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  • 1
    Electronic Resource
    Electronic Resource
    Global change of gene expression at late G1/S boundary may occur in human IMR-90 diploid fibroblasts during senescence (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 160 (1994), S. 531-538 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The hallmark of cellular aging is the failure of senescent diploid cells to enter or to complete the S phase of the cell cycle. The cause for such failure may hold the key for our understanding of the molecular basis of cellular aging. We have previously shown that aging of IMR-90 human diploid fibroblasts in culture is accompanied by a five to sevenfold decrease in both thymidine kinase activity and thymidine kinase mRNA level (Chang and Chen, 1988, J. Biol. Chem., 263: 11431-11435). To examine whether attenuation of gene expression at G1/S boundary is unique for thymidine kinase or it may involve most, if not all, of other G1/S genes, we compared the expressions of two classes of G1/S genes in young and in old IMR-90 cells following serum stimulation. We found that the expression of all these genes, including thymidylate synthase (TS), dihydrofolate reductase (DHFR), ribonucleotide reductase (PNR), proliferating cell nuclear antigen (PCNA), histone H1, histone H2A + 2B, histone H3, and histone H4, was induced to high levels in young IMR-90 cells but not in old IMR-90 cells. The mRNA levels of all G1/S genes in young cells were more than tenfold higher than that in old cells 12 hr after serum stimulation. The enzymes encoded by TS and DHFR genes and dUTPase also exhibited similar age-dependent attenuation in activities. In contrast, expression of growth-related genes such as elF-5A, c-Ha-ras, and β-actin did not show significant differences between young and old cells after serum stimulation. Computer analysis of the promoter region of these G1/S genes revealed an Sp-1 binding site as the most common cis-element. Taken together, our results suggest that the suppression of G1/S gene expressions during senescence may be a global phenomenon and that G1/S genes may be coordinately controlled. © 1994 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/jcp.1041600316
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  • 2
    Electronic Resource
    Electronic Resource
    Transient reduction in secreted 32 kD chitinase prevents somatic embryogenesis in the carrot (Daucus carota L.) variant ts11 (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 332-343 
    Details
    ISSN: 0192-253X
    Keywords: Somatic embryogenesis ; temperature-sensitive mutant ts11 ; chitinase ; carrot (Daucus carota L.) ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: At the nonpermissive temperature, somatic embryos of the temperature-sensitive (ts) carrot (Daucus carota L.) cell variant ts11 only proceed beyond the globular embryo stage in the presence of medium conditioned by wild-type cells. The causative component in the conditioned medium has been identified as an acidic 32 kD endochitinase. An antiserum raised against the 32 kD chitinase detected this protein in culture medium from ts11 embryo cultures grown at the permissive temperature as well as at the nonpermissive temperature. No difference in biochemical characteristics or in effect on ts11 embryo development could be detected between the 32 kD chitinase purified from wild-type cultures and the chitinase from ts11 cultures grown at the permissive or at the nonpermissive temperature. Compared to the amount present in a ts11 embryo culture at the permissive temperature, a reduction in the amount of 32 kD chitinase was observed during the temperature-sensitive period at the nonpermissive temperature. These results imply that the arrested embryo phenotype of ts11 is not the result of a structural difference in its 32 kD chitinase, but is the result of a transient decrease in the amount of 32 kD chitinase present. Morphological observations indicate that the ts11 phenotype is pleiotropic and also affects the cell wall of nonembryogenic cells. © 1995 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020160406
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  • 3
    Electronic Resource
    Electronic Resource
    Differential distribution of vesicular carriers during differentiation and synapse formation (1993)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 53 (1993), S. 251-264 
    Details
    ISSN: 0730-2312
    Keywords: coated vesicles ; monoclonal antibodies synapse formation ; nerve-muscle cultures ; immunofluorescent localization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Coated and noncoated vesicles participate in cellular protein transport. Both acetylcholine receptors (AChR) and acetylcholinesterase (AChE) are transported via coated vesicles, some of which accumulate beneath the neuromuscular synapse where AChRs cluster. To investigate the mechanisms by which these proteins are transported during postsynaptic remodeling, we purified coated vesicles from the bovine brain via column chromatography (Sephacryl S-1000) and raised monoclonal antibodies to epitopes of the vesicular membranes enriched in AChE. We assayed for AChE (coated vesicle enriched), hexosaminidase (lysosomal contaminants), NADH cytochrome C reductase (mitochondrial containing), and protein and demonstrated electron microscopically using negative staining that the vesicular fraction contained 95% pure coated vesicles. We then injected coated vesicle fractions and the fractions from which the coat was removed intraperitoneally into mice and obtained three monoclonal antibodies: C-33, C-172, and F-22. On immunoblots of purified vesicles and cultured skeletal muscle, mAb C-33 stained a 180 Kd band and mAb C-172 stained a 100 kd band. MAb F-22 stained 50 kd and 55 kd bands and was not characterized further. Immunofluorescent microscopy with C-33 and C-172 revealed punctate fluorescence whose distribution depends upon the stage of myotube development. Four days after plating, myotubes showed punctate fluorescence throughout the myotube, whereas those stained 8 days after plating showed a punctate perinuclear distribution. Myotubes innervated by ciliary neurons show punctate fluorescence limited to the nuclear periphery and most concentrated around nuclei which line up beneath neuronal processes. This differential vesicular distribution, observed during myotube differentiation and innervation, suggests that these vesicles participate in vesicular membrane traffic.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240530310
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  • 4
    Electronic Resource
    Electronic Resource
    The nucleus: A black box being opened (1991)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 47 (1991), S. 311-316 
    Details
    ISSN: 0730-2312
    Keywords: nuclear matrix ; MAR ; chromatin loops ; transcription ; RNA processing ; RNA transport ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Until recently our knowledge about the structural and functional organization of the cell nucleus was very limited. Recent technical developments in the field of ultrastrcutural analysis, combined with ongoing research on the properties of the nuclear matrix, give new insight into how the nucleus is structured. Two types of observations shape our ideas about nuclear organization. First, most nuclear functions (replication, transcription, RNA processing, and RNA transport) are highly localized within the nucleus, rather than diffusely distributed. Moreover, they are associated with the nuclear matrix. Second, chromatin is organized in discrete loops, bordered by nuclear matrix attachment sequences (MARs). Each loop may contain one or several genes. The arrangement of chromatin in loops has profound consequences for the regulation of gene expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240470405
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  • 5
    Electronic Resource
    Electronic Resource
    Reduced drug accumulation and multidrug resistance in human breast cancer cells without associated P-glycoprotein or MRP overexpression (1997)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 65 (1997), S. 513-526 
    Details
    ISSN: 0730-2312
    Keywords: mitoxantrone ; drug resistance ; non-Pgp MDR ; rhodamine ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: MCF-7 human breast cancer cells selected in Adriamycin in the presence of verapamil developed a multidrug resistant phenotype, which was characterized by as much as 100,000-fold resistance to mitoxantrone, 667-fold resistance to daunorubicin, and 600-fold resistance to doxorubicin. Immunoblot and PCR analyses demonstrated no increase in MDR-1 or MRP expression in resistant cells, relative to parental cells. This phenotype is similar to one previously described in mitoxantrone-selected cells. The cells, designated MCF-7 AdVp, displayed a slower growth rate without alteration in topoisomerase IIα level or activity. Increased efflux and reduced accumulation of daunomycin and rhodamine were observed when compared to parental cells. Depletion of ATP resulted in complete abrogation of efflux of both daunomycin and rhodamine. No apparent alterations in subcellular daunorubicin distribution were observed by confocal microscopy. No differences were noted in intracellular pH. Molecular cloning studies using DNA differential display identified increased expression of the alpha subunit of the amiloride-sensitive sodium channel in resistant cells. Quantitative PCR studies demonstrated an eightfold overexpression of the alpha subunit of the Na+ channel in the resistant subline. This channel may be linked to the mechanism of drug resistance in the AdVp cells. The results presented here support the hypothesis that a novel energy-dependent protein is responsible for the efflux in the AdVp cells. Further identification awaits molecular cloning studies. J. Cell. Biochem. 65:513-526. © 1997 Wiley-Liss Inc.
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  • 6
    Electronic Resource
    Electronic Resource
    PML-containing nuclear bodies: Their spatial distribution in relation to other nuclear components (1996)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 63 (1996), S. 280-291 
    Details
    ISSN: 0730-2312
    Keywords: nuclear bodies ; PML ; confocal microscopy ; image restoration ; RNA ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The PML protein is a human growth suppressor concentrated in 10 to 20 nuclear bodies per nucleus (PML bodies). Disruption of the PML gene has been shown to be related to acute promyelocytic leukaemia (APL). To obtain information about the function of PML bodies we have investigated the 3D-distribution of PML bodies in the nucleus of T24 cells and compared it with the spatial distribution of a variety of other nuclear components, using fluorescence dual-labeling immunocytochemistry and confocal microscopy. Results show that PML bodies are not enriched in nascent RNA, the splicing component U2-snRNP, or transcription factors (glucocorticoid receptor, TFIIH, and E2F). These results show that PML bodies are not prominent sites of RNA synthesis or RNA splicing. We found that a large fraction of PML bodies (50 to 80%) is closely associated with DNA replication domains during exclusively middle-late S-phase. Furthermore, in most cells that we analysed we found at least one PML body was tightly associated with a coiled body. In the APL cell line NB4, the PML gene is fused with the RARα gene due to a chromosomal rearrangement. PML bodies have disappeared and the PML antigen, i.e., PML and the PML-RAR fusion protein, is dispersed in a punctated pattern throughout the nucleoplasm. We showed that in NB4 cells the sites that are rich in PML antigen significantly colocalize with sites at which nascent RNA accumulates. This suggests that, in contrast to non-APL cells, in NB4 cells the PML antigen is associated with sites of transcription. The implications of these findings for the function of PML bodies are consistent with the idea that PML bodies are associated with specific genomic loci. © 1996 Wiley-Liss, Inc.
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  • 7
    Electronic Resource
    Electronic Resource
    Ultrastructural localization of active genes in nuclei of A431 cells (1996)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 62 (1996), S. 10-18 
    Details
    ISSN: 0730-2312
    Keywords: 5-bromouridine 5′-triphosphate ; electron microscopy ; domain ; nuclear matrix ; RNA polymerase II ; transcription ; ultrasmall gold ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We have studied the ultrastructural localization of active genes in nuclei of the human epidermoid carcinoma cell line A431. Nascent RNA was labeled by incorporation of 5-bromouridine 5′-triphosphate, followed by pre-embedment or postembedment immunogold labeling and electron microscopy using ultrasmall gold-conjugated antibodies and silver enhancement. This combination of techniques allowed a sensitive and high resolution visualization of RNA synthesis in the nucleus. Transcription sites were identified as clusters of 3-20 gold particles and were found throughout the nucleoplasm. The clusters had a diameter of less than 200 nm. The distribution of clusters of gold particles in nuclei is preserved in nuclear matrix preparations. Nascent RNA is associated with fibrillar as well as with granular structures in the matrix. A431 nuclei contained on average about 10,000 clusters of gold particles. This means that each cluster represents transcription of probably one active gene or, at most, a few genes. Our study does not provide evidence for aggregation of active genes. We found transcription sites distributed predominantly on the surface of electron-dense nuclear material, probably lumps of chromatin. This supports a model of transcription activation preferentially on the boundary between a chromosome domain and the interchromatin space. © 1996 Wiley-Liss, Inc.
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  • 8
    Electronic Resource
    Electronic Resource
    Major internal nuclear matrix proteins are common to different human cell types (1997)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 65 (1997), S. 42-52 
    Details
    ISSN: 0730-2312
    Keywords: nuclear matrix ; human cell types ; 2-D gel electrophoresis ; heterogeneous nuclear ribonucleoproteins ; B23 ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The nuclear matrix may be involved in the structural and functional organization of the cell nucleus. However, we still do not understand the molecular basis of the intranuclear network that is part of the nuclear matrix. We recently described a method to identify internal nuclear matrix proteins [Mattern et al. (1996): J Cell Biochem 62:275-289], which was done by comparing two nuclear matrix preparations: one with and one without the internal structure by using quantitative two-dimensional gel electrophoresis. In the present study, we use the same approach to compare the nuclear matrix proteins of four different human cell types to investigate whether they have a similar internal nuclear matrix protein composition. Major nuclear matrix proteins present in all these cell types likely represent the base of the internal nuclear matrix. We demonstrate that the 25 most abundant internal nuclear matrix proteins are common to all four cell types. Together, these common proteins represent more than 75% of the total internal nuclear matrix protein mass in each cell type. This set of proteins includes B23 and most hnRNP proteins. The quantity of most of these proteins is very similar in the four cell types. The fact that the internal nuclear matrix consists mainly of hnRNP proteins, which may be involved in transcription, transport, and processing of hnRNA, supports the idea that the internal nuclear matrix is the result of these processes. J. Cell. Biochem. 65:42-52. © 1997 Wiley-Liss, Inc.
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  • 9
    Electronic Resource
    Electronic Resource
    Nuclear neighbours: The spatial and functional organization of genes and nuclear domains (1998)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 70 (1998), S. 159-171 
    Details
    ISSN: 0730-2312
    Keywords: nucleus ; nuclear domain ; genome ; nucleolus ; coiled body ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: It is becoming clear that the cell nucleus is not only organized in domains but that these domains are also organized relative to each other and to the genome. Specific nuclear domains, enriched in different proteins and RNAs, are often found next to each other and next to specific gene loci. Several lines of investigation suggest that nuclear domains are involved in facilitating or regulating gene expression. The emerging view is that the spatial relationship between different domains and genes on different chromosomes, as found in the nucleolus, is a common organizational principle in the nucleus, to allow an efficient and controlled synthesis and processing of a range of gene transcripts. J. Cell. Biochem. 70:159-171. © 1998 Wiley-Liss, Inc.
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  • 10
    Electronic Resource
    Electronic Resource
    Involvement of heat shock elements and basal transcription elements in the differential induction of the 70-kDa heat shock protein and its cognate by cadmium chloride in 9L rat brain tumor cells (1998)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 71 (1998), S. 21-35 
    Details
    ISSN: 0730-2312
    Keywords: heat shock protein ; heat shock genes ; heat shock element ; heat shock factor ; basal transcription elements ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Exposure of 9L rat brain tumor cells to 40-100 μM CdCl2 for 2 h leads to an induction of a wide spectrum of heat shock proteins (HSPs). We have demonstrated that induction of the 70-kDa HSP (HSP70) and enhanced expression of its cognate (HSC70) by cadmium are concentration dependent and that the induction kinetics of these HSP70s are different. The increased synthesis of the HSP70s is accompanied by the increase in hsp70 and hsc70 mRNA levels, indicative of transcriptional regulation of the heat shock genes. Electrophoretic mobility shift assay (EMSA) using probes encompassing heat shock element (HSE), TATA, GC, and CCAAT boxes derived from the promoter regions of the heat shock genes shows distinguished binding patterns between hsp70 and hsc70 genes in both control and cadmium-treated cells. The results indicate that, in addition to the HSEs, the basal transcription elements are important in the regulation of the heat shock genes. The binding patterns of the corresponding transcription factors of these elements are examined by EMSA by using extended promoter fragments from respective heat shock genes with sequential addition of excess oligonucleotides encompassing individual transcription elements. Taken together, our results show that the differential induction of hsp70 and hsc70 involves multiple transcription factors that interact with HSE, TATA, GC, and CCAAT boxes. J. Cell. Biochem. 71:21-35, 1998. © 1998 Wiley-Liss, Inc.
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