A5038691946- Cellular transport and secretion
- Phagocytosis and Immune Regulation
- Bone Metabolism and Diseases
- Cell Adhesion Molecules Research
- Microtubule and mitosis dynamics
- Complement system in diseases
- Glycosylation and Glycoproteins Research
- Immune Response and Inflammation
- Proteoglycans and glycosaminoglycans research
- Cellular Mechanics and Interactions
- Monoclonal and Polyclonal Antibodies Research
- Immune cells in cancer
- Lipid Membrane Structure and Behavior
- Spaceflight effects on biology
- Erythrocyte Function and Pathophysiology
- Bone health and osteoporosis research
- Adenosine and Purinergic Signaling
- Endoplasmic Reticulum Stress and Disease
- Bone health and treatments
- Reproductive tract infections research
- Protease and Inhibitor Mechanisms
- Immunotherapy and Immune Responses
- Bone and Dental Protein Studies
- T-cell and B-cell Immunology
- Genetics, Aging, and Longevity in Model Organisms
University of Toronto
2015-2025
The Scarborough Hospital
2011-2024
Hospital for Sick Children
1998-2023
SickKids Foundation
2003-2004
University of Manitoba
1997
Children's Hospital of Philadelphia
1996
Nascent phagosomes must undergo a series of fusion and fission reactions to acquire the microbicidal properties required for innate immune response. Here we demonstrate that this maturation process involves GTPase Rab7. Rab7 recruitment was found precede be essential their with late endosomes and/or lysosomes. Active on phagosomal membrane associates effector protein RILP (Rab7-interacting lysosomal protein), which in turn bridges dynein-dynactin, microtubule-associated motor complex. The...
Phagosomal biogenesis is central for microbial killing and antigen presentation by leukocytes. However, the molecular mechanisms governing phagosome maturation are poorly understood. We analyzed role site of action phosphatidylinositol 3-kinases (PI3K) Rab GTPases in using both professional engineered phagocytes. Rab5, which recruited rapidly transiently to phagosome, was found be essential recruitment Rab7 progression phagolysosomes. Similarly, functional PI3K required successful...
We have identified two RHAMM (receptor for hyaluronan-mediated motility) isoforms that encode an alternatively spliced exon 4 (Hall, C. L., Yang, B., X., Zhang, S., Turley, M., Samuel, Lange, L. A., Wang, C., Curpen, G. D., Savani, R. Greenberg, A. H., and E. (1995) Cell 82, 19–26 Entwistle, J., Hou, G., Li, Q., (1996) Gene 174, 299–306). One of these, variant (RHAMMv4), is transforming when overexpressed regulates Ras signaling (Hall et al.). Here we note using flow cytometry confocal...
Binding of ligands by immunoreceptors is thought to be a passive, stochastic process. Contrary this notion, we found that binding IgG-opsonized particles Fcγ receptors was inhibited in macrophages, dendritic and microglial cells agents interfere with actin assembly or disassembly. Changes the lateral mobility receptors—assessed single-particle tracking—or microelasticity membrane—determined atomic-force microscopy—could not account for effects disruption on particle binding. Instead,...
As major effector cells of the innate immune response, macrophages must adeptly migrate from blood to infected tissues. Endothelial transmigration is accomplished by matrix metalloproteinase (MMP)-induced degradation basement membrane and extracellular components. The classical activation with LPS IFN-γ causes enhanced microtubule (MT) stabilization secretion MMPs. Macrophages up-regulate MMP-9 expression upon immunological challenge require its activity for migration during inflammatory...
After invasion of epithelial cells, Salmonella enterica Typhimurium resides within membrane-bound vacuoles where it survives and replicates. Like endocytic vesicles, the Salmonella-containing (SCVs) undergo a maturation process that involves sequential acquisition Rab5 Rab7 displacement toward microtubule-organizing center. However, SCVs fail to merge with lysosomes instead develop subsequently into filamentous network extends cell periphery. We found initial centripetal SCV is due...
A widespread belief in phagocyte biology is that FcγR-mediated phagocytosis utilizes membrane pseudopods, whereas Mac-1–mediated does not involve elaborate plasma extensions. Here we report dynamic ruffles activated macrophages promote binding of C3bi-opsonized particles. We identify these as components the macropinocytosis machinery both PMA- and LPS-stimulated macrophages. C3bi-particle capture facilitated by enrichment high-affinity Mac-1 integrin-regulating protein talin ruffles....
Macrophages are professional phagocytes that uniquely situated between the innate and adaptive arms of immunity with a high capacity for phagocytosis proinflammatory cytokine production as well antigen presentation. Phagocytosis is critical process to eliminate microbes, apoptotic cells other foreign particles accelerated by host-generated opsonins, such antibodies complement. Early studies established paradigm FcγR-mediated was more than Complement Receptor (CR)-mediated uptake in...
Functional interactions between Fcgamma-receptors (FcgammaR) and the beta2 integrin Mac-1 (CD11b/CD18) have been described, but molecular basis of this relationship remains unclear. Although glycosylphosphatidylinositol-linked receptor FcgammaRIIIB human neutrophils is constitutively associated with Mac-1, we found no evidence for direct physical association FcgammaR mouse macrophages, which are transmembrane proteins. Nevertheless, accumulated in phagocytic cup following engagement by...
Mutations in the gene coding for chloride channel ClC-5 cause Dent's disease, a disease associated with proteinuria and renal stones. Studies knockout mice suggest that this phenotype is related to defective endocytosis of low molecular weight proteins membrane by proximal tubule. In study, confocal micrographs tubules cultured epithelial cells revealed protein ClC-4 expressed endosomal membranes suggesting may also contribute function organelle. support hypothesis, specific disruption...
The obligate intracellular parasite Toxoplasma gondii exploits cells of the immune system to disseminate. Upon infection, parasitized dendritic (DCs) and microglia exhibit a hypermigratory phenotype in vitro that has been associated with enhancing dissemination vivo mice. One unresolved question is how parasites commandeer achieve systemic by 'Trojan-horse' mechanism. By chromatography mass spectrometry analyses, we identified an orthologue 14-3-3 protein family, T. (Tg14-3-3), as mediator...
Pathogenic mycobacteria survive within macrophages by precluding the fusion of phagosomes with late endosomes or lysosomes. Because molecular determinants normal phagolysosome formation are poorly understood, sites targeted remain unidentified. We found that Hrs, an adaptor molecule involved in protein sorting, associates prior to their Recruitment Hrs required interaction its FYVE domain phagosomal phosphatidylinositol 3-phosphate, but two other attachment were additionally involved....
Abstract Objective To compare the osteoclastogenic capacity of peripheral blood mononuclear cells (PBMCs) from patients with osteoarthritis (OA) to that PBMCs self‐reported normal individuals. Methods 140 OA and 45 healthy donors were assayed for CD14+ expression induced differentiate into osteoclasts over 3 weeks in vitro. We assessed number osteoclasts, their resorptive activity, osteoclast apoptosis, following cytokine receptors: RANK, interleukin‐1 receptor type I (IL‐1RI), IL‐1RII. A...
Abstract Phagocytosis is a complex sequence of events involving coordinated remodeling the plasma membrane with underlying cytoskeleton. Although role actin cytoskeleton becoming increasingly elucidated, microtubules (MTs) remains poorly understood. Here, we examine MTs during FcγR-mediated phagocytosis in RAW264.7 mouse macrophages. We observe that extend into phagosomal cups. The MT-depolymerizing agents, colchicine and nocodazole, cause sizeable reduction large particles cells. primed...
Classical activation of macrophages induces a wide range signaling and vesicle trafficking events to produce more aggressive cellular phenotype. The microtubule (MT) cytoskeleton is crucial for the regulation immune responses. In current study, we used large scale proteomics approach analyze change in protein composition MT-associated (MAP) network by macrophage stimulation with inflammatory cytokine interferon-gamma endotoxin lipopolysaccharide. Overall analysis identified 409 proteins that...
Abstract Macrophages can suppress Chlamydia replication by targeting the bacteria to degradative organelles such as lysosomes. trachomatis is an obligate intracellular bacterium responsible for one of most common sexually transmitted diseases. In epithelial cells, C. resides in a modified membrane-bound vacuole known inclusion, which isolated from endocytic pathway. However, maturation process within immune macrophages, has not been studied extensively. Here, we demonstrated that RAW...
Macrophages are generated through the differentiation of monocytes in tissues and they have important functions innate adaptive immunity. In addition to their roles as phagocytes, macrophages can be further differentiated, presence receptor activator nuclear factor kappa-B ligand (RANKL) macrophage colony-stimulating (M-CSF), into osteoclasts (multinucleated giant cells that responsible for bone resorption). this work, we set out characterize whether various inflammatory stimuli, known...