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J D Engel

Publications and source records attributed to J D Engel.

At least 109 records · Page 6Linked to original sources
PubMed1990

Activity and tissue-specific expression of the transcription factor NF-E1 multigene family.

NF-E1, a DNA-binding protein that recognizes the general consensus motif WGATAR, is the first tissue-specific factor to be identified in erythroid cells. Using a probe from the murine GF-1 (NF-E1) cDNA clone, we isolated three homologous chicken cDNAs: One of these corresponds to an mRNA (NF-E1a) that is abundantly and exclusively expressed in erythroid cells; a second mRNA (NF-E1b) is also expressed in all developmental stages of erythroid cells but is additionally found in a limited subset of other chicken tissues; mRNA representative of a third gene (NF-E1c) is expressed only in definitive (adult) erythrocytes within the red cell lineage but is also abundantly expressed in T lymphocytes and brain. All NF-E1 proteins are highly conserved within the DNA-binding domain and bind to the consensus motif with similar affinities in vitro; they are also all stimulatory trans-acting factors in vivo. The factors differ quantitatively in their ability to trans-activate reporter genes in which the number and position of cognate binding sites is varied relative to the transcriptional initiation site. These data suggest that the NF-E1 consensus motif directs a broader and more complicated array of developmental transcriptional regulatory processes than has been assumed and that NF-E1c may play a unique regulatory role in the developing chicken brain and in T lymphocytes.

Amino Acid Sequence↗
PubMed1990

From noncompliance to collaboration in the treatment of schizophrenia.

Although effective treatment for schizophrenia is available, patients' compliance with treatment prescriptions is notoriously poor. The authors reframe compliance as a collaborative relationship in which both the patient and practitioner assume responsibility for producing a treatment regimen to which the patient can adhere. Barriers that prevent a partnership in treatment may be related primarily to treatment techniques, to characteristics of the patient and his family, to the patient-clinician relationship, or to the treatment delivery system. A comprehensive approach to addressing these sources of noncompliance includes specific skills that can be acquired by the patient, family members, and the practitioner.

Antipsychotic Agents↗
PubMed1989

The type I insulin-like growth factor receptor is a motility receptor in human melanoma cells.

Insulin-like growth factors I and II (IGF-I and II) and insulin are chemotactic agents for the human melanoma cell line A2058. As shown in this report, the motility receptor mediating this response is the heterodimeric type I IGF receptor. These three factors are able to compete with 125I-labeled IGF-I for binding to the cell surface with IC50 values equal to approximately 2 (IGF-I), approximately 150 (IGF-II), and approximately 300 nM (insulin). Cross-linking of 125I-IGF-I to the cell surface with disuccinimidyl suberate followed by analysis with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography reveals a 130-kDa protein (reduced) consistent with the alpha component of a type I receptor and a 38-kDa protein which does not bind insulin, and thus could be another IGF-I cell surface binding protein. The anti-IGF-I receptor monoclonal antibody (alpha IR-3) also competes with labeled IGF-I in binding experiments. In contrast, a control monoclonal antibody, matched to alpha IR-3 with respect to IgG subclass, has no significant effect on IGF-I binding. While alpha IR-3 inhibits the motility induced by IGF-I, IGF-II, and insulin, pertussis toxin (0.01-1.0 micrograms/ml) has no significant effect on the motility induced by the insulin-like growth factors or insulin on this cell line. Therefore, the type I IGF receptor appears to mediate a highly potent pertussis toxin-insensitive motility response to IGF-I, IGF-II, and insulin. In contrast, motility induced by the autocrine motility factor, a cytokine produced by the A2058 cells, is not affected by alpha IR-3 but is extremely sensitive to pertussis toxin. When mixtures of autocrine motility factor and IGF-I are employed to induce chemotaxis, the resulting motility is greater than that induced by either agent alone. These data indicate that motility in this melanoma cell line can be initiated through multiple receptors that stimulate the cells by separate transduction pathways. This capability to respond to multiple stimuli could enhance the metastatic potential.

Antibodies↗
PubMed1989

Expression of delta-aminolevulinate synthase in avian cells: separate genes encode erythroid-specific and nonspecific isozymes.

A controversy has existed in the literature for the past several years regarding the number of vertebrate genes encoding the mitochondrial protein that initiates the first step in heme biosynthesis, delta-aminolevulinate synthase [ALAS; succinyl-CoA: glycine C-succinyltransferase (decarboxylating), EC 2.3.1.37]. By analysis of chicken ALAS cDNA clones isolated from both liver and erythroid cells, we show that at least two separate genes encode ALAS mRNAs. These experiments show that (i) two different genes encode the ALAS isozymes found in erythroid and in liver tissues, and (ii) while the product of the erythroid gene (ALASE) is expressed exclusively in erythroid cells, the hepatic form of the enzyme is expressed ubiquitously, suggesting that this is the nonspecific form (ALASN) found in all chicken tissues.

5-Aminolevulinate Synthetase↗
PubMed1989

The beta-globin stage selector element factor is erythroid-specific promoter/enhancer binding protein NF-E4.

The analysis of transcriptional regulatory proteins is often hampered because such factors are present in cells in only sparing abundance. Although direct biochemical purification has been successfully applied to the analysis of many of these factors, such methods are labor intensive and expensive. We have developed an alternative strategy to identify and characterize such trans-acting factors and have used it to analyze the proteins that interact with the chicken adult beta-globin gene enhancer and promoter. The methodology involves (1) a sensitive 'reverse' radioimmunoassay used for the identification of antibodies to sequence-specific DNA-binding proteins, and (2) a monoclonal antibody-based DNase I footprint selection technique, which unambiguously identifies proteins responsible for particular footprints. Because this methodology relies on the isolation of antibodies to sequence-specific DNA-binding proteins, it should be of general utility in studying any trans-acting regulatory factor for which a specific DNA-binding sequence can be identified. In the present analysis, we report the identification of a 65-kD protein that is present only in mature definitive (adult) chicken erythroid cells. We show that this protein (termed NF-E4) binds to closely related sequences present in both the beta-globin promoter and enhancer. Biochemical analysis of extracts prepared from both nonerythroid and a variety of erythroid cell types suggests that NF-E4 is the trans-acting factor that confers definitive erythrocyte stage-specific transcriptional activation to the adult beta-globin gene.

Animals↗
PubMed1989

Two chicken erythrocyte band 3 mRNAs are generated by alternative transcriptional initiation and differential RNA splicing.

The erythrocyte anion transport protein (band 3) mediates two distinct cellular functions: it provides plasma membrane attachment sites for the erythroid cytoskeletal network, and it also functions as the anion transporter between the erythrocyte cytoplasm and extracellular milieu. We previously showed that two chicken band 3 polypeptides are encoded by two different mRNAs with different translation initiation sites. Here we show that these two band 3 mRNAs are transcribed from two separate promoters within a single gene. In addition, the two pre-mRNAs are differentially spliced, leading to fusion with coding exons used in common in the two mRNAs. The chicken erythrocyte band 3 gene is therefore the first example of a gene that has two promoters within a single locus which function equally efficiently in one cell type at the same developmental stage.

Animals↗
PubMed1989

Transcription of the chicken histone H5 gene is mediated by distinct tissue-specific elements within the promoter and the 3' enhancer.

Molecular genetic analysis of a number of vertebrate erythroid cell-specific genes has identified at least two types of cis-acting regulatory sequences which control the complex developmental pattern of gene expression during erythroid cell maturation. Tissue-specific cellular enhancers have been identified 3' to three erythroid cell-specific genes, and additional regulatory elements have been identified in the promoters of many erythroid genes. We show that the histone H5 enhancer, like the adult beta-globin enhancer, is involved in mediating the developmental induction of histone H5 mRNA as erythroid cells mature. We also describe the preliminary characterization of a tissue-specific regulatory element within the 5' region of the H5 locus and describe investigations of the interaction between this element and the histone H5 enhancer in mediating histone H5 regulation.

Animals↗
PubMed1988

Structure, turnover, and heme-mediated suppression of the level of mRNA encoding rat liver delta-aminolevulinate synthase.

lambda gt11 cDNA libraries were constructed with poly(A)+ RNA preparations from both porphyric chicken and rat livers. A cDNA which encodes chicken hepatic delta-aminolevulinate synthase was cloned by screening with an anti-chicken liver delta-aminolevulinate synthase antibody. Using this cDNA as a probe, cDNAs encoding the entire protein coding sequence of rat hepatic delta-aminolevulinate synthase were then cloned. The complete nucleotide sequences of the cDNAs have been determined. The result predicts that the rat hepatic pre-delta-aminolevulinate synthase comprises 642 amino acids. We measured the half-life of the hepatic delta-aminolevulinate synthase mRNA by RNA blot hybridization analysis using allylisopropylacetamide-induced porphyric rats as an experimental model and the rat cDNA as a hybridization probe. The half-life of the mRNA determined by the injection of alpha-amanitin is as short as 20 min. This value is significantly shorter than the estimated half-lives of most other mRNAs in the differentiated tissues of animals. The effect of hemin administration on the level of hepatic delta-amino-levulinate synthase mRNA was also examined. The half-disappearance time of the mRNA after the hemin administration was essentially the same as that determined by alpha-amanitin or actinomycin D, and no additive effect was observed between alpha-amanitin and hemin on the half-life determination. The results provide convincing evidence that heme inhibits the transcription of delta-aminolevulinate synthase mRNA.

5-Aminolevulinate Synthetase↗
PubMed1988

Developmental regulation of beta-globin gene switching.

A chicken erythroid cell-specific enhancer is located in the intergenic region between the adult beta- and embryonic epsilon-globin genes. In this paper we show that the beta-globin enhancer stimulates transcription of both genes. epsilon-Globin is, however, inappropriately regulated since it is expressed in both embryonic and adult red blood cells. Appropriate stage-specific regulation is observed for both genes when they are present on one plasmid. By analysis of deletion and substitution mutants, we conclude that beta-globin tissue- and developmental stage-specific regulation is mediated by interaction of the beta-globin enhancer with a positive regulatory element within the adult beta-globin promoter, the developmental stage selector element (SSE).

Animals↗
PubMed1988

v-erbA specifically suppresses transcription of the avian erythrocyte anion transporter (band 3) gene.

Previous work has established that the v-erbA oncogene inhibits the temperature-induced differentiation of chick erythroblasts transformed with temperature-sensitive oncogene mutants. Here we demonstrate that v-erbA in differentiating erythroblasts specifically arrests expression of the erythrocyte anion transporter (band 3) gene at the transcriptional level. The v-erbA-induced differentiation block can be overcome by inducing cells to differentiate at alkaline pH. Under these conditions, which possibly impair biological activity of v-erbA, the maturing cells now express the anion transporter gene at high levels. However, its transcription is specifically and rapidly suppressed if v-erbA activity is restored by culturing the cells at neutral pH. Similar but less pronounced inhibition of gene expression by v-erbA was observed for the delta-amino-levulinic acid synthase gene. Additional evidence obtained with an inhibitor of band 3 activity suggests that the v-erbA-induced inhibition of band 3 gene expression is at least partly responsible for the differentiation block caused by this oncogene.

5-Aminolevulinate Synthetase↗
PubMed1988

Temperature-sensitive v-sea transformed erythroblasts: a model system to study gene expression during erythroid differentiation.

The isolation and characterization of a temperature-sensitive mutant (ts1 S13) of the avian erythroblastosis virus, S13, is described. The temperature-sensitive lesion in ts1 S13 was identified as affecting the tyrosine kinase activity but not the plasma membrane localization of the ts1 S13 v-sea gene product. Erythroblasts transformed by ts1 S13 can be induced to synchronously differentiate into erythrocytes in an erythropoietin (EPO)-dependent fashion. Analysis of erythrocyte-specific gene expression in ts1 S13 erythroblasts reveals that the transformed, self-renewing erythroblasts obtained at permissive temperature already express all erythrocyte genes tested for, although at a low level. Upon differentiation induction, expression of erythrocyte-specific genes is not coordinately regulated but rather involves complex regulatory mechanisms that appear to be specific for the individual genes.

Alpharetrovirus↗
PubMed1988

Two different mRNAs are transcribed from a single genomic locus encoding the chicken erythrocyte anion transport proteins (band 3).

The chicken erythrocyte anion transport protein (band 3 of the erythrocyte cytoskeleton) is a central component taking part in two widely divergent functions of erythroid cells; it is a primary determinant of cytoskeletal architecture and responsible for electroneutral Cl-/HCO3- exchange across the plasma membrane. To analyze interesting aspects of the developmental regulation of this gene, we have cloned the cDNA and genomic counterparts of the erythroid-specific anion transport protein. We show that a single genetic locus for band 3 encodes two different erythroid cell-specific mRNAs, with different translational initiation sites, which predict polypeptides of sizes very close to those observed in vivo. In vitro translation and immune precipitation of synthetic mRNA derived from one putative fully encoding cDNA clone demonstrate that this clone gives rise to a protein which is identical in size and antigenicity to bona fide chicken erythroid band 3.

Amino Acid Sequence↗
PubMed1987

Mylohyoid herniation: gross and histologic evaluation with clinical correlation.

The purpose of this study was to further document the presence of a mass herniating inferiorly through the mylohyoid muscle into the submandibular area, to identify the mass histologically, and to discuss its importance in a differential diagnosis of masses in this area. A mass that perforated the mylohyoid muscle was found in 45 of the 100 cadavers studied. These 45 cadavers contained a total of 63 herniations. Of the 60 male cadavers, 26 (43.33%) showed herniation, and 19 (47.50%) of the 40 female cadavers showed herniation. Histologic evaluation of the 63 biopsy specimens revealed the following: 30 herniating masses (47.61%) were of the sublingual gland; 28 (44.44%) were of the submandibular gland; 4 (6.34%) were composed of pure adipose tissue, and 1 (1.58%) was a cholesteatoma. Inflammation was found in 46 (73.00%) of the biopsy specimens, consisting of sclerosing sialoadenitis in 30 specimens (47.61%) and a mild chronic inflammatory infiltrate in 16 specimens (25.39%).

Diagnosis, Differential↗
PubMed1987

Expression of cytoskeletal protein 4.1 during avian erythroid cellular maturation.

We have isolated a cDNA clone encoding part of protein 4.1, an integral component of the erythrocyte cytoskeleton. The recombinant was isolated by immunological screening of a chicken erythroid lambda gt11 cDNA library using a monoclonal antibody directed against protein 4.1. DNA blot analysis shows that the gene is present as a single copy per haploid chicken genome, while RNA blot analysis reveals the presence of a single mRNA of 7 kilobases in reticulocytes. Message of the same size (in reduced amounts) is also present in an erythroleukemic cell line transformed by avian erythroblastosis virus and is also present in vastly reduced quantities in nonerythroid hemopoietic cells. Immunoblotting and immunofluorescence experiments show that a subset of the chicken 4.1 variant proteins is preferentially expressed during in vitro differentiation of chicken erythroleukemic cells. These data indicate that the gene is both actively transcribed and translated during early erythroid cellular maturation.

Animals↗