bluuebunny/crossref_metadata_2025_split huggingface dataset:
Receptor binding and mitogenic effects of insulin and insulinlike growth factors I and II for human myeloid leukemic cells
Authors: Pepe Michael G. , Ginzton Nancy H. , Lee Philip D. K. , Hintz Raymond L. , Greenberg Peter L. 
Published: February 2005

AbstractInsulin and insulinlike growth factors I and II (IGF‐I and IGF‐II) influence mesodermal cell proliferation and differentiation. As multiple growth factors are involved in hemopoietic cell proliferation and differentiation, we assessed the receptor binding and mitogenic effects of these peptides on a panel of mesodermally derived human myeloid leukemic cell lines. The promyelocytic cell line HL60 had the highest level of specific binding for these 125I‐labeled ligands, with lower binding to the less differentiated myeloblast cell line KG1 and undifferentiated blast variants of these cell lines (HL60blast, KG1a). Insulin binding affinity and receptor numbers were reduced significantly by chemically induced granulocytic differentiation of HL60 cells and was unchanged following induced monocytic differentiation. No substantial alteration in IGF‐I or ‐II binding occurred with induced HL60 cell differentiation. Insulin and IGF‐I demonstrated cross competition for receptor binding and down‐regulated their homologous receptors without detectable cross modulation of the heterologous receptors on HL60 cells. IGF‐I and insulin increased HL60 cell proliferation, as assessed by 3H‐thymidine uptake, IGF‐I> insulin. IGF‐I binding and mitogenic effects were blocked by the monoclonal anti‐IGF‐I receptor antibody IR3, indicating that IGF‐I‐induced proliferative effects were mediated via its homologous receptor. In contrast, insulin binding and mitogenesis displayed blocking by both anti‐IGI‐I and anti‐insulin receptor antibodies, indicating mediation of its activity through both receptors. These data demonstrate specific binding and mitogenic interactions between insulin, IGFs, and hemopoietic cells which are associated with their state of differentiation.
Effect of hypertonicity on hexose transporter regulation in chicken embryo fibroblasts
Authors: Tillotson Loyal G. , Isselbacher Kurt J. 
Published: February 2005

AbstractThe regulation of hexose transporters of cultured fibroblasts was investigated by exposing chicken embryo fibroblasts (CEF) to hypertonic culture medium, a condition known to enhance hexose transport activity. The effects of hypertonicity and the role of protein synthesis were examined with CEF in the basal (glucose fed) and transport enhanced (glucose starved) states. Glucose‐fed CEF exposed to hypertonic conditions developed four‐fold enhancement of hexose transport activity within 4 hrs; this declined in the following 20 hrs to a level slightly higher than the fed control. Protein synthesis was required in part for this effect, since the presence of cycloheximide during hypertonic exposure of fed CEF blocked the increase in of transport by almost 50%. Although the increased transport produced by glucose starvation was not further enhanced by hypertonicity, hypertonic treatment of starved CEF during glucose refeeding largely prevented the loss of transport acitivity to the basal, fed state. The hypertonic effects were concentration dependent (240mOsm optimal) and could be elicited with NaCl, KCl, or sucrose. Hypertonic treatment typically led to a greater than 50% decline in the incorporation of [3H]leucine into acid‐insoluble fractions. The changes in transport were evident at the plasma membrane level, and studies of membrane vesicles prepared from hypertonically treated fed CEF showed a doubling of both [3H]cytochalasin B binding and the Vmax of D‐glucose transport. These findings indicate that exposure of CEF to hypertonic conditions had some effects similar to those produced by glucose starvation and suggest that protein synthesis is to some extent involved in the regulation of hexose transporters in CEF.
Isoprenylated proteins in cultured cells: Subcellular distribution and changes related to altered morphology and growth arrest induced by mevalonate deprivation
Authors: Maltese William A. , Sheridan Kathleen M. 
Published: February 2005

AbstractIn the presence of lovastatin (mevinolin), an inhibitor of endogenous mevalonate synthesis, C1300 murine neuroblastoma cells incorporated (2‐14C)mevalonate into several discrete polypeptides that were separable by SDS‐PAGE. The electrophoretic pattern of the labeled proteins did not vary substantially when cells were homogenized with Ca++, Mg++, high concentrations of NaCl or phosphatase inhibitor, or when cells were lysed immediately in trichloroacetic acid. When cells that had been prelabeled with (14C)mevalonate were incubated with lovastatin and simultaneously deprived of exogenous mevalonate, there was a 50–60% decline in the concentration of protein‐bound isoprenoid label within 17 h. In contrast, there was little change in the radioactivity in the sterol, dolichol, or ubiquinone fractions. The time course of the decline in mevalonate‐derived label in cellular polypeptides paralleled the onset of neurite outgrowth and preceded the decline of DNA synthesis, suggesting that a decreased intracellular concentration of protein‐bound isoprenoid groups may contribute to the well‐documented effects of mevalonate deprivation on cell morphology and cell cycling. Fractionation of neuroblastoma cells by differential centrifugation and sucrose density‐gradient centrifugation revealed that mevalonate‐labeled proteins of 53 kDA, 22–26 kDa, and 17 kDa were concentrated in the cytosol. Proteins migrating at 45 kDa were found in both the soluble and particulate fractions, including those enriched in mitochondria and plasma membrane. The isoprenylated proteins migrating at approximately 66 kDa were localized exclusively in the nuclear fraction. When chromatin was removed from the nuclei by extraction with 2 M NaCl, the 66 kDa isoprenylated proteins remained associated with the residual components of the nuclear matrix and lamina. Isoprenylated proteins with electrophoretic mobilities similar to those observed in neuroblastoma cells were detected in a variety of established cell lines. However, there was considerable variation among cell lines in the overall efficiency of protein labeling with (14C)mevalonate and in the prominence and mobilities of specific labeled proteins in the 45–70 kDa range. Comparisons of paired transformed vs. nontransformed fibroblast cell lines suggested that the profile of mevalonate‐labeled proteins in a given cell line is not altered by malignant transformation. The finding that electrophoretically distinct isoprenylated proteins are localized in discrete subcellular compartments indicates that they do not represent dissociated subunits of a single multimeric protein complex, and provides a possible explanation for the diverse effects of mevalonate deprivation. The presence of these proteins in a wide variety of mammalian cells suggests that they play a fundamental role in cell structure and/or regulation.
Alpha tocopheryl succinate inhibits melanocyte‐stimulating hormone (MSH)‐sensitive adenylate cyclase activity in melanoma cells
Authors: Sahu Satya N. , Edwards‐Prasad Judith , Prasad Kedar N. 
Published: February 2005

AbstractD‐alpha tocopheryl succinate (vitamin E succinate), which is known to induce differentiation and growth inhibition in murine B‐16 melanoma cells, reduced basal and melanocyte‐stimulating hormone (MSH)‐stimulated adenylate cyclase (AC) activity in vitro. Vitamin E succinate treatment also reduced sodium fluoride‐ and forskoline‐stimulated AC activity of melanoma cells in vitro. Treatment of cells with vitamin E succinate (6 μg/ml) for a period of 24 hours was sufficient to reduce MSH‐stimulated AC activity. Other forms of vitamin E, such as d1‐alpha tocopheryl nicotinate, d1‐alpha tocopheryl acetate, and d1‐alpha tocopherol, which did not affect growth or morphology of melanoma cells, were relatively less effective in altering basal and MSH‐stimulated AC activity. Retinoic acid, which inhibited the growth of B‐16 melanoma cells, also reduced basal and MSH‐, NaF‐, and forskolin‐stimulated AC activity in vitro. Prostaglandin A2, which inhibited growth and altered morphology, did not change basal or MSH‐stimulated AC activity. These results show that one of the mechanisms of action of vitamin E succinate and retinoic acid on melanoma cells may involve reduction of basal and MSH‐sensitive AC activity, and this vitamin effect is not necessarily related to growth inhibition.
Fibroblast‐dependent growth of mouse mast cells in vitro: Duplication of mast cell depletion in mutant mice of w/wv genotype
Authors: Fujita Jun , Nakayama Hiroki , Onoue Hitoshi , Kanakura Yuzuru , Nakano Toru , Asai Hidekazu , Takeda Shun‐Ichi , Honjo Tasuku , Kitamura Yukihiko 
Published: February 2005

AbstractIn spite of the apparent depletion of mast cells in tissues of mutant mice of W/Wv genotype, cells with many features of mast cells do develop when bone marrow cells of W/Wv mice are cultured in the presence of pokeweed mitogen‐stimulated spleen cell‐conditioned medium (PWM‐SCM). In order to resolve this discrepancy and facilitate the analysis of the W mutation, we attempted to establish an in vitro system in which the in vivo defect of W/Wv mice can be reproduced. Cultured mast cells (CMC) were developed from bone marrow cells of either W/Wv or congenic +/+ mice, and then co‐cultured with NIH/3T3 mouse fibroblasts in media supplemented only with fetal calf serum (i.e., in the absence of PWM‐SCM). Under this condition, CMC from +/+ mice continued to divide and were maintained for more than 4 weeks. The supportive effect of NIH/3T3 cells required close‐range interactions with CMC and was not due to synthesis of the known mast cell growth factors, interleukins 3 and 4. By contrast, CMC from W/Wv mice were not maintained, and the number of mast cells remaining after 4 weeks of co‐culture was only 1% of the normal +/+ counterparts. Thus, the humoral factor‐independent and cell contact‐dependent system presented here revealed the intrinsic defects in growth and differentiation of CMC derived from W/Wv mice and might be useful for biochemical and molecular analysis of the gene product(s) encoded at the W locus.
Characterization of functional histamine H1 receptors on a cultured smooth muscle cell line
Authors: Mitsuhashi Masato , Payan Donald G. 
Published: February 2005

AbstractCultured cells of the smooth muscle line DDT1MF‐2, which was derived from a hamster vas deferens tumor, expressed histamine H1‐type receptors and responded biochemically and functionally to H1‐specific stimulation. The H1‐receptor antagonist [3H]‐pyrilamine bound specifically to 9.7 × 106 sites/DDT1MF‐2 cell with a dissociation constant (Kd) of 219 nM. The addition of histamine to suspensions of fura‐2‐loaded DDT1MF‐2 cells elicited a rapid, transient, and stimulus concentration‐dependent increase in the intracellular concentration of Ca2+ with an EC50 of 3 × 10−5 M, which demonstrated H1 receptor specificity. Moreover, in order to evaluate in vitro contractile response of individual DDT1MF‐2 cells, the degree of intracellular actin polymerization was quantified by a DNase inhibition assay. The percentage of nonpolymerized or G‐actin in DDT1MF‐2 cells was reduced in a histamine concentration‐dependent manner with an EC50 of 1 × 10−5 M and H1 receptor specificity. Histamine‐induced actin polymerization was accompanied by changes in cell shape that were consistent with cellular contraction, as assessed by flow cytometry. The H1‐type receptors of cultured DDT1MF‐2 cells thus couple histamine stimulation to a variety of functional responses of smooth muscle cells.
Recombinant interferon‐γ inhibits the mitogenic effect of platelet‐derived growth factor at a level distal to the growth factor receptor
Authors: Hosang M. 
Published: February 2005

AbstractHighly purified preparations of recombinant human interferons (rIFNs)‐αA, ‐β, and ‐γ all inhibited platelet‐derived growth factor (PDGF)‐induced DNA synthesis in normal human dermal fibroblasts, as monitored by incorporation of [3H]‐thymidine into trichloroacetic acid (TCA)‐insoluble material. rIFN‐γ was the most potent, since it blocked the PDGF response by 50% at about 10 U/ml or 0.3 ng/ml, whereas with rIFN‐αA and rIFN‐β 4000 U/ml and 600 U/ml, respectively (10 ng/ml in both cases), were required to achieve the same effect. There was a close parallelism between the ability of these rIFNs to inhibit PDGF mitogenic activity and their capacity to inhibit cell proliferation in serum‐containing medium. None of the rIFNs inhibited specific binding of 125I‐PDGF to fibroblasts, and none interfered with receptor internalization. The mechanism of action of rIFN‐γ was analyzed further. rIFN‐γ did not inhibit uptake of [3H]‐thymidine into these cells. However, it shifted if the time point of initiation of DNA synthesis from about 14 h after stimulation with PDGF to about 18 to 21 h and decreased significantly the rate of the DNA synthesis. rIFN‐γ could be added up to 6 h following stimulation with PDGF with no loss of its inhibitory effect. rIFN‐γ also blocked the mitogenic activity of epidermal growth factor and basic fibroblast growth factor. Taken together these results implicate that rIFN‐γ exerts its antimitogenic effect by inhibiting a process that occurs late in the PDGF signaling pathway and onto which the activity pathways of other mitogens converge. In view of the important role PDGF may play in wound‐healing and in the pathogenesis of the proliferative lesions of arteriosclerosis, these data point to a possible role IFN‐γ may play as a regulator of these processes in vivo.
Mitogenic action of tumor necrosis factor in human fibroblasts: Interaction with epidermal growth factor and platelet‐derived growth factor
Authors: Palombella Vito J. , Mendelsohn John , Vilček Jan 
Published: February 2005

AbstractWe have previously shown that tumor necrosis factor (TNF) can increase the number of epidermal growth factor (EGF) receptors on human FS‐4 fibroblasts and that this increase may be related to the mitogenic action of TNF in these cells. Here we show that TNF stimulated the growth of FS‐4 fibroblasts in a chemically defined, serum‐free medium in the absence of EGF. Anti‐EGF receptor antibody, which blocked the mitogenic effects of EGF in FS‐4 cells, did not inhibit the mitogenic action of TNF in serum‐free or serum‐containing medium, indicating that EGF or an EGF‐like molecule was not responsible for the mitogenic effects of TNF. However, the simultaneous addition of TNF and EGF to cells grown in serum‐free medium resulted in a synergistic stimulation of DNA synthesis and cell growth. The actions of TNF and EGF were also examined in growth‐arrested FS‐4 cells and were compared with the action of platelet‐derived growth factor (PDGF). In the absence of other growth factors, TNF was a relatively weak mitogen in growth‐arrested cells, compared with EGF or PDGF. Nevertheless, TNF synergized with EGF or high doses of PDGF in stimulating DNA synthesis. Furthermore, antibodies specific for TNF or the EGF receptor were used to selectively inhibit the actions of these two factors, after specific incubation periods, in growth‐arrested cells treated concurrently with EGF and TNF. To produce an optimal stimulation of DNA synthesis, EGF had to be present for a longer period of time than TNF. We conclude that in their synergistic action on growth‐arrested FS‐4 cells, EGF was responsible for driving the majority of the cells into S phase, while TNF appeared to make the cells more responsive to the mitogenic action of EGF. The findings indicate that TNF can cooperate with, and enhance the actions of, EGF in promoting DNA synthesis and cell division.
Osmotic forces are not critical for Ca2+‐induced secretion from permeabilized human neutrophils
Authors: Stoehr Sally Jo , Smolen James E. 
Published: February 2005

AbstractIn order to examine the role of osmotic forces in degranulation, the effects of solutes and osmolality on granule secretion were explored using both FMLP‐stimulated, intact neutrophils and Ca2+‐stimulated, permeabilized cells. We employed a HEPES‐based buffer system which was supplemented with: (a) permeant (KCl or NaCI) or impermeant (Na‐isethionate or choline‐CI) ions, or (b) permeant (urea) or impermeant (sucrose) uncharged solutes. Intact and permeabilized cells had significantly different solute requirements for degranulation. FMLP‐stimulated release from intact cells was supported by NaCI or Na‐isethionate > KCl > choline‐Cl or sucrose > urea. In contrast, the rank order of Ca2+‐stimulated release from permeabilized cells was choline‐C > Na‐isethionate, KCl, or NaCl > sucrose > urea. Hypo‐osmotic conditions caused increased levels of background granule release from both intact and permeabilized neutrophils. However, hypo‐osmolality inhibited both FMLP‐stimulated degranulation from intact cells and Ca2+‐induced release from permeabilized neutrophils. While hyperosmotic conditions inhibited stimulated release from intact cells, this inhibition was much less pronounced in permeabilized cells when the granules were directly exposed to these solutions. In fact, hyperosmotic sucrose greatly enhanced Ca2+‐induced secretion. Although isolated specific and azurophil granules showed some lytic tendencies in hypo‐osmotic buffers, the overall stability of the isolated granules did not indicate that swelling alone could effect degranulation. These results suggest that degranulation in permeabilized cells is neither due to nor driven by simple osmotic forces (under resting or stimulated conditions) and emphasize differences obtained by bathing both the granules and plasma membrane (as opposed to membranes alone) in various solutes.
Demonstration of 1α,25‐dihydroxyvitamin D3 receptor‐like molecule in ST 13 and 3T3 L1 preadipocytes and its inhibitory effects on preadipocyte differentiation
Authors: Sato Mayumi , Hiragun Akiyoshi 
Published: February 2005

AbstractThe active metabolite of vitamin D3, 1α,25‐dihydroxyvitamin D3 (1,25(OH)2D3), inhibited morphologic and enzymatic expression during differentiation of preadipocyte to adipocyte. In the presence of ∼6.4–20 × 10−10 M 1,25(OH)2D3, the triacylglycerol accumulation was only 50% of that of fully differentiated control cells. High‐affinity binding sites for 1,25(OH)2D3 binding component sediments at 3.3 S in 4–24% (w/v) sucrose gradients prepared in hypertonic buffer. Binding assay revealed that Nmax was 70 fmol/mg protein and 90 fmol/mg protein, and Kd value was 170 pM and 37 pM in cell lines ST 13 and 3T3 L1, respectively. We also found that differentiated adipocytes did not contain specific receptors for 1,25(OH)2D3. 1,25(OH)2D3, 1(OH)D3, 24,25(OH)2D3, and 24(OH)D3 all suppressed differentiation of preadipocytes to adipocytes, and the dose required closely reflected the affinities of the various metabolites and the synthetic derivative for 1,25(OH)2D3 receptor. It is suggested that the action of vitamin D3 on preadipocyte differentiation may result from a receptor‐mediated event.
Incubation of endothelial cells in a superoxide‐generating system: Impaired low‐density lipoprotein receptor‐mediated endocytosis
Authors: Poumay Y. , Ronveaux‐Dupal M.‐F. 
Published: February 2005

AbstractEndothelial cells (EC) of blood vessels are submitted to oxidative stress under various circumstances. These conditions may modify EC functions; therefore, in the present work we have studied the receptor‐mediated endocytosis of low‐density lipoproteins (LDL) and malondialdehyde‐modified LDL by the LDL receptor and the “scavenger” receptor, respectively, in cultured human umbilical vein EC after short (0‐120 minutes) incubations in a superoxide anion (O2−) generating system. In both receptor‐mediated processes, the oxidative stress produces a significant decrease at four different LDL concentrations (5‐50 μg/ml) after 120 minutes of oxidation. On the other hand, the fluid‐phase endocytosis of sucrose by EC seems to be stimulated by these conditions. Furthermore, incorporation of antioxidant enzymes in the O2−−producing system shows that H2O2 is an obligatory intermediate in order to produce the effect on the receptor‐mediated processes. Hypotheses concerning the mechanisms involved in the modifications of endocytotic processes and their implications in vivo are discussed.
Release of arachidonic acid from vascular endothelial cells: Fatty acyl specificity is observed with receptor‐mediated agonists and with the calcium ionophore A23187 but not with melittin
Authors: Rosenthal Miriam D. , Jones Janet E. 
Published: February 2005

AbstractVascular endothelial cells respond to a variety of physiological and pharmacological stimuli by releasing free arachidonic acid from membrane phospholipids, thus initiating synthesis of prostacyclin. Previous work in our laboratory has demonstrated that the thrombin‐stimulated deacylation is specific for arachidonate and structurally similar polyunsaturated fatty acids that contain a delta‐5 double bond. We now report that histamine, bradykinin, and the calcium ionophore A23187 exhibit the same fatty acid specificity as does thrombin. Experiments with both human umbilical vein and calf pulmonary artery endothelial cells indicate that these agonists stimulate the release of previously incorporated [14C]arachidonate but not 8,11,14‐[14C]eicosatrienoate or [14C]docosatetraenoate. By contrast, melittin stimulates the release of 8,11,14‐eicosatrienoate, docosatetraenoate, and oleate as well as arachidonate. These results suggest that histamine, bradykinin, and A23187 activate a common calcium‐dependent phospholipase A2. Melittin appears either to alter the substrate specificity of the receptor‐linked phospholipase A2 activity or to activate additional enzymes as well.
Specific binding, internalization, and degradation of human recombinant interleukin‐3 by cells of the acute myelogenous, leukemia line, KG‐1
Authors: Gesner Thomas G. , Allan Mufson R. , Norton Christine R. , Turner Katherine J. , Yang Yu Chung , Clark Steven C. 
Published: February 2005

AbstractWe have studied the interaction of 35S‐labeled recombinant IL‐3 with the acute myelogenous leukemia cell line, KG‐1. 35S‐IL‐3 bound to these cells in a time dependent, saturable, and specific manner at 4°C. Scatchard transformation of binding isotherms demonstrated the existence of a small number (200) of binding sites, with an apparent dissociation constant of 70‐105 pM. After a temperature shift from 4°C to 37°C, surface‐bound 35S‐IL‐3 was rapidly internalized and processed into a trichloroacetic acid soluble form that was released into the medium. Experiments to address the specificity of the IL‐3 binding site revealed that neither human IL‐2, M‐CSF, erythropoietin, transferrin, bovine insulin, nor murine nerve growth factor compete with IL‐3 for binding to KG‐1 cells. Both human and gibbon recombinant IL‐3 and, surprisingly, human recombinant GM‐CSF effectively competed the binding of the labeled IL‐3 to these cells at 4°C. The competition by GM‐CSF was found to be concentration dependent, but much higher concentrations were required to achieve the levels obtained with IL‐3. These results suggest that GM‐CSF may also interact with the high‐affinity IL‐3 binding site on KG‐1 cells or, alternatively, that GM‐CSF binding to its own receptor may decrease the affinity of the IL‐3 receptor for its ligand.