LA Biomedical Research Institute
LA Biomedical Research Institute
Stavropoulou V.,University of Basel |
Kaspar S.,Friedrich Miescher Institute for Biomedical Research |
Kaspar S.,University of Basel |
Brault L.,University of Basel |
And 13 more authors.
Cancer Cell | Year: 2016
To address the impact of cellular origin on acute myeloid leukemia (AML), we generated an inducible transgenic mouse model for MLL-AF9-driven leukemia. MLL-AF9 expression in long-term hematopoietic stem cells (LT-HSC) in vitro resulted in dispersed clonogenic growth and expression of genes involved in migration and invasion. In vivo, 20% LT-HSC-derived AML were particularly aggressive with extensive tissue infiltration, chemoresistance, and expressed genes related to epithelial-mesenchymal transition (EMT) in solid cancers. Knockdown of the EMT regulator ZEB1 significantly reduced leukemic blast invasion. By classifying mouse and human leukemias according to Evi1/EVI1 and Erg/ERG expression, reflecting aggressiveness and cell of origin, and performing comparative transcriptomics, we identified several EMT-related genes that were significantly associated with poor overall survival of AML patients. © 2016 Elsevier Inc.
Mishra N.N.,LA Biomedical Research Institute |
Mishra N.N.,University of California at Los Angeles |
Tran T.T.,University of Houston |
Seepersaud R.,University of California at San Francisco |
And 11 more authors.
Antimicrobial Agents and Chemotherapy | Year: 2017
Streptococcus mitis/oralis is an important pathogen, causing life-threatening infections such as endocarditis and severe sepsis in immunocompromised patients. The β-lactam antibiotics are the usual therapy of choice for this organism, but their effectiveness is threatened by the frequent emergence of resistance. The lipopeptide daptomycin (DAP) has been suggested for therapy against such resistant S. mitis/oralis strains due to its in vitro bactericidal activity and demonstrated efficacy against other Gram-positive pathogens. Unlike other bacteria, however, S. mitis/oralis has the unique ability to rapidly develop stable, high-level resistance to DAP upon exposure to the drug both in vivo and in vitro. Using isogenic DAP-susceptible and DAP-resistant S. mitis/oralis strain pairs, we describe a mechanism of resistance to both DAP and cationic antimicrobial peptides that involves loss-of-function mutations in cdsA (encoding a phosphatidate cytidylyltransferase). CdsA catalyzes the synthesis of cytidine diphosphate-diacylglycerol, an essential phospholipid intermediate for the production of membrane phosphatidylglycerol and cardiolipin. DAP-resistant S. mitis/oralis strains demonstrated a total disappearance of phosphatidylglycerol, cardiolipin, and anionic phospholipid microdomains from membranes. In addition, these strains exhibited cross-resistance to cationic antimicrobial peptides from human neutrophils (i.e., hNP-1). Interestingly, CdsA-mediated changes in phospholipid metabolism were associated with DAP hyperaccumulation in a small subset of the bacterial population, without any binding by the remaining larger population. Our results indicate that CdsA is the major mediator of high-level DAP resistance in S. mitis/oralis and suggest a novel mechanism of bacterial survival against attack by antimicrobial peptides of both innate and exogenous origins. © 2017 American Society for Microbiology. All Rights Reserved.
Chuang T.-D.,University of California at Los Angeles |
Chuang T.-D.,LA Biomedical Research Institute |
Khorram O.,University of California at Los Angeles |
Khorram O.,LA Biomedical Research Institute
Life Sciences | Year: 2017
Aims The objective of this study was to determine the underlying mechanism by which glucocorticoids (GCs) induce of miR-29c expression in vascular smooth muscle cells. Main methods QRT-PCR was used for miR-29c detection. Protein levels were determined by western blotting. Knockdown of SP1, DNMT1 and DNMT3A was achieved through transfection with their specific respective siRNAs. The effect of GCs on SP1 activity was determined by luciferase reporter assay and the methylation status in miR-29c promoter was detected by methylation specific PCR. CHIP assay was used to determine the binding ability of SP1 and glucocorticoid receptor (GR) in miR-29c promoter. Key findings Treatment of RASMC with SP1 siRNA or SP1 inhibitor, mithramycin A, as well as DNMT1 and DNMT3A siRNAs and an inhibitor of DNMTs, Decitabine, resulted in increased expression of miR-29c (P < 0.05). Treatment RASMC with dexamethasone (DEX, 0.1 μM) for 24 h reduced the expression of SP1 and phosphorylated SP1 at threonine 453 protein levels, repressed SP1 activity, and inhibited the expression of DNMT1 and DNMT3A proteins (P < 0.05). Treatment with mifepristone, a GR antagonist, blocked the inhibitory effect of DEX on DNMT1 and DNMT3A protein expression. DEX also suppressed SP1 binding ability in miR-29c promoter and inhibited methylation of miR-29c promoter (P < 0.05). Treatment of RASMC with DEX (0.1 μM) significantly (P < 0.05) increased the binding of GR to the miR-29c promoter. Significance The stimulatory effect of GCs on miR-29c expression is mediated by these three mechanisms: transcriptionally regulated by SP1, and epigenetically through a methylation-dependent process and GR. © 2017
PubMed | University of Barcelona, University of Houston, Wayne State University, University of California at Los Angeles and 2 more.
Type: | Journal: Antimicrobial agents and chemotherapy | Year: 2017
Streptococcus mitis is an important pathogen, causing life-threatening infections such as endocarditis and severe sepsis in immunocompromised patients. The -lactam antibiotics are the usual therapy of choice for this organism, but their effectiveness is threatened by the frequent emergence of resistance. The lipopeptide, daptomycin ( DAP: ), has been suggested for such resistant S. mitis, due to its in vitro bactericidal activity and demonstrated efficacy with other Gram-positive pathogens. Unlike other bacteria, however, S. mitis has the unique ability to rapidly develop stable, high-level resistance to DAP upon exposure to the drug, both in vivo and in vitro Using isogenic strain-pairs of DAP-susceptible and DAP-resistant S. mitis, we describe a mechanism of resistance to both DAP and cationic antimicrobial peptides that involves loss-of-function mutations in cdsA (encoding a phosphatidate cytidylyltransferase). CdsA catalyzes the synthesis of cytidine-diphosphate diacylglycerol, an essential phospholipid intermediate for the production of membrane phosphatidylglycerol and cardiolipin. DAP-resistant S. mitis demonstrated a total disappearance of phosphatidylglycerol, cardiolipin and anionic phospholipid microdomains from membranes. In addition, these strains exhibited cross-resistance to cationic antimicrobial peptides from human neutrophils (i.e., hNP-1). Interestingly, CdsA mediated changes in phospholipid metabolism were associated with DAP hyper-accumulation in a small subset of the bacterial population, without any binding by the remaining larger population. Our results indicate that CdsA is the major mediator of high-level DAP resistance in S. mitis and suggest a novel mechanism of bacterial survival to the attack by antimicrobial peptides of both innate and exogenous origins.
Zhang J.,University of California at Los Angeles |
Khvorostov I.,University of California at Los Angeles |
Hong J.S.,University of California at Los Angeles |
Oktay Y.,University of California at Los Angeles |
And 14 more authors.
EMBO Journal | Year: 2011
It has been assumed, based largely on morphologic evidence, that human pluripotent stem cells (hPSCs) contain underdeveloped, bioenergetically inactive mitochondria. In contrast, differentiated cells harbour a branched mitochondrial network with oxidative phosphorylation as the main energy source. A role for mitochondria in hPSC bioenergetics and in cell differentiation therefore remains uncertain. Here, we show that hPSCs have functional respiratory complexes that are able to consume O 2 at maximal capacity. Despite this, ATP generation in hPSCs is mainly by glycolysis and ATP is consumed by the F 1 F 0 ATP synthase to partially maintain hPSC mitochondrial membrane potential and cell viability. Uncoupling protein 2 (UCP2) plays a regulating role in hPSC energy metabolism by preventing mitochondrial glucose oxidation and facilitating glycolysis via a substrate shunting mechanism. With early differentiation, hPSC proliferation slows, energy metabolism decreases, and UCP2 is repressed, resulting in decreased glycolysis and maintained or increased mitochondrial glucose oxidation. Ectopic UCP2 expression perturbs this metabolic transition and impairs hPSC differentiation. Overall, hPSCs contain active mitochondria and require UCP2 repression for full differentiation potential. © 2011 European Molecular Biology Organization | All Rights Reserved.
Fischer A.,University of Geneva |
Yang S.-J.,LA Biomedical Research Institute |
Bayer A.S.,LA Biomedical Research Institute |
Bayer A.S.,University of California at Los Angeles |
And 11 more authors.
Journal of Antimicrobial Chemotherapy | Year: 2011
Objectives: The development of daptomycin resistance in Staphylococcus aureus is associated with clinical treatment failures. The mechanism(s) of such resistance have not been clearly defined. Methods: We studied an isogenic daptomycin-susceptible (DAPS) and daptomycin-resistant (DAPR) S. aureus strain pair (616; 701) from a patient with relapsing endocarditis during daptomycin treatment, using comparative transcriptomic and proteomic techniques. Results: Minor differences in the genome content were found between strains by DNA hybridization. Transcriptomic analyses identified a number of genes differentially expressed in important functional categories: cell division; metabolism of bacterial envelopes; and global regulation. Of note, the DAP. R isolate exhibited reduced expression of the major cell wall autolysis gene coincident with the up-regulation of genes involved in cell wall teichoic acid production. Using quantitative (q)RT-PCR on the gene cadre putatively involved in cationic peptide resistance, we formulated a putative regulatory network compatible with microarray data sets, mainly implicating bacterial envelopes. Of interest, qRT-PCR of this same gene cadre from two distinct isogenic DAP. S/DAP. R clinical strain pairs revealed evidence of other strain-dependent networks operative in the DAP. R phenotype. Comparative proteomics of 616 versus 701 revealed a differential abundance of proteins in various functional categories, including cell wall-associated targets and biofilm formation proteins. Phenotypically, strains 616 and 701 showed major differences in their ability to develop bacterial biofilms in the presence of the antibacterial lipid, oleic acid. Conclusions: Compatible with previous in vitro observations, in vivo-acquired DAPR in S. aureus is a complex, multistep phenomenon involving: (i) strain-dependent phenotypes; (ii) transcriptome adaptation; and (iii) modification of the lipid and protein contents of cellular envelopes. © The Author 2011. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.
Vaitheesvaran B.,Yeshiva University |
Xu J.,University of Southern California |
Yee J.,University of California at Los Angeles |
Lu Q.-Y.,University of California at Los Angeles |
And 5 more authors.
Metabolomics | Year: 2015
Cancer metabolism is characterized by increased macromolecular syntheses through coordinated increases in energy and substrate metabolism. The observation that cancer cells produce lactate in an environment of oxygen sufficiency (aerobic glycolysis) is a central theme of cancer metabolism known as the Warburg effect. Aerobic glycolysis in cancer metabolism is accompanied by increased pentose cycle and anaplerotic activities producing energy and substrates for macromolecular synthesis. How these processes are coordinated is poorly understood. Recent advances have focused on molecular regulation of cancer metabolism by oncogenes and tumor suppressor genes which regulate numerous enzymatic steps of central glucose metabolism. In the past decade, new insights in cancer metabolism have emerged through the application of stable isotopes particularly from 13C carbon tracing. Such studies have provided new evidence for system-wide changes in cancer metabolism in response to chemotherapy. Interestingly, experiments using metabolic inhibitors on individual biochemical pathways all demonstrate similar system-wide effects on cancer metabolism as in targeted therapies. Since biochemical reactions in the Warburg effect place competing demands on available precursors, high energy phosphates and reducing equivalents, the cancer metabolic system must fulfill the condition of balance of flux (homeostasis). In this review, the functions of the pentose cycle and of the tricarboxylic acid (TCA) cycle in cancer metabolism are analyzed from the balance of flux point of view. Anticancer treatments that target molecular signaling pathways or inhibit metabolism alter the invasive or proliferative behavior of the cancer cells by their effects on the balance of flux (homeostasis) of the cancer metabolic phenotype. © 2014, Springer Science+Business Media New York.
Xu J.,Southern California Research Center for and Cirrhosis |
Xu J.,University of Southern California |
Xu J.,Greater Los Angeles Healthcare System |
Chi F.,Southern California Research Center for and Cirrhosis |
And 9 more authors.
Journal of Clinical Investigation | Year: 2015
Metabolic reprogramming is implicated in macrophage activation, but the underlying mechanisms are poorly understood. Here, we demonstrate that the NOTCH1 pathway dictates activation of M1 phenotypes in isolated mouse hepatic macrophages (HMacs) and in a murine macrophage cell line by coupling transcriptional upregulation of M1 genes with metabolic upregulation of mitochondrial oxidative phosphorylation and ROS (mtROS) to augment induction of M1 genes. Enhanced mitochondrial glucose oxidation was achieved by increased recruitment of the NOTCH1 intracellular domain (NICD1) to nuclear and mitochondrial genes that encode respiratory chain components and by NOTCH-dependent induction of pyruvate dehydrogenase phosphatase 1 (Pdp1) expression, pyruvate dehydrogenase activity, and glucose flux to the TCA cycle. As such, inhibition of the NOTCH pathway or Pdp1 knockdown abrogated glucose oxidation, mtROS, and M1 gene expression. Conditional NOTCH1 deficiency in the myeloid lineage attenuated HMac M1 activation and inflammation in a murine model of alcoholic steatohepatitis and markedly reduced lethality following endotoxin-mediated fulminant hepatitis in mice. In vivo monocyte tracking further demonstrated the requirement of NOTCH1 for the migration of blood monocytes into the liver and subsequent M1 differentiation. Together, these results reveal that NOTCH1 promotes reprogramming of mitochondrial metabolism for M1 macrophage activation.
Wahjudi P.N.,LA Biomedical Research Institute |
Yee J.K.,LA Biomedical Research Institute |
Yee J.K.,University of California at Los Angeles |
Martinez S.R.,LA Biomedical Research Institute |
And 10 more authors.
Journal of Lipid Research | Year: 2011
Cardiolipin (CL) is a unique phospholipid (PL) found in the mitochondria of mammalian cells. CL remodeling is accompanied by turnover of its fatty acid acyl groups. Abnormalities in CL remodeling have been found in Barth's syndrome, diabetes, and obesity. The objective of this study was to determine nonessential fatty acid turnover in CL and phosphatidylethanolamine (PE) in the rat heart in vivo. Sprague-Dawley rats were fed either a regular chow or a high-fat diet for 15 weeks, and consumed 6% deuterium-enriched drinking water as a tracer for 14 days. CL and PE were extracted from cardiac tissue and isolated by TLC. Fatty acids from CL, PE, and plasma were analyzed by GC/MS for deuterium incorporation. Results showed oleate and vaccenate turnover were the highest in CL whereas palmitate and stearate turnover were low. Among the nonessential fatty acids in PE, turnover of stearate and vaccenate were the highest. The high turnover rate in vaccenate was unexpected, because vaccenate previously had no known metabolic or physiologic function. In conclusion, the similarly high turnover rates of both oleate and vaccenate readily suggest that remodeling is an important functional aspect of PL metabolism in CL. Copyright © 2011 by the American Society for Biochemistry and Molecular Biology, Inc.
Kholdani C.A.,Stanford University |
Oudiz R.J.,LA Biomedical Research Institute |
Fares W.H.,Yale University
Seminars in Respiratory and Critical Care Medicine | Year: 2015
The right heart failure (RHF) syndrome is a pathophysiologically complex state commonly associated with dysfunction of the right ventricle (RV). The normal RV is suited for its purposes of distributing venous blood to the low-resistance pulmonary circulation. Myriad stresses imposed upon it, though, can ultimately result in its failure, with the threat of cardiovascular collapse being the most dreaded outcome. Decreased cardiac output with increased central venous pressures are hemodynamic hallmarks of this highly morbid condition. Proper management of RHF is predicated on the accurate assessment of the key hemodynamic and clinical components signaling the syndrome that is the result of the failing RV. Appropriate use of diagnostic tools is paramount for understanding the key components of RV function: the preload state of the RV, its contractility, and the afterload burden placed on it. In making these assessments, it remains crucial to understand the limitations of these tools when managing RHF in the intensive care unit. An understanding of each of these components allows for the understanding of the physiology and the clinical presentation which can guide the use of therapies appropriately tailored to manage the condition. © 2015 by Thieme Medical Publishers, Inc.