Acta Biochimica et Biophysica Sinica•2025•DOI: 10.3724/abbs.2025014
Ferroptosis is a novel form of regulated cell death characterized by the iron-dependent accumulation of lipid peroxides. Recent research has suggested that ferroptosis in osteoblasts contributes to steroid-induced osteonecrosis of the femoral head (SONFH). However, the relationship between ferroptosis and SONFH remains unclear. In this study, in vitro experiments show that dexamethasone (Dex) treatment reduces the expressions of key ferroptosis regulators, SLC7A11 and GPX4, in MC3T3-E1 cells. This reduction leads to a decrease in intracellular glutathione (GSH) levels, accompanied by elevated levels of total iron, malondialdehyde (MDA), and reactive oxygen species (ROS). Importantly, the ferroptosis inhibitor ferrostatin-1 (Fer-1) effectively reverses Dex-induced ferroptosis in MC3T3-E1 cells. Furthermore, RNA-seq analysis reveals that the long noncoding RNA (lncRNA) XR_877193.1 is significantly upregulated in Dex-treated MC3T3-E1 cells. Functional studies demonstrate that the knockdown of lncRNA XR_877193.1 promotes osteogenic differentiation by inhibiting Dex-induced ferroptosis in MC3T3-E1 cells, whereas its overexpression exacerbates cell death via ferroptosis. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis reveals that the differentially expressed lncRNA XR_877193.1 is enriched in ferroptosis-related pathways, including the PI3K/AKT signaling pathway. Moreover, PI3K/AKT inhibitors reverse ferroptosis in MC3T3-E1 cells inhibited by lncRNA XR_877193.1 knockdown. Collectively, our findings indicate that lncRNA XR_877193.1 knockdown exerts anti-ferroptosis effects by stimulating the PI3K/AKT signaling pathway, suggesting a promising therapeutic strategy for attenuating SONFH.
Acta Biochimica et Biophysica Sinica•2025•DOI: 10.3724/abbs.2024096
Autophagy is a cellular mechanism for self-renewal that involves the breakdown of cytoplasmic proteins or organelles within lysosomes. Although preeclampsia (PE) exhibits several characteristics that could imply disrupted autophagy, there is limited evidence supporting the notion that impaired placental autophagy directly causes PE, as indicated by differential expression profiling of whole placental tissue. In this study, we aim to explore the significance of autophagy in maintaining pregnancy and its association with PE. First, the RNA-seq results show that 218 genes are differentially expressed in placentas from preeclamptic pregnancies. Notably, KEGG pathway analysis reveals significant enrichment of genes related to autophagy-related signaling pathways, including the PI3K-Akt signaling pathway, the AMPK signaling pathway, and the mTOR signaling pathway. Additionally, our findings indicate an increase in autophagy in placentas from pregnancies complicated by preeclampsia as well as in trophoblasts subjected to hypoxic conditions. Next, we examine the impact of 3-methyladenine (3-MA), a targeted inhibitor of autophagy, on the progression of PE. The administration of 3-MA profoundly alleviates the severity of PE-like symptoms in rats subjected to reduced uterine perfusion pressure (RUPP). The findings from our study suggest that inhibiting autophagy may serve as a promising approach for adjuvant chemotherapy for PE.
Acta Biochimica et Biophysica Sinica•2025•DOI: 10.3724/abbs.2025096
Ferroptosis, a novel form of regulated necrosis, has drawn the attention of the scientific community. Nevertheless, few studies have focused on the impact of ferroptosis on MC3T3-E1 cells in the context of steroid-induced osteonecrosis of the femoral head (SONFH). In this study, we explore the relationship between the degree of ferroptosis induced by dexamethasone (Dex) and the expression of silent information regulatory protein 1 (Sirt1). The results indicate that the ferroptosis level induced by Dex is mediated by the downregulation of Sirt1. Overexpression of Sirt1 increases the levels of the ferroptosis-related proteins SLC7A11 and GPX4 in MC3T3-E1 cells following Dex exposure. Moreover, the effect of Dex on Sirt1 expression is regulated by hypermethylation of the Sirt1 promoter, which is catalyzed by DNA methyltransferase 3a (DNMT3a). In summary, this study reveals that Dex can trigger ferroptosis by promoting DNMT3a-mediated DNA methylation and downregulating Sirt1 expression. Our findings provide an additional new mechanism for Dex-induced ferroptosis in MC3T3-E1 cells.
Acta Biochimica et Biophysica Sinica•2025•DOI: 10.3724/abbs.2025096
Steroid-induced osteonecrosis of the femoral head (SONFH) is a progressive bone disorder driven by prolonged glucocorticoid exposure, with limited therapeutic options. Ferroptosis, a regulated form of necrosis, has emerged as a potential contributor to SONFH pathogenesis, yet its mechanistic link to osteoblast dysfunction remains poorly defined. This study investigates the relationship between dexamethasone (Dex)-induced ferroptosis and silent information regulator 1 (Sirt1) in MC3T3-E1 osteoblastic cells. Dex treatment downregulated Sirt1 expression and increased ferroptosis markers, while Sirt1 overexpression elevated the ferroptosis-related proteins SLC7A11 and GPX4 following Dex exposure. Mechanistically, Dex promoted hypermethylation of the Sirt1 promoter via DNA methyltransferase 3a (DNMT3a), leading to Sirt1 suppression. These findings establish a novel epigenetic axis—DNMT3a-mediated Sirt1 promoter hypermethylation—that drives Dex-induced ferroptosis in osteoblasts. The study was conducted exclusively in vitro, and the pathophysiological relevance requires validation in animal models. Nevertheless, this work provides a foundation for understanding the epigenetic regulation of osteoblast ferroptosis and suggests potential therapeutic avenues for preventing SONFH.
Acta Biochimica et Biophysica Sinica•2025•DOI: 10.3724/abbs.2025021
Homocysteine (Hcy) is an independent risk factor for atherosclerosis, and defective macrophage autophagy accelerates plaque formation. Pyruvate dehydrogenase (PDH), a key component of the PDH complex, links energy metabolism to autophagy, but its role in Hcy-induced atherosclerosis remains undefined. Proteomic profiling of Hcy-treated macrophages identified 748 upregulated and 760 downregulated proteins, with KEGG enrichment in amino acid biosynthesis, carbon metabolism, and glycolysis/gluconeogenesis. In ApoE–/– mice, Hcy treatment markedly reduced PDH expression and activity, leading to impaired autophagy. PDH activation restored autophagy by promoting assembly of the ULK1-FIP200-Atg13 complex via modulation of AMPK/mTOR signaling. These findings suggest that PDH activation may serve as a therapeutic strategy for Hcy-induced atherosclerosis.