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Báo cáo khoa học: Interactions of HIPPI, a molecular partner of Huntingtin interacting protein HIP1, with the specific motif present at the putative promoter sequence of the caspase-1, caspase-8 and caspase-10 genes

To investigate the mechanism of increased expression of caspase-1 caused by exogenousHippi, observed earlier in HeLa and Neuro2A cells, in this work we identified a specific motif AAAGACATG ()101 to)93) at the caspase-1 gene upstream sequence where HIPPI could bind. Various muta-tions in this specific sequence compromised the interaction, showing the specificity of the interactions. | ễFEBS Journal Interactions of HIPPI a molecular partner of Huntingtin interacting protein HIP1 with the specific motif present at the putative promoter sequence of the caspase-1 caspase-8 and caspase-10 genes P. Majumder1 A. Choudhury2 M. Banerjee1 A. Lahiri2 and N. P. Bhattacharyya1 1 StructuralGenomics Section Saha Institute of Nuclear Physics Bidhan Nagar Kolkata India 2 Department of Biophysics Molecular Biology and Genetics University of Calcutta Kolkata India Keywords caspase HIPPI motif pDED transcription regulation Correspondence N. P. Bhattacharyya StructuralGenomics Section Saha Institute of Nuclear Physics 1 AF Bidhan Nagar Kolkata 700 064 India Fax 91 033 2337 4637 Tel 91 033 2337 5345 E-mail nitai_sinp@yahoo.com Received 11 April2007 revised 1 June 2007 accepted 5 June 2007 doi 10.1111 j.1742-4658.2007.05922.x To investigate the mechanism of increased expression of caspase-1 caused by exogenous Hippi observed earlier in HeLa and Neuro2A cells in this work we identified a specific motif AAAGACATG - 101 to - 93 at the caspase-1 gene upstream sequence where HIPPI could bind. Various mutations in this specific sequence compromised the interaction showing the specificity of the interactions. In the luciferase reporter assay when the reporter gene was driven by caspase-1 gene upstream sequences - 151 to - 92 with the mutation G to T at position - 98 luciferase activity was decreased significantly in green fluorescent protein-Hippi-expressing HeLa cells in comparison to that obtained with the wild-type caspase-1 gene 60 bp upstream sequence indicating the biological significance of such binding. It was observed that the C-terminal pseudo death effector domain of HIPPI interacted with the 60 bp - 151 to - 92 upstream sequence of the caspase-1 gene containing the motif. We further observed that expression of caspase-8 and caspase-10 was increased in green fluorescent protein-Hippi-expressing HeLa cells. In addition HIPPI interacted in vitro with putative .