Project description:Acute myeloid leukemia (AML) is a hematologic malignancy with a poor prognosis. We discovered that BMAL1 is a ferroptosis suppressor. Furthermore, it was also found to be overexpressed in AML patients, affecting the cell cycle and promoting tumor cell growth and progression. In this study, we further validated the association of BMAL1 with the progression and survival outcomes of AML. Lipidomic revealed that the levels of ceramide increased in AML cells following the depletion of BMAL1. Ceramide facilitated ferroptosis in AML cells. ASAH2 played a key role in this process. BMAL1 could not directly regulate ASAH2 but instead through IKZF2. Elevated levels of ceramide promoted the degradation of the ferroptosis protection molecule GPX4, ultimately promoting ferroptosis. Furthermore, ceramide treatment has been demonstrated to enhance the responsiveness of AML cells to sorafenib. In summary, this study elucidates that BMAL1 depletion remodels ceramide metabolism to regulate the sensitivity of AML cells to ferroptosis and targeted drug sorafenib.
Project description:Ferroptosis is an iron-dependent form of cell death driven by biochemical and metabolic alterations resulting in oxidation within the lipid compartment. Calcium is a potent signaling molecule ascribed to diverse cellular processes including migration, neurotransmitter function, and cell death. Here we elucidate a crucial link between calcium homeostasis and ferroptotic cell death through the identification of the tetraspanin MS4A15. Ectopic MS4A15 expression specifically protects against ferroptosis by depleting endoplasmic reticulum stores. In an unexpected connection, prolonged calcium dysregulation stimulates fundamental remodeling to ferroptosis-resistant monounsaturated and plasmalogen lipid species. Application of this discovery revealed that augmenting luminal calcium sensitizes cancer cell lines previously refractory to ferroptosis. This finding provides a unique mechanistic basis for ferroptosis sensitivity and resolves a long-standing query into the role of calcium in oxidative cell death. Manipulating calcium homeostasis offers an unprecedented strategy for overcoming therapy resistance in cancer.
Project description:Ferroptosis is an iron-dependent regulated cell death caused by the accumulation of lipid peroxidation for the uncontrolled metabolism. Serum, as the major medium for the cultured cells, resembles the contents of the extracellular fluid in vivo and provides biomolecules for cellular metabolism. The efficiency of ferroptosis induction is influenced by several factors including the extracellular environment. However, the effect of serum on ferroptosis remains largely unclear. We found that cells cultured in different serums have varying efficiencies in ferroptosis induction. By purifying and identifying active serum components, we discovered that serum protein apolipoprotein H (APOH) play essential role in inhibiting ferroptosis. Moreover, APOH activates the phosphoinositide 3-kinase (PI3K)/AKT-Sterol regulatory element-binding proteins (SREBPs) pathway. SREBPs upregulate the stearoyl-CoA desaturase (SCD) increasing cellular monounsaturated fatty acid-containing phospholipids (MUFA-PLs), leading to ferroptosis inhibition. Our findings indicate that APOH, as an extracellular protein, plays an important role in cellular lipid metabolism and inhibition of ferroptosis, thus may having therapeutic applications in cancer treatment and ferroptosis-related diseases.
Project description:Ferroptosis is a form of cell death driven by iron-dependent lipid peroxidation, with specific lipid species playing key roles in modulating susceptibility. Among these, ether lipids have shown conflicting effects, being linked to both protection and sensitization. Here, we dissect the relationship between lipid structure and ferroptosis sensitivity and explain how ether lipids exert context-dependent effects. Ether lipids can promote ferroptosis through a metabolic bias towards the accumulation of polyunsaturated acyl chains and ethanolamine head groups, whereas this pro-ferroptotic tendency is counterbalanced by the anti-ferroptotic vinyl ether moiety introduced by plasmanylethanolamine desaturase 1. We show that this protective effect is critical for preventing ferroptosis in hiPSC-derived neurons, which accumulate otherwise pro-ferroptotic ether lipids during differentiation. This effect is not solely due to its antioxidant properties but also stems from the reprogramming of mitochondrial respiration. The lack of vinyl ether bonds leads to multiple mitochondrial defects, including increased mitochondrial reactive oxygen species (ROS), lower membrane potential, and abnormal cristae structures. These findings indicate that vinyl ether bonds in ether lipids offer dual ferroptosis resistance by scavenging ROS and minimizing its production at the mitochondrial level. The disruption of this system in Caenorhabditis elegans leads to iron-induced death and impaired motility. Thus, our study reveals ether lipid structural remodeling as a key regulator of ferroptosis sensitivity in neurons.
Project description:Common genetic variants in a 58-kilobase (kb) region of chromosome 9p21, near the CDKN2A/B cell proliferation inhibitor genes, are strongly associated with coronary artery disease (CAD). We previously reported a congenic mouse model harboring an atherosclerosis susceptibility locus in a region of homology with the human 9p21 locus. We now report markedly decreased Cdkn2a (cyclin-dependent kinase inhibitor 2a) mRNA expression in macrophages and increased circulating levels of Ly6Chigh inflammatory monocytes in congenic mice compared to controls. A bone marrow (BM) transplantation study revealed that BM-derived cells from Cdkn2a+/- mice are capable of conferring accelerated atherosclerosis, increased inflammatory monocyte subsets and monocyte proliferation in the Ldlr-/- mouse model. These findings provide a mechanistic link between decreased expression of Cdkn2a transcripts, increased monocyte proliferation, and accelerated atherosclerosis. Aorta and macrophages from ten C57BL/6.MOLFc4(51Mb)-Ldlr-/- mice and their control C57BL/6-Ldlr-/- were obtained, RNA purified and hybridized to GPL9734 Affimetrix microarrays.
Project description:Ferroptosis is a form of regulated necrotic cell death controlled by glutathione peroxidase 4 (GPX4). At present, mechanisms that could predict sensitivity and/or resistance and that may be exploited to modulate this form of cell death are needed. We applied two independent approaches, a genome-wide CRISPR-based genetic screen and microarray analysis of ferroptosis-resistant cell lines to uncover acyl-CoA synthetase long-chain family member 4 (Acsl4) as an essential component for ferroptosis execution.
Project description:Common genetic variants in a 58-kilobase (kb) region of chromosome 9p21, near the CDKN2A/B cell proliferation inhibitor genes, are strongly associated with coronary artery disease (CAD). We previously reported a congenic mouse model harboring an atherosclerosis susceptibility locus in a region of homology with the human 9p21 locus. We now report markedly decreased Cdkn2a (cyclin-dependent kinase inhibitor 2a) mRNA expression in macrophages and increased circulating levels of Ly6Chigh inflammatory monocytes in congenic mice compared to controls. A bone marrow (BM) transplantation study revealed that BM-derived cells from Cdkn2a+/- mice are capable of conferring accelerated atherosclerosis, increased inflammatory monocyte subsets and monocyte proliferation in the Ldlr-/- mouse model. These findings provide a mechanistic link between decreased expression of Cdkn2a transcripts, increased monocyte proliferation, and accelerated atherosclerosis.