Binding sites for transcription factor Sp1 have been implicated in the transcriptional regulation of several genes by hormones or vitamins, and here we show that a GC-rich element contributes to the retinoic acid response of the interleukin 1beta promoter. To explain such observations, it has been proposed that nuclear receptors can interact with Sp1 bound to GC-rich DNA. However, evidence supp...

BACKGROUND Mitochondria-localized glutamic acid-rich protein (MGARP) is a novel mitochondrial transmembrane protein expressed mainly in steroidogenic tissues and in the visual system. Previous studies showed that MGARP functions in hormone biosynthesis and its expression is modulated by the HPG axis. METHODOLOGY/PRINCIPAL FINDINGS By bioinformatics, we identified two characteristic GC-rich mo...

The transcription factor Sp1 was previously shown to undergo proteasome-dependent degradation when cells were glucose-starved and stimulated with the adenylate cyclase inducer, forskolin. However, the control of the Sp1 degradation process is largely unknown. Using in vitro and in vivo interaction studies, we show in the present study that Sp1 interacts with human Sug1 [hSug1, also known as p45...

Transcription factor Sp1 has been implicated in the expression of many genes. Moreover, it has been suggested that Sp1 is linked to the maintenance of methylation-free CpG islands, the cell cycle, and the formation of active chromatin structures. We have inactivated the mouse Sp1 gene. Sp1-/- embryos are retarded in development, show a broad range of abnormalities, and die around day 11 of gest...

Pancreatic adenocarcinoma is one of the leading causes of cancer-related deaths in the United States. Sp1 is a sequence-specific DNA binding protein that is important in the transcription of a number of regulatory genes involved in cancer cell growth, differentiation, and metastasis. In this study, we investigated Sp1 expression in pancreatic ductal adenocarcinoma and its association with clini...

The process of transcriptional activation in eukaryotes by site-specific DNA-binding proteins is a key step in gene regulation. Here we have examined the properties of four distinct activator domains of the human transcription factor Sp1. In vivo transient cotransfection assays with Sp1 show that templates bearing multiple Sp1 sites activate transcription with a high degree of synergism. Howeve...

Kaposi's sarcoma-associated herpesvirus (KSHV) can be driven into the lytic cycle in vitro by phorbol esters and sodium butyrate. This report begins to analyze the process by which butyrate activates the promoter of KSHV open reading frame 50 (ORF50), the key viral regulator of the KSHV latency to lytic cycle switch. A short fragment of the promoter, 134 nucleotides upstream of the translationa...

Sp1 is a ubiquitous nuclear factor that plays a key role in maintaining basal transcription of 'house-keeping' genes. However, recent evidence points to a more important function for Sp1 in mediating 'cross-talk' between selected signaling cascades to regulate the target genes that respond to these pathways. The role of Sp1 in mediating the actions of the peptide hormone insulin is of specific ...

Previous examination of the effect of TCF-4 on transcription of the human immunodeficiency virus type 1 (HIV-1) promoter in human astrocytic cells found that TCF-4 affects the HIV-1 promoter through the GC-rich domain (nt -80 to nt -68). Here, the physical interaction and a functional consequence of TCF4-Sp1 contact were characterized. It was shown that expression of TCF-4 in U-87 MG (human ast...

Overexpression of DNA 5'-cytosine-methyltransferases (DNMT), which are enzymes that methylate the cytosine residue of CpGs, is involved in many cancers. However, the mechanism of DNMT overexpression remains unclear. Here, we showed that wild-type p53 negatively regulated DNMT1 expression by forming a complex with specificity protein 1 (Sp1) protein and chromatin modifiers on the DNMT1 promoter....