bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential expression of cell surface glycoproteins on various organ‐derived microvascular endothelia and endothelial cell cultures
Authors: Belloni Paula N. , Nicolson Garth L. 
Published: February 2005

AbstractGlycoproteins expressed on the luminal surfaces of microvascular endothelium derived from various murine organs were analyzed and compared with those expressed by cultured vascular endothelial cells. Cell‐surface vascular proteins were radiolabeled in situ via intracardiac perfusion with lactoperoxidase/Na125l. Autoradiography confirmed that the radiolabel was restricted to the vessel lumen in most tissues. Controls contained 125l‐labeled serum proteins to identify adsorbed serum components. Glycoproteins were analyzed by western enzymelinked lectin analysis using detergent extracts of 125l‐labeled microvessels isolated from different organs. The western transfers were probed with a panel of lectin‐peroxidase conjugates to determine differences in protein glycosylation. The same transfers were also screened for exposed 125l‐labeled cell‐surface proteins by autoradiography. This dual analysis detected glycoprotein patterns unique for each organ. At least seven major proteins (Mr ∼ 180 K, 130 K, 95 K, 80 K, 75 K, 60 K, 12 K) were common to microvessels derived from each organ; however, certain glycoproteins appeared to be expressed differentially in particular organs. For example, a Mr ∼ 135 K WGA‐binding glycoprotein was detected in brain microvessels, whereas another WGA‐binding glycoprotein of Mr ∼ 40 K was detected only in kidney. In lung microvessels, a Mr ∼ 140 K WGA binding glycoprotein and a Mr ∼ 55 K RCA‐l‐binding galactoprotein were expressed preferentially, and liver microvessels displayed Mr ∼ 220 K protein and a Mr ∼ 135 K PNA‐binding galactoprotein. The cell‐surface‐iodinated protein profiles from in situ labeled microvessels were similar to profiles derived from cultured bovine aortic endothelial cells and several short‐term endothelial cell cultures isolated from different organs. The results from this study suggest that organ‐associated endothelia express glycoprotein fingerprints unique to each organ.
Influence of the deprivation of a single amino acid on cellular proliferation and survival in rat 3Y1 fibroblasts and their derivatives transformed by a wide variety of agents
Authors: Tanaka Hiroaki , Zaitsu Hirokazu , Onodera Kazukiyo , Kimura Genki 
Published: February 2005

AbstractWe compared proliferation and survival of various syngeneic transformed cell lines under conditions of depletion of 15 amino acids in Dulbecco‐Eagle's medium. We used a normal fibroblast line 3Y1 and 22 transformed sublines of 3Y1 which had been induced by one of seven transforming agents‐simian virus 40, mouse polyomavirus, adenovirus type 12, E1A gene of adenovirus type 12, cDNA of Harvey murine sarcoma virus, Rous sarcoma virus, or N‐methyl‐N′‐nitro‐N‐nitrosoguanidine. Unlike other untransformed cells examined (mouse BALB/c‐3T3 line, mouse NlH‐3T3 line, and primary Fischer rat embryo fibroblasts), 3Y1 ceased to proliferate and accumulated in a viable state with a G1‐phase DNA content under 14 singular deprivations of amino acid. None of the transformed 3Y1 lines completely arrested in the G1 phase of the cell cycle and each showed different levels of survival, depending on each transforming agent. As for transformed 3Y1 cells induced by a given virus or a given transforming gene, any one of the three sublines shared the same trend with respect to proliferation and survival. Transformed derivatives induced by N‐methyl‐N′‐nitro‐N‐nitrosoguanidine showed almost the same trend in proliferation, but the patterns of survival were not uniform. Our observations suggest that the unique responses of 3Y1 to amino acid depletion are differently modified by different transforming agents.
Normal nonmetastatic human trophoblast cells share in vitro invasive properties of malignant cells
Authors: Yagel Simcha , Parhar Ranjit S. , Jeffrey John J. , Lala Peeyush K. 
Published: February 2005

AbstractFirst‐trimester normal human trophoblast cells show some phenotypic similarities to malignant cells, e.g., rapid proliferation and ability to invade neighboring tissue, including basement membrane in situ, but do not have the ability for unlimited growth or metastasis. The present study examined whether the invasive ability of normal trophoblast cells is an intrinsic property of these cells, independent of the microenvironment provided by the pregnant uterus, and if so, whether they share some of the molecular mechanisms of invasion exercized by metastatic malignant cells. The ability of in vitro grown human trophoblast lines to invade an epithelium‐free human amniotic membrane was measured from the temporal kinetics of retention of radioactivity within this membrane resulting from a penetration by 125I‐iododeoxyuridine‐labeled trophoblast cells. The magnitude of this invasion was compared to that of the highly metastatic human JAR‐choriocarcinoma cell line and murine B16F10 melanoma line. Trophoblasts were found to share some of the same molecular mechanisms of invasion with the metastatic cell lines. Inhibitors of collagenase, plasmin, plasminogen, and plasminogen activators completely prevented invasion of the amnion by the trophoblast lines as well as by the metastatic JAR and B16F10 lines. Mersalyl, a compound known to activate collagenase, stimulated invasion by all cell lines tested, including under conditions in which plasmin activity was inhibited. In addition, trophoblasts produced significant levels of type IV collagenase and laminin, both of which appear to be important products of metastatic tumor cells required for basement membrane invasion. It may be concluded from these findings that the invasive property of first trimester human trophoblasts is genetically determined; that the magnitude of amnion invasion cannot differentiate between metastatic cell lines and invasive but nonmetastatic cell lines; and that invasiveness is not a sufficient prerequisite for metastatic ability.
Cultured primate aortic smooth muscle cells express both the PDGF‐‐A and PDGF‐B genes but do not secrete mitogenic activity or dimeric platelet‐derived growth factor protein
Authors: Valente Anthony J. , Delgado Ruby , Metter John D. , Cho Chong , Sprague Eugene A. , Schwartz Colin J. , Graves Dana T. 
Published: February 2005

AbstractProliferation of smooth muscle cells (SMC) in the arterial intima of man and experimental animals is important in the pathogenesis of atherosclerosis. Vascular SMC proliferation in vitro is stimulated by a number of agents, including the potent protein mitogen, platelet‐derived growth factor (PDGF). Recent studies on rat arterial SMC indicate that these cells may, under certain circumstances, synthesize PDGF protein mitogens, suggesting that the regulation of SMC proliferation in vivo may have an autocrine or paracrine component. In this study we demonstrate that cultured nonhuman primate (baboon) aortic SMC transcribe both the PDGF‐A and PDGF‐B genes but do not secrete detectable mitogenic activity characteristic of native PDGF. The absence of this activity was not due to the presence in the cell conditioned medium of factors inhibitory for PDGF‐mediated mitogenic activity. Metabolic labeling of the cells and immunoprecipitation with specific antibodies to human PDGF did not detect a dimeric (30 kDa) PDGF protein in either the intracellular or extracellular compartments, but instead identified PDGF‐related proteins of molecular weight 12 kDa and 100 kDa. These data suggest the presence in vascular SMC of a mechanism regulating the translation of PDGF mRNA that may play an important role in the control of SMC proliferation in vivo.
Differential response of normal human fibroblasts to bombesin versus thrombin
Authors: Hendey Bill , Mamrack Mark D. 
Published: February 2005

AbstractNormal human diploid fibroblasts (WS‐1 cells) were growth‐arrested under serum‐free conditions for 48 hr. The addition of fetal bovine serum (10% final concentration) to these cells stimulated [3H]‐thymidine incorporation into DNA and phosphoinositide breakdown over nine‐fold. Thrombin, at concentrations above 0.1 unit/ml (u/ml), was also effective at stimulating DNA synthesis and phosphoinositide breakdown as well as causing a rise in intracellular pH. In contrast, the peptide bombesin (concentrations ranging from 1 nM to 100 nM) stimulated phosphoinositide breakdown but did not enhance DNA synthesis or cause an increase in cytoplasmic pH. The time course of accumulation of inositol phosphates differed in response to these agents. The thrombin effect peaked rapidly and leveled off after 5 min while the bombesin effect showed a constant increase for 30 min. Serum showed an intermediate response. The different rates of inositol phosphate accumulation observed with the two growth factors is viewed as representing a difference in the mechanism of phosphoinositide turnover. The relationship between the difference in phosphoinositide turnover and the initiation of DNA synthesis is also discussed.
Expression of melanocyte stimulating hormone receptors correlates with mammalian pigmentation, and can be modulated by interferons
Authors: Kameyama Koichiro , Montague Paul M. , Hearing Vincent J. 
Published: February 2005

AbstractThe relationship between melanogenesis and the expression of melanocyte stimulating hormone (MSH) receptors on the surface of melanocytes was examined using sublines generated from the melanotic JB/MS melanoma. JB/MS cells were propagated in long term culture to allow for phenotypic drift in their characteristics of differentiation, and then were cloned; the cloned cells ranged from well differentiated and pigmented to undifferentiated and amelanotic. Spontaneous and MSH‐induced melanogenesis in these different lines was measured and correlated with the number of MSH receptors expressed. After 6 months of in vitro culture, the ability of the cells to respond to MSH was significantly reduced, as were the number of MSH receptors expressed; the cells had reduced pigmentation and were relatively undifferentiated histologically. Subsequently, clonally‐derived pigmented cells were found to have numbers of surface MSH receptors (approximately 60,000 per cell) and levels of melanogenic activity similar to the original JB/MS cell line.However, an amelanotic clone had an even more dramatically reduced level of pigmentation which correlated with a further decrease in the expression of MSH receptors (< 1,000 per cell) and the production of a potent melanogenic inhibitor. We also examined the responses of these various sublines to α, β, and γ‐interferons and found significant heterogeneity in their abilities to respond to these cytokines. This study clearly shows that there is a direct correlation between melanogenesis and the expression of MSH receptors on the surface of melanocytes, and that melanogenic inhibitors may be critically involved in the regulation of mammalian pigmentation.
Growth factor production by a human megakaryocytic tumor cell line
Authors: Witte David P. , Stambrook Peter J. , Feliciano Estrella , Jones Cindy L. A. , Lieberman Michael A. 
Published: February 2005

AbstractA recently described human megakaryocytic tumor cell line was analyzed for the presence of growth factor activity and was found to produce large quantities of transforming growth factor b̃‐like (TGF‐b̃) and basic fibroblast growth factor‐like (bFGF) activities. Growth factor activities were identified using a radioreceptor assay for the TGF‐b̃‐like activity, a heparin‐binding assay for the b‐FGF‐like activity, and a demonstration of distinct biological activities for each type of factor. Tumor poly‐A+ RNA revealed strong signals when probed with complementary DNA corresponding to bovine basic FGF and human growth factor (EGF) and TGF‐α. The levels of EGF and TGF‐α produced in the tumor line were too low to be detected by radioreceptor assays. Relative levels of messenger RNA encoding each of the growth factors reflected the relative levels of each of the respective factors tested. These data represent the first definitive identification of FGF‐like activities in megakaryocytic‐like cell lines. Interestingly, the line displayed little activity similar to platelet‐derived growth factor (PDGF) when assayed either biochemically or by poly A+ RNA analysis.
Comparative study of the tyrosine phosphorylation of proteins in Swiss 3T3 fibroblasts stimulated by a variety of mitogenic agents
Authors: Pasquale Elena B. , Maher Pamela A. , Singer S. J. 
Published: February 2005

AbstractWe have carried out a comparative study of the protein tyrosine phosphorylation induced by a wide range of mitogenic stimuli on a single cell type, Swiss 3T3 mouse fibroblasts. For this purpose we have used high‐affinity antibodies directed to phosphotyrosine residues on proteins (Wang: Mol. Cell. Biol. 5:3640–3643, 1985) in immunoblotting and immunofluorescence microscopy experiments. Immunoblotting experiments showed that all of the mitogens tested, including epidermal growth factor, platelet‐derived growth factor, basic fibroblast growth factor, insulin, fetal calf serum, trypsin, and 12‐O‐tetradecanoylphorbol‐13‐acetate, increased the phosphorylation on tyrosine of a number of proteins. Most of the increase in tyrosine phosphorylation induced by each factor involved a small set of proteins with apparent molecular weights (Mr) above 50,000. Following stimulation with epidermal growth factor, platelet‐derived growth factor, and basic fibroblast growth factor, increased phosphotyrosine modification of proteins with molecular weights corresponding to those of the respective receptors was observed. A protein band of apparent Mr 160,000 contained substantially increased levels of phosphotyrosine following insulin treatment, but tyrosine phosphorylation of the insulin receptor was apparently below the level of detectability. The phosphotyrosine content of proteins with apparent Mr of 220,000, 120,000, and 70,000 was increased by all the agents tested. Phosphorylation on tyrosine of most of the proteins increased within a few minutes of the mitogenic stimulation, reached a peak, and returned more slowly to basal levels. Immunofluorescence labeling with the antibodies specific for phosphotyrosine showed a substantial increase in the amount of phosphotyrosine containing proteins only in the presence of platelet‐derived growth factor and fetal calf serum. This finding suggests that most of the proteins phosphorylated on tyrosine in Swiss 3T3 fibroblasts are not concentrated in specific subcellular structures, but rather are diffusely distributed throughout the cell and are therefore not detectable by immunofluorescence microscopy.
Enhanced constitutive expression of the 27‐kDa heat shock proteins in heat‐resistant variants from chinese hamster cells
Authors: Chrétien Pierre , Landry Jacques 
Published: February 2005

AbstractFour heat‐resistant variants were isolated after treatment of Chinese hamster lung cells with the mutagen ethyl methane sulfonate, followed by a single‐step selection procedure consisting in a severe hyperthermic treatment of 4 h at 44°C. The isolated clones had a stable resistant phenotype for at least 150 generations during which they showed a 5,000‐fold increased survival to a 4‐h treatment at 44°C when compared to wild‐type cells. Comparative two‐dimensional electrophoretic analyses of proteins revealed that, like induced thermotolerant wild‐type cells (i.e., cells induced to a transient physiological state of thermotolerance by a sublethal heat conditioning treatment administered 18 h before), the heat‐resistant variants had, at normal temperature, an increased content of a heat‐shock protein with Mr of 27,000 (HSP27). In three of the four heat‐resistant variants, the increased content of HSP27 was correlated with a two‐fold increase in the constitutive level of the mRNA encoding HSP27. Chinese hamster HSP27 is composed of three species that differ in their relative isoelectric point, among which the two most acidic forms are phosphoproteins. In both the heat‐resistant variant and wild‐type cells, heat shock induces a rapid enhancement of the phosphorylation of HSP27: maximal phosphorylation occurs within 10 min upon changing the incubation temperature from 35° to 44°C. A concomitant shift in silver‐staining intensity is rapidly detectable between the three isoforms, which seems to indicate that the two phosphorylated species represent post‐translational modifications of the more basic species. It is concluded that most likely the enhanced expression of HSP27 is linked to the resistant phenotype of the variants. The study provides supporting evidence that both the content and phosphorylation status of HSP27 are determining factors in the ability of cells to survive hyperthermic treatments.
Bombesin enhancement of cAMP accumulation in swiss 3T3 cells: Evidence of a dual mechanism of action
Authors: Millar Jonathan B. A. , Rozengurt Enrique 
Published: February 2005

AbstractAddition of bombesin in the presence of either forskolin or cholera toxin caused a marked (4–6 fold) enhancement of cAMP accumulation in Swiss 3T3 cells. This effect was time and concentration dependent, induced by various bombesin‐like peptides and blocked by a bombesin antagonist. Enhancement of cAMP accumulation by bombesin was diminished by chronic pretreatment with phorbol dibutyrate implicating the involvement of protein kinase C in the activation. Pretreatment with pertussis toxin, which uncouples protein kinase C activation from cAMP accumulation (Proc. Natl. Acad. Sci. U.S.A., 84:2282, 1987) also inhibited bombesin enhancement of cAMP. Bombesin was also shown to release E type prostaglandins into the medium, an effect which was abolished by the cyclooxgenase inhibitor indomethacin. Low concentrations (100 nM) of indomethacin partially inhibited the accumulation of cAMP by bombesin in the presence of forskolin indicating that the release of E type prostaglandins into the medium is also involved in the accumulation of cAMP by bombesin. The additive nature of PBt2‐mediated down‐regulation and treatment with indomethacin suggests that activation of protein kinase C and the release of E type prostaglandins provide two distinct pathways involved in the enhancement of cAMP accumulation by bombesin. Finally, bombesin in the presence of forskolin stimulated the phosphorylation of the intermediate filament component vimentin, identified in the accompanying paper as a substrate for a cAMP dependent protein kinase in intact Swiss 3T3 cells.
Regulatory volume decrease in alveolar macrophages: Cation loss is not correlated with changes in membrane recycling
Authors: Novak Jeanne M. , Cala Peter M. , Ward Diane McVey , Buys Saundra S. , Kaplan Jerry 
Published: February 2005

AbstractAlveolar macrophages regain their normal volume after swelling in hypo‐osmotic solutions. This process, termed regulatory volume decrease (RVD), is initiated 3–5 minutes after exposure of cells to hypo‐osmotic solutions, and by 30 min, near‐normal volumes are attained. Volume decrease does not occur at 0°C or in solutions in which Na+ has been replaced by K+, or Cl− by the impermeant anion gluconate. These results, as well as direct measurement of intracellular cations, indicate that decrease in cell volume result primarily from the loss of K+ and Cl− and are similar to RVD in lymphocytes. Kinetic analysis of cation loss, both by directly measuring changes in intracellular cation content and by assaying rubidium efflux, showed that cation loss occurred immediately upon media dilution. The rate of cation loss fit first‐order kinetics and preceded both the initiation of volume decrease and the maximum increase in surface receptor number. These results suggest that the cation transporters responsible for RVD are located at the cell surface and that regulation of activity is not dependent on alterations in membrane movement.
Differentiation of HL‐60 cells is associated with an increase in the 35‐kDa protein lipocortin I
Authors: William Felicia , Mroczkowski Barbara , Cohen Stanley , Kraft Andrew S. 
Published: February 2005

AbstractLipocortin I, a 35‐kDa protein, has been detected in terminally differentiated monocytes and neutrophils. This calcium‐phospholipid binding protein appears to be identical to a 35‐kDa protein that can serve as a substrate for the EGF‐receptor/tryosine kinase. We have used the human myelocytic cell line HL‐60 to explore whether differentiation of hematopoietic cells is associated with changes in the level of lipocortin I. We find that differentiation of HL‐60 cells toward the macrophage lineage by the addition of phorbol esters or vitamin D3 or toward neutrophils with dibutyryl cyclic AMP or dimethyl sulfoxide is accompanied by an increase in the cellular content of lipocortin I. In comparison, treatment of HL‐60 cells with bryostatin 1, a compound that activates protein kinase C but does not differentiate HL‐60 cells, did not effect the level of 35 kDa protein. We have developed a radioimmunoassay to quantitate this protein by using a polyclonal antibody to a synthetic amino terminal peptide of the 35‐kDa protein. This antibody recognizes purified pig lung 35‐kDa protein as well as a single 35‐kDa protein in HL‐60 and A‐431 cells as determined by Western blotting and immune precipitation. Differentiated HL‐60 cells contain 2.6‐fold the amount of 35‐kDa protein found in undifferentiated HL‐60 cells. Our findings that the addition of phorbol esters to HL‐60 cells results in an increase in the mRNA for the 35‐kDa protein and in an increase in the incorporation of 35S‐methionine into the protein suggest that transcriptional activation or increased stability of the mRNA is responsible for the increased rate of synthesis and accumulation of lipocortin I during differentiation of these cells. In the absence of added divalent cations, we have determined that in differentiated HL‐60 cells 79% of lipocortin I protein is located in the cytosol while 21% of the total cellular protein is bound to the particulate fraction. The 35‐kDa protein can be removed from the particulate fraction by incubation with chelators or treatment with phospholipase A2 or phospholipase C. Addition of the calcium ionophore A23187 to intact differentiated HL‐60 cells causes the 35‐kDa protein to associate with the particulate fraction of the cell, suggesting that modulation of intracellular calcium levels may play a role in changing the intracellular location of this protein.
Sulfogalactolipid binding protein SLIP 1: A conserved function for a conserved protein
Authors: Law H. , Itkonnen O. , Lingwood C. A. 
Published: February 2005

AbstractWe have studied the species and tissue expression of the 68kD sulfogalactolipid binding protein SLIP 1, originally detected in the male germ cells of the rat (Lingwood: Can. J. Biochem. Cell Biol., 63:1077–1085, 1985). OUr results show that SLIP 1 has been highly conserved during evolution and is found in the testes of all vertebrates tested. In studies in the rat, we have found that SLIP 1 is, however, tissue restricted, being found only in the brain (also a major site of sulfogalactolipid biosynthesis) in addition to the testis. SLIP 1 was also detected in mammalian oocytes. The SLIP 1 species detected in brain and oocytes retain the sulfogalactolipid‐binding characteristics of rat testicular SLIP 1, indicating that, in addition to immunological features, the glycolipid‐binding function of SLIP 1 is conserved in these tissues.