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1.  Knockout of G protein β5 impairs brain development and causes multiple neurologic abnormalities in mice 
Journal of neurochemistry  2011;119(3):544-554.
Gβ5 is a divergent member of the signal-transducing G protein β subunit family encoded by GNB5 and expressed principally in brain and neuronal tissue. Among heterotrimeric Gβ isoforms, Gβ5 is unique in its ability to heterodimerize with members of the R7 subfamily of the regulator of G protein signaling (RGS) proteins that contain G protein-γ like domains. Previous studies employing Gnb5 knockout (KO) mice have shown that Gβ5 is an essential stabilizer of such RGS proteins and regulates the deactivation of retinal phototransduction and the proper functioning of retinal bipolar cells. However, little is known of the function of Gβ5 in the brain outside the visual system. We show here that mice lacking Gβ5 have a markedly abnormal neurologic phenotype that includes impaired development, tiptoe-walking, motor learning and coordination deficiencies, and hyperactivity. We further show that Gβ5-deficient mice have abnormalities of neuronal development in cerebellum and hippocampus. We find that the expression of both mRNA and protein from multiple neuronal genes is dysregulated in Gnb5 KO mice. Taken together with previous observations from Gnb5 KO mice, our findings suggest a model in which Gβ5 regulates dendritic arborization and/or synapse formation during development, in part by effects on gene expression.
PMCID: PMC3192915  PMID: 21883221
guanine nucleotide-binding regulatory protein; regulator of G protein signaling; R7BP; Purkinje cell; dendrite; dentate gyrus; limbic cortex
2.  Chemokines control naive CD8+ T cell selection of optimal lymph node antigen presenting cells 
The Journal of Experimental Medicine  2011;208(12):2511-2524.
CCR5-binding chemokines produced in the draining lymph node after vaccinia virus infection guide naive CD8+ T cells toward DCs and away from the macrophage-rich zone, thereby facilitating optimal CD8+ T cell activation and cytokine production.
Naive antiviral CD8+ T cells are activated in the draining LN (DLN) by dendritic cells (DCs) presenting viral antigens. However, many viruses infect LN macrophages, which participate in initiation of innate immunity and B cell activation. To better understand how and why T cells select infected DCs rather than macrophages, we performed intravital microscopy and ex vivo analyses after infecting mice with vaccinia virus (VV), a large DNA virus that infects both LN macrophages and DCs. Although CD8+ T cells interact with both infected macrophages and DCs in the LN peripheral interfollicular region (PIR), DCs generate more frequent and stable interactions with T cells. VV infection induces rapid release of CCR5-binding chemokines in the LN, and administration of chemokine-neutralizing antibodies diminishes T cell activation by increasing T cell localization to macrophages in the macrophage-rich region (MRR) at the expense of PIR DCs. Similarly, DC ablation increases both T cell localization to the MRR and the duration of T cell–macrophage contacts, resulting in suboptimal T cell activation. Thus, virus-induced chemokines in DLNs enable antiviral CD8+ T cells to distinguish DCs from macrophages to optimize T cell priming.
PMCID: PMC3256957  PMID: 22042976
3.  Quantal formation of lentiviruses in cells: segregation of viral glycoproteins to lipid rafts that associate individually with HIV-1 Capsids 
Cell host & microbe  2008;3(5):285-292.
The viral ribonucleoprotein complex of human immunodeficiency virus-1 (HIV-1) associates with the viral Envelope (Env) to form infectious virions. While Env and Gag are known to migrate to lipid microdomains, their stoichiometry and specificity of interaction is not known. Here, we analyze the association of different viral glycoproteins, HIV Env and Ebola GP, with HIV-1 Gag protein co-expressed in the same cell. Though these two viral spikes were both expressed, each associated independently with Gag and gave rise to two distinct virion populations, each with a spike of a single type. Confocal imaging demonstrated that HIV Env89.6 and Ebola GP localized to distinct lipid raft microdomains within the same cell, where each associated with distinct Gag particles. Similar Env localization was observed in HIV-infected T cells, where ~14 percent of Env was associated with Gag during productive infection. Together, these data suggest that a single Gag complex associates “quantally” with an individual lipid raft microdomain to assemble functional virions during infection.
PMCID: PMC2998762  PMID: 18474355
4.  A cell number counting factor alters cell metabolism 
It is still not clear how organisms regulate the size of appendages or organs during development. During development, Dictyostelium discoideum cells form groups of ∼2 × 104 cells. The cells secrete a protein complex called counting factor (CF) that allows them to sense the local cell density. If there are too many cells in a group, as indicated by high extracellular concentrations of CF, the cells break up the group by decreasing cell-cell adhesion and increasing random cell motility. As a part of the signal transduction pathway, CF decreases the activity of glucose-6-phosphatase to decrease internal glucose levels. CF also decreases the levels of fructose-1,6-bisphosphate and increases the levels of glucose-6-phosphate and fructose-6-phosphate. In this report, we focus on how a secreted signal used to regulate the size of a group of cells regulates many basic aspects of cell metabolism, including the levels of pyruvate, lactate, and ATP, and oxygen consumption.
PMCID: PMC2734026  PMID: 19721869
Dictyostelium discoideum; size regulation; pyruvate; lactate; ATP; oxygen consumption
5.  Infection of Specific Dendritic Cells by CCR5-Tropic Human Immunodeficiency Virus Type 1 Promotes Cell-Mediated Transmission of Virus Resistant to Broadly Neutralizing Antibodies 
Journal of Virology  2004;78(21):11980-11987.
The tropism of human immunodeficiency virus type 1 for chemokine receptors plays an important role in the transmission of AIDS. Although CXCR4-tropic virus is more cytopathic for T cells, CCR5-tropic strains are transmitted more frequently in humans for reasons that are not understood. Phenotypically immature myeloid dendritic cells (mDCs) are preferentially infected by CCR5-tropic virus, in contrast to mature mDCs, which are not susceptible to infection but instead internalize virus into a protected intracellular compartment and enhance the infection of T cells. Here, we define a mechanism to explain preferential transmission of CCR5-tropic viruses based on their interaction with mDCs and sensitivity to neutralizing antibodies. Infected immature mDCs differentiated normally and were found to enhance CCR5-tropic but not CXCR4-tropic virus infection of T cells even in the continuous presence of neutralizing antibodies. Infectious synapses also formed normally in the presence of such antibodies. Infection of immature mDCs by CCR5-tropic virus can therefore establish a pool of infected cells that can efficiently transfer virus at the same time that they protect virus from antibody neutralization. This property of DCs may enhance infection, contribute to immune evasion, and could provide a selective advantage for CCR5-tropic virus transmission.
PMCID: PMC523246  PMID: 15479838
6.  pH-Dependent Entry of Severe Acute Respiratory Syndrome Coronavirus Is Mediated by the Spike Glycoprotein and Enhanced by Dendritic Cell Transfer through DC-SIGN 
Journal of Virology  2004;78(11):5642-5650.
The severe acute respiratory syndrome coronavirus (SARS-CoV) synthesizes several putative viral envelope proteins, including the spike (S), membrane (M), and small envelope (E) glycoproteins. Although these proteins likely are essential for viral replication, their specific roles in SARS-CoV entry have not been defined. In this report, we show that the SARS-CoV S glycoprotein mediates viral entry through pH-dependent endocytosis. Further, we define its cellular tropism and demonstrate that virus transmission occurs through cell-mediated transfer by dendritic cells. The S glycoprotein was used successfully to pseudotype replication-defective retroviral and lentiviral vectors that readily infected Vero cells as well as primary pulmonary and renal epithelial cells from human, nonhuman primate, and, to a lesser extent, feline species. The tropism of this reporter virus was similar to that of wild-type, replication-competent SARS-CoV, and binding of purified S to susceptible target cells was demonstrated by flow cytometry. Although myeloid dendritic cells were able to interact with S and to bind virus, these cells could not be infected by SARS-CoV. However, these cells were able to transfer the virus to susceptible target cells through a synapse-like structure. Both cell-mediated infection and direct infection were inhibited by anti-S antisera, indicating that strategies directed toward this gene product are likely to confer a therapeutic benefit for antiviral drugs or the development of a SARS vaccine.
PMCID: PMC415834  PMID: 15140961
7.  Treatment of Experimental (Trinitrobenzene Sulfonic Acid) Colitis by Intranasal Administration of Transforming Growth Factor (Tgf)-β1 Plasmid 
In this study, we show that a single intranasal dose of a plasmid encoding active transforming growth factor β1 (pCMV-TGF-β1) prevents the development of T helper cell type 1 (Th1)-mediated experimental colitis induced by the haptenating reagent, 2,4,6-trinitrobenzene sulfonic acid (TNBS). In addition, such plasmid administration abrogates TNBS colitis after it has been established, whereas, in contrast, intraperitoneal administration of rTGF-β1 protein does not have this effect. Intranasal pCMV-TGF-β1 administration leads to the expression of TGF-β1 mRNA in the intestinal lamina propria and spleen for 2 wk, as well as the appearance of TGF-β1–producing T cells and macrophages in these tissues, and is not associated with the appearances of fibrosis. These cells cause marked suppression of interleukin (IL)-12 and interferon (IFN)-γ production and enhancement of IL-10 production; in addition, they inhibit IL-12 receptor β2 (IL-12Rβ2) chain expression. Coadministration of anti–IL-10 at the time of pCMV-TGF-β1 administration prevents the enhancement of IL-10 production and reverses the suppression of IL-12 but not IFN-γ secretion. However, anti–IL-10 leads to increased tumor necrosis factor α production, especially in established colitis. Taken together, these studies show that TGF-β1 inhibition of a Th1-mediated colitis is due to: (a) suppression of IL-12 secretion by IL-10 induction and (b) inhibition of IL-12 signaling via downregulation of IL-12Rβ2 chain expression. In addition, TGF-β1 may also have an inhibitory effect on IFN-γ transcription.
PMCID: PMC1887715  PMID: 10880525
delivery; hapten; interferon γ; tumor necrosis factor α; β-galactosidase
8.  Training For Health Care 
Canadian Family Physician  1979;25:92-94.
As primary health care professionals, family physicians can be in the forefront of the emerging field of preventive health counselling. Thus far the emphasis has been on the screening and treatment of disease. Consideration of lifestyle factors like family communication, nutrition, exercise and degree of stress receive little attention.
This article describes a family practice which functions as a health maintenance program. The influence of the family practice residency on the concept formation is described, and the difficulties and challenge of putting the concepts into practice are shown.
PMCID: PMC2382771  PMID: 21301587

Results 1-8 (8)