bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protection of transforming growth factor β activity by heparin and fucoidan
Authors: McCaffrey Timothy A. , Falcone Domenick J. , Vicente Diane , Du Baoheng , Consigli Seth , Borth Wolfgang 
Published: February 2005

AbstractThe transforming growth factor‐β (TGF‐β) family of proteins exert diverse and potent effects on proliferation, differentiation, and extracellular matrix synthesis. However, relatively little is known about the stability or processing of endogenous TGF‐β activity in vitro or in vivo. Our previous work indicated that (1) TGF‐β1 has strong heparin‐binding properties that were not previously recognized because of neutralization by iodination, and (2) heparin, and certain other polyanions, could block the binding of TGF‐β1 to α2‐macroglobulin (α2‐M). The present studies investigated the influence of heparin‐like molecules on the stability of the TGF‐β1 signal in the pericellular environment. The results indicate that heparin and fucoidan, a naturally occurring sulfated L‐fucose polymer, suppress the formation of an initial non‐covalent interaction between 125I‐TGF‐β1 and activated α2‐M. Electrophoresis of 125I‐TGF‐β1 showed that fucoidan protects TGF‐β1 from proteolytic degradation by plasmin and trypsin. While plasmin caused little, if any, activation of latent TGF‐β derived from vascular smooth muscle cells (SMC), plasmin degraded acid‐activated TGF‐β, and purified TGF‐β1, and this degradation was inhibited by fucoidan. In vitro, heparin and fucoidan tripled the half‐life of 125I‐TGF‐β1 and doubled the amount of cell‐associated 125I‐TGF‐β1. Consistent with this protective effect, heparin‐ and fucoidan‐treated SMC demonstrated elevated levels of active, but not latent, TGF‐β activity. © 1994 wiley‐Liss, Inc.
Modifications in the synthesis of membrane‐associated chondroitin sulfate proteoglycans in hemopoietic progenitor cells are accompanied by alterations in their adhesive properties
Authors: Conget Paulette , Minguell José J. 
Published: February 2005

AbstractIn vitro studies in our laboratory have indicated that murine hemopoietic progenitor cell (HPC) lines, irrespective of their differentiation stage, synthesize and accumulate in the cell membrane a unique species of chondroitin sulfate proteoglycan (CS‐PG). It has been postulated that CS‐PG participates in HPC adhesion to pericellular stromal fibronectin by interacting with its heparin‐promoting binding region. To further support this contention, we first attempted to modify CS‐PG synthesis in HPC by the use of chlorate and p‐nitrophenyl (β‐D‐xyloside), which inhibit sulfation and glycosaminoglycan (GAG) addition in proteoglycans, respectively. We then studied the effect that these modifications may have in the adhesive capacity of HPC to interact with fibronectin and its cell‐ and heparin‐promoting binding chymotryptic fragments. Treatment with chlorate which resulted in a decreased sulfation of membrane‐associated 35 S‐labeled CS‐PG, as judged by ion exchange chromatography, did not affect HPC adhesion to fibronectin or its fragments. However, β‐xyloside treatment which reduces the abundance of membrane‐associated CS‐PG, as evidenced by molecular sieve chromatography, produced a major and specific decrease in HPC adhesion to the heparin‐promoting binding fragment of fibronectin. These results indicate that CS‐PG are involved in HPC interaction with fibronectin, in a mode that seems to be dependent on the differentiation stage of HPC. © 1994 wiley‐Liss, Inc.
Cisplatin sensitivity correlates with its ability to cause cell cycle arrest via a wee1 kinase‐dependent pathway in schizosaccharomyces pombe
Authors: Thiebaut Franz , Enns Robert , Howell Stephen B. 
Published: February 2005

AbstractMutants of Schizosaccharomyces pombe were used to define genes involved in the cell cycle arrest produced by cisplatin (DDP), an agent that causes both DNA damage and inhibition of DNA synthesis. Previous work has demonstrated that strains with defective or absent wee 1+ function fail to arrest in G2 when DNA is damaged, but do arrest when DNA synthesis is inhibited (Rowley et al., 1992a, Nature, 356:353–355). Strains defective in wee 1+ function, or in the ability of the wee 1+ kinase to regulate cdc2, failed to arrest following DDP exposure, as did a rad1‐1 mutant. All strains failing to arrest in G2 were hypersensitive to DDP. Thus, DNA damage rather than inhibition of DNA synthesis is causative of DDP‐induced cell cycle arrest. In addition, this work shows that the wee 1+ and rad 1+ gene products are required for successful DDP‐induced arrest, and suggests that the ability of S. pombe to arrest is a major determinant of sensitivity to DDP. © 1994 wiley‐Liss, Inc.
Cell cycle controlled histone H1, H3, and H4 genes share unusual arrangements of recognition motifs for HiNF‐D supporting a coordinate promoter binding mechanism
Authors: van den Ent Fusinita M. I. , Van Wijnen André J. , Lian Jane B. , Stein Janet L. , Stein Gary S. 
Published: February 2005

AbstractCell cycle and growth control of the DNA binding and transactivation functions of regulatory factors provides a direct mechanism by which cells may coordinate transcription of a multitude of genes in proliferating cells. The promoters of human DNA replication dependent histone H4, H3, and H1 genes interact with at least seven distinct proteins. One of these proteins is a proliferation‐specific nuclear factor, HiNF‐D, that interacts with a key cis‐regulatory element (H4‐Site II; 41 bp) present in H4 genes. Here we describe binding sites for HiNF‐D in the promoters of H3 and H1 genes using cross‐competition, deletion analysis, and methylation interference assays, and we show that HiNF‐D recognizes intricate arrangements of at least two sequence elements (CA‐ and AG‐motifs). These recognition motifs are irregularly dispersed and distantly positioned in the proximal promoters (200 bp) of both the H3 and H1 genes. In all cases, these motifs either overlap or are in close proximity to other established transcriptional elements, including ATF and CCAAT sequences. Although HiNF‐D can interact with low affinity to a core recognition domain, auxiliary elements in both the distal and proximal portions of each promoter cooperatively enhance HiNF‐D binding. Thus, HiNF‐D appears to bridge remote regulatory regions, which may juxtapose additional trans‐activating proteins interacting within histone gene promoters. Consistent with observations in many cell culture systems, the interactions of HiNF‐D with the H4, H3, and H1 promoters are modulated in parallel during the cessation of proliferation in both osteosarcoma cells and normal diploid osteoblasts, and these events occur in conjunction with concerted changes in histone gene expression. Thus, HiNF‐D represents a candidate participant in coordinating transcriptional control of several histone gene classes. © 1994 wiley‐Liss, Inc.
Characterization of regulatory volume decrease in the THP‐1 and HL‐60 human myelocytic cell linesn
Authors: Gallin Elaine K. , Mason Toni M. , Moran Arie 
Published: February 2005

AbstractExposure to hypotonic stress produces a transient increase in cell volume followed by a regulatory volume decrease (RVD) in both THP‐1 and HL‐60 cells. In contrast, cells exposed to hypotonic stress in a high K/low Na Hanks' solution not only failed to volume regulate, but displayed a secondary swelling. Thus, while an outward K gradient was required ful KVD, the secondary swelling indicated that hypotonic stress increased permeability in the absence of a negative membrane potential. The K channel blocker quinine (1–4 mM) blocked RVD in both cell types. Gramicidin's ability to overcome the quinine block of RVD indicated that RVD is mediated by a quinine‐sensitive cation transport mechanism that is independent of the swelling‐induced anion transport mechanism. Barium (1–4 mM), another K channel blocker, slowed the rate of RVD, while 4‐aminopyridine, charybdotoxin, tetraethylammonium chloride, tetrabutylammonium chloride, and gadolinium had no effect on RVD. Furthermore, RVD was not mediated by calcium‐activated conductances, since it occurred normally in Ca‐free medium, in medium containing cadmium, and in BAPTA‐loaded cells. Gramicidin produced little or no volume change in isotonic medium, suggesting that basal C1 permeability of both THP‐1 and HL‐60 cells is low. However, swelling induced an anion efflux pathway that is permeable to both chloride and bromide, but is impermeable to methanesulfonate and glutamate. The anion channel blocker 3,5‐diiodosalicylic acid (DISA) antagonized RVD in both cell types. In conclusion, RVD in THP‐1 and HL‐60 cells is mediated by independent anion and cation transport mechanisms that involve both a DISA‐sensitive anion pathway and a quinine‐inhibitable K efflux pathway, neither of which requires increases in intra‐cellular calcium to be activated. © 1994 wiley‐Liss, Inc.
Characterization of rat aortic smooth muscle cells resistant to the antiproliferative activity of heparin following long‐term heparin treatment
Authors: Bârzu Tereza , Pascal Marc , Herbert Jean‐Marc , Carayon Pierre , Desmoulière Alexis 
Published: February 2005

AbstractVascular smooth muscle cells (SMC) do not represent a homogeneous population (Schwartz et al., 1990, Am. J. Pathol. 136:1417–1428). Cellular clones resistant to the antiproliferative activity of heparin were isolated from rat aortic SMC cultures (Pukac et al., 1990, Cell Regul., 1:435–443; San Antonio et al., 1993, Arterioscler. Thromb., 13:748–757) and from explant of human arterial restenotic lesions (Chan et al., 1993, Lancet, 341:341–342). We have shown in the present study that long‐term treatment (growth medium supplemented with 200 μg/ml heparin, from the second to the tenth passage) of rat aortic SMC, without cell cloning, resulted in a significant loss of sensitivity to the growth inhibition by heparin and its derivatives. The heparin resistance was stable after growing cells for two passages in heparin‐free medium, suggesting the selection of a particular phenotype. We tried to characterize these cells and to determine the causes of the resistance to the growth inhibition by heparin. Heparin‐treated SMC (HT‐SMC) were smaller than their control culture at the same passage, expressed less α‐SM actin, and did not overgrow after reaching confluence. As in the heparin‐resistant clones (San Antonio et al., 1993, Cell Regul., 1:435–443) expression of α‐SM actin could be increased in HT‐SMC by heparin addition before Western blotting. Heparin resistance was associated with a tenfold decrease in [3H]‐heparin binding capacity (Bmax=1.9 × 106 sites per cell) compared to control cultures (Bmax = 1.7 × 107 sites per cell), which was irreversible after growing the cells for two additional passages in heparin‐free medium. We also investigated protein kinase C (PKC) in HT‐SMC in terms of both enzymatic activity and protein expression (evaluated by [3H]‐staurosporine and [3H]‐phorbol‐12,13‐dibutyrate binding). We found that HT‐SMC had only half the PKC activity and expression as control SMC. Therefore, long‐term treatment of rat aortic SMC with heparin allowed the selection of a less differentiated subpopulation of cells, exhibiting low sensitivity to the growth inhibition by heparin, which could be related to the low capacity of binding heparin and to a lower PKC activity and/or expression. © 1994 Wiley‐Liss, Inc.
Differential effects of warfarin on mRNA levels of developmentally regulated vitamin K dependent proteins, osteocalcin, and matrix Gla protein in vitro
Authors: Barone Leesa M. , Aronow Michael A. , Tassinari Melissa S. , Conlon Donna , Stein Gary S. , Lian Jane B. , Canalis Ernesto 
Published: February 2005

AbstractThe role of the vitamin K dependent proteins, osteocalcin which is bone specific and matrix Gla protein (MGP) found in many tissues, has been studied by inhibition of synthesis of their characteristic amino acid, γ‐carboxyglutamic acid (Gla) with the anticoagulant sodium warfarin. The effect of sodium warfarin on expression of these proteins, and other phenotypic markers of bone and cartilage during cellular differentiation and development of tissue extracellular matrix, was examined in several model systems. Parameters assayed include cell growth (reflected by histone gene expression) and collagen types I and II, osteopontin, alkaline phosphatase, and mineralization. Studies were carried out in calvarial bone organ cultures, normal diploid rat osteoblast and chondrocyte cultures, and rat osteosarcoma cell lines ROS 17/2.8 and 25/1. In normal diploid cells, warfarin consistently stimulated cell proliferation (twofold). In osteoblast cultures, MGP mRNA levels were generally increased (three to tenfold). Notably, MGP mRNA levels were not affected in chondrocyte cultures, either with chronic or acute warfarin treatments. Osteocalcin mRNA levels and synthesis were decreased up to 50% in ROS 17/2.8 cells and in chronically treated (1 and 5 μg/ml sodium warfarin) rat osteoblast cultures after 22 days. Early stages of osteoblast phenotype development from the proliferation period to initial tissue formation (nodules) appeared unaffected; while after day 14, further growth and mineralization of the nodule areas were significantly decreased in warfarin‐treated cultures. In summary, warfarin has opposing effects on the expression of two vitamin K dependent proteins, MGP and osteocalcin, in osteoblast cultures and MGP is regulated differently between cartilage and bone as reflected by cellular mRNA levels. Additionally, warfarin effects expression of nonvitamin K dependent proteins which may reflect the influence of warfarin on endoplasmic reticulum associated enzymes. © 1994 Wiley‐Liss, Inc.
Regulation of insulin‐like growth factor 1 binding protein 3 levels by epidermal growth factor and retinoic acid in cervical epithelial cells
Authors: Andreatta‐Van Leyen Sheila , Hembree Joan R. , Eckert Richard L. 
Published: February 2005

AbstractInsulin‐like growth factors (IGFs) are important regulators of epithelial cell growth. The mitogenic activity of these factors is influenced by the levels of extracellular IGF binding proteins, including insulin‐like growth factor binding protein 3 (IGFBP‐3). In the present report we study the effects of epidermal growth factor (EGF) and all‐trans‐retinoic acid (RA) on IGFBP‐3 RNA and protein levels in human papillomavirus‐immortalized cervical epithelial cells. Treatment of ECE16‐1 cells with 3–20 ng/ml EGF causes a marked reduction in IGFBP‐3 levels. In contrast, 1 μM RA increases IGFBP‐3 mRNA and protein levels in the presence or absence of 20 ng/ml EGF. The response is concentration dependent with a half‐maximal increase observed at 1 nM RA. RA is able to reverse the EGF suppression when added simultaneously or 3 days after initiation of EGF treatment. Conversely, when cells are treated with RA, IGFBP‐3 levels increase within 24 h and subsequent addition of EGF is without effect. Thus, the RA‐dependent increase in IGFBP‐3 levels is dominant over the EGF suppression. The increased IGFBP‐3 levels are correlated with RA suppression of proliferation. Similar RA effects on IGFBP‐3 mRNA levels were observed in other cervical epithelial cell lines (i.e., ECE16‐D1, ECE16‐D2, and CaSki). These results suggest that RA may act to inhibit cervical cell growth by increasing IGFBP‐3 levels and reducing the extracellular concentration of free insulin‐like growth factor I (IGFI) and/or, alternatively, IGFBP‐3 may inhibit cell growth by direct effects on the cell, independent of IGFI. © 1994 Wiley‐Liss, Inc.
Role of laminin in the Morphogenetic cascade during Coculture of sertoli cells with peritubular cells
Authors: Tung Pierre S. , Fritz Irving B. 
Published: February 2005

AbstractObservations summarized in this article demonstrate an essential role of laminin during the restructuring processes that occur during coculture of Sertoli cells with testicular peritubular cells. The data presented indicate that laminin becomes detectable on the free surfaces of Sertoli cells only after reaggregation of Sertoli cells begins, coincident with the initiation of repolarization at a specific stage of the morphogenetic cascade. We infer that laminin deposited at this time serves as a cohesion molecule that permits peritubular cells to come into close contact with Sertoli cells and subsequently to spread along the free surfaces of Sertoli cells. These conclusions and inferences are based on the following experiments. Cycloheximide‐treated peritubular cells in culture in MEM containing cycloheximide readily attach to laminin‐coated polystyrene surfaces. By contrast, added peritubular cells do not attach onto monolayers of Sertoli cells in monoculture or onto Sertoli cells plated on top of peritubular cells and maintained in coculture for periods of up to 48 h in cocultures maintained for 6 days, however, labeled peritbular cells readily adhere to the free surfaces of reaggregated Sertoli cells. Laminin, but not fibronectin, appears on the free surfaces of the reaggregated Sertoli cells atthis time, coinciding with the period of initial mound formation. The addition of antilaminin IgG, but not antifibronectin IgG, blocks the attachment of cycloheximide‐treated peritubular cells to laminin‐coated plates and also blocks the subsequent migration of peritubular cells required to form a monolayer. Similarly, anti‐laminin IgG inhibits the attachment and spreading of labeled peritubular cells seeded on the free surfaces of reaggregated Sertoli cells in mounds generated during the morphogenetic cascade. We interpret the combined data to indicate that the appearance of laminin on the free surfaces of Sertoli cells is required to permit peritubular cells to adhere and subsequently to migrate on Sertoli cell surfaces, resulting in the formation of a tubule‐like structure. © 1994 Wiley‐Liss, Inc.
Effect of glucose on pHin and [Ca2+]in in NIH‐3T3 cells transfected with the yeast P‐Type H+‐ATPase
Authors: Martínez Gloria M. , Martínez‐Zaguilán Raul , Gillies Robert J. 
Published: February 2005

AbstractNIH‐3T3 cells transfected with yeast H+‐ATPases (RN1A cells) are tumorigenic (Perona and Serrano, 1988, Nature, 334: 438). We have previously shown that RN1a cells maintain a chronically high intracellular pH (pHin) under physiological conditions. We have alsoshown that RN1a cells are serum‐independent for growth, maintain a higher intracellular Ca2+(in), and glycolyze more rapidly than their non‐transformed counterparts (Gillies et al., Proc. Natl. Acad. Sci., 1990, 87: 7414; Gillies et al., Cell. Physiol. Biochem., 1992, 2: 159). The present study was aimed to understand the interrelationships between glycolysis, pHin, and [Ca2+]in in RN1a cells and their non‐transformed counterparts, NIH‐3T3 cells. Our data show that the higher rate of glycolysis observed in RN1a cell is due to the presence of low affinity glucose transporters. Consequently, the higher rate of glycolysis is exacerbated at high glucose concentration in RN1a cells. Moreover, the maximal velocity (Vmax) for glucose utilization is up to sixfold higher in RN1a cells than in the NIH‐3T3 cells, suggesting that the number of glucose transporters is higher in RN1a than NIH‐3T3 cells. Glucose addition to NIH‐3T3 cells results in modest decreases in both pHin and [Ca2+]in. In contrast, RN1a cells respond to glucose with a large decrease in pHin, followed by a large decrease in [Ca2+]in. The decrease in [Ca2+]in observed upon glucose addition is likely due to activation of Ca2+‐ATPase by glycolysis, since the Ca2+ decrease is abolished by the Ca2+ ATPase inhibitors thapsigargin and cyclopiazonic acid. Glucose addition to ATP‐depleted cells results in a decrease in [Ca2+]in, suggesting that ATP furnished by glycolysis is utilized by this pump. © 1994 Wiley‐Liss, Inc.
Role of intracellular Ca2+ stores in the regulation of electrogenic plasma membrane Ca2+ uptake in a B‐lymphocytic cell line
Authors: Marriott Ian , Bost Kenneth L. , Mason Michael J. 
Published: February 2005

AbstractExperiments were undertaken to investigate the role of intracellular Ca2+ stores in the regulation of Ca2+ uptake in the cultured B‐lymphocytic cell line CH12.LX.C4.5F5. Release of intracellular Ca2+ stores by addition of thapsigargin was accompanied by a biphasic increase in intracellular calcium concentration ([Ca2+]i). The initial rise in [Ca2+]i was due to release of Ca2+ from intracellular stores as determined by its maintenance in the absence of extracellular Ca2+. The secondary phase was (1) dependent on the presence of extracellular Ca2+, (2) inhibited by 5 mM extracellular Ni2+, and (3) inhibited by high K+, consistent with electrogenic Ca2+ uptake from the extracellular medium. In order to more accurate y investigate the electrogenic nature of this pathway we measured the membrane potential changes accompanying Ca2+ influx stimulated by release of Ca2+ from intracellular stores using bis(1,3‐diethylthiobarbituric acid trimethine) oxonol in Bapta‐loaded cells. Addition of 5 mM Ca2+ to cells pretreated with doses of thapsigargin or ionomycin shown to release intracellular Ca2+ stores induced a depolarization which was (1) dependent upon extracellular Ca2+, (2) abolished by 5 mM Ni2+, (3) independent of extracellular Na+, and (4) dependent upon Bapta loading. This depolarization was followed by a charybdotoxin‐sensitive repolarization consistent with secondary activation of K+ channels. Changes in [Ca2+]i monitored under identical conditions were monitored fluorimetrically using indo‐1 and were found to correlate with the changes in Em. On the basis of these data we conclude that an electrogenic Ca2+ ‐permeable pathway exists in this B‐lymphocytic cell line which is regulated by the degree of filling of an internal Ca2+ ‐store. © 1994 Wiley‐Liss, Inc.