scholarly journals Disruption of the Shc/Grb2 Complex during Abelson Virus Transformation Affects Proliferation, but Not Apoptosis

2005 ◽  
Vol 79 (4) ◽  
pp. 2325-2334 ◽  
Author(s):  
Linda B. Baughn ◽  
Naomi Rosenberg
Keyword(s):  
B Cell ◽  
Protein Tyrosine Kinase ◽  
Cell Transformation ◽  
Leukemia Virus ◽  
Sh2 Domain ◽  
Dominant Negative ◽  
Growth And Survival ◽  
Erk Phosphorylation ◽  
Ras Activation ◽  
Abelson Virus

ABSTRACT The v-Abl protein tyrosine kinase encoded by Abelson murine leukemia virus (Ab-MLV) induces pre-B-cell transformation. Signals emanating from the SH2 domain of the protein are required for transformation, and several proteins bind this region of v-Abl. One such protein is the adaptor molecule Shc, a protein that complexes with Grb2/Sos and facilitates Ras activation, an event associated with Ab-MLV transformation. To test the role this interaction plays in growth and survival of infected pre-B cells, dominant-negative (DN) Shc proteins were coexpressed with v-Abl and transformation was examined. Expression of DN Shc reduced Ab-MLV pre-B-cell transformation and decreased the ability of v-Abl to stimulate Ras activation and Erk phosphorylation in a Raf-dependent but Rac-independent fashion. Further analysis revealed that Shc is required for v-Abl-mediated Raf tyrosine 340 and 341 phosphorylation, an event associated with Erk phosphorylation. In contrast to effects on proliferation, survival of the cells and activation of Akt were not affected by expression of DN Shc. Together, these data reveal that v-Abl-Shc interactions are a critical part of the growth stimulatory signals delivered during transformation but that they do not affect antiapoptotic pathways. Furthermore, these data highlight a novel role for Shc in signaling from v-Abl to Raf.

scholarly journals The effect of helper virus on Abelson virus-induced transformation of lymphoid cells.

1978 ◽  
Vol 147 (4) ◽  
pp. 1126-1141 ◽  
Author(s):  
N Rosenberg ◽  
D Baltimore
Keyword(s):  
Bone Marrow Cells ◽  
Cell Transformation ◽  
Leukemia Virus ◽  
Fibroblast Cell ◽  
Helper Virus ◽  
Lymphoid Cells ◽  
Mouse Bone Marrow ◽  
Abelson Virus

Abelson murine leukemia virus (A-MuLV)-transformed fibroblast nonproducer cells were used to prepare A-MuLV stocks containing a number of different helper viruses. The oncogenicity of the A-MuLV stocks was tested by animal inoculation and their ability to transform normal mouse bone marrow cells was measured in vitro. All of the A-MuLV stocks transformed fibroblast cells efficiently. However, only A-MuLV stocks prepared with helper viruses that are highly oncogenic were efficient in vivo and in vitro in hematopoietic cell transformation. In addition, inefficient helpers did not establish a stable infection in lymphoid nonproducer cells. Thus, helper virus has a more central role in lymphoid cell transformation than in fibroblast cell transformation.

Ras signaling in the inner medullary cell response to urea and NaCl

2000 ◽  
Vol 278 (2) ◽  
pp. C372-C380 ◽  
Author(s):  
Wei Tian ◽  
Gerry R. Boss ◽  
David M. Cohen
Keyword(s):  
Cell Response ◽  
Collecting Duct ◽  
Statistical Significance ◽  
Dominant Negative ◽  
Luciferase Reporter ◽  
Ras Signaling ◽  
Urea Treatment ◽  
Erk Phosphorylation ◽  
Ras Activation ◽  
Gene Assay

The small guanine nucleotide-binding protein Ras, activated by peptide mitogens and other stimuli, regulates downstream signaling events to influence transcription. The role of Ras in solute signaling to gene regulation was investigated in the murine inner medullary collecting duct (mIMCD3) cell line. Urea treatment (100–200 mM), but not sham treatment, increased Ras activation 124% at 2 min; the effect of NaCl did not achieve statistical significance. To determine the contribution of Ras activation to urea-inducible signal transduction, mIMCD3 cells were stably transfected with an expression plasmid encoding a dominant negative-acting N17Ras mutant driven by a dexamethasone-inducible (murine mammary tumor virus) promoter. After 24 h of induction, selected cell lines exhibited sufficient N17Ras overexpression to abolish epidermal growth factor- and hypotonicity-mediated signaling to extracellular signal-regulated kinase (ERK) phosphorylation, as determined by immunoblotting. Conditional N17Ras overexpression inhibited urea- and NaCl-inducible ERK phosphorylation by 40–50%, but only at 15 min, and not 5 min, of treatment. N17Ras induction, however, almost completely inhibited urea-inducible Egr-1 transcription, as quantitated by luciferase reporter gene assay, but failed to influence tonicity-inducible (TonE-mediated) transcription. N17Ras overexpression also blocked urea-inducible expression of the transcription factor Gadd153 but did not influence osmotic or urea-inducible apoptosis. In addition, urea treatment induced recruitment of the Ras activator Sos to the plasma membrane. Taken together, these observations suggest a role for Ras signaling in the IMCD cell response to urea stress.

scholarly journals Visualization of Negative Signaling in B Cells by Quantitative Confocal Microscopy

2001 ◽  
Vol 21 (24) ◽  
pp. 8615-8625 ◽  
Author(s):  
Hyewon Phee ◽  
William Rodgers ◽  
K. Mark Coggeshall
Keyword(s):  
B Cells ◽  
B Cell ◽  
Actin Polymerization ◽  
Cell Activation ◽  
Ex Vivo ◽  
Sh2 Domain ◽  
Dominant Negative ◽  
Receptor Internalization ◽  
Dominant Negative Mutant ◽  
Mutant Form

ABSTRACT Numerous biochemical experiments have invoked a model in which B-cell antigen receptor (BCR)-Fc receptor for immunoglobulin (Ig) G (FcγRII) coclustering provides a dominant negative signal that blocks B-cell activation. Here, we tested this model using quantitative confocal microscopic techniques applied to ex vivo splenic B cells. We found that FcγRII and BCR colocalized with intact anti-Ig and that the SH2 domain-containing inositol 5′-phosphatase (SHIP) was recruited to the same site. Colocalization of BCR and SHIP was inefficient in FcγRII−/− but not gamma chain−/− splenic B cells. We also examined the subcellular location of a variety of enzymes and adapter proteins involved in signal transduction. Several proteins (CD19, CD22, SHP-1, and Dok) and a lipid raft marker were corecruited to the BCR, regardless of the presence or absence of FcγRII and SHIP. Other proteins (Btk, Vav, Rac, and F-actin) displayed reduced colocalization with BCR in the presence of FcγRII and SHIP. Colocalization of BCR and F-actin required phosphatidylinositol (PtdIns) 3-kinase and was inhibited by SHIP, because the block in BCR/F-actin colocalization was not seen in B cells of SHIP−/− animals. Furthermore, BCR internalization was inhibited with intact anti-Ig stimulation or by expression of a dominant-negative mutant form of Rac. From these results, we propose that SHIP recruitment to BCR/FcγRII and the resulting hydrolysis of PtdIns-3,4,5-trisphosphate prevents the appropriate spatial redistribution and activation of enzymes distal to PtdIns 3-kinase, including those that promote Rac activation, actin polymerization, and receptor internalization.

scholarly journals p19Arf induces p53-dependent apoptosis during Abelson virus-mediated pre-B cell transformation

1998 ◽  
Vol 95 (22) ◽  
pp. 13194-13199 ◽  
Author(s):  
A. Radfar ◽  
I. Unnikrishnan ◽  
H.-W. Lee ◽  
R. A. DePinho ◽  
N. Rosenberg
Keyword(s):  
B Cell ◽  
Cell Transformation ◽  
Abelson Virus

scholarly journals Vav3 Modulates B Cell Receptor Responses by Regulating Phosphoinositide 3-Kinase Activation

2002 ◽  
Vol 195 (2) ◽  
pp. 189-200 ◽  
Author(s):  
Kazunori Inabe ◽  
Masamichi Ishiai ◽  
Andrew M. Scharenberg ◽  
Norman Freshney ◽  
Julian Downward ◽  
...  
Keyword(s):  
B Cell ◽  
Cell Receptor ◽  
Sh2 Domain ◽  
Dominant Negative ◽  
Calcium Flux ◽  
Inositol Polyphosphate ◽  
Kinase Activation ◽  
Dominant Negative Form ◽  
Phosphoinositide 3 Kinase ◽  
Jnk Activation

To elucidate the mechanism(s) by which Vav3, a new member of the Vav family proteins, participates in B cell antigen receptor (BCR) signaling, we have generated a B cell line deficient in Vav3. Here we report that Vav3 influences phosphoinositide 3-kinase (PI3K) function through Rac1 in that phosphatidylinositol-3,4,5-trisphosphate (PIP3) generation was attenuated by loss of Vav3 or by expression of a dominant negative form of Rac1. The functional interaction between PI3K and Rac1 was also demonstrated by increased PI3K activity in the presence of GTP-bound Rac1. In addition, we show that defects of calcium mobilization and c-Jun NH2-terminal kinase (JNK) activation in Vav3-deficient cells are relieved by deletion of a PIP3 hydrolyzing enzyme, SH2 domain-containing inositol polyphosphate 5′-phosphatase (SHIP). Hence, our results suggest a role for Vav3 in regulating the B cell responses by promoting the sustained production of PIP3 and thereby calcium flux.

scholarly journals Active Akt and Functional p53 Modulate Apoptosis in Abelson Virus-Transformed Pre-B Cells

2004 ◽  
Vol 78 (4) ◽  
pp. 1636-1644 ◽  
Author(s):  
Li Gong ◽  
Indira Unnikrishnan ◽  
Anuradha Raghavan ◽  
Kalindi Parmar ◽  
Naomi Rosenberg
Keyword(s):  
B Cells ◽  
Protein Tyrosine Kinase ◽  
Leukemia Virus ◽  
Temperature Shift ◽  
Kinase Domain ◽  
Transformation Process ◽  
Sh2 Domain ◽  
Temperature Sensitive ◽  
Nonpermissive Temperature ◽  
Src Homology

ABSTRACT Suppression of apoptosis is an important feature of the Abelson murine leukemia virus (Ab-MLV) transformation process. During multistep transformation, Ab-MLV-infected pre-B cells undergo p53-dependent apoptosis during the crisis phase of transformation. Even once cells are fully transformed, an active v-Abl protein tyrosine kinase is required to suppress apoptosis because cells transformed by temperature-sensitive (ts) kinase mutants undergo rapid apoptosis after a shift to the nonpermissive temperature. However, inactivation of the v-Abl protein by a temperature shift interrupts signals transmitted via multiple pathways, making it difficult to identify those that are critically important for the suppression of apoptosis. To begin to dissect these pathways, we tested the ability of an SH2 domain Ab-MLV mutant, P120/R273K, to rescue aspects of the ts phenotype of pre-B cells transformed by the conditional kinase domain mutant. The P120/R273K mutant suppressed apoptosis at the nonpermissive temperature, a phenotype correlated with its ability to activate Akt. Apoptosis also was suppressed at the nonpermissive temperature by constitutively active Akt and in p53-null pre-B cells transformed with the ts kinase domain mutant. These data indicate that an intact Src homology 2 (SH2) domain is not critical for apoptosis suppression and suggest that signals transmitted through Akt and p53 play an important role in the response.

scholarly journals Slap Negatively Regulates Src Mitogenic Function but Does Not Revert Src-Induced Cell Morphology Changes

2000 ◽  
Vol 20 (10) ◽  
pp. 3396-3406 ◽  
Author(s):  
Gaël Manes ◽  
Paul Bello ◽  
Serge Roche
Keyword(s):  
Dna Synthesis ◽  
Cell Transformation ◽  
Sh2 Domain ◽  
Fiber Formation ◽  
Dominant Negative ◽  
Negative Regulator ◽  
C Terminus ◽  
Factor C

ABSTRACT Src-like adapter protein (Slap) is a recently identified protein that negatively regulates mitogenesis in murine fibroblasts (S. Roche, G. Alonso, A. Kazlausakas, V. M. Dixit, S. A. Courtneidge, and A. Pandey, Curr. Biol. 8:975–978, 1998) and comprises an SH3 and SH2 domain with striking identity to the corresponding Src domains. In light of this, we sought to investigate whether Slap could be an antagonist of all Src functions. Like Src, Slap was found to be myristylated in vivo and largely colocalized with Src when coexpressed in Cos7 cells. Microinjection of a Slap-expressing construct into quiescent NIH 3T3 cells inhibited platelet-derived growth factor (PDGF)-induced DNA synthesis, and the inhibition was rescued by the transcription factor c-Myc but not by c-Jun/c-Fos expression. Fyn (or Src) overexpression overrides the G1/S block induced by both SrcK− and a Slap mutant with a deletion of its C terminus (SlapΔC), but not the block induced by Slap or SlapΔSH3, implying that the C terminus is a noncompetitive inhibitor of Src mitogenic function. Furthermore, a chimeric adapter comprising SrcΔK fused to the Slap C terminus (Src/SlapC) also inhibited Src function during the PDGF response in a noncompetitive manner, as Src coexpression could not rescue PDGF signaling. Slap, however, did not reverse deregulated Src-induced cell transformation, as it was unable to inhibit depolymerization of actin stress fibers while still being able to inhibit SrcY527F-induced DNA synthesis. This was attributed to a distinct Slap SH3 binding specificity, since the chimeric Slap/SrcSH3 molecule, in which the Slap SH3 was replaced by the Src SH3 sequence, substantially restored stress fiber formation. Indeed, three amino acids important for ligand binding in Src SH3 were replaced in the Slap SH3 sequence; Slap SH3 did not bind to the Src SH3 partners p85α, Shc, and Sam68 in vitro, and the chimeric tyrosine kinase Slap/SrcK, composed of SlapΔC fused to the SH2 linker kinase sequence of Src, was not regulated in vivo. Furthermore, the Src SH3 domain is required for signaling during mitogenesis and since Slap/SrcK behaved as a dominant negative in the PDGF mitogenic response when microinjected into quiescent fibroblasts. We conclude that Slap is a negative regulator of Src during mitogenesis involving both the SH2 and the C terminus domains in a noncompetitive manner, but it does not regulate all Src function due to specific SH3 binding substrates.

Aberrant Splicing of the SLP65 SH2 Domain Enables Pre-B Cell Transformation and Compromises the Leukemia-Suppressive Function of the Pre-B Cell Receptor

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 294-294
Author(s):  
Cihangir Duy ◽  
Lars Klemm ◽  
Rahul Nahar ◽  
Peter van Essen ◽  
Mieke Sprangers ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Receptor ◽  
Sh2 Domain ◽  
B Cell Receptor ◽  
Dominant Negative ◽  
Full Length ◽  
Aberrant Splicing ◽  
Cell Stage ◽  
Suppressive Function

Abstract The linker molecule SLP65 is critical for pre-B cell receptor-mediated differentiation signals during early B cell development. Germline mutations of the SLP65 gene in mice and humans result in a profound differentiation block at an early pre-B cell stage. Likewise, B cell lineage acute lymphoblast leukemia (ALL) cells are phenotypically arrested at an early pre-B cell stage in the vast majority of cases. In about 2–5% of cases with ALL, mutations and deletions of the SLP65 gene are found (Sprangers et al., 2006; Mullighan et al., 2007). In a comprehensive study of SLP65 function in human ALL cells, we identified numerous aberrant SLP65 splice variants, which all lack one or more exons that encode the C-terminal SLP65 SH2 domain. A splice variant lacking exon 16, which encodes the central part of the SH2 domain was particularly abundant in ALL but not in normal pre-B cells (EMBL/GenBank Accession number AM180337). The SH2 domain may have critical function because it represents the main ligand for the non-ITAM Y204 in the Igα (CD79A) signaling chain of the pre-B cell receptor (Patterson et al., 2006) and thereby connects the pre-B cell receptor to downstream signaling molecules. To examine a potential role of the SLP65 SH2 domain during the process of malignant transformation in ALL, we measured mRNA levels of full-length SLP65 vs SLP65 splice variants, in which the SH2 domain was deleted (SLP65ΔSH2) in normal pre-B cells and primary human ALL cells by quantitative RT-PCR. While normal pre-B cells express full-length SLP65 at high and SLP65ΔSH2 at very low levels, the SLP65/SLP65ΔSH2 ratio was reduced in E2A-PBX1-driven ALL and particularly low in BCR-ABL1-driven ALL. Given that SLP65ΔSH2 is overexpressed in ALL cells at the expense of full-length SLP65, we investigated biochemical properties of SLP65ΔSH2. To this end, we transduced Slp65−/− pre-B cells with either full-length Slp65, SLP65ΔSH2 or a GFP empty vector control. As opposed to full-length SLP65, SLP65ΔSH2 does not interact with Igα and does not confer tyrosine phosphorylation of BTK downstream of the pre-B cell receptor. Also Ca2+-release in response to pre-B cell receptor engagement and induction of differentiation was drastically reduced in Slp65−/− pre-B cells that were reconstituted with SLP65ΔSH2 instead of SLP65. Co-expression experiments with SLP65 showed that SLP65ΔSH2 has a dominant-negative function and impairs pre-B cell receptor signaling. We next transformed Slp65−/− pre-B cells with a retroviral BCR-ABL1 vector and tested whether SLP65 and SLP65ΔSH2 have a different impact on BCR-ABL1-mediated pre-B cell transformation and BCR-ABL1-driven leukemic growth. Reconstitution of SLP65 expression in Slp65−/− BCR-ABL1-transformed pre-B ALL cells resulted in cell death and nine days after transduction more than 90% of the SLP65-transduced cells had undergone apoptosis. Conversely, reconstitution of Slp65−/− BCR-ABL1-transformed pre-B ALL cells with SLP65ΔSH2 had no significant effect on viability of the leukemia cells. In a titration experiment, we reconstituted SLP65−/−BCR-ABL1-driven ALL cells with SLP65 and SLP65ΔSH2 at various ratios and thereby confirmed that SLP65ΔSH2 has a dominant-negative effect and compromises the leukemia-suppressive function of the pre-B cell receptor. We next tested whether aberrant splicing also interferes with the tumor suppressor function of SLP65 in vivo: To this end, we engrafted SLP65−/−BCR-ABL1- driven ALL cells that were transduced with either SLP65-GFP, SLP65ΔSH2 or GFP into sublethally irradiated NOD/SCID mice. After 24 days, mice that were engrafted with ALL cells transduced with SLP65ΔSH2 or GFP became terminally leukemic, whereas mice injected with SLP65-transduced ALL cells showed no signs of disease. At this time, all mice were sacrificed and analyzed. Whereas mice with SLP65ΔSH2- or GFP-transduced ALL cells had enlarged spleens and substantial leukemic infiltration of the bone marrow (79 and 81% leukemia cell content), leukemic infitration was reduced if SLP65-transduced ALL cells were injected (1.8% leukemia infiltration). Whereas mutations and deletions of the SLP65 gene are rare, we conclude that aberrant splicing of the SLP65 SH2 domain represents a common mechanism in ALL cells to compromise the leukemia-suppressive function of the pre-B cell receptor.

Gfi1 as a Regulator of Hematopoietic Differentiation.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. sci-16-sci-16
Author(s):  
H. Leighton Grimes ◽  
Chinavenmeni S. Velu ◽  
Shane Horman ◽  
Aditya Chaubey ◽  
Tristan Bourdeau ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cell ◽  
Target Genes ◽  
Cell Transformation ◽  
Bone Marrow Failure ◽  
Leukemia Virus ◽  
Dominant Negative ◽  
Insertion Mutagenesis ◽  
Loss Of Function ◽  
Mutant Proteins

Abstract Growth Factor Independent-1 (Gfi1) is a transcriptional repressor originally identified as a target of Moloney leukemia virus insertion mutagenesis. Gfi1 potently collaborates with Myc and Pim oncogenes to mediate T cell transformation. Retroviral insertions which activate Gfi1 are among the most frequent events in MoMLV-induced T cell, but not myeloid, leukemias. Orthologous proteins in Drosophila (Senseless) and C.elegans (Pag-3) are key regulators of developmental decisions. Gfi1−/− mice display lymphopenia, neutropenia, and abnormally proliferative HSC and progenitors which eventually lead to bone marrow failure. Humans with bone marrow failure syndromes, such as Severe Congenital Neutropenia or Non-Immune Chronic Idiopathic Neutropenia of Adults, display mutations in GFI1, which produce dominant negative acting GFI1 proteins. The SCN-associated GFI1N382S mutant proteins derepress a subset of GFI1 target genes, including CSF1 and CSF1R, to block granulopoeisis. Normally, Gfi1 antagonizes monopoiesis mediated by Pu.1, Egr1, Egr2, and Nab2. Thus, Gfi1 loss of function may impair granulopoiesis by failing to successfully repress monopoeitic differentiation. GFI1 dysfunction may also underlie Specific Granule Deficiency. GFI1 is able to synergize with C/EBP transcription factors to activate genes, such as neutrophil collagenase. Gfi1 may, therefore, enhance granulopoietic differentiation through C/EBP factors. Though great progress has been made in understanding Gfi1 biological and biochemical functions, we are only beginning to understand the role of Gfi1 in integrating hematopoietic transcriptional programming. We find that Gfi1 signaling controls both the differentiation and transformation of myeloid progenitors through an evolutionarily conserved transcriptional and post-transcriptional network.

scholarly journals The Extreme Carboxyl Terminus of v-Abl Is Required for Lymphoid Cell Transformation by Abelson Virus

2003 ◽  
Vol 77 (8) ◽  
pp. 4617-4625 ◽  
Author(s):  
David Warren ◽  
Deborah S. Griffin ◽  
Celine Mainville ◽  
Naomi Rosenberg
Keyword(s):  
B Cells ◽  
Protein Tyrosine Kinase ◽  
Cell Transformation ◽  
Leukemia Virus ◽  
Fibroblast Cell ◽  
Lymphoid Cells ◽  
Carboxyl Terminus ◽  
Nih 3T3

ABSTRACT The v-Abl protein tyrosine kinase encoded by Abelson murine leukemia virus (Ab-MLV) induces transformation of pre-B cells in vivo and in vitro and can transform immortalized fibroblast cell lines in vitro. Although the kinase activity of the protein is required for these events, most previously studied mutants encoding truncated v-Abl proteins that lack the extreme carboxyl terminus retain high transforming capacity in NIH 3T3 cells but transform lymphocytes poorly. To understand the mechanisms responsible for poor lymphoid transformation, mutants expressing a v-Abl protein lacking portions of the COOH terminus were compared for their ability to transform pre-B cells. Although all mutants lacking sequences within the COOH terminus were compromised for lymphoid transformation, loss of amino acids in the central region of the COOH terminus, including those implicated in JAK interaction and DNA binding, decreased transformation twofold or less. In contrast, loss of the extreme COOH terminus rendered the protein unstable and led to rapid proteosome-mediated degradation, a feature that was more prominent when the protein was expressed in Ab-MLV-transformed lymphoid cells. These data indicate that the central portion of the COOH terminus is not essential for lymphoid transformation and reveal that one important function of the COOH terminus is to stabilize the v-Abl protein in lymphoid cells.

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