摘要:

AbstractThe glycoprotein laminin appears to function in the attachment of various epithelial cells to basement membranes. We examined whether its putative cell‐adhesive activity could be analyzed in a simple, one‐component model system—the agglutination of erythrocytes. Laminin is a potent agglutinin of aldehyde‐fixed sheep and human erythrocytes, with half‐maximal agglutination of 0.8 μg/ml in a standard hemagglutination assay. Inhibitors of this hemagglutinating activity include gangliosides and certain charged phospholipids. The spectrum of molecules is similar but not identical to inhibitors of the hemagglutinating activity of the adhesive glycoprotein fibronectin. Laminin is much less biologically active in three other assays for fibronectin biological activity involving cell spreading on tissue culture substrates, attachment of fibroblastic cells to type I collagen, and restoration of normal morphology to transformed fibroblasts. The adhesive glycoproteins laminin and fibronectin therefore differ markedly in biological activities in several specific adhesion assays; however, they resemble one another in binding to heparin, collagen, and cell surfaces and in their agglutini

ISSN:0021-9541    

DOI:10.1002/jcp.1041140302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe renal cell line LLC‐PK1contransports Na andD‐glucose from the apical to the basolateral side of the cell monolayer, and the short‐circuit current (Isc) measures the net amount of Na transported. Under conditions of maximal cotransport, the addition of phlorizin or removal of Na rreversibly decreased oxygen consumption by one‐hal. In the absence of glycolytic substrates, α‐methyl‐D‐glucoside stimulated Isc and oxygen consumption, although the Isc came to a steady state 50% less than when glycolytic substrates were present. The addition of other aerobic substrates did not increase Isc; however, when non‐contransported glycolytic substrates were introduced the Isc returned to a maximum with an associated fall in oxygen consumption and increased lactate production. Thus, in the absence of glycolytic substrates aerobic ATP formation may be rate‐limiting for Na,D‐glucose contansport. For this epithelium glycolysis makes an impotant contribution to the provision of energy or transport. Oxygen consumption does not correlate well with Isc and is not a good measured off the ener

ISSN:0021-9541    

DOI:10.1002/jcp.1041140303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractLiposomes made by sonication of egg yolk phosphatidyl choline support the proliferation of low‐density bovine vascular and corneal endothelial cells, and vascular smooth muscle cells maintained on basement laminacoated dishes and exposed to a defined medium supplemented with transferrin. The optimal growth‐promoting effect of phosphatidyl choline was observed at concentrations of 25 μg/ml for low‐density cultures of vascular smooth muscle cells, and 100 μg/ml for vascular and corneal endothelial cells. The growth rate and final cell density of vascular endothelial cells exposed to a synthetic medium supplemented with transferrin and either high‐density lipoproteins or phosphatidyl choline has been compared. Although cultures exposed to phosphatidyl choline reached a final cell density similar to that of cultures exposed to high‐density lipoproteins, they had a longer average doubling time (17 h vs. 12 h) during their logarithmic growth phase and a shorter lifespan (17 generations vs. 30 generations). Similar observations were made in the case of vascular smooth muscle cells or bovine corneal endothelial cells maintained in medium supplemented with transferrin, fibroblast growth factor (FGF) or epidermal growth factor (EGF), and insulin and exposed to either high‐density lipoproteins or phosphatidyl choline. Since phosphatidyl choline can, for the most part, replace highdensity lipoproteins in supporting the proliferation of various cell types, it is likely that the growth stimulating signal conveyed by high‐density lipoproteins is associated with its polar lipid fraction, which is composed mostly of phosph

ISSN:0021-9541    

DOI:10.1002/jcp.1041140304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractTreatment of a variety of cultured human tumor cells with low levels (40–80 μM) of adenosine 5′‐dephosphate (ADP) or adenosine 5′ ‐triphosphate (ATP) has produced arrest of these cells in the S phase of their cycle followed by cellular death. ADP and ATP are demonstrated to be incorporated into the cellular acid‐soluble nucleotide pools, presumably by permeation through the plasma membrane of these cells. Since AMP, adenosine, 3′,5′ cycle AMP, or a variety of diadenosine polyhosphates do not produce similar cytostatic effects or similar alterations of the cellular acid‐soluble nucleotide pools, we suggest that the effects of ADP and ATP are not due to their prior breakdown or modification. Cultured animal cells have been widely acknowledged not to incroporte acid‐soluble adenine nucleotides although incorporation of exogenous intact nucleoside monophosphate into cellular pools has been demonstrated in a few cases. A 48‐hour treatment of logarithmically growing human tumor cells with 40mUM of ADP or ATP produced substantial arrest of cell populations in the S phase of their cycle and a dramatic reduction in total cellular uridine 5′ ‐triphosphate (UTP) pools. AMP, adenosine, 3′,5′ cyclic AMP, Ap3A, Ap4A or Ap5A produced small and dissimilar effects. The experiments reported here suggest that the plasma membranes of several lines of human tumor cells are premeable to low levels of intact ADP and ATP. The suggestion of en bloc incorporation of low ADP and ATP levels into human tumor cells is supported by the almost identical effects of ADP and ATP on total cellular acid‐soluble nucleotide pools and cellular growth. The rapid conversion of intracellular ADP pools into ATP

ISSN:0021-9541    

DOI:10.1002/jcp.1041140305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractAngiotensin peptides (AI, AII, AIII) increased the rate of Na+accumulation by smooth muscle cells (SMC) cultured from rat aorta. The stimulatory effect of All on Na+uptake was observed which Na+exodus via the Na+/K+pump was blocked either by ouabain or by the removal of extracellular K+. All was at least ten times more potent than AIII and about 100 times more potent than AI in stimulating Na+uptake. Saralasin had little effect on Na+uptake by itself but almost completely blocked the increase caused by All. The stimulation of net Na+entry by AI, but not AII, was prevented by protease inhibitors. The stimulation of Na+uptake was almost completely blocked by amiloride. Tetrodotoxin, which prevented veratridine from increasing Na+uptake, had no effect on the response to AII. Angiotensin increased the rate of ouabain‐sensitive86Rb+uptake (Na+/K+pump activity) but had no effect on ouabain‐sensitive ATPase activity in frozen‐thawed SMC or in microsomal membranes isolated from cultured SMC. The stimulation of ouabain‐sensitive86Rb+uptake by All was blocked by saralasin. Omitting Na+from the external medium prevented All from increasing86Rb+uptake. All had no effect on cell volume or cyclic AMP levels in the cultured SMC. These results suggest that angiotensin peptides activate an amiloride‐sensitive Na+transporter which supplies the Na+/K+pump with more Na+, its rate‐limitin

ISSN:0021-9541    

DOI:10.1002/jcp.1041140306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThree cell lines from resident macrophages of BALB/c mice and four from activated macrophages of the same strain were isolated by infection with simian virus 40 (SV40). A majority of these cells showed dependency on L cell‐conditioned medium (LCM), which is necessary for proliferation of normal macrophages in vitro. Somatic cell hybridization was applied in the study of macrophage growth responsiveness. A macrophage cell line (BR 15) with strict dependency on LCM for growth was fused to a Chinese hamster cell line (hs222‐16); it was found that dependency on LCM was a dominant trait in the hybrids. Following fusion fo a macrophage cell line (BAM3) which grew without LCM to hs222‐16, a large number of colonies appeared in the selection medium containing LCM . Four hybrids not requiring LCM for growth were selected in an LCM‐free culture, and their hybrid properties were examined. Three out of the four hybrids secreted colony‐stimulating factor (CSF) constitutively, whereas the fourth secreted no CSF. The level of acid phosphatase activity in the hybrids was higher than in the parent cells. Two peaks of CSF activity were observed after gel filtration chromatography of conditioned medium: One was eluted at molecular weight of 36,000 and the other

ISSN:0021-9541    

DOI:10.1002/jcp.1041140307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractNeovascularization was studied in the chorioallantoic memebrane of the chick embryo after implantation of bovine aortic endothelial and smooth muscule cells, Swiss and BALB/c 3T3 cells and human diploid fibroblasts cultured separately on microcarrier beads. Quantitative analysis of neovascularization indicated a 3 1/2‐fold increase in the number of blood vessels responding to endothelial cells while smooth muscle cells induced a twofold increase when compared to the response of beads without cells. Skin fibroblasts and Swiss 3T3 cells did not elicit a comparable response. The marked angiogenic response induced by endothelial cells was characterized by a 137% increase in total vessel length and a 35% increase in average vessel area when compared to controls. Two of the properties required for an angiogenesis factor—stimulation of cellular migration and proliferation—can also be demonstrated using endothelial cell‐conditioned medium in cell culture systems. Medium from cultured bovine aortic endothelium stimulates DNA synthesis, proliferation, and migration of smooth muscle cells. In adition, conditioned media from both endothelial cells and smooth muscle cells produced an angiogenic response in the chorioallantoic membrane assay, which was comparable to that produced by intact cells growing on microcarrier beads. Similar responses were not evident with medium conditioned by other cell types. These results indicate the potential importance of endothelial cells and endothelial cell products in regulating blood vessel

ISSN:0021-9541    

DOI:10.1002/jcp.1041140308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractUsing a serum‐free medium supplemented with hormones and growth factors, which included epidermal growth factor (EGF), we investigated the binding and processing‐degradation of [125I]EGF in WI‐38 cells of various in vitro ages. The binding and processing‐degradation systems of these cells remained esentially unchanged throughout their lifespan. The number of specific [125I]EGF binding sites per cell increased as the cultures senesced, thought the number of specific binding sites per μm2(surface area) remained constant. The kinetics of ligand degradation as well as the qualitative and quantitative nature of the degradation products also remained essentially unchanged throughout the life‐span. The only consistent alteration in any of the binding parameters measured was the slight decrease in the apparent kdof the ligand‐receptor complex, independent of temperature. Quantitation of EGF‐stimulated DNA synthesis revealed a decrease in the percentage of cells incorporating [3H]thymidine ([3H]TdR) during a 30‐h exposure from 45% in young cells to 0.25% in senescent cells, although [125I]EGF binding or processing‐degradation did not differ significantly in yong and old cells. Thus, EGF binding does not decr

ISSN:0021-9541    

DOI:10.1002/jcp.1041140309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe potent tumor promoter 12‐0‐tetradecanoyl phorbol‐13‐acetate (TPA) is alos an excellent mitogen for 3T3 cells. We have previously isolated two independent variants, 3T3‐TNR‐2 and 3T3‐TNR‐9, that are unable to divide in response to TPA (Butler‐Gralla and Herschman, 1981). We have now tested tow components of the pleiotypic response, elevation of 2‐deoxyglucose uptake and ornithine decarboxylase induction, in these cells. Basal levels of 2‐deoxyglucose uptake were nearly tenfold higher in confluent 3T3‐TNR‐2 and 3T3‐TNR‐9 cells than in 3T3 cells. In contrast, basal ornithine decarboxylase levels were five‐ to tenfold lower in the variants. TPA stimulation of 2‐deoxyglucose uptake was as great in absolute terms in the variant cell lines as that of 3T3 cells but was only half that observed with serum. TPA was unable to induce any elevation of ornithine decarboxylase in 3T3‐TNR‐9 cells. treated with TPA, the maximal specific activity in the variant was less than

ISSN:0021-9541    

DOI:10.1002/jcp.1041140310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe rat PC12 pheochromocytoma cell line exhibits biological responses to both nerve growth factor (NGF) and epidermal growth factor (EGF). The existence of receptors and biological responses on a common cell for these two well‐characterized polypeptide growth factors makes this an attractive system for comparison of ligand binding and processing. Both NGF and EGF are bound to PC12 cells in a competable form at 4°C. At 37°C both ligands are “sequestered”, but at different rates and to different extents. While sequestration happens rapidly and nearly quantitatively for bound EGF, the dissociation reation appears to compete favorably with NGF sequestration. Both EGF and NGF are degraded by PC12 cells. Sequestered EGF, however, is degraded to a greater extent than sequeste

ISSN:0021-9541    

DOI:10.1002/jcp.1041140311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY