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J F Mushinski

Publications and source records attributed to J F Mushinski.

At least 127 records · Page 7Linked to original sources
PubMed1983

DNA rearrangement and altered RNA expression of the c-myb oncogene in mouse plasmacytoid lymphosarcomas.

Three types of tumors termed plasmacytomas (ABPC's), lymphosarcomas (ABLS's), and plasmacytoid lymphosarcomas (ABPL's) arise in BALB/c mice treated with pristane and Abelson murine leukemia virus (A-MuLV). While most ABPC's and BLS's contain integrated A-MuLV proviral genome and synthesize the v-abl RNA, most ABPL's do not. The ABPL tumors were examined for the expression of other oncogenes that may be associated with their transformed state, in the absence of transforming virus. These tumors expressed abundant c-myb RNA of unusually large size and showed DNA rearrangements of the c-myb locus.

Abelson murine leukemia virus↗
PubMed1983

The murine immunoglobulin alpha gene expresses multiple transcripts from a unique membrane exon.

Immunoglobulin heavy chains of each class exist in two forms, membrane (m) and secreted (s), which have different carboxy-terminal sequences encoded by different gene segments. We have sequenced the DNA spanning the coding region for the carboxy-terminal end of the alpha m chain in a BALB/c genomic clone and have examined alpha mRNA expression in transformed and normal B cells. Unlike the other murine heavy chain genes, which have two membrane exons (M1 and M2), the alpha gene has only one membrane exon (alpha M1). This unusual exon encodes a highly conserved transmembranal peptide plus flanking amino acids singular to IgA. The complexity of the alpha gene transcription is also unusual. Downstream of alpha M1, three AATAAA hexanucleotides are used to terminate as many as six distinct alpha membrane mRNAs. These appear to differ only in length and splicing pattern of their 3'-untranslated regions, and thus, encode the same alpha m protein. The alpha s protein is approximately 4000 daltons smaller than alpha m as judged by in vitro translation and is coded by a single 2.0-kb alpha s mRNA. We propose that the expression of alpha s and the multiple alpha m mRNAs is differentially controlled at the level of transcriptional termination.

Animals↗
PubMed1983

Tumor-specific tRNA modifications in mouse plasmacytomas and other tumors.

RPC-5 chromatography has been used to analyze the aa-tRNA populations found in normal organs and in various tumors in experimental animals. The most extensively studied animal systems have been mineral-oil-induced mouse plasmacytomas and carcinogen-induced rat hepatomas. Certain aa-tRNA species appear to be tumor-specific, e.g., rat hepatoma phenylalanyl-tRNA1 and plasmacytoma asparaginyl-tRNAs2-4. In addition, one of the tumor-specific peaks of asparaginyl-tRNA can be found in normal livers of animals bearing plasmacytomas at a distant site. Many other significant quantitative and qualitative differences among histologically similar plasmacytomas and between normal tissues and plasmacytomas were observed in the chromatographic patterns of isoaccepting aa-tRNAs for 11 of 20 amino acids. Some of the qualitative differences in chromatographic patterns could be correlated with the tumorous nature of the tissue using computer analysis. The program utilized cluster analysis to compare the RPC-5 patterns of aa-tRNAs from 11 plasmacytomas and two normal tissues for each of the 20 amino acids. The variations in these chromatographic profiles are though to be caused by varying degrees of incomplete synthesis of some of the normally modified nucleosides in tRNAs.

Amino Acid Sequence↗
PubMed1983

Alterations in post-transcriptional modification of the Y base in phenylalanine tRNA from tumor cells.

Various tumor cells contain chromatographically distinct isoacceptor tRNA species. To decide whether the tumor-specific species represent an expression of a separate tRNA gene or only an undermodified form of normal tRNAPhe, nucleotide sequences of tRNAPhe isolated from neuroblastoma and normal mouse liver were determined by postlabeling techniques. The results showed identical sequences except for the changes of post-transcriptional modifications in the anticodon loop. Normal mouse liver tRNAPhe contained Cm32, Gm34, and the hypermodified YOH next to the 3' end of the anticodon. On the contrary, tRNAPhe from neuroblastoma contained C32, G34, and, instead of YOH base m1G. A small proportion of tRNAPhe species contained an undermodified YOH base. For the examination of the conditions leading to the undermodified tRNAPhe, Vero cells derived from the kidney of African green monkey in culture were used. In these cells, deprivation of methionine or lysine resulted in changes in tRNAPhe modification similar to those in tumor cells. Ehrlich ascites tumor cells were examined to determine whether the presence of altered tRNAPhe species in various tumors is also the result of starvation of some nutritional factors. Results obtained with these cells showed that tRNAPhe species lacking the Y base disappeared in tumor-bearing mice after intraperitoneal injection with a mixture of amino acids and vitamins. Thus it is concluded that tumor-specific tRNAPhe species are the products of aberrant post-transcriptional modification, not the transcripts of different, normally repressed genes.

Animals↗
PubMed1983

Increased expression of myc-related oncogene mRNA characterizes most BALB/c plasmacytomas induced by pristane or Abelson murine leukemia virus.

RNA blots of poly(A)-containing RNA from normal livers and spleens and from a number of transplantable hematopoietic and lymphoid BALB/c tumors, including early and late generation plasmacytomas, were hybridized with probes for four onc genes. abl RNA was abundant only in those tumors producing Abelson virus, bas RNA was found in approximately equal amounts in normal tissues and plasmacytomas, and myb RNA was absent in normal liver and plasmacytomas. Normal liver and spleen RNA showed faint traces of myc hybridization, but myc RNA was increased in most plasmacytomas. In one plasmacytoma, TEPC 1165, a particularly abundant amount of myc RNA was found, principally as a 3.5-kilobase band. In the other plasmacytomas, bands of 2.4- or 1.8-kilobase myc RNA were found. Southern blots of DNA from tumors that contained 2.4-kilobase or larger myc RNA showed myc hybridization to an EcoRI fragment of about 21 kilobase pairs, similar to the myc band in normal DNA. EcoRI digests of DNA from two tumors that expressed myc RNA of 1.8 kilobases showed an additional smaller myc band, suggesting that the myc gene is rearranged in these plasmacytomas. The basis for increased myc gene transcription in plasmacytomas is not understood, but the evidence suggests that different mechanisms may be operating in different plasmacytomas. Apparently, neither myc gene amplification nor myc gene rearrangement is required for increased myc transcription.

Abelson murine leukemia virus↗
PubMed1982

Amplification of immunoglobulin lambda constant genes in populations of wild mice.

The lambda immunoglobulin light chain (Ig lambda) locus of BALB/c inbred mice consists of two variable region gene segments (V lambda)1-3, and four constant region gene segments (C lambda)1,2,4,5. Each C lambda gene segment is associated with a unique joining segment (J lambda)2,4-7, and they are organized in two paired units, J3C3-J1C1 and J2C2-J4C4 (refs 4, 8). Using cDNA probes specific for C lambda 1 and C lambda 2 (ref. 9) we have analysed the genomic organization of the C lambda gene segments in wild-derived and inbred strains of mice. Although Southern blots of the genomic DNA of inbred mice show a constant pattern of hybridization, wild-derived mice show a high degree of variation in the number, size and intensity of hybridizing fragments. We have now found that, per haploid genome, mice of a Mus musculus musculus stock isolated from Sladeckovce, Czechoslovakia (CzII) have at least 12 C lambda segments, and mice of a Mus musculus domesticus stock 'Centreville Lights' from Centreville, Maryland (CL) have at least 8 C lambda segments. There appears to have been relatively recent amplifications of the C lambda gene segments in wild mice.

Animals↗
PubMed1982

Changes of post-transcriptional modification of wye base in tumor-specific tRNAPhe.

Nucleotide sequences of normal mouse liver tRNAPhe and tumor-specific tRNAPhes isolated from Ehrlich ascites tumor and neuroblastoma cells were examined by post-labeling techniques. The results showed that their sequences are identical, except for changes in post-transcriptional modifications that are located in the anticodon region. Normal mouse liver tRNAPhe contained Cm32, Gm34 and YOH37. On the other hand, tumor-specific tRNAPhes were found in one of two possible configurations: 1) Cm32, Gm34 and Y*OH37 (under-modified YOH) or 2) C32, G34 and m1G37. The ratio of the two forms of tRNAPhes differed in different tumor cells; Ehrlich ascites tumor tRNAPhe had mainly Y*OH-containing tRNAPhe whereas neuroblastoma tRNAPhe has predominantly m1G-containing tRNAPhe. It was concluded that tumor-specific tRNAPhes are products of different extents of modification, rather than of new tRNA transcription.

Animals↗
PubMed1981

Comparison of the codon recognition properties and of the utilization of normal and tumor specific Phe-tRNAs in protein synthesis.

Phe-tRNA from normal rat liver (designated Phe-tRNAN) and the under-modified, tumor specific, Phe-tRNAs from mouse neuroblastoma (designated Phe-tRNANB) and rat lymphoma (designated Phe-tRNARL) recognize the phenylalanine codons, UUU and UUC in a ribosome binding assay, but not other codons that differ from UUU and UUC in a single base at either the 5' or 3' position. Phe-tRNANB was incorporated into protein more extensively than either Phe-tRNARL or Phe-tRNAN in wheat germ extracts programmed with globin mRNA. The utilization level of each Phe-tRNA was correlated with its rate of deacylation in wheat germ extracts, i.e., Phe-tRNANB deacylated less rapidly than Phe-tRNARL or Phe-tRNAN. Phe-tRNA, from which the Y base was chemically excised (designated Phe-tRNA-Y), did not respond to UUU or UUC in the ribosomal binding assay, nor did it transfer its phenylalanine to protein in wheat germ extracts programmed with globin mRNA.

Animals↗
PubMed1981

IgD-secreting murine plasmacytomas: identification and partial characterization of two IgD myeloma proteins.

We have used an immunofluorescence inhibition assay to identify 2 BALB/c plasmacytomas, TEPC-1017 and TEPC-1033, that secrete large quantitites of IgD. Both TEPC-1017 and TEPC-1033 myeloma proteins bound to anti-kappa as well as hybridoma and heterologous anti-delta antibodies, but not to anti-mu, gamma, alpha, or lambda antibodies. Both myeloma proteins were purified by (NH4)2SO4 precipitation, ion exchange chromatography, gel filtration, and Staphylococcus aureus Protein A absorption. These IgD kappa myeloma proteins were used to prepare affinity purified rabbit antibodies to delta-chain and the TEPC-1017 and TEPC-1033 idiotypes. Native TEPC-1017 and TEPC-1033 both had mobilities between those of mouse IgA kappa dimers and trimers when analyzed by polyacrylamide gradient gel electrophoresis. Both IgD myeloma proteins broke down under mild reducing conditions into subunits with electrophoretic mobilities slightly slower than those of an IgA kappa monomer. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of reduced TEPC-1017 and TEPC-1033 demonstrated kappa-chains and heavy chains that co-migrated with alpha chain. These data suggested that secreted IgD contains 2 delta 2 kappa 2 subunits that are linked by an easily reducible disulfide bond. The kappa-chains of IgD secreted by TEPC-1017 and TEPC-1033 have apparent m.w. of approximately 63,000 daltons, whereas the apparent m.w. of intracytoplasmic delta-chain, intracytoplasmic delta-chain synthesized in the presence of tunicamycin, and the cellfree translation product of TEPC-1017 delta-chain mRNA are 54,000, 43,000, and 44,000 daltons, respectively. This is compatible with the interpretation that the delta-chain peptide has a leader sequence and is N-glycosylated during or shortly after peptide synthesis and is glycosylated further shortly before IgD secretion.

Animals↗
PubMed1980

Mapping of heavy chain genes for mouse immunoglobulins M and D.

A single DNA fragment containing both mu and delta immunoglobulin heavy chain genes has been cloned from normal BALB/c mouse liver DNA with a new lambda phage vector Charon 28. The physical distance between the membrane terminal exon of mu and the first domain of delta is 2466 base pairs, with delta on the 3' side of mu. A single transcript could contain a variable region and both mu and delta constant regions. The dual expression of immunoglobulins M and D on spleen B cells may be due to alternate splicing of this transcript.

Animals↗
PubMed1980

Mouse immunoglobulin D: messenger RNA and genomic DNA sequences.

The molecular structure of a mouse immunoglobulin D from a plasmacytoma tumor and that of the normal mouse gene coding for immunoglobulin D are presented. The DNA sequence results indicate an unusual structure for the tumor delta chain in two respects: (i) Only two constant (C) region domains, termed C delta 1 and C delta 3 by homology considerations, are found; the two domains are separated by an unusual hinge region C delta H that lacks cysteine residues and thus cannot provide the covalent cross-links between heavy chains typically seen in immunoglobulins. The two domains and hinge are all coded on separate exons. (ii) At the carboxyl end of the delta chain there is a stretch of 26 amino acids that is coded from an exon located 2750 to 4600 base pairs downstream from the rest of the gene. Analogy with immunoglobulin M suggests that this distally coded segment C delta DC may have a membrane-binding function; however, it is only moderately hydrophobic. A fifth potential exon (C delta AC), located adjacent to the 3' (carboxyl) end of C delta 3, could code for a stretch of 49 amino acids. The tumor's expression of the delta gene may be aberrant, but the simplest interpretation would be that this tumor expresses one of the several biologically significant forms of the delta chain.

Amino Acid Sequence↗