scholarly journals Absence of p53 Complements Defects in Abelson Murine Leukemia Virus Signaling

2003 ◽  
Vol 77 (11) ◽  
pp. 6208-6215 ◽  
Author(s):  
Indira Unnikrishnan ◽  
Naomi Rosenberg
Keyword(s):  
B Cells ◽  
Murine Leukemia Virus ◽  
Cellular Response ◽  
Leukemia Virus ◽  
Binding Pocket ◽  
Transformation Process ◽  
Sh2 Domain ◽  
Wild Type ◽  
Abelson Murine Leukemia Virus ◽  
Murine Leukemia

ABSTRACT The v-Abl protein encoded by Abelson murine leukemia virus (Ab-MLV) induces transformation of pre-B cells via a two-stage process. An initial proliferative phase during which cells with limited tumorigenic potential expand is followed by a crisis period marked by high levels of apoptosis and erratic growth. Transformants that survive this phase emerge as fully malignant cells and usually contain mutations that disable the p53 tumor suppressor pathway. Consistent with the importance of p53 in this process, pre-B cells from p53 null animals bypass crisis. Thus, the transformation process reflects a balance between signals from the v-Abl protein that drive transformation and those coming from the cellular response to inappropriate growth. One prediction of this hypothesis is that Ab-MLV mutants that are compromised in their ability to transform cells may be less equipped to overcome the effects of p53. To test this idea, we examined the ability of the P120/R273K mutant to transform pre-B cells from wild-type, p53 null, and Ink4a/Arf null mice. The SH2 domain of the v-Abl protein encoded by this mutant contains a substitution that affects the phosphotyrosine-binding pocket, and this mutant is compromised in its ability to transform NIH 3T3 and pre-B cells, especially at 39.5°C. Our data reveal that loss of p53 or Ink4a/Arf locus products complements the transforming defect of the P120/R273K mutant, but it does not completely restore wild-type function. These results indicate that one important transforming function of v-Abl proteins is overcoming the effects of a functional p53 pathway.

Differentiation of cloned populations of immature B cells after transformation with abelson murine leukemia virus

Cell ◽  
1983 ◽  
Vol 32 (3) ◽  
pp. 903-911 ◽  
Author(s):  
Cheryl A. Whitlock ◽  
Steven F. Ziegler ◽  
Lucy J. Treiman ◽  
Joy I. Stafford ◽  
Owen N. Witte
Keyword(s):  
B Cells ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Immature B Cells ◽  
Abelson Murine Leukemia Virus ◽  
Murine Leukemia

scholarly journals Changes in p19Arf Localization Accompany Apoptotic Crisis during Pre-B-Cell Transformation by Abelson Murine Leukemia Virus

2008 ◽  
Vol 82 (17) ◽  
pp. 8383-8391 ◽  
Author(s):  
Rebekah Stackpole Zimmerman ◽  
Naomi Rosenberg
Keyword(s):  
Murine Leukemia Virus ◽  
Cell Transformation ◽  
Leukemia Virus ◽  
Early Time ◽  
Transformation Process ◽  
Multistep Process ◽  
Infected Cells ◽  
Abelson Murine Leukemia Virus ◽  
Rare Cells ◽  
Murine Leukemia

ABSTRACT Transformation by Abelson murine leukemia virus (Ab-MLV) is a multistep process in which growth-stimulatory signals from the v-Abl oncoprotein and growth-suppressive signals from the p19Arf-p53 tumor suppressor pathway oppose each other and influence the outcome of infection. The process involves a proliferative phase during which highly viable primary transformants expand, followed by a period of marked apoptosis (called “crisis”) that is dependent on the presence of p19Arf and p53; rare cells that survive this phase emerge as fully transformed and malignant. To understand the way in which v-Abl expression affects p19Arf expression, we examined changes in expression of Arf during all stages of Ab-MLV transformation process. As is consistent with the ability of v-Abl to stimulate Myc, a transcription factor known to induce p19Arf, Myc and Arf are induced soon after infection and p19Arf is expressed. At these early time points, the infected cells remain highly viable. The onset of crisis is marked by an increase in p19Arf expression and a change in localization of the protein from the nucleoplasm to the nucleolus. These data together suggest that the localization and expression levels of p19Arf modulate the effects of the protein during oncogenesis and reveal that the p19Arf-mediated response is subject to multiple layers of regulation that influence its function during Ab-MLV-mediated transformation.

scholarly journals Active lambda and kappa antibody gene rearrangement in Abelson murine leukemia virus-transformed pre-B cell lines.

1987 ◽  
Vol 165 (6) ◽  
pp. 1655-1674 ◽  
Author(s):  
D M Persiani ◽  
J Durdik ◽  
E Selsing
Keyword(s):  
B Cells ◽  
Cell Lines ◽  
Murine Leukemia Virus ◽  
Gene Rearrangement ◽  
Leukemia Virus ◽  
Chain Gene ◽  
Gene Rearrangements ◽  
Gene Recombination ◽  
Abelson Murine Leukemia Virus ◽  
Murine Leukemia

The two Abelson murine leukemia virus (A-MuLV)-transformed cell lines, BM18-4 and ABC-1, undergo immunoglobulin L-chain gene recombination during passage in tissue culture. BM18-4 cells are capable of kappa gene recombination, whereas ABC-1 cells are capable of both kappa and lambda gene recombination. The expression of H chains is apparently not necessary for continuing L chain gene recombination in either of these cells, although H-chain expression may have been involved in the initiation of L-chain gene recombination. All ABC-1 cells that have lambda gene rearrangements also display recombined kappa alleles, supporting the hypothesis that kappa and lambda gene recombination are initiated in an ordered, developmentally regulated manner in maturing B cells. However, analyses of the ABC-1 line indicate that pre-B cells that have initiated lambda gene recombination do not terminate kappa gene rearrangement. The lambda gene recombinations that occur in the ABC-1 cell line indicate that the germline order of lambda gene segments is: 5' ... V lambda 2 ... J lambda 2C lambda 2-J lambda 4C lambda 4 ... V lambda 1 ... J lambda 3C lambda 3-J lambda 1C lambda 1 ... 3'. In addition, the frequencies of lambda 1, lambda 2, and lambda 3 gene recombinations among ABC-1 cells are quite different than the frequencies of B cells producing lambda 1, lambda 2, and lambda 3 L-chains in the mouse. RS DNA recombinations also occur in the BM18-4 and ABC-1 cell lines, supporting the notion that Ig gene recombinases are involved in RS rearrangement. Recombined RS segments are infrequent among BM 18-4 cells but common among ABC-1 cells, suggesting that RS recombinational events often occur in maturing pre-B cells just before initiation of lambda gene rearrangements. This developmental timing is consistent with the hypothesis that RS recombination may be involved in the initiation of lambda gene assembly.

scholarly journals Nonrandom cytogenetic changes accompany malignant progression in clonal lines abelson virus-infected lymphocytes

Blood ◽  
1994 ◽  
Vol 84 (12) ◽  
pp. 4301-4309 ◽  
Author(s):  
SS Clark ◽  
Y Liang ◽  
CK Reedstrom ◽  
SQ Wu
Keyword(s):  
Tumor Progression ◽  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Lymphoid Cells ◽  
Full Transformation ◽  
Cytogenetic Abnormalities ◽  
Cytogenetic Changes ◽  
Abelson Murine Leukemia Virus ◽  
Murine Leukemia ◽  
Over Time

Initially, lymphoid cells transformed by v-abl or BCR/ABL oncogenes are poorly oncogenic but progress to full transformation over time. Although expression of the oncogene is necessary to initiate and maintain transformation, other molecular mechanisms are thought to be required for full transformation. To determine whether tumor progression in ABL oncogene-transformed lymphoid cells has a genetic basis, we examined whether progression of the malignant phenotype of transformed clones correlates with particular cytogenetic abnormalities. A modified in vitro bone marrow transformation model was used to obtain clonal Abelson murine leukemia virus-transformed B lymphoid cells that were poorly oncogenic. Multiple subclones were then derived from each clone and maintained over a marrow-derived stromal cell line for several weeks. Over time, clonally related Abelson murine leukemia virus-transformed subclones progressed asynchronously to full transformation. The data show that tumor progression can occur in the absence of detectable cytogenetic changes but, more importantly, that certain cytogenetic abnormalities appear reproducibly in highly malignant subclones. Therefore, three independent subclones showed deletion in a common region of chromosome 13. Other highly malignant cells carried a common breakpoint in the X chromosome, and, finally, two subclones carried an additional chromosome 5. These results are consistent with the hypothesis that ABL oncogenes are sufficient for the initial transformation of cells but that additional genetic events can drive oncogenic progression. These observations further suggest that diverse genetic mechanisms may be able to drive tumor progression in cells transformed with ABL oncogenes.

scholarly journals Moloney Murine Leukemia Virus-Induced Preleukemic Thymic Atrophy and Enhanced Thymocyte Apoptosis Correlate with Disease Pathogenicity

1999 ◽  
Vol 73 (3) ◽  
pp. 2434-2441 ◽  
Author(s):  
Christine Bonzon ◽  
Hung Fan
Keyword(s):  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Annexin V ◽  
Moloney Murine Leukemia Virus ◽  
Wild Type ◽  
Thymic Atrophy ◽  
Thymocyte Apoptosis ◽  
Mink Cell ◽  
Nih Swiss ◽  
Murine Leukemia

ABSTRACT Moloney murine leukemia virus (M-MuLV) is a replication-competent, simple retrovirus that induces T-cell lymphoma with a mean latency of 3 to 4 months. During the preleukemic period (4 to 10 weeks postinoculation) a marked decrease in thymic size is apparent for M-MuLV-inoculated mice in comparison to age-matched uninoculated mice. We were interested in studying whether the thymic regression was due to an increased rate of thymocyte apoptosis in the thymi of M-MuLV-inoculated mice. Neonatal NIH/Swiss mice were inoculated subcutaneously (s.c.) with wild-type M-MuLV (approximately 105 XC PFU). Mice were sacrificed at 4 to 11 weeks postinoculation. Thymic single-cell suspensions were prepared and tested for apoptosis by two-parameter flow cytometry. Indications of apoptosis included changes in cell size and staining with 7-aminoactinomycin D or annexin V. The levels of thymocyte apoptosis were significantly higher in M-MuLV-inoculated mice than in uninoculated control animals, and the levels of apoptosis were correlated with thymic atrophy. To test the relevance of enhanced thymocyte apoptosis to leukemogenesis, mice were inoculated with the Mo+PyF101 enhancer variant of M-MuLV. When inoculated intraperitoneally, a route that results in wild-type M-MuLV leukemogenesis, mice displayed levels of enhanced thymocyte apoptosis comparable to those seen with wild-type M-MuLV. However, in mice inoculated s.c., a route that results in attenuated leukemogenesis, significantly lower levels of apoptosis were observed. This supported a role for higher levels of thymocyte apoptosis in M-MuLV leukemogenesis. To examine the possible role of mink cell focus-forming (MCF) recombinant virus in raising levels of thymocyte apoptosis, MCF-specific focal immunofluorescence assays were performed on thymocytes from preleukemic mice inoculated with M-MuLV and Mo+PyF101 M-MuLV. The results indicated that infection of thymocytes by MCF virus recombinants is not required for the increased level of apoptosis and thymic atrophy.

scholarly journals Cloning and analysis of reverse transcript P160 genomes of Abelson murine leukemia virus.

1983 ◽  
Vol 45 (3) ◽  
pp. 1195-1199 ◽  
Author(s):  
S A Latt ◽  
S P Goff ◽  
C J Tabin ◽  
M Paskind ◽  
J Y Wang ◽  
...  
Keyword(s):  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Abelson Murine Leukemia Virus ◽  
Reverse Transcript ◽  
Murine Leukemia
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