Christopher K Glass

University of California, San Diego, San Diego, California, United States

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Publications (274)4021.55 Total impact

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    ABSTRACT: A large portion of the human genome is transcribed into RNAs without known protein-coding functions, far outnumbering coding transcription units. Extensive studies of long noncoding RNAs (lncRNAs) have clearly demonstrated that they can play critical roles in regulating gene expression, development, and diseases, acting both as transcriptional activators and repressors. More recently, enhancers have been found to be broadly transcribed, resulting in the production of enhancer-derived RNAs, or eRNAs. Here, we review emerging evidence suggesting that at least some eRNAs contribute to enhancer function. We discuss these findings with respect to potential mechanisms of action of eRNAs and other ncRNAs in regulated gene expression.
    Trends in Biochemical Sciences 03/2014; · 13.08 Impact Factor
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    ABSTRACT: Huntington's disease (HD) is a fatal neurodegenerative disorder caused by an extended polyglutamine repeat in the N terminus of the Huntingtin protein (HTT). Reactive microglia and elevated cytokine levels are observed in the brains of HD patients, but the extent to which neuroinflammation results from extrinsic or cell-autonomous mechanisms in microglia is unknown. Using genome-wide approaches, we found that expression of mutant Huntingtin (mHTT) in microglia promoted cell-autonomous pro-inflammatory transcriptional activation by increasing the expression and transcriptional activities of the myeloid lineage-determining factors PU.1 and C/EBPs. We observed elevated levels of PU.1 and its target genes in the brains of mouse models and individuals with HD. Moreover, mHTT-expressing microglia exhibited an increased capacity to induce neuronal death ex vivo and in vivo in the presence of sterile inflammation. These findings suggest a cell-autonomous basis for enhanced microglia reactivity that may influence non-cell-autonomous HD pathogenesis.
    Nature Neuroscience 03/2014; · 15.25 Impact Factor
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    ABSTRACT: Eicosanoids, including prostaglandins (PG) and leukotrienes, are lipid mediators derived from arachidonic acid. A quantitative and biochemical level understanding of eicosanoid metabolism would aid in understanding the mechanisms that govern inflammatory processes. Here, we present a combined experimental and computational approach to understanding the biochemical basis of eicosanoid metabolism in macrophages. Lipidomic and transcriptomic measurements and analyses reveal temporal and dynamic changes of the eicosanoid metabolic network in mouse bone marrow-derived macrophages (BMDM) upon stimulation of the Toll-like receptor 4 with Kdo2-Lipid A (KLA) and stimulation of the P2X7 purinergic receptor with adenosine 5'-triphosphate. Kinetic models were developed for the cyclooxygenase (COX) and lipoxygenase branches of arachidonic acid metabolism, and then the rate constants were estimated with a data set from ATP-stimulated BMDM, using a two-step matrix-based approach employing a constrained least-squares method followed by nonlinear optimization. The robustness of the model was validated through parametric sensitivity, uncertainty analysis, and predicting an independent dataset from KLA-primed ATP-stimulated BMDM by allowing the parameters to vary within the uncertainty range of the calculated parameters. We analyzed the functional coupling between COX isozymes and terminal enzymes by developing a PGH2-divided model. This provided evidence for the functional coupling between COX-2 and PGE2 synthase, between COX-1/COX-2 and PGD2 synthase, and also between COX-1 and thromboxane A2 synthase. Further, these functional couplings were experimentally validated using COX-1 and COX-2 selective inhibitors. The resulting fluxomics analysis demonstrates that the "multi-omics" systems biology approach can define the complex machinery of eicosanoid networks.
    Biophysical Journal 02/2014; 106(4):966-75. · 3.67 Impact Factor
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    ABSTRACT: Global run-on sequencing (GRO-seq) is a recent addition to the series of high-throughput sequencing methods that enables new insights into transcriptional dynamics within a cell. However, GRO-sequencing presents new algorithmic challenges, as existing analysis platforms for ChIP-seq and RNA-seq do not address the unique problem of identifying transcriptional units de novo from short reads located all across the genome. Here, we present a novel algorithm for de novo transcript identification from GRO-sequencing data, along with a system that determines transcript regions, stores them in a relational database and associates them with known reference annotations. We use this method to analyze GRO-sequencing data from primary mouse macrophages and derive novel quantitative insights into the extent and characteristics of non-coding transcription in mammalian cells. In doing so, we demonstrate that Vespucci expands existing annotations for mRNAs and lincRNAs by defining the primary transcript beyond the polyadenylation site. In addition, Vespucci generates assemblies for un-annotated non-coding RNAs such as those transcribed from enhancer-like elements. Vespucci thereby provides a robust system for defining, storing and analyzing diverse classes of primary RNA transcripts that are of increasing biological interest.
    Nucleic Acids Research 12/2013; · 8.28 Impact Factor
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    ABSTRACT: 25-hydroxycholesterol (25OHC) is an enzymatically-derived oxidation product of cholesterol that modulates lipid metabolism and immunity. 25OHC is synthesized in response to interferons and exerts broad anti-viral activity by as yet poorly characterized mechanisms. To gain further insights into the basis for anti-viral activity, we evaluated time-dependent responses of the macrophage lipidome and transcriptome to 25OHC treatment. In addition to altering specific aspects of cholesterol and sphingolipid metabolism, we found that 25OHC activates integrated stress response (ISR) genes and reprograms protein translation. Effects of 25OHC on ISR gene expression were independent of liver X receptors (LXRs) and sterol response element binding proteins (SREBPs) and instead primarily resulted from activation of the GCN2/eIF2α/ATF4 branch of the ISR pathway. These studies reveal that 25OHC activates the integrated stress response, which may contribute to its anti-viral activity.
    Journal of Biological Chemistry 11/2013; · 4.65 Impact Factor
  • Dawn Zhang, C Glass
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    ABSTRACT: The ability to regulate gene expression in a cell-specific manner is a feature of many broadly expressed signal-dependent transcription factors, including nuclear hormone receptors and transcription factors that are activated by cell surface receptors for extracellular signals. As the most plastic cells of the hematopoietic system, macrophages are responsive to a wide spectrum of regulatory molecules and provide a robust model system for investigation of the basis for cell-specific transcriptional responses at a genome-wide level. Here, we review recent studies suggesting a model in which macrophage-specific actions of signal-dependent transcription factors are the consequence of priming functions of lineage-determining transcription factors that include PU.1, AP1 factors, and CEBPs. These mechanisms can be generalized to lineage-determining factors in other cell types. We also discuss recent findings relating lineage-determining and signal-dependent transcription factor activity to alterations in the epigenetic landscape as well as the production and function of enhancer RNAs. These findings have implications for the understanding of how natural genetic variation impacts cell-specific programs of gene expression and suggest new approaches for altering gene expression in vivo.
    Journal of Molecular Endocrinology 10/2013; · 3.58 Impact Factor
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    ABSTRACT: The mechanisms by which genetic variation affects transcription regulation and phenotypes at the nucleotide level are incompletely understood. Here we use natural genetic variation as an in vivo mutagenesis screen to assess the genome-wide effects of sequence variation on lineage-determining and signal-specific transcription factor binding, epigenomics and transcriptional outcomes in primary macrophages from different mouse strains. We find substantial genetic evidence to support the concept that lineage-determining transcription factors define epigenetic and transcriptomic states by selecting enhancer-like regions in the genome in a collaborative fashion and facilitating binding of signal-dependent factors. This hierarchical model of transcription factor function suggests that limited sets of genomic data for lineage-determining transcription factors and informative histone modifications can be used for the prioritization of disease-associated regulatory variants.
    Nature 10/2013; · 38.60 Impact Factor
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    ABSTRACT: Macrophage-mediated inflammation is a major contributor to obesity-associated insulin resistance. The corepressor NCoR interacts with inflammatory pathway genes in macrophages, suggesting that its removal would result in increased activity of inflammatory responses. Surprisingly, we find that macrophage-specific deletion of NCoR instead results in an anti-inflammatory phenotype along with robust systemic insulin sensitization in obese mice. We present evidence that derepression of LXRs contributes to this paradoxical anti-inflammatory phenotype by causing increased expression of genes that direct biosynthesis of palmitoleic acid and ω3 fatty acids. Remarkably, the increased ω3 fatty acid levels primarily inhibit NF-κB-dependent inflammatory responses by uncoupling NF-κB binding and enhancer/promoter histone acetylation from subsequent steps required for proinflammatory gene activation. This provides a mechanism for the in vivo anti-inflammatory insulin-sensitive phenotype observed in mice with macrophage-specific deletion of NCoR. Therapeutic methods to harness this mechanism could lead to a new approach to insulin-sensitizing therapies.
    Cell 09/2013; 155(1):200-14. · 31.96 Impact Factor
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    ABSTRACT: Macrophage activation, by lipopolysaccharide and adenosine triphosphate (ATP), has been studied extensively since this model system mimics the physiological context of bacterial infection and subsequent inflammatory responses. Previous studies on macrophages elucidated the biological roles of caspase-1 in post-translational activation of interleukin (IL)-1β and IL-18 in inflammation and apoptosis. However, the results from these studies focused only on a small number of factors. To better understand the host response, we have performed a high-throughput study of Kdo2-Lipid A (KLA) primed macrophages stimulated with ATP(#). The study suggests that treating mouse bone marrow-derived macrophages with KLA and ATP produces "synergistic" effects that are not seen with treatment of KLA or ATP alone. The synergistic regulation of genes related to immunity, apoptosis and lipid metabolism is observed in a time-dependent manner. The synergistic effects are produced by nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and activator protein (AP)-1 through regulation of their target cytokines. The synergistically regulated cytokines then activate Signal Transducer and Activator of Transcription (STAT) factors that result in enhanced immunity, apoptosis and lipid metabolism; STAT1 enhances immunity by promoting anti-microbial factors, and STAT3 contributes to downregulation of cell cycle and upregulation of apoptosis. STAT1 and STAT3 also regulate glycerolipid and eicosanoid metabolism, respectively. Further, western blot analysis for STAT1 and STAT3 showed that the changes in transcriptomic levels were consistent with their proteomic levels. In summary, this study shows the synergistic interaction between the Toll-like receptor and purinergic receptor signaling during macrophage activation upon bacterial infection.(#) AVAILABILITY: Time-course data of transcriptomics and lipidomics can be queried or downloaded from shankar@ucsd.eduSupplementary material is available from Bioinformatics online.
    Bioinformatics 08/2013; · 5.47 Impact Factor
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    ABSTRACT: Conjugated linoleic acid (CLA) has the unique property of inducing regression of pre-established murine atherosclerosis. Understanding the mechanism(s) involved may help identify endogenous pathways that reverse human atherosclerosis. Here, we provide evidence that CLA inhibits foam cell formation via regulation of the nuclear receptor coactivator, peroxisome proliferator-activated receptor (PPAR)-γ coactivator (PGC)-1α, and that macrophage PGC-1α plays a role in atheroprotection in vivo. PGC-1α was identified as a hub gene within a cluster in the aorta of the apoE(-/-) mouse in the CLA-induced regression model. PGC-1α was localized to macrophage/foam cells in the murine aorta where its expression was increased during CLA-induced regression. PGC-1α expression was also detected in macrophages in human atherosclerosis and was inversely linked to disease progression in patients with the disease. Deletion of PGC-1α in bone marrow derived macrophages promoted, whilst over expression of the gene inhibited foam cell formation. Importantly, macrophage specific deletion of PGC-1α accelerated atherosclerosis in the LDLR(-/-) mouse in vivo. These novel data support a functional role for PGC-1α in atheroprotection.
    EMBO Molecular Medicine 08/2013; · 7.80 Impact Factor
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    Nathanael J Spann, Christopher K Glass
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    ABSTRACT: Intermediates in the cholesterol-biosynthetic pathway and oxysterol derivatives of cholesterol regulate diverse cellular processes. Recent studies have expanded the appreciation of their roles in controlling the functions of cells of the innate and adaptive immune systems. Here we review recent literature reporting on the biological functions of sterol intermediates and oxysterols, acting through transcription factors such as the liver X receptors (LXRs), sterol regulatory element-binding proteins (SREBPs) and the G protein-coupled receptor EBI2, in regulating the differentiation and population expansion of cells of the innate and adaptive immune systems, their responses to inflammatory mediators, their effects on the phagocytic functions of macrophages and their effects on antiviral activities and the migration of immune cells. Such findings have raised many new questions about the production of endogenous bioactive sterols and oxysterols and their mechanisms of action in the immune system.
    Nature Immunology 08/2013; 14(9):893-900. · 26.20 Impact Factor
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    ABSTRACT: Recent studies suggest a hierarchical model in which lineage-determining factors act in a collaborative manner to select and prime cell-specific enhancers, thereby enabling signal-dependent transcription factors to bind and function in a cell-type-specific manner. Consistent with this model, TLR4 signaling primarily regulates macrophage gene expression through a pre-existing enhancer landscape. However, TLR4 signaling also induces priming of ∼3,000 enhancer-like regions de novo, enabling visualization of intermediates in enhancer selection and activation. Unexpectedly, we find that enhancer transcription precedes local mono- and dimethylation of histone H3 lysine 4 (H3K4me1/2). H3K4 methylation at de novo enhancers is primarily dependent on the histone methyltransferases Mll1, Mll2/4, and Mll3 and is significantly reduced by inhibition of RNA polymerase II elongation. Collectively, these findings suggest an essential role of enhancer transcription in H3K4me1/2 deposition at de novo enhancers that is independent of potential functions of the resulting eRNA transcripts.
    Molecular cell 08/2013; 51(3):310-25. · 14.61 Impact Factor
  • Joshua D Stender, Christopher K Glass
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    ABSTRACT: Toll-like receptors (TLRs) play important roles in initiation of innate immune responses and promotion of pathological forms of inflammation. Recent technological advances have enabled the visualization of transcription factor binding and histone modifications in response to TLR signaling at genome-wide levels. Findings emerging from these studies are beginning to provide a picture of how signal-dependent transcription factors regulate the inflammatory response in a cell-specific manner by controlling the recruitment of nucleosome remodeling factors and histone modifying enzymes. Of particular interest, new small molecule inhibitors have been developed that influence inflammatory responses by altering the reading or erasure of histone modifications required for inflammatory gene activation. These findings suggest new approaches for treatment of inflammatory diseases.
    Current Opinion in Pharmacology 06/2013; · 5.44 Impact Factor
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    ABSTRACT: The functional importance of gene enhancers in regulated gene expression is well established. In addition to widespread transcription of long non-coding RNAs (lncRNAs) in mammalian cells, bidirectional ncRNAs are transcribed on enhancers, and are thus referred to as enhancer RNAs (eRNAs). However, it has remained unclear whether these eRNAs are functional or merely a reflection of enhancer activation. Here we report that in human breast cancer cells 17β-oestradiol (E2)-bound oestrogen receptor α (ER-α) causes a global increase in eRNA transcription on enhancers adjacent to E2-upregulated coding genes. These induced eRNAs, as functional transcripts, seem to exert important roles for the observed ligand-dependent induction of target coding genes, increasing the strength of specific enhancer-promoter looping initiated by ER-α binding. Cohesin, present on many ER-α-regulated enhancers even before ligand treatment, apparently contributes to E2-dependent gene activation, at least in part by stabilizing E2/ER-α/eRNA-induced enhancer-promoter looping. Our data indicate that eRNAs are likely to have important functions in many regulated programs of gene transcription.
    Nature 06/2013; · 38.60 Impact Factor
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    ABSTRACT: Rev-Erb-α and Rev-Erb-β are nuclear receptors that regulate the expression of genes involved in the control of circadian rhythm, metabolism and inflammatory responses. Rev-Erbs function as transcriptional repressors by recruiting nuclear receptor co-repressor (NCoR)-HDAC3 complexes to Rev-Erb response elements in enhancers and promoters of target genes, but the molecular basis for cell-specific programs of repression is not known. Here we present evidence that in mouse macrophages Rev-Erbs regulate target gene expression by inhibiting the functions of distal enhancers that are selected by macrophage-lineage-determining factors, thereby establishing a macrophage-specific program of repression. Remarkably, the repressive functions of Rev-Erbs are associated with their ability to inhibit the transcription of enhancer-derived RNAs (eRNAs). Furthermore, targeted degradation of eRNAs at two enhancers subject to negative regulation by Rev-Erbs resulted in reduced expression of nearby messenger RNAs, suggesting a direct role of these eRNAs in enhancer function. By precisely defining eRNA start sites using a modified form of global run-on sequencing that quantifies nascent 5' ends, we show that transfer of full enhancer activity to a target promoter requires both the sequences mediating transcription-factor binding and the specific sequences encoding the eRNA transcript. These studies provide evidence for a direct role of eRNAs in contributing to enhancer functions and suggest that Rev-Erbs act to suppress gene expression at a distance by repressing eRNA transcription.
    Nature 06/2013; · 38.60 Impact Factor
  • Lan Xie, Amy L Sullivan, Jana G Collier, Christopher K Glass
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    ABSTRACT: Serum response factor (SRF) is required for diverse aspects of development and homeostasis, but potential roles in the regulation of inflammation and immunity have not been systematically investigated. Here, we demonstrate that SRF is unexpectedly required for optimal responses of elicited peritoneal macrophages to type I interferons. Knockdown of SRF expression in these cells impairs induction of numerous interferon (IFN)-stimulated genes (ISGs) in response to zymosan, LPS, and poly I:C. This effect is primarily due to a defect in the ability of induced type I interferons to mediate secondary activation of ISGs. SRF does not appear to be required for expression of established components of the type I interferon signaling pathway, with IFN-β-dependent phosphorylation of STAT1 and STAT2 normally occurring in SRF-depleted macrophages. Collectively, these findings suggest that SRF can indirectly modulate type I interferon-signaling, without interfering with the classic JAK/STAT/ISGF3 pathway.
    Journal of interferon & cytokine research: the official journal of the International Society for Interferon and Cytokine Research 05/2013; · 1.63 Impact Factor
  • Ira Tabas, Christopher K Glass
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    ABSTRACT: A number of widespread and devastating chronic diseases, including atherosclerosis, type 2 diabetes, and Alzheimer's disease, have a pathophysiologically important inflammatory component. In these diseases, the precise identity of the inflammatory stimulus is often unknown and, if known, is difficult to remove. Thus, there is interest in therapeutically targeting the inflammatory response. Although there has been success with anti-inflammatory therapy in chronic diseases triggered by primary inflammation dysregulation or autoimmunity, there are considerable limitations. In particular, the inflammatory response is critical for survival. As a result, redundancy, compensatory pathways, and necessity narrow the risk:benefit ratio of anti-inflammatory drugs. However, new advances in understanding inflammatory signaling and its links to resolution pathways, together with new drug development, offer promise in this area of translational biomedical research.
    Science 01/2013; 339(6116):166-72. · 31.20 Impact Factor
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    ABSTRACT: Recent studies suggest that the sterol metabolic network participates in the interferon (IFN) antiviral response. However, the molecular mechanisms linking IFN with the sterol network and the identity of sterol mediators remain unknown. Here we report a cellular antiviral role for macrophage production of 25-hydroxycholesterol (cholest-5-en-3β,25-diol, 25HC) as a component of the sterol metabolic network linked to the IFN response via Stat1. By utilizing quantitative metabolome profiling of all naturally occurring oxysterols upon infection or IFN-stimulation, we reveal 25HC as the only macrophage-synthesized and -secreted oxysterol. We show that 25HC can act at multiple levels as a potent paracrine inhibitor of viral infection for a broad range of viruses. We also demonstrate, using transcriptional regulatory-network analyses, genetic interventions and chromatin immunoprecipitation experiments that Stat1 directly coupled Ch25h regulation to IFN in macrophages. Our studies describe a physiological role for 25HC as a sterol-lipid effector of an innate immune pathway.
    Immunity 12/2012; · 19.80 Impact Factor
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    ABSTRACT: Recent studies have identified a number of transcriptional regulators, including E2A, early B-cell factor 1 (EBF1), FOXO1, and paired box gene 5 (PAX5), that promote early B-cell development. However, how this ensemble of regulators mechanistically promotes B-cell fate remains poorly understood. Here we demonstrate that B-cell development in FOXO1-deficient mice is arrested in the common lymphoid progenitor (CLP) LY6D(+) cell stage. We demonstrate that this phenotype closely resembles the arrest in B-cell development observed in EBF1-deficient mice. Consistent with these observations, we find that the transcription signatures of FOXO1- and EBF1-deficient LY6D(+) progenitors are strikingly similar, indicating a common set of target genes. Furthermore, we found that depletion of EBF1 expression in LY6D(+) CLPs severely affects FOXO1 mRNA abundance, whereas depletion of FOXO1 activity in LY6D(+) CLPs ablates EBF1 transcript levels. We generated a global regulatory network from EBF1 and FOXO1 genome-wide transcription factor occupancy and transcription signatures derived from EBF1- and FOXO1-deficient CLPs. This analysis reveals that EBF1 and FOXO1 act in a positive feedback circuitry to promote and stabilize specification to the B-cell lineage.
    Proceedings of the National Academy of Sciences 12/2012; · 9.74 Impact Factor
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    ABSTRACT: Although liganded nuclear receptors have been established to regulate RNA polymerase II (Pol II)-dependent transcription units, their role in regulating Pol III-transcribed DNA repeats remains largely unknown. Here we report that ~2-3% of the ~100,000-200,000 total human DR2 Alu repeats located in proximity to activated Pol II transcription units are activated by the retinoic acid receptor (RAR) in human embryonic stem cells to generate Pol III-dependent RNAs. These transcripts are processed, initially in a DICER-dependent fashion, into small RNAs (~28-65 nt) referred to as repeat-induced RNAs that cause the degradation of a subset of crucial stem-cell mRNAs, including Nanog mRNA, which modulate exit from the proliferative stem-cell state. This regulation requires AGO3-dependent accumulation of processed DR2 Alu transcripts and the subsequent recruitment of AGO3-associated decapping complexes to the target mRNA. In this way, the RAR-dependent and Pol III-dependent DR2 Alu transcriptional events in stem cells functionally complement the Pol II-dependent neuronal transcriptional program.
    Nature Structural & Molecular Biology 10/2012; · 11.90 Impact Factor

Publication Stats

38k Citations
4,021.55 Total Impact Points


  • 1988–2014
    • University of California, San Diego
      • • Department of Cellular and Molecular Medicine (CMM)
      • • Department of Medicine
      San Diego, California, United States
  • 2013
    • Columbia University
      • Department of Medicine
      New York City, NY, United States
    • Tsinghua University
      • School of Medicine
      Beijing, Beijing Shi, China
  • 2011–2013
    • University of Eastern Finland
      • A.I. Virtanen Institute for Molecular Sciences
      Kuopio, Eastern Finland Province, Finland
    • University of California, Los Angeles
      • Division of Digestive Diseases
      Los Angeles, CA, United States
  • 1990–2013
    • Howard Hughes Medical Institute
      Maryland, United States
  • 1991–2012
    • Molecular and Cellular Biology Program
      • Department of Molecular Biology
      Seattle, Washington, United States
  • 2007–2010
    • Spanish National Centre for Cardiovascular Research
      • Department of Vascular Biology and Inflammation (BVI)
      Madrid, Madrid, Spain
    • San Diego Supercomputer Center
      La Jolla, California, United States
  • 1990–2010
    • National University (California)
      San Diego, California, United States
  • 2009
    • Saitama Medical University
      • Research Center for Genomic Medicine
      Saitama, Saitama-ken, Japan
  • 2000–2008
    • University of California, Riverside
      • Division of Biomedical Sciences
      Riverside, CA, United States
    • University of Naples Federico II
      Napoli, Campania, Italy
  • 2006
    • Duke University Medical Center
      • Department of Biochemistry
      Durham, NC, United States
  • 2005
    • Georgia Institute of Technology
      Atlanta, Georgia, United States
  • 2002
    • CSU Mentor
      Long Beach, California, United States
    • University of Vienna
      Wien, Vienna, Austria
  • 1999
    • University of South Florida
      Tampa, Florida, United States