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Journal of Experimental & Clinical... May 2024Sorafenib is a standard first-line treatment for advanced hepatocellular carcinoma (HCC), yet its effectiveness is often constrained. Emerging studies reveal that...
BACKGROUND
Sorafenib is a standard first-line treatment for advanced hepatocellular carcinoma (HCC), yet its effectiveness is often constrained. Emerging studies reveal that sorafenib triggers ferroptosis, an iron-dependent regulated cell death (RCD) mechanism characterized by lipid peroxidation. Our findings isolate the principal target responsible for ferroptosis in HCC cells and outline an approach to potentially augment sorafenib's therapeutic impact on HCC.
METHODS
We investigated the gene expression alterations following sgRNA-mediated knockdown induced by erastin and sorafenib in HCC cells using CRISPR screening-based bioinformatics analysis. Gene set enrichment analysis (GSEA) and the "GDCRNATools" package facilitated the correlation studies. We employed tissue microarrays and cDNA microarrays for validation. Ubiquitination assay, Chromatin immunoprecipitation (ChIP) assay, RNA immunoprecipitation (RIP) assay, and dual-luciferase reporter assay were utilized to delineate the specific mechanisms underlying ferroptosis in HCC cells.
RESULTS
Our study has revealed that pleiomorphic adenoma gene 1 (PLAG1), a gene implicated in pleomorphic adenoma, confers resistance to ferroptosis in HCC cells treated with sorafenib. Sorafenib leads to the opposite trend of protein and mRNA levels of PLAG1, which is not caused by affecting the stability or ubiquitination of PLAG1 protein, but by the regulation of PLAG1 at the transcriptional level by its upstream competitive endogenous long non-coding RNA (lncRNA) plasmacytoma variant translocation 1 (PVT1). Data from 139 HCC patients showed a significant positive correlation between PLAG1 and GPX4 levels in tumor samples, and PLAG1 is instrumental in redox homeostasis by driving the expression of glutathione peroxidase 4 (GPX4), the enzyme that reduces lipid peroxides (LPOs), which further leads to ferroptosis inhibition.
CONCLUSIONS
Ferroptosis is a promising target for cancer therapy, especially for patients resistant to standard chemotherapy or immunotherapy. Our findings indicate that PLAG1 holds therapeutic promise and may enhance the efficacy of sorafenib in treating HCC.
Topics: Humans; Sorafenib; Ferroptosis; Carcinoma, Hepatocellular; Liver Neoplasms; Phospholipid Hydroperoxide Glutathione Peroxidase; DNA-Binding Proteins; MicroRNAs; Mice; Animals; Cell Line, Tumor; Gene Expression Regulation, Neoplastic; Male
PubMed: 38745179
DOI: 10.1186/s13046-024-03061-4 -
American Journal of Human Genetics Jun 2024Anoctamins are a family of Ca-activated proteins that may act as ion channels and/or phospholipid scramblases with limited understanding of function and disease...
Anoctamins are a family of Ca-activated proteins that may act as ion channels and/or phospholipid scramblases with limited understanding of function and disease association. Here, we identified five de novo and two inherited missense variants in ANO4 (alias TMEM16D) as a cause of fever-sensitive developmental and epileptic or epileptic encephalopathy (DEE/EE) and generalized epilepsy with febrile seizures plus (GEFS+) or temporal lobe epilepsy. In silico modeling of the ANO4 structure predicted that all identified variants lead to destabilization of the ANO4 structure. Four variants are localized close to the Ca binding sites of ANO4, suggesting impaired protein function. Variant mapping to the protein topology suggests a preliminary genotype-phenotype correlation. Moreover, the observation of a heterozygous ANO4 deletion in a healthy individual suggests a dysfunctional protein as disease mechanism rather than haploinsufficiency. To test this hypothesis, we examined mutant ANO4 functional properties in a heterologous expression system by patch-clamp recordings, immunocytochemistry, and surface expression of annexin A5 as a measure of phosphatidylserine scramblase activity. All ANO4 variants showed severe loss of ion channel function and DEE/EE associated variants presented mild loss of surface expression due to impaired plasma membrane trafficking. Increased levels of Ca-independent annexin A5 at the cell surface suggested an increased apoptosis rate in DEE-mutant expressing cells, but no changes in Ca-dependent scramblase activity were observed. Co-transfection with ANO4 wild-type suggested a dominant-negative effect. In summary, we expand the genetic base for both encephalopathic sporadic and inherited fever-sensitive epilepsies and link germline variants in ANO4 to a hereditary disease.
Topics: Humans; Anoctamins; Mutation, Missense; Male; Female; Epilepsy; Child; Phospholipid Transfer Proteins; Genetic Association Studies; Pedigree; Calcium; Genes, Dominant; Child, Preschool; HEK293 Cells; Adolescent
PubMed: 38744284
DOI: 10.1016/j.ajhg.2024.04.014 -
Journal of Pharmaceutical Health Care... May 2024Coronary heart disease, also known as ischemic heart disease, is induced by atherosclerosis, which is initiated by subendothelial retention of lipoproteins. Plasma... (Review)
Review
Coronary heart disease, also known as ischemic heart disease, is induced by atherosclerosis, which is initiated by subendothelial retention of lipoproteins. Plasma lipoproteins, including high density lipoprotein, low density lipoprotein (LDL), very low density lipoprotein, and chylomicron, are composed of a surface monolayer containing phospholipids and cholesterol and a hydrophobic core containing triglycerides and cholesteryl esters. Phospholipids play a crucial role in the binding of apolipoproteins and enzymes to lipoprotein surfaces, thereby regulating lipoprotein metabolism. High LDL-cholesterol is a well-known risk factor for coronary heart disease, and statins reduce the risk of coronary heart disease by lowering LDL-cholesterol levels. In contrast, the relationships of phospholipids in plasma lipoproteins with coronary heart disease have not yet been established. To further clarify the physiological and pathological roles of phospholipids, we have developed the simple high-throughput assays for quantifying all major phospholipid classes, namely phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidic acid, phosphatidylinositol, phosphatidylglycerol + cardiolipin, and sphingomyelin, using combinations of specific enzymes and a fluorogenic probe. These enzymatic fluorometric assays will be helpful in elucidating the associations between phospholipid classes in plasma lipoproteins and coronary heart disease and in identifying phospholipid biomarkers. This review describes recent progress in the identification of phospholipid biomarkers of coronary heart disease.
PubMed: 38734675
DOI: 10.1186/s40780-024-00344-y -
Virulence Dec 2024() is the causative agent of Q fever, a zoonotic disease. Intracellular replication of requires the maturation of a phagolysosome-like compartment known as the...
() is the causative agent of Q fever, a zoonotic disease. Intracellular replication of requires the maturation of a phagolysosome-like compartment known as the replication permissive -containing vacuole (CCV). Effector proteins secreted by the Dot/Icm secretion system are indispensable for maturation of a single large CCV by facilitating the fusion of promiscuous vesicles. However, the mechanisms of CCV maintenance and evasion of host cell clearance remain to be defined. Here, we show that secreted vacuolar protein E (CvpE) contributes to CCV biogenesis by inducing lysosome-like vacuole (LLV) enlargement. LLV fission by tubulation and autolysosome degradation is impaired in CvpE-expressing cells. Subsequently, we found that CvpE suppresses lysosomal Ca channel transient receptor potential channel mucolipin 1 (TRPML1) activity in an indirect manner, in which CvpE binds phosphatidylinositol 3-phosphate [PI(3)P] and perturbs PIKfyve activity in lysosomes. Finally, the agonist of TRPML1, ML-SA5, inhibits CCV biogenesis and replication. These results provide insight into the mechanisms of CCV maintenance by CvpE and suggest that the agonist of TRPML1 can be a novel potential treatment that does not rely on antibiotics for Q fever by enhancing Coxiella-containing vacuoles (CCVs) fission.
Topics: Animals; Humans; Bacterial Proteins; Coxiella burnetii; HeLa Cells; Host-Pathogen Interactions; Lysosomes; Phosphatidylinositol 3-Kinases; Phosphatidylinositol Phosphates; Q Fever; Transient Receptor Potential Channels; Vacuoles
PubMed: 38725096
DOI: 10.1080/21505594.2024.2350893 -
STAT3 activation of SCAP-SREBP-1 signaling upregulates fatty acid synthesis to promote tumor growth.The Journal of Biological Chemistry May 2024SCAP plays a central role in controlling lipid homeostasis by activating SREBP-1, a master transcription factor in controlling fatty acid (FA) synthesis. However, how...
SCAP plays a central role in controlling lipid homeostasis by activating SREBP-1, a master transcription factor in controlling fatty acid (FA) synthesis. However, how SCAP expression is regulated in human cancer cells remains unknown. Here, we revealed that STAT3 binds to the promoter of SCAP to activate its expression across multiple cancer cell types. Moreover, we identified that STAT3 also concurrently interacts with the promoter of SREBF1 gene (encoding SREBP-1), amplifying its expression. This dual action by STAT3 collaboratively heightens FA synthesis. Pharmacological inhibition of STAT3 significantly reduces the levels of unsaturated FAs and phospholipids bearing unsaturated FA chains by reducing the SCAP-SREBP-1 signaling axis and its downstream effector SCD1. Examination of clinical samples from patients with glioblastoma, the most lethal brain tumor, demonstrates a substantial co-expression of STAT3, SCAP, SREBP-1, and SCD1. These findings unveil STAT3 directly regulates the expression of SCAP and SREBP-1 to promote FA synthesis, ultimately fueling tumor progression.
PubMed: 38718868
DOI: 10.1016/j.jbc.2024.107351 -
Scientific Reports May 2024Intramuscular fat (IMF) and backfat thickness (BFT) are critical economic traits impacting meat quality. However, the genetic variants controlling these traits need to...
Intramuscular fat (IMF) and backfat thickness (BFT) are critical economic traits impacting meat quality. However, the genetic variants controlling these traits need to be better understood. To advance knowledge in this area, we integrated RNA-seq and single nucleotide polymorphisms (SNPs) identified in genomic and transcriptomic data to generate a linkage disequilibrium filtered panel of 553,581 variants. Expression quantitative trait loci (eQTL) analysis revealed 36,916 cis-eQTLs and 14,408 trans-eQTLs. Association analysis resulted in three eQTLs associated with BFT and 24 with IMF. Functional enrichment analysis of genes regulated by these 27 eQTLs revealed noteworthy pathways that can play a fundamental role in lipid metabolism and fat deposition, such as immune response, cytoskeleton remodeling, iron transport, and phospholipid metabolism. We next used ATAC-Seq assay to identify and overlap eQTL and open chromatin regions. Six eQTLs were in regulatory regions, four in predicted insulators and possible CCCTC-binding factor DNA binding sites, one in an active enhancer region, and the last in a low signal region. Our results provided novel insights into the transcriptional regulation of IMF and BFT, unraveling putative regulatory variants.
Topics: Animals; Quantitative Trait Loci; Cattle; Polymorphism, Single Nucleotide; Chromatin; Adipose Tissue; Mutation; Linkage Disequilibrium; Genome-Wide Association Study; Gene Expression Regulation; Lipid Metabolism
PubMed: 38698200
DOI: 10.1038/s41598-024-60703-5 -
Nature Communications May 2024The LAT1-4F2hc complex (SLC7A5-SLC3A2) facilitates uptake of essential amino acids, hormones and drugs. Its dysfunction is associated with many cancers and...
The LAT1-4F2hc complex (SLC7A5-SLC3A2) facilitates uptake of essential amino acids, hormones and drugs. Its dysfunction is associated with many cancers and immune/neurological disorders. Here, we apply native mass spectrometry (MS)-based approaches to provide evidence of super-dimer formation (LAT1-4F2hc). When combined with lipidomics, and site-directed mutagenesis, we discover four endogenous phosphatidylethanolamine (PE) molecules at the interface and C-terminus of both LAT1 subunits. We find that interfacial PE binding is regulated by 4F2hc-R183 and is critical for regulation of palmitoylation on neighbouring LAT1-C187. Combining native MS with mass photometry (MP), we reveal that super-dimerization is sensitive to pH, and modulated by complex N-glycans on the 4F2hc subunit. We further validate the dynamic assemblies of LAT1-4F2hc on plasma membrane and in the lysosome. Together our results link PTM and lipid binding with regulation and localisation of the LAT1-4F2hc super-dimer.
Topics: Humans; Large Neutral Amino Acid-Transporter 1; Phosphatidylethanolamines; Lipoylation; Lysosomes; Cell Membrane; Amino Acid Transport System y+; HEK293 Cells; Protein Multimerization; Protein Binding; Mass Spectrometry; Mutagenesis, Site-Directed; Hydrogen-Ion Concentration; Membrane Proteins; Fusion Regulatory Protein 1, Heavy Chain; Adaptor Proteins, Signal Transducing
PubMed: 38697966
DOI: 10.1038/s41467-024-47948-4 -
Journal of the American Chemical Society May 2024The nanoscopic layer of water that directly hydrates biological membranes plays a critical role in maintaining the cell structure, regulating biochemical processes, and...
The nanoscopic layer of water that directly hydrates biological membranes plays a critical role in maintaining the cell structure, regulating biochemical processes, and managing intermolecular interactions at the membrane interface. Therefore, comprehending the membrane structure, including its hydration, is essential for understanding the chemistry of life. While cholesterol is a fundamental lipid molecule in mammalian cells, influencing both the structure and dynamics of cell membranes, its impact on the structure of interfacial water has remained unknown. We used surface-specific vibrational sum-frequency generation spectroscopy to study the effect of cholesterol on the structure and hydration of monolayers of the lipids 1,2-dipalmitoyl--glycero-3-phosphocholine (DPPC), 1,2-dioleoyl--glycero-3-phosphocholine (DOPC), and egg sphingomyelin (SM). We found that for the unsaturated lipid DOPC, cholesterol intercalates in the membrane without significantly changing the orientation of the lipid tails and the orientation of the water molecules hydrating the headgroups of DOPC. In contrast, for the saturated lipids DPPC and SM, the addition of cholesterol leads to clearly enhanced packing and ordering of the hydrophobic tails. It is also observed that the orientation of the water hydrating the lipid headgroups is enhanced upon the addition of cholesterol. These results are important because the orientation of interfacial water molecules influences the cell membranes' dipole potential and the strength and specificity of interactions between cell membranes and peripheral proteins and other biomolecules. The lipid nature-dependent role of cholesterol in altering the arrangement of interfacial water molecules offers a fresh perspective on domain-selective cellular processes, such as protein binding.
Topics: Cholesterol; Water; Cell Membrane; Phosphatidylcholines; Sphingomyelins; 1,2-Dipalmitoylphosphatidylcholine
PubMed: 38687869
DOI: 10.1021/jacs.4c00474