bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selective regulation of β2‐adrenergic receptor gene expression by interleukin‐1 in cultured human lung tumor cells
Authors: Szentendrei Tibor , Lazar‐Wesley Eliane , Nakane Tokio , Virmani Mridulika , Kunos George 
Published: February 2005

AbstractThe regulation of β1‐ and β2‐adrenergic receptors (β1 AR and β2 AR) and receptor gene expression by interleukin‐1α (IL‐1α) was studied in cultured A549 human lung adenocarcinoma cells. The density and affinity of β1 AR and β2AR were analyzed by computerized curve fitting of 125I‐pindolol binding and its displacement by subtype selective antagonists. Steady state levels of receptor mRNAs were quantified by DNA excess solution hybridization assays. A549 cells in preconfluent cultures had fewer β1AR than β2AR (β1: 1.9 ± 0.3 vs. β2: 4.0 ± 0.5 fmol/mg protein, means ± SE), but lost most of their β2AR upon reaching confluency (β1: 2.7 ± 0.4, β2: 0.8 ± 0.3 fmol/mg). Incubation of preconfluent cells for 24 hr with 20 pM of human recombinant IL‐1α did not modify the density of either of the βAR subtypes. Similar incubations of confluent cells increased the density of β2AR from 0.8 ± 0.3 to 4.2 ± 0.9 fmol/mg, while the density of β1AR and the antagonist affinities of both receptors remained unaltered. The IL‐1α‐induced increase in β2AR density in confluent cells was antagonized in a concentration‐dependent manner by a recombinant protein antagonist of type I IL‐1 receptors (IC50: 0.2 nM). The IL‐1α‐induced increase in β2AR density was preceded by an increase in the steady state level of β2AR mRNA, while levels of β1AR mRNA remained unchanged. IL‐1α increased the stability as well as the rate of transcription of β2AR mRNA. These findings demonstrate for the first time that activation of type I IL‐1 receptors in A549 cells leads to a cell density‐dependent, selective upregulation of β2AR, and that the mechanism of this effect involves increased formation and stability of the β2AR message. © 1992 Wiley‐Liss, Inc.
Transforming growth factor‐β enhances calcitonin‐induced cyclic AMP production and the number of calcitonin receptors in long‐term cultures of human umbilical cord blood monocytes in the presence of 1,25‐dihydroxycholecalciferol
Authors: Mbalaviele Gabriel , Orcel Philippe , Bouizar Zhor , Jullienne Annick , De Vernejoul Marie Christine 
Published: February 2005

AbstractTransforming growth factor‐β (TGF‐β) is a multifunctional polypeptide, abundant in bone, that regulates both proliferation and differentiation of a wide variety of cells, but its role in osteoclast differentiation remains controversial. We have recently shown that long‐term cultures of human cord blood monocytes, in the presence of 1,25 dihydroxycholecalciferol (1,25‐(OH)2D3), give rise to cells that express two markers of the osteoclast phenotype, namely, the vitronectin receptor (VNR) and the calcitonin receptor (CTR). TGF‐β enhanced the proportion of cells expressing the VNR.In the present study, we investigated the effect of TGF‐β on the expression of CTR in cord blood monocytes cultured during 3 weeks in the presence of 1,25‐(OH)2D3. When added within the first 2 weeks of culture, TGF‐β (500 pg/ml) significantly decreased the cell protein content. TGF‐β alone did not stimulate basal cAMP production. The 10 nM‐sCT‐stimulated cAMP production was enhanced by increasing TGF‐β concentrations from 50 pg/ml to 1,000 pg/ml: for 500 pg/ml TGF‐β, it was 294 ± 28% vs. 140 ± 25% for control cultures (p < 0.01). The sCT dose‐response curves showed a higher cAMP production from 10−9 M to 10−7 M of sCT in the presence of 500 pg/ml TGF‐β than in control cultures. The increase was 325 ± 36% in the presence of TGF‐β and 195 ± 13% in the absence of TGF‐β, for 10−7 M sCT (p < 0.01). This effect of TGF‐β on cAMP production was not observed either when it was added to monocyte cultures the last day or 2 hours before the end of the culture or in MCF7, a human breast cancer cell line that expresses CTR. [125I]‐sCT binding studies performed on confluent cells showed similar Kd in control and TGF‐β‐treated cells. By contrast, the CTR number was significantly increased in the presence of TGF‐β: 6.1 ± 2 × 104 receptors per cell in control cultures and 28.8 ± 8.1 × 104 receptors per cell in TGF‐β‐treated cultures (p < 0,05). It is thus suggested that TGF‐β increases the number of CTR of these cells that have other features of preosteoclasts. The role of this cytokine on the process of osteoclast differentiation and in bone resorption is thus emphasized. © 1992 Wiley‐Liss, Inc.
Protein kinase C remains functionally active during TPA induced neuronal differentiation of SH‐SY5Y human neuroblastoma cells
Authors: Parrow Vendela , Nånberg Eewa , Heikkilä Jari , Hammerling Ulf , Påhlman Sven 
Published: February 2005

AbstractSH‐SY5Y human neuroblastoma cells can be induced to differentiate into a neuronal phenotype by treatment with 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA). In other cell systems, TPA treatment frequently leads to down‐regulation of protein kinase C (PKC). However, we now report that TPA‐treated and non‐treated SH‐SY5Y cells express PKC‐α, but not PKC‐β and PKC‐γ, mRNA. Furthermore, only a slight down‐regulation of the PKC‐α protein could be seen during prolonged treatment with 16 nM TPA, the concentration giving optimal differentiation. In contrast, a higher concentration of TPA (1.6 μM) results in a poor neuronal differentiation and a complete down‐regulation of PKC‐α. PKC‐α was rapidly translocated to the particulate fraction and remained membrane bound for at least 4 days during treatment with 16 nM TPA. In such cells a sustained increased level of the phosphorylated form of a 80,000 Dalton PKC‐substrate was found. In addition to this sustained augmented phosphorylation, administration of fresh TPA at day 4 caused a small but reproducible further increased level of phosphorylated substrate. When the PKC activity was measured by the histone phosphorylation assay a substantial fraction of the initial enzyme activity could still be detected after 4 days of TPA treatment. Taken together, the data demonstrate that PKC remains functionally active during TPA induced differentiation of SH‐SY5Y cells, which may suggest a continuous role for the enzyme during the differentiation process. © 1992 Wiley‐Liss, Inc.
Mechanism of action of amylin in bone
Authors: Tamura Tatsuya , Miyaura Chisato , Owan Ichiro , Suda Tatsuo 
Published: February 2005

AbstractAmylin is a 37 amino acid peptide produced mainly by β‐cells of the endocrine pancreas. Human amylin has 43% homology with human calcitonin gene‐related peptide (CGRP) and 13% homology with human calcitonin (CT). Amylin and CGRP have been reported to have CT‐like hypocalcemic activity in vivo. To investigate the role of amylin in bone, we examined the mechanisms of action of human amylin, CGRP, and CT in osteoclasts and osteoblasts. Both human amylin and CGRP inhibited 1α, 25‐dihydroxyvitamin D3 [1α, 25(OH)2D3]‐induced bone resorption in an organ culture system, and the potencies of the two peptides were similarly ∼60‐fold lower than that of human CT. Using a recently developed procedure for preparing large numbers of osteoclast‐like multinucleated cells (MNCs) formed in co‐cultures of mouse osteoblasts and bone marrow cells in the presence of 1α, 25(OH)2D3, we found that both human amylin and CGRP stimulated cAMP production in osteoclast‐like MNCs, but only at 60‐fold higher concentrations than human CT. Specific binding of [125I]‐human CT to osteoclast‐like MNCs was detected (dissociation constant, 3 × 10−8 M; binding sites, 3 × 107 per cell). To displace the bound [125I]‐human CT from osteoclast‐like MNCs, about 170‐fold higher concentrations of human amylin and CGRP were required. No specific bindings of [125I]‐CGRP to osteoclast‐like MNCs could be detected. Human CGRP stimulated cAMP production both in established mouse osteoblast‐like cells (KS‐4) and in mouse primary osteoblast‐like cells. Amylin was a weak agonist for cAMP production in KS‐4 cells. The increment in cAMP production induced by CGRP and amylin was abolished by the addition of human CGRP(8–37), a selective antagonist for CGRP receptors. CT did not stimulate cAMP production in KS‐4 cells. Amylin, but not CT, displaced the bound [125I]‐human CGRP from rat brain membranes. These results indicate that amylin binds not only to CT receptors in osteoclast‐like MNCs but also to CGRP receptors in osteoblasts. The relative potencies of these compounds to induce cAMP production was CT > amylin ≒ CGRP in osteoclast‐like MNCs and CGRP > amylin ≫ CT in osteoblast‐like cells. © 1992 Wiley‐Liss, Inc.
Insulin‐like growth factor binding protein (IGFBP‐3), an inhibitor of serum growth factors other than IGF‐I and ‐II
Authors: Liu L. , Delbé J. , Blat C. , Zapf J. , Harel L. 
Published: February 2005

AbstractOur results show that an insulin‐like growth factor binding protein, IGFBP‐3, purified from rat serum, is an inhibitor of chick embryo fibroblast (CEF) growth. It abolished DNA synthesis in CEF stimulated by IGF‐l as well as by human serum. Rat IGFBP‐3 and IDF45 (an inhibitory diffusible factor secreted by mouse cells) had the same activities, confirming that they have an intrinsic capacity to inhibit serum stimulation and may be considered as growth inhibitors. Our data show that inhibition by IGFBP‐3 of serum stimulation was not simply the result of its inhibition of IGF present in the serum: 1) While anti‐I lgG was able to completely inhibit stimulation induced by added IGF‐I, it did not decrease stimulation induced by 1% human serum. Anti‐IGF‐II IgG inhibited the stimulation induced by added IGF‐II, but only 25% decreased the stimulation induced by 0.7% serum. The percent inhibition was not significantly increased when the concentration of serum was decreased to 0.2%, which induced 140% stimulation of DNA synthesis; 2) stimulation by 0.2% serum was much more inhibited by IGFBP‐3 than by IgG anti IGF‐II; 3) after separation of IGF‐I and IGF‐II from serum by chromatography of acidified serum proteins on BioGel P150, the remaining serum proteins (with a molecular mass greater than 45 kDa) which were depleted in IGF‐I and ‐II (verified by RIA determination) still stimulated DNA synthesis, and this stimulation was 80% inhibited by IGFBP‐3. © 1992 Wiley‐Liss, Inc.
Quantitative fatty acid analyses in cultured porcine pulmonary artery endothelial cells: The combined effects of fatty acid supplementation and oxidant exposure
Authors: Hart C. Michael , Tolson J. Keith , Block Edward R. 
Published: February 2005

AbstractSupplemental fatty acids can modify the oxidant susceptibility of pulmonary artery endothelial cells (PAEC) in monolayer culture. In addition, in vivo dietary modifications have altered tissue and animal susceptibility to a variety of forms of oxidant stress. These modifications of oxidant injury have been attributed to changes in the numbers of fatty acid double bonds in cell lipids. We tested this hypothesis by incubating porcine PAEC in culture medium supplemented with either 0.1 mM oieic acid (18: 1ω9) or with an equivalent volume of ethanol vehicle alone (ETOH‐0.1%) for 3 h. After supplementation, PAEC were exposed to either oxidant stress, 100 μM hydrogen peroxide (H2O2) in Hanks' balanced salt solution (HBSS), or to control condition, HBSS alone, for 30 min. Supplemented PAEC were exposed to HBSS or H2O2 either immediately or 24, 48, or 72 h after supplementation. Supplementation with 18:1 protected PAEC from H2O2‐induced injury at all time points. The fatty acid composition of PAEC phospholipid (PL), triglyceride (TG), and free fatty acid (FFA) subclasses was determined using thin layer and gas chromatography. The PL fraction contained the majority of PAEC fatty acids, and H2O2 reduced the polyunsaturates in this fraction regardless of supplementation. Supplementation with 18:1 increased the 18:1 content of PAEC PL, TG, and FFA at all time points, modified other fatty acids to a lesser extent, but failed to alter the overall number of fatty acid double bonds at all time points. These results indicate that modification of double bond number does not fully explain the mechanisms by which changes in lipid composition can modulate oxidant injury. © 1992 Wiley‐Liss, Inc © 1992 Wiley‐Liss, Inc.
Use of peanut lectin and rat mammary stem cell lines to identify a cellular differentiation pathway for the alveolar cell in the rat mammary gland
Authors: Rudland Philip S. 
Published: February 2005

AbstractThe presence of the carbohydrate receptor for PNL has been used to identify the previously described morphological types of epithelial cell produced as the stem cell line rat mammary 25 (Rama 25) differentiates to casein secretory alveolar‐like cells in vitro. Thus when cultures of the epithelial stem cell line Rama 25 are treated with neuraminidase, fluorescently‐conjugated PNL fails to stain cuboidal cells, stains weakly grey cells, and stains strongly the surface of dark cells. When superconfluent cultures of Rama 25 are treated with dimethyl sulfoxide or retinoic acid and prolactin, estradiol, hydrocortisone, and insulin to induce differentiation to alveolar cells, PNL stains strongly the untreated surfaces of droplet cells and casein‐secreting vacuolated cells. PNL‐staining of the derivative cell lines with truncated cellular pathways, and quantitative binding of [125]‐labeled PNL to the cultured cells are consistent with this cellular staining pattern. The presence of the carbohydrate receptor for peanut lectin (PNL) has also been used to identify specific epithelial cell types in different mammary structure of the developing rat mammary gland, as they differentiate to casein secretory alveolar cells in vivo. Thus when different structures of the developing rat mammary gland are treated with neuraminidase, peroxidase‐conjugated PNL fails to stain histochemically the majority of epithelial cells in ducts, stains the cytoplasm of the majority of epithelial cells in terminal end‐buds (TEBs), and stains strongly the luminal surfaces of the majority of epithelial cells in alveolar buds (ABs). PNL also stains the untreated luminal surfaces of alveolar cells, whether or not the cells can be stained with a monoclonal antibody to rat β‐casein. Stimulation of mammary differentiation by an analogue of ethyl retinoate or by perphenazine causes cells in end‐buds to bind PNL without the necessity for their desilylation similar to that seen in casein secretory alveoli of lacting rats. In conclusion the different interconvertin cell types of Rama 25 which form a pathway to casein‐secretory cells in vitro are thus equated with recognisable epithelail cells types in vivo. These results suggest that casein‐secretory cells in invo are generated by similar successive interconversions between the major epithelial cell types present in the different mammary structures in the order: ducts, TEBs, ABs, alveoli, and secretory alveoli. © 1992 Wiley‐Liss, Inc.
Hepatocyte growth factor induces calcium mobilization and inositol phosphate production in rat hepatocytes
Authors: Baffy György , Yang Lijun , Michalopoulos George K. , Williamson John R. 
Published: February 2005

AbstractThe effects of hepatocyte growth factor (HGF) on intracellular Ca2+ mobilization were studied using fura‐2‐loaded single rat hepatocytes. Hepatocytes microperfused with different amounts of HGF responded with a rapid concentration‐dependent rise in the cytosolic free Ca2+ concentration with a maximum increase of 142% at 80 ng/ml of HGF. The lag period of the Ca2+ response was decreased with increasing HGF concentrations, being 64 ± 12 s, 42 ± 6 s, and 14 ± 2 s, respectively, with 8, 20, and 80 ng/ml of HGF. The detailed pattern of Ca2+ transients, however, was variable. Out of 16 cells tested using 20 ng/ml of HGF, 68% showed sustained oscillatory responses, whereas other cells showed a sustained increase in the cytosolic‐free Ca2+ upon exposure to HGF, which was dependent on the presence of extracellular Ca2+. HGF also induced Ca2+ entry across the plasma membrane. Mobilization of Ca2+ by HGF was accompanied by a rapid accumulation of inositol 1,4,5‐trisphosphate (Ins 1,4,5‐P3). The effects of HGF and epidermal growth factor (EGF) were comparable and partly additive for Ins 1,4,5‐P3 production and for the sustained phase of Ca2+ mobilization. Preincubation of cells with 10 μM of genistein to inhibit protein tyrosine kinases abolished the HGF‐induced Ca2+ response and also inhibited HGF‐induced Ins 1,4,5‐P3 production in rat liver cells. These data indicate that early events in the signal transduction pathways mediated by HGF and EGF have in common the requirements for tyrosine kinase activity, Ins 1,4,5‐P3 production, and Ca2+ mobilization. © 1992 Wiley‐Liss, Inc.
Characterization of interactions between CCK‐33 and CCK receptors in isolated dispersed pancreatic acini
Authors: Hosotani Ryo , Chowdhury Parimal , Doi Ryuichiro , Rayford Phillip L. 
Published: February 2005

AbstractIn isolated dispersed pancreatic acini, we have characterized the interactions between cholecystokinin (CCK) and CCK receptors by simultaneously measuring CCK‐33 immunoreactivity and CCK bioactivity. Incubation of acinar cells with CCK‐33 at cell density of 0.2–0.3 mg acinar protein per ml resulted in stimulation of amylase release concomitant with significant and time‐dependent decrease of the immunoreactive CCK. With L‐364,718 (0.1 μM), a specific CCK receptor antagonist, immunoreactive CCK levels in the media were not significantly altered during incubation; however, CCK‐stimulated amylase release was almost completely abolished (94% inhibition). Vasoactive intestinal peptide (1 nM) significantly potentiated CCK stimulated amylase release without affecting immunoreactive CCK in the media. Insulin (167 nM) did not effect the CCK stimulated amylase release or immunoreactive CCK in the media. Incubation of acinar cells with CCK‐33 at 4°C did not affect the levels of immunoreactive CCK; however, a significant change in levels of immunoreactive CCK were found at 37°C at 90 min. Incubation of cell free medium with CCK‐33 in the presence or absence of secreted enzymes revealed no changes in CCK immunoreactivity in the medium at 90 min. Addition of bacitracin in the incubation media did not affect the CCK immunoreactivity or bioactivity. These findings indicate that in isolated rat pancreatic acini, CCK‐33 stimulates amylase release through a receptor that is specifically blocked by L‐364,718. Specificity of the interactions of CCK‐33 with acinar cells in the media appears to be receptor‐mediated and time‐ and temperature‐dependent. © 1992 Wiley‐Liss, Inc.
In vitro effect of extracellular AMP on MCF‐7 breast cancer cells: Inhibition of glycolysis and cell proliferation
Authors: Hugo Ferdinand , Mazurek Sybille , Zander Ute , Eigenbrodt Erich 
Published: February 2005

AbstractMCF‐7 human breast cancer cells propagated in vitro were treated with adenosine derivatives added to the culture medium. The effects on cell proliferation, glycolysis, and glutaminolysis were investigated. Of all adenosine derivatives tested, AMP was the most efficient inhibitor of cell proliferation. In AMP‐treated cells, DNA synthesis decreased, whereas RNA and protein syntheses rose normally with time. In terms of carbohydrate metabolism, lactate production from glucose was drastically reduced; therefore, most of lactate produced must have been derived from glutamine. Increase in the enzyme activities involved in glutatmate degradation and in the malate‐aspartate shuttle were observed. In contrast, actual glycolytic flux rates declined, whereas key glycolytic enzyme activities increased. Metabolites such as fructose 1,6‐bisphosphate and pyruvate accumulated in AMP‐arrested cells. Based on the lowered NAD level in the AMP‐treated cells, lactate dehydrogenase, but not malate dehydrogenase, was impaired; thereby the whole of glycolysis was inhibited. In compensation, glutamine catabolism was increased. NAD concentrations fell drastically because of the known inhibition of P‐ribose‐PP synthesis through heightened intracellular AMP levels. A hypothetical metabolic scheme to explain these results and to show how extracellular AMP may influence carbohydrate metabolism and cell proliferation is presented. © 1992 Wiley‐Liss, Inc.
Partial characterization of skeletal myoblast mitogens in mouse crushed muscle extract
Authors: Chen Gang , Quinn Lebris S. 
Published: February 2005

AbstractWe have utilized a model system to investigate myotrophic factors released by normal adult mouse muscles following a crush injury. We found that saline extracts from gently crushed mouse muscles (CME) contain potent mitogenic activities which act on primary newborn mouse myoblast cultures, as well as on mouse C2 cells, a mouse myoblast cell line. We compared the activity of CME on mouse myoblasts with that of basic fibroblast growth factor (bFGF) and insulin‐like growth factor I (IGF‐I), two growth factors known to be mitogenic for primary myoblasts (Allen, Dodson, and Lutein: Exp. Cell. Res., 152:154–160, 1984; DiMario and Strohman: Differentiation, 39:42–49, 1988; Allen and Boxhorn: J. Cell. Physiol., 138:311–315, 1989; Dodson, Allen, and Hossner: Endocrinology, 117:2357–2363, 1985; Florini and Magri: Am. J. Physiol., 256:C701–C711, 1989). We found that CME could act in an additive fashion to saturating doses of bFGF to increase proliferation in myoblast cultures. Additionally, CME acted additively to the combination of saturating amounts of bFGF and IGF‐I on both C2 and primary myoblast cultures. We also examined additivity of CME with the combination of saturating doses of bFGF, IGF‐I, transferrin (Tf), platelet‐derived growth factor (PDGF), epidermal growth factor (EGF), adrenocorticotrophin (ACTH), and macrophage colony‐stimulating factor (M‐CSF). Our data indicate that CME contains Tf, as well as one or more uncharacterized mitogens for myoblasts which are distinct from Tf, the IGFs, bFGF, EGF, PDGF, M‐CSF, and ACTH. These uncharacterized mitogens may act independently of known growth factors to stimulate myoblast proliferation, or may act through modulation of known growth factor activities. © 1992 Wiley‐Liss, Inc.
Human aortic endothelial cells express the type I but not the type II receptor for interleukin‐1 (IL‐1)
Authors: Akeson Ann L. , Mosher Laura B. , Woods Connie W. , Schroeder Kendra K. , Bowlin Terry L. 
Published: February 2005

AbstractEndothelial cells (EC) are very responsive to the proinflammatory cytokine inter‐leukin‐1 (IL‐1). EC are induced by IL‐1 to secrete chemotactic factors and to increase expression of cell surface adhesion molecules leading to increased leukocyte adhesion. Activated EC turther contribute to the inflammatory response by secreting additional cytokines. IL‐1 interacts with EC through high‐affinity cell‐surface receptors. However, the low number of receptors present on EC has made characterization difficult. Further, recent evidence has suggested diversity in the responses of EC from different regions of the vascular system. Interested in the effect of IL‐1 on early atherosclerotic lesion formation, we have characterized the IL‐1 receptors on human aortic endothelial cells (HAEC). Using a direct binding assay, we found that HAEC have 1,000–3,000 IL‐1 receptors per cell and bind IL‐1α with a Kd of 3.5 × 10−10 M. We found that a monoclonal antibody specific for the type I receptor completely blocks IL‐1α binding. The blocking antibody also completely inhibits the IL‐1 induced increase in intracellular adhesion molecule 1 (ICAM‐1) expression by HAEC. Using solution hybridization and ribonuclease protection with an antisense probe, a sensitive method for detection of low abundance mRNA species we found that HAEC as well as human umbilical vein EC (HUVEC) have significant levels of mRNA for the type I IL‐1 receptor. To test whether HAEC might also contain transcripts for the type II IL‐1 receptor, we compared levels of mRNAs by polymerase chain reaction (PCR) amplification of cDNAs reverse‐transcribed from total RNA. We found only transcripts for the type I receptor and not the type II receptor in HAEC. Based on this data, we conclude that aortic endothelial cells respond to IL‐1 through the type I receptor. © 1992 Wiley‐Liss, Inc.