摘要:

AbstractThree types of murine tumors, B‐16 melanoma, A‐10 carcinoma, and S‐180 sarcoma, were shown to contain elevated glycosaminoglycan (GAG) concentrations in vivo as compared to normal muscle or subcutaneous tissue. Hyaluronate was especially concentrated in the A‐10 carcinoma, which contained approximately six times more hyaluronate than subcutaneous tissue and 18 times more than muscle. In all three tumors, chondroitin sulfates, especially chondroitin‐4‐sulfate, were present in higher concentrations than in the. normal tissues. In culture, however, all three tumor cell lines produced less than 5% as much GAG as mouse fibroblasts, when measured by incorporation of [3H] acetate or by chemical analysis. Varying the culture passage number or the medium composition, ie, glucose, serum, and insulin concentrations, had little effect on GAG synthesis by the tumor cells. The low GAG levels in the tumor cell cultures were not due to hyaluronidase activity in their media. In an attempt to mimic possible host‐tumor cell interactions that could account for the elevated GAG levels in vivo, tumor cells were cocultured with fibroblasts, but no stimulation above the amount made by the tumor cells alone plus that by the fibroblasts alone was observed. Conditioned media from the tumor cells, either dialyzed or not against fresh complete medium, had no effect on fibroblast GAG synthesis. Tumor extracts, however, were found to stimulate synthesis of hyaluronate by fibroblasts. Stimulation by extracts of A‐10 carcinoma was greater than and additive to that of serum. The above results strongly suggest that GAG production in these tumors is in pail regulated by host‐t

ISSN:0730-2312    

DOI:10.1002/jcb.240250402

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe basal ATPase activity of 30S dynein, whether obtained by extraction of ciliary axonemes with a high (0.5 M NaCl) or low (1 mM Tris‐0.1 mM EDTA) ionic strength buffer is increased by NaCl, NaNO3, and Na acetate, with NaNO3causing the largest increase. The calmodulin‐activated ATPase activity of 30S dynein is also increased by addition of NaCl, NaNO3, or Na acetate, but the effects are less pronounced than on basal activity, so that the calmodulin activation ratio (CAR) decreases to 1.0 as salt concentration increases to 0.2 M. These salts also reduce the CAR of 14S dynein ATPase to 1.0 but by strongly inhibiting the calmodulin‐activated ATPase activity and only slightly inhibiting the basal activity. Sodium fluoride differs both quantitatively and qualitatively from the other three salts studied. It inhibits the ATPase activity of both 14S and 30S dyneins at concentrations below 5 mM and, by a stronger inhibition of the calmodulin‐activated ATPase activities, reduces the CAR to 1.0. Na acetate does not inhibit axonemal ATPase, nor does it interfere with the drop in turbidity caused by ATP and extracts very little protein from the axonemes. NaCl and, especially, NaNO3, cause a slow decrease in A350of an axonemal suspension and an inhibition of the turbidity response to ATP. NaF, at concentrations comparable to those that inhibit the ATPase activities of the solubilized dyneins, also inhibits axonemal ATPase activity and the turbidity response. Pretreatment of demembranated axonemes with a buffer containing 0.25 M sodium acetate for 5 min followed by extraction for 5 min with a buffer containing 0.5 M NaCl and resolution of the extracted dynein on a sucrose density gradient generally yields a 30S dynein that is activated by calmodulin in a heterogeneous manner, ie, the “light” 30S dynein ATPase fractions are more activated than the “heavy” 30S dynein fractions. These results demonstrate specific anion effects on the basal and calmodulin‐activated dynein ATPase activities, on the extractability of proteins from the axoneme, and on the turbidity response of demembranated axonemes to ATP. They also provide a method that frequently yields 30S dynein fractions with ATPase activities that are activated over twofold by

ISSN:0730-2312    

DOI:10.1002/jcb.240250403

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

年代:1984

数据来源: WILEY

摘要:

AbstractA growth factor for rat and human mammary tumor cells (MTGF‐Pit) was isolated from lyophilized powders of whole sheep pituitaries by a rapid four‐step procedure utilizing acetic acid extraction, heating at 93°C, and sequential chromatography in 0.10 M acetic acid on sulphopropyl Sephadex and Sephadex G‐50. From 10 g of pituitary powder, 8‐10‐mg amounts of MTGF‐Pit were isolated. By 8 M urea, 0.1% SDS‐12.5% polyacrylamide gel electrophoresis analysis followed by Coomassie blue staining, this preparation was shown to be one major stained band. When assayed for growth effects on cells maintained in serum‐free medium, 5.1‐19.2 nM MTGF‐Pit half replaced the growth of MTW9/PL rat and MCF‐7 and T‐47D human mammary tumor cells in response to 2% to 10% serum. MTGF‐Pit shows mitogenic activity toward normal human diploid fibroblasts only at concentrations in excess of 2.5 × 10−4M, while rat fibroblasts are unresponsive even at this high concentration. From data available, we conclude that a mitogenic activity for epithelial‐type mammary cells has been isolated, and this growth factor appears to be a previously undetected acid‐ and heat‐stable activity that is highly abundant (estimated at 0.16% or more of the total dry weight of the pituitary powder). The isolated ovine MTGF‐Pit (3,900 ± 200 daltons) does not share the molecular weight of native prolactin (24,000 daltons), “cleaved” prolactin (16,000 daltons), or growth hormone (22,000 daltons), and by all tests applied cannot be replaced with other known hormones and purified growth factors. We conclude a potent new mammary tumor cell mitogenic activity

ISSN:0730-2312    

DOI:10.1002/jcb.240250404

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

年代:1984

数据来源: WILEY

摘要:

AbstractIn vivo clearance studies have indicated that the clearance of proteinase complexes of the homologous serine proteinase inhibitors α1‐proteinase inhibitor and anti‐thrombin III occurs via a specific and saturable pathway located on hepatocytes. In vitro hepatocyte‐uptake studies with antithrombin III‐proteinase complexes confirmed the hepatocyte uptake and degradation of these complexes, and demonstrated the formation of a disulfide interchange product between the ligand and a cellular protein. We now report the results of in vitro hepatocyte uptake studies with α1‐proteinase inhibitor‐trypsin complexes. Trypsin complexes of α1‐proteinase inhibitor were prepared and purified to homogeneity. Uptake of these complexes by hepatocytes was time and concentration‐dependent. Competition experiments with α1‐proteinase inhibitor, α1‐proteinase inhibitor‐trypsin, and antithrombin III‐thrombin indicated that the proteinase complexes of these two inhibitors arc recognized by the same uptake mechanism, whereas the native inhibitor is not. Uptake studies were performed at 37°C with125I‐α1‐proteinase inhibitor‐trypsin and analyzed by sodium dodecyl sulfate‐gel electrophoresis in conjunction with autoradiography. These studies demonstrated time‐dependent uptake and degradation of the ligand to low molecular weight peptides. In addition, there was a time‐dependent accumulation of a high molecular weight complex of ligand and a cellular protein. This complex disappeared when gels were performed under reducing conditions. The sole cysteine residue in α1‐proteinase inhibitor was reduced and alkylated with iodoacetamide. Trypsin complexes of the modified inhibitor were prepared and purified to homogeneity. Uptake and degradation studies demonstrated no differences in the results obtained with this modified complex as compared to unmodified α1‐proteinase inhibitor‐trypsin complex. In addition, the high molecular weight disulfide interchange product was still present on sodium dodecyl sulfate‐polyacrylamide gel electrophoresis of solubilized cells. Clearance and clearance competition studies with approteinase inhibitor‐trypsin, alkylated α1‐proteinase inhibitor‐trypsin, antithrombin III‐thrombin, and antithrombin III‐factor IXafurther demonstrated

ISSN:0730-2312    

DOI:10.1002/jcb.240250405

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

年代:1984

数据来源: WILEY

ISSN:0730-2312    

DOI:10.1002/jcb.240250401

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

年代:1984

数据来源: WILEY