Nuclear Factor 1 Interferes with Sp1 Binding through a Composite Element on the Rat Poly(ADP-ribose) Polymerase Promoter to Modulate Its Activity in Vitro

Abstract

Poly(ADP-ribose) polymerase-1 (PARP-1) catalyzes the rapid and extensive poly(ADP-ribosyl)ation of nuclear proteins in response to DNA strand breaks, and its expression, although ubiquitous, is modulated from tissue to tissue and during cellular differentiation. PARP-1 gene promoters from human, rat, and mouse have been cloned, and they share a structure common to housekeeping genes, as they lack a functional TATA box and contain multiple GC boxes, which bind the transcriptional activator Sp1. We have previously shown that, although Sp1 is important for rat PARP1 (rPARP) promoter activity, its finely tuned modulation is likely dependent on other transcription factors that bind the rPARP proximal promoter in vitro. In this study, we identified one such factor as NF1-L, a rat liver isoform of the nuclear factor 1 family of transcription factors. The NF1-L site on the rPARP promoter overlaps one of the Sp1 binding sites previously identified, and we demonstrated that binding of both factors to this composite element is mutually exclusive. Furthermore, we provide evidence that NF1-L has no effect by itself on rPARP promoter activity, but rather down-regulates the Sp1 activity by interfering with its ability to bind the rPARP promoter in order to modulate transcription of the rPARP gene.Poly(ADP-ribose) polymerase-1 (PARP-1) 1 is a nuclear enzyme which catalyzes the addition of ADP-ribose units from nicotinamide adenine dinucleotide (NAD ϩ ) onto itself and other nuclear proteins such as histones and topoisomerases (reviewed in Refs. 1 and 2). It is made up of three functional domains, namely the amino-terminal DNA-binding domain, the central automodification domain, and the carboxyl-terminal catalytic domain (3). Although PARP-1 is often associated with DNA repair, because of its rapid and extensive activation following DNA damage (4, 5), it has also been implicated in other major nuclear functions such as transcription (6, 7), DNA replication (8, 9) and recombination (10). PARP-1 is also important for cell differentiation (11-13) and is involved in cell death, likely acting as a molecular switch between apoptosis and necrosis (14).PARP-1 is expressed in all organs, albeit at varying degrees, with highest mRNA expression found in brain, thymus, heart, and testis (15, 16). PARP-1 mRNA level is regulated at the cell cycle level, reaching its peak at either the G 1 (17-20) or the S phases (21, 22). It has also been shown that a decrease in PARP-1 mRNA levels is associated with cellular differentiation (23-26) and senescence (27), whereas an increase is observed upon activation of lymphocytes (17, 28) or peripheral blood mononuclear cells (18). All these studies show that, although PARP-1 is ubiquitously expressed, its modulation, likely through complex transcriptional regulation, is critical to major cellular functions.In order to better understand the transcriptional mechanisms regulating PARP-1 expression, the PARP-1 gene promoter has been identified and cloned from three mammalian species, human (29, 30), rat (31), ...

Identification of a region in the human IRS2 promoter essential for stress induced transcription depending on SP1, NFI binding and ERK activation in HepG2 cells

“…We assumed that NFI might function as a repressor of the IRS2 gene promoter that would interfere with the activator function of SP1 as it has been described for the poly(ADP-ribose) polymerase-1 promoter (Laniel et al 2001) or the platelet-derived growth factor A promoter (Rafty et al 2002). However, our experiments prove that SP1 or NFI binding is sufficient to activate the promoter.…”

FASN regulates cellular response to genotoxic treatments by increasing PARP-1 expression and DNA repair activity via NF-κB and SP1

“…6A). Previously, it has been shown that the rat PARP-1 gene is activated by SP1 (17) and inactivated by NF1, which competes with SP1 on a composite element in the promoter of rat PARP-1 (18). We have also shown that FASN down-regulates NF-κB expression (4).…”

Rescue of the Transcription Factors Sp1 and NFI in Human Skin Keratinocytes through a Feeder-Layer-Dependent Suppression of the Proteasome Activity

“…27,28 However, unlike Sp1 that is unquestionably recognized as a TF that positively influences gene transcription (reviewed in Ref. 29), members from the NFI family have been reported to be as efficient as repressors 30,31 than as activators 32 of gene transcription.…”