Identification and characterization of the human homologue of SH3BP2, an SH3 binding domain protein within a common region of deletion at 4p16.3 involved in bladder cancer

Copy number variants suggest different molecular pathways for the pathogenesis of bladder exstrophy

Bladder exstrophy is a rare congenital malformation leaving the urinary bladder open in the midline of the abdomen at birth. There is a clear genetic background with chromosome aberrations, but so far, no consistent findings apart from 22q11-duplications detected in about 2%-3% of all patients. Some genes are implicated like the LZTR1, ISL1, CELSR3, and the WNT3 genes, but most are not explained molecularly. We have performed chromosomal microarray analysis on a cohort of 140 persons born with bladder exstrophy to look for submicroscopic chromosomal deletions and duplications. Pathogenic or possibly pathogenic microdeletions or duplications were found in 16 patients (11.4%) and further 9 with unknown significance. Two findings were in regions linked to known syndromes, two findings involved the same gene (MCC), and all other findings were unique. A closer analysis suggests a few gene networks that are involved in the pathogenesis of bladder exstrophy; the WNT-signaling pathway, the chromosome 22q11 region, the RIT2 and POU families, and involvement of the Golgi apparatus. Bladder exstrophy is a rare malformation and is reported to be associated with several chromosome aberrations. Our data suggest involvement of some specific molecular pathways.

SH3BP2-related fibro-osseous disorders of the maxilla and mandible: A systematic review

Cherubism is a disorder of bony overgrowth of the jaws that manifests in childhood. SH3BP2 gene variants have been associated with cherubism; this gene plays a major role in bone homeostasis. Due to its rare occurrence, there is as yet no comprehensive understanding of the natural history and clinical course of the disease. The aim of this review was to compile and analyze all cases of SH3BP2-related cherubism and cherubism-like disorders. Thirty publications were identified, including 92 individuals from 34 families, who were diagnosed with SH3BP2-related fibro-osseous lesions of the jaw. Only 15% of cases included in this review had no known family history of the disease. The distribution of cherubism was equal with respect to biological sex. Missing teeth were reported in 38% of cases. Lesions were restricted to the mandible in 36% of cases and involved both the maxilla and mandible in 54% of cases. The clinical phenotypes reported in the articles analyzed varied greatly in detail, making comparisons between studies and conclusive analysis difficult. Further work is necessary to describe the connection between SH3BP2 gene variants and cherubism in order to advance its diagnosis and treatment.

Identification of Tumor Microenvironment-Related Alternative Splicing Events to Predict the Prognosis of Endometrial Cancer

Background

Endometrial cancer (EC) is one of the most common female malignant tumors. The immunity is believed to be associated with EC patients’ survival, and growing studies have shown that aberrant alternative splicing (AS) might contribute to the progression of cancers.

Methods

We downloaded the clinical information and mRNA expression profiles of 542 tumor tissues and 23 normal tissues from The Cancer Genome Atlas (TCGA) database. ESTIMATE algorithm was carried out on each EC sample, and the OS-related different expressed AS (DEAS) events were identified by comparing the high and low stromal/immune scores groups. Next, we constructed a risk score model to predict the prognosis of EC patients. Finally, we used unsupervised cluster analysis to compare the relationship between prognosis and tumor immune microenvironment.

Results

The prognostic risk score model was constructed based on 16 OS-related DEAS events finally identified, and then we found that compared with high-risk group the OS in the low-risk group was notably better. Furthermore, according to the results of unsupervised cluster analysis, we found that the better the prognosis, the higher the patient’s ESTIMATE score and the higher the infiltration of immune cells.

Conclusions

We used bioinformatics to construct a gene signature to predict the prognosis of patients with EC. The gene signature was combined with tumor microenvironment (TME) and AS events, which allowed a deeper understanding of the immune status of EC patients, and also provided new insights for clinical patients with EC.

A 5-gene prognostic nomogram predicting survival probability of glioblastoma patients

BACKGROUND

Glioblastoma (GBM) remains the most biologically aggressive subtype of gliomas with an average survival of 10 to 12 months. Considering that the overall survival (OS) of each GBM patient is a key factor in the treatment of individuals, it is meaningful to predict the survival probability for GBM patients newly diagnosed in clinical practice.

MATERIAL AND METHODS

Using the TCGA dataset and two independent GEO datasets, we identified genes that are associated with the OS and differentially expressed between GBM tissues and the adjacent normal tissues. A robust likelihood-based survival modeling approach was applied to select the best genes for modeling. After the prognostic nomogram was generated, an independent dataset on different platform was used to evaluate its effectiveness.

RESULTS

We identified 168 differentially expressed genes associated with the OS. Five of these genes were selected to generate a gene prognostic nomogram. The external validation demonstrated that 5-gene prognostic nomogram has the capability of predicting the OS of GBM patients.

CONCLUSION

We developed a novel and convenient prognostic tool based on five genes that exhibited clinical value in predicting the survival probability for newly diagnosed GBM patients, and all of these five genes could represent potential target genes for the treatment of GBM. The development of this model will provide a good reference for cancer researchers.

Altered interphase fluorescence in situ hybridization profiles of chromosomes 4, 8q24, and 9q34 in pancreatic ductal adenocarcinoma are associated with a poorer patient outcome

Most patients with pancreatic ductal adenocarcinoma (PDAC) die within 6 months of diagnosis. However, 20% to 25% patients undergoing total tumor resection remain alive and disease-free 5 years after diagnostic surgery. Few studies on tumor markers have predicted patient prognosis and/or survival. We evaluated the effect of tumor cytogenetic copy number changes detected by interphase fluorescence in situ hybridization on overall survival (OS) of 55 PDAC patients. The prognostic value of copy number changes showing an effect on OS was validated in an external cohort of 44 surgically resected PDAC patients by comparative genomic hybridization arrays, and the genes coded in altered chromosomes with prognostic value were identified by high-density single-nucleotide polymorphism arrays in 20 cases. Copy number changes of chromosomes 4 and 9q34 with gains of 8q24 were independently associated with shorter OS. On the basis of these three chromosomal alterations, a score is proposed that identifies patients with significantly different (P < 0.001) 5-year OS rates: 60% ± 20%, 16% ± 8%, and 0% ± 0%, respectively. Our results show an association between tumor cytogenetics and OS of PDAC patients and provide the basis for further prognostic stratification of patients undergoing complete tumor resection. Further studies to identify specific genes coded in these chromosomes and their functional consequences are necessary to understand the clinical effect of these changes.

An integrated genomic, transcriptional and protein investigation of FGFRL1 as a putative 4p16.3 deletion target in bladder cancer

Loss of heterozygosity (LOH) of chromosome arm 4p is a common event in bladder and other malignancies. At least three distinct regions of deletion have been identified, but the deletion targets have so far remained elusive. In this study, we have identified a novel region of deletion mapping to 4p16.3 spanning 0-2.1 Mb, in 15% of bladder tumors and 24% of bladder cancer cell lines. FGFRL1, which maps within this region, was investigated as putative deletion target. The retained FGFRL1 allele was not mutated in cell lines and tumors with LOH, although in patients heterozygous for the rs4647930 functional polymorphism, the common allele was preferentially lost in tumor tissue. Epigenetic silencing of the retained allele was also excluded as levels of FGFRL1 mRNA and protein were similar in cell lines and tumors with and without 4p16.3 loss. However, while FGFRL1 protein was moderately expressed in all layers of the normal bladder epithelium, the majority of tumors showed areas of downregulation. Overall, average FGFRL1 protein expression was significantly lower in bladder tumors compared to normal tissue, but downregulation was independent from 4p16.3 LOH status, FGFR3 mutation, and tumor grade and stage. In conclusion, although we found no evidence supporting a "two-hit" inactivation of FGFRL1 in bladder carcinogenesis, the effect of heterozygous deletion coupled with functional polymorphisms, and the role of post-transcriptional downregulation deserves further investigation.

The role of SH3BP2 in the pathophysiology of cherubism

Cherubism is a rare bone dysplasia that is characterized by symmetrical bone resorption limited to the jaws. Bone lesions are filled with soft fibrous giant cell-rich tissue that can expand and cause severe facial deformity. The disorder typically begins in children at ages of 2-5 years and the bone resorption and facial swelling continues until puberty; in most cases the lesions regress spontaneously thereafter. Most patients with cherubism have germline mutations in the gene encoding SH3BP2, an adapter protein involved in adaptive and innate immune response signaling. A mouse model carrying a Pro416Arg mutation in SH3BP2 develops osteopenia and expansile lytic lesions in bone and some soft tissue organs. In this review we discuss the genetics of cherubism, the biological functions of SH3BP2 and the analysis of the mouse model. The data suggest that the underlying cause for cherubism is a systemic autoinflammatory response to physiologic challenges despite the localized appearance of bone resorption and fibrous expansion to the jaws in humans.

SH3BP2-encoding exons involved in cherubism are not associated with central giant cell granuloma

Central giant cell granuloma (CGCG) is a benign lesion with unpredictable biological behaviour ranging from a slow-growing asymptomatic swelling to an aggressive lesion associated with pain, bone and root resorption and also tooth displacement. The aetiology of the disease is unclear with controversies in the literature on whether it is mainly of reactional, inflammatory, infectious, neoplasic or genetic origin. To test the hypothesis that mutations in the SH3BP2 gene, as the principal cause of cherubism, are also responsible for, or at least associated with, giant cell lesions, 30 patients with CGCG were recruited for this study and subjected to analysis of germ line and/or somatic alterations. In the blood samples of nine patients, one codon alteration in exon 4 was found, but this alteration did not lead to changes at the amino acid level. In conclusion, if a primary genetic defect is the cause for CGCG it is either located in SH3BP2 gene exons not yet related to cherubism or in a different gene.

Increased expression of NFATc1 in giant cell lesions of the jaws, cherubism and brown tumor of hyperparathyroidism

A variety of diseases of the jaws may present multinucleated giant cells. These diseases include central giant cell lesions (CGCL), peripheral giant cell lesions (PGCL), brown tumor of hyperparathyroidism (BTH), and cherubism. The multinucleated giant cells in these lesions are osteoclast-like. Since NFATc1 plays a significant role in osteoclast differentiation, the present study aimed to compare the expression of NFATc1 in CGCL, PGCL, BTH and cherubism. A total of 14 formalin-fixed and paraffin-embedded tissue samples of CGCL (n=4), PGCL (n=5), BTH (n=3) and cherubism (n=2) were included in the study. An immunohistochemical analysis was performed to investigate the NFATc1 protein. The majority of giant cells in all of the cases were positive for nuclear NFATc1 and the immunostaining pattern was similar in all of the groups. Although our study supports the hypothesis that giant cell accumulation in PGCL, CGCL, BTH and cherubism is mediated by NFATc1, functional studies are required to investigate this hypothesis.

A novel mutation of the SH3BP2 gene in an aggressive case of cherubism

Cherubism is an autosomal dominant inherited syndrome characterized by excessive bone degradation of upper and lower jaw and its replacement with large amounts of fibrous tissue, which causes a characteristic facial swelling. A correlation with a mutation in the gene SH3BP2 has been previously demonstrated, but a model for its pathogenesis is not yet available. Here we describe a novel mutation in an aggressive case of cherubism located in the pleckstrin homology domain (PH) of the SH3BP2.

Characterization of a novel Xenopus SH3 domain binding protein 5 like (xSH3BP5L) gene

SH3 domain binding protein 5 like (xSH3BP5L) gene encodes a protein that is a new found member of SH3 domain binding protein family which has been implicated at multiple levels of biological functions. Here, we have characterized Xenopus SH3 domain binding protein 5 like (xSH3BP5L) gene in the development of Xenopus laevis. Transcripts of xSH3BP5L were detected at all stages of development and in numerous adult tissues. Whole-mount in situ hybridization demonstrated that xSH3BP5L is expressed at the animal pole from stage-2 onward. Interestingly, translational inhibition of xSH3BP5L using antisense morpholino oligonucleotides (MOs) and overexpression of xSH3BP5L in Xenopus embryos resulted in failed or delayed blastopore closure. Taken together, these data suggested that xSH3BP5L is required for normal embryogenesis of blastopore closure in X. laevis.

[The adaptor protein 3BP2 in leukocyte signaling]

Adaptor proteins that do not contain intrinsic enzymatic activity play a critical role in cell biology by regulating the assembly of large multimolecular signaling complexes involved in extracellular signal transduction. The increasing number of diseases associated with aberrant function or expression of adaptor proteins further illustrate their key role in cellular regulation. The adaptor 3BP2 (or SH3BP2) was originally identified more than 10 years ago as an c-Abl binding protein, and next as a partner of Syk family kinases in 1998. 3BP2 displays the typical modular organization of an adapter protein with an amino-terminal PH domain, a central proline rich region and a carboxyl-terminal SH2 domain. Although its physiological function remains unknown, studies have implicated a role for 3BP2 in immunoreceptor signaling through its interaction with a number of signaling molecules including Src and Syk families of protein tyrosine kinases, the membrane adaptor LAT, Vav exchange factors, PLC-gamma, and 14-3-3 proteins. Recently, the 3bp2/sh3bp2 locus was shown to be mutated in a rare human disease involved in cranial-facial development called cherubism, suggesting a role for 3BP2 in regulating osteoclast and hematopoietic cell function.

SH3BP2 is rarely mutated in exon 9 in giant cell lesions outside cherubism

Giant cell tumor of bone and giant cell reparative granuloma are benign lesions with prominent giant (multinucleated) cells, and an understanding of the molecular biology and genetics of these lesions will likely aid in more effective treatment. Cherubism is a benign lesion of the maxilla and mandible histologically similar to giant cell tumor of bone and giant cell reparative granuloma. Germline mutations in exon 9 of the gene encoding Src homology 3 binding protein 2 (SH3BP2) occur in most patients with cherubism. We therefore hypothesized SH3BP2 and its putative downstream effector nuclear factor of activated T cells c1 isoform (NFATc1) are highly expressed in sporadic nonsyndromic giant cell lesions and associated with somatic SH3BP2 mutations. We analyzed giant cell lesions for SH3BP2 and NFATc1 expression by RNA blot and/or immunohistochemistry and for exon 9 SH3BP2 mutations. We found the SH3BP2 transcripts and protein were abundantly expressed in giant cell tumors of bone, as well as NFATc1 protein. Sequencing of exon 9 of SH3BP2 was normal in all sporadic nonsyndromic giant cell lesions. Although many multinucleated giant cell lesions of bone share histologic features, the primary genetic defect in cherubism and these other giant cell lesions appears different.

Abl-SH3 binding protein 2, 3BP2, interacts with CIN85 and HIP-55

The adapter 3BP2 is involved in leukocyte signaling downstream Src/Syk-kinases coupled immunoreceptors. Here, we show that 3BP2 directly interacts with the endocytic scaffold protein CIN85 and the actin-binding protein HIP-55. 3BP2 co-localized with CIN85 and HIP-55 in T cell rafts and at the T cell/APC synapse, an active zone of receptors and proteins recycling. A binding region of CIN85 SH3 domains on 3BP2 was mapped to a PVPTPR motif in the first proline-rich region of 3BP2, whereas the C-terminal SH3 domain of HIP-55 bound a more distal proline-rich domain of 3BP2. Together, our data suggest an unexpected role of 3BP2 in endocytic and cytoskeletal regulation through its interaction with CIN85 and HIP-55.

Cherubism – new hypotheses on pathogenesis and therapeutic consequences

AIMS

The hereditary occurrence of cherubism indicates a probable genetic aetiology: a correlation with a mutation in the gene SH3BP2 has been demonstrated. A convincing concept of formal pathogenesis is not yet available. The study was aimed at advancing the understanding of the pathogenesis of cherubism by presenting a case study including genetic findings and an evaluation of the literature.

RESULTS AND CONCLUSION

Because of its association with the development of the second and third molars, cherubism could be defined as a genetically determined alteration of tooth development. In this context, disturbed PTHrP - PTHrP receptor interaction induced by the mutation in SH3BP2 is discussed. The temporal and spatial determination of the clinical symptoms is explained by an interaction of SH3BP2-dependent signal transduction pathways with jaw morphogenesis (e.g. Hox-gene Msx-1). Because of the disease-induced lack of determination of the cap phase of the second and third molar, a spatial compartmentation, which is necessary for normal dental development, does not take place. This leads to dysregulation of mesenchymal bone building tissue areas, and to the development of giant cell granulomas with high osteoclastic activity. Because of the genetic determination of cherubism and the associated dedifferentiation of the diseased tissue, a surgical removal should be exclusively restricted to specific indications. Therefore an attitude of wait and see is preferred.

Point mutations of 3BP2 identified in human-inherited disease cherubism result in the loss of function

Adaptor protein 3BP2 positively regulates the high affinity IgE receptor (FcepsilonRI)-mediated activation of degranulation in mast cells. Genetic study identified the point mutations of 3BP2 gene in human-inherited disease cherubism. The multiple cysts in cherubism lesion of jaw bones are filled with the activated osteoclasts and stromal cells, including mast cells. By over-expression study using rat basophilic leukaemia RBL-2H3 mast cells, we have analysed the effect of the point mutations on the function of 3BP2 protein, which plays a positive regulatory role on FcepsilonRI-mediated mast cell activation. Over-expression of 3BP2 mutants suppressed the antigen-induced degranulation and cytokine gene transcription. Antigen-induced phosphorylation of Vav1, activation of Rac1, extracellular signal regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38 mitogen activated protein kinase (MAPK), inhibitor of nuclear factor kappaB kinase (IKK) and nuclear factor of activated T cells (NFAT) were all impaired in the cells over-expressing the cherubism mutants of 3BP2. Furthermore, cherubism mutations of 3BP2 may abrogate the binding ability to interact with chaperone protein 14-3-3. These results demonstrate that over-expression of the mutant form of 3BP2 inhibits the antigen-induced mast cell activation. It suggests that point mutations of 3BP2 gene cause the dysfunction of 3BP2 in vivo.

The adaptor protein 3BP2 associates with VAV guanine nucleotide exchange factors to regulate NFAT activation by the B-cell antigen receptor

Engagement of the B-cell antigen receptor (BCR) activates kinases of the Src and Syk families and signaling complexes assembled by adaptor proteins, which dictate B-cell fate and function. The adaptor 3BP2/SH3BP2, an Abl Src homology domain 3 (SH3)-binding and Syk-kinases interacting protein, exhibits positive regulatory roles in T, natural killer (NK), and basophilic cells. However, its involvement in BCR signaling is completely unknown. Here we show that 3BP2 is tyrosine phosphorylated following BCR aggregation on B lymphoma cells, and that 3BP2 is a substrate for Syk and Fyn, but not Btk. To further explore the function of 3BP2 in B cells, we screened a yeast 2-hybrid B-lymphocyte library and found 3BP2 as a binding partner of Vav proteins. The interaction between 3BP2 and Vav proteins involved both constitutive and inducible mechanisms. 3BP2 also interacted with other components of the BCR signaling pathway, including Syk and phospholipase C gamma (PLC-gamma). Furthermore, overexpression and RNAi blocking experiments showed that 3BP2 regulated BCR-mediated activation of nuclear factor of activated T cells (NFATs). Finally, evidence was provided that 3BP2 functionally cooperates with Vav proteins and Rho GTPases to activate NFATs. Our results show that 3BP2 may regulate BCR-mediated gene activation through Vav proteins.

90-kDa ribosomal S6 kinase is a direct target for the nuclear fibroblast growth factor receptor 1 (FGFR1): role in FGFR1 signaling

Fibroblast growth factor receptor 1 (FGFR1) is a transmembrane protein capable of transducing stimulation by secreted FGFs. In addition, newly synthesized FGFR1 enters the nucleus in response to cellular stimulation and during development. Nuclear FGFR1 can transactivate CRE (cAMP responsive element), activate CRE-binding protein (CREB)-binding protein (CBP) and gene activities causing cellular growth and differentiation. Here, a yeast two-hybrid assay was performed to identify FGFR1-binding proteins and the mechanism of nuclear FGFR1 action. Ten FGFR1-binding proteins were identified. Among the proteins detected with the intracellular FGFR1 domain was a 90-kDa ribosomal S6 kinase (RSK1), a regulator of CREB, CBP, and histone phosphorylation. FGFR1 bound to the N-terminal region of RSK1. The FGFR1-RSK1 interaction was confirmed by co-immunoprecipitation and colocalization in the nucleus and cytoplasm of mammalian cells. Predominantly nuclear FGFR1-RSK1 interaction was observed in the rat brain during neurogenesis and in cAMP-stimulated cultured neural cells. In TE671 cells, transfected FGFR1 colocalized and coimmunoprecipitated, almost exclusively, with nuclear RSK1. Nuclear RSK1 kinase activity and RSK1 activation of CREB were enhanced by transfected FGFR1. In contrast, kinase-deleted FGFR1 (TK-), which did not bind to RSK1 failed to stimulate nuclear RSK1 activity or RSK1 activation of CREB. Kinase inactive FGFR1 (K514A) bound effectively to nuclear RSK1, but it failed to stimulate RSK1. Thus, active FGFR1 kinase regulates the functions of nuclear RSK1. The interaction of nuclear FGFR1 with pluripotent RSK1 offers a new mechanism through which FGFR1 may control fundamental cellular processes.

Novel mutation in the gene encoding c-Abl-binding protein SH3BP2 causes cherubism

Cherubism is a rare autosomal dominant inherited condition caused by mutations in the c-Abl-binding protein SH3BP2. It is characterized by multiple cystic giant cell lesions of the jaw appearing in early childhood with stabilization and remission after puberty. In the present study, we used direct sequence analysis of the SH3BP2 gene of several individuals from a family with cherubism to search for additional SH3BP2 mutations resulting in cherubism. In affected relatives, we found a previously unreported G to A transition in exon 9 leading to a Gly to Arg substitution at amino acid position 420. G420R has been reported previously with a G to C transversion. To date there have been no disease causing mutations outside exon 9. Therefore, the amino acid sequence from positions 415 to 420 may represent a specific protein domain which, when disrupted, leads to the cherubism phenotype.

The chaperone protein 14-3-3 interacts with 3BP2/SH3BP2 and regulates its adapter function

Lymphocyte stimulation by immunoreceptors is achieved through the activation of multiple signaling pathways leading to cytokine gene transcription. Adapter proteins are critical signaling components that can integrate multiple pathways by allowing the assembly of multimolecular signaling complexes. We previously showed that the cytoplasmic adapter 3BP2 (also known as SH3BP2) promotes NFAT/AP-1 transcriptional activities in T cells through the activation of Ras- and calcineurin-dependent pathways. However, the molecular mechanisms by which 3BP2/SH3BP2 regulates cell signaling and activation remain poorly documented. In this study, using a combination of yeast two-hybrid analysis and biochemical approaches, we present evidence for a physical interaction between 3BP2 and the chaperone protein 14-3-3. This interaction was direct and constitutively detected in yeast and in mammalian cells. Phorbol ester, pervanadate, and forskolin/isobutylmethylxanthine stimulations enhanced this interaction, as well as co-expression of constitutive active mutants of serine/threonine kinases, including protein kinase C. We found that dephosphorylation of 3BP2 by alkaline phosphatase disrupted its interaction with 14-3-3 and that 3BP2 was a substrate of purified protein kinase C in vitro, suggesting that the phosphorylation of 3BP2 by upstream kinases was required for 14-3-3 binding. Using deletion mutants of 3BP2, two 14-3-3 binding domains were mapped to two proline-rich (residues 201-240 and 270-310) domains of 3BP2. These domains were shown to contain two 14-3-3 consensus binding motifs. We identified residues Ser(225) and Ser(277) of 3BP2 as being essential for interaction with 14-3-3 family proteins, optimal 3BP2 serine phosphorylation, and then for 3BP2-dependent function. Indeed, a 3BP2 mutant protein incapable of binding 14-3-3 showed increased capacity to stimulate NFAT transcriptional activities, suggesting that 14-3-3 binding to 3BP2 negatively regulates 3BP2 adapter function in lymphocytes.

A high-resolution allelotype of B-cell chronic lymphocytic leukemia (B-CLL)

The most frequent chromosomal aberrations in B-cell chronic lymphocytic leukemia (B-CLL) are deletions on 13q, 11q, and 17p, and trisomy 12, all of which are of prognostic significance. Conventional cytogenetic analysis and fluorescence in situ hybridization (FISH) are used for their detection, but cytogenetic analysis is hampered by the low mitotic index of B-CLL cells, and FISH depends on accurate information about candidate regions. We used a set of 400 highly informative microsatellite markers covering all chromosomal arms (allelotyping) and automated polymerase chain reaction (PCR) protocols to screen 46 patients with typical B-CLL for chromosomal aberrations. For validation, we compared data with our conventional karyotype results and fine mapping with conventional single-site PCR. All clonal cytogenetic abnormalities potentially detectable by our microsatellite PCR (eg, del13q14 and trisomy 12) were picked up. Allelotyping revealed additional complex aberrations in patients with both normal and abnormal B-CLL karyotypes. Aberrations detectable in the samples with our microsatellite panel were found on almost all chromosomal arms. We detected new aberrant loci in typical B-CLL, such as allelic losses on 1q, 9q, and 22q in up to 25% of our patients, and allelic imbalances mirroring chromosomal duplications, amplifications, or aneuploidies on 2q, 10p, and 22q in up to 27% of our patients. We conclude that allelotyping with our battery of informative microsatellites is suitable for molecular screening of B-CLL. The technique is well suited for analyses in clinical trials, it provides a comprehensive view of genetic alterations, and it may identify new loci with candidate genes relevant in the molecular biology of B-CLL.

Regulation of NK cell-mediated cytotoxicity by the adaptor protein 3BP2

Stimulation of lymphocytes through multichain immune recognition receptors activates multiple signaling pathways. Adaptor proteins play an important role in integrating these pathways by their ability to simultaneously bind multiple signaling components. Recently, the 3BP2 adaptor protein has been shown to positively regulate the transcriptional activity of T cells. However, the mechanisms by which signaling components are involved in this regulation remain unclear, as does a potential role for 3BP2 in the regulation of other cellular functions. Here we describe a positive regulatory role for 3BP2 in NK cell-mediated cytotoxicity. We also identify p95(vav) and phospholipase C-gamma isoforms as binding partners of 3BP2. Our results show that tyrosine-183 of 3BP2 is specifically involved in this interaction and that this residue critically influences 3BP2-dependent function. Therefore, 3BP2 regulates NK cell-mediated cytotoxicity by mobilizing key downstream signaling effectors.

Mutations in the gene encoding c-Abl-binding protein SH3BP2 cause cherubism

Cherubism (MIM 118400) is an autosomal dominant inherited syndrome characterized by excessive bone degradation of the upper and lower jaws followed by development of fibrous tissue masses, which causes a characteristic facial swelling. Here we describe seven mutations in the SH3-binding protein SH3BP2 (MIM 602104) on chromosome 4p16.3 that cause cherubism.