Biomedical subjects

R P Perry

Publications and source records attributed to R P Perry.

At least 55 records · Page 3Linked to original sources

PubMed1987

The role of the kappa enhancer and its binding factor NF-kappa B in the developmental regulation of kappa gene transcription.

We report here on a comparison of plasmacytoma cell lines that differ markedly in their ability to express kappa immunoglobulin genes introduced by transfection, but nevertheless express their endogenous kappa genes at comparable levels. The cell line that fails to express exogenous kappa genes is nonpermissive for kappa enhancer function, apparently because it lacks a specific kappa enhancer-binding nuclear factor (NF-kappa B). We show that this same nuclear factor is also lacking in pre-B cells and that treatment of these cells with bacterial lipopolysaccharide induces the appearance of NF-kappa B in nuclear extracts and concomitantly activates the kappa enhancer. These findings indicate that factor NF-kappa B controls kappa enhancer activity, and that this activity is only transiently required during B cell maturation.

Animals↗

PubMed1987

Three functional ribosomal protein genes are unlinked in mouse genome.

The mouse chromosomes bearing three functional ribosomal protein (rp) genes were identified by Southern blot analysis of DNA from a panel of mouse-hamster hybrid cell lines. Unique sequence intron probes were used to distinguish the functional rp genes from their multiple processed pseudogene counterparts. The genes specifying ribosomal proteins S16, L30, and L32 were found to be on chromosomes 7, 15, and 6, respectively. Since these functional rp genes are widely dispersed in the mouse genome, coordinate regulation of their transcriptional activity cannot be accomplished by a structural alteration of a single chromosomal region. Rather, it would have to involve interactions with sequences or structural motifs that are common to all three genes.

Animals↗

PubMed1987

Glucocorticoids selectively inhibit translation of ribosomal protein mRNAs in P1798 lymphosarcoma cells.

When P1798 murine lymphosarcoma cells are exposed to 10(-7) M dexamethasone, there is a dramatic inhibition of rRNA synthesis, which is completely reversible when the hormone is withdrawn. In the present experiments we examined whether dexamethasone treatment causes any alteration in the accumulation or utilization of mRNAs that encode ribosomal proteins (rp mRNAs). No effect on the accumulation of six different rp mRNAs was detected. However, the translation of five of six rp mRNAs was selectively inhibited in the presence of the hormone, as judged by a substantial decrease in ribosomal loading. Normal translation of rp mRNA was resumed within a few hours after hormone withdrawal. In untreated or fully recovered cells, the distribution of rp mRNAs between polyribosomes and free ribonucleoprotein is distinctly bimodal, suggesting that rp mRNAs are subject to a particular form of translational control in which they are either translationally inactive or fully loaded with ribosomes. A possible relationship between this mode of translational control and the selective suppression of rp mRNA translation by glucocorticoids is discussed.

Animals↗

PubMed1986

Rearrangement of antigen receptor genes is defective in mice with severe combined immune deficiency.

A process unique to lymphocyte differentiation is the rearrangement of genes encoding antigen-specific receptors on B and T cells. A mouse mutant (C.B-17scid) with severe combined immune deficiency, i.e., that lacks functional B and T cells, shows no evidence of such gene rearrangements. However, rearrangements were detected in Abelson murine leukemia virus-transformed bone marrow cells and in spontaneous thymic lymphomas from C.B-17scid mice. Most of these rearrangements were abnormal: approximately 80% of Igh rearrangements deleted the entire Jh region, and approximately 60% of TCR beta rearrangements deleted the entire J beta 2 region. The deletions appeared to result from faulty D-to-J recombination. No such abnormal rearrangements were detected in transformed tissues from control mice. The scid mutation may adversely affect the recombinase system catalyzing the assembly of antigen receptor genes in developing B and T lymphocytes.

Abelson murine leukemia virus↗

PubMed1986

Tandem kappa immunoglobulin promoters are equally active in the presence of the kappa enhancer: implications for models of enhancer function.

Transcription of immunoglobulin kappa genes is regulated by enhancer and promoter elements, both of which function in a tissue-specific fashion. We have studied the interaction of these elements by transfecting plasmacytoma cells with genes that have tandem kappa promoters located next to a single kappa enhancer and assaying these genes for transient or stable transcription. We find that the promoters located proximal and distal to the enhancer function identically whether they are separated by 440 bp or by 2.7 kb or whether they are located 1.7 or 7.7 kb away from the enhancer. Our results indicate that the immunoglobulin kappa enhancer does not operate as a bidirectional entry site for RNA polymerase or for other factors associated with the transcription complex. Rather, they suggest that the enhancer exerts its influence uniformly over large distances and independently of the presence of intervening promoters.

Animals↗

PubMed1986

Transcriptional and posttranscriptional control of immunoglobulin mRNA production during B lymphocyte development.

A variety of cell lines representing different maturation stages of the B lymphocyte were used to analyse developmental changes in the transcriptional pattern through the mu-delta locus and the relationship between mu mRNA accumulation and transcriptional activity. As anticipated from earlier studies, we observed that RNA polymerase loading in the region between the mu m cleavage/poly A addition site and the delta 1 exon is markedly decreased in IgM secreting cells compared to cells bearing surface IgM or surface IgM and IgD. In several IgM secreting hybridomas, transcriptional termination mainly occurred downstream of the first mu m exon. Thus, the predominance of mu s-terminated transcripts in these cells would appear to be principally determined by RNA processing events, most likely by more efficient cleavage at the mu s poly A site and/or less efficient splicing of the C mu and mu m exons. In two plasmacytoma lines, polymerase unloading between the mu s and mu m sites also contributed significantly to the high mu s mRNA phenotype. Our results further indicate that posttranscriptional regulation is largely responsible for the greatly increased accumulation of mu mRNA in the IgM secretors. Interestingly, the sterile-mu RNA components do not seem to be subject to this posttranscriptional regulation.

Animals↗

PubMed1986

Immune complex-induced enteropathy in the rat. I. Clinical and histological features.

Adult male Sprague-Dawley rats injected with preformed rat anti-bovine serum albumin antibody-bovine serum albumin complexes prepared in fivefold antigen excess, developed intestinal lesions consisting of annular bands of serosal hyperemia alternating with nonhyperemic bands, causing a striped appearance. Histologically, vascular congestion and mucosal edema were observed; more severe lesions were accompanied by hemorrhage, epithelial necrosis and sloughing, and modest polymorphonuclear leukocyte infiltration. The lesions developed rapidly and were accompanied by hemoconcentration. A correlation between the dose of immune complexes injected and the intensity and extent of intestinal lesions was noted. The pathogenetic mechanism of the lesions was not determined. The similarity of the lesions to those observed in systemic anaphylaxis in the rat and experimental and clinical shock was cited. The implications of immune complex-induced enteropathy for studies of immune complex clearance by the mononuclear phagocyte system were considered.

Animals↗

PubMed1986

Properties of a mouse ribosomal protein promoter.

The three mouse ribosomal protein genes that have been analyzed to date, although evolutionarily unrelated, exhibit some remarkably similar sequence features at their 5' ends, some of which are shared by other genes in the "housekeeping" category. In order to appreciate the significance of these features, we have examined the transient expression of the genes encoding ribosomal proteins L32 and S16, as well as that of a set of 5'-deletion mutants of the L32 gene, in transfected primate cells. Our results reveal two important characteristics of the elements that positively regulate L32 transcription: they do not extend more than 36 nucleotides upstream of the major transcriptional initiation site, and they are insensitive to the presence of cis-linked simian virus 40 enhancer elements. The relevance of these findings to the general design features of housekeeping gene promoters is discussed.

Animals↗

PubMed1986

Regulated production of mu m and mu s mRNA requires linkage of the poly(A) addition sites and is dependent on the length of the mu s-mu m intron.

mRNAs encoding the membrane-associated (mu m) and secreted (mu s) forms of mu heavy chain are derived from transcripts of the same immunoglobulin gene by differential RNA processing. To help elucidate the mechanism that regulates the production of these two mu mRNAs during the course of B-lymphoid maturation, we produced a series of specifically modified mu-chain genes and studied their expression when transfected into cells representing either early or late developmental stages. We have established that proper regulation depends on linkage of the mu s and mu m poly(A) addition sites and the length of the mu s-mu m intron. Deletion of an 800 to 900-nucleotide segment from the central region of this intron abolishes regulation; replacement of this segment with miscellaneous DNA sequences restores it. From these results we propose a model in which regulation is principally achieved by competition between cleavage/polyadenylylation of the mu s site and splicing of the C mu 4 and mu m exons.

Animals↗

PubMed1985

Inducible transcription of the unrearranged kappa constant region locus is a common feature of pre-B cells and does not require DNA or protein synthesis.

Transcription of unrearranged kappa constant region (kappa 0) loci is dramatically induced in pre-B cells transformed by the Abelson murine leukemia virus when the cells are exposed to bacterial lipopolysaccharide (LPS). Transcriptional activity, detected both by accumulation of the 8-kilobase kappa 0 RNA product and by nuclear run-on measurements, is evident within a few hours after exposure to LPS and continues to increase over a 24-hr period. During this time, transcription of rearranged mu heavy-chain loci remains at the basal constitutive level. In accord with previous studies of the B-cell lymphoma 70Z/3, this transcriptional activation is accompanied by the appearance of a DNase I-hypersensitive site in the kappa enhancer region but not by any detectable hypomethylation of the locus. Moreover, the present studies demonstrate that induction of kappa transcription can occur in the absence of DNA or protein synthesis. These results have led us to propose a model in which an external signal such as LPS or a functionally equivalent lymphokine may initiate kappa transcription in pre-B cells by modifying or overriding the activity of an enhancer-specific factor.

Abelson murine leukemia virus↗

PubMed1985

Characterization of the multigene family encoding the mouse S16 ribosomal protein: strategy for distinguishing an expressed gene from its processed pseudogene counterparts by an analysis of total genomic DNA.

Two genes from the family encoding mouse ribosomal protein S16 were cloned, sequenced, and analyzed. One gene was found to be a processed pseudogene, i.e., a nonfunctional gene presumably derived from an mRNA intermediate. The other S16 gene contained introns and had exonic sequences identical to those of a cloned S16 cDNA. The expression of this gene was demonstrated by Northern blot analysis of nuclear poly(A)+ RNA with cDNA and unique sequence intron probes. Each S16 intron contains a well-preserved remnant of the TACTAAC motif, which is ubiquitous in yeast introns and known to play a critical role in intron splicing. A sequence comparison with two other mouse ribosomal protein genes analyzed in our laboratory, L30 and L32, revealed common structural features which might be involved in the control and coordination of ribosomal protein gene expression. These include the lack of a canonical TATA box in the -20 to -30 region and a remarkably similar 12-nucleotide pyrimidine sequence (CTTCCYTYYTC) that spans the cap site and is flanked by C + G-rich sequences. The nature of the other members of the S16 family was evaluated by three types of experiment: a DNase I sensitivity analysis to measure the extent of chromatin condensation; an analysis of the thermal stability of cDNA-gene hybrids to estimate the extent of divergence of each gene sequence from that of the expressed gene; and a restriction fragment analysis which distinguishes intron-containing genes from intronless processed genes. The results of these analyses show that all genes except the expressed S16 gene are in a condensed chromatin configuration associated with transcriptional quiescence; that most of the genes within the S16 family have sequences greater than 7% divergent from the expressed S16 gene; and that at least 7 of the 10 S16 genes lack introns. We conclude that the ribosomal protein S16 multigene family contains one expressed intron-containing gene and nine inactive pseudogenes, most or all of which are of the processed type.

Animals↗

PubMed1985

Nonproductive kappa immunoglobulin genes: recombinational abnormalities and other lesions affecting transcription, RNA processing, turnover, and translation.

Six nonproductive kappa immunoglobulin genes (kappa- alleles) were cloned and sequenced. The structural abnormalities discerned from sequence analysis were correlated with functional lesions at the level of transcription, RNA processing, turnover, and translation. Four kappa- alleles, three containing V kappa genes and one not, are transcribed at normal or even greater than normal rates, the defects in these genes being expressed at various posttranscriptional levels. The other two kappa- alleles, both of which lacked V genes, exhibited greatly depressed yet clearly detectable transcriptional activity. These results are consistent with a hierarchical relationship between enhancer and promoter elements in which the enhancer establishes transcriptional competence at the kappa locus and the promoter (or pseudopromoter) determines the relative level of transcriptional activity. One of the structural abnormalities discovered in this study, a large deletion which removes the entire J kappa region, also provides new insight into the mechanism of VJ and VDJ recombination.

Alleles↗

PubMed1984

Lipopolysaccharide-induced transcription of the kappa immunoglobulin locus occurs on both alleles and is independent of methylation status.

The transcriptional activity of the kappa immunoglobulin genes in a B-cell lymphoma line, 7OZ/3 was measured before and after stimulation by lipopolysaccharide (LPS). Analyses of accumulated nuclear RNA components and of nascent transcripts showed that LPS induces transcription of both the productively rearranged (kappa+) and the unrearranged (kappa) allele in these cells. This pattern of transcriptional activation correlates well with the LPS induced appearance of a DNAase I hypersensitive site on both alleles in the vicinity of a putative enhancer element (Parslow and Granner, Nucl. Acids Res. 11, 4775, 1983). However, the transcriptional activation is not accompanied by detectable hypomethylation at Hha I and Hpa II sites which are normally undermethylated when kappa genes are constitutively expressed. These findings have enabled us to evaluate the relative importance of various structural parameters to the transcriptional competence of the kappa locus.

Alleles↗

PubMed1984

Feeding of antigen reduces antigen-binding activity and blunts the secondary response of actively immunized rats.

Enteric administration of soluble or particulate antigens to unprimed animals has been repeatedly demonstrated to blunt or abrogate the cellular and humoral immune response to parenteral immunization. We tested the effect of administering bovine serum albumin by gavage or in the drinking water on the serum antigen-binding activity of rats primed by previous immunization with bovine serum albumin and alum. In some animals, this treatment served initially to boost the systemic humoral response; prolonged treatment led to a reduction in antigen-binding activity at a faster rate than was observed in sham-fed controls. In all rats treated with enteric antigen, the booster response to a second parenteral immunization was reduced or absent. Example of the use of enteric antigen in treatment of patients are cited. On the basis of our findings in rats and those of other investigators who studied mice, as well as the results obtained in patients, it is suggested that further exploration of the enteric approach to treating actively immunized subjects appears warranted.

Administration, Oral↗

PubMed1984

Mode of regulation of immunoglobulin mu- and delta-chain expression varies during B-lymphocyte maturation.

The transcription, processing, and accumulation of mu and delta mRNA was studied in several cell lines representing different stages of B-lymphocyte maturation. Our results indicate that the relative content of mu and delta mRNA is the major determinant of the IgM versus IgM + IgD phenotype and that the production of delta mRNA is regulated at distinctly different levels of gene expression in early and later developmental stages. In B cell lymphomas typical of early stages, transcription extends over the entire 25 kb of the mu- delta locus and the relative content of mu and delta mRNA is determined at the level of mRNA processing. In contrast, in cells typical of mature IgM secretors, transcription is terminated abruptly between the mu and delta genes, precluding the production of delta mRNA. We propose a model that accounts for qualitative and quantitative changes in mu-delta expression in the developing B lymphocyte.

Animals↗

PubMed1984

The gene family encoding the mouse ribosomal protein L32 contains a uniquely expressed intron-containing gene and an unmutated processed gene.

The family of approximately 16 genes encoding the mouse ribosomal protein L32 has been characterized by an analysis of a representative set of genomic clones. Surprisingly, this family contains only a single expressed intron-containing gene. This gene, termed rpL32 , has been completely sequenced and found to possess certain novel features including the presence in two of its introns of a sequence with high homology to the 5' end of U1 snRNA and a 5' terminal region exceptionally rich in pyrimidines. Most of the other members of the L32 family appear to be processed genes, some of which are identical or very similar to the rpL32 gene, except for the lack of introns. One unmutated gene was found to be integrated 28 nucleotides downstream of a canonical TATA box. However, despite this feature, the gene does not seem to be expressed, as judged by its extent of methylation compared to the expressed rpL32 gene.

Amino Acid Sequence↗

PubMed1984

Characterization of the expressed gene and several processed pseudogenes for the mouse ribosomal protein L30 gene family.

Five cloned genes encoding the mouse ribosomal protein L30 were isolated from a recombinant DNA library and characterized by restriction mapping and nucleotide sequence analysis. Only one of these genes has introns and is expressed; the others are inactive processed pseudogenes. The expressed gene consists of five exons and four introns spanning 2,723 nucleotides. Transcripts of this gene are processed into the mature L30 mRNA by pathways that exhibit both constraints and flexibility with regard to the order of intron excision. The L30 mRNA which is 457 to 468 nucleotides in length excluding the polyadenylic acid tail, exhibits some microheterogeneity at its 3' end and encodes a basic protein of 115 amino acids. The 5' portion of the rpL30 gene has some novel features which are remarkably similar to the previously characterized mouse rpL32 gene. These include homologous sequences in the -60 to -340 region, the absence of a good TATA consensus sequence, and the presence of a palindromic pyrimidine sequence that spans the cap site.

Animals↗

PubMed1984

Gold induced encephalopathy: case report.

We describe a case with neurologic disease manifested as encephalopathy, generalized muscle fasciculations, and peripheral neuropathy occurring in a patient treated with therapeutic doses of gold for presumed rheumatoid arthritis. The illness remitted promptly during chelation therapy with dimercaprol (BAL). A review of the limited experience in the literature with the central nervous system toxicity of gold is given.

Arthritis, Rheumatoid↗