scholarly journals Chondroitin sulfate at the plasma membranes of cultured fibroblasts.

1983 ◽  
Vol 97 (4) ◽  
pp. 1288-1293 ◽  
Author(s):  
K Hedman ◽  
J Christner ◽  
I Julkunen ◽  
A Vaheri

We have previously shown that in confluent human fibroblast cultures chondroitin sulfate proteoglycan is a component of the fibronectin-containing pericellular matrix fibers. In the present work the distribution of chondroitin sulfate was studied in subconfluent cell cultures using antibodies that bind to a chemically defined carbohydrate fragment of chondroitinase ABC-modified chondroitin sulfate proteoglycan. Using immunofluorescence microscopy, we observed, in addition to the fibrillar matrix staining, chondroitin sulfate diffusely distributed at the cell surface. In indirect immunoferritin electron microscopy this staining corresponded to patchy binding of ferritin close (24 nm) to the outer aspect of the plasma membrane. The patchy organization appeared uniform in all cell surfaces. The cell surface chondroitin sulfate could not be removed from the plasma membrane by agents that dissociate electrostatic interactions. These data show that in fibroblasts chondroitin sulfate is a component of the outer aspect of the plasma membrane, and raise the possibility of an integral plasma membrane chondroitin sulfate proteoglycan.

1993 ◽  
Vol 106 (1) ◽  
pp. 55-65 ◽  
Author(s):  
M. Yamagata ◽  
S. Saga ◽  
M. Kato ◽  
M. Bernfield ◽  
K. Kimata

We showed previously that a large chondroitin sulfate proteoglycan, PG-M (also known as versican), inhibits cell-substratum adhesion, while basement membrane heparan sulfate proteoglycan (recently named perlecan) does not (Yamagata et al. (1989) J. Biol. Chem. 264, 8012–8018). To extend our understanding of the adhesive function of these proteoglycans, we examined the pericellular localization of the proteoglycans and their ligands and also that of some matrix receptors and cytoskeletal molecules in various fibroblast culture systems. PG-M was abundant in the subcellular space of fibroblasts, but was excluded selectively from focal contacts where vinculin, integrins and fibronectin were localized. Hyaluronan, CD44 and tenascin were distributed similarly as PG-M. In contrast, perlecan was associated with fibronectin and was included in focal contacts. Syndecan-1, a membrane heparan sulfate/chondroitin sulfate proteoglycan, was associated with fibronectin at the cell surface, partly at focal contacts and in association with stress fibers. Thus, complexes of PG-M with hyaluronan, tenascin and CD44, are not involved in focal contacts. On the other hand, perlecan and syndecan-1 together with fibronectin may participate in focal contacts. The difference in localization between these proteoglycans may be related to their glycosaminoglycan content and to their distinctive roles in cell-substratum adhesion.


1995 ◽  
Vol 270 (45) ◽  
pp. 27206-27212 ◽  
Author(s):  
Constanze I. Seidenbecher ◽  
Karin Richter ◽  
Uwe Rauch ◽  
Reinhard Fässler ◽  
Craig C. Garner ◽  
...  

1990 ◽  
Vol 111 (6) ◽  
pp. 3177-3188 ◽  
Author(s):  
W B Stallcup ◽  
K Dahlin ◽  
P Healy

The NG2 chondroitin sulfate proteoglycan is a membrane-associated molecule of approximately 500 kD with a core glycoprotein of 300 kD. Both the complete proteoglycan and a smaller quantity of the 300-kD core are immunoprecipitable with polyclonal and monoclonal antibodies against purified NG2. From some cell lines, the antibodies coprecipitate NG2 and type VI collagen, the latter appearing on SDS-PAGE as components of 140 and 250 kD under reducing conditions. The immunoprecipitation of type VI collagen does not seem to be due to recognition of the collagen by the antibodies, but rather to binding of the collagen to NG2. Studies on the NG2-type VI collagen complex suggest that binding between the two molecules is mediated by protein-protein interactions rather than by ionic interactions involving the glycosaminoglycans. Immunofluorescence double labeling in frozen sections of embryonic rat shows that NG2 and type VI collagen are colocalized in structures such as the intervertebral discs and arteries of the spinal column. In vitro the two molecules are highly colocalized on the surface of several cell lines. Treatment of these cells resulting in a change in the distribution of NG2 on the cell surface also causes a parallel change in type VI collagen distribution. Our results suggest that cell surface NG2 may mediate cellular interactions with the extracellular matrix by binding to type VI collagen.


1982 ◽  
Vol 94 (1) ◽  
pp. 28-35 ◽  
Author(s):  
E G Hayman ◽  
A Oldberg ◽  
G R Martin ◽  
E Ruoslahti

We used antibodies raised against both a heparan sulfate proteoglycan purified from a mouse sarcoma and a chondroitin sulfate proteoglycan purified from a rat yolk sac carcinoma to study the appearance and distribution of proteoglycans in cultured cells. Normal rat kidney cells displayed a fibrillar network of immunoreactive material at the cell surface when stained with antibodies to heparan sulfate proteoglycan, while virally transformed rat kidney cells lacked such a surface network. Antibodies to chondroitin sulfate proteoglycan revealed a punctate pattern on the surface of both cell types. The distribution of these two proteoglycans was compared to that of fibronectin by double-labeling immunofluorescent staining. The heparan sulfate proteoglycan was found to codistribute with fibronectin, and fibronectin and laminin gave coincidental stainings. The distribution of chondroitin sulfate proteoglycan was not coincidental with that of fibronectin. Distinct fibers containing fibronectin but lacking chondroitin sulfate proteoglycan were observed. When the transformed cells were cultured in the presence of sodium butyrate, their morphology changed, and fibronectin, laminin, and heparan sulfate proteoglycan appeared at the cell surface in a pattern resembling that of normal cells. These results suggest that fibronectin, laminin, and heparan sulfate proteoglycan may be complexed at the cell surface. The proteoglycan may play a central role in assembly of such complexes since heparan sulfate has been shown to interact with both fibronectin and laminin.


2018 ◽  
Author(s):  
Masahiko Takemura ◽  
Fredrik Noborn ◽  
Jonas Nilsson ◽  
Eriko Nakato ◽  
Tsu-Yi Su ◽  
...  

AbstractProteoglycans, a class of carbohydrate-modified proteins, often modulate growth factor signaling on the cell surface. However, the molecular mechanism by which proteoglycans regulate signal transduction is largely unknown. In this study, using a recently-developed glycoproteomic method, we found that Windpipe (Wdp) is a novel chondroitin sulfate proteoglycan (CSPG) in Drosophila. Wdp is a single-pass transmembrane protein with leucin-rich repeat (LRR) motifs and bears three CS sugar chain attachment sites in the extracellular domain. Here we show that Wdp modulates the Hedgehog (Hh) pathway. Overexpression of wdp inhibits Hh signaling in the wing disc, which is dependent on its CS chains and the LRR motifs. Conversely, loss of wdp leads to the upregulation of Hh signaling. Furthermore, knockdown of wdp increase the cell surface accumulation of Smoothened (Smo), suggesting that Wdp inhibits Hh signaling by regulating Smo stability. Our study demonstrates a novel role of CSPG in regulating Hh signaling.


1993 ◽  
Vol 154 (1-2) ◽  
pp. 121-124 ◽  
Author(s):  
Junichi Shioi ◽  
Lawrence M. Refolo ◽  
Spiros Efthimiopoulos ◽  
Nikolaos K. Robakis

1993 ◽  
Vol 120 (1) ◽  
pp. 25-35 ◽  
Author(s):  
G M Lee ◽  
F Zhang ◽  
A Ishihara ◽  
C L McNeil ◽  
K A Jacobson

Nanovid (video-enhanced) microscopy was used to determine whether lateral diffusion in the plasma membrane of colloidal gold-tagged lipid molecules is confined or is unrestricted. Confinement could be produced by domains within the plane of the plasma membrane or by filamentous barriers within the pericellular matrix. Fluorescein-phosphatidylethanolamine (F1-PE), incorporated into the plasma membranes of cultured fibroblasts, epithelial cells and keratocytes, was labeled with 30-nm colloidal gold conjugated to anti-fluorescein (anti-F1). The trajectories of the gold-labeled lipids were used to compute diffusion coefficients (DG) and to test for restricted motion. On the cell lamella, the gold-labeled lipids diffused freely in the plasma membrane. Since the gold must move through the pericellular matrix as the attached lipid diffuses in the plasma membrane, this result suggests that any extensive filamentous barriers in the pericellular matrix are at least 40 nm from the plasma membrane surface. The average diffusion coefficients ranged from 1.1 to 1.7 x 10(-9) cm2/s. These values were lower than the average diffusion coefficients (DF) (5.4 to 9.5 x 10(-9) cm2/s) obtained by FRAP. The lower DG is partially due to the pericellular matrix as demonstrated by the result that heparinase treatment of keratocytes significantly increased DG to 2.8 x 10(-9) cm2/s, but did not affect DF. Pericellular matrix viscosity was estimated from the frictional coefficients computed from DG and DF and ranged from 0.5 to 0.9 poise for untreated cells. Heparinase treatment of keratocytes decreased the apparent viscosity to approximately 0.1 poise. To evaluate the presence of domains or barriers, the trajectories and corresponding mean square displacement (MSD) plots of gold-labeled lipids were compared to the trajectories and MSD plots resulting from computer simulations of random walks within corrals. Based on these comparisons, we conclude that, if there are domains limiting the diffusion of F1-PE, most are larger than 5 microns in diameter.


Blood ◽  
1996 ◽  
Vol 87 (3) ◽  
pp. 1123-1133 ◽  
Author(s):  
FO Smith ◽  
C Rauch ◽  
DE Williams ◽  
CJ March ◽  
D Arthur ◽  
...  

In our efforts to produce monoclonal antibodies that recognize cell- surface antigens expressed by hematopoietic precursor and stromal cells, we generated a monoclonal antibody, 7.1, which recognizes a 220- to 240-kD cell-surface protein whose N-terminal amino acid sequence is identical to the rat NG2 chondroitin sulfate proteoglycan molecule. This chondroitin sulfate proteoglycan, previously reported to be expressed by human melanoma cells, was not found to be expressed by normal hematopoietic cells, nor was it expressed on the cell surface of cell lines of hematopoietic origin including cell lines with 11q23 abnormalities. It was found on the cell surface of acute myeloid leukemia (AML) blasts and cell lines derived from nonhematopoietic tissues. Samples of leukemic marrow from 166 children with AML enrolled on Childrens Cancer Group protocol 213 were evaluated for cell-surface expression of this proteoglycan molecule. In 18 of 166 (11%) patient samples, greater than 25% of leukemic blasts expressed the NG2 molecule. These 18 patients had a poorer outcome with respect to survival (P = .002) and event-free survival (P = .035) with an actuarial survival at 4 years of 16.7%. Blast cell expression of the NG2 molecule was strongly associated with French-American-British M5 morphology (P < .0001) and abnormalities in chromosome band 11q23, site of the MLL gene. These results show that the NG2 molecule is expressed by malignant hematopoietic cells that have abnormalities in chromosome band 11q23, suggesting that antibody 7.1 may be useful in the rapid identification of this group of poor-prognosis patients.


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