Disease relevance of Lnpep

• We show here that a single subcutaneous immunization in mice with immunostimulating complexes containing either purified intact gp160 envelope glycoprotein of the human immunodeficiency virus (HIV)-1 or influenza haemagglutinin results in reproducible and long-lasting priming of HIV specific or influenza-specific CD8+, MHC class I restricted CTL [1].
• We show that mucosal immunization of vaccinia-immune BALB/c mice with recombinant vaccinia expressing HIV gp160 induced specific serum antibody and strong HIV-specific cytotoxic T lymphocyte responses [2].
• In addition to the difference in the molecular weight of two of these antigens, gp160, S25, and gp120r can be distinguished on the basis of differential expression on a panel of cultured renal cancers and normal kidney epithelium and fetal kidney cells [3].
• Previous studies have shown that treatment of S91-C2 murine melanoma cells with beta-all-trans-retinoic acid (RA) results in growth inhibition, enhanced activity of sialyltransferase, and increased glycosylation of a Mr 160,000 cell surface sialoglycoprotein (gp160) [4].
• HIV-1 neutralizing antibodies in the genital and respiratory tracts of mice intranasally immunized with oligomeric gp160 [5].

High impact information on Lnpep

• T lymphocytes from mice and healthy humans immunized against the human immunodeficiency virus (HIV) envelope have recently been shown to recognize two antigenic regions of the gp160 HIV-envelope protein which have been located on the basis of amphipathicity [6].
• IL-2 and IL-15 were evaluated in vaccinia vectors expressing HIV gp160 for the establishment of an effective vaccine strategy [7].
• Spleen cells from vaccinia-infected control mice displayed strong CD8+ cytolytic activity against gp160-transfected fibroblasts and fibroblasts pulsed with a peptide (P18) representing a CTL epitope of gp160 [8].
• Interestingly, the NIH-PPAR gamma cells show normal insulin-dependent translocation of IRAP and form an insulin-responsive vesicular compartment as assessed by cell surface biotinylation and sucrose velocity gradient analysis, respectively [9].
• In parallel, microinjection of 18c/pep3 but not a control peptide inhibited the insulin-stimulated translocation of endogenous GLUT4 and insulin-responsive amino peptidase (IRAP) to the plasma membrane [10].

Chemical compound and disease context of Lnpep

• Taken together, our data support that inhibitors of proteolytic processing of gp160 may be useful for combating human immunodeficiency virus-1 and that polyarginine represents a lead example of such inhibitors [11].
• These particles packaged HIV genomic RNA and migrated to the same density as gp160-containing virions in a sucrose gradient [12].
• Adjuvanticity of stearyl tyrosine on the antibody response to peptide 503-535 from HIV gp160 [13].
• In contrast, HIV gp160 expression was lower in untreated or bupivacaine-treated muscles, but was improved by pretreatment with cardiotoxin [14].
• Archival, formalin-fixed, paraffin-embedded tissue blocks of 24 classical seminomas, 7 spermatocytic seminomas, and 20 non-seminomatous germ cell tumours were stained for 43-9F, AFP, hCG and PLAP expression [15].

Biological context of Lnpep

• We conclude that IRAP-/- mice maintain normal glucose homeostasis despite decreased glucose uptake into muscle and fat cells [16].
• HIV mucosal vaccine: nasal immunization with gp160-encapsulated hemagglutinating virus of Japan-liposome induces antigen-specific CTLs and neutralizing antibody responses [17].
• Three expression plasmids encoding HIV(Ba-L) gp160, cytoplasmic gp140, and secreted gp140 were tested in mice as protein sigma1-poly-L-lysine-DNA complexes (formulated vaccine) via the intranasal route [18].
• The enhanced immune response to the HIV gp160/LAMP chimeric gene product targeted to the lysosome membrane protein trafficking pathway [19].
• Evaluation of cell-mediated immunity showed that the formulated gp160 DNA vaccine was more effective for stimulating envelope (Env)-specific CTL responses in lungs, lower respiratory lymph nodes (LN), cervical LN, submaxillary gland LN, and spleens [18].

Anatomical context of Lnpep

• In this study we have characterized this aminopeptidase, referred to as vp165, in 3T3-L1 adipocytes [20].
• Insulin-regulated aminopeptidase (IRAP) is an abundant cargo protein of Glut4 storage vesicles (GSVs) that traffics to and from the plasma membrane in response to insulin [21].
• Basal and insulin-stimulated glucose uptake in extensor digitorum longus muscle, and adipocytes isolated from IRAP-/- mice were decreased by 30-60% but were normal for soleus muscle from male IRAP-/- mice [16].
• Thus, GLUT4 and IRAP content of early endosome-derived sorting vesicles and of IRVs are coordinately regulated, and both proteins are required for maintenance of key constituents of these compartments in cardiac muscle cells in vivo [22].
• MHC II-mediated T cell proliferation assays performed with cloned human cell lines showed that gp160/LAMP stimulated greater responses than did the wild type gp160 [19].

Associations of Lnpep with chemical compounds

• Whereas IRAP-/- mice responded to glucose administration like control mice, they exhibited an impaired response to insulin [16].
• In H-2d mice, the immunodominant determinant of the HIV-1-IIIB gp160 envelope glycoprotein recognized by CD8+ CTL is represented by a 15-residue synthetic peptide (315-329: RIQRGPGRAFVTIGK) [23].
• In this study, nasal immunization of mice with o-gp160, formulated with liposomes containing monophosphoryl lipid A (MPL), MPL-AF, proteosomes, emulsomes, or proteosomes with emulsomes elicited strong gp160-specific IgG and IgA responses in serum as well as vaginal, lung, and intestinal washes and fecal pellets [5].
• The precursor gp160 was then isolated by preparative polyacrylamide gel electrophoresis [24].
• Transmission electron microscopy images of late LPC-1 cells suggested an active protein synthesis which correlated with a more intense deposition of ruthenium red and an increasing amount of gp160 on the cell surface [25].

Regulatory relationships of Lnpep

• These data suggest that the amino terminus of IRAP interacts with a retention/sorting protein that also regulates the distribution of Glut4 in insulin-responsive cells [26].
• However, GLUT4 but not vp165 is additionally localised in the regulated secretory pathway in atrial cardiomyocytes [27].

Other interactions of Lnpep

• Our results show that GLUT4 overexpression or deficiency affects the amount of other GLUT4-vesicle proteins including IRAP and VAMP2 and that GLUT4 sequestration is saturable [28].
• A fusion protein containing only 28 amino acids from IRAP (GST-IRAP-(55-82)) was as effective in increasing cell surface Glut4 as stimulation with 100 nM insulin (44% versus 43%, respectively) [26].
• Both preparations also had comparable levels of secretory carrier membrane proteins and of aminopeptidase activity (gp160) [29].
• Immunoabsorption of intracellular vesicles with anticellugyrin antibodies revealed that IRAP content was reduced by 70% in both cellugyrin-positive and cellugyrin-negative vesicles [22].
• Nasal immunization of normal mice with HIVgp160-encapsulated hemagglutinating virus of Japan (HVJ)-liposome induced high titers of gp160-specific neutralizing IgG in serum and IgA in nasal wash, saliva, fecal extract, and vaginal wash, along with both Th1- and Th2-type responses [17].

Analytical, diagnostic and therapeutic context of Lnpep

• By immunofluorescence, p115 partially colocalizes with GLUT4 and IRAP in the perinuclear region of cultured fat cells [21].
• The subcellular distributions of vp165 and Glut4 were determined by immunoisolation of vesicles with antibodies against both proteins, by immunofluorescence, and by subcellular fractionation and immunoblotting [20].
• Microinjection into 3T3-L1 adipocytes of a glutathione S-transferase (GST) fusion protein containing the cytosolic portion of IRAP (GST-IRAP-(1-109)), resulted in translocation of Glut4 to the cell surface [26].
• Immunogold electron microscopy revealed that overexpression of GLUT4 in adipocytes increased the number of GLUT4 molecules per vesicle nearly 2-fold and the number of GLUT4 and IRAP-containing vesicles per cell 3-fold [28].
• Using sucrose gradient centrifugation and cell surface biotinylation, we found that IRAP content in 50-80S vesicles where GLUT4 vesicles normally sediment was markedly depleted in G4H-/- hearts, and the remaining IRAP was found in the heavy membrane fraction [22].

References