Critical role of hnRNP A1 in activating KRAS transcription in pancreatic cancer cells: A molecular mechanism involving G4 DNA

Cogoi, Susanna; Rapozzi, Valentina; Cauci, Sabina; Xodo, Luigi E.

doi:10.1016/j.bbagen.2016.11.031

Cited by 32 publications

(36 citation statements)

References 78 publications

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“…This seems to induce the recruitment of the transcription factors hnRNP A1 and MAZ and the formation of the transcription pre-initiation complex. Previous studies from our and other laboratories showed that MAZ and hnRNP A1 bind to the promoter G4 region of KRAS and activate transcription [ 22 , 23 , 24 , 25 , 26 , 27 ]. In summary, in this study we have identified a ROS-G4-PARP-1 axis that controls the expression of KRAS under conditions of enhanced oxidative stress.…”

Section: Introductionmentioning

confidence: 99%

Role of Poly [ADP-ribose] Polymerase 1 in Activating the Kirsten ras (KRAS) Gene in Response to Oxidative Stress

Cinque

Ferino

Pedersen

et al. 2020

IJMS

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In pancreatic Panc-1 cancer cells, an increase of oxidative stress enhances the level of 7,8-dihydro-8-oxoguanine (8OG) more in the KRAS promoter region containing G4 motifs than in non-G4 motif G-rich genomic regions. We found that H2O2 stimulates the recruitment to the KRAS promoter of poly [ADP-ribose] polymerase 1 (PARP-1), which efficiently binds to local G4 structures. Upon binding to G4 DNA, PARP-1 undergoes auto PARylation and thus becomes negatively charged. In our view this should favor the recruitment to the KRAS promoter of MAZ and hnRNP A1, as these two nuclear factors, because of their isoelectric points >7, are cationic in nature under physiological conditions. This is indeed supported by pulldown assays which showed that PARP-1, MAZ, and hnRNP A1 form a multiprotein complex with an oligonucleotide mimicking the KRAS G4 structure. Our data suggest that an increase of oxidative stress in Panc-1 cells activates a ROS-G4-PARP-1 axis that stimulates the transcription of KRAS. This mechanism is confirmed by the finding that when PARP-1 is silenced by siRNA or auto PARylation is inhibited by Veliparib, the expression of KRAS is downregulated. When Panc-1 cells are treated with H2O2 instead, a strong up-regulation of KRAS transcription is observed.

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Section: Introductionmentioning

confidence: 99%

Role of Poly [ADP-ribose] Polymerase 1 in Activating the Kirsten ras (KRAS) Gene in Response to Oxidative Stress

Cinque

Ferino

Pedersen

et al. 2020

IJMS

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“…In the promoter of the KRAS oncogene there is a G-rich element called 32R that is critical for transcription and able to fold into a G-quadruplex structure ( 23 ). 32R is located between −148 and −116 bp from transcription start site (TSS) and is recognized by several transcription factors including MAZ and hnRNP A1 ( 24 – 27 ). Polymerase-stop assays, footprinting and circular dichroism showed that 32R is highly polymorphic in nature, as it can fold into three alternative G4 structures ( 28 , 29 ).…”

Section: Introductionmentioning

confidence: 99%

The regulatory G4 motif of the Kirsten ras (KRAS) gene is sensitive to guanine oxidation: implications on transcription

Cogoi

Ferino

Miglietta

et al. 2017

Nucleic Acids Research

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KRAS is one of the most mutated genes in human cancer. It is controlled by a G4 motif located upstream of the transcription start site. In this paper, we demonstrate that 8-oxoguanine (8-oxoG), being more abundant in G4 than in non-G4 regions, is a new player in the regulation of this oncogene. We designed oligonucleotides mimicking the KRAS G4-motif and found that 8-oxoG impacts folding and stability of the G-quadruplex. Dimethylsulphate-footprinting showed that the G-run carrying 8-oxoG is excluded from the G-tetrads and replaced by a redundant G-run in the KRAS G4-motif. Chromatin immunoprecipitation revealed that the base-excision repair protein OGG1 is recruited to the KRAS promoter when the level of 8-oxoG in the G4 region is raised by H2O2. Polyacrylamide gel electrophoresis evidenced that OGG1 removes 8-oxoG from the G4-motif in duplex, but when folded it binds to the G-quadruplex in a non-productive way. We also found that 8-oxoG enhances the recruitment to the KRAS promoter of MAZ and hnRNP A1, two nuclear factors essential for transcription. All this suggests that 8-oxoG in the promoter G4 region could have an epigenetic potential for the control of gene expression.

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“…Interestingly, both G‐quadruplexes and i‐motifs show different regulatory effects. G‐quadruplexes act as transcription inhibitors, whereas, to date, i‐motifs have been postulated to exhibit an activating function . It was further reported that both structures were mutually exclusive in a duplex DNA context, which implied that the formation and function of the G‐quadruplex or the i‐motif could be coordinated by the cell …”

Section: Introductionmentioning

confidence: 99%

Interaction of the N‐Terminal Tandem Domains of hnRNP LL with the BCL2 Promoter i‐Motif DNA Sequence

et al. 2017

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The human genome contains GC-rich sequences able to form tetraplex secondary structures known as the G-quadruplex and i-motif. Such sequences are notably present in the promoter region of oncogenes and are proposed to function as regulatory elements of gene expression. The P1 promoter of BCL2 contains a 39-mer C-rich sequence (Py39wt) that can fold into a hairpin or an i-motif in a pH-dependent manner in vitro. The protein hnRNP LL was identified to recognise the i-motif over the hairpin conformation and act as an activating transcription factor. Thus, the Py39wt sequence would act as an ON/OFF switch, according to the secondary structure adopted. Herein, a structural study of the interaction between hnRNP LL and Py39wt is reported. Both N-terminal RNA recognition motifs (RRM12) cooperatively recognise one Py39wt DNA sequence and engage their β-sheet to form a large binding platform. In contrast, the C-terminal RRMs show no binding capacity. It is observed that RRM12 binds to Py39wt regardless of the DNA conformation. We propose that RRM12 recognises a single-stranded CTCCC element present in loop 1 of the i-motif and in the apical loop of the hairpin conformation.

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Critical role of hnRNP A1 in activating KRAS transcription in pancreatic cancer cells: A molecular mechanism involving G4 DNA

Cited by 32 publications

References 78 publications

Role of Poly [ADP-ribose] Polymerase 1 in Activating the Kirsten ras (KRAS) Gene in Response to Oxidative Stress

Role of Poly [ADP-ribose] Polymerase 1 in Activating the Kirsten ras (KRAS) Gene in Response to Oxidative Stress

The regulatory G4 motif of the Kirsten ras (KRAS) gene is sensitive to guanine oxidation: implications on transcription

Interaction of the N‐Terminal Tandem Domains of hnRNP LL with the BCL2 Promoter i‐Motif DNA Sequence

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