Transcriptional regulation of the human Sp1 gene promoter by the specificity protein (Sp) family members nuclear factor Y (NF-Y) and E2F

Abstract

We analysed in detail the minimal promoter of transcription factor Sp1, which extends 217 bp from the initiation of transcription. Within this sequence we identified putative binding sites for Sp1, nuclear factor Y (NF-Y), activator protein 2 ('AP-2'), CCAAT/enhancer-binding protein ('C/EBP') and E2F transcription factors. In one case, the boxes for Sp1 and NF-Y are overlapping. Gel-shift and supershift assays demonstrated specific binding of Sp1, Sp3 and NF-Y proteins. Transient transfections and luciferase assays revealed activation of the Sp1 minimal promoter upon overexpression of Sp1 itself, NF-Y and E2F. Whereas overexpression of NF-Y or E2F had an additive effect on Sp1 overexpression, the activation of Sp1 transcription due to Sp1 was counteracted by Sp3 overexpression. Mutagenesis analysis of the NFY/Sp1-overlapping box revealed that both factors compete for this box, and that when the NF-Y site of this overlapping box is specifically mutated there is an increase in Sp1 binding, thus increasing transcriptional activity. These results help to explain the complex regulation of the Sp1 gene, which depends on the relative amounts of Sp1, Sp3, E2F and NF-Y proteins in the cell.

Latent and lytic Epstein‐Barr virus replication strategies

“…There are several putative E2F-binding motifs in the promoters of viral genes such as BRLFI [66], BALF4, BRRF2, BVRF1 and BPLF1 (Kudoh and Tsurumi; unpublished results) besides BALF5 10 10 T. Tsurumi T. Tsurumi et al et al [62]. Also, E2F putative binding sites have been identified within the promoter of the cellular transcription factor Sp1 [67] and E2F exerts an additive effect on its overexpression. Within the EBV lytic gene promoters there are many Sp1 binding sites.…”

Sp1 transcription factor: A long-standing target in cancer chemotherapy

“…Sp1 not only regulates the expression of multiple genes, but also the Sp1 gene itself (Nicolás, et al, 2003;Tapias, et al, 2008). Abnormal Sp1 protein levels have been observed in several cancers Safe, et al, 2014;Sankpal, et al, 2012;Wang, et al, 2003).…”

Loss of Krüppel-Like Factor 4 Expression Contributes to Sp1 Overexpression and Human Gastric Cancer Development and Progression

“…Although a number of studies have reported gene regulation by Sp1, few have reported the transcriptional regulation of Sp1 itself. One recent study showed that the Sp1 promoter contains a number of putative binding sites for several transcription factors, including Sp1, Sp3, nuclear factor Y, activator protein 2, and CCAAT/enhancer-binding protein (13,14). Because the Sp1 promoter contains putative Sp1 binding sites, Sp1 overexpression may result from autotransactivation of its own promoter.…”

“…2C). A previous study reported that a minimal Sp1 promoter (À217 bp upstream of the transcription initiation site) contains binding sites for various transcription factors, including Sp1, nuclear factor Y, activator protein 2, and CCAAT/enhancer-binding protein (13,14). We then tested the effect of KLF4 expression on this minimal Sp1 promoter luciferase reporter.…”