Analysis of LEDGF/p75 expression regulation

Details

Serval ID
serval:BIB_6604C37C61C5
Type
Inproceedings: an article in a conference proceedings.
Publication sub-type
Abstract (Abstract): shot summary in a article that contain essentials elements presented during a scientific conference, lecture or from a poster.
Collection
Publications
Institution
Title
Analysis of LEDGF/p75 expression regulation
Title of the conference
Frontiers of Retrovirology : Complex retroviruses, retroelements and their hosts
Author(s)
Desfarges S., Roulin P., Moraz M.-L., Hernandez-Novoa B., Munoz M., Ciuffi A.
Address
Montpellier, France. 21-23 SEP 2009
ISBN
1742-4690
Publication state
Published
Issued date
2009
Peer-reviewed
Oui
Volume
6
Series
Retrovirology
Pages
-
Language
english
Notes
Meeting Abstract
Abstract
Background To replicate, retroviruses must insert DNA copies of their RNA genomes into the host genome. This integration process is catalyzed by the viral integrase protein. The site of viral integration has been shown to be non-random and retrovirus-specific. LEDGF/p75, a splice variant encoded by PSIP1 gene and described as a general transcription coactivator, was identified as a tethering factor binding both to chromatin and to lentiviral integrases, thereby affecting integration efficiency as well as integration site selection. LEDGF/p75 is still a poorly characterized protein, and its cellular endogenous function has yet to be fully determined. In order to start unveiling the roles of LEDGF/p75 in the cell, we started to investigate the mechanisms involved in the regulation of LEDGF/p75. Materials and methods To identify PSIP1 minimal promoter and associated regulatory elements, we cloned a region starting 5 kb upstream the transcription start site (TSS, +1 reference position) to the ATG start codon (+816), as well as systematic truncations, in a plasmid containing the firefly luciferase reporter gene. These constructs were co-transfected into HEK293 cells with a plasmid encoding the Renilla luciferase under the pTK promoter as an internal control for transfection efficiency. Both luciferase activities were assessed by luminescence as an indicator of promoter activity.
Results Luciferase assays identified regions -76 to +1 and +1 to +94 as two independent minimal promoters showing respectively a 3.7x and 2.3x increase in luciferase activity. These two independent minimal promoters worked synergistically increasing luciferase activity up to 16.3x as compared to background. Moreover, we identified five regulatory blocks which modulated luciferase activity depending on the DNA region tested, three enhancers (- 2007 to -1159, -284 to -171 and +94 to +644) and two silencers (-171 to -76 and +796 to +816). However, the silencing effect of the region -171 to -76 is dependent on the presence of the +94 to +644 region, ruling out the enhancer activity of the latter. Computational analysis of PSIP1 promoter revealed the absence of TATA box and initiator (INR) sequences, classifying this promoter as nonconventional. TATA-less and INR-less promoters are characterized by multiple Sp1 binding sites, involved in the recruitment of the RNA pol II complex. Consistent with this, PSIP1 promoter contains multiple putative Sp1 binding sequences in regions -76 to +1 and +1 to +94.
Web of science
Open Access
Yes
Create date
03/11/2009 11:12
Last modification date
20/08/2019 15:21
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