المؤلفون: Jianfang Ning, Jie Li, Shan Zhu, Ming Li, Andrew S. Venteicher, Birra Taha, Johnny C. Akers, Clark C. Chen, Tomoyuki Koga

المصدر: Neuro Oncol

مصطلحات موضوعية: chemistry.chemical_classification, Cancer Research, education.field_of_study, Chemistry, Lactate dehydrogenase A, Metabolism, 26th Annual Meeting & Education Day of the Society for Neuro-Oncology, Chromatin remodeling, Chromatin, Cell biology, chemistry.chemical_compound, Crosstalk (biology), Enzyme, Oncology, Lactate dehydrogenase, Glycolysis, Neurology (clinical), education

الوصف: INTRODUCTION Lactate dehydrogenase A (LDHA) encodes an enzyme that catalyzes the inter-conversion between pyruvate and lactate in glycolysis. Here, we demonstrate that LDHA mediates a novel role in DNA repair independent of this metabolic function. METHODS siRNA screen, The Cancer Genome Atlas (TCGA) survival analysis, ionizing radiation (IR), g-H2AX, and chromatin assays, site-directed mutagenesis. RESULTS In an orthogonal siRNA-informatic screen to identify genes 1) when silenced caused IR sensitivity in patient-derived glioblastoma lines and 2) lowered expression is associated with improved survival in TCGA, LDHA surfaced as the top candidate. The survival association was validated by LDHA immunohistochemical staining in an independent collection of glioblastoma samples. In vitro and in vivo, silencing of LDHA sensitized glioblastoma lines to IR and enhanced radiation-induced g-H2AX accumulation. Such sensitization was not observed after treatment with an LDHA inhibitor, suggesting the metabolic function of LDHA is distinct from its role in DNA repair. Supporting this hypothesis, truncation mutations that suppressed the LDHA glycolysis function minimally affected its role in DNA repair. Mechanistically, cytoplasmic LDHA translocates into the nucleus in response to IR. This translocation was associated with subsequent chromatin transition into an open conformation and enhanced homologous recombination. CONCLUSION The novel LDHA function in DNA repair suggests intricate crosstalks between glycolytic metabolism and DNA repair, offering a new platform for glioblastoma therapeutic development.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::d4c82d07a96d11e88ffbbd36c01b97dfTest
https://europepmc.org/articles/PMC8598535Test/

المؤلفون: Dona R. Wisidagama, Carl S. Thummel

المصدر: G3: Genes, Genomes, Genetics, Vol 9, Iss 11, Pp 3623-3630 (2019)

مصطلحات موضوعية: Enterocyte, Mitochondrion, Biology, QH426-470, 03 medical and health sciences, chemistry.chemical_compound, 0302 clinical medicine, stem cells, Lactate dehydrogenase, medicine, Genetics, Inner mitochondrial membrane, Molecular Biology, Genetics (clinical), 030304 developmental biology, 0303 health sciences, fungi, JAK-STAT signaling pathway, intestinal homeostasis, Cell biology, mitochondria, medicine.anatomical_structure, chemistry, Mitochondrial matrix, Signal transduction, Stem cell, metabolism, 030217 neurology & neurosurgery

الوصف: Multiple signaling pathways in the adult Drosophila enterocyte sense cellular damage or stress and signal to intestinal stem cells (ISCs) to undergo proliferation and differentiation, thereby maintaining intestinal homeostasis. Here we show that misregulation of mitochondrial pyruvate metabolism in enterocytes can stimulate ISC proliferation and differentiation. Our studies focus on the Mitochondrial Pyruvate Carrier (MPC), which is an evolutionarily-conserved protein complex that resides in the inner mitochondrial membrane and transports cytoplasmic pyruvate into the mitochondrial matrix. Loss of MPC function in enterocytes induces Unpaired cytokine expression, which activates the JAK/STAT pathway in ISCs, promoting their proliferation. Upd3 and JNK signaling are required in enterocytes for ISC proliferation, indicating that this reflects a canonical non-cell autonomous damage response. Disruption of lactate dehydrogenase in enterocytes has no effect on ISC proliferation but it suppresses the proliferative response to a loss of enterocyte MPC function, suggesting that lactate contributes to this pathway. These studies define an important role for cellular pyruvate metabolism in differentiated enterocytes to maintain stem cell proliferation rates.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::dbaae6dc5464f543a9c8f4bfb3e08907Test
http://g3journal.org/lookup/doi/10.1534/g3.119.400633Test

المؤلفون: Françoise Van Bambeke, Fatima Mouaden, Marie-Paule Mingeot-Leclercq, Maritza Barcia-Macay, Paul M. Tulkens

المصدر: Journal of Antimicrobial Chemotherapy

مصطلحات موضوعية: Microbiology (medical), Time Factors, Lipoglycopeptide, vancomycin, Biology, Cell Fractionation, Cell Line, lipids, chemistry.chemical_compound, Mice, Telavancin, Microscopy, Electron, Transmission, Lysosome, Lactate dehydrogenase, medicine, Animals, Pharmacology (medical), Carbon Radioisotopes, membrane, Cells, Cultured, Phospholipids, Antibacterial agent, Original Research, Pharmacology, cellular pharmacokinetics, Macrophages, Oritavancin, glycopeptides, Lipoglycopeptides, Lipid metabolism, Fibroblasts, Cell biology, Anti-Bacterial Agents, Rats, Infectious Diseases, medicine.anatomical_structure, Aminoglycosides, Cholesterol, Biochemistry, chemistry, Lysosomes, Intracellular, medicine.drug, oritavancin

الوصف: Background Telavancin is a lipoglycopeptide with multiple mechanisms of action that include membrane-destabilizing effects towards bacterial cells. It shows bactericidal activity against forms of Staphylococcus aureus (phagolysosomal infection) with different resistance phenotypes [methicillin-resistant S. aureus, vancomycin-intermediate S. aureus or vancomycin-resistant S. aureus]. We examine here the uptake, efflux and intracellular distribution of telavancin in eukaryotic cells as well as its potential to induce lysosomal changes (in comparison with vancomycin and oritavancin). Methods J774 macrophages and rat embryo fibroblasts were exposed for up to 24 and 72 h to telavancin (5–90 mg/L). The following studies were performed: measurement of 14C-labelled telavancin cellular uptake and subcellular distribution (cell fractionation), determination of pericellular membrane integrity (lactate dehydrogenase release), electron microscopy with morphometric analysis of changes in lysosome size and determination of total phospholipid and cholesterol content. Results The uptake of telavancin proceeded linearly as a function of time and concentration in both cell types (clearance rate of ∼10 mL/g of protein/h). Efflux (macrophages) was ∼5.7-fold slower. Telavancin subcellular distribution was superimposable on that of a lysosomal marker (N-acetyl-β-hexosaminidase). It did not cause an increase in the release of lactate dehydrogenase and did not induce significant increases in total phospholipid or cholesterol content. It caused only mild morphological lysosomal alterations (similar to vancomycin and much less than oritavancin by morphometric analysis). Conclusions Telavancin is taken up by eukaryotic cells and localizes in lysosomes, causing mild morphological alterations without evidence of lipid metabolism alterations. These data support our observations that telavancin is active against intracellular S. aureus.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::077fcf2db7c16463238598fe22850937Test
http://europepmc.org/articles/PMC2386079Test

المؤلفون: Michael O. Frederick, Kyriacos C. Nicolaou, Keith T. LePage, Thomas F. Murray, Zhengyu Cao

مصطلحات موضوعية: Neurotoxicology, Caspase 3, Apoptosis, Neocortex, Cysteine Proteinase Inhibitors, Toxicology, Amino Acid Chloromethyl Ketones, Mice, Necrosis, Structure-Activity Relationship, medicine, Azaspiracid, Animals, Homeostasis, Humans, Shellfish Poisoning, Spiro Compounds, Caspase, Cells, Cultured, Neurons, biology, L-Lactate Dehydrogenase, Neurotoxicity, medicine.disease, Embryo, Mammalian, Molecular biology, Caspase Inhibitors, Cell biology, biology.protein, Calcium, Marine Toxins, Efflux, Signal transduction, Marine toxin, Signal Transduction

الوصف: Azaspiracids (AZAs) are a novel group of marine phycotoxins that have been associated with severe human intoxication. We found that AZA-1 exposure increased lactate dehydrogense (LDH) efflux in murine neocortical neurons. AZA-1 also produced nuclear condensation and stimulated caspase-3 activity with an half maximal effective concentration (EC(50)) value of 25.8 nM. These data indicate that AZA-1 triggers neuronal death in neocortical neurons by both necrotic and apoptotic mechanisms. An evaluation of the structure-activity relationships of AZA analogs on LDH efflux and caspase-3 activation demonstrated that the full structure of AZAs was required to produce necrotic or apoptotic cell death. The similar potencies of AZA-1 to stimulate LDH efflux and caspase-3 activation and the parallel structure-activity relationships of azaspiracid analogs in the two assays are consistent with a common molecular target for both responses. To explore the molecular mechanism for AZA-1-induced neurotoxicity, we assessed the influence of AZA-1 on Ca(2+) homeostasis. AZA-1 suppressed spontaneous Ca(2+) oscillations (EC(50) = 445 nM) in neocortical neurons. A distinct structure-activity profile was found for inhibition of Ca(2+) oscillations where both the full structure as well as analogs containing only the FGHI domain attached to a phenyl glycine methyl ester moiety were potent inhibitors. The molecular targets for inhibition of spontaneous Ca(2+) oscillations and neurotoxicity may therefore differ. The caspase protease inhibitor Z-VAD-FMK produced a complete elimination of AZA-1-induced LDH efflux and nuclear condensation in neocortical neurons. Although the molecular target for AZA-induced neurotoxicity remains to be established, these results demonstrate that the observed neurotoxicity is dependent on a caspase signaling pathway.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::61d6891235cba7a43402323c874bc792Test
https://europepmc.org/articles/PMC2840215Test/

المؤلفون: Gloria I. Viboud, James B. Bliska

مصطلحات موضوعية: rac1 GTP-Binding Protein, Cell Membrane Permeability, Biology, Yersinia, General Biochemistry, Genetics and Molecular Biology, Article, Ion Channels, Type three secretion system, Cell membrane, Bacterial Proteins, medicine, Yersinia pseudotuberculosis, Humans, Secretion, Molecular Biology, Actin, General Immunology and Microbiology, L-Lactate Dehydrogenase, Effector, Cytotoxins, General Neuroscience, Cell Membrane, biology.organism_classification, Translocon, Actins, Cell biology, Cysteine Endopeptidases, medicine.anatomical_structure, rhoA GTP-Binding Protein, Bacterial Outer Membrane Proteins, HeLa Cells

الوصف: The bacterial pathogen Yersinia pseudotuberculosis uses type III secretion machinery to translocate Yop effector proteins through host cell plasma membranes. A current model suggests that a type III translocation channel is inserted into the plasma membrane, and if Yops are not present to fill the channel, the channel will form a pore. We examined the possibility that Yops act within the host cell to prevent pore formation. Yop– mutants of Y.pseudotuberculosis were assayed for pore-forming activity in HeLa cells. A YopE– mutant exhibited high levels of pore-forming activity. The GTPase-downregulating function of YopE was required to prevent pore formation. YopE+ bacteria had increased pore-forming activity when HeLa cells expressed activated Rho GTPases. Pore formation by YopE– bacteria required actin polymerization. F-actin was concentrated at sites of contact between HeLa cells and YopE– bacteria. The data suggest that localized actin polymerization, triggered by the type III machinery, results in pore formation in cells infected with YopE– bacteria. Thus, translocated YopE inhibits actin polymerization to prevent membane damage to cells infected with wild-type bacteria.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::2348a7c14443e1c69036a24ce8b39333Test
https://europepmc.org/articles/PMC125656Test/