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Query: UNIPROT:P06889 (Mol)
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A novel stage in early B-lymphocyte differentiation has been identified in normal mouse bone marrow cells. Earlier work had demonstrated that bone marrow cells characterized by low levels of Thy-1 and lack of a panel of lineage markers (Thy-1lo Lin- cells) were highly enriched for pluripotent hematopoietic stem cells. In this paper, we present evidence that another bone marrow population, which expressed low levels of Thy-1 and coexpressed B220, a B-lineage-specific form of the leukocyte common antigen, contained early and potent precursors for B lymphocytes upon in vivo transfer to irradiated hosts. These Thy-1lo B220+ cells, comprising 1 to 2% of bone marrow cells, were enriched for large cells in the mitotic cycle; the population lacked significant pluripotent hematopoietic stem cell activity and myeloid-erythroid progenitors. Most strikingly, Thy-1lo B220+ cells represented a highly enriched population of bone marrow cells that could be targets of Abelson murine leukemia virus transformation. We propose that Thy-1lo B220+ bone marrow cells represent the earliest stage of committed lymphocyte progenitors, intermediate in differentiation between Thy-1lo Lin- pluripotent stem cells and, in the B lineage, Thy-1- B220+ pre-B cells.
Mol Cell Biol 1989 Jun
PMID:Identification of a novel bone marrow-derived B-cell progenitor population that coexpresses B220 and Thy-1 and is highly enriched for Abelson leukemia virus targets. 892 55

Three distinct Fc receptors for IgG, Fc gamma RI, Fc gamma RII and Fc gamma RIII are known to be associated with human myeloid cells. Using mAb specific for these receptors, and the hydridoma cells lines that produce these mAb, we have examined the ability of each of these receptors on different myeloid cells and cell lines to mediate killing of tumor and red cell targets. Hybridoma cells (HC) expressing anti-Fc gamma RI, Fc gamma RII or Fc gamma RIII upon their surface were used as model self-directed tumor targets. Chicken erythrocytes (CE) were used as another type of target cell and in this case effector cell cytotoxicity was mediated by heteroantibodies (HA) composed of Fab fragments of anti-Fc gamma R mAb covalently linked to Fab fragments of rabbit anti-CE antibodies. Monocytes, lymphocytes, polymorphonuclear cells (PMNs) and the myeloid cell lines U937, HL-60 and THP-1 were used as effector cells either in their native state or after activation with rIFN-gamma. Direct comparison of cytotoxicity by the same effector cell population against both tumor and erythroid targets has permitted definitive evaluation of the ability of the different Fc gamma R to promote cytolysis under two different conditions. Monocytes were able to utilize Fc gamma RI, Fc gamma RII and Fc gamma RIII in killing both CE and HC targets, and incubation with rIFN-gamma augmented their ability to kill CE, particularly through Fc gamma RI. Fc gamma RII and Fc gamma RIII mediated killing of CE by untreated neutrophils. rIFN-gamma induced PMNs to express Fc gamma RI and to mediate killing of CE through this receptor. Moreover, HC targets were not lyzed by untreated neutrophils, but rIFN-gamma activated neutrophils killed HC bearing surface anti-Fc gamma RI and anti-Fc gamma RII, but not anti-Fc gamma RIII. Myeloid cell lines HL-60 and U937 were unable to perform cytotoxicity without prior culture with rIFN-gamma, following which they killed CE through Fc gamma RI and Fc gamma RII, but were still incapable of HC lysis. THP-1, another myeloid cell line, was cytotoxic to CE through Fc gamma RI and Fc gamma RII without activation. Following rIFN-gamma treatment, cytotoxicity through these two Fc gamma R increased and was also mediated by Fc gamma RIII but these cells were still unable to kill HC.(ABSTRACT TRUNCATED AT 400 WORDS)
Mol Immunol 1989 Oct
PMID:The functional properties of Fc gamma RI, II and III on myeloid cells: a comparative study of killing of erythrocytes and tumor cells mediated through the different Fc receptors. 253 42

The human alpha-globin gene displays the unusual property of transcriptional promiscuity: that is, it functions in the absence of an enhancer when transfected into nonerythroid cell lines. It is also unusual in that its promoter region lies in a hypomethylated HpaII tiny fragment (HTF) island containing multiple copies of the consensus sequence for the SP1-binding site. We have investigated whether there is a relationship between these two observations. First, we investigated the mouse alpha-globin gene since it does not lie in an HTF island. We have demonstrated that it was not transcriptionally promiscuous. Second, we studied the transcriptional activity of the human alpha-globin gene in the absence of the GC-rich region containing putative SP1-binding sites and found a small (two- to threefold) but consistent positive effect of this region on transcriptional activity in both nonerythroid and erythroid cell lines. However, this effect did not account for the promiscuous nature of the human alpha-globin gene. We found that in a nonreplicating system, the human alpha-globin gene, like that of the mouse, required a simian virus 40 enhancer in order to be transcriptionally active in nonerythroid and erythroid cell lines. Since we only observed enhancer independence of the human alpha-globin gene in a high-copy-number replicating system, we suggest that competition for trans-acting factors could explain these results. Finally, our experiments with the erythroid cell line Putko suggest that there are no tissue-specific enhancers within 1 kilobase 5' of the human alpha-globin cap site or within the gene itself.
Mol Cell Biol 1989 Jan
PMID:Transcriptional promiscuity of the human alpha-globin gene. 253 19

Cells of the hemopoietic system arise by proliferation and differentiation of progenitor cells. This process begins with multipotential stem cells which can self-renew and also undergo progressive differentiation to progenitor cells committed to particular lineages, ultimately yielding mature blood cells (D. Metcalf and M. A. S. Moore, Haematopoietic Cells, 1971). Early commitment of lymphoid progenitors is generally believed to separate the lymphoid lineage from the myeloid and erythroid lineages, whose progenitors are separated late in differentiation (Metcalf and Moore, 1971). We recently developed a derivative of Moloney murine leukemia virus (M-MuLV) in which the enhancer sequences from simian virus 40 were substituted into the M-MuLV long terminal repeat. This recombinant virus (delta Mo + SV M-MuLV) induces pre-B and B lymphoid leukemia with long latency after inoculation of 2-day-old NIH Swiss mice (R. Hanecak, P. K. Pattengale, and H. Fan, J. Virol. 62:2427-2436, 1988). In this report, we describe the derivation of a permanent, virus-producing cell line with the phenotypic characteristics of mature macrophages from a B-cell-derived lymphoblastic lymphoma induced by delta Mo + SV M-MuLV. Comparison studies of immunoglobulin heavy-chain gene rearrangements and also delta Mo + SV M-MuLV proviral integration sites confirmed that the macrophage cell line was derived from the original B-lymphoblastic lymphoma. Moreover, inoculation of the macrophage cell line into animals resulted in histiocytic sarcomas of the macrophage type, thus reflecting stable conversion of B-lymphoid tumor cells to the macrophage phenotype. These results suggest a closer relationship between lymphoid and myeloid cells than previously believed.
Mol Cell Biol 1989 May
PMID:Differentiation in vitro of a leukemia virus-induced B-cell lymphoma into macrophages. 254 61

To examine the role of human beta-globin enhancers in tissue-specific and developmental regulation, a hybrid beta-globin-simian virus 40 gene was analyzed in transgenic mice. A beta-globin DNA fragment containing two previously defined enhancers stimulated transcription from the simian virus 40 promoter in a tissue- and stage-specific pattern similar to that of the normal beta-globin gene. These results help to define the functions of beta-globin regulatory elements and suggest an approach for targeted expression of heterologous genes in erythroid cells in vivo.
Mol Cell Biol 1989 Oct
PMID:Beta-globin enhancers target expression of a heterologous gene to erythroid tissues of transgenic mice. 255 96

We report the isolation and characterization of the mouse carbonic anhydrase I (CAI) gene. Direct RNA sequence analysis of the 5' nontranslated regions of CAI mRNA from mouse colon and mouse erythroleukemia cells demonstrated tissue specificity in the lengths and sequences of CAI transcripts. Analysis of several mouse CAI genomic clones showed that the transcripts arose from a single CAI gene with two tissue-specific promoters and eight exons. CAI transcripts in the colon were found to initiate just upstream of the erythroid exon 2 of the CAI gene region sequence. Erythroid transcripts originated from a novel promoter upstream of exon 1, which was located more than 10 but less than 250 kilobases upstream of exon 2. Erythroid exon 1 contained only a nontranslated sequence, which was spliced to exon 2 via a cryptic splice acceptor site located in the region that encoded the colon mRNA 5' nontranslated sequence. The remaining exon-intron junctions were conserved in comparison with those of the CAII and CAIII genes.
Mol Cell Biol 1989 Aug
PMID:The mouse carbonic anhydrase I gene contains two tissue-specific promoters. 257 23

We used micrococcal nuclease to separate murine erythroleukemia cell (MELC) chromatin into soluble and insoluble fractions which differ in gene content and chromatin structure. Genes that are not expressed in the erythroid lineage, such as the Ig alpha and albumin genes, distribute preferentially into the soluble rather than the insoluble fraction, and are organized into nucleosomes in both fractions. Both alpha 1- and beta maj-globin genes are enriched in the insoluble fraction and are organized into structures that are partially devoid of nucleosomes in uninduced MELC, when the genes are transcriptionally inactive. Following chemical induction of MELC and the onset of globin gene transcription, globin gene enrichment and nucleosome disruption in the insoluble chromatin fraction increase. Using seven DNA subclones that span the beta maj-globin gene we show that insolubility and nucleosome disruption are largely limited to DNA sequences lying within the transcribed domain. Non-transcribed, flanking sequences are soluble and organized into nucleosomes. In addition, the globin genes found in insoluble, non-nucleosomal chromatin contain previously engaged RNA polymerases which can elongate globin RNA chains in vitro in a pattern qualitatively and quantitatively similar to intact nuclei. These results are discussed in terms of a model for globin gene activation during erythropoeisis.
J Mol Biol 1985 Mar 05
PMID:Nucleosome disruption precedes transcription and is largely limited to the transcribed domain of globin genes in murine erythroleukemia cells. 258 37

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.
Mol Cell Biol 1989 Nov
PMID:Two chicken erythrocyte band 3 mRNAs are generated by alternative transcriptional initiation and differential RNA splicing. 260 17

The human gene coding for the principal factor of erythroid cells differentiation, erythropoietin, has been isolated from the genomic phage library using an oligonucleotide probe for the gene. The construction of series of plasmids carrying the erythropoietin gene under the control of various regulatory elements is reported. Efficiency of the erythropoietin gene expression was estimated by testing of the biologically active erythropoietin in conditioned media 48 h after transient transfection of COS 1 and CHO cell lines.
Mol Gen Mikrobiol Virusol 1989 Mar
PMID:[A study of the cloned human erythropoietin gene expression in mammalian cells in vitro]. 272 39

Herbimycin A is one of the benzenoid ansamycin antibiotics isolated from a culture of Streptomyces species (Omura, S., A. Nakagawa, and N. Sadakane. 1979. Tetrahedron Lett. 1979: 4323-4326). Recent studies have shown that the antibiotic not only inhibits the phosphorylation of p60src in Rous sarcoma virus- (RSV) infected cells, but also reverses the cellular phenotypes acquired by transfection with tyrosine kinase oncogenes (Uehara, Y., M. Hori, T. Takeuchi, and H. Umezawa. 1985. Jpn. J. Cancer Res. 76:672-675; Uehara, Y., M. Hori, T. Takeuchi, and H. Umezawa. 1986. Mol. Cell. Biol. 6: 2198-2206; Uehara, Y., Y. Murakami, S. Mizuno, and S. Kawai. 1988. Virology. 164: 294-298). These studies and other evidence indicate that the antibiotic inhibits a reaction(s) closely associated with the function of cellular tyrosine kinases. We have found that herbimycin A is an effective inducing agent capable of triggering differentiation in two typical mouse in vitro differentiation systems, which have been considered to be quite different in their mechanism of induction: endoderm differentiation of embryonal carcinoma (F9) cells and terminal erythroid differentiation of erythroleukemia (MEL) cells. The results suggest that there is a common step in the intracellular differentiation cascade which is, directly or indirectly, associated with phosphorylation at specific (tyrosine) residues of cellular proteins. The significance of this finding with respect to the molecular mechanism of in vitro differentiation is discussed.
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PMID:Induction of in vitro differentiation of mouse embryonal carcinoma (F9) and erythroleukemia (MEL) cells by herbimycin A, an inhibitor of protein phosphorylation. 274 53


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