Zhanfang Kang

The liver is a central organ controlling lipid and cholesterol metabolism and plays a key role in regulating lipoprotein profiles and cardiovascular disease risk. Males and females show clear differences in cholesterol handling and susceptibility to atherosclerosis, but the molecular basis for these sex-specific effects remains incompletely understood. Here we show that the X-linked histone demethylase 6 A (KDM6A) is essential for maintaining healthy cholesterol metabolism in the liver. Reducing KDM6A levels in human liver cells from females but not males disrupts gene programs involved in lipoprotein regulation linked to cardiovascular disorders. Consistently, female mice lacking KDM6A specifically in hepatocytes develops pro-atherogenic blood lipoprotein profiles and increased atherosclerosis under genetic and dietary stress, whereas males are largely unaffected. Mechanistically, KDM6A cooperates with Hepatocyte Nuclear Factor 4 Alpha (HNF4A) to promote chromatin activation and enable CREBH (encoded by CREB3L3)-dependent transcription of lipid metabolic genes. These findings identify KDM6A as a sex-linked regulator of hepatic cholesterol metabolism.

Castration-resistant prostate cancer (CRPC) remains a significant therapeutic challenge with limited effective treatment options. We identified retinoid X receptor γ (RXRγ) as a critical regulator of CRPC cell proliferation, highlighting it as a previously unrecognized and tractable target for therapeutic intervention. However, no RXRγ-selective modulators have been reported. Herein, we utilized the PROTAC approach to develop WCF-598 as a potent RXRγ degrader, which exhibits preferential degradation of RXRγ over RXRα and RXRβ isoforms. WCF-598 promoted efficient RXRγ degradation through the ubiquitin-proteasome system, leading to robust antiproliferative activity in CRPC models. In vivo, WCF-598 induced significant tumor regression in 22Rv1 xenograft-bearing mice without observable toxicity. Notably, WCF-598 also exhibited a secondary activity by degrading androgen receptor splice variant 7 (AR-V7), a clinically relevant driver of therapy resistance in CRPC. These results establish WCF-598 as a specific chemical probe for investigating the function of RXRγ in CRPC and potentially other RXRγ-related diseases.

Metformin is an approved anti diabetes drug and has potential cardioprotective effects. It is unclear whether the antioxidant effect plays a role in this process. The reactive carbonyl compound 4-HNE, produced during lipid peroxidation, is highly reactive and has been implicated in the pathology of heart diseases, such as diabetic cardiomyopathy, although the exact mechanisms remain unclear. In this study, we identified 4-HNE protein adducts by mass spectrometry in cardiomyocytes, and investigated the mechanism of 4-HNE induced cell death and the protective effect of metformin in cardiomyocytes and diabetic cardiomyopathy models. H9C2 cardiomyocytes were cultured and treated with different concentrations of 4-HNE for in vitro experiments. A mouse model of diabetic cardiomyopathy was established by HFD feeding and STZ injection, and treated with metformin. 4-HNE covalently binds to the key protein VCP to mediate cardiomyocyte death. 4-HNE inhibits the ATPase activity of VCP and disrupted its downstream signaling pathway, including increased ubiquitinated protein levels, unfolded protein response, and ultimately leads to cardiomyocyte death. In contrast, overexpression of VCP in H9C2 cardiomyocytes protected 4-HNE induced protein ubiquitination and cell death. Mass spectrometry analysis revealed that 4-HNE binds to VCP at residues K336. In addition, metformin reduced the ubiquitination and death of cardiomyocytes induced by 4-HNE through activation of Nrf2-GSTP1 pathway. In HFD-STZ diabetic cardiomyopathy mice, metformin treatment significantly improved cardiac function, reduced cardiac fibrosis and apoptosis, accompanied by a decrease in the levels of 4-HNE adducts and protein ubiquitination. Our results show that 4-HNE directly binds to VCP and disrupts its signaling pathway, induces ubiquitination accumulation, which ultimately leads to cardiomyocyte death, providing a new mechanism for the cardiac injury of 4-HNE. Meanwhile, metformin effectively alleviates 4-HNE induced ubiquitination and cell death in cardiomyocytes and diabetic cardiomyopathy models, and improves cardiac function, demonstrating potential therapeutic effects.

The liver is a central organ in the maintenance of lipid metabolism. It coordinates cholesterol uptake, biosynthesis, excretion and clearance through an intricated transcription network defined in the epigenetic level by transcription factors and coregulators. Those networks differ between males and females, resulting in marked sex differences in lipoprotein patterns and risk of developing atherosclerosis. How sex chromosome-linked epigenetic modulators contribute to such sex-specific metabolism remains unclarified. Here, we have demonstrated that the X- linked histone demethylase 6A (KDM6A) is a crucial coregulator involved in liver cholesterol regulation. KDM6A knockdown in human liver cells induces transcriptional changes annotated to lipoprotein and cholesterol metabolic pathways linked with cardiovascular disorders. Consistently, hepatocyte specific KDM6A knockout (LKO) female, but not male, mice display substantial atherogenic circulating lipoprotein profiles and are prone to developing atherosclerosis upon genetic and dietary challenges. Mechanistically, KDM6A is recruited to chromatin by Hepatic Nuclear Factor 4 Alpha (HNF4A). This creates an active epigenetic microenvironment essential for the binding of cAMP-responsive element-binding protein H (CREBH, encoded by CREB3L3), which subsequently activates the transcription of lipoprotein and cholesterol metabolic genes in hepatocytes. Therefore, our study uncovers a novel mechanistic link of KDM6A with atherosclerosis using both human cell and mouse models. Because KDM6A is an X-inactivation ‘escapee’ with higher expression in female than male hepatocytes, it may contribute to the sex dimorphism of cholesterol metabolism and cardiovascular risk.

Background: Periplocae cortex is a well-known Traditional Chinese Medicine with abundant effects, including the treatment of chronic congestive heart failure (CHF). However, the principal components and mechanisms have not been fully elucidated. This study aims to analyze the active ingredients and potential mechanisms of the periplocae cortex in CHF treatment. Methods: TCMSP, GeneCards, and Comparative Toxicogenomics databases were used to mine the active ingredients and potential targets of the periplocae cortex. Cytoscape 3.9.1 software was employed to construct the “periplocae cortex-active ingredients-potential targets” and protein–protein interaction network. The DAVID 6.8 database was used for Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the predicted targets. The protective effects of β-sitosterol (BSS) were detected in doxorubicin (Dox)-induced H9c2 cells using MTT assay, while the regulatory pathways of BSS were examined using various assays, including real-time quantitative PCR and Western blot. The cardiac troponin I (cTn-I) concentration was also measured. Results: A total of 13 active ingredients were identified, and 33 targets of CHF were predicted. Network analysis highlighted BSS as the key active ingredient, interacting with 29 targets. GO and KEGG analyses indicated significant involvement of these targets in calcium and apoptosis signaling pathways. Experimental findings demonstrated that BSS enhanced cell viability, reduced intracellular calcium ion concentration, and inhibited caspase 3 activity in Dox-induced H9c2 cells. BSS significantly altered the expression of CHRM1, CASP3, and CASP9 genes ( P < .05), and increased CHRM2 expression. Additionally, BSS significantly increased cTn-I concentration. Notably, suppression of calcium and apoptosis signaling pathways partially mitigated BSS's effects on cell viability and cTn-I concentration. Conclusion: Through network pharmacology and experimental verification, establishes BSS as a key active ingredient in the periplocae cortex for CHF treatment. BSS appears to modulate calcium and apoptosis signaling pathways, thereby exerting therapeutic effects in the treatment of CHF.

The AMP-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) pathway performs a crucial role in energy metabolism and mitochondrial network. Our previous study found that DT-010, a novel danshensu (DSS) and tetramethylpyrazine (TMP) conjugate, had significant cardioprotective properties in vitro and in vivo. We also reported that ERp57 served as a major target of DSS using the chemical proteomics approach. In this article, we focus on exploring the interrelationship between the regulation of the AMPK/PGC-1α pathway and promoting ERp57 expression induced by DT-010 in tert-butylhydroperoxide- (t-BHP-) induced H9c2 cell injury. The results showed that DT-010 activated the AMPK/PGC-1α pathway and increased ERp57 protein expression. Importantly, the above phenomenon as well as the mitochondrial function can be partially reversed by siRNA-mediated ERp57 suppression. Meanwhile, silencing AMPK significantly inhibited the ERp57 expression induced by DT-010. In addition, molecular docking and kinase assay in vitro revealed that DT-010 had no direct regulation effects on AMPK activity. Taken together, DT-010 exerted cardioprotective effects by regulating the crosstalk of AMPK/PGC-1α pathway and ERp57, representing a potential therapeutic agent for ischemic heart disease.

The widely used lipid-lowering drug niacin was reported to increase blood glucose in diabetes. How does niacin regulate β Cell function in diabetic patients remains unclear. This study aimed to investigate the effect of niacin on β cell lipotoxicity in vitro and in vivo. Niacin treatment sensitized the palmitate-induced cytotoxicity and apoptosis in INS-1 cells. In addition, palmitate significantly increased the niacin receptor GPR109A and PPARγ2 levels, which could be further boosted by niacin co-treatment, creating a vicious cycle. In contrast, knocking down of GPR109A could reverse both PPARγ2 expression and niacin toxicity in the INS-1 cells. Interestingly, we found that GLP-1 receptor agonist exendin-4 showed similar inhibitive effects on the GPR109A/PPARγ2 axis and was able to reverse niacin induced lipotoxicity in INS-1 cells. In diet-induced obesity (DIO) mouse model, niacin treatment resulted in elevated blood glucose, impaired glucose tolerance and insulin secretion, accompanied by the change of islets morphology and the decrease of β cell mass. The combination of niacin and DPP-4 inhibitor sitagliptin can improve glucose tolerance, insulin secretion and islet morphology and β cell mass, even better than sitagliptin alone. Our results show that niacin increased β cell lipotoxicity partially through upregulation of GPR109A and PPARγ2, which can be alleviated by incretin drugs. We provide a new mechanism of niacin toxicity, and suggest that the combination of niacin and incretin may have better blood glucose and lipid control effect in clinical practice.

Temozolomide (TMZ) can cross the blood‐brain barrier (BBB) and deliver methyl groups to the purine (guanine) bases of DNA, leading to mispairing during DNA replication and subsequent cell death. However, increased expression of the repair enzyme methyl guanine methyltransferase (MGMT), which removes methyl groups from purine bases, counteracts methylation by TMZ. We evaluated the anticancer potential of thymoquinone (TQ), a hydrophobic flavonoid that inhibits resistance and induces apoptosis in various cancer cells, both in vitro and in vivo. In vitro experiments showed that compared with the Hs683 and M059J cell lines, U251 cells were more sensitive to TMZ. Compared to U251 cells, U251R cells, a TMZ drug‐resistant strain established in this study, are characterized by increased expression of phosphorylated extracellular signal‐regulated kinase (p‐ERK) and MGMT. TQ treatments induced apoptosis in all cell lines. The p38 mitogen‐activated protein kinase signal pathway was mainly activated in U251 and U251R cells; however, p‐ERK and MGMT upregulation could not suppress TQ effects. Furthermore, si‐p38 pretreatment of U251R cells in TQ treatments inhibited cell apoptosis. We speculate that TQ contributed to the phosphorylation and activation of p38, but not of ERK‐induced apoptosis (irrespective of TMZ resistance). In vivo, U251R‐derived tumors subcutaneously inoculated in nude mice exhibited significant tumor volume reduction after TQ or TQ + TMZ cotreatments. High‐performance liquid chromatography assay confirmed the presence of TQ in murine brain tissues. Our findings demonstrate that TQ can effectively cross the BBB and function alone or in combination with TMZ to treat glioblastoma.