Reduced Cell Surface Expression of a Mutated Dipeptidyl Peptidase IV (DPP IV/CD26) Correlates with the Generation of a β Strand in Its C-Terminal Domain

1996 ◽  
Vol 222 (3) ◽  
pp. 833-838 ◽  
Author(s):  
Frédéric David ◽  
Laurent Baricault ◽  
Catherine Sapin ◽  
Xavier Gallet ◽  
Didier Marguet ◽  
...  
Keyword(s):  
Cell Surface ◽  
Surface Expression ◽  
Dipeptidyl Peptidase ◽  
Dipeptidyl Peptidase Iv ◽  
Cell Surface Expression ◽  
Terminal Domain ◽  
Dpp Iv

scholarly journals Rapid sequestration of DPP IV/CD26 and other cell surface proteins in an autophagic-like compartment in Caco-2 cells treated with forskolin

1995 ◽  
Vol 108 (5) ◽  
pp. 2109-2121
Author(s):  
L. Baricault ◽  
J.A. Fransen ◽  
M. Garcia ◽  
C. Sapin ◽  
P. Codogno ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Surface ◽  
Surface Expression ◽  
Dipeptidyl Peptidase ◽  
Dipeptidyl Peptidase Iv ◽  
Surface Proteins ◽  
Laser Scanning Microscopy ◽  
Cell Surface Expression ◽  
Confocal Laser ◽  
Cell Surface Proteins

The enterocytic differentiation of Caco-2 cells, a human colon adenocarcinoma cell line, is accompanied by the transcriptionally regulated expression of a subset of proteins and their correct sorting towards the cell surface. In the present work we have explored the possibility that post-translational events may interfere with this process by investigating the short term effects of a potent adenylyl cyclase activator, forskolin, on cell surface expression of dipeptidyl peptidase IV. Previous works have shown that this protein is targeted towards the apical domain through either a direct or an indirect route. Domain specific biochemical experiments demonstrate that cell surface expression of neosynthesized dipeptidyl peptidase IV rapidly decreases after a 1 hour forskolin treatment. Both initial basolateral and apical dipeptidyl peptidase IV membrane delivery were altered by forskolin treatment. Decrease of dipeptidyl peptidase IV cell surface expression was not restricted to this protein, since membrane expression of ‘525’ antigen, a basolateral protein and of sucrase-isomaltase, an apically targeted hydrolase, which unlike dipeptidyl peptidase IV mainly follows a direct route to the brush border membrane, also decreases. In addition endocytosis of proteins from the apical and from the basolateral domain was essentially unchanged, suggesting that forskolin's target may be located on the exocytic pathway. Confocal laser scanning microscopy and immuno-electron microscopy studies demonstrate that, within 5 minutes of forskolin treatment, the cell surface proteins studied accumulate in intracellular vesicles which were co-labeled with a polyclonal antibody raised against Lamp-1, a lysosomal membrane marker. Electron microscopy studies show that these vesicles display an autophagic-like morphology. Finally, biochemical experiments indicate that dibutyryl cAMP does not mimick the forskolin effect, thus suggesting that it is a cAMP-independent phenomenon.

scholarly journals Characterization, cell-surface expression and ligand-binding properties of different truncated N-terminal extracellular domains of the ionotropic glutamate receptor subunit GluR1

1996 ◽  
Vol 315 (1) ◽  
pp. 217-225 ◽  
Author(s):  
R. A. Jeffrey McILHINNEY ◽  
Elek MOLNÁR
Keyword(s):  
Cell Surface ◽  
Ligand Binding ◽  
Glutamate Receptor ◽  
Cell Membranes ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Receptor Subunit ◽  
Binding Studies ◽  
Terminal Domain ◽  
Glutamate Receptor Subunit

To identify the location of the first transmembrane segment of the GluR1 glutamate receptor subunit artificial stop codons have been introduced into the N-terminal domain at amino acid positions 442, 510 and 563, namely just before and spanning the proposed first two transmembrane regions. The resultant truncated N-terminal fragments of GluR1, termed NT1, NT2 and NT3 respectively were expressed in Cos-7 cells and their cellular distribution and cell-surface expression analysed using an N-terminal antibody to GluR1. All the fragments were fully glycosylated and were found to be associated with cell membranes but none was secreted. Differential extraction of the cell membranes indicated that both NT1 and NT2 behave as peripheral membrane proteins. In contrast NT3, like the full subunit, has integral membrane protein properties. Furthermore only NT3 is expressed at the cell surface as determined by immunofluorescence and cell-surface biotinylation. Protease protection assays indicated that only NT3 had a cytoplasmic tail. Binding studies using the selective ligand [3H]α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate ([3H]AMPA) demonstrated that NT3 does not bind ligand. Together these results indicate that the first transmembrane domain of the GluR1 subunit lies between residues 509 and 562, that the N-terminal domain alone cannot form a functional ligand-binding site and that this domain can be targeted to the cell surface provided that it has a transmembrane-spanning region.

scholarly journals Evidence for a role of dipeptidyl peptidase IV in fibronectin-mediated interactions of hepatocytes with extracellular matrix

1989 ◽  
Vol 262 (1) ◽  
pp. 327-334 ◽  
Author(s):  
G A Piazza ◽  
H M Callanan ◽  
J Mowery ◽  
D C Hixson
Keyword(s):  
Extracellular Matrix ◽  
Cell Surface ◽  
Rat Liver ◽  
Tissue Transglutaminase ◽  
Dipeptidyl Peptidase ◽  
Dipeptidyl Peptidase Iv ◽  
Type I ◽  
Cell Surface Glycoprotein ◽  
Dpp Iv ◽  
Fibronectin Binding

Dipeptidyl peptidase IV (DPP IV) is a cell surface glycoprotein which has been implicated in hepatocyte-extracellular matrix interactions [Hixson, DeLourdes, Ponce, Allison & Walborg (1984) Exp. Cell Res. 152, 402-414; Walborg, Tsuchida, Weeden, Thomas, Barrick, McEntire, Allison & Hixson (1985) Exp. Cell Res. 158, 509-518; Hanski, Huhle & Reutter (1985) Biol. Chem. Hoppe-Seyler 366, 1169-1176]. However, its proteolytic substrate(s) and/or binding protein(s) which mediate this influence have not been conclusively identified. Nitrocellulose binding assays using 125I-labelled DPP IV that was purified to homogeneity from rat hepatocytes revealed a direct interaction of DPP IV with fibronectin. Although fibronectin could mediate an indirect binding of DPP IV to collagen, no evidence was found for a direct binding of DPP IV to native or denatured Type I collagen. Fibronectin appeared to bind DPP IV at a site distinct from its exopeptidase substrate recognition site since protease inhibitors such as competitive peptide substrates and phenylmethanesulphonyl fluoride enhanced binding, possibly as a result of an altered conformation of DPP IV. To determine if fibronectin binding to DPP IV is involved in the interaction of fibronectin with the hepatocyte surface, the effect of various DPP IV inhibitors on 125I-fibronectin binding to isolated hepatocytes in suspension was examined. Kinetic studies revealed that inhibitors of DPP IV which enhanced fibronectin binding in vitro accelerated the initial binding of fibronectin to the cell surface where it was subsequently cross-linked (presumably by tissue transglutaminase) to as yet undefined components. Immunolocalization of fibronectin and DPP IV in normal rat liver sections showed that both proteins were present along the hepatocyte sinusoidal membrane. These observations, coupled with previous results showing that DPP IV is tightly bound to biomatrix isolated from rat liver (Hixson et al., 1984; Walborg et al., 1985), suggest that DPP IV binding to fibronectin may play a role in interactions of hepatocytes with extracellular matrix in vivo and possibly in matrix assembly.

Detection of dipeptidyl peptidase IV in glioma C6 and neuroblastoma SK-N-SH cell lines

1995 ◽  
Vol 73 (1-2) ◽  
pp. 113-115 ◽  
Author(s):  
Aleksi Sedo ◽  
Roberto P. Revoltella
Keyword(s):  
Cell Surface ◽  
Cell Line ◽  
Cell Lines ◽  
Neuroblastoma Cell ◽  
Dipeptidyl Peptidase ◽  
Dipeptidyl Peptidase Iv ◽  
Human Neuroblastoma Cell ◽  
Fluorescent Substrate ◽  
Human Neuroblastoma ◽  
Dpp Iv

The dipeptidyl peptidase IV (DPP-IV) activity of the rat glioma cell line C6 and the human neuroblastoma cell line SK-N-SH was investigated. DPP-IV fluorescent substrate was cleaved by both cell lines. The pH reaction optimum determined was typical for DPP-IV described in other cell models. The reaction was inhibited by specific inhibitors diprotins A and B. Enzyme activity was localized, both on the cell surface and intracellularly. Most of the DPP-IV activity was membrane bound. However, soluble intra-cellular activity was found in both cell lines. Secreted activity was not detected in either cell line. In the C6 line, but not in the SK-N-SH line, we demonstrated depression of the ratio of cell surface to total cell DPP-IV activity at higher cell densities, indicating possible enzyme redistribution during cell growth in culture. Identification of DPP-IV activity is the first step in our study of the role of DPP-IV in the neural system.Key words: dipeptidyl peptidase IV, glioma, neuroblastoma.

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