During this reporting period, we examined the roles of GATA-1 and GATA-2 in activating transcription of the secretory ribonuclease, the eosinophil-derived neurotoxin (EDN/RNase 2). Augmented expression of both GATA-1 and GATA-2 was detected in eosinophils and deletion or mutation of one or both of the two consensus GATA-binding sites in the extended 5'promoter of the EDN/RNase2 gene resulted in profound reduction in reporter gene activity. Antibody-augmented electrophoretic mobility shift and chromatin immunoprecipitation analyses indicate that GATA-1 and GATA-2 proteins bind to both functional GATA consensus sequences in the EDN promoter. Interestingly, RNA silencing of GATA-1 alone had no impact on EDN/RNase2 expression;silencing of GATA-2 resulted in diminished expression of EDN, and also diminished expression of GATA-1 in both butyric acid-induced HL-60 clone 15 cells and in differentiating human eosinophils derived from CD34(+) hematopoietic progenitors. Likewise, overexpression of GATA-2 in resulted in augmented transcription of both EDN/RNase2 and GATA-1. Taken together, our data suggest that GATA-2 functions directly via interactions with the EDN promoter and also indirectly, via its ability to regulate the expression of GATA-1 in differentiating eosinophils (Qiu et al. J Biol Chem. 2009). Another publication focuses on the diversity of mammalian RNase A ribonucleases, and completes some outstanding work from Dr. Wei Zhao's visiting professorship with our group. This manuscript, which identifies a novel cluster of rodent RNase 1 genes, serves also to complete and to correct several erroneous entries in GenBank database (Siegel et al. Mamm Genome, 2009, in press) I continue to serve on the Editorial Board of Journal of Biological Chemistry (since 2008), a largely due to my expertise in Ribonuclease Biology and Biochemistry.
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