyde dehydrogenase 2 (ALDH2)-knockout (KO) mice. Primary mouse hepatocytes were incubated with ethanol and Alda- 1 (an ALDH2 agonist), AC or DEA32. RESULTS: In WT mice with AFLD, AC reduced lipid deposition, increased the expression and activity of ALDH2, reduced the acetaldehyde content, and downregulated the expression of lipogenic and inflammatory genes in the liver. These effects of AC disappeared in ALDH2 KO mice. DEA32 was identified as an active compound in AC, as its effects on EtOH-treated WT hepatocytes were similar to those of AC, which were comparable to the effects of Alda-1. These effects of DEA32 disappeared in EtOH-treated ALDH2 KO hepatocytes. Furthermore, in WT mice with AFLD, DEA32 reduced lipid deposition, increased the activity of ALDH2, and reduced the accumulation of acetaldehyde in the liver. DEA32 also downregulated the mRNA expression of genes related to lipogenesis and inflammation. CONCLUSION: AC and its constituent compound DEA32 inhibit AFLD by upregulating ALDH2 activity, accelerating acetaldehyde metabolism, and suppressing lipogenesis and inflammation in the liver.

Naringenin attenuates non-alcoholic fatty liver disease by down-regulating the NLRP3/NF-κB pathway in mice.

BACKGROUND AND PURPOSE: Naringenin, a flavonoid compound with strong anti-inflammatory activity, attenuated non-alcoholic fatty liver disease (NAFLD) induced by a methionine-choline deficient (MCD) diet in mice. However, the mechanisms underlying this suppression of inflammation and NAFLD remain unknown. EXPERIMENTAL APPROACH: WT and NLRP3-/- mice were fed with MCD diet for 7 days to induce NAFLD and were given naringenin by gavage at the same time. in vitro experiments used HepG2 cells, primary hepatocytes, and Kupffer cells (KCs) stimulated by LPS or LPS plus oleic acid (OA). KEY RESULTS: Treating WT mice with naringenin (100 mg·kg-1 ·day-1 ) attenuated hepatic lipid accumulation and inflammation in the livers of mice given the MCD diet. NLRP3-/- mice showed less hepatic lipid accumulation than WT mice, but naringenin did not ameliorate hepatic lipid accumulation further in NLRP3-/- mice. Treating the HepG2 cells with naringenin or NLRP3 inhibitor MCC950 reduced lipid accumulation. Naringenin inhibited activation of the NLRP3/NF-κB pathway stimulated by OA together with LPS. In KCs isolated from WT mice, naringenin inhibited NLRP3 expression. Naringenin also inhibited lipid deposition, NLRP3 and IL-1ß expression in WT hepatocytes but was not effective in NLRP3-/- hepatocytes. After re-expressing NLRP3 in NLRP3-/- hepatocytes by adenovirus, the anti-lipid deposition effect of naringenin was restored. CONCLUSION AND IMPLICATIONS: Naringenin prevented NAFLD via down-regulating the NLRP3/NF-κB signalling pathway both in KCs and in hepatocytes, thus attenuating inflammation in the mice livers.