bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nuclear‐Cytoskeletal interactions: Evidence for physical connections between the nucleus and cell periphery and their alteration by transformation
Authors: Pienta Kenneth J. , Coffey Donald S. 
Published: May 2005

AbstractThe overall coordination of cell structure and function that results in gene expression requires a spatial and temporal precision that would be unobtainable in the absence of structural order within the cell. Cells contain extensive and elaborate three‐dimensional skeletal networks that form integral structural components of the plasma membrane, cytoplasm, and nucleus. These skeletal networks form a dynamic tissue matrix and are composed of the nuclear matrix, cytoskeleton, and extracellular matrix. The tissue matrix is an interactive network which undergoes dynamic changes as cells move and change shape.Pathologists have long recognized cancer in pathologic specimens based on the altered morphology of tumor cells compared to their normal counterparts. The structural order of cells appears to be altered in transformed cells. This structural order is reflected in the altered morphology and motility observed in transformed cells compared to their normal counterparts, however, it is unclear whether the structural changes observed in cancer cells have any functional significance. We report here on the nature of the physical connections between the nucleus and cell periphery in nontransformed cells and demonstrate that the nucleus is dynamically coupled to the cell periphery via actin microfilaments. We also demonstrate that the dynamic coupling of the nucleus to the cell periphery via actin microfilaments is altered in Kirstenk‐ras transformed rat kidney epithelial cells. This loss of structure‐function relationship may be an important factor in the process of cell transformation.
A novel nuclear protein which binds to Gγ and Aγ globin promoters and modulates hemoglobin synthesis in K562 cells
Authors: Baliga B. S. , Phillips Karen , Aliabadi Zarrintaj , Mankad Vipul N. 
Published: May 2005

AbstractNuclear extract of human erythroleukemic cell line K562 contains a 70 kDa protein which is gradually reduced when cells are induced to express globin genes by 25 μM hemin. When globin synthesis was inhibited by cycloheximide (100 μg/ml) or Actinomycin D (1 μg/ml), the disappearance of this protein was prevented. The 70 kDa nuclear protein exhibited strong binding to Gγ and Aγ globin promoters but not to β‐globin promoter. This suggests that this 70 kDa nuclear protein may be involved in the regulation of fetal globin gene expression.
Evaluation of the role of electrostatic residues in human epidermal growth factor by site‐directed mutagenesis and chemical modification
Authors: Niyogi Salil K. , Campion Stephen R. , Tadaki Douglas K. 
Published: May 2005

AbstractFour residues in the carboxy‐termianl domain of human epidermal growth factor (hEGF), glutamate 40, glutamine 43, arginine 45, and aspartate 46 were targeted for site‐directed mutagenesis to evaluate their potential role in epidermal growth factor (EGF) receptor‐ligand interaction. One or more mutations were generated at each of these sites and the altered recombinant hEGF gene products were purified and evaluated by radioreceptor competition binding assay. Charge‐conservative replacement of glutamate 40 with asparate resulted in a decrease in receptor binding affinity to 30% relative to wild‐type hEGF. On the other hand, removal of the electrostatic charge by substitution of glutamate 40 with glutamine or alanine resulted in only a slightly greater decrease in receptor binding to 25% relative receptor affinity. The introduction of a positive charge upon substitution of glutamine 43 with lysine had no effect on receptor binding. The substitutiono of arginine 45 with lysine also showed no effect on receptor binding, unlike the absolute requirement observed for the arginine side‐chain at position 41 [Engler DA, Campion SR, Hauser MR, Cook JS, Niyogi, SK: J Biol Chem 267:2274–2281, 1992]. Subsequent elimination of the positive charge of lysine 45 by reaction with potassium cyanate showed that the electrostatic property of the residue at this site, as well as that at lysine 28 and lysine 48, was not required for receptor‐ligand association. The most highly conserved of the four residues studied in this report, aspartate 46, was replaced with alanine, tyrosine, and arginine, resulting in a decrease in relative receptor affinity to 23, 14, and 4 percent, respectively, and suggests the importance of an acidic group at this site of EGF. The ability to generate sufficient yields of mutant recombinant EGF protein was sensitive to the type of side‐chain substitutions generated at the sites described in this report and may indicate a role for these residues in the formation of the EGF structure apparently required for productive yields of EGF proteins in the expression system used in this study. © 1992 Wiley‐Liss, Inc.
Nucleoprotein complexes released from lymphoma nuclei that contain the abl oncogene and RNA and DNA polymerase and RNA primase activities
Authors: Rosenberg‐Nicoloson Nancy Lynn , Nicolson Garth L. 
Published: May 2005

AbstractWe report on the discovery and isolation of DNA‐ and RNA‐containing macromolecular nuclear complexes whose purified major DNA possessed electrophoretic mobilities of ∼ 90 and ∼ 25kbp. The deoxyribonucleoprotein‐ribonucleoprotein complexes conatin RNA and DNA polymerase and primase activities and were isolated from nuclei of murine RAW117 large‐cell lymphoma cells by restriction digestion with Msp‐1, gentle extraction with solutions containing MgCl2, but without chelating agents, and low ionic strength gel electrophoresis. Two‐dimensional (isoelectric focusing/Mr) gel electrophoresis and silver staining of the proteins of the complexes after treatment with DNase I indicated the presence of ∼ 30 protein components. In vitro DNA and RNA polymerase/primase assays showed that the DNP/RNP complexes had very high enzyme specific acticvites. Using the DNP/RNP complexes a discrete DNA polymerase α product of ∼ 85 kbp was synthesized that was not synthesized in the presence of the DNA polymerase α inhibitor aphidicolin. RNA polymerase assays in the presence of excess α‐amanitin indicated that the complexes possessed significant RNA polymerase I activity. Preparing the complexes at various times after the release of cells from a double thymidine block showed the complexes as well as the complex‐associated enzyme activities to be cell‐cycle dependent. The DNA and RNA polymerase‐related activities were highest in late S phase, 7 and 9 h, respectively, after release from the double thymidine block. The complexes synthesized a specific in vitro DNA polymerase product using endogenous substrate and nucleotide precursors. Hybridization sutides showed that the complexes contained the abl oncogene which is expressed in RAW117 cells, but not the β‐casein gene which is not expressed in this cell system. © 1992 Wiley‐Liss, Inc.
Adipogenesis in a myeloid supporting bone marrow stromal cell line
Authors: Gimble Jeffery M , Youkhana Kellee , Hua Xianxin , Medina Kay , Sullivan Mary , Bass Helen , Wang Chi‐Sun , Greenberger Joel 
Published: May 2005

AbstractThe bone marrow stroma contains pre‐adipocyte cells which are part of the hemopoietic microenvironment. Cloned stromal cell lines differ both in their ability to support myeloid and lymphoid development and in their ability to undergo adipocyte differentiation in vitro. These processes have been examined in the +/+2.4 murine stromal cell line and compared to other stromal and pre‐adipocyte cell lines. In long term cultures, the +/+2.4 stromal cells support myeloid cell growth, consistent with their expression of macrophage‐colony stimulating factor mRNA. However, despite the presence of mRNA for the lymphoid supportive cytokines interleukins 6 and 7, +/+2.4 cells failed to support stromal cell dependent B lineage lymphoid cells in vitro, suggesting that these stromal cells exhibit only a myelopoietic support function. The +/+2.4 cells differentiate into adipocyte spontaneously when cultured in 10% fetal bovine serum. The process of adipogenesis can be accelerated by a number of a agonists based on morphologic and gene maker criteria. Following induction with hydrocortisone, methylisobutylxanthine, indomethacin, and insulin in combination a time dependent increase in the steady state mRNA and enzymes activity levels of the following adipocyte specific genes was observed: adipocyte P2, adipsin, CAAT/enhancer binding protein, and lipoprotein lipase. In contrast, adipogenesis were accompanied by a slight decrease in the signal intensity of the macrophage‐colony stimulating factor mRNA level, similar to that which has been reported in other bone marrow stromal cell lines. These data demonstrate that although the lympho‐hematopoietic support fuction of pre‐adipocyte bone marrow stormal cell lines is heterogeneous, they share a common mechanism of adipognensis. © 1992 Wiley‐Liss, Inc.
Homeotic protein binding sites, origins of replication, and nuclear matrix anchorage sites share the ATTA and ATTTA motifs
Authors: Boulikas Teni 
Published: May 2005

AbstractNuclear matrix organizes the mammalian chromatin into loops. This is achieved by binding of nuclear matrix proteins to characteristic DNA landmarks in introns as well as proximal and distal sites flanking the 5′ and 3′ ends of genes. Matrix anchorage sites (MARs), origins of replication (ORIs), and homeotic protein binding sites share common DNA sequence motifs. In particular, the ATTA and ATTTA motifs, which constitute the core elements recognized by the homeobox domain from species as divergent as flies and humans, are frequently occurring in the matrix attachment sites of several genes. The human apolipoprotein B 3′ MAR and a stretch of the Chinese hamster DHFR gene intron and human HPRT gene intron shown to anchor these genes to the nuclear matrix are mosaics of ATTA and ATTTA motifs. Several origins of replication also share these elements. This observation suggests that homeotic proteins which control the expression level of many genes and pattern formation during development are components of the nuclear matrix. Thus, the nuclear matrix, known as the site of DNA replication, might sculpture the crossroads of the differential activation of origins during development and S‐phase and the control of gene expression and pattern formation in embryogenesis. © 1992 Wiley‐Liss, Inc.
The rapid nongenomic actions of 1α,25‐dihydroxyvitamin D3 modulate the hormone‐induced increments in osteocalcin gene transcription in osteoblast‐like cells
Authors: Baran Daniel T. , Sorensen Ann Marie , Shalhoub Victoria , Owen Thomas , Stein Gary , Lian Jane 
Published: May 2005

AbstractWe have previously shown that one of the rapid nongenomic actions of 1α,25‐dihydroxyvitamin D3 (1α,25‐(OH)2D3), the increase in intracellular calcium (Ca2+), accompanies the increased osteocalcin (OC) mRNA steady‐state levels in rat osteosarcoma cells. To determine the functional significance of the nongenomic actions, we have measured changes in intracellular Ca2+ as an indicator of the rapid effects and have assessed the effect of inhibition of the rapid increase in cellular Ca2+ by the inactive epimer, 1β,25‐dihydroxyvitamin D3 (1β,25‐(OH)2D3) on OC mRNA steady‐state levels and transcription. 1β,25‐dihydroxyvitamin D3 inhibited 1α,25‐(OH)2D3 induced increases in intracellular Ca2+ and OC mRNA transcription at 1 hr and OC mRNA steady state levels at 3 hr. 1β,25‐Dihydroxyvitamin D3 did not alter the binding of the vitamin D receptor complex to the vitamin D responsive element of the OC gene. The results demonstrate the functional importance of the rapid, nongenomic actions of 1α,25‐(OH)2D3 in the genomic activation of the OC gene by the hormone in rat osteoblast‐like cells, perhaps by modifying subtle structural and/or functional properties of the vitamin D–receptor DNA complex or by affecting other protein DNA interactions that support OC gene transcription. © 1992 Wiley‐Liss, Inc.
The mammalian iris‐ciliary complex affects organization and synthesis of cytoskeletal protein of organ and tissue cultured lens epithelial cells
Authors: Banergee Amit , Emanuel Karen , Parafina Julian , Bagchi Mihir 
Published: May 2005

AbstractA water soluble growth inhibitor was isolated from the mammalian ocular iris‐ciliary complex. The molecular weight of this protein is 10 kD or lower as determined by ultrafiltration fractionation. The iris‐ciliary (IC) complex water soluble protein(s) significantly inhibits synthesis of lower molecular weight protein of the epithelial cells of the organ cultured mammalian ocular lens. It was also found that this inhibitory effect of IC is mediated via the structural organization of the lens. Monolayer cultures of the lens epithelial cells exposed to IC did not manifest any inhibiton of their protein synthesis. Moreover, these tissue cultured lems epithelial (TCLE) cells showed a significant increase in their protein synthetic activities in response to the presence of IC factors in the culture medium. It is postulated that the IC activity is modulated via either the lens capsule, an extracellular matrix, or due to the specific organization of the intact lens.The specific effects of IC on the cytoskeletal organization and synthesis in the organ cultured lens epithelial (OCLE) and TCLE cells were also examined. Both groups, treated with IC factors, manifested significant alterations in their protein synthetic activities and cytoskeletal architecture. The 3H‐leucine incorporation experiments showed that α‐actin and α‐tubulin synthesis is partially inhibited by IC factors in OCLE cells by vimentin synthesis is not, whereas in TCLE cells all of them showed increased synthesis in response to IC factors. Turnover rates of these proteins in both OCLE and TCLE cells were also computed. The immunofluorescence and microscopic evaluation of OCLE and TCLE cells exposed to IC factors illustrated significant alteration in the cytoarchitecture of the filaments. We demonstrate that an inhibitor(s) molecule of 10 kD or lower size isolated from IC inhibited protein synthesis of OCLE cells and stimulated protein synthesis in TCLE cells. The IC factor also affects the synthesis and organization of cytoskeletal filaments of both the OCLE and TCLE cells. © 1992 Wiley‐Liss, Inc.
Comparison of the mouse L32 ribosomal protein promoter elements in mouse myoblasts, fibers, and L cells
Authors: Harris Steven A. , Bowman Lewis H. , Dudov Kalin P. 
Published: May 2005

AbstractThe sequences required for the maximal expression of the mouse L32 ribosomal protein gene and the binding of nuclear factors to L32 promoter elements were analyzed in mouse myoblasts, fibers, and L cells. Various L32 r‐protein promoter sequences were linked to the chloramphenicol acetyltransferase gene (CAT), and the expression of the chimeric genes was measured transiently or after their incorporation into the genome. The sequence requirements for maximal expression of the L32 gene are very similar among the various cells and include the previously identified L32 core promoter from ≈ −150 to +75. Only the promoter region between −45 and +11 displays significant cell type specific differences. Relative to the maximal activity in each cell type, the expression of the L32‐CAT gene containing the −45 to +11 region is greater in L cells than in myoblasts or fibers. This difference is correlated with the increased activity of an L cell nuclear factor(s) that binds to this fragment. In addition, our results show that deletion of sequences between −981 and −141 causes a 50–70% reduction of the expression of the L32‐CAT gene in myoblasts, fibers, and L cells. The transcription of all the L32 gene, but we were unable to distinguish between sequences involved in controlling the expression of the L32 gene during myoblast differentiation and those sequences required for maximal promoter activity. However, gel mobility shift assays showed differences in the binding of myoblast and fiber factors to the four promoter fragments examined. The possible role of these factor binding differences in controlling L32 transcription is discussed. © 1992 Wiley‐Liss, Inc.
Cholera toxin potentiates TPA‐induced mitogenesis and c‐fos expression in BALB/c‐3T3‐derived proadipocytes
Authors: Smyth Miriam J. , Runnels Beth , Wharton Walker 
Published: May 2005

AbstractTreatment of quiescent density‐arrested A31T6 proadipocytes with medium supplemented with either 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA), insulin, or cholera toxin alone did not simulate G0/G1 traverse and initiation of DNA synthesis. Combinations of either TPA and cholera toxin or insulin and cholera toxin caused a small stimulation of proliferation. Addition of medium supplemented with TPA and insulin caused a marked stimulation of cell cycle traverse which was significantly potentiated by the coaddition of cholera toxin. The actions of cholera toxin were mimicked by forskolin. Expression of c‐fos was regulated in a manner that reflected the results of the mitogenic experiments. TPA caused a marked induction of expression, while only a small increase in transcript levels was seen after treatment with cholera toxin. Addition of a combination of cholera toxin and TPA caused a synergistic induction of c‐fos expression. The model system described in this paper allows a detailed analysis of the regulation, by independent second messenger system, of the transcription of a gene in a mitogenically relevant manner. © 1992 Wiley‐Liss, Inc.
Density‐Dependent modulatioon of vascular smooth muscle α‐actin biosynthetic processing in differntiated BC3H1 myogenic cells
Authors: Strauch Arthur R. , Min Bonhong , Reeser Jonathan C. , Yan Hua , Foster Douglas N. , Berman Mark D. 
Published: May 2005

AbstractThe expression of vasuclar smooth muscle (VSM) α‐actin mRNA during BC3H1 myogenic cell differentiation is specifically stimulated by conditions of high cell density. Non‐proteolytic dissociation of cell‐cell and cell‐matrix contacts in post‐confluent cultures of BC3H1 myocytes using EDTA promotes loss of the differentiated morphological phenotype. EDTA‐dispersed myocytes exhibit an undifferentiated fibroblastoid appearance and contained reduced levels of both VSM and skeletal α‐actin mRNA. Muscle α‐actin mRNA levels in EDTA‐dispersed myocytes were not restored to that observed in confluent myocyte preparations by experimental manipulation of cell density conditions. Pulse‐labeling techniques using L‐[35S] cysteine to identify muscle actin biosynthetic intermediates revelated that EDTA‐dispersed myocytes expressed nascent forms of both the VSM and skeletal muscle α‐actin polypetide chains. However EDTA‐dispersed myocytes were less effieicent in the post‐translational processing of immautre VSM α‐actin compared to non‐dispersed myocytes. Simple cell‐to‐cell contact may mediate VSM α‐actin processing efficiency since high‐density preparations of EDTA‐dispersed myocytes processed more VSM α‐actin intermediate than myocytes plated at low density. The actin isoform selectivity of the response to modulation of intercellular contacts suggests that actin biosynthesis in BC3H1 myogenic cells involves mehcanisms capable of discriminating between different isoform classes of nascent actin polypetide chains. © 1992 Wiley‐Liss, Inc.
Nucleoproteins derived from subnuclear RNA polymerase complexes of metastatic large‐cell lymphoma cells possess transcription activities and regulatory properties in vitro
Authors: Rosenberg‐Nicolson Nancy Lynn , Nicolson Garth L. 
Published: May 2005

AbstractIntact nuclei derived from poorly or highly liver‐metastatic murine large‐cell lymphoma cell line RAW117 were digested to discrete subchromatin deoxyribonucleoprotein/ribonucleoprotein (DNP/RNP) complexes with Msp‐1. The DNP/RNP complexes were composed of DNP/RNPs which were derived from the DNP/RNP complexes by incubation in the presence or absence of DNase‐1 and subsequent isolation by two‐dimensional [isoelectric focusing/sodium dodecylsulfate (SDS)] polyacrylamide gel electrophoresis (PAGE), electroelution from the gel, and removal of SDS. Approximately 450 DNP/RNPs in the two‐dimensional gels corresponding to discrete spots or in some cases streaks were analyzed for the presence of v‐abl, p53, c‐neu, c‐H‐ras, β‐casein, 18s rDNA, and μ‐chain immunoglobulin genes using a hybridization technique. Ten DNP/RNP complexes contained tightly associated p53 DNA, whereas six contained c‐ or v‐abl, four contained μ‐chain gene, two contained c‐H‐ras, one contained dot‐blot β‐casein, two contained 18s rDNA, and c‐neu was found in one of the DNP/RNPs. The DNP/RNPs were also analyzed for in vitro RNA polymerase and primase activities. To assess the potential transcription abilities of the isolated DNP/RNPs, individual DNP/RNPs or DNP/RNP mixtures (reconstituted after SDS‐PAGE separation) were examined for RNA polymerase initiation and synthesis. When RNA products were formed, these were purified by extracellulose chromatography and used as back‐hybridization probes for the genes of interest. The RNA products were also analyzed by RNA gel electrophoresis. RNA formation was inhibitable by actinomycin D, and the RNAs formed ranged in size from ∼ 80 kbp to ∼ 1 kbp. By mixing various DNP/RNP complexes together, different patterns of RNA synthesis were found. For example, one DNP/RNP of Mr ∼ 140,000, isoelectric point(pl) ∼ 5.8 synthesized a high molecular weight RNA in vitro that hybridized with β‐casein cDNA, but β‐casein is not expressed in RAW117 cells, suggesting that the silencing of the β‐casein gene was negated by isolation of the DNP/RNP. Mixing this DNP/RNP with two other specific DNP/RNPs again inhibited the synthesis of β‐casein RNA, suggesting that interactions between DNP/RNP complexes can result in differential RNA expression or regulation of RNA polymerases in vitro. © 1992 Wiley‐Liss, Inc.
Differential expression of the histone H1° gene in U937 and HL‐60 leukemia cell lines
Authors: Hochhuth C. , Doenecke D. 
Published: May 2005

AbstractThe expression of the human H1° histone gene and of a main type H1 gene was analyzed in two human leukemia cell lines. The main type, replication dependent H1 gene expression reflected the state of proliferation of both cell lines. No H1° mRNA was detected in the promyelocytic HL‐60 line, whereas the monocytic U937 cells showed low steady‐state levels of H1° mRNA. Stimulation of HL‐60 with several known induces of differentiation failed to induce any accumulation of H1°. mRNA. Treatment of U937 with phorbol ester or butyrate, on the other hand, led to an increase of the H1° mRNA concentration. © 1992 Wiley‐Liss, Inc.