Transcriptional Protein Sp1 Regulates LEDGF Transcription by Directly Interacting with Its Cis-Elements in GC-Rich Region of TATA-Less Gene PromoterReportar como inadecuado




Transcriptional Protein Sp1 Regulates LEDGF Transcription by Directly Interacting with Its Cis-Elements in GC-Rich Region of TATA-Less Gene Promoter - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

LEDGF-p75 interacts with DNA-protein to regulate gene expression and function. Despite the recognized diversity of function of LEDGF-p75, knowledge of its transregulation is in its infancy. Here we report that LEDGF-p75 gene is TATA-less, contains GC-rich cis elements and is transcriptionally regulated by Sp1 involving small ubiquitin-like modifier Sumo1. Using different cell lines, we showed that Sp1 overexpression increased the level of LEDGF-p75 protein and mRNA expression in a concentration-dependent fashion. In contrast, RNA interference depletion of intrinsic Sp1 or treatment with artemisinin, a Sp1 inhibitor, reduced expression of LEDGF-p75, suggesting Sp1-mediated regulation of LEDGF-p75. In silico analysis disclosed three evolutionarily conserved, putative Sp1 sites within LEDGF-p75 proximal promoter −170-+1 nt. DNA-binding and transactivation assays using deletion and point mutation constructs of LEDGF-p75 promoter-CAT revealed that all Sp1 sites −50-−43, −109-−102 and −146-−139 differentially regulate LEDGF-p75. Cotransfection studies with Sp1 in Drosophila cells that were Sp1-deficient, showed increased LEDGF-p75 transcription, while in lens epithelial cells LECs promoter activity was inhibited by artemisinin. These events were correlated with levels of endogenous Sp1-dependent LEDGF-p75 expression, and higher resistance to UVB-induced cell death. ChIP and transactivation assays showed that Sumoylation of Sp1 repressed its transcriptional activity as evidenced through its reduced binding to GC-box and reduced ability to activate LEDGF-p75 transcription. As whole, results revealed the importance of Sp1 in regulating expression of LEDGF-p75 gene and add to our knowledge of the factors that control LEDGF-p75 within cellular microenvironments, potentially providing a foundation for LEDGF-p75 expression-based transcription therapy.



Autor: Dhirendra P. Singh , Biju Bhargavan, Bhavana Chhunchha, Eri Kubo, Anil Kumar, Nigar Fatma

Fuente: http://plos.srce.hr/



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