The common viral insertion site Evi12 is located in the 5'-noncoding region of Gnn, a novel gene with enhanced expression in two subclasses of human acute myeloid leukemia

Retroviral insertion mutagenesis in mice as a comparative oncogenomics tool to identify disease genes in human leukemia

Retroviral insertion mutagenesis has recently received much attention because of its adverse effects in the application of retroviral vector-based gene therapy, resulting in leukemia in certain patients. At the same time, retroviral mutagenesis in mice is being considered a powerful forward genetic strategy to identify disease genes involved in cancer. The publication of the mouse genome sequence and the development of high-throughput genomic approaches have given a further boost to this rapidly evolving field. The increasing numbers of new potential oncogenes identified in retroviral screens have given a valuable basis for a better understanding of cancer related pathways in mice. Important challenges that now lie ahead of us are (i) to determine the relevance and causal relationship of these genes with various types of human cancer (ii) to develop strategies to identify tumor suppressor genes on a large scale, (iii) to place the disease genes into regulatory networks to better understand their role in the complex pathogenesis of cancer, and (iv) to determine their value for diagnosis refinement and therapeutic target intervention in human disease. In this review, we will give a brief update of the current state-of-the-art and thoughts concerning these issues. We will specifically focus on the value of employing retroviral insertion mutagenesis in mice and gene expression profiling in man in the context of acute myeloid leukemia.

Viral insertion in Evi12 causes expression of aberrant Grp94 mRNAs containing the viral gag myristylation motif

Ecotropic Virus Integration site 12 (Evi12) is a common virus insertion site (cVIS) in retrovirally induced murine models of leukemia and lymphoma, suggesting an important role for this locus in these hematopoietic disorders. Evi12 is located near the promoter of the ER chaperone protein and Hsp90 family member Grp94. Here we show that viral insertion in Evi12 results in the expression of aberrant Grp94 transcripts in Cas-Br-MuLV as well as in AKXD induced hematopoietic tumors, demonstrating that Grp94 is a common viral target gene. While most transcripts encode for truncated forms of Grp94, transcripts containing viral gag sequences were detected in the leukemia cell line NFS107. Interestingly, these fusion transcripts encode for myristylated viral-Grp94 fusion proteins that localize to the plasma membrane. Combined with recent evidence that myristylated forms of Hsp90 transform cells, our data suggest that myristylation of target genes may be an important mechanism in retrovirally mediated oncogenesis. Since retroviral insertion in Evi12 also affects the expression of a recently identified novel gene Grp94 neighboring nucleotidase (Gnn), located at the other side of Evi12, it appears that proviral insertion can lead to deregulation of two genes present in the same locus.

Association analysis of HSP90B1 with bipolar disorder

Pathophysiological role of endoplasmic reticulum (ER) stress response signaling has been suggested for bipolar disorder. The goal of this study was to test the genetic association between bipolar disorder and an ER chaperone gene, HSP90B1 (GRP94/gp96), which is located on a candidate locus, 12q23.3. We tested the genetic association between bipolar disorder and HSP90B1 by case-control studies in two independent Japanese sample sets and by a transmission disequilibrium test (TDT) in NIMH Genetics initiative bipolar trio samples (NIMH trios). We also performed gene expression analysis of HSP90B1 in lymphoblastoid cells. Among the 11 SNPs tested, rs17034977 showed significant association in both Japanese sample sets. The frequency of the SNP was lower in NIMH samples than in Japanese samples and there was no significant association in NIMH trios. Gene expression analysis of HSP90B1 in lymphoblastoid cells suggested a possible relationship between the associated SNP and mRNA levels. HSP90B1 may have a pathophysiological role in bipolar disorder in the Japanese population, though further study will be needed to understand the underlying functional mechanisms.

HeatMapper: powerful combined visualization of gene expression profile correlations, genotypes, phenotypes and sample characteristics

Background

Accurate interpretation of data obtained by unsupervised analysis of large scale expression profiling studies is currently frequently performed by visually combining sample-gene heatmaps and sample characteristics. This method is not optimal for comparing individual samples or groups of samples. Here, we describe an approach to visually integrate the results of unsupervised and supervised cluster analysis using a correlation plot and additional sample metadata.

Results

We have developed a tool called the HeatMapper that provides such visualizations in a dynamic and flexible manner and is available from .

Conclusion

The HeatMapper allows an accessible and comprehensive visualization of the results of gene expression profiling and cluster analysis.