Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0026764 (multiple myeloma)
 36,148 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Initial results of an approach to the isolation of functionally active chromatin are described. Slight digestion of mouse myeloma nuclei at 0 degrees C with micrococcal nuclease, followed by dialysis against near-physiological saline solution containing 1 mM Mg2+, caused release of up to 17% of the nuclear DNA as soluble nucleoproteins. This soluble (S) fraction was relatively depleted in H1 histones and methylated DNA (5-methylcytosine) but highly enriched in RNA, single-stranded DNA, and nonhistone chromosomal proteins, particularly two species of the high mobility group identified as HMG 1 and HMG 2. The S fraction released most rapidly (6--8% of the total DNA) consisted mainly of mono- and small oligonucleosomes. The mononucleosomes appeared normal in terms of sedimentation behavior, DNA length, and content of histones H2A, H2B, H3, and H4, but lacked H1, and instead were associated with approximately stoichiometric amounts of HMG 1 and HMG 2. Studies using isolated, fluorescence-labeled, total mouse HMG proteins indicated that added HMG 1 and HMG 2 do not bind strongly to S-fraction nucleoproteins but that two smaller HMG species (probably HMG 14 and HMG 17) do bind preferentially to S-fraction mono- and dinucleosomes. These results argue against artifactual redistribution of HMG 1 and HMG 2 during this fractionation but suggest caution in interpreting the distribution of smaller HMG proteins after digestion of chromatin. The potential relationship of this soluble fraction to transcriptionally active chromatin is discussed.
 ...
PMID:Chromatin fractionation procedure that yields nucleosomes containing near-stoichiometric amounts of high mobility group nonhistone chromosomal proteins. 47 83

If micrococcal nuclease is allowed to digest chromatin as it exists inside intact nuclei isolated from mouse myeloma tissue culture cells, more than 60% of the DNA can be isolated as a homogeneous fragment on a sucrose gradient. Analytical ultracentrifugation indicates that the protected DNA is native, unnicked, and about 140 +/- 10 base pairs long. After less extensive nuclease digestion, the protected DNA migrates in gels in lengths which are integral multiples of this 140 base pair "monomer" band. A submonomer band, 105 "/- 10 base pairs long, can also be detected. Similar digestion patterns were obtained by two different nuclear isolation procedures and even when intact cells were gently lysed directly in the digestion medium. These results confirm and extend the chromatin digestion studies of previous investigators and provide support for a subunit model for eukaryotic chromatin. The single strand specific S1 nuclease did not digest intranuclear chromatin under the conditions used.
 ...
PMID:Evidence for a subunit structure of chromatin in mouse myeloma cells. 117 64

Mouse thymidine kinase negative (tk-) L-cells were cotransformed with two different kappa light chain genes (cloned from mouse myeloma) and the tk gene from Herpes simplex virus I. (Transformation is defined as change in the genotype by introduction of foreign DNA.) About 80% of the tk+ -transformants contained varying amounts of transferred kappa light chain sequences, one transformant about 150 copies per genome. The transferred immunoglobulin genes appear to be organized in a nucleosomal substructure, as deduced from digestion experiments with micrococcal nuclease. In situ hybridization experiments revealed, that the transferred genes are not distributed randomly across the chromosomes of the recipient cell. Instead they are clustered at one or a few chromosomal locations.
 ...
PMID:Localization in mouse-L-Cell chromosomal sites of transferred immunoglobulin genes. 628 Sep 34

In mouse myeloma T the productive kappa light chain gene differs from its aberrantly rearranged allele in the patterns of DNAase I hypersensitive sites. In the region of the alleles where they are identical in sequence they have one site in common which lies 0.8 kb downstream of the coding region; but two sites upstream of and within the C gene segment (2) are found only on the non-productive allele. Within the region of different sequences both alleles have analogously located DNAase I hypersensitive sites; they lie 0.15 kb upstream of the respective leader segments and cover putative promoter sequences. Only one of the six DNAase I hypersensitive sites is also very sensitive towards micrococcal nuclease due to its particular DNA sequence. The non-rearranged gene studied in liver nuclei has no DNAase I hypersensitive sites but is preferentially cleaved in A/T rich regions.
 ...
PMID:Differences in the nuclease sensitivity between the two alleles of the immunoglobulin kappa light chain genes in mouse liver and myeloma nuclei. 628 16

Fragmentation of the actively transcribed kappa immunoglobulin gene in mouse myeloma nuclei with micrococcal nuclease and the restriction nuclease Bsp RI reveals a chromatin structure without the regularity of repeating nucleosomes found in bulk chromatin. Such regularity is restored about 2.2 kb 3' of the coding region. An only moderately increased micrococcal nuclease sensitivity and a 65% average protection of the Bsp RI sites indicates a DNA-protein interaction in the transcribed region which is not very different from that of an inactive gene. As determined by indirect endlabeling the frequency of Bsp RI cleavage both, after very mild and exhaustive digestion, varied moderately from site to site along the gene. In addition, it was not in each case the same at analogous sites on both alleles which are both transcribed. Thus, the experiments demonstrate differences between the chromatin structures of the genes which may be related to regulatory phenomena and thereby corroborate earlier findings made with DNAase I.
 ...
PMID:Protection of expressed immunoglobulin genes against nuclease cleavage. 630 36

A chromatin fraction solubilized from mouse myeloma nuclei under near-physiological ionic conditions by very mild micrococcal nuclease digestion at 0 degrees C is enriched at least 7-fold in DNA complementary to total myeloma polyadenylated mRNA, and 15-fold in DNA originating near the replication fork (labeled within 30 s). Newly replicated DNA recovered in solubilized chromatin after brief labeling was incorporated mainly into particles sedimenting with, or faster than, mononucleosomes. A rapid decrease in enrichment of newly replicated DNA in readily released, soluble chromatin with increasing labeling times indicated that newly replicated chromatin matured within 90 s to a form that was partitioned similarly to bulk chromatin by this fractionation method. Previous studies showed that chromatin readily solubilized from myeloma nuclei is enriched in high-mobility-group (HMG) and other non-histone proteins, RNA and single-stranded DNA; and depleted in H1 and 5-methylcytosine, relative to bulk chromatin (Jackson, J.B., Pollock , J.M., Jr., and Rill , R.L. (1979) Biochemistry 18, 3739-3748). Mild digestion of chicken erythrocyte nuclei with micrococcal nuclease yielded a soluble chromatin fraction (1-2% of the total DNA) with similar properties. This fraction was enriched at least 6-fold in DNA complementary to chicken globin mRNA, relative to total erythrocyte DNA.
 ...
PMID:Enrichment of transcribed and newly replicated DNA in soluble chromatin released from nuclei by mild micrococcal nuclease digestion. 654 59

Mono- and dinucleosomes preferentially cleaved from mouse myeloma chromatin by very mild micrococcal nuclease digestion at 0 degree C are soluble and are released from nuclei under near-physiological conditions in which normal nucleosomes containing Hl are insoluble. These nucleosomes are highly enriched in RNA, high-mobility-group proteins and a unique subset of other non-histone proteins. They are nearly devoid of histone Hl and contain DNA significantly less methylated than whole myeloma DNA, indicating that they comprise a subset of genomic sequences. Previously we have shown that this fraction is enriched in transcribed DNA sequences. Non-histone proteins that co-sedimented with readily solubilized nucleosomes included many of the most basic, low-to-moderate molecular weight chromosomal proteins. Many of these proteins were also preferentially acetylated in vivo. The residual, pelleted chromatin was highly enriched in high molecular weight proteins (greater than 60 000), and very depleted in medium molecular weight proteins. Readily solubilized nucleoproteins sedimenting like mononucleosomes were partly resolved by electrophoresis, under non-denaturing conditions, into several subfractions differing significantly in non-histone protein contents. Methods described here should be useful for identifying and isolating non-histone proteins bound to nucleosomes and other chromatin regions that are structurally and functionally unique.
 ...
PMID:Non-histone proteins of soluble nucleoproteins released from mouse myeloma nuclei by mild micrococcal nuclease digestion. 672 66

A comparative study of several parameters of the cell nuclei of hybridoma MLC-1c and its parent cells--myeloma X-63.Ag8.653 and spleen lymphocytes of Balb/c mice, has been carried out. The results of cytogenetic studies suggest that although the hybridoma and myeloma cell lines used in this study are rather stable, they contain some proportion of the altered chromosomal material. Two-dimensional electrophoresis performed according to O'Farrell revealed that the similarity between the relative presentation and reciprocal location of the nuclear proteins expressed by the myeloma and the hybridoma was greater than that between these cell lines and lymphocytes. Probing of the chromatin structure by micrococcal nuclease showed no significant differences in the degree of nuclease resistance of chromatin between myeloma, hybridoma and lymphoid cells. A comparative study of the Ca/Mg-dependent endonuclease activity of the nuclei in situ and in nuclear extracts demonstrated that whereas its content in lymphocytes was rather high, in myeloma and hybridoma it was practically absent. At the same time, cell nucleus extracts of the myeloma and the hybridoma contained high amounts of DNA-binding proteins which were undetectable in mouse spleen lymphocytes.
 ...
PMID:[Comparative characteristics of some parameters of the cell nucleus in the series myeloma-hybridoma-lymphocyte]. 848 24

The purine analogue, 8-chloro-adenosine (8-Cl-Ado), induces apoptosis in a number of multiple myeloma (MM) cell lines. This ribonucleoside analogue accumulates as a triphosphate and selectively inhibits RNA synthesis without perturbing DNA synthesis. Cellular RNA is synthesized by one of three polymerases (Pol I, II, or III); thus, the inhibition of one or more RNA polymerases may be mediating 8-Cl-Ado cytotoxicity. Here, we have addressed this question by dissecting the RNA-directed actions of 8-Cl-Ado in MM cells. Differential alterations in [(3)H]uridine incorporation were found in the three major classes of RNA after a 20-h exposure with 10 microM 8-Cl-Ado. The synthesis rate of Pol III transcripts, 5 S and tRNA, remained unchanged, whereas Pol I-mediated rRNA synthesis decreased by approximately 20%. In contrast, mRNA synthesis, which is transcribed by Pol II, rapidly declined within 4 h and reached a 50% decrease, which was maintained for 20 h. Parallel to RNA synthesis inhibition, 8-Cl-Ado was maximally incorporated in the mRNA (>13 nmol/mg RNA), which was 5-fold higher than the tRNA and rRNA incorporation. Electrophoretic and radiographic analysis of newly synthesized and processed [(14)C]uridine-labeled transcripts indicated that the analogue blocks transcription elongation. Consistent with that result, high-performance liquid chromatography analysis of micrococcal nuclease and spleen phosphodiesterase-digested RNA demonstrated that the analogue incorporation is at the 3' terminus. In conclusion, our data demonstrate that in MM cells, 8-Cl-Ado is preferentially incorporated into mRNA, suggesting a propensity toward Pol II, and inhibits RNA synthesis by premature transcriptional chain termination.
 ...
PMID:RNA-directed actions of 8-chloro-adenosine in multiple myeloma cells. 1463 28

To investigate the molecular mechanisms of action of the nitrogen mustard melphalan in patients treated for multiple myeloma, the in vivo induction and repair of melphalan-induced DNA damage was measured in genes with different transcriptional activity (b-actin>p53>N-ras>d-globin) from leukocytes of 20 multiple myeloma patients following chemotherapeutic administration of high-dose melphalan (200mg/m(2)) and autologous blood stem cell transplantation. Heterogeneous repair was found among the studied genes. The extent of repair was always in the order: b-actin>p53>N-ras>d-globin, correlating with the gene transcriptional state. Similar findings were obtained using peripheral blood mononuclear cells (PBMC) from healthy volunteers following in vitro treatment with melphalan, indicating that these results are not malignant disease-specific. Following in vitro treatment of PBMC from healthy volunteers with alpha-amanitin, an inhibitor of RNA polymerase II that can also induce condensation of chromatin structure, a significant inhibition of the removal of melphalan-induced damage in the three active genes but not in the silent d-globin gene was found, suggesting that transcription and/or chromatin structure may play important roles in the preferential DNA repair. When the in vivo DNA damage formation and repair in multiple myeloma patients following chemotherapeutic administration of melphalan was measured in the two strands of the active genes, no strand bias was found, indicating that the global genome repair subpathway of nucleotide excision repair may play a crucial role in the repair of these adducts. These results were also confirmed in PBMC from healthy volunteers following in vitro treatment with melphalan. Using micrococcal nuclease digestion of nuclei isolated from PBMC of multiple myeloma patients before the chemotherapeutic treatment, as well as from PBMC of healthy volunteers, we probed the chromatin structure in each gene and found that the "looseness" of the chromatin structure correlated with the levels of the gene-specific repair, being again in the order: b-actin>p53>N-ras>d-globin. To conclude, the in vivo gene-specific repair of melphalan-induced damage in humans is greatly affected by the local chromatin structure.
 ...
PMID:Preferential in vivo DNA repair of melphalan-induced damage in human genes is greatly affected by the local chromatin structure. 1678 Nov 99


1