No abstract

The rat aldolase B 5' flanking region (nucleotides - 194 to +41) contains sufficient information for liver-specific expression. A detailed investigation of factors binding to the rat aldolase B 5' flanking region has allowed us to identify three distinct factors that filled different sites of this region (A, B, C). The liver-enriched C/EBP or related factors bind to box C, as demonstrated by the specific interaction with bacterially expressed C/EBP protein. Box B bearing the CCAAT sequence binds the ubiquitous factor NFY. Surprisingly, Box A is able to bind two liver enriched factors, namely HNF1 and HNF3. However, in the context of the intact promoter, as shown by footprinting competition experiments, HNF3 binds solely to this sequence. HNF3, but not HNF1 is a transcriptional activator as demonstrated in the in vitro transcription assay.

The majority of patients with epilepsy maintain seizure control during pregnancy. The apparently higher risk of seizures among women treated with oxcarbazepine and the more frequent increases in drug load in the oxcarbazepine and lamotrigine cohorts prompts further studies on relationships with pharmacokinetic changes. Risks associated with status epilepticus appear to be lower than previously reported.

The aldolase B proximal promoter is controlled by at least five elements spanning from -190 to -103 bp with respect to the start site of transcription. From 5' to 3', we found: a negative DE element, an activating C/EBP-DBP binding site, a CCAAT box binding NFY that seems to play a negative role, and an activating element consisting of two overlapping binding sites for HNF-1 and HNF-3. Contransfection experiments of aldolase B/CAT constructs and of expression vectors for different transcription factors were carried out in human hepatoma Hep G2 cells. We found that DBP and HNF-1 are strong transactivators of the aldolase B promoter while C/EBP and vHNF-1 are only weak activators and HNF-3 alone does not modify such activity. Deletion of the distal negative element results in a similar transactivation by C/EBP and DBP, enhanced for the former and reduced for the latter. In hepatocytes in primary culture, the strong transactivator is C/EBP while DBP is essentially inactive. This tissue-specificity of C/EBP and DBP action could depend on interaction with tissue-specific proteins bound to a neighbouring site, probably DE. Finally, HNF3 behaves as a very strong anti-activator of the aldolase B promoter. It competitively antagonizes transactivation by HNF-1 and non-competitively transactivation by DBP. This negative effect of HNF-3 and tissue-specificity of the transactivation potential of DBP and C/EBP are unique features of the aldolase B promoter.