Michel L Tremblay

McGill University, Montréal, Quebec, Canada

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Publications (189)1397.92 Total impact

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    ABSTRACT: Most of our knowledge on PTPs is derived from human pathologies and mouse knockout models. These models largely correlate well with human disease phenotypes, but can be ambiguous due to compensatory mechanisms introduced by paralogous genes. Here we present the analysis of the PTP complement of the fruit fly and the complementary view that PTP studies in Drosophila will accelerate our understanding of PTPs in physiological and pathological conditions. With only 44 PTP genes, Drosophila represents a streamlined version of the human complement. Our integrated analysis places the Drosophila PTPs into evolutionary and functional contexts, thereby providing a platform for the exploitation of the fly for PTP research and the transfer of knowledge onto other model systems. Copyright © 2015. Published by Elsevier B.V.
    FEBS Letters 03/2015; DOI:10.1016/j.febslet.2015.03.005 · 3.34 Impact Factor
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    ABSTRACT: The three PRL (phosphatases of regenerating liver) protein tyrosine phosphatases (PRL-1, -2 and -3) have been identified as key contributors to metastasis in several human cancers, yet the molecular basis of their pro-oncogenic property is unclear. Among the subfamily of PRL phosphatases, overexpression of PRL-2 in breast cancer cells has been shown to promote tumor growth by a mechanism that remains to be uncovered. Here we show that PRL-2 regulates intracellular magnesium levels by forming a functional heterodimer with the magnesium transporter CNNM3. We further reveal that CNNM3 is not a phosphorylated substrate of PRL-2, and that the interaction occurs through a loop unique to the CBS pair domains of CNNM3 that exists only in organisms having PRL orthologs. Supporting the role of PRL-2 in cellular magnesium transport is the observation that PRL-2 knockdown results in a substantial decrease of cellular magnesium influx. Furthermore, in PRL-2 knockout mice, serum magnesium levels were significantly elevated as compared with control animals, indicating a pivotal role for PRL-2 in regulating cellular magnesium homeostasis. Although the expression levels of CNNM3 remained unchanged after magnesium depletion of various cancer cell lines, the interaction between endogenous PRL-2 and CNNM3 was markedly increased. Importantly, xenograft tumor assays with CNNM3 and a mutant form that does not associate with PRL-2 confirm that CNNM3 is itself pro-oncogenic, and that the PRL-2/CNNM3 association is important for conferring transforming activities. This finding is further confirmed from data in human breast cancer tissues showing that CNNM3 levels correlate positively with both PRL-2 expression and the tumor proliferative index. In summary, we demonstrate that oncogenic PRL-2 controls tumor growth by modulating intracellular magnesium levels through binding with the CNNM3 magnesium transporter.Oncogene advance online publication, 17 March 2014; doi:10.1038/onc.2014.33.
    Oncogene 02/2015; 34(8):986-995. DOI:10.1038/onc.2014.33 · 8.56 Impact Factor
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    ABSTRACT: Calnexin is a type I integral endoplasmic reticulum (ER) membrane protein, molecular chaperone, and a component of the translocon. We discovered a novel interaction between the calnexin cytoplasmic domain and UBC9, a SUMOylation E2 ligase, which modified the calnexin cytoplasmic domain by the addition of SUMO. We demonstrated that calnexin's interaction with the SUMOylation machinery modulates an interaction with protein tyrosine phosphatase 1B (PTP1B), an ER-associated protein tyrosine phosphatase involved in the negative regulation of insulin and leptin signaling. We showed that calnexin and PTP1B form UBC9-dependent complexes, revealing a previously unrecognized contribution of calnexin to the retention of PTP1B at the ER membrane. This work shows that the SUMOylation machinery links two ER proteins from divergent pathways to potentially affect cellular protein quality control and energy metabolism. Copyright © 2015, The American Society for Biochemistry and Molecular Biology.
    Journal of Biological Chemistry 01/2015; DOI:10.1074/jbc.M114.635474 · 4.60 Impact Factor
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    ABSTRACT: Obesity is a global epidemic resulting from increased energy intake, which alters energy homeostasis and results in an imbalance in fat storage and breakdown. G0/G1 switch gene 2 (G0s2) has been recently characterised in vitro as an inhibitor of adipose triglyceride lipase (ATGL), the rate-limiting step in fat catabolism. In the current study we aim to functionally characterise G0s2 within the physiological context of a mouse model.
    Diabetologia 11/2014; DOI:10.1007/s00125-014-3429-z · 6.88 Impact Factor
  • Experimental Hematology 08/2014; 42(8S):S37. DOI:10.1016/j.exphem.2014.07.136 · 2.81 Impact Factor
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    ABSTRACT: Patients with mutations in MMACHC have the autosomal recessive disease of cobalamin metabolism known as cblC. These patients are unable to convert cobalamin into the two active forms, methylcobalamin and adenosylcobalamin and consequently have elevated homocysteine and methylmalonic acid in blood and urine. In addition, some cblC patients have structural abnormalities, including congenital heart defects. Mmachc is conserved in the mouse and shows tissue and stage-specific expression pattern in midgestation stage embryos. To create a mouse model of cblC we generated a line of mice with a gene-trap insertion in intron 1 of the Mmachc gene, (MmachcGt(AZ0348)Wtsi). Heterozygous mice show a 50% reduction of MMACHC protein, and have significantly higher levels of homocysteine and methylmalonic acid in their blood. The MmachcGt allele was inherited with a transmission ratio distortion in matings with heterozygous animals. Furthermore, homozygous MmachcGt embryos were not found after embryonic day 3.5 and these embryos were unable to generate giant cells in outgrowth assays. Our findings confirm that cblC is modeled in mice with reduced levels of Mmachc and suggest an early requirement for Mmachc in mouse development.
    Molecular Genetics and Metabolism 07/2014; DOI:10.1016/j.ymgme.2014.05.002 · 2.83 Impact Factor
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    ABSTRACT: Both pro- and anti-inflammatory cytokines activate the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway; however, they elicit distinct transcriptional programs. Posttranslational modifications of STAT proteins, such as tyrosine phosphorylation, are critical to ensure the differential expression of STAT target genes. Although JAK-STAT signaling is dependent on reversible tyrosine phosphorylation, whether phosphatases contribute to the specificity of STAT-dependent gene expression is unclear. We examined the role of protein tyrosine phosphatase 1B (PTP1B) in regulating the interleukin-10 (IL-10)-dependent, STAT3-mediated anti-inflammatory response. We found that IL-10-dependent STAT3 phosphorylation and anti-inflammatory gene expression were enhanced in macrophages from PTP1B(-/-) mice compared to those in macrophages from wild-type mice. Consistent with this finding, the IL-10-dependent suppression of lipopolysaccharide-induced macrophage activation was increased in PTP1B(-/-) macrophages compared to that in wild-type macrophages, as was the IL-10-dependent increase in the cell surface expression of the anti-inflammatory cytokine receptor IL-4Rα. Furthermore, RNA sequencing revealed the expression of genes encoding proinflammatory factors in IL-10-treated PTP1B(-/-) macrophages, which correlated with increased phosphorylation of STAT1, which is not normally highly activated in response to IL-10. These findings identify PTP1B as a central regulator of IL-10R-STAT3 and IL-10R-STAT1 signaling, and demonstrate that phosphatases can tailor the quantitative and qualitative properties of cytokine-induced transcriptional responses.
    Science Signaling 05/2014; 7(324):ra43. DOI:10.1126/scisignal.2005020 · 7.65 Impact Factor
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    ABSTRACT: CD45 is a receptor-like member of the protein tyrosine phosphatase (PTP) family. We screened in silico for small molecules binding at a predicted allosteric pocket unique to the CD45 intracellular domain, and validated inhibitors by in vitro phosphatase assays. One compound 211 exhibited CD45 IC50 200 nM and had >100-fold selectivity over six related PTPs. The relevance of the allosteric pocket was verified through site directed mutagenesis. Compound 211 has a non-competitive mechanism of action, and it is extremely effective at preventing dephosphorylation of substrate Lck pY-505 versus preventing dephosphorylation of Lck pY-394. In cultured primary T cells, 211 prevents T-cell receptor-mediated activation of Lck, Zap-70 and MAPK, and IL-2 production. In a delayed-type hypersensitivity reaction in vivo, compound 211 abolished inflammation. This work demonstrates a novel approach to develop effective allosteric inhibitors that can be expanded to target the corresponding allosteric domains of other receptor PTPs.
    Molecular pharmacology 01/2014; 85(4). DOI:10.1124/mol.113.089847 · 4.12 Impact Factor
  • Matthew Feldhammer, Michel L Tremblay
    Methods 01/2014; 65(2):155. DOI:10.1016/j.ymeth.2014.01.011 · 3.22 Impact Factor
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    ABSTRACT: The 20q13 chromosomal region has been previously identified as the hereditary prostate cancer genetic-susceptibility locus on chromosome 20 (HPC20). In this study, the 20q13 region was shown to be frequently co-amplified with the androgen receptor (AR) in metastatic prostate cancer. Furthermore, the AR signaling axis, which plays an essential role in the pathogenesis of prostate cancer, was demonstrated to be central to the regulation of the 20q13 common amplified region (CAR). High-resolution mapping analyses revealed hot spots of AR recruitment to response elements in the vicinity of most genes located on the 20q13 CAR. Moreover, amplification of AR significantly co-occurred with CAR amplification on 20q13 and it was confirmed that the majority of AR-bound genes on the 20q13 CAR were indeed regulated by androgens. These data reveal that amplification of the AR is tightly linked to amplification of the AR-regulated CAR region on 20q13. These results suggest that the cross-talk between gene amplification and gene transcription is an important step in the development of castration-resistant metastatic disease. *MLT and LCT are co-corresponding authors
    Molecular Cancer Research 12/2013; 12(2):184-189. DOI:10.1158/1541-7786.MCR-13-0477 · 4.50 Impact Factor
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    ABSTRACT: For years, the two main isoforms of PTPN2 have been an interesting yet academic topic of debate for researchers working on this phosphatase. In recent years, several studies were published in which these isoforms were attributed specific functions. Most importantly, differences in their stoichiometry have been reported to be associated with certain diseases such as inflammatory bowel diseases (IBDs). Hence, understanding the evolutionary ontogeny of the main transcripts and the physiological consequences of their expression have now become clinically relevant issues. Herein we describe the genomic controls placed upon PTPN2, the identified splice variants, the encoded PTPN2 proteins, and both the known and putative post-translational modifications that have been reported. Moreover, we examine the expression of PTPN2 isoforms in specific tissues as well as in a disease setting. PTPN2 is an important negative regulator of inflammation. Therefore, the following protocols are effective approaches for its adequate monitoring in inflammatory diseases' progression and outcome.
    Methods 08/2013; DOI:10.1016/j.ymeth.2013.08.020 · 3.22 Impact Factor
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    Michel L Tremblay
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    ABSTRACT: The increasing importance of signal transducer and activator of transcription 3 (STAT3) expression in human cancers has led several laboratories to examine in detail the expression of one of its major negative regulators in oncogenesis - the T-cell protein tyrosine phosphatase, nonreceptor type32 (PTPN2). A recent paper by Shields and colleagues points to the associate depletion of PTPN2 in STAT3-positive breast cancers. We examine these findings and reflect on the mechanism of action of PTPN2 and the consequences of its modulation for STAT3 downstream signaling.
    Breast cancer research: BCR 07/2013; 15(4):312. DOI:10.1186/bcr3437 · 5.88 Impact Factor
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    ABSTRACT: Reversible tyrosine phosphorylation is a fundamental signaling mechanism controlling a diversity of cellular processes. Whereas protein tyrosine kinases have long been implicated in many diseases, aberrant protein tyrosine phosphatase (PTP) activity is increasingly being associated with a wide spectrum of conditions too. PTPs are now regarded as key regulators of biochemical processes instead of simple "off" switches operating in tyrosine kinase signaling pathways. Despite the central importance that PTPs play in the cell's biochemistry, the tyrosine phosphatomes of most species remain uncharted. Here we present a highly sensitive and specific sequence-based method for the automatic classification of PTPs. As proof of principle we re-annotated the human tyrosine phosphatome, and discovered four new PTP genes that had not been reported before. Our method and the predicted tyrosine phosphatomes of 65 eukaryotic genomes are accessible online through the user-friendly PTP-central resource (http://www.PTP-central.org/), where users can also submit their own sequences for prediction. PTP-central is a comprehensive and continually developing resource that currently integrates the predicted tyrosine phosphatomes with structural data and genetic association disease studies, as well as homology relationships. PTP-central thus fills an important void for the systematic study of PTPs, both in model organisms and from an evolutionary perspective.
    Methods 07/2013; DOI:10.1016/j.ymeth.2013.07.031 · 3.22 Impact Factor
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    ABSTRACT: PTP-PEST is a cytosolic ubiquitous protein tyrosine phosphatase (PTP) that contains, in addition to its catalytic domain, several protein-protein interaction domains that allow it to interface with several signaling pathways. Among others, PTP-PEST is a key regulator of cellular motility and cytoskeleton dynamics. The complexity of the PTP-PEST interactome underscores the necessity to identify its interacting partners and physiological substrates in order to further understand its role in focal adhesion complex turnover and actin organization. Using a modified yeast substrate trapping two-hybrid system, we identified a cytosolic adaptor protein named Src Kinase Associated Phosphoprotein 55 Homologue (SKAP-Hom) as a novel substrate of PTP-PEST. In order to confirm PTP-PEST interaction with SKAP-Hom, in vitro pull down assays were performed demonstrating that the PTP catalytic domain and Proline-rich 1 (P1) domain are respectively binding to the SKAP-Hom Y260 and Y297 residues and its SH3 domain. Subsequently, we generated and rescued SKAP-Hom deficient mouse embryonic fibroblasts (MEFs) with WT SKAP-Hom, SKAP-Hom tyrosine mutants (Y260F, Y260F/Y297F), or SKAP-Hom SH3 domain mutant (W335K). Given the role of PTP-PEST, wound-healing and trans-well migration assays were performed using the generated lines. Indeed, SKAP-Hom deficient MEFs showed a defect in migration compared to WT-rescued MEFs. Interestingly, the SH3 domain mutant-rescued MEFs showed an enhanced cell migration corresponding potentially with higher tyrosine phosphorylation levels of SKAP-Hom. These findings suggest a novel role of SKAP-Hom and its phosphorylation in the regulation of cellular motility. Moreover, these results open new avenues by which PTP-PEST regulates cellular migration, a hallmark of metastasis.
    Journal of Biological Chemistry 07/2013; 288(36). DOI:10.1074/jbc.M113.501007 · 4.60 Impact Factor
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    ABSTRACT: Abstract Our understanding of the fundamental regulatory roles that tyrosine phosphatases play within cells has advanced significantly in the last two decades. Out-dated ideas that tyrosine phosphatases acts solely as the "off" switch counterbalancing the action of tyrosine kinases has proved to be flawed. PTP1B is the most characterized of all the tyrosine phosphatases and it acts as a critical negative and positive regulator of numerous signaling cascades. PTP1B's direct regulation of the insulin and the leptin receptors makes it an ideal therapeutic target for type II diabetes and obesity. Moreover, the last decade has also seen several reports establishing PTP1B as key player in cancer serving as both tumor suppressor and tumor promoter depending on the cellular context. Despite many key advances in these fields one largely ignored area is what role PTP1B may play in the modulation of immune signaling. The important recognition that PTP1B is a major negative regulator of Janus kinase - signal transducer and activator of transcription (JAK-STAT) signaling throughout evolution places it as a key link between metabolic diseases and inflammation, as well as a unique regulator between immune response and cancer. This review looks at the emergence of PTP1B through evolution, and then explore at the cell and systemic levels how it is controlled physiologically. The second half of the review will focus on the role(s) PTP1B can play in disease and in particular its involvement in metabolic syndromes and cancer. Finally we will briefly examine several novel directions in the development of PTP1B pharmacological inhibitors.
    Critical Reviews in Biochemistry and Molecular Biology 07/2013; DOI:10.3109/10409238.2013.819830 · 5.58 Impact Factor
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    ABSTRACT: Leukocyte antigen related (LAR) family receptor protein tyrosine phosphatases (RPTPs) regulate the fine balance between tyrosine phosphorylation and dephosphorylation that is crucial for cell signaling during development and tissue homeostasis. Here we show that LAR RPTPs are required for normal development of the mandibular and maxillary regions. Approximately half of the mouse embryos lacking both Ptprs (RPTPσ) and Ptprf (LAR) exhibit micrognathia (small lower jaw), cleft palate and microglossia/glossoptosis (small and deep tongue), a phenotype closely resembling Pierre-Robin sequence in humans. We show that jaw bone and cartilage patterning occurs aberrantly in LAR family phosphatase-deficient embryos and that the mandibular arch harbors a marked decrease in cell proliferation. Analysis of signal transduction in embryonic tissues and mouse embryonic fibroblast cultures identifies an increase in Bmp-Smad signaling and an abrogation of canonical Wnt signaling associated with loss of the LAR family phosphatases. A reactivation of β-catenin signaling by chemical inhibition of GSK3β successfully resensitizes LAR family phosphatase-deficient cells to Wnt induction, indicating that RPTPs are necessary for normal Wnt/β-catenin pathway activation. Together these results identify LAR RPTPs as important regulators of craniofacial morphogenesis and provide insight into the etiology of Pierre-Robin sequence.
    Development 07/2013; 140(16). DOI:10.1242/dev.094532 · 6.27 Impact Factor
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    ABSTRACT: A screen of a library of diverse small-molecules against a subset of phosphatases identified 7b and 7c, which potently inhibit TC-PTP, PTPσ and PTP1B with no inhibition of PTP-LAR, PRL2 A/S, MKPX or papain. In CHO-IR cells these inhibitors effectively suppress PTP1B activity restoring the insulin receptor phosphorylation levels.
    Medicinal Chemistry Communication 05/2013; 4(6):987-992. DOI:10.1039/C3MD00011G · 2.63 Impact Factor
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    ABSTRACT: Myeloid leukemia factor 1-interacting protein (MLF1-IP) has been found to exert functions in mitosis, although studies have been conducted only in cell lines up to now. To understand its roles during ontogeny and immunity, we analyzed its mRNA expression pattern by in situ hybridization and generated MLF1-IP gene knockout (KO) mice. MLF1-IP was expressed at elevated levels in most rudimentary tissues during the mid-gestation stage, between embryonic day 9.5 (e9.5) and e15.5. It declined afterwards in these tissues, but was very high in the testes and ovaries in adulthood. At post-natal day 10 (p10), the retina and cerebellum still expressed moderate MLF1-IP levels, although these tissues do not contain fast-proliferating cells at this stage. MLF1-IP expression in lymphoid organs, such as the thymus, lymph nodes, spleen and bone marrow, was high between e15.5 and p10, and decreased in adulthood. MLF1-IP KO embryos failed to develop beyond e6.5. On the other hand, MLF1-IP(+/-) mice were alive and fertile, with no obvious anomalies. Lymphoid organ size, weight, cellularity and cell sub-populations in MLF1-IP(+/-) mice were in the normal range. The functions of MLF1-IP(+/-) T cells and naïve CD4 cells, in terms of TCR-stimulated proliferation and Th1, Th17 and Treg cell differentiation in vitro, were comparable to those of wild type T cells. Our study demonstrates that MLF1-IP performs unique functions during mouse embryonic development, particularly around e6.5, when there was degeneration of epiblasts. However, the cells could proliferate dozens of rounds without MLF1-IP. MLF1-IP expression at about 50% of its normal level is sufficient to sustain mice life and the development of their immune system without apparent abnormalities. Our results also raise an intriguing question that MLF1-IP might have additional functions unrelated to cell proliferation.
    PLoS ONE 05/2013; 8(5):e63783. DOI:10.1371/journal.pone.0063783 · 3.53 Impact Factor
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    ABSTRACT: The clinical application of hematopoietic progenitor cell-based therapies for the treatment of hematological diseases is hindered by current protocols, which are cumbersome and have limited efficacy to augment the progenitor cell pool. We report that inhibition of T cell protein tyrosine phosphatase (TC-PTP), an enzyme involved in the regulation of cytokine signaling, through gene knockout results in a 9-fold increase in the number of hematopoietic progenitors in murine bone marrow (BM). This effect could be reproduced using a short (48 h) treatment with a pharmacological inhibitor of TC-PTP in murine BM, as well as in human BM, peripheral blood and cord blood. We also demonstrate that the ex-vivo use of TC-PTP inhibitor only provides a temporary effect on stem cells and did not alter their capacity to reconstitute all hematopoietic components in vivo. We establish that one of the mechanisms whereby inhibition of TC-PTP mediates its effects involves the IL-18 signaling pathway, leading to increased production of IL-12 and IFN-γ by progenitor cells. Together, our results reveal a previously unrecognized role for IL-18 in contributing to the augmentation of the stem cell pool, and provide a novel and simple method to rapidly expand progenitor cells from a variety of sources using a pharmacological compound.
    Stem Cells 02/2013; 31(2). DOI:10.1002/stem.1276 · 7.70 Impact Factor
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    ABSTRACT: Transcription factors (TFs) regulate gene expression by binding to short DNA sequence motifs, yet their binding specificities alone cannot explain how certain TFs drive a diversity of biological processes. In order to investigate the factors that control the functions of the pleiotropic TF STAT3, we studied its genome-wide binding patterns in four different cell types: embryonic stem cells, CD4(+) T cells, macrophages and AtT-20 cells. We describe for the first time two distinct modes of STAT3 binding. First, a small cell type-independent mode represented by a set of 35 evolutionarily conserved STAT3-binding sites that collectively regulate STAT3's own functions and cell growth. We show that STAT3 is recruited to sites with E2F1 already pre-bound before STAT3 activation. Second, a series of different transcriptional regulatory modules (TRMs) assemble around STAT3 to drive distinct transcriptional programs in the four cell types. These modules recognize cell type-specific binding sites and are associated with factors particular to each cell type. Our study illustrates the versatility of STAT3 to regulate both universal- and cell type-specific functions by means of distinct TRMs, a mechanism that might be common to other pleiotropic TFs.
    Nucleic Acids Research 01/2013; DOI:10.1093/nar/gks1300 · 8.81 Impact Factor

Publication Stats

10k Citations
1,397.92 Total Impact Points

Institutions

  • 1995–2015
    • McGill University
      • • Department of Biochemistry
      • • Division of Experimental Medicine
      Montréal, Quebec, Canada
  • 2013
    • University of Toronto
      • Department of Immunology
      Toronto, Ontario, Canada
  • 2005–2011
    • Monash University (Australia)
      • Department of Biochemistry and Molecular Biology
      Melbourne, Victoria, Australia
  • 2008
    • Université de Montréal
      Montréal, Quebec, Canada
  • 2007
    • Academia Sinica
      • Institute of Biological Chemistry
      T’ai-pei, Taipei, Taiwan
  • 2006
    • Fred Hutchinson Cancer Research Center
      • Division of Basic Sciences
      Seattle, Washington, United States
  • 2004
    • McGill University Health Centre
      Montréal, Quebec, Canada
    • Instituto de Investigación Clínica de Occidente
      Zapopan, Jalisco, Mexico
    • Friedrich-Schiller-University Jena
      • Institute of Molecular Cell Biology
      Jena, Thuringia, Germany
  • 2003
    • Cornell University
      • Department of Animal Science
      Ithaca, New York, United States
  • 2002
    • University of Western Australia
      Perth City, Western Australia, Australia
    • Institut de recherches cliniques de Montréal
      Montréal, Quebec, Canada
  • 1992–1994
    • National Institute of Child Health and Human Development
      Maryland, United States