bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of AP‐3 enhancer activity during hematopoietic differentiation
Authors: Adler Victor , Kraft Andrew S. 
Published: February 2005

AbstractPhorbol ester treatment of the human leukemic cell line U937 induces macrophage differentiation over 24–28 hr. This differentiation is mediated by the activation and/or repression of specific gene transcription by proteins, enhancer binding factors, that bind to the DNA upstream of the start site of transcription. We find that differentiation of U937 cells induced by phorbol eters and bryostatin 1, activators of protein kinase C, and the phosphatase inhibitor, okadaic acid, stimulates transcription from an enhancer sequence which contains multimerized AP‐3 binding sequences but not from one that contains multimerized AP‐2 binding motifs. Electrophoretic mobility shift assays (EMSA) demonstrate that AP‐3 DNA binding activity peaks at 24 hr, remains elevated for 24 hr, and then decreases thereafter. Southwestern blotting demonstrates that the AP‐3 enhancer sequence binds to a 48 kDa protein present in these leukemic cells. Because the AP‐3‐oligomer also contains an overlapping NF‐kB‐like site, the role of NF‐kB proteins in regulating transcription from this multimerized oligonucleotide was investigated. Transfection of U937 cells with NF‐kB family members demonstrated activation of AP‐3‐mediated transcription by rel A but little effect induced by NFKB1 and c‐rel. It is unlikely, however, that phorbol ester‐induced transcription from this AP‐3 sequence is solely mediated by this NF‐kB family member since treatment of U937 cells with antisense rel A oligodeoxynucleotides did not block phorbol ester‐mediated transcription from the AP‐3 site. These data demonstrate that AP‐3, but not AP‐2 sequences, functions to activate mRNA transcription during phorbol ester‐induced hematopoietic differentiation and suggests a complex interaction between NF‐kB and AP‐3 proteins in the regulation of this enhancer element. © 1995 Wiley‐Liss, Inc.
Effects of hypotonic and hypoionic media on drug pumping by P‐glycoprotein expressed in epithelial and nonepithelial cell lines
Authors: Ambasch Karina , Cabantchik Z. Ioav , Slotki Itzchak N. 
Published: February 2005

AbstractThe effects of anisotonic and anisoionic media on the drug‐pumping function of P‐glycoprotein (Pgp) were studied in epithelial and nonepithelial cells. We used HT‐29 colon cells (HT‐29/Pgp−) induced to express Pgp and MDR phenotype (HT‐29/Pgp+) and NIH3T3 (3T3/Pgp−) cells which were stably transfected with human MDR1 DNA (3T3/Pgp+). Intracellular concentrations of rhodamine 123 (R‐123) preloaded into cells were monitored as a function of time by fluorescence imaging microscopy, while cells were superfused with media of different tonicity and/or ionic strength. Efflux was analyzed by a single exponential decay function. In all media tested efflux was considerably higher in Pgp+ than Pgp− cells. In both HT‐29 and 3T3 cells loaded with dye in isotonic conditions, dye efflux was not significantly different whether it was measured in isoionic‐isotonic (130 mM NaCI, 300 mOsm), hypoionic‐isotonic (87 mM NaCI), or hypoionic‐hypotonic (200, 150, or 100 mOsm) media throughout the entire experiment or whether the media were changed during the experiment. Similar results were obtained when cells were preincubated and preloaded with dye under hypotonic conditions. Under extreme hypotonic and hypoionic challenge (changing from 130 mM NaCI‐300 mOsm to 43 mM NaCI‐100 mOsm medium), 3T3 cells, but not HT‐29 cells, underwent marked shape and size changes which reduced R‐123 cell‐associated fluorescence. The changes were most conspicuous in Pgp+ cells, possibly reflecting a Pgp effect on the osmotic or osmoregulatory properties of the cells. However, drug‐pumping activity remained essentially unimpaired even under the most extreme hypotonic/hypoionic conditions. © 1995 Wiley‐Liss, Inc.
Ca2+‐Atpase inhibitor, cyclopiazonic acid, releases Ca2+ from intracellular stores in rbl‐2h3 mast cells and activates a Ca2+ influx pathway that is permeable to sodium and manganese
Authors: Falcone Daniel , Fewtrell Clare 
Published: February 2005

AbstractCyclopiazonic acid has been reported to inhibit the Ca2+‐ATPase of intracellular calcium stores in some nonexcitable cell types, such as myeloid cells and lymphocytes. The present study examines the effects of cyclopizonic acid on rat basophilic leukemia (RBL) cells, a mucosal mast cell line. Addition of cyclopiazonic acid to fura‐2‐loaded RBL cells evoked a biphasic increase in free ionized intracellular calcium. Release of stored calcium accounted for the first phase of this response. The second phase was determined to be calcium entering through an influx pathway activated by cyclopiazonic acid. The influx pathway was selective for calcium, But was somewhat permeable to manganese. However, in a Ca2+‐free solution containing EGTA, sodium ions permeated freely. This influx pathway appears to be identical to that which is activated by antigen, the physiological stimulus to the cells. Cyclopiazonic acid also induced secretion when combined with the phorbol ester 12‐0‐tetradecanoyl phorbol 13‐acetate, which activates protein kinae C. © 1995 Wiley‐Liss, Inc.
Induction of intercellular adhesion molecule‐1 by monocyte adhesion to endothelial cells in human culture system
Authors: Combe Christian , Duplàa Cecile , Couffinhal Thierry , Moreau Catherine , Bonnet Jacques 
Published: February 2005

AbstractIncreased monocyte adhesion to the endothelial lining of blood vessels by cytokine‐inducible adhesion proteins is a crucial event in inflammatory processes. Moreover, adherence is known to induce cytokine gene expression, suggesting a possible positive feedback mechanism. Therefore, we determined whether monocyte adhesion to endothelial cells (ECs) amplifies their adhesion by inducing intercellular adhesion molecule 1 (ICAM‐1), and whether such positive feedback mechanism could be mediated by secretion of interleukin‐1 (IL‐1). Using monocyte‐EC couples obtained after monocyte adhesion to ECs, and methods of quantitative polymerase chain reaction and immunofluorescence flow cytometry, we showed a biphasic increase of ICAM‐1 mRNA content (2 and 16 hours) and a time‐dependent increase of cell surface expression of ICAM‐1, mainly on ECs, and couple adhesiveness, after monocyte adhesion to ECs. Anti‐ICAM‐1 monoclonal antibody inhibited 63% of the enhancement of adhesiveness induced on monocyte‐EC couples by previous monocyte adhesion, suggesting that monocyte adhesion to ECs induces an increase of couple adhesiveness which is partially dependent on the ICAM‐1 pathway. The early ICAM‐1 mRNA induction was associated with a fast induction of IL‐1b̃ mRNA and a 7.7‐fold increase in IL‐1b̃ protein in supernatant. However, 30% of this 2‐hour ICAM‐1 mRNA peak was abolished by recombinant soluble human IL‐1 receptor, suggesting that the early ICAM‐1 overexpression was partially mediated by IL‐1b̃, and could be induced directly by adherence. The second ICAM‐1 mRNA peak was accompanied by a marked increase in IL‐1b̃ mRNA and protein secretion (2.6 ng/ml). The binding to ICAM‐1 did not appear to directly stimulate IL‐1b̃ synthesis. These results indicate that monocyte adhesion to endothelial cells appears to stimulate their own recruitment via induction of ICAM‐1 thereby constituting a self‐perpetuating positive feedback system. © 1995 Wiley‐Liss, Inc.
Secretion of plasminogen activator and lysosomal enzymes from mouse skeletal muscle: Effect of denervation
Authors: Von Steyern Fredrik Vult , Josefsson Jan‐Owe 
Published: February 2005

AbstractLevels of hydrolytic enzymes increase in skeletal muscle after denervation and their activities in the extracellular matrix appear to be important for interaction between muscle and nerve. Using enzymatic assays for b̃‐glucuronidase, b̃‐galactosidase, and plasminogen activator, we show that secretion of these enzymes from mouse skeletal muscle increases after denervation and that drugs interfering with the secretory pathway or the reuptake of enzymes modulate this release. Thus, brefeldin A inhibited secretion of plasminogen activator activity and mannan increased secreted amounts of b̃‐glucuronidase, but not of b̃‐galactosidase, in denervated muscle. In innervated muscle, brefeldin A decreased secreted activity of plasminogen activator, but mannan had no effect on secretion of either b̃‐glucuronidase or b̃‐galactosidase. Furthermore, secretion of plasminogen activator was temperature dependent. These observations, together with previous studies, suggest that secretion of hydrolytic enzymes from adult skeletal muscle may be of physiological significance in nerve‐muscle communication. © 1995 Wiley‐Liss, Inc.
Two nuclear proteins in tracheal epithelial cells are recognized by antibodies specific to a squamous differentiation marker, sprl
Authors: Tesfaigzi Johannes , An Gang , Wu Reen , Carlson Don M. 
Published: February 2005

AbstractIn cell‐free translations of RNA from primary cultures of pig trachea surface epithelial cells we observed that a mRNA encoding a 20kDa proline‐rich protein (sPRP) was dramatically induced during culturing (Tesfaigzi et al., 1990, Biochem. Biophys. Res. Commun., 172:M1304–1309). This mRNA was no detected in tracheal tissue or in epithelial cells prior to culturing. Antisera were raised to synthetic peptide sequences corresponding to 23 amino acids on the C‐terminus (C23‐antiserum) and 29 amino acids on the N‐terminus (N29 antiserum) of sPRP. On Western blot analysis, C23 antiserum reacted with a 20 kDa protein in cytosolic extracts from pig tracheal cells maintained in culture for 4 days. The reaction with the 20 kDa protein was inhibited by adding C23 peptide. Two nuclear proteins (66 and 70 kDa) obtained by micrococcal nuclease treatment of tracheal cell nuclei were detected on Western blots with C23 antiserum. These proteins were present in cells both before and after culturing. Sucrose gradient fractionation indicated that these nuclear proteins are associated with chromatin. Small amounts of the 66 and 70 kDa proteins were obtained from nuclear matrix fractions. These nuclear proteins also reacted with N29 antiserum. Since these proteins share similar epitopes with the N‐ and C‐termini of sPRP, it is likely that the 20 kDa protein (sPRP) is part of these proteins. However, purification of the nuclear proteins followed by an amino acid sequence analysis is necessary to clarify whether sPRP is part of these proteins. © 1995 Wiley‐Liss, Inc.
Synergistic interaction of interleukin‐1β and growth factors in primary cultures of rat aortic smooth muscle cells
Authors: Bourcier Todd , Dockter Michael , Hassid Aviv 
Published: February 2005

AbstractActivated macrophages release cytokines and growth factors that may contribute to the growth of vascular smooth muscle cells in injured blood vessels. In the present study, we investigated the interactions between interleukin‐1b̃ (IL‐1b̃) and basic fibroblast growth factor (FGF‐2) in primary rat aortic smooth muscle cells, relative to their effects on DNA synthesis and cell proliferation. We report that femtomolar levels of IL‐1b̃, which alone were non‐mitogenic or weakly mitogenic, synergistically increased FGF‐2‐induced [3H]thymidine incorporation and cell proliferation. The potentiating effect of IL‐1b̃ extended to PDGF‐AB and EGF, but not to IGF‐1‐induced thymidine incorporation. An antagonist of the IL‐1 receptor, IL‐1ra, blocked the co‐mitogenic effect of IL‐1b̃. Stimulation of cells with FGF‐2 and IL‐1b̃ increased both DNA content and proliferation, an observation that was consistent with the thymidine incorporation experiments. An inhibitor of NO synthase, N5‐iminoethyl L‐ornithine (L‐NIO), did not block the co‐mitogenic effect of IL‐1b̃, despite effective inhibition of NO synthase activity, suggesting that the synergistic interaction between IL‐1b̃ and FGF‐2 was independent of the NO/cGMP pathway. The mechanism of co‐mitogenesis appeared to be independent of the intermediacy of PDGF‐AA, IL‐6, and prostanoids, and was not associated with increased levels of c‐fos mRNA, FGF receptor‐1 protein, or FGF‐2‐induced early and delayed tyrosine phosphorylation events. We conclude that IL‐1b̃ interacts with FGF‐2 to amplify the proliferation of primary rat aortic smooth muscle cells, an effect that may be important in vascular smooth muscle cell proliferation following vascular injury. © 1995 Wiley‐Liss, Inc.
Tenascin‐C induction by the diffusible factor epidermal growth factor in stromal‐epithelial interactions
Authors: Sakai Takao , Ohta Masatsugu , Furukawa Yusuke , Saga Yumiko , Aizawa Shinichi , Kawakatsu Hisaaki , Saito Masaki 
Published: February 2005

AbstractTenascin‐C, a six‐armed extracellular matrix glycoprotein, is expressed in a temporally and spatially restricted pattern during carcinogenesis and invasion or metastasis of carcinoma cells in association with stromal‐epithelial interactions. The human epidermoid carcinoma‐derived cell lines, A431 and HEp‐2, which do not express tenascin‐C by themselves in vitro, do express tenascin‐C after transplantation into nude mice, and transforming growth factor β1 (TGF‐β1) induces them to express tenascin‐C in vitro. Epidermal growth factor (EGF) induced tenascin‐C in these cells more effectively (about 3.5‐fold greater) than did TGF‐β1. Hepatocyte growth factor (HGF) and platelet‐derived growth factor (PDGF) had little effect on the induction of tenascin‐C. EGF also induced other extracellular matrix components, fibronectin and laminin. Tenascin‐C was also induced when the carcinoma cells were co‐cultured with embryonic fibroblasts from mice which were homozygous for a null mutation in the tenascin‐C gene, or when the conditioned medium from these cells was added. The induction of tenascin‐C in the co‐culture was reduced by treating the cells with antibodies against EGF or its receptor. The addition of EGF caused both cell types to disrupt their cytoskeleton and focal contacts as evidenced by the loss of stress fibers and vinculin plaques. EGF did neither induce tenascin‐C nor affect the morphology in tenascin‐C‐nonproducing A549 carcinoma cells, which did not produce tenascin‐C after transplantation. Thus, EGF induces tenascin‐C in tenascin‐C‐nonproducing human carcinoma cells through EGF receptors. Furthermore, in stromalepithelial interactions, the diffusible factor EGF participates in the induction of human tenascin‐C in these cells through EGF receptors. © 1995 Wiley‐Liss Inc.
Increased tumorigenicity in the human pancreatic cell line MIA PaCa‐2 Is associated with an aberrant regulation of an IGF‐1 autocrine loop and lack of expression of the TGF‐β type RII receptor
Authors: Freeman James W. , Mattingly Cynthia A. , Strodel William E. 
Published: February 2005

AbstractThe growth characteristics associated with tumorigenicity were determined in clones of MIA PaCa‐2 and PANC‐1 pancreatic carcinoma cells. MIA PaCa‐2 cells differed from PANC‐1 cells in that they rapidly formed tumors in nude mice, formed colonies more rapidly and formed larger colonies in soft agar, and were cloned more efficiently when seeded at low density. MIA PaCa‐2 cells but not PANC‐1 cells were stimulated to escape quiescence and undergo DNA synthesis with nutrient media lacking growth factors. Both cell lines were stimulated to proliferate with serum‐free media containing EGF, transferrin, and insulin. Antibody neutralization assays indicated that an IGF‐1 autocrine loop was required for the nutrient stimulation of growth in MIA PaCa‐2 cells and for the growth‐factor stimulation in both MIA PaCa‐2 and PANC‐1 cells. Both cell lines were stimulated to proliferate with exogenous IGF‐1 in basal media; this stimulation was specifically blocked by antibodies to IGF‐1 or its receptor. MIA PaCa‐2 and PANC‐1 cells expressed similar levels of IGF‐1 receptor mRNA and showed similar binding kinetics in receptor binding assays. In contrast to PANC‐1 cells, MIA PaCa‐2 cells were insensitive to TGF‐β1 and did not express TGF‐β receptor type II. The results suggest that the growth‐factor independence is representative of a more tumorigenic phenotype. We hypothesize that growth‐factor independence of MIA PaCa‐2 cells is mediated by an aberrant regulation of an IGF‐1 autocrine loop. A decreased regulation of this IGF‐1 loop may be potentiated by loss of response to TGF‐β. © 1995 Wiley‐Liss Inc.
Retinoic acid nuclear receptor β inhibits breast carcinoma anchorage independent growth
Authors: Li Xiao‐Su , Shao Zhi‐Ming , Sheikh M. Saeed , Eiseman Julie L. , Sentz Dorothy , Jetten Anton M. , Chen Jian‐Chyi , Dawson Marcia I. , Aisner Seena , Rishi Arun K. , Gutierrez Peter , Schnapper Lauren , Fontana Joseph A. 
Published: February 2005

AbstractRetinoids modulate cellular proliferation and mediate gene function through a series of nuclear receptors. The retinoic acid nuclear receptor β (RARβ) plays an important role in the differentiation of a number of cell types. We now demonstrate that RARβ expresion is confined to normal mammary tissue and is not expressed in either immortalized normal or malignant cell lines. Treatment of RARβ‐transfected MDA‐MB‐231 cells with 1 μM all‐trans‐retinoic acid (RA) significantly inhibited monolayer growth of the cells which express recombinant RARβ. RARβ‐expressing MDA‐MB‐231 cells formed significantly smaller and fewer colonies soft agar than the mock‐transfected cells. Addition of 1 μM RA stimulated colony size and number in the RARβ‐transfected MDA‐MB‐231 cells. In contast to the RARβ‐expressing cells, colony formation by the RARβ‐expressing cells was similar to the mock‐transfected controls and the addition of 1 μM RA to the RARα‐transfected cells inhibited colony formation. While demonstrating decreased colony formation in agar, RARβ‐expressing MDA‐MB‐231 cells failed to exhibit decreased growth in SCID mice. Our results show that RARβ functions as a negative regulator of growth in breast epithelial cells. In addition, the growth of these cells is differentially regulated by RARα and RARβ which is most likely the result to the modulation of different genes. © 1995 Wiley‐Liss Inc.
Clonal heterogeneity of the sensitivity of human colon carcinoma cell lines to TGFβ isoforms
Authors: Zhou Guo‐Hao K. , Sechrist Gwendolyn L. , Brattain Michael G. , Mulder Kathleen M. 
Published: February 2005

AbstractSpontaneously arising, TGFβ1‐resistant colonies were isolated directly from the soft agarose plates of MOSER human colon carcinoma cells grown in the presence of TGFβ1 but in the absence of serum. The colonies were cloned by limiting dilution and screened in a monolayer proliferation assay for sensitivity to TGFβ1 and TGFβ2 isoforms. Cell clones selectively sensitive or resistant to these isoforms in the growth inhibition assay displayed similar differential sensitivities to TGFβ isoforms for production of the extracellular matrix proteins laminin and fibronectin, as well as for the expression of the colon cell differentiation marker carcinoembryonic antigen. Differential receptor binding profiles for TGFβ1 and TGFβ2 were observed among the clones. The isolation of cell clones selectively resistant or sensitive to TGFβ isoforms as well as the identification of differential receptor binding profiles among the clones indicate the heterogeneity of TGFβ responsiveness that exists naturally in human colon tumor cells and stress the importance of defining mechanisms underlying differential responsiveness to TGFβ isoforms. © 1995 Wiley‐Liss Inc.
Ornithine decarboxylase activity is associated with proliferation but not with T3‐induced differentiation of Caco‐2 cells
Authors: Jumarie Catherine , Malo Christiane 
Published: February 2005

AbstractOmithine decarboxylase (ODC) activity and polyamine (putrescine, spermidine, spermine) concentrations were measured in parallel in enterocyte‐like Caco‐2 cells maintained under various culture conditions. ODC activity was maximal at the begining of the exponential growth phase, decreasing dramatically thereafter to a negligible level at confluency (day 9). Kinetic studies performed on day 3 revealed the presence of a single enzyme with a Km around 200 μM and a Vmax of about 2 nmol CO2 released/h/mg protein. Similar values were obtained in both serum‐supplemented and transferrin/selenium (TS)‐defined culture media, indicating that ODC kinetic parameters are not affected by any factors present in serum. Polymine concentrations were maximal on day 5. By day 9, they returned to initial levels and remained at these fairly high values until day 21. Since we have previously shown (Jumarie and Malo, 1994, In Vitro Cell. Dev. Biol., 30A:753–760) that triiodothyronine (T3) stimulates differentiation but not proliferation of Caco‐2 cells maintained in TS‐defined medium, we investigated if it induces differentiation by a polyamine‐dependent mechanism. Short‐ and long‐term measurements revealed similar ODC activity and polyamine levels whether T3 was present or not in the culture medium. These results clearly demonstrate that polyamine synthesis is more likely to be associated with Caco‐2 cell proliferation, and that the T3 effect on Caco‐2 cell differentiation does not involve polyamine biosynthesis. Moreover, our data show that ODC activity is not solely regulated by intracellular polyamine concentration. © 1995 Wiley‐Liss Inc.