Regulation of expression DLX1 gene, whose elevated levels are detected in patients with acute myeloid leukemia with FLT3-ITD mutations, is not still completely explored topic. The first aim of this study was to determine which selected signaling pathways regulate gene expression of DLX1. ERK a JNK pathways were selected by using qRT-PCR and western blot. These pathways cause activation of the transcription factor AP-1 subunits, the AP-1 putative promoter binding site was identified also in the promoter of the DLX1 gene. The second aim of this study was to test the hypothesis on the regulation of gene expression of DLX1 (via ERK/JNK pathway) through AP-1 binding site on the promoter. Dual luciferase assay using luminescent luciferase activity was performed to test this hypothesis. Gene of the luciferase is contained in the used luciferase vector. The short and the long part of the DLX1 promoter (around AP-1 site) were inserted before the gene of the luciferase in the constructs used in this method. The results of this study indicate that the regulation of gene expression through AP-1 promoter binding site is important but not sufficient part of the regulatory cascade running through ERK and JNK pathway. There must be another transcription factors activated by ERK1/2 kinase which are probably also involved in...

Huntington’s disease (HD) is a neurodegenerative disorder caused by the inheritance of one mutant copy of the huntingtin gene. Mutant huntingtin protein (mHtt) contains an expanded polyglutamine repeat region near the N-terminus. Cleavage of mHtt releases an N-terminal fragment (N-mHtt) which translocates, and accumulates in the nucleus. Nuclear accumulation of N-mHtt has been directly associated with cellular toxicity. Decreased transcription is among the earliest detected changes that occur in the brains of HD patients and is consistently observed in all animal and cellular models of HD. Transcriptional dysregulation may trigger many of the perturbations that occur later in disease progression and an understanding of the effects of mHtt may lead to strategies to slow the progression of the disease. Current models of N-mHtt-mediated transcriptional dysregulation suggest that abnormal interactions between N-mHtt and transcription factors impair the ability of these transcription factors to associate at N-mHtt-affected promoters and properly regulate gene expression. We tested various aspects of these models using two N-mHtt-affected promoters in in vitro transcription assays and in two cell models of HD using techniques including overexpression of known N-mHtt-interacting transcription factors, chromatin immunoprecipitation, promoter deletion and mutation analyses and in vitro promoter binding assays. Based on our results and those in the literature, we proposed a new model of N-mHtt-mediated transcriptional dysregulation centered on the presence of N-mHtt at affected promoters. We concluded that simultaneous interaction of N-mHtt with multiple binding partners within the transcriptional machinery would explain the gene-specificity of N-mHtt-mediated transcriptional dysregulation, as well as the observation that some genes are affected early in disease progression while others are affected later. Our model explains why alleviating N-mHtt-mediated transcriptional dysregulation through overexpression of N-mHtt-interacting proteins has proven to be difficult and suggests that the most realistic strategy for restoring gene expression across the spectrum of N-mHtt affected genes is by reducing the amount of soluble nuclear N-mHtt.