scholarly journals Expression of the c-myc oncogene under control of an immunoglobulin enhancer in E mu-myc transgenic mice.

1987 ◽  
Vol 7 (4) ◽  
pp. 1436-1444 ◽  
Author(s):  
W S Alexander ◽  
J W Schrader ◽  
J M Adams

Transgenic mice bearing a cellular myc oncogene coupled to the immunoglobulin heavy-chain enhancer (E mu) exhibit perturbed B-lymphocyte development and succumb to B lymphoid tumors. To investigate how the enhancer has affected myc expression, we analyzed the structure and abundance of myc transcripts in tissues of prelymphomatous mice and in the lymphomas. Expression of the E mu-myc transgene appeared to be confined largely to B lymphoid cells, being dominant in bone marrow, spleen, and lymph nodes, with no detectable expression in T cells or other hematopoietic lineages examined. The myc transcripts initiated very predominantly at the normal myc promoters, although use of the more upstream myc promoter was accentuated and an enhancer-associated promoter may be used infrequently. The level of E mu-myc transcripts in the preneoplastic lymphoid tissues and in the E mu-myc tumors was not markedly higher than myc RNA levels in proliferating normal lymphocytes. Thus, enforced expression of structurally normal myc transcripts at only a modestly elevated level has profound biological consequences. The absence of detectable endogenous c-myc RNA in any tumor, or in preneoplastic bone marrow, supports a negative feedback model for normal c-myc regulation.

1987 ◽  
Vol 7 (4) ◽  
pp. 1436-1444
Author(s):  
W S Alexander ◽  
J W Schrader ◽  
J M Adams

Transgenic mice bearing a cellular myc oncogene coupled to the immunoglobulin heavy-chain enhancer (E mu) exhibit perturbed B-lymphocyte development and succumb to B lymphoid tumors. To investigate how the enhancer has affected myc expression, we analyzed the structure and abundance of myc transcripts in tissues of prelymphomatous mice and in the lymphomas. Expression of the E mu-myc transgene appeared to be confined largely to B lymphoid cells, being dominant in bone marrow, spleen, and lymph nodes, with no detectable expression in T cells or other hematopoietic lineages examined. The myc transcripts initiated very predominantly at the normal myc promoters, although use of the more upstream myc promoter was accentuated and an enhancer-associated promoter may be used infrequently. The level of E mu-myc transcripts in the preneoplastic lymphoid tissues and in the E mu-myc tumors was not markedly higher than myc RNA levels in proliferating normal lymphocytes. Thus, enforced expression of structurally normal myc transcripts at only a modestly elevated level has profound biological consequences. The absence of detectable endogenous c-myc RNA in any tumor, or in preneoplastic bone marrow, supports a negative feedback model for normal c-myc regulation.


Blood ◽  
1987 ◽  
Vol 70 (5) ◽  
pp. 1316-1324 ◽  
Author(s):  
MR Loken ◽  
VO Shah ◽  
KL Dattilio ◽  
CI Civin

Abstract A panel of B lymphoid-reactive monoclonal antibodies was used to analyze the phenotypic changes that accompany B lymphocyte development in normal human bone marrow. The B lymphoid cells were identified using light scattering and the expression of CD19 on a flow cytometer. Quantitative three-color immunofluorescence was then used to correlate other cell surface antigens on these cells identified as B lymphoid in normal marrow. CD10 and CD20 identified almost exclusive populations and provided a convenient means of discriminating between the less and more mature B lineage cells. The CD10+ cells could be further subdivided using CD34. The population of CD19+, CD10+, CD34+ cells comprised only 0.6% of marrow cells, but these contained the majority of terminal deoxynucleotidyl transferase (TdT+) cells. In the assessment of class II antigens, HLA-DR was expressed on all B lineage cells whereas HLA-DP preceded HLA-DQ in appearance during the developmental process. Among the later antigens expressed on B lineage cells, cell surface IgM, CD20, and HLA-DQ were expressed at essentially the same time. Cell surface CD10 was lost at the time when CD21 and CD22 were acquired on the cell surface. These data illustrate that multiparameter flow cytometry can be used to define a continuous progression of stages of B lymphocyte development based on cell surface antigen expression even though these cells represent a minor fraction of normal marrow cells.


Cell ◽  
1986 ◽  
Vol 47 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Wallace Y. Langdon ◽  
Alan W. Harris ◽  
Suzanne Cory ◽  
Jerry M. Adams

Blood ◽  
1987 ◽  
Vol 70 (5) ◽  
pp. 1316-1324 ◽  
Author(s):  
MR Loken ◽  
VO Shah ◽  
KL Dattilio ◽  
CI Civin

A panel of B lymphoid-reactive monoclonal antibodies was used to analyze the phenotypic changes that accompany B lymphocyte development in normal human bone marrow. The B lymphoid cells were identified using light scattering and the expression of CD19 on a flow cytometer. Quantitative three-color immunofluorescence was then used to correlate other cell surface antigens on these cells identified as B lymphoid in normal marrow. CD10 and CD20 identified almost exclusive populations and provided a convenient means of discriminating between the less and more mature B lineage cells. The CD10+ cells could be further subdivided using CD34. The population of CD19+, CD10+, CD34+ cells comprised only 0.6% of marrow cells, but these contained the majority of terminal deoxynucleotidyl transferase (TdT+) cells. In the assessment of class II antigens, HLA-DR was expressed on all B lineage cells whereas HLA-DP preceded HLA-DQ in appearance during the developmental process. Among the later antigens expressed on B lineage cells, cell surface IgM, CD20, and HLA-DQ were expressed at essentially the same time. Cell surface CD10 was lost at the time when CD21 and CD22 were acquired on the cell surface. These data illustrate that multiparameter flow cytometry can be used to define a continuous progression of stages of B lymphocyte development based on cell surface antigen expression even though these cells represent a minor fraction of normal marrow cells.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 919-919 ◽  
Author(s):  
Zhengqi Wang ◽  
Geqiang Li ◽  
Zizhen Kang ◽  
Silvia T Bunting ◽  
William Tse ◽  
...  

Abstract Abstract 919 Signal transducer and activator of transcription 5 (STAT5) is a critical regulator of normal and leukemic lympho-myeloid hematopoiesis through activation downstream of early-acting cytokines, their receptors, and janus kinases (JAKs). Despite upstream activating mutations driving JAK-STAT phosphorylation in precursor-B acute lymphoblastic leukemia (B-ALL), activated JAK-STAT is absent from the aggressive “double hit” lymphomas expressing myc and bcl-2. Using C57BL/6 background transgenic mouse models for myc and bcl-2, we set out to determine whether endogenous STAT5 functions in guarding against B-ALL induced by combined myc/bcl-2 or myc alone. We first determined whether constitutive expression of bcl-2 driven from the H2K promoter and Moloney murine leukemia virus enhancer in C57BL/6 background STAT5-deficient hematopoietic cells could bypass blocks in B-lymphocyte development. Transgenic H2K/bcl-2 expression in hypomorphic STAT5abDN/DN mice, which are leaky and still produce some mature B-lymphocytes, largely rescued peripheral B-lymphocyte survival to near normal levels but could only rescue about 10% of the multilineage hematopoietic stem cell (HSC) competitive repopulating defect. Complete deletion of the entire STAT5ab locus resulted in the expected severe block of B-cell development at the pre-pro-B-cell stage following transplantation of STAT5ab null/null fetal liver cells into irradiated wild type or common γC−/− recipients. Peripheral B-lymphocyte development could not be restored by transgenic bcl-2 alone in the absence of STAT5. However, transgenic myc driven from an immunoglobulin H chain enhancer (Emu/myc) combined with H2K/bcl-2 induced B-ALL peripheral counts as high as 1.1 × 105 B-cells/ul and reduced latency (a median survival of 44 days) compared to wild-type control (a median survival of 91 days) in either lethally-irradiated (P<0.001; N range from 8–14 mice/group) or sub-lethally-irradiated cohorts of fetal liver transplanted mice (P=0.007; N range 10–20 mice/group). B-ALL in mice with or without STAT5 was a mix of Pro-B and Pre-B ALL (IgM-CD43+B220+CD19+/−CD4+/−) and morphologically similar in the spleen and bone marrow. Multi-parameter flow cytometry analysis of bone marrow cells from STAT5ab null/null fetal liver transplanted mice (N=4) showed that deletion of STAT5 significantly reduced by 11.5-fold (P=0.004) the fraction of long-term repopulating HSC (CD150+CD48-) c-Kit+Lin-Sca-1+ (KLS). In an independent adult Mx1-Cre conditional knockout of STAT5 by pI:pC treatment, lymphomas induced by Myc alone were also accelerated (P=0.05; N range 14–15 mice/group) with STAT5 maintained deleted in sorted B-cells. These mice also had reduced CD150+CD48- KLS cells (5.6-fold; N=4; P=0.006). Interestingly, several phenotypes recently reported as associated with increased HSC cycling and lymphoid-biased differentiation were observed. The mean fluorescence intensity of slamf1 (CD150) was reduced 2.2-fold (P<0.001; N=4) in conditional knockout mice and the B-lymphoid biased CD48+CD150+ or CD48-CD150- KLS cells representing short-term HSC/multipotent progenitors were not significantly reduced. Microarray analyses of the KLS fraction provided evidence that STAT5 promotes HSC maintenance and myeloid potential (limiting lymphoid commitment, cycling) in the KLS compartment. The deletion of STAT5 reduced expression of HSC self-renewal and quiescence promoting genes and increased immunoglobulin and B-lymphoid transcripts. Combined with the pre-pro-B-cell block, loss of STAT5 promotes accumulation of B-lineage committed progenitors as potential ALL initiating cells. The effects of bcl-2 and myc hits on STAT5 null/null hematopoietic cells are currently being further characterized with respect to B-cell developmental blocks and molecular heterogeneity. B-ALL has a high relapse rate and is driven by clonally diverse tumor propagating populations. Our work may have important implications for ALL drug therapy. In conclusion, we demonstrate that STAT5, considered primarily as functioning like an oncogene in hematologic malignancies upon persistent activation, can play a tumor suppressor-like role in subsets of B-ALL. These data add to an emerging understanding that endogenous STAT5 can suppress some cancers and transcriptionally regulate several cell cycle inhibitors. Disclosures: No relevant conflicts of interest to declare.


1986 ◽  
Vol 6 (9) ◽  
pp. 3221-3231
Author(s):  
R C Schwartz ◽  
L W Stanton ◽  
S C Riley ◽  
K B Marcu ◽  
O N Witte

Murine bone marrow was either singly or doubly infected with retroviral vectors expressing v-myc (OK10) or v-Ha-ras. The infected bone marrow was cultured in a system that supports the long-term growth of B-lineage lymphoid cells. While the v-myc vector by itself had no apparent effect on lymphoid culture establishment and growth, infection with the v-Ha-ras vector or coinfection with both v-myc and v-Ha-ras vectors led to the appearance of growth-stimulated cell populations. Clonal pre-B-cell lines stably expressing v-Ha-ras alone or both v-myc and v-Ha-ras grew out of these cultures. In comparison with cell lines expressing v-Ha-ras alone, cell lines expressing both v-myc and v-Ha-ras grew to higher densities, had reduced dependence on a feeder layer for growth, and had a marked increase in ability to grow in soft-agar medium. The cell lines expressing both oncogenes were highly tumorigenic in syngeneic animals. These experiments show that the v-myc oncogene in synergy with v-Ha-ras can play a direct role in the in vitro transformation of murine B lymphoid cells.


Blood ◽  
1999 ◽  
Vol 94 (1) ◽  
pp. 275-282 ◽  
Author(s):  
Ramendra K. Kundu ◽  
Frank Sangiorgi ◽  
Lan-Ying Wu ◽  
Paul K. Pattengale ◽  
David R. Hinton ◽  
...  

The human immunodeficiency virus type 1 (HIV-1) Tat gene, a potent transactivator of viral and cellular genes, has been proposed as a key agent in the pathogenesis of acquired immune deficiency syndrome related disorders, including nonHodgkin’s lymphoma. In cultured cells, the HIV-1 Tat protein can induce the expression of the cytokines interleukin-6 (IL-6) and IL-10, which are known to induce proliferation and differentiation of lymphoid cells. Such alterations in cytokine expression, together with a secondary genetic event, are thought to ultimately lead to oncogenic transformation. To address the influence of Tat on lymphoid development in the context of the whole organism, we produced several transgenic mouse lines that express the Tat gene under the control of an actin promoter. We show here that this promoter directs expression to a variety of sites, including spleen, bone marrow, and lymph nodes. Approximately 25% to 30% of the Tat-transgenic population developed enlarged spleens within 1 year after birth. On histological examination, a significant number of spleens from Tat-transgenic mice exhibited malignant lymphoma of B-cell origin. IgG heavy chain rearrangement confirmed the clonal B-cell nature of these lymphoproliferations. In contrast, T-cell receptor genes exhibited a germline (unrearranged) structure. Reverse transcription polymerase chain reaction analysis of transgenic spleens revealed that mRNA encoding cytokines IL-6 and IL-10 was upregulated, suggesting a possible mechanism for the B-cell expansion in vivo.


Blood ◽  
1993 ◽  
Vol 82 (8) ◽  
pp. 2396-2405 ◽  
Author(s):  
I Moreau ◽  
V Duvert ◽  
C Caux ◽  
MC Galmiche ◽  
P Charbord ◽  
...  

Abstract Normal human bone marrow stromal cells (BMSC) were isolated from Dexter- type long-term cultures according to their capacity to adhere to plastic and to their lack of hematopoietic antigens. The BMSC displayed a homogeneous appearance and a myofibroblastic phenotype in culture. The stromal cells (SC) were shown to support the proliferation of purified CD34+ hematopoietic progenitors and permitted us to maintain myeloid cells for several weeks in culture. In addition, the BMSC induced the proliferation of purified CD10+ s mu- fetal BM B-cell precursors (BCP). The capacity of the BMSC to induce the proliferation of early myeloid cells was shared by several other human fibroblastic- like cell types. In contrast, the BMSC were far superior to other adherent cells for induction of BCP proliferation. This capacity was largely mediated by endogenously produced interleukin-7 (IL-7), because it could be inhibited by anti-IL-7 antibody. In line with this finding, addition of IL-7 considerably enhanced BCP proliferation in cocultures with skin fibroblasts or synoviocytes. Thus, production of IL-7 appears to be a critical parameter that determines the ability of fibroblastic- like cells to induce BCP proliferation. Taken together, our data show that normal human myofibroblastic BMSC induce the proliferation of both early myeloid and B-lymphoid cells in the absence of accessory hematopoietic cells. The present system should constitute a model to study interactions between native human BM myofibroblastic stroma and various hematopoietic cell subsets.


1978 ◽  
Vol 148 (5) ◽  
pp. 1251-1270 ◽  
Author(s):  
W C Yang ◽  
S C Miller ◽  
D G Osmond

Radioautographic DNA labeling and rosetting techniques were combined to study the development of surface IgM, Fc, and complement receptors (FcR, CR) on small lymphocyte populations in mouse bone marrow. [3H]thymidine was either infused continuously to label newly formed cells for periods up to 4 days, or injected daily, 21--35 days before use, to label a sample of long-lived cells. Bone marrow cells were incubated with sensitized sheep erythrocytes to detect surface IgM, FcR, and CR, respectively, and examined radioautographically after cytocentrifugation. During [3H]thymidine infusion, marrow small lymphocytes lacking surface markers were the first to show [3H]thymidine labeling. Most of these cells became labeled by 4 days (IgM--ve, 89%; FcR--ve, 92%; Cr--ve, 88%). Labeling of small lymphocytes bearing surface IgM, FcR, and Cr began after an initial lag and increased to high values by 4 days (IgM + ve, 73%; FcR + ve, 82%; CR + ve, 83%). Labeled IgM + ve small lymphocytes formed progressively larger rosettes as cell age increased. Some proliferating large lymphoid cells formed rosettes for IgM, FcR, and CR. Labeled long-lived small lymphocytes expressed surface IgM, FcR, and CR, the incidence of each receptor being uniformly high (38--43%) and the rosettes tending to be larger than those formed by newly formed lymphocytes. In double-surface marker studies, FcR and CR rosettes were formed by some IgM--ve small lymphocytes as well as IgM + ve cells in the marrow. After transfusion of marrow cells from donor mice infused with [3H]thymidine for 24 h, many labeled newly formed lymphocytes homed into the splenic red pulp of unlabeled syngeneic recipients. Subsequently, these cells showed a rapid increase in the incidence of rosettes for surface IgM, FcR, and CR, together with a progressive enlargement of each type of rosette. Although all the labeled small lymphocytes recovered from the spleen developed both surface IgM and FcR by 3 days, only approximately one-half developed CR. The results demonstrate that most of the small lymphocytes bearing FcR, CR, and surface IgM in mouse bone marrow are newly formed indigenous cells. Each receptor becomes detectable by rosetting soon after the small lymphocytes are first produced. The newly formed, marrow-derived small lymphocytes are able to continue their development of surface IgM, FcR, and CR after migrating into the spleen, consistent with a maturation of primary B lymphocytes. In addition, the data indicate the genesis in mouse marrow of a non-B lineage of lymphocytes (notably, IgM--ve FcR + ve cells.). A minority of small lymphocytes bearing IgM, FcR, and CR in mouse marrow are long-lived cells, presumptive recirculating immigrants, differing in receptor status from the newly formed cells. The results are discussed with regard to the heterogeneity of marrow lymphocytes and proposed models of primary B lymphocyte and null lymphocyte production.


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