Visualization of peptides derived from liposome-encapsulated proteins in the trans-Golgi area of macrophages

Rao, Mangala; Rothwell, Stephen W.; Wassef, Nabila M.; Pagano, Richard E.; Alving, Carl R.

doi:10.1016/s0165-2478(97)00107-7

Cited by 32 publications

(41 citation statements)

References 33 publications

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“…We have previously shown that liposomes (L) serve as an efficient delivery system for a variety of antigens and evoke both types of immune response (2,28,30). L-encapsulated protein and peptide antigens enter the major histocompatibility complex (MHC) class I pathway and thus are efficient inducers of cytotoxic T lymphocytes (CTLs) (2,(18)(19)(20)(21)23). It was previously shown that immunization of B10.BR mice with irradiated EBO-Z in L containing lipid A induced CTLs specific for EBO-Z GP peptides and that lipid A was necessary for a long-term CTL memory recall response (21).…”

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confidence: 99%

Induction of Immune Responses in Mice and Monkeys to Ebola Virus after Immunization with Liposome-Encapsulated Irradiated Ebola Virus: Protection in Mice Requires CD4 ⁺ T Cells

Rao

Bray²,

Alving

et al. 2002

J Virol

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confidence: 99%

Induction of Immune Responses in Mice and Monkeys to Ebola Virus after Immunization with Liposome-Encapsulated Irradiated Ebola Virus: Protection in Mice Requires CD4 ⁺ T Cells

Rao

Bray²,

Alving

et al. 2002

J Virol

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“…Macrophages and dendritic cells were cultured from the marrows of C57BL/6 mice as previously described (46,49). Dendritic cells were cultured in vitro with murine recombinant granulocyte-macrophage colony stimulating factor (0.1 mg/ ml) (BioSource, Invitrogen Corporation) and interleukin-4 (IL-4) (0.04 mg/ml) (BioSource).…”

Section: Methodsmentioning

confidence: 99%

Human Immunodeficiency Virus Type 1 Gag p24 Alters the Composition of Immunoproteasomes and Affects Antigen Presentation

Steers

Peachman

McClain

et al. 2009

J Virol

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Proteasomes are the major source of proteases responsible for the generation of peptides bound to major histocompatibility complex class I molecules. Antigens, adjuvants, and cytokines can modulate the composition and enzymatic activity of proteasomes and thus alter the epitopes generated. In the present study, we examined the effect of human immunodeficiency virus type 1 (HIV-1) p24 on proteasomes from a dendritic cell line (JAWS II), from a macrophage cell line (C2.3), and from murine primary bone marrow-derived macrophages and dendritic cells. HIV-1 p24 downregulated PA28␤ and the ␤2i subunit of the immunoproteasome complex in JAWS II cells but did not decrease the immunoproteasome subunits in macrophages, whereas in primary dendritic cells, PA28␣, ␤2i, and ␤5i were downregulated. Exposure of JAWS II cells and primary dendritic cells to HIV-1 p24 for 90 min significantly decreased the presentation of ovalbumin to a SIINFEKL-specific CD8 ؉ T-cell hybridoma. The decrease in antigen presentation and the downmodulation of the immunoproteasome subunits in JAWS II cells and primary dendritic cells could be overcome by pretreating the cells with gamma interferon for 6 h or by exposing the cells to HIV-1 p24 encapsulated in liposomes containing lipid A. These results suggest that early antigen processing kinetics could influence the immunogenicity of CD8 ؉ T-cell epitopes generated.Detection and elimination of cells infected with intracellular pathogens such as viruses or parasites are controlled by cytotoxic T lymphocytes (CTLs) that specifically recognize antigenic peptides (approximately 8 to 10 amino acids) bound to major histocompatibility complex (MHC) class I molecules on the surface of the cell (23,43,68,71). It is the interaction of the T-cell receptor and the peptide-bound MHC class I molecule that determines recognition of self or foreign peptide (17,27). Virtually all of the peptides bound to MHC class I molecules are derived from processing of endogenous proteins by the proteasome complex (22, 51). Peptides ranging between 2 and 25 amino acids in length are generated by the proteasome cleavage step (24,52,56,66). These peptides are further trimmed and transported across the membrane of the endoplasmic reticulum and the cis-Golgi apparatus in an ATPdependent manner by specific transporters associated with antigen processing (4, 40).A key component in MHC class I processing is the 26S multicatalytic proteasome complex, which is thought to be responsible for generating 95% of the peptides (32). The proteasome complex is barrel shaped and consists of a catalytic 20S core and two 19S regulatory complexes that bind and unfold ubiquinated proteins (31). The 20S core consists of four stacked rings, with each ring composed of seven subunits. The two outer rings consist of seven different but homologous ␣ subunits (␣1 to ␣7), which bind to the regulatory complexes of the core. The two inner rings consist of seven different ␤ subunits (␤1 to ␤7) (25). The active centers of the constitutive proteasomes (c20S; consti...

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“…More recently, it was suggested that internalized antigens move in a retrograde direction through the Golgi into the ER (Ackerman et al, 2005). Accumulation of particulate antigens has been observed in the trans-Golgi in macrophages and dendritic cells and this movement requires MTs (Rao et al, 1997;Peachman et al, 2004). Our findings support these latter studies and provide microscopic evidence for a close phagosome/Golgi interaction.…”

Section: E W Eng Et Almentioning

confidence: 99%

MTOC Reorientation Occurs during FcγR-mediated Phagocytosis in Macrophages

Eng

Bettio

Ibrahim

et al. 2007

MBoC

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Cell polarization is essential for targeting signaling elements and organelles to active plasma membrane regions. In a few specialized cell types, cell polarity is enhanced by reorientation of the MTOC and associated organelles toward dynamic membrane sites. Phagocytosis is a highly polarized process whereby particles >0.5 m are internalized at stimulated regions on the cell surface of macrophages. Here we provide detailed evidence that the MTOC reorients toward the site of particle internalization during phagocytosis. We visualized MTOC proximity to IgG-sRBCs in fixed RAW264.7 cells, during live cell imaging using fluorescent chimeras to label the MTOC and using frustrated phagocytosis assays. MTOC reorientation in macrophages is initiated by Fc␥R ligation and is complete within 1 h. Polarization of the MTOC toward the phagosome requires the MT cytoskeleton and dynein motor activity. cdc42, PI3K, and mPAR-6 are all important signaling molecules for MTOC reorientation during phagocytosis. MTOC reorientation was not essential for particle internalization or phagolysosome formation. However Golgi reorientation in concert with MTOC reorientation during phagocytosis implicates MTOC reorientation in antigen processing events in macrophages. INTRODUCTIONPhagocytosis is a specialized mechanism for cells of the innate immune system to clear pathogens and dying cells from the body. Phagocytosis is initiated at the site of particle/pathogen attachment, creating a polarized region of activity within the macrophage. This process is a rapid, highly orchestrated event that recruits a multitude of signaling proteins, mobilizes organelles, and causes dramatic cytoskeletal rearrangements. Phagocytosis is initiated by ligation of Fc␥ receptors to IgG-opsonins on the target cell. Engaged Fc␥Rs cluster at the site of particle contact, which in turn recruits Src, Syk, and PI3K (Greenberg and Grinstein, 2002). Local activation of cdc42 and rac1 initiates actin remodeling that coincides with the growth of membrane pseudopods (Greenberg and Grinstein, 2002). Within minutes, the particles are engulfed by the pseudopods into the cytoplasm as a membrane-bound phagosome. Particle contents within the phagosome are then degraded by fusion with the macrophage endocytic machinery. Phagolysosome formation is concomitant with retrograde translocation of the phagosome along the microtubule (MT) cytoskeleton (Blocker et al., 1997;Harrison and Grinstein, 2002;Harrison et al., 2003). Over the next several hours, particulate antigens from the phagosome will bind to specialized antigen-presentation proteins that will become displayed on the cell surface to initiate the adaptive immune response. Exogenous antigens bind to Major Histocompatibility Complex II (MHCII) proteins, which are largely delivered to phagosomes from Golgi-derived endocytic organelles (Ramachandra and Harding, 2000). Macrophages are also capable of cross-presenting antigens that become complexed with MHC I molecules in the endoplasmic reticulum (ER), before surface presentation (G...

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Visualization of peptides derived from liposome-encapsulated proteins in the trans-Golgi area of macrophages

Cited by 32 publications

References 33 publications

Induction of Immune Responses in Mice and Monkeys to Ebola Virus after Immunization with Liposome-Encapsulated Irradiated Ebola Virus: Protection in Mice Requires CD4 ⁺ T Cells

Induction of Immune Responses in Mice and Monkeys to Ebola Virus after Immunization with Liposome-Encapsulated Irradiated Ebola Virus: Protection in Mice Requires CD4 ⁺ T Cells

Human Immunodeficiency Virus Type 1 Gag p24 Alters the Composition of Immunoproteasomes and Affects Antigen Presentation

MTOC Reorientation Occurs during FcγR-mediated Phagocytosis in Macrophages

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Visualization of peptides derived from liposome-encapsulated proteins in the trans-Golgi area of macrophages

Cited by 32 publications

References 33 publications

Induction of Immune Responses in Mice and Monkeys to Ebola Virus after Immunization with Liposome-Encapsulated Irradiated Ebola Virus: Protection in Mice Requires CD4 + T Cells

Induction of Immune Responses in Mice and Monkeys to Ebola Virus after Immunization with Liposome-Encapsulated Irradiated Ebola Virus: Protection in Mice Requires CD4 + T Cells

Human Immunodeficiency Virus Type 1 Gag p24 Alters the Composition of Immunoproteasomes and Affects Antigen Presentation

MTOC Reorientation Occurs during FcγR-mediated Phagocytosis in Macrophages

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Induction of Immune Responses in Mice and Monkeys to Ebola Virus after Immunization with Liposome-Encapsulated Irradiated Ebola Virus: Protection in Mice Requires CD4 ⁺ T Cells

Induction of Immune Responses in Mice and Monkeys to Ebola Virus after Immunization with Liposome-Encapsulated Irradiated Ebola Virus: Protection in Mice Requires CD4 ⁺ T Cells