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Query: UMLS:C0026764 (multiple myeloma)
 36,148 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cultured MPC 11 mouse myeloma cells synthesize not only gamma2b heavy and kappa light chains but also a carboxyl terminal (constant region) fragment of kappa light chain. In vitro translational analysis of total cytoplasmic and microsomal RNA indicates that these cells contain RNA which directs synthesis of both a light chain precursor and a light chain fragment precursor. Variant clones which do not synthesize either heavy or light chains continue to synthesize the light chain fragment. One such "nonproducing" variant was studied in detail. It does not contain translatable mRNA for the intact light chain but does contain RNA which is translated into the light chain fragment precursor. Nucleic acid hybridization analysis with a cDNA probe specific for the constant region of kappa light chains revealed that microsomal RNA from the wild-type cell contains both 14S and a 10S species of kappa specific RNA, whereas the variant contains only the 10S species. Translational analysis of these same RNAs indicates that the 14S species codes for the light chain precursor, while the 10S RNA codes for the light chain fragment precursor.
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PMID:Characterization of light chain and light chain constant region fragment mRNAs in MPC 11 mouse myeloma cells and variants. 80 46

Crude preparations of biologically active mRNA, which code for a myeloma (MPC-11) light chain, were isolated by two successive sucrose gradient centrifugations of RNA extracted from membrane-bound ribosomes, mRNA thus obtained was separated into a poly(A)-rich and a poly(A)-poor fraction by oligo(dT)-cellulose chromatography. Both these fractions were able to direct the synthesis of light chains in reconstituted cell-free systems derived from heterologous cells (ascites tumor lysates) and homologous cells (MPC-11 cells grown in suspension culture). The identity of the products in vitro was confirmed by comparing their migration with that of light chains produced in vivo upon electrophoresis in sodium dodecylsulphate/polyacrylamide gels, and from the profiles of tryptic peptides obtained by chromatography on Aminex A-5 ion-exchange columns. Template activity of the poly(A)-rich light chain mRNA fraction showed very little variation during the cell cycle. The activity of the poly(A)-poor fraction on the other hand was maximal during the early S phase. It is concluded that maximal synthesis of immunoglobulins observed in vivo during the late G1 phase of the cell cycle is achieved by translational control mechanisms.
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PMID:Cell-free translation of messenger RNA for a myeloma light chain prepared from synchronised plasmacytoma cells. 81 70

Immunoglobulin kappa-chain mRNA was hybridized with DNA in order to assess the kappa-gene frequency. Kappa-mRNA was purified from membrane-bound ribosomes of mouse myeloma MOPC-41 by poly (U) chromatography and isolation of a 13S RNA by successive sucrose density gradient centrifugations. The RNA coded for kappa-chain precursor molecules in cell-free protein synthesis and essentially no other proteins. MOPC-41 kappa-mRNA hybridized with MOPC-41, MPC-11, and Krebs DNA with the same kinetics: the majority of the hybrids was formed with rare or unique DNA sequences (Cot/2 450 to 900), a small portion with highly repetitive sequences (Cot/2 5--6). The slow hybrids were well matched and the rapid hybrids were mismatched by about 4%, regardless of the DNA used. It was further investigated whether the rapid hybrids contained translatable kappa-mRNA or were due to impurities in the RNA preparations. Kappa-mRNA and globin-mRNA (as an internal standard for a unique transcript) were hybridized with DNA to Cot 20 or 48, the hybridized and unhybridized RNA were isolated by hydroxyopatite-urea chromatography and, after removal of the DNA, translated in a cell-free system. The cell-free products were analyzed by SDS-polyacrylamide gel electrophoresis and immunoprecipitation. It was found that approximately equal quantities of translatable kappa- and globin-mRNA were hybridized maximally 1.7%). The results do not support the hypothesis that kappa-mRNA is a transcript of both repetitive and unique DNA sequences.
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PMID:Analysis of immunoglobulin genes: DNA/RNA hybridization with immunoglobulin kappa-chain mRNA and isolation and translation of hybridized RNA. 81 83

The pathways and kinetics of interchain disulfide bond formation have been determined in vitro for purified myeloma proteins representing the three major subclasses of mouse immunoglobulin G(IgG) using the reoxidation system described previously (Petersen, J.G.L. & Dorrington, K.J. (1974) J. Biol. Chem. 249, 5633-5641). Mixtures of oxidized and reduced glutathione were added to act as a disulfide interchange catalyst. The pathways of covalent assembly observed in vitro were qualitatively and quantitatively similar to those followed by the various subclasses in vivo. HH and HHL were the principle covalent intermediates seen with IgG1 (MOPC 31C) and IgG2a (MOPC 173 and clone 19). With IgG2b( MPC 11C), HL, HH and HHL were all prominant intermediates. The time courses of reoxidation were simulated using a theoretical model based on second-order reaction kinetics (Percy, J.R., Percy, M.E. & Dorrington, K.J. (1974) J. Biol. Chem. 250, 2398-2400). Two distinct phases were apparent in the reoxidation sequence. The first, which lasted for the initial 5-15 min, did not confirm to the theoretical model. The second phase could be accounted for by the model and represented the remainder of the covalent assembly process. The physico-chemical basis for this biphasic phenomenon was explored. Sedimentation velocity studies showed that noncovalent association was incomplete at the beginning of the reoxidation step for all proteins except IgG2b (MOPC 11C). No dissociation was apparent in the reduced and alkylated proteins at pH 5 in the absence of prior exposure to acid conditions. Thus, exposure to acid appears to affect the affinity between the subunits in the native proteins. Transfer of the proteins from pH 5 to pH 8.2 (the pH at which reoxidation proceeds) is accompanied by the generation of an absorption difference spectrum over an 8-10 min period. These data suggest that a pH-dependent conformational relaxation process may influence the early stages of reoxidation.
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PMID:Covalent assembly of mouse immunoglobulin G subclasses in vitro: application of a theoretical model for interchain disulfide bond formation. 95 49

Translation of total polysomal RNA from sarcoma 180 ascites cells in a wheat germ cell-free system produces two major polypeptides, A and B, with molecular weights of 50,000 and 45,000, respectively. Fractionation on Millipore filters or on oligo(dT)-cellulose leads to retention of the mRNA specific for protein A in the poly(A)-containing fraction and to accumulation of the B mRNA in the unadsorbed poly(A)-deficient fraction. The mRNA for B sediments at approximately 18 S; it is released as a 50S ribonucleorprotein upon EDTA treatment of polysomes. Its translation is particularly sensitive to an inhibitor present in the polysomal RNA. The poly(A)-deficient mRNA for the 45,000 dalton polypeptide is also present in mouse myeloma MPC-11 cells, where it seems to be localized in membrane-bound polysomes.
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PMID:A major species of mammalian messenger RNA lacking a polyadenylate segment. 106 3

MPC-11 myeloma cells synthesizing IgG were labeled in vitro with 3H-uridine and the cell lysates, or purified polysomes treated with rabbit antiserum against the purified MPC-11 protein. The specificity of the immune precipitation was tested by rabbit anti-egg albumin and by precipitation of polysomes from "non-producer" myeloma and HeLa cells. The specific precipitation was 10 to 15% of the total cytoplasmic RNA for the IgG-producing clone of MPC-11 and about 2% for the non-producer clone or HeLa cells. Up to 20% of the total polysomal and ribosomal RNA were precipitated from the IgG producing clone. This value correlated with the IgG synthesis of these cells which is also about 20% of the total protein produced. The results suggest that myeloma cells produce a relatively large quantity of IgG due to the presence of a large amount of specific m-RNA molecules.
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PMID:Immune precipitation of immunoglobulin producing polysomes from mouse myeloma cells. 116 19

Nuclei of MPC 11 mouse myeloma cells contain several species of small RNAs related to those found in other mammalian cells. These include U1 RNA, about 190 nucleotides in length and U2 RNA, about 170 nucleotides long. The 5'-termini of 32P-labelled U1 and U2 RNAs have been investigated by a fingerprinting technique involving digestion with T2-ribonuclease. The RNAs were found to have modified 5'-terminal structures of the form m3G(5')ppp (5')AmpUmpAp for U1 RNA and m3G(5')ppp(5')AmpUmpCmpCp for U2 RNA, where m3G is N2, N27-trimethyl guanosine and Am and Um are 2'-O-methyl nucleosides. These 5'-terminal sequences are the same as those proposed for rat hepatoma U1 and U2 RNAs (Ro-Choi et al., Fed. Proc. 33, 1548, 1974) but with triphosphate rather than diphosphate links.
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PMID:Modified 5'-termini in small nuclear RNAs of mouse myeloma cells. 121 81

Long-term cultivation of anchorage-independent animal cells immobilized within porous biomass support particles (BSPs) using a gas-stirred circulating bed fermentor (CBF) was investigated. Inoculation of mouse myeloma MPC-11 (ATCC CCL 167) cells into reticulated polyvinyl formal resin BSPs (3 x 3 x 3 mm; mean pore diameter, 60 microns; porosity, 0.88) and the repeated batch culture of inoculated cells were performed under gentle circulation of BSPs, induced by sparging air from the base of the fermentor. The glucose uptake rate of cells decreased in the initial period just after the start of circulation, since a relatively large number of cells leaked from the BSPs. After that period, the uptake rate gradually increased and the leakage of cells diminished. In the meantime, when inoculated cells were incubated statically by introducing air into days before circulating the BSPs, glucose consumption became very rapid and cell density in the BSPs reached at least 10(7) cells/cm3 BSP. Thus, a long-term cultivation without significant leakage of cells and with high cell density in BSPs was successfully achieved in the CBF-BSP system.
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PMID:Long-term cultivation of anchorage-independent animal cells immobilized within reticulated biomass support particles in a circulating bed fermentor. 136 98

Growth and death of anchorage-independent animal cells entrapped within porous biomass support particles (BSPs) in static or shake-flask cultures were evaluated by comparison of enzyme activity with non-immobilized cells grown under static culture using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and release of lactate dehydrogenase into the culture medium. Mouse myeloma MPC-11 (ATCC CCL 167) cells inoculated within porous polyvinyl formal resin BSPs (3 x 3 x 3 or 2 x 2 x 2 mm; mean pore diameter, 60 microns) grew exponentially at a specific growth rate comparable to that of non-immobilized cells in the initial period of incubation. Entrapped cells then reached the stationary phase with a cell density over 10(7) cells/cm3 BSP. The death rate of entrapped cells increased in response to the rise in viable cell density in the BSPs. Observation of viable cell distribution within the BSPs using MTT staining indicated that the cells concentrated within a thin outer shell of the BSPs with time. After the immobilized cells reached the stationary phase, penetration of cells into the outer shell ceased and heterogeneous distribution of cell density occurred in the viable cell layer in the shake-flask culture.
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PMID:Growth and death behaviour of anchorage-independent animal cells immobilized within porous support matrices. 136 43

Differentiating B lymphocytes undergo changes in cell-cell and cell-matrix adhesion that control their movement through a series of distinct microenvironments. The integral membrane proteoglycan, syndecan, is a candidate for mediating B lymphocyte-matrix interactions because it is expressed on B lymphocytes only at times when they associate with matrix, and because syndecan is known to behave as a matrix receptor on simple epithelia. However, syndecan from B lymphocytes is significantly smaller in molecular mass than syndecan from simple epithelia (85 vs 160 kDa) suggesting that syndecan may have distinct functions on these two cell types. Our study was undertaken to determine if syndecan mediates adhesion of B lineage cells to extracellular matrix. The murine myeloma cell line MPC-11 was used because syndecan is the only major heparan sulfate proteoglycan detected on these cells and because they express a form of syndecan almost identical to that found on normal B lymphocytes. Cell binding assays demonstrate that syndecan binds MPC-11 cells to type I collagen. Binding is inhibited by heparin, by pretreatment of cells with heparitinase or by growth of cells before the assay in chlorate, an inhibitor of sulfation. Solid phase assays show that syndecan purified from MPC-11 cells binds to type I collagen but not type IV collagen, laminin, or fibronectin. The interaction of MPC-11-derived syndecan with type I collagen is of relatively high affinity (Kd app = 143 nM) as measured by affinity coelectrophoresis. However, the 160-kDa form of syndecan isolated from epithelial cells has a greater than fourfold higher affinity for type I collagen (Kd app = 31 nM) than does the MPC-11 syndecan, suggesting that different molecular forms of syndecan have distinct ligand binding properties. These results demonstrate that syndecan can mediate B lymphocyte interactions with matrix and suggest that changes in syndecan expression during B cell differentiation are a mechanism for controlling B cell localization within specific microenvironments.
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PMID:Adhesion of B lymphoid (MPC-11) cells to type I collagen is mediated by integral membrane proteoglycan, syndecan. 160 36


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