Though genome-wide association studies (GWAS) have identified the existence of numerous population-based cancer susceptibility loci, mechanistic insights remain limited, particularly for intergenic polymorphisms. Here we show that polymorphism at a remote intergenic region on chromosome 11q13.3, recently identified as a susceptibility locus for renal cell carcinoma1, modulates the binding and function of hypoxia inducible factor (HIF) at a previously unrecognized, transcriptional enhancer of cyclin D1 specific for renal cancers characterized by pVHL inactivation. The protective haplotype impairs binding of HIF-2 resulting in an allelic imbalance in cyclin D1 expression, thus affecting a link between hypoxia pathways and cell cycle control.

The adaptation of erythropoietin production to oxygen supply is determined by the abundance of hypoxia-inducible factor (HIF), a regulation that is induced by a prolyl hydroxylase. To identify cells that express HIF subunits (HIF-1alpha and HIF-2alpha) and erythropoietin, we treated Sprague-Dawley rats with the prolyl hydroxylase inhibitor FG-4497 for 6 h to induce HIF-dependent erythropoietin transcription. The kidneys were analyzed for colocalization of erythropoietin mRNA with HIF-1alpha and/or HIF-2alpha protein along with cell-specific identification markers. FG-4497 treatment strongly induced erythropoietin mRNA exclusively in cortical interstitial fibroblasts. Accumulation of HIF-2alpha was observed in these fibroblasts and in endothelial and glomerular cells, whereas HIF-1alpha was induced only in tubular epithelia. A large proportion (over 90% in the juxtamedullary cortex) of erythropoietin-expressing cells coexpressed HIF-2alpha. No colocalization of erythropoietin and HIF-1alpha was found. Hence, we conclude that in the adult kidney, HIF-2alpha and erythropoietin mRNA colocalize only in cortical interstitial fibroblasts, which makes them the key cell type for renal erythropoietin synthesis as regulated by HIF-2alpha.

General activation of hypoxia-inducible factor (HIF) pathways is classically associated with adverse prognosis in cancer and has been proposed to contribute to oncogenic drive. In clear cell renal carcinoma (CCRC) HIF pathways are upregulated by inactivation of the von-Hippel-Lindau tumor suppressor. However HIF-1α and HIF-2α have contrasting effects on experimental tumor progression. To better understand this paradox we examined pan-genomic patterns of HIF DNA binding and associated gene expression in response to manipulation of HIF-1α and HIF-2α and related the findings to CCRC prognosis. Our findings reveal distinct pan-genomic organization of canonical and non-canonical HIF isoform-specific DNA binding at thousands of sites. Overall associations were observed between HIF-1α-specific binding, and genes associated with favorable prognosis and between HIF-2α-specific binding and adverse prognosis. However within each isoform-specific set, individual gene associations were heterogeneous in sign and magnitude, suggesting that activation of each HIF-α isoform contributes a highly complex mix of pro- and anti-tumorigenic effects.

Tumor necrosis factor aPromoter regulation a b s t r a c tWe identified the Wilms' tumor protein, Wt1, as a novel transcriptional activator of the immunosuppressant cytokine interleukin-10 (IL-10). Silencing of Wt1 by RNA interference reduced IL-10 mRNA levels by approximately 90%. IL-10 transcripts were increased more than 15-fold upon forced expression of Wt1. Electrophoretic mobility shift assay and chromatin immunoprecipitation revealed a cis-element that was responsible for activation of the IL-10 promoter by Wt1 in murine macrophages. Mutation of the Wt1 binding motif abrogated stimulation of the IL-10 promoter by tumor necrosis factor-a (TNFa). These results suggest a novel immune regulatory function of Wt1 in controlling IL-10 gene expression.

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These results demonstrate that systemic hypoxia stimulates expression of the TrkB neurotrophin receptor in the airway epithelium. Furthermore, activation of TrkB signalling by BDNF in hypoxia enhances mechanical airway contractility to ACh through a mechanism that requires NO.

Wilms tumor protein 1 (WT1) has been implicated in the control of several genes in sexual development, but its function in gonad formation is still unclear. Here, we report that WT1 stimulates expression of , the gene encoding VEGF receptor 2, in murine embryonic gonads. We found that WT1 and KDR are co-expressed in Sertoli cells of the testes and somatic cells of embryonic ovaries. Vivo-morpholino-mediated WT1 knockdown decreased transcripts in cultured embryonic gonads at multiple developmental stages. Furthermore, WT1 bound to the promoter in the chromatin of embryonic testes and ovaries. Forced expression of the WT1(-KTS) isoform, which functions as a transcription factor, increased mRNA levels, whereas the WT1(+KTS) isoform, which acts presumably on the post-transcriptional level, did not. ChIP indicated that WT1(-KTS), but not WT1(+KTS), binds to the promoter. Treatment with the KDR tyrosine kinase inhibitor SU1498 or the KDR ligand VEGFA revealed that KDR signaling represses the testis-promoting gene in embryonic XX gonads. WT1 knockdown abrogated the stimulatory effect of SU1498-mediated KDR inhibition on expression. Exposure to 1% O to mimic the low-oxygen conditions in the embryo increased expression but did not affect mRNA levels in gonadal explants. However, incubation in 1% O in the presence of SU1498 significantly reduced transcripts in cultured testes and increased levels in ovaries. These findings demonstrate that both the local oxygen environment and WT1, which enhances expression, contribute to sex-specific expression in developing murine gonads.

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