Mutation analysis of H19 and NAP1L4 (hNAP2) candidate genes and IGF2 DMR2 in Beckwith-Wiedemann syndrome.
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Beckwith-Wiedemann Syndrome↗
Biomedical subjects
D Munroe
Publications and source records attributed to D Munroe.
Identification of glucagon-like peptide-2 (GLP-2)-activated signaling pathways in baby hamster kidney fibroblasts expressing the rat GLP-2 receptor.
Glucagon-like peptide-2 (GLP-2) promotes the expansion of the intestinal epithelium through stimulation of the GLP-2 receptor, a recently identified member of the glucagon-secretin G protein-coupled receptor superfamily. Although activation of G protein-coupled receptors may lead to stimulation of cell growth, the mechanisms transducing the GLP-2 signal to mitogenic proliferation remain unknown. We now report studies of GLP-2R signaling in baby hamster kidney (BHK) cells expressing a transfected rat GLP-2 receptor (BHK-GLP-2R cells). GLP-2, but not glucagon or GLP-1, increased the levels of cAMP and activated both cAMP-response element- and AP-1-dependent transcriptional activity in a dose-dependent manner. The activation of AP-1-luciferase activity was protein kinase A (PKA) -dependent and markedly diminished in the presence of a dominant negative inhibitor of PKA. Although GLP-2 stimulated the expression of c-fos, c-jun, junB, and zif268, and transiently increased p70 S6 kinase in quiescent BHK-GLP-2R cells, GLP-2 also inhibited extracellular signal-regulated kinase 1/2 and reduced serum-stimulated Elk-1 activity. Furthermore, no rise in intracellular calcium was observed following GLP-2 exposure in BHK-GLP-2R cells. Although GLP-2 stimulated both cAMP accumulation and cell proliferation, 8-bromo-cyclic AMP alone did not promote cell proliferation. These findings suggest that the GLP-2R may be coupled to activation of mitogenic signaling in heterologous cell types independent of PKA via as yet unidentified downstream mediators of GLP-2 action in vivo.
Animals↗
A growing family of receptor genes for lysophosphatidic acid (LPA) and other lysophospholipids (LPs).
A missing component in the experimental analysis of cell signaling by extracellular lysophospholipids such as lysophosphatidic acid (LPA) or sphingosine-1-phosphate (S1P) has been cloned receptors. Through studies on the developing brain, the first such receptor gene (referred to as vzg-1) was identified, representing a member of the G-protein coupled receptor (GPCR) super family (1). Here we review the neurobiological approach that led to both its cloning and identification as a receptor for LPA, along with related expression data. Summarized sequence and genomic structure analyses indicate that this first, functionally identified receptor is encoded by a member of a growing gene family that divides into at least two subgroups: genes most homologous to the high-affinity LPA receptor encoded by vzg-1, and those more homologous to an orphan receptor gene edg-1 that has recently been identified as a S1P receptor. A provisional nomenclature is proposed, based on published functional ligand actions, amino acid composition and genomic structure whereby the receptors encoded by these genes are referred to as lysophospholipid (LP) receptors, with subgroups distinguished by letter and number subscripts (e.g., LPA1 for Vzg-1, and LPB1 for Edg-1). Presented expression data support the recently published work indicating that members of the LPB1 subgroup are receptors for the structurally-related molecule, S1P. The availability of cloned LP receptors will enhance the analysis of the many documented LP effects, while their prominent expression in the nervous system indicates significant but as yet unknown roles in development, normal function, and neuropathology.
Base Sequence↗
A prospective randomized trial of four three-drug regimens in the treatment of disseminated Mycobacterium avium complex disease in AIDS patients: excess mortality associated with high-dose clarithromycin. Terry Beirn Community Programs for Clinical Research on AIDS.
The optimal regimen for treatment of Mycobacterium avium complex (MAC) disease has not been established. Eighty-five AIDS patients with disseminated MAC disease were randomized to receive a three-drug regimen of clarithromycin, rifabutin or clofazimine, and ethambutol. Two dosages of clarithromycin, 500 or 1,000 mg twice daily (b.i.d.), were compared. The Data and Safety Monitoring Board recommended discontinuation of the clarithromycin dosage comparison and continuation of the rifabutin vs. clofazimine comparison. After a mean follow-up of 4.5 months, 10 (22%) of 45 patients receiving clarithromycin at 500 mg b.i.d. had died (70 deaths per 100 person-years) compared with 17 (43%) of 40 patients receiving clarithromycin at 1,000 mg b.i.d. (158 deaths per 100 person-years) (relative risk, 2.43; 95% confidence interval, 1.11-5.34; P = .02). After 10.4 months, 20 (49%) of 41 patients receiving rifabutin had died (81 deaths per 100 person-years) compared with 23 (52%) of 44 patients receiving clofazimine (94 deaths per 100 person-years) (relative risk, 1.20; 95% confidence interval, 0.65-2.19; P = .56). Bacteriologic outcomes were similar among treatment groups. In treating MAC disease in AIDS patients, the maximum dose of clarithromycin should be 500 mg b.i.d.
AIDS-Related Opportunistic Infections↗
Molecular genetic characterisation of frontotemporal dementia on chromosome 3.
We have previously localized a locus causing familial nonspecific dementia to the centromeric region of chromosome 3 in a pedigree from the Jutland area of Denmark. This pedigree shows anticipation. Here we present further analysis of these anticipation data which are suggestive of trinucleotide repeat expansion involvement. We also outline our strategies to clone the mutant gene via its putative associated trinucleotide repeat sequence.
Adult↗
Meeting the challenge of unscheduled outpatient visits.
Cancer patients receive multimodal therapy and treatments on an ongoing basis in free-standing cancer centers, infusion centers, and oncology offices and at home. To serve those who require unscheduled evaluation for treatment effects, one hospital developed a program to receive those visits on an inpatient cancer unit.
Appointments and Schedules↗
Functional characterization of human nucleosome assembly protein-2 (NAP1L4) suggests a role as a histone chaperone.
Histones are thought to play a key role in regulating gene expression at the level of DNA packaging. Recent evidence suggests that transcriptional activation requires competition of transcription factors with histones for binding to regulatory regions and that there may be several mechanisms by which this is achieved. We have characterized a human nucleosome assembly protein, NAP-2, previously identified by positional cloning at 11p15.5, a region implicated in several disease processes including Wilms tumor (WT) etiology. The deduced amino acid sequence of NAP-2 indicates that it encodes a protein with a potential nuclear localization motif and two clusters of highly acidic residues. Functional analysis of recombinant NAP-2 protein purified from Escherichia coli demonstrates that this protein can interact with both core and linker histones. We demonstrate that recombinant NAP-2 can transfer histones onto naked DNA templates. Deletion mutagenesis of NAP-2 demonstrates that both NH3- and COOH-terminal domains are required for histone transfer activity. Subcellular localization studies of NAP-2 indicate that it can shuttle between the cytoplasm and the nucleus, suggesting a role as a histone chaperone. Given the potential role of the human NAP-2 gene (HGMW-approved symbol NAP1L4) in WT etiology, we have elucidated the exon/intron structure of this gene and have analyzed the mutational status of NAP-2 in sporadic WTs. Our results, coupled with tumor suppression assays in G401 WT cells, do not support a role for NAP-2 in the etiology of WT. A putative role for NAP-2 in regulating cellular differentiation is discussed.
Amino Acid Sequence↗
A professional practice model: two key components.
Professional practice models provide decentralized approaches to nursing practice. The components of such a model should include a primary nursing delivery system, decentralized decision making, salary compensation, self-scheduling and quality circles. This article describes two of the key components of the model--salaried compensation and self-scheduling--on a unit in one agency.
Decision Making, Organizational↗
Molecular characterization of a chromosome translocation breakpoint t(11;14)(p13;q11) from the cell line KOPT-K1.
Recurrent chromosome translocations involving 11p13 and 14q11 are found in 5-10% of cases of T-ALL. The gene involved in the translocation on chromosome 14 is the T cell antigen receptor alpha or delta. The putative oncogene on chromosome 11 is rhombotin 2 (RBTN2)/translocated in T cell gene 2 (ttg-2), a member of the LIM family of proteins. In this paper we characterize a cell line KOPT-K1 that has a t(11;14)(p13;q11). The breakpoint on chromosome 11 involves an Alu-rich region with the break occurring between two Alu sequences on chromosome 11. In addition, approximately 70 bases from the break on chromosome 11 is a tetranucleotide repeat. Whether either of these structures played a role in the translocation is not known. No heptamer or nonamer sequences, implicated in other rearrangements were found near the breakpoint. The breakpoint on chromosome 11 maps more centromeric than previous translocations of this region. Despite this the RBTN2 gene is highly expressed in KOPT-K1. This cell line will be useful for investigating the role of RBTN2 in leukemogenesis and the mechanism by which the translocation alters the expression of RBTN2.
Base Sequence↗
Single-strand conformational polymorphism (SSCP) mapping of the mouse genome: integration of the SSCP, microsatellite, and gene maps of mouse chromosome 1.
Interspersed repetitive sequence (IRS) PCR and repetitive element-to-bubble (IRS-bubble) PCR have been utilized to rapidly generate large numbers of mouse-specific, chromosome 1-enriched STSs from mouse-hamster somatic cell hybrids. Single-strand conformational polymorphism (SSCP) has been used to localize 39 new repetitive element-linked STSs to the mouse map: 22 to Chr 1, 10 to Chr. 15, 2 each to Chrs 12 and 14, and three to Chr 7. In addition, we have integrated the SSCP, single-strand length polymorphism, and restriction fragment length polymorphism maps of mouse Chr. 1, resulting in a high-density map of the chromosome, containing over 100 loci, all typed on a single interspecific backcross.
Animals↗
Tales of poly(A): a review.
Until recently, evidence to support a translational role for the 3'-poly(A) tract of eukaryotic mRNAs has been mostly indirect, including: a correlation between the adenylation status of individual mRNAs and their translatability in vivo or in vitro, the demonstration that exogenously added poly(A) is a potent competitive inhibitor of the translation of poly(A)+mRNA, but not poly(A)-mRNAs in vitro, and a correlation between the abundance and stability of poly(A)-binding proteins (PABPs) and the rate of translational initiation in vivo. However, more recent studies demonstrate directly that poly(A)+mRNAs can initiate translation more efficiently than poly(A)-mRNAs, and indicate that this effect is: (i) targeted to the formation of 80S initiation complexes, and (ii) likely to be mediated by the cytoplasmic PABP. We suggest that the 3'-poly(A) tail should be considered a translational enhancer which may stimulate translational initiation in much the same way that transcriptional enhancers are thought to stimulate transcriptional initiation.
Animals↗
mRNA poly(A) tail, a 3' enhancer of translational initiation.
To evaluate the hypothesis that the 3' poly(A) tract of mRNA plays a role in translational initiation, we constructed derivatives of pSP65 which direct the in vitro synthesis of mRNAs with different poly(A) tail lengths and compared, in reticulocyte extracts, the relative efficiencies with which such mRNAs were translated, degraded, recruited into polysomes, and assembled into messenger ribonucleoproteins or intermediates in the translational initiation pathway. Relative to mRNAs which were polyadenylated, we found that nonpolyadenylated [poly(A)-]mRNAs had a reduced translational capacity which was not due to an increase in their decay rates, but was attributable to a reduction in their efficiency of recruitment into polysomes. The defect in poly(A)- mRNAs affected a late step in translational initiation, was distinct from the phenotype associated with cap-deficient mRNAs, and resulted in a reduced ability to form 80S initiation complexes. Moreover, poly(A) added in trans inhibited translation from capped polyadenylated mRNAs but stimulated translation from capped poly(A)- mRNAs. We suggest that the presence of a 3' poly(A) tail may facilitate the binding of an initiation factor or ribosomal subunit at the mRNA 5' end.
Animals↗
Vasoactive intestinal polypeptide immunoreactivity in the spinal cord of the guinea pig. A mapping study.
The distribution of vasoactive intestinal polypeptide-immunoreactive (VIP-IR) neurons in the lower medulla oblongata and the spinal cord has been analyzed in guinea pigs. This study includes results obtained by colchicine treatment and transection experiments. In the spinal cord, numerous VIP-IR varicosities were observed in the substantia gelatinosa of the columna dorsalis; some were also found in the substantia intermedia and the columna anterior. The spinal VIP-IR nerve fibers were mainly of intraspinal origin and oriented segmentally. VIP-IR nuclei in the spinal cord extended dorsally into corresponding regions of the caudal medulla oblongata, namely from the substantia intermedia medialis and lateralis into the vagus-solitarius complex and from the nucleus spinalis lateralis into the area of the nucleus reticularis lateralis. Additional VIP-IR perikarya were observed in the pars caudalis of the nucleus spinalis nervi trigemini. The VIP-IR nuclei within the caudal medulla oblongata probably form a continuous system with those localized within the spinal cord. They may be involved functionally in the modulation of cardiovascular and respiratory regulation in the guinea pig.
Animals↗
Deletion of 5'-coding sequences of the cellular p53 gene in mouse erythroleukemia: a novel mechanism of oncogene regulation.
The p53 gene is rearranged in an erythroleukemic cell line (DP15-2) transformed by Friend retrovirus. Here, we characterize the mutation and identify a deletion of approximately equal to 3.0 kilobases that removes exon 2 coding sequences. The gene is expressed in DP15-2 cells and results in synthesis of a 44,000-dalton protein that is missing the N-terminal amino acid residues of p53. The truncated protein is unusually stable and accumulates to high levels intracellularly. Moreover, it appears to have undergone a change in conformation as revealed by epitope mapping studies. This study represents the first description of an altered p53 gene product arising by mutation during neoplastic progression and identifies a region in the p53 protein molecule that plays a role in determining p53 stability in vivo.
Animals↗
DNA strand scission and ADP-ribosyltransferase activity during murine erythroleukemia cell differentiation.
The accumulation of DNA strand breaks and activation of ADP-ribosyltransferase (ADPRT) have recently been associated with cellular differentiation. Murine erythroleukemia (MEL) cells undergo erythropoietic differentiation when exposed to dimethyl sulfoxide (Me2SO) and several studies have suggested that DNA strand scission induced by this agent is a prerequisite for expression of the differentiated phenotype. Me2SO induction of MEL cells has also been associated with increases in ADPRT activity in one study, but not in another. We have monitored the effects of Me2SO on DNA strand breaks in preformed and replicating MEL cell DNA. The results clearly demonstrate that DNA fragmentation is not detectable during Me2SO induction of MEL differentiation, even in the presence of 3-aminobenzamide, an inhibitor of ADPRT. Further, these results are consistent with an absence of detectable changes in both endogenous and total potential ADPRT activity during Me2SO-induced MEL differentiation. These findings would argue against Me2SO induction of DNA strand scission and ADPRT in MEL cells undergoing differentiation.
Animals↗
Effect of ara-A on differentiation and proliferation of HL-60 cells.
The HL-60 human leukemic promyelocytic cell line can be induced to mature into terminally differentiated cells using certain chemotherapeutic agents. We have recently demonstrated that two inhibitors of DNA synthesis, cytosine arabinoside (ara-C) and aphidicolin, can induce HL-60 differentiation with the appearance of monocytic markers. These pyrimidine antimetabolites may have affected DNA methylation patterns and resulted in altered gene expression, or the differentiated phenotype may have occurred by inhibition of DNA replication. Consequently, we have extended these studies by using the purine analog, adenine arabinoside (ara-A), which also acts as an inhibitor of DNA synthesis. The results demonstrate that ara-A also induces HL-60 non-specific esterase activity and enhances expression of myeloid cell surface antigens, MY-4 and MO-1. The induction of a differentiated phenotype by ara-A occurs after partial inhibition of DNA synthesis, a finding similar to that observed with ara-C and aphidicolin. These observations indicate that purine, as well as pyrimidine analog inhibitors of DNA polymerization can induce differentiation of HL-60 cells along a monocytic lineage. These findings may be relevant to recent clinical trials that have employed low doses of ara-C in an attempt to induce differentiation of malignant hematopoietic cells.
Antibodies, Monoclonal↗
Effects of 1-beta-D-arabinofuranosylcytosine incorporation on eukaryotic DNA template function.
1-beta-D-Arabinofuranosylcytosine (ara-C) incorporates into DNA, and the extent of this incorporation correlates significantly with inhibition of DNA synthesis. The incorporated ara-C residue provides a poor primer terminus for further chain elongation. There is a highly significant relationship between formation of (ara-C) DNA and loss of clonogenic survival. The present studies confirm that incorporation of ara-C into DNA, and not the competitive inhibition of DNA polymerase, is responsible for inducing lethal cellular events. The results also demonstrate that the incorporated ara-C residue is not excised from the DNA strand. Furthermore, the presistence of ara-C residues in DNA inhibits recovery of DNA synthesis following exposure to drug. The relative DNA chain-terminating effect of ara-C provides several mechanisms of action that explain internucleotide and chain terminus positioning of ara-C residues, reinitiation of previously replicated DNA segments, and DNA strand or chromosomal breaks. The precise mechanism of action is dependent upon dose scheduling of this drug.
Animals↗
Relationships among Ara-CTP pools, formation of (Ara-C)DNA, and cytotoxicity of human leukemic cells.
Cytosine arabinoside (Ara-C) is the most effective agent in the treatment of acute myelogenous leukemia. This agent incorporates in leukemic cell DNA, and the extent of this incorporation correlates with loss of clonogenic survival. The incorporated Ara-C residue behaves as a relative DNA chain terminator, and the extent of (Ara-C)DNA formation correlates with inhibition of DNA synthesis. The incorporation of Ara-C into DNA requires the formation of Ara-CTP, and previous measurements of this metabolite have also been correlated with cytotoxicity. Because it is clinically relevant to define biochemical parameters predictive of Ara-C cytotoxicity, the present studies were undertaken to determine the relationship among Ara-CTP pools, formation of (Ara-C)DNA, and loss of clonogenic survival. The results demonstrate that the incorporation of Ara-C into DNA is the single most powerful predictor of cell lethality. Furthermore, although there is a correlation between Ara-CTP pools or continuous cellular exposure to Ara-CTP and cell kill, these relationships are less significant than that obtained with formation of (Ara-C)DNA. The extent of Ara-C incorporation into DNA can be predicted by the product of the Ara-CTP level and time (T), thus supporting the concept that Ara-C incorporation is dependent on continuous exposure to the triphosphate metabolite. These findings support the formation of (Ara-C)DNA as a highly predictive parameter of lethal cellular events.
Arabinofuranosylcytosine Triphosphate↗