摘要:

AbstractHuman endothelial cells release components into the growth medium that stimulate cell‐substratum adhesion. Several macromolecular components were isolated by ultracentrifugation of the endothelial cell conditioned medium. The components were heterogeneous, consisting of several sizes when examined by sedimentation velocity and gel filtration. When the extracellular components were evaluated by electron microscopy, structurally discrete particles were observed. The extracellular components and the complexes mediated cell‐substratum adhesion to both human umbilical and arterial endothelial cells. The majority of the extracellular components that promote endothelial cell adhesion were pelleted by ultracentrifugation. Although the complexes contained fibronectin, antibodies to fibronectin did not inhibit cell adhesion to the complexes. Significant inhibition of endothelial cell adhesion was observed in the presence of heparin and heparan sulfate. The supernatant fraction following ultracentrifugation of the growth medium contained a component that suppressed endothelial cell adhesion to culture dishes coated with fibronectin, type I collagen, and endothelial cell complexes. SDS‐polyacrylamide gel electrophoresis indicated that the complexes contained several components, and the majority of the large‐molecular‐weight components were pelleted by ultracentrifugation. The conditioned medium from human endothelial cells contains specific complexes that promote cell‐substratum adhesion and components that suppress cell‐substr

ISSN:0021-9541    

DOI:10.1002/jcp.1041280302

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

年代:1986

数据来源: WILEY

摘要:

AbstractWe have studied the effect of methylglyoxal‐bis (guanylhydrazone) (MGBG) and novobiocin on the accumulation of specific mRNAs in serum‐stimulated ts13 cells (a temperature‐sensitive mutant of the BHK cell line). The RNAs studied included: c‐myc, v‐ras, ornithine decarboxylase, β‐actin, histone H3, and those represented by clones p2F1 and p1B6 (Hirschhorn et al., Proc. Natl, Acad. Sci. USA,81: 6004, 1984) All these RNAs accumulated at higher levels when quiescent cells were serum stimulated for 16 h. Both MGBG (25 μM and 100 μM) and novobiocin (200 μg/ml) effectively prevented the transition from G0to S phase. We found that 100 μM MGBG induced an overaccumulation of c‐myc RNA while H3 RNA was decreased, and the steady‐state levels of all other RNAs were the same as in cells stimulated without the drug. Novobiocin prevented the serum‐induced increase in the amount of all RNAs, which remained at the same levels as in quiescent cells, with the exception of c‐myc, which again accumulated at a higher level in drug‐treated cells than in serum‐stimulated untreated cells. The possible significance o

ISSN:0021-9541    

DOI:10.1002/jcp.1041280303

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

年代:1986

数据来源: WILEY

摘要:

AbstractWe have investigated the protein phosphorylation systems present in cultured bovine aortic and pulmonary artery endothelial cells. The cells contain cyclic AMP‐dependent protein kinase, three calcium/calmodulin‐dependent protein kinases, protein kinase C, and at least one tyrosine kinase. No cyclic GMP‐dependent protein kinase activity was found. The cells also contained numerous substrates for cyclic AMP‐dependent protein kinase and protein kinase C. Fewer substrates were found for the calcium/calmodulin‐dependent protein kinases. There was little difference between either protein kinase activities or substrates when pulmonary artery endothelium was compared to aortic endothelium grown under similar culture conditions. It is likely that these various protein kinases and their respective substrate proteins are involved in mediating several of the actions of the hormones and drugs which affect the vascular en

ISSN:0021-9541    

DOI:10.1002/jcp.1041280304

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

年代:1986

数据来源: WILEY

摘要:

AbstractIn the presence of methotrexate, cultured human choriocarcinoma (BeWo) cells undergo a differentiative response that resembles normal trophoblastic development. In the current study, the effects of cell number and population density on drug‐induced conversion of BeWo cells from the cytotrophoblast‐like to the syncytiotrophoblastlike phenotype were investigated using as markers of differentiation formation of “giant” cells, a process shown to require exogenous purines, and expression of placental (heat‐stable) alkaline phosphatase. Giant cell formation, assessed by determination of cell volumes, was reduced in crowded cultures, and addition of hypoxanthine to growth media partially restored methotrexate‐induced cell enlargement. Cellular uptake of methotrexate, assessed by following the loss of methotrexate from cell culture fluids during drug exposures, was two‐threefold greater in sparsely populated than in densely populated cultures. Although the concentration of methotrexate in culture fluids of crowded cultures declined during exposures of 48 hr, the amount of extracellular drug remaining at 48 hr was well above the threshold for induction of the differentiative response. When culture population was held constant and population density was manipulated by varying the substratum available to cells, methotrexate‐induced cell enlargement was inversely related to population density. Expression of placental alkaline phosphatase, salvage of exogenous hypoxanthine, and synthesis of RNA were also reduced at high population densities. These results indicate that expression of markers of methotrexate‐induced differentiation of BeWo cells was inhibited in a density‐dependent manner that may have been related to reduced cellular uptake of the inducing agent and of exogenous nutrients (purines)

ISSN:0021-9541    

DOI:10.1002/jcp.1041280305

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

年代:1986

数据来源: WILEY

摘要:

AbstractTemperature‐sensitive mutants have revealed a region of the herpes simplex virus 1 genome that affects both the uptake of hexose and the synthesis of heat shock proteins. Other inducers of heat‐shock proteins, namely heat shock itself and arsenite, likewise induce an increased uptake of hexose. The increased uptake, like that induced by insulin, is insensitive to the presence of actinomycin D or cycloheximide. It is concluded that an increased hexose uptake, reflecting an activation or relocation of existing hexose transport protein, is general biochemical response of stressed ce

ISSN:0021-9541    

DOI:10.1002/jcp.1041280306

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

年代:1986

数据来源: WILEY

摘要:

AbstractA covalent conjugate of alpha‐foetoprotein (AFP) and horseradish peroxidase (HRP) has been used to follow, at the ultrastructural level, the pathway of AFP uptake and translocation in a rat rhabdomyosarcoma cell line. The cells were incubated for several times at 4°C and/or 37°C, and fixed. AFP‐HRP was found to enter the cells via coated pits and receptosomes and to move to tubular elements of the trans‐reticular portion of the Golgi. Some observations suggest that AFP can be recycled back to the cell surface. On the other hand, the cells were incubated with a noncovalent conjugate of AFP and3H‐arachidonic acid [3H‐(20:4)], and the uptake of the fatty acid molecules studied by ultrastructural autoradiography. The cytoplasmic labeling, very low after an incubation in the presence of [3H‐(20:4)]‐AFP for 2 hours at 4°C, increased rapidly after transfer of the cells for 5 minutes to 37°C. These observations support the hypothesis that AFP plays a role in the intracellular delivery of polyunsatu

ISSN:0021-9541    

DOI:10.1002/jcp.1041280307

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

年代:1986

数据来源: WILEY

摘要:

AbstractWell coupled mitochondria were isolated from transplantable chicken hepatoma induced by MC‐29 virus. The mitochondrial phosphate‐dependent and phosphate‐independent glutaminase activities were increased compared with those from normal chicken liver. Glutamate dehydrogenase was undetectable in the tumor mitochondria. Oxypolarographic tests showed the following: (1) glutamine oxidation was prominent in the tumor mitochondria and was mediated through an NAD‐linked reaction, while mitochondria from the liver showed a feeble glutamine oxidation; (2) glutamine oxidation by tumor mitochondria was inhibited either by aminooxyacetate, inhibitor of transaminases, or prior incubation of mitochondria with DON (6‐diazo‐5‐oxonorleucine), which inhibited mitochondrial glutaminases. Bromofuroate, inhibitor of glutamate dehydrogenase, had little or no effect; and (3) glutamate oxidation was also inhibited by aminooxyacetate, while it was not affected by DON. These findings clearly show a high glutamate oxidation activity in the hepatoma and indicate that the product of glutamine hydrolysis, glutamate, is catabolized via transamination in the mitochondria

ISSN:0021-9541    

DOI:10.1002/jcp.1041280308

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

年代:1986

数据来源: WILEY

摘要:

AbstractFibronectin isolated from the conditioned medium of monolayer cultures of baby hamster kindey (BHK) cells and several ricin‐resistant (Ric®) mutants derived from them express differences in N‐glycosylation. The asparaginelinked oligosaccharides of BHK cell‐derived fibronectin consist largely of complex chains, whereas hybrid and/or high‐mannose chains are present in the fibronectins of mutant cell lines. The fibronectins exhibiting different glycosylation patterns are incorporated to similar extents into the cell‐layer of human skin fibroblasts. In contrast, mutant cells retain significantly less endogenously produced fibronectin than BHK cells and also incorporate less human cellular fibronectin into a pericellular matrix. In vitro adhesion assays show that mutant cells attach to and spread relatively poorly on fibronectinor type IV collagen‐coated substrata but interact as well as do BHK cells with a laminin substratum. These results indicate that asparagine‐linked oligosaccharides of fibronectin are not required for the binding and incorporation of the molecule into cell layers, but, as constituents of other cellular glycoproteins, they do modulate the ability of BHK cells to interact with some mat

ISSN:0021-9541    

DOI:10.1002/jcp.1041280309

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe lipid‐free apolipoproteins of human high density lipoprotein (HDL) have been assayed for their ability to substitute for native HDL in promoting the growth of a SV40‐transformed REF52 cell line in serum‐free medium. Total HDL‐apolipoproteins (apoHDL) were found to mimic almost exactly the growth promoting effects of whole HDL. The apoHDL‐associated growth promoting activity eluted from a Sephacryl S‐200 column in two separate fractions coin‐ciding with the protein peaks of apolipoprotein A‐I and the C group of apolipoproteins. These two fractions, designated S‐II and S‐IV, respectively, acted additively in promoting WT1A cell growth when tested at saturating concentrations. The active component in the S‐II fraction maximally stimulated WT1A cell growth at 40–60 μg/ml and was identified as apolipoprotein A‐1 by NaDodSO4polyacrylamide gel electrophoresis and affinity chromatography on anti‐(apoA‐I). The active component in the S‐IV fraction was maximally active at 1–2 μg/ml and was identified as apolipoprotein C‐III by DEAE ion exchange high pressure liquid chromatography and polyacrylamide gel electrophoresis (at pH 8.3) in 6 M urea. These results indicate that the growth promoting effect of HDL on WT1A cells is mediated via the HDL‐apolipoproteins, A‐I and C‐III, and that the mechanism responsible does not necessarily involve their participation in the uptak

ISSN:0021-9541    

DOI:10.1002/jcp.1041280310

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

年代:1986

数据来源: WILEY

摘要:

AbstractRecombinant murine GM‐CSF produced inEscherichia coliwas purified to homogeneity and tested in parallel with purified native GM‐CSF. Both recombinant and native GM‐CSF stimulated granulocyte and/or macrophage colony formation by adult and fetalmouse progenitor cells, and with adult marrow cells the specific activity of the recombinant GM‐CSF (25 × 108U/mg) was similar to that of the native form (15 × 108U/mg). At high concentrations (>200 U/ml), both forms of GM‐CSF also stimulated eosinophil colony formation by adult marrow cells and, at very high concentrations (>800 U/ml), megakaryocyte and some erythroid and mixed‐erythroid colony formation. Recombinant GM‐CSF was as effective in stimulating the proliferation of the GM‐CSF‐dependent cell line FD as the native molecule. Both recombinant and native GM‐CSF were able to induce partial differentiation in colonies of WEHI‐3B myeloid leukemic cells. Recombinant GM‐CSF competed effectively for the binding of125l‐labeled native GM‐CSF to hemopoietic cells, and anti‐serum to recombinant GM‐CSF also neutralized the biological activity of native GM‐CSF. The bacterially synthesized GM‐CSF was a slightly more effective stimulus for megakayocyte colony formation than then native molecule. The demonstration that purified bacterially synthesized GM‐CSF is biologically active in vitro now permits studies to be undertaken

ISSN:0021-9541    

DOI:10.1002/jcp.1041280311

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

年代:1986

数据来源: WILEY