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

Crystal structures of Fab antibody fragments determined by X-ray diffraction characteristically feature four-domain, beta-barrel arrangements. A human antibody Fc fragment has also been found to have four beta-barrel domains. The structures of a few intact antibodies have been solved: in two myeloma proteins, the flexible hinge regions that connect the Fc to the Fab segments were deleted so the molecules were non-functional, structurally restrained, T-shaped antibodies; a third antibody, Kol, had no hinge residues missing but the Fc region was sufficiently disordered that it was not possible to relate its disposition accurately with respect to the Fab components. Here we report the structure at 3.5 A resolution of an IgG2a antitumour monoclonal antibody which contains an intact hinge region and was solved in a triclinic crystal by molecular replacement using known Fc and Fab fragments. The antibody is asymmetric, reflecting its dynamic character. There are two local, apparently independent, dyads in the molecule. One relates the heavy chains in the Fc, the other relates the constant domains of the Fabs. The variable domains are not related by this 2-fold axis because of the different Fab elbow angles of 159 degrees and 143 degrees. The Fc has assumed an asymmetric, oblique orientation with respect to loosely tethered yet almost collinear Fabs. Our study enables the two antigen-binding segments as well as the Fc portion of a functional molecule to be visualized and illustrates the flexibility of these immune response proteins.
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PMID:The three-dimensional structure of an intact monoclonal antibody for canine lymphoma. 144 55

Although IL-2 receptor beta chain (IL-2R beta) expressed in various lymphoid cell lines binds IL-2 with an intermediate affinity, IL-2R beta expressed in fibroblasts is unable to bind IL-2, suggesting that IL-2R beta is on its own not sufficient for generating the intermediate-affinity receptor and that lymphoid-specific regulatory control may be operated to allow IL-2R beta to bind IL-2. In the present study, we observed that human IL-2R beta expressed in a mouse myeloma X63-Ag8.653 (X63) by cDNA transfection did not bind IL-2, while the same IL-2R beta expressed in an IL-6-dependent mouse B cell hybridoma F12-28, which was obtained by cell fusion between X63 and lipopolysaccharide (LPS)-induced lymphoblasts, bound IL-2 with the intermediate affinity. Interestingly, when the human IL-2R beta cDNA-transfected X63 clone, which by itself manifests no IL-2 binding, was fused with LPS-induced lymphoblasts, the resultant hybridomas manifested intermediate-affinity IL-2 binding. The IL-2 binding was specifically inhibited by addition of antihuman IL-2R beta mAb (Mik-beta 1) but not by mAb against mouse IL-2R subunits, indicating that human IL-2R beta was responsible for the IL-2 binding, i.e. non-functional human IL-2R beta in X63 was converted to competent IL-2R beta by complementation with a mouse spleen cell-derived factor(s) through the cell fusion. Cross-linking experiments with [125I]IL-2 revealed the presence of a 61 kDa protein other than IL-2R beta in cells expressing the intermediate-affinity IL-2R.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Reconstitution of the intermediate-affinity interleukin-2 receptor by cell fusion. 148 30

We analysed immunoglobulin (Ig) gene rearrangements in 28 patients with multiple myeloma by Southern hybridization method. We used 5 probes which cover C kappa and kappa de loci of Ig light chain kappa gene, and JH, 5'S mu and S gamma 3 loci of Ig heavy chain gene. In 11 out of 12 patients with kappa-producing myeloma, DNA rearrangements were observed using C kappa probe. Among them, kappa de region was rearranged in 7 patients and kept germline configuration in 4 patients. In all of 14 patients with lambda-producing myeloma, C kappa region was deleted and kappa de region was rearranged. 5'S mu-probe was very useful for detecting class switch recombination, and furthermore by using S gamma-probe together, S mu-S gamma joining could be detected. In all of 10 patients with gamma-producing myeloma, 5'S mu and S gamma-probes detected the rearranged band of the same size on at least 1 allele, which suggested the presence of S mu-S gamma joinings. In 8 of 10 patients with Bence-Jones myeloma, 5'S mu-probe detected rearranged bands and the presence of class switch recombinations were suggested as observed in other Ig secretory myelomas. In other 2 patients with Bence-Jones myeloma, non-functional class switch recombinations were detected. The results of this study indicated that genotypes corresponded well to phenotypes in multiple myeloma, and further analysis in other types of B cell malignancies will be interesting.
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PMID:[Rearrangement of immunoglobulin light chain and heavy chain constant region genes in multiple myeloma]. 154 11

The human lambda L chain Ig gene complex consists of multiple JC gene segments. A seventh human lambda C region gene segment, C lambda 7, was found 2.7 kb downstream of C lambda 6 in this gene complex. A J lambda gene segment, J lambda 7, was found 1.2 kb upstream of C lambda 7 and contains potentially functional nonamer and heptamer recombination sites, an RNA splice site and J coding region. C lambda 7 maintains an open reading frame and encodes a new lambda isotype. C lambda 7 encodes Kern+ and Oz- determinants, but does not encode any of the Kern+Oz- myeloma proteins published to date. Nevertheless, we present evidence that JC lambda 7 is transcribed in normal lymphocytes and is functional. In contrast, we present new data that the C lambda 6 gene segment, reported by others to encode the Kern+Oz- protein, is non-functional due to a 4-bp insertion in our cosmid clone. The 4-bp insertion was characterized further in 32 genomic DNA samples by producing a distinctive restriction fragment length and verified by the DNA sequences of the polymerase chain reaction products of two different cell lines. We discuss the possibility that the Kern+Oz- myeloma proteins do not define an isotype and are not encoded by JC lambda 7 nor other non-allelic genes, and we discuss the level of expression of JC lamba 7 as compared to that of JC lambda 2 and JC lambda 3.
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PMID:The human lambda L chain Ig locus. Recharacterization of JC lambda 6 and identification of a functional JC lambda 7. 190 86

The development of functional Fc receptors (FcR) during induced differentiation with the tumor promoter, phorbol myristate acetate (PMA), was studied in the murine tumor cell line, P388. PMA induced the appearance of FcR on the membranes of P388 cells as indicated by the binding of IgG-coated sheep red blood cells (IgG-SRBC). Concentrations of PMA as low as 1 ng/ml were sufficient to induce the expression of FcR as well as to inhibit cellular division and to induce adherence in the P388 tumor cell line; however, optimal FcR induction occurred at PMA concentrations of 10-100 ng/ml. Immunofluorescent analysis with heat-aggregated myeloma proteins indicated that PMA induced FcR which were capable of binding IgG2a and IgG2b immunoglobulins, but not IgG1. Adherence to a substratum was determined to be a second required signal for expression of FcR, since PMA induction of P388 tumor cells in teflon dishes failed to fully develop FcR and adherence of P388 cells to poly-L-lysine-coated culture dishes in the absence of PMA was insufficient for FcR expression. FcR which appeared after PMA induction were non-functional in the sense that membrane-bound IgG-SRBC were not ingested to any significant extent by the tumor cells. However, if FcR induction occurred in the presence conA-induced rat spleen cell culture supernatants, phagocytosis of membrane-bound erythrocytes occurred. These findings suggest that for the expression of FcR which are capable of particle internalization, at least three identifiable membrane-transmitted signals are required during differentiation.
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PMID:Induction of functional Fc receptors in P388 leukemia cells. Requirement for multiple differentiation signals. 397 48

Leader, variable (V) and joining (J) gene segments, and adjacent regions of two rearranged alleles of the same kappa-chain producing mouse myeloma, comprising approximately 3,200 base pairs, have been sequenced. Sequence comparisons are reported. V-J joining in one of the alleles leads to a reading frame with a stop codon within the J-gene segments. Allelic exclusion is apparently realized in this tumour through the formation of such a non-functional allele.
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PMID:Functional and non-functional joining in immunoglobulin light chain genes of a mouse myeloma. 677 11

We have studied a diverse group of lymphoproliferative disorders (acute lymphoblastic leukaemia (ALL), chronic lymphocytic leukaemia (CLL), non-Hodgkin lymphoma (NHL) and myeloma) to determine if V kappa gene use is random or disease-specific and whether somatic mutations (a late event in B-cell differentiation) can provide additional information on the type of B cell involved in the neoplastic clone. In this group of disorders V kappa gene selection is not random and some members of each V kappa family are preferentially rearranged. V kappa genes from the distal portion of the locus are seldom used, possibly because rearrangement of the proximal locus by deletion is more efficient than rearrangement of the distal locus by inversion. Although pseudogenes account for 46% of the V genes in the kappa locus none were ever rearranged, even in non-functional rearrangements of lambda-producing leukemias, suggesting the existence of a mechanism which down-regulates the rearrangement of pseudogenes. N regions were noted at the VJ junction in 20% of alleles (in six CLL, three NHL, two ALL and one myeloma) possibly the result of kappa-chain recombination during the early period of B-cell maturation in which TdT is expressed. Nucleotide addition or imprecise joining at the VJ junction, resulting in a shift in the reading frame, were the commonest causes of non-functional rearrangement. The occurrence of somatic mutation broadly correlated with the stage of B-cell maturation from which the different disorders are thought to arise. However, there was no strict association and somatic mutations were demonstrated in 'typical CLL' while V kappa genes were germline in some follicular lymphomas; these findings suggest either heterogeneity in the stage of B-cell maturation at which these disorders arise or some variability in the process of somatic mutation.
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PMID:Variable kappa gene rearrangement in lymphoproliferative disorders: an analysis of V kappa gene usage, VJ joining and somatic mutation. 803 5

Alterations in kappa light chain expression were demonstrated to originate from genomic changes in the L-V intron (L-IVS) which changed the splicing pattern of the kappa mRNA. In R15, a mutant of mouse myeloma W3129 which produces no kappa light chain, a 358 bp novel sequence element (R15ns) of unknown origin replaced 19 bases of wild-type L-IVS, both altering the normal splicing pattern and activating a cryptic polyadenylation site. Subclones of R15 which reverted to kappa light chain production contained genomic deletions of R15ns and/or the surrounding intron. These deletions led to partial or full restoration of wild type kappa mRNA levels due to further changes in the pattern of mRNA processing. Two cryptic splice acceptor sites and a polyadenylation signal exist in the L-IVS; a cryptic splice acceptor sequence also exists in V kappa. These cryptic sites can be activated by changing the genomic context. It is thus possible to influence light chain expression without altering either the exon sequences or the known regulatory elements. Alterations in splicing patterns also serve to produce kappa light chains with novel variable region sequences and thereby could contribute to antibody diversity. Surprisingly, in the cell line producing this novel kappa light chain, intact alpha heavy chains were secreted in the absence of an apparent association with light chain. These studies also demonstrate that it is not possible to distinguish functional from non-functional genes solely by sequence analysis and that genes can both be inactivated and activated by changes in intron sequences.
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PMID:Intron sequences determine the expression of kappa light chain genes. 830 81

MUM1/IRF4 is a myeloma-associated oncogene transcriptionally activated as a result of t(6;14)(p25,q32) chromosomal translocation and by virtue of its juxtaposition to the immunoglobulin heavy chain gene (IgH) locus. When this oncogene becomes non-functional, no activated B/T lymphocytes and Ig secreting plasma cells are observed, suggesting that MUM1/IRF4 is crucial for lymphoid development. Its expression was analyzed in both reactive lymphoid and lymphoma tissues by means of an immunohistochemical technique using specific goat antiserum against MUM1/IRF4. This analysis detected a 50 kDa MUM1 product whose localization was restricted to the nuclei of the lymphocytes. The MUM1+ cells in reactive lymph nodes were found to consist of plasma cells and a small fraction (approximately 7.9%) of B cells harboring CD20+CD38+, which were located in the light zone of the germinal center. MUM1 expression in peripheral blood B/T lymphocytes was upregulated by mitogenic stimuli, suggesting that MUM1 positivity represents the activated state of the B/T cells. In B cell non-Hodgkin's lymphoma (NHL), MUM1 expression was observed in 73.2% (30/41) of diffuse large B cell lymphoma (DLBCL), 20% (1/5) of marginal zone lymphoma (MZL) and 43% (3/7) of small lymphocytic lymphoma (SLL) cases, whereas it was not seen in any cases of mantle cell lymphoma (MCL) or follicle center lymphoma (FCL). Also, MUM1 was stained at high intensity in various types of T cell lymphomas including adult T cell leukemia/lymphoma (ATL/L) and anaplastic large cell lymphoma (ALCL) and in the majority of Hodgkin's diseases. Our results suggest that a major proportion of lymphomas comprise either physiologically or aberrantly activated neoplastic lymphocytes expressing the MUM1 protein.
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PMID:MUM1/IRF4 expression as a frequent event in mature lymphoid malignancies. 1072 Jan 41

The methylation status, mutation and expression of RASSF1A, and mutations of RAS and BRAF were studied in 52 patients with multiple myeloma (MM), one plasma cell leukaemia (PCL) patient and four MM-derived cell lines. Aberrant methylation of RASSF1A was found in nine of 32 MM patients and in one of four MM cell lines (U266), where the associated loss of transcription was reversible by demethylation treatment. RASSF1A transcription was further investigated on anti-CD138-sorted plasma cell-enriched bone marrow samples from 10 MM, one PCL and three reactive plasmacytosis patients. While the wild-type RASSF1A transcript was detected in all three reactive plasmacytosis and the PCL samples, we found no detectable wild-type transcripts in six of 10 MM samples studied. In two MM samples, only the non-functional variant transcript was detected, whereas the other four showed loss of transcription. In great contrast to western data, RAS mutations were identified in only four of 31 (13%) MM patients. While no RASSF1A or BRAF mutation (V599E) was detected in any of the primary MM studied (n = 21), the latter was found in the U266 cell line. Taken together, these data indicate that alterations of RAS signalling are critical in MM pathogenesis. In our current studies of Chinese MM patients, these alterations involved frequent RASSF1A inactivation (60%) as a result of transcriptional silencing or expression of a non-functional variant transcript.
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PMID:Alterations of RAS signalling in Chinese multiple myeloma patients: absent BRAF and rare RAS mutations, but frequent inactivation of RASSF1A by transcriptional silencing or expression of a non-functional variant transcript. 1461 67


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