Comprehensive analysis of the renal transcriptional response to acute uranyl nitrate exposure

BACKGROUND: Chemical and radiological toxicities related to uranium acute exposure have been widely studied in nuclear fuel workers and military personnel. It is well known that uranyl nitrate induces acute renal failure (ARF). However, the mechanisms of this metal-induced injury are not well defined at the molecular level. RESULTS: Renal function and histology were assessed in mice receiving uranyl nitrate (UN(+)) and controls (UN(-)). To identify the genomic response to uranium exposure, serial analysis gene expression (SAGE) of the kidney was performed in both groups. Over 43,000 mRNA SAGE tags were sequenced. A selection of the differentially expressed transcripts was confirmed by real-time quantitative PCR and Western blotting. UN(+) animals developed renal failure and displayed the characteristic histological lesions of UN nephropathy. Of the >14,500 unique tags identified in both libraries, 224 had a modified expression level; they are known to participate in inflammation, ion transport, signal transduction, oxidative stress, apoptosis, metabolism, and catabolism. Several genes that were identified had not previously been evaluated within the context of toxic ARF such as translationally controlled tumor protein, insulin like growth factor binding protein 7 and ribosomal protein S29, all apoptosis related genes. CONCLUSION: We report a comprehensive description of the UN induced modifications in gene expression levels, including the identification of genes previously unrelated to ARF. The study of these genes and the metabolisms they control should improve our understanding of toxic ARF and enlighten on the molecular targets for potential therapeutic interventions

Binding of serum response factor to cystic fibrosis transmembrane conductance regulator CArG-like elements, as a new potential CFTR transcriptional regulation pathway

CFTR expression is tightly controlled by a complex network of ubiquitous and tissue-specific cis-elements and trans-factors. To better understand mechanisms that regulate transcription of CFTR, we examined transcription factors that specifically bind a CFTR CArG-like motif we have previously shown to modulate CFTR expression. Gel mobility shift assays and chromatin immunoprecipitation analyses demonstrated the CFTR CArG-like motif binds serum response factor both in vitro and in vivo. Transient co-transfections with various SRF expression vector, including dominant-negative forms and small interfering RNA, demonstrated that SRF significantly increases CFTR transcriptional activity in bronchial epithelial cells. Mutagenesis studies suggested that in addition to SRF other co-factors, such as Yin Yang 1 (YY1) previously shown to bind the CFTR promoter, are potentially involved in the CFTR regulation. Here, we show that functional interplay between SRF and YY1 might provide interesting perspectives to further characterize the underlying molecular mechanism of the basal CFTR transcriptional activity. Furthermore, the identification of multiple CArG binding sites in highly conserved CFTR untranslated regions, which form specific SRF complexes, provides direct evidence for a considerable role of SRF in the CFTR transcriptional regulation into specialized epithelial lung cells