Protein/DNA arrays identify nitric oxide-regulated cis-element and trans-factor activities some of which govern neuroblastoma cell viability.

Toxic nitric oxide (NO) levels can regulate gene expression. Using a novel protein/DNA array, we show that toxic NO levels regulate the binding of trans-factors to various cis-elements in neuroblastoma cells, including CRE and those recognized by the transcription factors AP1, AP2, Brn-3a, EGR, E2F1 and SP1. Functionality of some of the cis-elements was confirmed by electro mobility shift and reporter assays.

Artificial zinc(II) complexes regulate cell cycle and apoptosis-related genes in tumor cell lines.

Various proteins involved in transcriptional regulation possess highly selective DNA-binding domains, known as zinc fingers. However, little is known about small-molecule zinc(II) complexes in the regulation of gene expression and programmed cell death. A new family of zinc(II) complexes is reported, which might be useful against human cancer cells.

Role of the cyclic AMP response element in the bcl-2 promoter in the regulation of endogenous Bcl-2 expression and apoptosis in murine B cells.

We have previously shown for B-cell lines that the cyclic AMP response element (CRE) is a major positive regulatory site in the bcl-2 promoter. However, the role of the CRE in the regulation of endogenous bcl-2 expression in vivo has not been characterized. We used gene targeting to generate knock-in mice in which a mutated CRE was introduced into the bcl-2 promoter region (mutCRE-bcl2 mice).

Transcription factor gata4 regulates cardiac BCL2 gene expression in vitro and in vivo.

The transcription factor GATA-4 protects cardiomyocytes against doxorubicin-induced cardiotoxicity. Here, we report the identification of Bcl2 as a direct target gene of GATA4 that may mediate the prosurvival function of GATA4 in cardiomyocytes. Bcl2 transcript and protein levels were reduced by doxorubicin in neonatal rat ventricular cardiomyocytes (NRVC) and in mouse heart as determined by RT-PCR and Western blot analysis.

CCAAT/enhancer binding protein alpha (C/EBPalpha) and C/EBPalpha myeloid oncoproteins induce bcl-2 via interaction of their basic regions with nuclear factor-kappaB p50.

The CEBPA gene is mutated in 10% of acute myeloid leukemia (AML) cases. We find that CEBPA and Bcl-2 RNA levels correlate highly in low-risk human AMLs, suggesting that inhibition of apoptosis via induction of bcl-2 by CCAAT/enhancer binding protein alpha (C/EBPalpha) or its mutant variants contributes to transformation. C/EBPalphap30, lacking a NH2-terminal transactivation domain, or C/EBPalphaLZ, carrying in-frame mutations in the leucine zipper that prevent DNA binding, induced bcl-2 in hematopoietic cell lines, and C/EBPalpha induced bcl-2 in normal murine myeloid progenitors and in the splenocytes of H2K-C/EBPalpha-Emu transgenic mice.

Histone deacetylase inhibitors down-regulate bcl-2 expression and induce apoptosis in t(14;18) lymphomas.

Histone deacetylase (HDAC) inhibitors are promising antitumor agents, but they have not been extensively explored in B-cell lymphomas. Many of these lymphomas have the t(14;18) translocation, which results in increased bcl-2 expression and resistance to apoptosis. In this study, we examined the effects of two structurally different HDAC inhibitors, trichostatin A (TSA) and sodium butyrate (NaB), on the cell cycle, apoptosis, and bcl-2 expression in t(14;18) lymphoma cells.

Regulatory elements in the immunoglobulin heavy chain gene 3'-enhancers induce c-myc deregulation and lymphomagenesis in murine B cells.

Burkitt's lymphoma is invariably associated with chromosomal translocations that juxtapose the c-myc proto-oncogene with regulatory elements of the immunoglobulin heavy (IgH) or light chain loci resulting in the deregulation of c-myc expression. However, the enhancer elements mediating c-myc deregulation in vivo remain largely unidentified. To investigate the role of the IgH 3'-enhancers in c-myc deregulation, we used gene targeting to generate knock-in mice in which four DNase I hypersensitive regions from the murine IgH 3'-region were integrated into the 5'-region of the c-myc locus.

A genome-wide view of the in vitro response to l-asparaginase in acute lymphoblastic leukemia.

To investigate the effect of l-asparaginase on acute lymphoblastic leukemia (ALL), we used cDNA microarrays to obtain a genome-wide view of gene expression both at baseline and after in vitro exposure to l-asparaginase in cell lines and pediatric ALL samples. In 16 cell lines, a baseline gene expression pattern distinguished l-asparaginase sensitivity from resistance. However, for 28 pediatric ALL samples, no consistent baseline expression pattern was associated with sensitivity to l-asparaginase.

Neurotrophin-3 and a CREB-mediated signaling pathway regulate Bcl-2 expression in oligodendrocyte progenitor cells.

Our previous results suggested that the transcription factor CREB mediates the actions of neuroligands and growth factor signals that coupled to different signaling pathways may play different roles along oligodendrocyte (OLG) development. We showed before that CREB phosphorylation in OLG progenitors is up-regulated by neurotrophin-3 (NT-3); and moreover CREB is required for NT-3 to stimulate the proliferation of these cells. We now show that treatment of OLG progenitors with NT-3 is also accompanied by an increase in the levels of the anti-apoptotic protein Bcl-2.

Critical elements of the immunoglobulin heavy chain gene enhancers for deregulated expression of bcl-2.

Translocation of the bcl-2 gene to the immunoglobulin heavy chain gene is the most common alteration in follicular lymphoma. The result is the deregulated expression of bcl-2 and increased resistance to cell death. Regulation of the immunoglobulin heavy chain gene is controlled in part by four DNase I-hypersensitive regions located 3' of the gene.

Gene expression patterns associated with recurrent chromosomal translocations in acute lymphoblastic leukemia.

We obtained a global view of gene expression in both cell lines and pediatric acute lymphoblastic leukemia (ALL) samples that harbor one of several selected chromosomal abnormalities. When the cell lines were studied alone, we found that these chromosomal abnormalities were associated with the predominant variation in transcriptional programs across the set of cell lines studied. When cell lines and clinical samples were studied together, we found that each chromosomal abnormality (TEL/AML1, BCR/ABL, or MLL abnormalities) was associated with a characteristic gene expression signature that was shared by both cell lines and clinical samples.

Regulation of Bcl-2 expression by C/EBP in t(14;18) lymphoma cells.

In follicular lymphomas with the t(14;18) translocation, there is increased expression of the bcl-2 gene, which is dependent upon regulatory elements within the bcl-2 5' flanking region and the immunoglobulin heavy-chain gene enhancers. We found that t(14;18) lymphomas expressed C/EBPalpha, which is not normally expressed in B lymphocytes. Expression of C/EBPalpha increased bcl-2 expression, and two regions of the bcl-2 P2 promoter that mediated this effect were identified.

Cytokine-mediated down-regulation of the transcription factor cAMP-response element-binding protein in pancreatic beta-cells.

Cytokines are known to induce apoptosis of pancreatic beta-cells. Impaired expression of the anti-apoptotic gene bcl-2 is one of the mechanisms involved. In this study, we identified a defect involving transcription factor cAMP-response element-binding protein (CREB) in the expression of bcl-2.

Oxidative stress-mediated down-regulation of bcl-2 promoter in hippocampal neurons.

Generation of oxidative stress/reactive oxygen species (ROS) is one of the causes of neuronal apoptosis. We have examined the effects of ROS at the transcriptional level in an immortalized hippocampal neuronal cell line (H19-7) and in rat primary hippocampal neurons. Treatment of H19-7 cells with hydrogen peroxide (150 micro m) resulted in a 40% decrease in Bcl-2 protein and a parallel decrease in bcl-2 mRNA levels.

Impaired proliferation and survival of activated B cells in transgenic mice that express a dominant-negative cAMP-response element-binding protein transcription factor in B cells.

The cAMP-response element-binding protein (CREB) is activated by phosphorylation on serine 133 and mediates the proliferative response to a number of different signals. A mutant CREB with a serine to alanine substitution at position 133 (CREBM1) functions as a dominant-negative inhibitor. Transgenic mice that express the dominant-negative CREB protein in B lymphocytes were developed as a means to study the effects of the inhibition of CREB function on B-cell proliferation and survival.

Allele-specific analysis of transcription factors binding to promoter regions.

In vivo footprinting techniques are useful for the identification of regulatory elements mediating transcriptional control of a gene. However, regulation of a gene can differ between the two alleles, and further steps must be taken to distinguish between the regulatory elements occupied on one allele and those used on the second allele. Many hematologic malignancies result from chromosomal translocations, which, in some cases, relocate a gene to a transcriptionally active region leading to the deregulated expression of that gene.

NF-kappaB activates Bcl-2 expression in t(14;18) lymphoma cells.

The t(14;18) translocation, which is characteristic of follicular lymphoma, results in the overexpression of the bcl-2 gene dependent upon regulatory elements within the bcl-2 5' flanking region and the immunoglobulin heavy chain gene enhancers. Conflicting evidence exists on the effects of NF-kappaB expression on Bcl-2 levels in different cell types. Lymphoma cells with the t(14;18) translocation show high levels of nuclear NF-kappaB proteins.

A Myc-associated zinc finger protein-related factor binding site is required for the deregulation of c-myc expression by the immunoglobulin heavy chain gene enhancers in Burkitt's lymphoma.

The deregulation of expression of the c-myc gene in Burkitt's lymphoma results from the translocation that links one c-myc allele to one of the immunoglobulin genes. This physical linkage promotes interactions between c-myc and immunoglobulin gene regulatory elements that affect c-myc transcription initiation and elongation. We have located a region in the c-myc promoter that is required for the complete activation by the immunoglobulin heavy chain gene enhancer.