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Kim BH, Jee JG, Yin CH, Sandoval C, Jayabose S, Kitamura D, Bach EA, Baeg GH. NSC114792, a novel small molecule identified through structure-based computational database screening, selectively inhibits JAK3. Mol Cancer 2010; 9:36. [PMID: 20149240 PMCID: PMC2830973 DOI: 10.1186/1476-4598-9-36] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Accepted: 02/11/2010] [Indexed: 01/10/2023] Open
Abstract
Background Human or animals lacking either JAK3 or the common gamma chain (γc) expression display severe combined immunodeficiency disease, indicating the crucial role of JAK3 in T-cell development and the homeostasis of the immune system. JAK3 has also been suggested to contribute to the pathogenesis of tumorigenesis. Recent studies identified activating JAK3 mutations in patients with various hematopoietic malignancies, including acute megakaryoblastic leukemia. Importantly, functional analyses of some of those JAK3 mutations have been shown to cause lethal hematopoietic malignancies in animal models. These observations make JAK3 an ideal therapeutic target for the treatment of various human diseases. To identify novel small molecule inhibitors of JAK3, we performed structure-based virtual screen using the 3D structure of JAK3 kinase domain and the NCI diversity set of compounds. Results We identified NSC114792 as a lead compound. This compound directly blocked the catalytic activity of JAK3 but not that of other JAK family members in vitro. In addition, treatment of 32D/IL-2Rβ cells with the compound led to a block in IL-2-dependent activation of JAK3/STAT5 but not IL-3-dependent activation of JAK2/STAT5. Consistent with the specificity of NSC114792 for JAK3, it selectively inhibited persistently-activated JAK3, but failed to affect the activity of other JAK family members and other oncogenic kinases in various cancer cell lines. Finally, we showed that NSC114792 decreases cell viability by inducing apoptosis through down-regulating anti-apoptotic gene expression only in cancer cells harboring persistently-active JAK3. Conclusions NSC114792 is a lead compound that selectively inhibits JAK3 activity. Therefore, our study suggests that this small molecule inhibitor of JAK3 can be used as a starting point to develop a new class of drugs targeting JAK3 activity, and may have therapeutic potential in various diseases that are caused by aberrant JAK3 activity.
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Affiliation(s)
- Byung-Hak Kim
- Department of Pediatrics, Division of Hematology/Oncology, New York Medical College, Valhalla, New York 10595, USA
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STAT3 is a substrate of SYK tyrosine kinase in B-lineage leukemia/lymphoma cells exposed to oxidative stress. Proc Natl Acad Sci U S A 2010; 107:2902-7. [PMID: 20133729 DOI: 10.1073/pnas.0909086107] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
We provide unprecedented genetic and biochemical evidence that the antiapoptotic transcription factor STAT3 serves as a substrate for SYK tyrosine kinase both in vitro and in vivo. Induction of SYK in an ecdysone-inducible mammalian expression system results in STAT3 activation, as documented by tyrosine phosphorylation and nuclear translocation of STAT3, as well as amplified expression of several STAT3 target genes. STAT3 activation after oxidative stress (OS) is strongly diminished in DT40 chicken B-lineage lymphoma cells rendered SYK-deficient by targeted disruption of the syk gene. Introduction of a wild-type, C-terminal or N-terminal SH2 domain-mutated, but not a kinase domain-mutated, syk gene into SYK-deficient DT40 cells restores OS-induced enhancement of STAT-3 activity. Thus, SYK plays an important and indispensable role in OS-induced STAT3 activation and its catalytic SH1 domain is critical for this previously unknown regulatory function. These results provide evidence for the existence of a novel mode of cytokine-independent cross-talk that operates between SYK and STAT3 pathways and regulates apoptosis during OS. We further provide experimental evidence that SYK is capable of associating with and phosphorylating STAT3 in human B-lineage leukemia/lymphoma cells challenged with OS. In agreement with a prerequisite role of SYK in OS-induced STAT3 activation, OS does not induce tyrosine phosphorylation of STAT3 in SYK-deficient human proB leukemia cells. Notably, inhibition of SYK with a small molecule drug candidate prevents OS-induced activation of STAT3 and overcomes the resistance of human B-lineage leukemia/lymphoma cells to OS-induced apoptosis.
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Malignant transformation of Slp65-deficient pre-B cells involves disruption of the Arf-Mdm2-p53 tumor suppressor pathway. Blood 2009; 115:1385-93. [PMID: 20008789 DOI: 10.1182/blood-2009-05-222166] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The adapter protein Slp65 is a key component of the precursor-B (pre-B) cell receptor. Slp65-deficient mice spontaneously develop pre-B cell leukemia, but the mechanism by which Slp65(-/-) pre-B cells become malignant is unknown. Loss of Btk, a Tec-family kinase that cooperates with Slp65 as a tumor suppressor, synergizes with deregulation of the c-Myc oncogene during lymphoma formation. Here, we report that the presence of the immunoglobulin heavy chain transgene V(H)81X prevented tumor development in Btk(-/-)Slp65(-/-) mice. This finding paralleled the reported effect of a human immunoglobulin heavy chain transgene on lymphoma development in Emu-myc mice, expressing transgenic c-Myc. Because activation of c-Myc strongly selects for spontaneous inactivation of the p19(Arf)-Mdm2-p53 tumor suppressor pathway, we investigated whether disruption of this pathway is a common alteration in Slp65(-/-) pre-B cell tumors. We found that combined loss of Slp65 and p53 in mice transformed pre-B cells very efficiently. Aberrations in p19(Arf), Mdm2, or p53 expression were found in all Slp65(-/-) (n = 17) and Btk(-/-)Slp65(-/-) (n = 32) pre-B cell leukemias analyzed. In addition, 9 of 10 p53(-/-)Slp65(-/-) pre-B cell leukemias manifested significant Mdm2 protein expression. These data indicate that malignant transformation of Slp65(-/-) pre-B cells involves disruption of the p19(Arf)-Mdm2-p53 tumor suppressor pathway.
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Nahar R, Müschen M. Pre-B cell receptor signaling in acute lymphoblastic leukemia. Cell Cycle 2009; 8:3874-7. [PMID: 19901533 DOI: 10.4161/cc.8.23.10035] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
B cell lineage ALL represents by far the most frequent malignancy in children and is also common in adults. Despite significant advances over the past four decades, cytotoxic treatment strategies have recently reached a plateau with cure rates at 80 percent for children and 55 percent for adults. Relapse after cytotoxic drug treatment, initial drug-resistance and dose-limiting toxicity are among the most frequent complications of current therapy approaches. For this reason, pathway-specific treatment strategies in addition to cytotoxic drug treatment seem promising to further improve therapy options for ALL patients. In a recent study on 111 cases of pre-B cell-derived human ALL, we found that ALL cells carrying a BCR-ABL1-gene rearrangement lack expression of a functional pre-B cell receptor in virtually all cases. In a proof-of-principle experiment, we studied pre-B cell receptor function during progressive leukemic transformation of pre-B cells in BCR-ABL1-transgenic mice: Interestingly, signaling from the pre-B cell receptor and the oncogenic BCR-ABL1 kinase are mutually exclusive and only "crippled" pre-B cells that fail to express a functional pre-B cell receptor are permissive to transformation by BCR-ABL1.
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Affiliation(s)
- Rahul Nahar
- Leukemia and Lymphoma Program, USC Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA, USA
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55
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Abstract
Antigen receptors on the surface of B lymphocytes trigger adaptive immune responses after encountering their cognate antigens but also control a series of antigen-independent checkpoints during B cell development. These physiological processes are regulated by the expression and function of cell surface receptors, intracellular signaling molecules, and transcription factors. The function of these proteins can be altered by a dynamic array of post-translational modifications, using two interconnected mechanisms. These modifications can directly induce an altered conformational state in the protein target of the modification itself. In addition, they can create new binding sites for other protein partners, thereby contributing to where and when such multiple protein assemblies are activated within cells. As a new type of post-transcriptional regulator, microRNAs have emerged to influence the development and function of B cells by affecting the expression of target mRNAs.
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56
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Trageser D, Iacobucci I, Nahar R, Duy C, von Levetzow G, Klemm L, Park E, Schuh W, Gruber T, Herzog S, Kim YM, Hofmann WK, Li A, Storlazzi CT, Jäck HM, Groffen J, Martinelli G, Heisterkamp N, Jumaa H, Müschen M. Pre-B cell receptor-mediated cell cycle arrest in Philadelphia chromosome-positive acute lymphoblastic leukemia requires IKAROS function. ACTA ACUST UNITED AC 2009; 206:1739-53. [PMID: 19620627 PMCID: PMC2722172 DOI: 10.1084/jem.20090004] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
B cell lineage acute lymphoblastic leukemia (ALL) arises in virtually all cases from B cell precursors that are arrested at pre–B cell receptor–dependent stages. The Philadelphia chromosome–positive (Ph+) subtype of ALL accounts for 25–30% of cases of adult ALL, has the most unfavorable clinical outcome among all ALL subtypes and is defined by the oncogenic BCR-ABL1 kinase and deletions of the IKAROS gene in >80% of cases. Here, we demonstrate that the pre–B cell receptor functions as a tumor suppressor upstream of IKAROS through induction of cell cycle arrest in Ph+ ALL cells. Pre–B cell receptor–mediated cell cycle arrest in Ph+ ALL cells critically depends on IKAROS function, and is reversed by coexpression of the dominant-negative IKAROS splice variant IK6. IKAROS also promotes tumor suppression through cooperation with downstream molecules of the pre–B cell receptor signaling pathway, even if expression of the pre–B cell receptor itself is compromised. In this case, IKAROS redirects oncogenic BCR-ABL1 tyrosine kinase signaling from SRC kinase-activation to SLP65, which functions as a critical tumor suppressor downstream of the pre–B cell receptor. These findings provide a rationale for the surprisingly high frequency of IKAROS deletions in Ph+ ALL and identify IKAROS-mediated cell cycle exit as the endpoint of an emerging pathway of pre–B cell receptor–mediated tumor suppression.
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Affiliation(s)
- Daniel Trageser
- Leukemia and Lymphoma Program, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90027, USA
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Herzog S, Reth M, Jumaa H. Regulation of B-cell proliferation and differentiation by pre-B-cell receptor signalling. Nat Rev Immunol 2009; 9:195-205. [PMID: 19240758 DOI: 10.1038/nri2491] [Citation(s) in RCA: 230] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The pre-B-cell receptor (pre-BCR) is expressed following the productive recombination of the immunoglobulin heavy chain gene. Signals through the pre-BCR are required for initiating diverse processes in pre-B cells, including proliferation and recombination of the light chain gene, which eventually lead to the differentiation of pre-B cells to immature B cells. However, the molecular mechanisms by which the pre-BCR promotes these processes remain largely unresolved. Recent findings suggest that forkhead box O (FOXO) transcription factors connect pre-BCR signalling to the activation of the recombination machinery. In this Review, we discuss how FOXO transcription factors are regulated by the pre-BCR to allow the progression of the cell cycle and the recombination of the light chain gene.
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Affiliation(s)
- Sebastian Herzog
- Centre for Biological Signalling Studies, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
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58
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Impaired B-cell development at the pre-BII-cell stage in galectin-1-deficient mice due to inefficient pre-BII/stromal cell interactions. Blood 2009; 113:5878-86. [PMID: 19329777 DOI: 10.1182/blood-2009-01-198465] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Activation of the pre-B-cell receptor (pre-BCR) in the bone marrow depends on both tonic and ligand-induced signaling and leads to pre-BII-cell proliferation and differentiation. Using normal mouse bone marrow pre-BII cells, we demonstrate that the ligand-induced pre-BCR activation depends on pre-BCR/galectin-1/integrin interactions leading to pre-BCR clustering at the pre-BII/stromal cell synapse. In contrast, heparan sulfates, shown to be pre-BCR ligands in mice, are not implicated in pre-BCR relocalization. Inhibition of pre-BCR/galectin-1/integrin interactions has functional consequences, since pre-BII-cell proliferation and differentiation are impaired in an in vitro B-cell differentiation assay, without affecting cellular apoptosis. Most strikingly, although galectin-1-deficient mice do not show an apparent B-cell phenotype, the kinetics of de novo B-cell reconstitution after hydroxyurea treatment indicates a specific delay in pre-BII-cell recovery due to a decrease in pre-BII-cell differentiation and proliferation. Thus, although it remains possible that the pre-BCR interacts with other ligands, these results highlight the role played by the stromal cell-derived galectin-1 for the efficient development of normal pre-BII cells and suggest the existence of pre-BII-specific stromal cell niches in normal bone marrow.
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60
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Abstract
Pre-B-cell leukemia spontaneously develops in BLNK-deficient mice, and pre-B-cell acute lymphoblastic leukemia cells in children often lack BLNK protein expression, demonstrating that BLNK functions as a tumor suppressor. However, the mechanism by which BLNK suppresses pre-B-cell leukemia, as well as the identification of other genetic alterations that collaborate with BLNK deficiency to cause leukemogenesis, are still unknown. Here, we demonstrate that the JAK3/STAT5 signaling pathway is constitutively activated in pre-B leukemia cells derived from BLNK(-/-) mice, mostly due to autocrine production of IL-7. Inhibition of IL-7R signaling or JAK3/STAT5 activity resulted in the induction of p27(kip1) expression and cell-cycle arrest, accompanied by apoptosis in the leukemia cells. Transgene-derived constitutively active STAT5 (STAT5b-CA) strongly synergized with the loss of BLNK to initiate leukemia in vivo. In the leukemia cells, exogenously expressed BLNK inhibited autocrine JAK3/STAT5 signaling, resulting in p27(kip1) induction, cell-cycle arrest, and apoptosis. BLNK-inhibition of JAK3 was dependent on the binding of BLNK to JAK3. These data indicate that BLNK normally regulates IL-7-dependent proliferation and survival of pre-B cells through direct inhibition of JAK3. Thus, somatic loss of BLNK and concomitant mutations leading to constitutive activation of Jak/STAT5 pathway result in the generation of pre-B-cell leukemia.
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61
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Kamino H, Futamura M, Nakamura Y, Kitamura N, Kabu K, Arakawa H. B-cell linker protein prevents aneuploidy by inhibiting cytokinesis. Cancer Sci 2008; 99:2444-54. [PMID: 19018766 PMCID: PMC11158510 DOI: 10.1111/j.1349-7006.2008.00990.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Revised: 08/14/2008] [Accepted: 08/15/2008] [Indexed: 11/30/2022] Open
Abstract
Aneuploidy is a hallmark of human cancers. Although the maintenance of genomic integrity by p53 is important in preventing aneuploidy, its mechanism remains to be elucidated. Here we report evidence that B-cell linker protein (BLNK) mediates the inhibition of cytokinesis, which generates tetraploidy but prevents aneuploidy. We identified BLNK as a transcriptional target of p53. Surprisingly, ectopic expression of exogenous BLNK inhibited cytokinesis, resulting in the formation of tetraploid cells. Indeed, BLNK was involved in the generation of spontaneously arising binucleate tetraploid cells. Interestingly, cytokinesis after DNA damage was inhibited in p21(-/-) and p53+/+ cells, but not in p53(-/-) cells. BLNK knockdown in p53+/+ and p21(-/-) cells enhanced cytokinesis after DNA damage, leading to the generation of aneuploid cells. In addition, a BLNK-downregulated human pre-B leukemia cell line showed increased cytokinesis and aneuploidy after DNA damage compared with two other pre-B leukemia cell lines expressing higher levels of BLNK. These results suggest that BLNK acts as a mediator of p53 in the inhibition of cytokinesis, which prevents aneuploidy. We propose that the inhibition of cytokinesis is crucial for the maintenance of genomic integrity.
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Affiliation(s)
- Hiroki Kamino
- Cancer Medicine and Biophysics Division, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan
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62
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Spatuzza C, Schiavone M, Di Salle E, Janda E, Sardiello M, Fiume G, Fierro O, Simonetta M, Argiriou N, Faraonio R, Capparelli R, Quinto I, Scala G. Physical and functional characterization of the genetic locus of IBtk, an inhibitor of Bruton's tyrosine kinase: evidence for three protein isoforms of IBtk. Nucleic Acids Res 2008; 36:4402-16. [PMID: 18596081 PMCID: PMC2490745 DOI: 10.1093/nar/gkn413] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Bruton's tyrosine kinase (Btk) is required for B-cell development. Btk deficiency causes X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency (Xid) in mice. Btk lacks a negative regulatory domain and may rely on cytoplasmic proteins to regulate its activity. Consistently, we identified an inhibitor of Btk, IBtk, which binds to the PH domain of Btk and down-regulates the Btk kinase activity. IBtk is an evolutionary conserved protein encoded by a single genomic sequence at 6q14.1 cytogenetic location, a region of recurrent chromosomal aberrations in lymphoproliferative disorders; however, the physical and functional organization of IBTK is unknown. Here, we report that the human IBTK locus includes three distinct mRNAs arising from complete intron splicing, an additional polyadenylation signal and a second transcription start site that utilizes a specific ATG for protein translation. By northern blot, 5′RACE and 3′RACE we identified three IBTKα, IBTKβ and IBTKγ mRNAs, whose transcription is driven by two distinct promoter regions; the corresponding IBtk proteins were detected in human cells and mouse tissues by specific antibodies. These results provide the first characterization of the human IBTK locus and may assist in understanding the in vivo function of IBtk.
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Affiliation(s)
- Carmen Spatuzza
- Department of Experimental and Clinical Medicine, University of Catanzaro Magna Graecia, 88100 Catanzaro, Italy
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63
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Shinohara M, Koga T, Okamoto K, Sakaguchi S, Arai K, Yasuda H, Takai T, Kodama T, Morio T, Geha RS, Kitamura D, Kurosaki T, Ellmeier W, Takayanagi H. Tyrosine kinases Btk and Tec regulate osteoclast differentiation by linking RANK and ITAM signals. Cell 2008; 132:794-806. [PMID: 18329366 DOI: 10.1016/j.cell.2007.12.037] [Citation(s) in RCA: 238] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Revised: 11/08/2007] [Accepted: 12/27/2007] [Indexed: 12/24/2022]
Abstract
Certain autoimmune diseases result in abnormal bone homeostasis, but association of immunodeficiency with bone is poorly understood. Osteoclasts, which derive from bone marrow cells, are under the control of the immune system. Differentiation of osteoclasts is mainly regulated by signaling pathways activated by RANK and immune receptors linked to ITAM-harboring adaptors. However, it is unclear how the two signals merge to cooperate in osteoclast differentiation. Here we report that mice lacking the tyrosine kinases Btk and Tec show severe osteopetrosis caused by a defect in bone resorption. RANK and ITAM signaling results in formation of a Btk(Tec)/BLNK(SLP-76)-containing complex and PLCgamma-mediated activation of an essential calcium signal. Furthermore, Tec kinase inhibition reduces osteoclastic bone resorption in models of osteoporosis and inflammation-induced bone destruction. Thus, this study reveals the importance of the osteoclastogenic signaling complex composed of tyrosine kinases, which may provide the molecular basis for a new therapeutic strategy.
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Affiliation(s)
- Masahiro Shinohara
- Department of Cell Signaling, Graduate School, Tohoku University, Seiryo-machi 4-1, Aoba-ku, Sendai, Miyagi 980-8575, Japan
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64
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Abstract
In addition to the important observations relating immunoglobulin (Ig) mutation status to clinical behavior, studies on the Ig expressed in chronic lymphocytic leukemia (CLL) have revealed compelling evidence that antigen selection contributes to the pathogenesis of this disease. CLL cells that use unmutated Ig can generally be distinguished from CLL cells that use Ig with somatic mutations by expression of the 70-kD zeta-associated protein (ZAP-70). ZAP-70 apparently enhances the capacity of CLL cells to respond to antigen, and therefore might play a causal role in the relatively aggressive clinical behavior noted for patients who have CLL cells that use unmutated Ig. Clinical surveys have found that expression of ZAP-70 by CLL cells is apparently a stronger predictor of early disease progression than is the use by CLL cells of unmutated Ig. As such, strategies that respectively monitor or target Ig-receptor signaling in CLL might be very useful in the risk assessment or treatment of this disease.
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MESH Headings
- Disease Progression
- Humans
- Immunoglobulin Heavy Chains/biosynthesis
- Immunoglobulin Variable Region/biosynthesis
- Leukemia, Lymphocytic, Chronic, B-Cell/genetics
- Leukemia, Lymphocytic, Chronic, B-Cell/immunology
- Receptors, Antigen, B-Cell/genetics
- Receptors, Antigen, B-Cell/immunology
- Signal Transduction
- ZAP-70 Protein-Tyrosine Kinase/physiology
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Affiliation(s)
- Thomas J Kipps
- UCSD Moores Cancer Center, Division of Hematology/Oncology, Department of Medicine, 3855 Health Sciences Drive, #0820, University of California, San Diego, La Jolla, CA 92093-0820, USA.
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Ostler KR, Davis EM, Payne SL, Gosalia BB, Expósito-Céspedes J, Le Beau MM, Godley LA. Cancer cells express aberrant DNMT3B transcripts encoding truncated proteins. Oncogene 2007; 26:5553-63. [PMID: 17353906 PMCID: PMC2435620 DOI: 10.1038/sj.onc.1210351] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Revised: 01/17/2007] [Accepted: 01/17/2007] [Indexed: 12/21/2022]
Abstract
Cancer cells display an altered distribution of DNA methylation relative to normal cells. Certain tumor suppressor gene promoters are hypermethylated and transcriptionally inactivated, whereas repetitive DNA is hypomethylated and transcriptionally active. Little is understood about how the abnormal DNA methylation patterns of cancer cells are established and maintained. Here, we identify over 20 DNMT3B transcripts from many cancer cell lines and primary acute leukemia cells that contain aberrant splicing at the 5' end of the gene, encoding truncated proteins lacking the C-terminal catalytic domain. Many of these aberrant transcripts retain intron sequences. Although the aberrant transcripts represent a minority of the DNMT3B transcripts present, Western blot analysis demonstrates truncated DNMT3B isoforms in the nuclear protein extracts of cancer cells. To test if expression of a truncated DNMT3B protein could alter the DNA methylation patterns within cells, we expressed DNMT3B7, the most frequently expressed aberrant transcript, in 293 cells. DNMT3B7-expressing 293 cells have altered gene expression as identified by microarray analysis. Some of these changes in gene expression correlate with altered DNA methylation of corresponding CpG islands. These results suggest that truncated DNMT3B proteins could play a role in the abnormal distribution of DNA methylation found in cancer cells.
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Affiliation(s)
- KR Ostler
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, Chicago, IL, USA and
| | - EM Davis
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, Chicago, IL, USA and
| | - SL Payne
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, Chicago, IL, USA and
| | - BB Gosalia
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, Chicago, IL, USA and
| | - J Expósito-Céspedes
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, Chicago, IL, USA and
| | - MM Le Beau
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, Chicago, IL, USA and
- University of Chicago Cancer Research Center, University of Chicago, Chicago, IL, USA
| | - LA Godley
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, Chicago, IL, USA and
- University of Chicago Cancer Research Center, University of Chicago, Chicago, IL, USA
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66
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Halcomb KE, Contreras CM, Hinman RM, Coursey TG, Wright HL, Satterthwaite AB. Btk and phospholipase C gamma 2 can function independently during B cell development. Eur J Immunol 2007; 37:1033-42. [PMID: 17372989 DOI: 10.1002/eji.200636451] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The pre-BCR and the BCR regulate B cell development via a signalosome nucleated by the adaptor protein B cell linker protein (BLNK). Formation of this complex facilitates activation of phospholipase C (PLC) gamma2 by Bruton's tyrosine kinase (Btk). To determine whether Btk and PLCgamma2 also have separate functions, we generated Btk(-/-)PLCgamma2(-/-) mice. They demonstrated a block in development at the pre-B stage and increased pre-BCR surface expression. This phenotype was more severe than that of Btk(-/-) or PLCgamma2(-/-) mice. Although both Btk and PLCgamma2 were required for proliferation of splenic B cells in response to BCR cross-linking, they contributed differently to anti-IgM-induced phosphorylation of ERK. Btk(-/-) and PLCgamma2(-/-) mice each had a reduced frequency of Iglambda-expressing B cells and impaired migration of pre-B cells towards stromal cell-derived factor 1. However, the increase in pre-B cell malignancy that occurs in BLNK(-/-) mice in the absence of Btk was not observed in the absence of PLCgamma2. Thus, Btk and PLCgamma2 act both in concert and independently throughout B cell development.
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Affiliation(s)
- Kristina E Halcomb
- Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390-8884, USA
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67
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Song H, Zhang J, Chiang YJ, Siraganian RP, Hodes RJ. Redundancy in B Cell Developmental Pathways: c-Cbl Inactivation Rescues Early B Cell Development through a B Cell Linker Protein-Independent Pathway. THE JOURNAL OF IMMUNOLOGY 2007; 178:926-35. [PMID: 17202354 DOI: 10.4049/jimmunol.178.2.926] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Deficiency in the adaptor protein B cell linker protein (BLNK) results in a substantial but incomplete block in B cell development, suggesting that alternative pathways exist for B lineage differentiation. Another adaptor protein, c-Cbl, plays a negative regulatory role in several BCR-signaling pathways. We therefore investigated the role of c-Cbl during B cell development and addressed the possibility that redundancies in pathways for B cell differentiation could be further revealed by eliminating negative effects mediated by c-Cbl. Strikingly, c-Cbl inactivation reversed a number of the critical defects in early B cell differentiation that are seen in BLNK-deficient mice. c-Cbl(-/-)BLNK(-/-) mice exhibited normalized down-regulation of pre-BCR and CD43, up-regulation of MHC class II, and augmented L chain rearrangement, resulting in a successful transition from pre-B cells to immature B cells. c-Cbl inactivation also reversed the potentially tumor-predisposing hyperproliferative response of BLNK(-/-) pre-B cells to IL-7. Pre-BCR cross-linking induced enhanced and prolonged tyrosine phosphorylation in c-Cbl(-/-)BLNK(-/-) pre-BCR(+) pre-B cells compared with c-Cbl(+/-)BLNK(-/-) cells, including elevated phosphorylation of Lyn, Syk, Btk, and phospholipase C-gamma2. Our studies suggest that some, but not all, pre-BCR-triggered developmental events can be mediated by BLNK-independent pathways that are negatively regulated by c-Cbl, and further suggest that different events during early B cell development require different strength or duration of pre-BCR signaling.
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Affiliation(s)
- Haifeng Song
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
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68
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Wossning T, Herzog S, Köhler F, Meixlsperger S, Kulathu Y, Mittler G, Abe A, Fuchs U, Borkhardt A, Jumaa H. Deregulated Syk inhibits differentiation and induces growth factor-independent proliferation of pre-B cells. ACTA ACUST UNITED AC 2006; 203:2829-40. [PMID: 17130299 PMCID: PMC2118175 DOI: 10.1084/jem.20060967] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The nonreceptor protein spleen tyrosine kinase (Syk) is a key mediator of signal transduction in a variety of cell types, including B lymphocytes. We show that deregulated Syk activity allows growth factor–independent proliferation and transforms bone marrow–derived pre–B cells that are then able to induce leukemia in mice. Syk-transformed pre–B cells show a characteristic pattern of tyrosine phosphorylation, increased c-Myc expression, and defective differentiation. Treatment of Syk-transformed pre–B cells with a novel Syk-specific inhibitor (R406) reduces tyrosine phosphorylation and c-Myc expression. In addition, R406 treatment removes the developmental block and allows the differentiation of the Syk-transformed pre–B cells into immature B cells. Because R406 treatment also prevents the proliferation of c-Myc–transformed pre–B cells, our data indicate that endogenous Syk kinase activity may be required for the survival of pre–B cells transformed by other oncogenes. Collectively, our data suggest that Syk is a protooncogene involved in the transformation of lymphocytes, thus making Syk a potential target for the treatment of leukemia.
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Affiliation(s)
- Thomas Wossning
- Institute of Biology III, Albert-Ludwigs-University of Freiburg, 79104 Freiburg, and Department of Pediatric Hematology and Oncology, Children's Hospital, Munich, Germany
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69
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Liu BA, Jablonowski K, Raina M, Arcé M, Pawson T, Nash PD. The human and mouse complement of SH2 domain proteins-establishing the boundaries of phosphotyrosine signaling. Mol Cell 2006; 22:851-868. [PMID: 16793553 DOI: 10.1016/j.molcel.2006.06.001] [Citation(s) in RCA: 220] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 05/19/2006] [Accepted: 06/02/2006] [Indexed: 01/07/2023]
Abstract
SH2 domains are interaction modules uniquely dedicated to the recognition of phosphotyrosine sites and are embedded in proteins that couple protein-tyrosine kinases to intracellular signaling pathways. Here, we report a comprehensive bioinformatics, structural, and functional view of the human and mouse complement of SH2 domain proteins. This information delimits the set of SH2-containing effectors available for PTK signaling and will facilitate the systems-level analysis of pTyr-dependent protein-protein interactions and PTK-mediated signal transduction. The domain-based architecture of SH2-containing proteins is of more general relevance for understanding the large family of protein interaction domains and the modular organization of the majority of human proteins.
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Affiliation(s)
- Bernard A Liu
- Ben May Institute for Cancer Research and the Committee on Cancer Biology, The University of Chicago, Chicago, Illinois 60637
| | - Karl Jablonowski
- Ben May Institute for Cancer Research and the Committee on Cancer Biology, The University of Chicago, Chicago, Illinois 60637
| | - Monica Raina
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto M5G 1X5, Canada
| | - Michael Arcé
- Ben May Institute for Cancer Research and the Committee on Cancer Biology, The University of Chicago, Chicago, Illinois 60637
| | - Tony Pawson
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto M5G 1X5, Canada.
| | - Piers D Nash
- Ben May Institute for Cancer Research and the Committee on Cancer Biology, The University of Chicago, Chicago, Illinois 60637.
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70
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Patterson HCK, Kraus M, Kim YM, Ploegh H, Rajewsky K. The B cell receptor promotes B cell activation and proliferation through a non-ITAM tyrosine in the Igalpha cytoplasmic domain. Immunity 2006; 25:55-65. [PMID: 16860757 DOI: 10.1016/j.immuni.2006.04.014] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2006] [Revised: 03/19/2006] [Accepted: 04/18/2006] [Indexed: 01/01/2023]
Abstract
In addition to the tyrosines of the Igalpha and beta immunoreceptor tyrosine-based activation motifs (ITAMs), the evolutionarily conserved Igalpha non-ITAM tyrosine 204 becomes phosphorylated upon antigen recognition by the B cell receptor (BCR). Here we demonstrate that splenic B cells from mice with a targeted mutation of Igalpha Y204 exhibited an isolated defect in T cell-independent B cell activation, proliferation, and antibody response upon BCR engagement, yet normal BCR capping, antigen internalization, antigen presentation, and T cell-dependent antibody production. Mutant B cells, present in normal numbers, exhibited unimpaired BCR-induced spleen tyrosine kinase (Syk) phosphorylation but reduced B cell linker protein (BLNK) phosphorylation, calcium flux, and nuclear factor kappaB (NFkappaB), c-jun N-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK) activation. These results suggest that Igalpha non-ITAM tyrosine 204 promotes a distinct cellular response, namely T-independent B cell proliferation and differentiation via phosphorylation of the adaptor BLNK.
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71
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Grabbe A, Wienands J. Human SLP-65 isoforms contribute differently to activation and apoptosis of B lymphocytes. Blood 2006; 108:3761-8. [PMID: 16912232 DOI: 10.1182/blood-2006-02-005397] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The SH2 domain-containing leukocyte adaptor protein of 65 kDa (SLP-65) is the key effector for signaling downstream of the B-cell antigen receptor (BCR). SLP-65 controls not only B lymphopoiesis and humoral immunity but also possesses a yet poorly defined tumor suppressor activity that is lost in many cases of acute lymphoblastic leukemia. We found that the 2 isoforms of human SLP-65 are differentially involved in positive and negative B-cell signaling. Reconstitution experiments revealed that an atypical SH3 domain-binding motif, which is present in the long but not in the short SLP-65 isoform, mediates association to Grb2 and suppresses activation of mitogen-activated protein kinases p38 and JNK as well as up-regulation of c-Fos expression. In turn, the short isoform activates not only AP1-driven but also NF-kappaB-driven gene transcription more potently than the long isoform. Conversely, the long rather than the short SLP-65 isoform promotes BCR-induced B-cell apoptosis. Our data further delineate the structural requirements of positive and negative SLP-65 signal transduction in normal and neoplastic cells.
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Affiliation(s)
- Annika Grabbe
- Georg August University of Göttingen, Institute of Cellular and Molecular Immunology, Humboldtallee 34, 37073 Göttingen, Germany
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72
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Crespo M, Villamor N, Giné E, Muntañola A, Colomer D, Marafioti T, Jones M, Camós M, Campo E, Montserrat E, Bosch F. ZAP-70 expression in normal pro/pre B cells, mature B cells, and in B-cell acute lymphoblastic leukemia. Clin Cancer Res 2006; 12:726-34. [PMID: 16467082 DOI: 10.1158/1078-0432.ccr-05-1531] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE The ZAP-70 gene is normally expressed in T and natural killer cells, where it is required for the T-cell receptor (TCR) signaling. More recently, it has been described that ZAP-70 contributes to the B-cell development at early stages of B-cell differentiation in mice. The purpose was to investigate the presence of ZAP-70 in normal pro/pre B cells and mature B cells and in tumoral cells from B-acute lymphoblastic leukemias (B-ALL). EXPERIMENTAL DESIGN ZAP-70 expression was ascertained by flow cytometry, immunofluorescence, Western blot, and quantitative reverse transcription-PCR. Analysis of ZAP-70 and other signaling proteins of the pre-TCR/TCR was done by Western blot. RESULTS ZAP-70 was expressed in pro/pre B cells but not in normal mature B cells derived from bone marrow, peripheral blood, or tonsil. Among tumoral cells, ZAP-70 was expressed in 56% of B-ALLs with pro/pre B-cell phenotype and in 4 of 6 Burkitt/ALL lymphomas. In B-ALL cells, expression of CD38 protein correlated with ZAP-70 expression (P = 0.05). Mutational analysis of the ZAP-70 gene revealed the absence of mutations in cases lacking ZAP-70 expression. Moreover, other elements of the pre-TCR/TCR signaling pathway, like LAT and Lck, were also found in B-ALL cells. CONCLUSIONS Among normal B-cell subsets, ZAP-70 was found expressed in normal pro/pre B cells but not in a significant proportion of normal B cells with mature phenotype. Moreover, the presence of ZAP-70 in B-ALLs probably reflects their cellular origin. The lack of ZAP-70 expression in normal mature B cells suggests that its expression in mature-derived neoplasms with different cellular origin, such as Burkitt's lymphoma and chronic lymphocytic leukemia, might be due to an aberrant phenomenon.
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Affiliation(s)
- Marta Crespo
- Department of Hematology, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Hospital Clínic, Barcelona, Spain
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73
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Yamamoto M, Hayashi K, Nojima T, Matsuzaki Y, Kawano Y, Karasuyama H, Goitsuka R, Kitamura D. BASH-novel PKC-Raf-1 pathway of pre-BCR signaling induces kappa gene rearrangement. Blood 2006; 108:2703-11. [PMID: 16794253 DOI: 10.1182/blood-2006-05-024968] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The pre-B-cell receptor (pre-BCR) is thought to signal transcriptional activation of the immunoglobulin light (L) chain gene locus, proceeding to its V-J rearrangement. The pre-BCR signaling pathway for this process is largely unknown but may involve the adaptor protein BASH (BLNK/SLP-65). Here we report that the pre-B leukemia cell lines established from affected BASH-deficient mice rearrange kappaL-chain gene locus and down-regulate pre-BCR upon PMA treatment or BASH reconstitution. Analyses with specific inhibitors revealed that activation of novel PKC (nPKC) and MEK, but not Ras, is necessary for the rearrangement. Accordingly, retroviral transduction of active PKCeta, PKCepsilon, or Raf-1, but not Ras, induced the kappa gene rearrangement and expression in the pre-B-cell line. Tamoxifen-mediated BASH reconstitution resulted in the translocation of PKCeta to the plasma membrane and kappa chain expression. These data make evident that the Ras-independent BASH-nPKC-Raf-1 pathway of pre-BCR signaling induces the L-chain gene rearrangement and expression.
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MESH Headings
- Adaptor Proteins, Signal Transducing/deficiency
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/metabolism
- Animals
- Base Sequence
- Cell Differentiation
- Cell Line, Tumor
- DNA, Neoplasm/genetics
- Gene Rearrangement, B-Lymphocyte, Light Chain
- Leukemia, B-Cell/genetics
- Leukemia, B-Cell/immunology
- Leukemia, B-Cell/metabolism
- Mice
- Mice, Knockout
- Mitogen-Activated Protein Kinase Kinases/metabolism
- Preleukemia/genetics
- Preleukemia/immunology
- Preleukemia/metabolism
- Protein Kinase C/metabolism
- Proto-Oncogene Proteins c-raf/metabolism
- Signal Transduction
- ras Proteins/metabolism
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Affiliation(s)
- Mutsumi Yamamoto
- Division of Molecular Biology, Research Institute for Biological Sciences, Tokyo University of Science, Yamazaki 2669, Noda, Chiba 278-0022, Japan
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74
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Abstract
Alternative pre-mRNA splicing leads to distinct products of gene expression in development and disease. Antagonistic splice variants of genes involved in differentiation, apoptosis, invasion and metastasis often exist in a delicate equilibrium that is found to be perturbed in tumours. In several recent examples, splice variants that are overexpressed in cancer are expressed as hyper-oncogenic proteins, which often correlate with poor prognosis, thus suggesting improved diagnosis and follow up treatment. Global gene expression technologies are just beginning to decipher the interplay between alternatively spliced isoforms and protein-splicing factors that will lead to identification of the mutations in these trans-acting factors responsible for pathogenic alternative splicing in cancer.
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Affiliation(s)
- Julian P Venables
- University of Newcastle-upon-Tyne, Institute of Human Genetics, International Centre for Life, Central Parkway, Newcastle-upon-Tyne, UK.
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75
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Sprangers M, Feldhahn N, Liedtke S, Jumaa H, Siebert R, Müschen M. SLP65 deficiency results in perpetual V(D)J recombinase activity in pre-B-lymphoblastic leukemia and B-cell lymphoma cells. Oncogene 2006; 25:5180-6. [PMID: 16636677 DOI: 10.1038/sj.onc.1209520] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Perpetual V(D)J recombinase activity involving multiple DNA double-strand break events in B-cell lineage leukemia and lymphoma cells may introduce secondary genetic aberrations leading towards malignant progression. Here, we investigated defective negative feedback signaling through the (pre-) B-cell receptor as a possible reason for deregulated V(D)J recombinase activity in B-cell malignancy. On studying 28 cases of pre-B-lymphoblastic leukemia and 27 B-cell lymphomas, expression of the (pre-) B-cell receptor-related linker molecule SLP65 (SH2 domain-containing lymphocyte protein of 65 kDa) was found to be defective in seven and five cases, respectively. SLP65 deficiency correlates with RAG1/2 expression and unremitting V(H) gene rearrangement activity. Reconstitution of SLP65 expression in SLP65-deficient leukemia and lymphoma cells results in downregulation of RAG1/2 expression and prevents both de novo V(H)-DJ(H) rearrangements and secondary V(H) replacement. We conclude that iterative V(H) gene rearrangement represents a frequent feature in B-lymphoid malignancy, which can be attributed to SLP65 deficiency in many cases.
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Affiliation(s)
- M Sprangers
- Laboratory for Molecular Stem Cell Biology, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
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76
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Klein F, Feldhahn N, Herzog S, Sprangers M, Mooster JL, Jumaa H, Müschen M. BCR-ABL1 induces aberrant splicing of IKAROS and lineage infidelity in pre-B lymphoblastic leukemia cells. Oncogene 2006; 25:1118-24. [PMID: 16205638 DOI: 10.1038/sj.onc.1209133] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Pre-B lymphoblastic leukemia cells carrying a BCR-ABL1 gene rearrangement exhibit an undifferentiated phenotype. Comparing the genome-wide gene expression profiles of normal B-cell subsets and BCR-ABL1+ pre-B lymphoblastic leukemia cells by SAGE, the leukemia cells show loss of B lymphoid identity and aberrant expression of myeloid lineage-specific molecules. Consistent with this, BCR-ABL1+ pre-B lymphoblastic leukemia cells exhibit defective expression of IKAROS, a transcription factor needed for early lymphoid lineage commitment. As shown by inducible expression of BCR-ABL1 in human and murine B-cell precursor cell lines, BCR-ABL1 induces the expression of a dominant-negative IKAROS splice variant, termed IK6. Comparing matched leukemia sample pairs from patients before and during therapy with the BCR-ABL1 kinase inhibitor STI571 (Imatinib), inhibition of BCR-ABL1 partially corrected aberrant expression of IK6 and lineage infidelity of the leukemia cells. To elucidate the contribution of IK6 to lineage infidelity in BCR-ABL1+ cell lines, IK6 expression was silenced by RNA interference. Upon inhibition of IK6, BCR-ABL1+ leukemia cells partially restored B lymphoid lineage commitment. Therefore, we propose that BCR-ABL1 induces aberrant splicing of IKAROS, which interferes with lineage identity and differentiation of pre-B lymphoblastic leukemia cells.
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Affiliation(s)
- F Klein
- Laboratory for Molecular Stem Cell Biology, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
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77
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Sprangers M, Feldhahn N, Herzog S, Hansmann ML, Reppel M, Hescheler J, Jumaa H, Siebert R, Müschen M. The SRC family kinase LYN redirects B cell receptor signaling in human SLP65-deficient B cell lymphoma cells. Oncogene 2006; 25:5056-62. [PMID: 16568084 DOI: 10.1038/sj.onc.1209510] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
SLP65 represents a critical component in (pre-) B cell receptor signal transduction but is compromised in a subset of pre-B cell-derived acute lymphoblastic leukemia. Based on these findings, we investigated (i.) whether SLP65-deficiency also occurs in mature B cell-derived lymphoma and (ii.) whether SLP65-deficient B cell lymphoma cells use an alternative B cell receptor signaling pathway in the absence of SLP65. Indeed, expression of SLP65 protein was also missing in a fraction of B cell lymphoma cases. While SLP65 is essential for B cell receptor-induced Ca2+ mobilization in normal B cells, B cell receptor engagement in SLP65-deficient as compared to SLP65-reconstituted B cell lymphoma cells resulted in an accelerated yet shortlived Ca2+-signal. B cell receptor engagement of SLP65-deficient lymphoma cells involves SRC kinase activation, which is critical for B cell receptor-dependent Ca2+-mobilisation in the absence but not in the presence of SLP65. As shown by RNA interference, the SRC kinase LYN is required for B cell receptor-induced Ca2+ release in SLP65-deficient B cell lymphoma cells but dispensable after SLP65-reconstitution. B cell receptor engagement in SLP65-deficient B cell lymphoma cells also resulted in tyrosine-phosphorylation of the proliferation- and survival-related MAPK1 and STAT5 molecules, which was sensitive to silencing of the SRC kinase LYN. Inhibition of SRC kinase activity resulted in growth arrest and cell death specifically in SLP65-deficient lymphoma cells. These findings indicate that LYN can short-circuit conventional B cell receptor signaling in SLP65-deficient B cell lymphoma cells and thereby promote activation of survival and proliferation-related molecules.
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Affiliation(s)
- M Sprangers
- Laboratory for Molecular Stem Cell Biology, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, and Institute of Human Genetics, University Hospital Schleswig-Holstein Campus Kiel, Germany
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78
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Koretzky GA, Abtahian F, Silverman MA. SLP76 and SLP65: complex regulation of signalling in lymphocytes and beyond. Nat Rev Immunol 2006; 6:67-78. [PMID: 16493428 DOI: 10.1038/nri1750] [Citation(s) in RCA: 205] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
SLP76 and SLP65 are adaptor proteins that lack intrinsic enzymatic activity but contain multiple protein-binding domains. These proteins are essential for signalling downstream of integrins and receptors that contain immunoreceptor tyrosine-based activation motifs. The absence of these adaptor proteins profoundly affects various lineages in the haematopoietic compartment and severely compromises vascular development, highlighting their importance as regulators of signalling cascades. In this Review, we discuss the role of SLP76 and SLP65 in several signalling pathways in haematopoietic cells, with an emphasis on recent studies that provide insight into their mechanisms of action.
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Affiliation(s)
- Gary A Koretzky
- Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, University of Pennsylvania, 415 BRBII/III, 421 Curie Boulevard, Philadelphia, Pennsylvania 19104, USA.
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79
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Nakagawa R, Soh JW, Michie AM. Subversion of protein kinase C alpha signaling in hematopoietic progenitor cells results in the generation of a B-cell chronic lymphocytic leukemia-like population in vivo. Cancer Res 2006; 66:527-34. [PMID: 16397269 DOI: 10.1158/0008-5472.can-05-0841] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
B-cell chronic lymphocytic leukemia (B-CLL) is characterized by the accumulation of long-lived mature B cells with the distinctive phenotype CD19(hi) CD5+ CD23+ IgM(lo), which are refractory to apoptosis. An increased level of apoptosis has been observed on treatment of human B-CLL cells with protein kinase C (PKC) inhibitors, suggesting that this family of protein kinases mediate survival signals within B-CLL cells. Therefore, to investigate the ability of individual PKC isoforms to transform developing B cells, we stably expressed plasmids encoding PKC mutants in fetal liver-derived hematopoietic progenitor cells (HPC) from wild-type mice and then cultured them in B-cell generation systems in vitro and in vivo. Surprisingly, we noted that expression of a plasmid-encoding dominant-negative PKC alpha (PKC alpha-KR) in HPCs and subsequent culture both in vitro and in vivo resulted in the generation of a population of cells that displayed an enhanced proliferative capacity over untransfected cells and phenotypically resemble human B-CLL cells. In the absence of growth factors and stroma, these B-CLL-like cells undergo cell cycle arrest and, consistent with their ability to escape growth factor withdrawal-induced apoptosis, exhibited elevated levels of Bcl-2 expression. These studies therefore identify a unique oncogenic trigger for the development of a B-CLL-like disease resulting from the subversion of PKC alpha signaling. Our findings uncover novel avenues not only for the study of the induction of leukemic B cells but also for the development of therapeutic drugs to combat PKC alpha-regulated transformation events.
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Affiliation(s)
- Rinako Nakagawa
- Division of Immunology, Infection and Inflammation, Western Infirmary, University of Glasgow, Scotland, United Kingdom
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80
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Vettermann C, Herrmann K, Jäck HM. Powered by pairing: The surrogate light chain amplifies immunoglobulin heavy chain signaling and pre-selects the antibody repertoire. Semin Immunol 2006; 18:44-55. [PMID: 16464608 DOI: 10.1016/j.smim.2006.01.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Selective expansion of functional pre-B cells is accomplished by the assembly of a signaling-competent pre-B cell receptor (pre-BCR) consisting of immunoglobulin mu heavy chains (muHC), surrogate light chains (SLC) and Igalpha/Igbeta. Here, we review recent data showing that muHCs, in the absence of SLC, deliver autonomous differentiation signals. However, enhanced signaling necessary for pre-B cell expansion requires cross-linking of pre-BCRs via the non-immunoglobulin tail of SLC's subunit lambda5. We also discuss how SLC's ability to modulate the strength of pre-BCR signals is controlled by a muHC's idiotype and its affinity to the chaperone BiP. In this model, BiP in concert with SLC functions as a pre-selector of the antibody repertoire.
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Affiliation(s)
- Christian Vettermann
- Division of Molecular Immunology, Department of Internal Medicine III, Nikolaus-Fiebiger-Center for Molecular Medicine, Friedrich-Alexander-University Erlangen-Nürnberg, D-91054 Erlangen, Germany
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81
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Hendriks RW, Kersseboom R. Involvement of SLP-65 and Btk in tumor suppression and malignant transformation of pre-B cells. Semin Immunol 2006; 18:67-76. [PMID: 16300960 DOI: 10.1016/j.smim.2005.10.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Signals from the precursor-B cell receptor (pre-BCR) are essential for selection and clonal expansion of pre-B cells that have performed productive immunoglobulin heavy chain V(D)J recombination. In the mouse, the downstream signaling molecules SLP-65 and Btk cooperate to limit proliferation and induce differentiation of pre-B cells, thereby acting as tumor suppressors to prevent pre-B cell leukemia. In contrast, recent observations in human BCR-ABL1(+) pre-B lymphoblastic leukemia cells demonstrate that Btk is constitutively phosphorylated and activated by the BCR-ABL1 fusion protein. As a result, activated Btk transmits survival signals that are essential for the transforming activity of oncogenic Abl tyrosine kinase.
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Affiliation(s)
- Rudi W Hendriks
- Department of Immunology, Erasmus MC Rotterdam, P.O. Box 1738, NL-3000 DR Rotterdam, The Netherlands.
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82
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Melchers F. B cell development and its deregulation to transformed states at the pre-B cell receptor-expressing pre-BII cell stage. Curr Top Microbiol Immunol 2005; 294:1-17. [PMID: 16323425 DOI: 10.1007/3-540-29933-5_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
This chapter will review the scenario of normal B cell development--from the decision of a lymphoid progenitor to enter the B-lineage, over the stages of the generation of the repertoires of antigen-receptor (immunoglobulin)-expressing cells, to the response of mature B cells to develop memory and plasma cells--highlighting some of the cellular stages and the molecular mechanisms that can generate and select transformed states of cells. The scenarios for pre-B lymphoma (lymphocytic leukaemia) development are discussed in more detail.
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MESH Headings
- Animals
- Apoptosis
- B-Lymphocytes/cytology
- B-Lymphocytes/immunology
- Cell Differentiation
- Cell Proliferation
- Cell Transformation, Neoplastic
- Gene Rearrangement, B-Lymphocyte
- Humans
- Interleukin-7/metabolism
- Lymphoma, B-Cell/etiology
- Lymphoma, B-Cell/genetics
- Lymphoma, B-Cell/immunology
- Mice
- Mutation
- PAX5 Transcription Factor/metabolism
- Receptors, Antigen, B-Cell/genetics
- Receptors, Antigen, B-Cell/metabolism
- Receptors, Interleukin-7/metabolism
- Signal Transduction
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Affiliation(s)
- F Melchers
- Department of Cell Biology, Biozentrum of the University of Basel, Switzerland.
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83
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Parker MJ, Licence S, Erlandsson L, Galler GR, Chakalova L, Osborne CS, Morgan G, Fraser P, Jumaa H, Winkler TH, Skok J, Mårtensson IL. The pre-B-cell receptor induces silencing of VpreB and lambda5 transcription. EMBO J 2005; 24:3895-905. [PMID: 16281060 PMCID: PMC1283949 DOI: 10.1038/sj.emboj.7600850] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2005] [Accepted: 10/06/2005] [Indexed: 01/17/2023] Open
Abstract
The pre-B-cell receptor (pre-BCR), composed of Ig heavy and surrogate light chain (SLC), signals pre-BII-cell proliferative expansion. We have investigated whether the pre-BCR also signals downregulation of the SLC genes (VpreB and lambda5), thereby limiting this expansion. We demonstrate that, as BM cells progress from the pre-BI to large pre-BII-cell stage, there is a shift from bi- to mono-allelic lambda5 transcription, while the second allele is silenced in small pre-BII cells. A VpreB1-promoter-driven transgene shows the same pattern, therefore suggesting that VpreB1 is similarly regulated and thereby defines the promoter as a target for transcriptional silencing. Analyses of pre-BCR-deficient mice show a temporal delay in lambda5 downregulation, thereby demonstrating that the pre-BCR is essential for monoallelic silencing at the large pre-BII-cell stage. Our data also suggest that SLP-65 is one of the signaling components important for this process. Furthermore, the VpreB1/lambda5 alleles undergo dynamic changes with respect to nuclear positioning and heterochromatin association, thereby providing a possible mechanism for their transcriptional silencing.
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Affiliation(s)
- Mathew J Parker
- Laboratory of Lymphocyte Signaling and Development, The Babraham Institute, Cambridge, UK
| | - Steve Licence
- Laboratory of Lymphocyte Signaling and Development, The Babraham Institute, Cambridge, UK
| | - Lena Erlandsson
- Laboratory of Lymphocyte Signaling and Development, The Babraham Institute, Cambridge, UK
| | | | - Lyubomira Chakalova
- Laboratory of Chromatin and Gene Expression, The Babraham Institute, Cambridge, UK
| | - Cameron S Osborne
- Laboratory of Chromatin and Gene Expression, The Babraham Institute, Cambridge, UK
| | - Geoff Morgan
- Flow Cytometry Facility, The Babraham Institute, Cambridge, UK
| | - Peter Fraser
- Laboratory of Chromatin and Gene Expression, The Babraham Institute, Cambridge, UK
| | - Hassan Jumaa
- Institute for Biology III, Max-Planck-Institute for Immunobiology, Freiburg, Germany
| | | | - Jane Skok
- Department of Immunology and Molecular Pathology, UCL, London, UK
| | - Inga-Lill Mårtensson
- Laboratory of Lymphocyte Signaling and Development, The Babraham Institute, Cambridge, UK
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84
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Feldhahn N, Río P, Soh BNB, Liedtke S, Sprangers M, Klein F, Wernet P, Jumaa H, Hofmann WK, Hanenberg H, Rowley JD, Müschen M. Deficiency of Bruton's tyrosine kinase in B cell precursor leukemia cells. Proc Natl Acad Sci U S A 2005; 102:13266-71. [PMID: 16141323 PMCID: PMC1201599 DOI: 10.1073/pnas.0505196102] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bruton's tyrosine kinase (BTK) deficiency results in a differentiation block at the pre-B cell stage. Likewise, acute lymphoblastic leukemia cells are typically arrested at early stages of B cell development. We therefore investigated BTK function in B cell precursor leukemia cells carrying a BCR-ABL1, E2A-PBX1, MLL-AF4, TEL-AML1, or TEL-PDGFRB gene rearrangement. Although somatic mutations of the BTK gene are rare in B cell precursor leukemia cells, we identified kinase-deficient splice variants of BTK throughout all leukemia subtypes. Unlike infant leukemia cells carrying an MLL-AF4 gene rearrangement, where expression of full-length BTK was detectable in only four of eight primary cases, in leukemia cells harboring other fusion genes full-length BTK was typically coexpressed with kinase-deficient variants. As shown by overexpression experiments, kinase-deficient splice variants can act as a dominant-negative BTK in that they suppress BTK-dependent differentiation and pre-B cell receptor responsiveness of the leukemia cells. On the other hand, induced expression of full-length BTK rendered the leukemia cells particularly sensitive to apoptosis. Comparing BTK expression in surviving or preapoptotic leukemia cells after 10-Gy gamma radiation, we observed selective survival of leukemia cells that exhibit expression of dominant-negative BTK forms. These findings indicate that lack of BTK expression or expression of dominant-negative splice variants in B cell precursor leukemia cells can (i) inhibit differentiation beyond the pre-B cell stage and (ii) protect from radiation-induced apoptosis.
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Affiliation(s)
- Niklas Feldhahn
- Laboratory for Molecular Stem Cell Biology, Institute for Transplantation Diagnostics and Cell Therapeutics, and Department of Pediatric Hematology and Oncology, Children's Hospital, Heinrich-Heine-Universität, 40225 Düsseldorf, Germany
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85
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Melchers F. The pre-B-cell receptor: selector of fitting immunoglobulin heavy chains for the B-cell repertoire. Nat Rev Immunol 2005; 5:578-84. [PMID: 15999097 DOI: 10.1038/nri1649] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In this Opinion article, I address the role of the pre-B-cell receptor (pre-BCR) in the development of antigen-specific B cells in terms of immunoglobulin heavy chain (IgH) variable-region repertoire selection, precursor B-cell differentiation and proliferation, and IgH allelic exclusion. Comparisons with the role of the pre-T-cell receptor (pre-TCR) in T-cell development raise provocative questions. Why do B- and T-cell lineages both use a surrogate chain - the surrogate light chain and the pre-TCR alpha-chain, respectively - as a step to develop their repertoires of antigen-recognizing cells? What are the functions of the pre-BCR and pre-TCR in lymphocyte differentiation and antigen-receptor allelic exclusion? This article, together with the accompanying article by Harald von Boehmer, hopes to answer some of these questions.
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Affiliation(s)
- Fritz Melchers
- Max Planck Institute for Infection Biology, Campus Charité Mitte, Schumannstrasse 21-22, D-10117 Berlin, Germany.
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86
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Abstract
The proliferation and differentiation of lymphocytes are regulated by receptors localized on the cell surface. Engagement of these receptors induces the activation of intracellular signaling proteins that transmit the receptor signals to distinct targets and control the cellular responses. The first signaling proteins to be discovered in higher organisms were the products of oncogenes. For example, the kinases Src and Abelson (Abl) were originally identified as oncogenes and were later characterized as important proteins for signal transduction in various cell types, including lymphocytes. Now, as many cellular signaling molecules have been discovered and ordered into certain pathways, we can better understand why particular signaling proteins are associated with tumorigenesis. In this review, we discuss recent progress in unraveling the molecular mechanisms of signaling pathways that control the proliferation and differentiation of early B cells. We point out the concepts of auto-inhibition and subcellular localization as crucial aspects in the regulation of B cell signaling.
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Affiliation(s)
- Hassan Jumaa
- Institute for Biology III, Albert-Ludwigs University of Freiburg and Max Planck Institute for Immunobiology, 79108 Freiburg, Germany.
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87
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Abstract
Adapter molecules are multidomain proteins lacking intrinsic catalytic activity, functioning instead by nucleating molecular complexes during signal transduction. The SLP-76 family of adapters includes SH2 domain-containing leukocyte phosphoprotein of 76kDa (SLP-76), B cell linker protein (BLNK), and cytokine-dependent hematopoietic cell linker (Clnk). These proteins are critical for integration of numerous signaling cascades downstream of immunotyrosine-based activation motif (ITAM)-bearing receptors and integrins in diverse hematopoietic cell types. Mutations in genes encoding SLP-76 family adapters result in severe phenotypes, underscoring the critical role these proteins play in cellular development and function by directing formation of signaling complexes in a temporally- and spatially-specific manner.
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Affiliation(s)
- Jennifer N Wu
- Department of Laboratory Medicine and Pathology, School of Medicine, Abramson Family Cancer Research Institute, University of Pennsylvania, 415 BRB II/III, 421 Curie Boulevard, Philadelphia, PA 19104, USA
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88
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Su YW, Herzog S, Lotz M, Feldhahn N, Müschen M, Jumaa H. The molecular requirements for LAT-mediated differentiation and the role of LAT in limiting pre-B cell expansion. Eur J Immunol 2005; 34:3614-22. [PMID: 15549729 DOI: 10.1002/eji.200425445] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Successful recombination of the heavy-chain locus in developing B cells results in the expression of the pre-BCR, which induces the proliferation and expansion of pre-B cells. To avoid uncontrolled proliferation, pre-BCR signals transmitted via the adaptor protein SLP-65 (SH2-domain-containing leukocyte protein of 65 kDa) lead to the down-regulation of pre-BCR expression and to pre-B cell differentiation. Here, we show that, similarly to SLP-65, the adaptor protein LAT (linker for activation of T cells) limits pre-B cell proliferation and reduces the potential of a tumorgenic pre-B cell line to develop leukemia in immune-deficient mice. We further show that the four distal tyrosines are required for LAT activity in pre-B cells. Mutation at Y136 completely abolishes LAT activity, whereas single point-mutations at Y175, Y195 or Y235 impair, but do not block, LAT-induced pre-B cell differentiation. As LAT is also expressed in human pre-B cells, our results suggest that LAT cooperates with SLP-65 to promote the differentiation and control the proliferation of both murine and human pre-B cells.
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Affiliation(s)
- Yu-Wen Su
- Institute for Biology III, Albert-Ludwigs University of Freiburg and Max Planck Institute for Immunobiology, Freiburg, Germany
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89
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Köhler F, Storch B, Kulathu Y, Herzog S, Kuppig S, Reth M, Jumaa H. A leucine zipper in the N terminus confers membrane association to SLP-65. Nat Immunol 2005; 6:204-10. [PMID: 15654340 DOI: 10.1038/ni1163] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2004] [Accepted: 12/22/2004] [Indexed: 11/09/2022]
Abstract
Membrane recruitment of adaptor proteins is crucial for coupling antigen receptors to downstream signaling events. Despite the essential function of the B cell adaptor SLP-65, the mechanism of its recruitment to the plasma membrane is not yet understood. Here we show that a highly conserved leucine zipper in the SLP-65 N terminus is responsible for membrane association. Alterations in the N terminus abolished SLP-65 membrane localization and activity, both of which were restored by replacement of the N terminus with a myristoylation signal. The N terminus is an autonomous domain that confers specific localization and function when transferred to green fluorescent protein or the adaptor protein SLP-76. Our data elucidate the mechanism of SLP-65 membrane recruitment and suggest that leucine zipper motifs are essential interaction domains of signaling proteins.
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Affiliation(s)
- Fabian Köhler
- Institute for Biology III, Albert-Ludwigs University of Freiburg and Max-Planck-Institute for Immunobiology, Stuebeweg 51, 79108 Freiburg, Germany
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90
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91
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Taguchi T, Kiyokawa N, Takenouch H, Matsui J, Tang WR, Nakajima H, Suzuki K, Shiozawa Y, Saito M, Katagiri YU, Takahashi T, Karasuyama H, Matsuo Y, Okita H, Fujimoto J. Deficiency of BLNK hampers PLC-gamma2 phosphorylation and Ca2+ influx induced by the pre-B-cell receptor in human pre-B cells. Immunology 2004; 112:575-82. [PMID: 15270728 PMCID: PMC1782531 DOI: 10.1111/j.1365-2567.2004.01918.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
B-cell linker protein (BLNK) is a component of the B-cell receptor (BCR) as well as of the pre-BCR signalling pathway, and BLNK(-/-) mice have a block in B lymphopoiesis at the pro-B/pre-B cell stage. A recent report described the complete loss or drastic reduction of BLNK expression in approximately 50% of human childhood pre-B acute lymphoblastic leukaemias (ALL), therefore we investigated BLNK expression in human pre-B ALL cell lines. One of the four cell lines tested, HPB-NULL cells, was found to lack BLNK expression, and we used these human pre-B ALL cell lines that express and do not express BLNK to investigate the intracellular signalling events following pre-BCR cross-linking. When pre-BCR was cross-linked with anti-micro heavy-chain antibodies, significant phosphorylation of intracellular molecules, including Syk, Shc, ERK MAP kinase, and AKT, and an activation of Ras were observed without regard to deficiency of BLNK expression, suggesting that BLNK is not required for pre-BCR-mediated activation of MAP kinase and phosphatidyl-inositol 3 (PI3) kinase signalling. By contrast, phospholipase C-gamma2 (PLC-gamma2) phosphorylation and an increase in intracellular Ca(2+) level mediated by pre-BCR cross-linking were observed only in the BLNK-expressing cells, indicating that BLNK is essential for PLC-gamma2-induced Ca(2+) influx. Human pre-B cell lines expressing and not expressing BLNK should provide an in vitro model for investigation of the role of BLNK in the pre-BCR-mediated signalling mechanism.
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Affiliation(s)
- Tomoko Taguchi
- Department of Developmental Biology, National Research Institute for Child Health and DevelopmentSetagaya-ku, Tokyo
- Department of Pediatrics, Keio University, School of MedicineShinjuku-ku, Tokyo
| | - Nobutaka Kiyokawa
- Department of Developmental Biology, National Research Institute for Child Health and DevelopmentSetagaya-ku, Tokyo
| | - Hisami Takenouch
- Department of Developmental Biology, National Research Institute for Child Health and DevelopmentSetagaya-ku, Tokyo
| | - Jun Matsui
- Department of Developmental Biology, National Research Institute for Child Health and DevelopmentSetagaya-ku, Tokyo
| | - Wei-Ran Tang
- Department of Developmental Biology, National Research Institute for Child Health and DevelopmentSetagaya-ku, Tokyo
| | - Hideki Nakajima
- Department of Developmental Biology, National Research Institute for Child Health and DevelopmentSetagaya-ku, Tokyo
| | - Kyoko Suzuki
- Department of Developmental Biology, National Research Institute for Child Health and DevelopmentSetagaya-ku, Tokyo
| | - Yusuke Shiozawa
- Department of Developmental Biology, National Research Institute for Child Health and DevelopmentSetagaya-ku, Tokyo
| | - Masahiro Saito
- Department of Developmental Biology, National Research Institute for Child Health and DevelopmentSetagaya-ku, Tokyo
| | - Yohko U Katagiri
- Department of Developmental Biology, National Research Institute for Child Health and DevelopmentSetagaya-ku, Tokyo
| | - Takao Takahashi
- Department of Pediatrics, Keio University, School of MedicineShinjuku-ku, Tokyo
| | - Hajime Karasuyama
- Department of Immune Regulation, Tokyo Medical and Dental University, Graduate SchoolTokyo
| | - Yoshinobu Matsuo
- Fujisaki Cell Center, Hayashibara Biochemical Laboratories IncFujisaki, Okayama, Japan
| | - Hajime Okita
- Department of Developmental Biology, National Research Institute for Child Health and DevelopmentSetagaya-ku, Tokyo
| | - Junichiro Fujimoto
- Department of Developmental Biology, National Research Institute for Child Health and DevelopmentSetagaya-ku, Tokyo
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92
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Klein F, Feldhahn N, Harder L, Wang H, Wartenberg M, Hofmann WK, Wernet P, Siebert R, Müschen M. The BCR-ABL1 kinase bypasses selection for the expression of a pre-B cell receptor in pre-B acute lymphoblastic leukemia cells. ACTA ACUST UNITED AC 2004; 199:673-85. [PMID: 14993251 PMCID: PMC2213306 DOI: 10.1084/jem.20031637] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The BCR-ABL1 kinase expressed in acute lymphoblastic leukemia (ALL) drives malignant transformation of human pre–B cells. Comparing genome-wide gene expression profiles of BCR-ABL1+ pre–B ALL and normal bone marrow pre–B cells by serial analysis of gene expression, many genes involved in pre–B cell receptor signaling are silenced in the leukemia cells. Although normal pre–B cells are selected for the expression of a functional pre–B cell receptor, BCR-ABL1+ ALL cells mostly do not harbor a productively rearranged IGH allele. In these cases, we identified traces of secondary VH gene rearrangements, which may have rendered an initially productive VH region gene nonfunctional. Even BCR-ABL1+ ALL cells harboring a functional VH region gene are unresponsive to pre–B cell receptor engagement and exhibit autonomous oscillatory Ca2+ signaling activity. Conversely, leukemia subclones surviving inhibition of BCR-ABL1 by STI571 restore responsiveness to antigen receptor engagement and differentiate into immature B cells expressing immunoglobulin light chains. BCR-ABL1 kinase activity is linked to defective pre–B cell receptor signaling and the expression of a truncated isoform of the pre–B cell receptor–associated linker molecule SLP65. Also in primary leukemia cells, truncated SLP65 is expressed before but not after treatment of the patients with STI571. We conclude that inhibition of BCR-ABL1 reconstitutes selection for leukemia cells expressing a functional (pre–) B cell receptor.
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Affiliation(s)
- Florian Klein
- Laboratory for Molecular Stem Cell Biology, Institute for Transplantation Diagnostics and Cell Therapeutics, Heinrich-Heine-Universität Düsseldorf, 40225, Germany
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93
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Middendorp S, Zijlstra AJE, Kersseboom R, Dingjan GM, Jumaa H, Hendriks RW. Tumor suppressor function of Bruton tyrosine kinase is independent of its catalytic activity. Blood 2004; 105:259-65. [PMID: 15331445 DOI: 10.1182/blood-2004-07-2708] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During B-cell development in the mouse, Bruton tyrosine kinase (Btk) and the adaptor protein SLP-65 (Src homology 2 [SH2] domain-containing leukocyte protein of 65 kDa) limit the expansion and promote the differentiation of pre-B cells. Btk is thought to mainly function by phosphorylating phospholipase Cgamma2, which is brought into close proximity of Btk by SLP-65. However, this model was recently challenged by the identification of a role for Btk as a tumor suppressor in the absence of SLP-65 and by the finding that Btk function is partially independent of its kinase activity. To investigate if enzymatic activity is critical for the tumor suppressor function of Btk, we crossed transgenic mice expressing the kinase-inactive K430R-Btk mutant onto a Btk/SLP-65 double-deficient background. We found that K430R-Btk expression rescued the severe developmental arrest at the pre-B-cell stage in Btk/SLP-65 double-deficient mice. Moreover, K430R-Btk could functionally replace wild-type Btk as a tumor suppressor in SLP-65- mice: at 6 months of age, the observed pre-B-cell lymphoma frequencies were approximately 15% for SLP-65- mice, 44% for Btk/SLP-65-deficient mice, and 14% for K430R-Btk transgenic mice on the Btk/SLP-65-deficient background. Therefore, we conclude that Btk exerts its tumor suppressor function in pre-B cells as an adaptor protein, independent of its catalytic activity.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Agammaglobulinaemia Tyrosine Kinase
- Animals
- B-Lymphocytes/immunology
- B-Lymphocytes/metabolism
- B-Lymphocytes/pathology
- Calcium/metabolism
- Calcium Signaling
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Catalysis
- Cell Differentiation
- Cells, Cultured
- Immunoglobulin G/blood
- Immunoglobulin G/immunology
- Lymphoma, B-Cell/enzymology
- Lymphoma, B-Cell/genetics
- Lymphoma, B-Cell/metabolism
- Lymphoma, B-Cell/pathology
- Lysine/genetics
- Lysine/metabolism
- Mice
- Mice, Knockout
- Mice, Transgenic
- Phosphoproteins/deficiency
- Phosphoproteins/genetics
- Phosphoproteins/metabolism
- Phosphotyrosine/metabolism
- Protein-Tyrosine Kinases/deficiency
- Protein-Tyrosine Kinases/genetics
- Protein-Tyrosine Kinases/metabolism
- Receptors, Antigen, B-Cell/metabolism
- Survival Rate
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Affiliation(s)
- Sabine Middendorp
- Department of Immunology, Erasmus MC Rotterdam, Rotterdam, The Netherlands
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94
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Hendriks RW, Middendorp S. The pre-BCR checkpoint as a cell-autonomous proliferation switch. Trends Immunol 2004; 25:249-56. [PMID: 15099565 DOI: 10.1016/j.it.2004.02.011] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
MESH Headings
- Adaptor Proteins, Signal Transducing
- Agammaglobulinaemia Tyrosine Kinase
- Amino Acid Motifs
- Animals
- B-Lymphocytes/cytology
- B-Lymphocytes/immunology
- Carrier Proteins/physiology
- Cell Division/physiology
- Genes, Immunoglobulin
- Humans
- Immunoglobulin Switch Region
- Lymphocyte Activation
- Lymphoma, B-Cell/immunology
- Lymphoma, B-Cell/pathology
- Mice
- Mice, Knockout
- Models, Immunological
- Multienzyme Complexes/physiology
- Phosphoproteins/deficiency
- Phosphoproteins/physiology
- Phosphorylation
- Precursor B-Cell Lymphoblastic Leukemia-Lymphoma/immunology
- Precursor B-Cell Lymphoblastic Leukemia-Lymphoma/pathology
- Protein Processing, Post-Translational
- Protein-Tyrosine Kinases/physiology
- Receptors, Antigen, B-Cell/immunology
- Receptors, Interleukin-7/physiology
- Signal Transduction
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Affiliation(s)
- Rudi W Hendriks
- Department of Immunology, Erasmus MC Rotterdam, PO Box 1738, NL-3000 DR Rotterdam, The Netherlands.
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95
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Imamura Y, Katahira T, Kitamura D. Identification and characterization of a novel BASH N terminus-associated protein, BNAS2. J Biol Chem 2004; 279:26425-32. [PMID: 15087455 DOI: 10.1074/jbc.m403685200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A B cell-specific adaptor protein, BASH (also known as BLNK or SLP-65), is crucial for B cell receptor (BCR) signaling. BASH binds to various signaling intermediates, such as Btk, PLCgamma2, Vav, and Grb2, through its well defined motifs. Although functional significance of such interactions has been documented, BASH-mediated signal transduction mechanism is not fully understood. Using the yeast two-hybrid system, we have identified a novel protein that binds to a conserved N-terminal domain of BASH, which we named BNAS2 (BASH N terminus associated protein 2). From its deduced amino acid sequence, BNAS2 is presumed to contain four transmembrane domains, which are included in a central MARVEL domain, and to localize to endoplasmic reticulum. BNAS2 was co-precipitated with BASH as well as Btk and ERK2 from a lysate of mouse B cell line. In the transfected cells, the exogenous BNAS2 was localized in a mesh-like structure in the cytoplasm resembling that of endoplasmic reticulum (ER) and nuclear membrane. BASH was co-localized with BNAS2 in a manner dependent on its N-terminal domain. RT-PCR analysis indicated that BNAS2 mRNA is expressed ubiquitously except for plasma cells. In chicken B cell line DT40, overexpression of BNAS2 resulted in an enhancement of BCR ligation-mediated transcriptional activation of Elk1, but not of NF-kappaB, in a manner dependent on the dose of BNAS2. Thus BNAS2 may serve as a scaffold for signaling proteins such as BASH, Btk, and ERK at the ER and nuclear membrane and may facilitate ERK activation by signaling from cell-surface receptors.
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Affiliation(s)
- Yasuhiro Imamura
- Research Institute for Biological Sciences, Tokyo University of Science, 2669 Yamazaki, Noda-city, Chiba 278-0022, Japan
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96
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Imai C, Ross ME, Reid G, Coustan-Smith E, Schultz KR, Pui CH, Downing JR, Campana D. Expression of the adaptor protein BLNK/SLP-65 in childhood acute lymphoblastic leukemia. Leukemia 2004; 18:922-5. [PMID: 15029213 DOI: 10.1038/sj.leu.2403349] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Deficient expression of BLNK, an adaptor molecule crucial for normal B-cell development, is associated with increased pro-B/pre-B-cell expansion in mice. It has been proposed that BLNK deficiency is a primary cause of B-lineage acute lymphoblastic leukemia (ALL). We studied BLNK expression in the leukemic cells from 352 patients with childhood ALL (309 B-lineage; 43 T-lineage). By HG_U95Av2 Affymetrix GeneChip analysis, BLNK was expressed in 275 of 284 (96.8%) B-lineage ALL samples but in only one of 43 (2.3%) T-lineage ALL samples. Of 118 B-lineage ALL samples analyzed with the HG_U133A GeneChip, 117 (99.2%) expressed BLNK. All 30 primary B-lineage ALL samples studied by RT-PCR expressed BLNK transcripts; all 19 samples studied by Western blotting or flow cytometry expressed BLNK protein. Levels of BLNK in B-lineage ALL were as high as those of their normal counterparts; they were not related with genetic subgroups or differentiation stage. These results indicate that BLNK deficiency is a rare occurrence in childhood B-lineage ALL and is unlikely to be a common leukemogenic event as previously proposed.
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Affiliation(s)
- C Imai
- Department of Hematology-Oncology, St Jude Children's Research Hospital, North Lauderdale, Memphis, TN 38105-2794, USA
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97
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Su YW, Flemming A, Wossning T, Hobeika E, Reth M, Jumaa H. Identification of a pre-BCR lacking surrogate light chain. ACTA ACUST UNITED AC 2003; 198:1699-706. [PMID: 14638847 PMCID: PMC2194143 DOI: 10.1084/jem.20031428] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
SLP-65−/− pre-B cells show a high proliferation rate in vitro. We have shown previously that λ5 expression and consequently a conventional pre-B cell receptor (pre-BCR) are essential for this proliferation. Here, we show that pre-B cells express a novel receptor complex that contains a μ heavy chain (μHC) but lacks any surrogate (SL) or conventional light chain (LC). This SL-deficient pre-BCR (SL−pre-BCR) requires Ig-α for expression on the cell surface. Anti-μ treatment of pre-B cells expressing the SL−pre-BCR induces tyrosine phosphorylation of substrate proteins and a strong calcium (Ca2+) release. Further, the expression of the SL−pre-BCR is associated with a high differentiation rate toward κLC-positive cells. Given that B cell development is only partially blocked and allelic exclusion is unaffected in SL-deficient mice, we propose that the SL−pre-BCR is involved in these processes and therefore shares important functions with the conventional pre-BCR.
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Affiliation(s)
- Yu-Wen Su
- Institute for Biology III, Albert-Ludwigs University of Freiburg, Max Planck Institute for Immunobiology, Freiburg, Germany
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98
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Kersseboom R, Middendorp S, Dingjan GM, Dahlenborg K, Reth M, Jumaa H, Hendriks RW. Bruton's tyrosine kinase cooperates with the B cell linker protein SLP-65 as a tumor suppressor in Pre-B cells. J Exp Med 2003; 198:91-8. [PMID: 12835482 PMCID: PMC2196076 DOI: 10.1084/jem.20030615] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Expression of the pre-B cell receptor (pre-BCR) leads to activation of the adaptor molecule SLP-65 and the cytoplasmic kinase Btk. Mice deficient for one of these signaling proteins have an incomplete block in B cell development at the stage of large cycling pre-BCR+CD43+ pre-B cells. Our recent findings of defective SLP-65 expression in approximately 50% of childhood pre-B acute lymphoblastic leukemias and spontaneous pre-B cell lymphoma development in SLP-65-/- mice demonstrate that SLP-65 acts as a tumor suppressor. To investigate cooperation between Btk and SLP-65, we characterized the pre-B cell compartment in single and double mutant mice, and found that the two proteins have a synergistic role in the developmental progression of large cycling into small resting pre-B cells. We show that Btk/SLP-65 double mutant mice have a dramatically increased pre-B cell tumor incidence ( approximately 75% at 16 wk of age), as compared with SLP-65 single deficient mice (<10%). These findings demonstrate that Btk cooperates with SLP-65 as a tumor suppressor in pre-B cells. Furthermore, transgenic low-level expression of a constitutive active form of Btk, the E41K-Y223F mutant, prevented tumor formation in Btk/SLP-65 double mutant mice, indicating that constitutive active Btk can substitute for SLP-65 as a tumor suppressor.
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Affiliation(s)
- Rogier Kersseboom
- Department of Immunology, Erasmus MC Rotterdam, PO Box 1738, NL-3000 DR Rotterdam, Netherlands
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