Activation of Vascular Endothelial Growth Factor A Transcription in Tumorigenic Glioblastoma Cell Lines by an Enhancer with Cell Type-specific DNase I Accessibility

Liang, Yuxin; Li, Xiaoyong; Rebar, Edward J.; Pei-xiang, LI; Zhou, Yuanyue; Chen, Bingliang; Wolffe, Alan P.; Case, Casey C.

doi:10.1074/jbc.m201766200

Cited by 29 publications

(20 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The only exception was represented by A172. These cells have been already reported to be non-tumorigenic (Ridder et al , 1987; Liang et al , 2002; Cerchia et al , 2009). Our data show that in A172 cells PTPμ expression is low even in the presence of low miR-221 levels.…”

Section: Resultsmentioning

confidence: 91%

miR-221/222 overexpession in human glioblastoma increases invasiveness by targeting the protein phosphate PTPμ

et al. 2011

View full text Add to dashboard Cite

Glioblastoma is the most frequent brain tumor in adults and is the most lethal form of human cancer. Despite the improvements in treatments, survival of patients remains poor. In order to identify microRNAs (miRs) involved in glioma tumorigenesis, we evaluated, by a miRarray, differential expression of miRs in the tumorigenic glioma LN-18, LN-229 and U87MG cells compared with the non-tumorigenic T98G cells. Among different miRs we focused our attention on miR-221 and -222. We demonstrated the presence of a binding site for these two miRs in the 3′ untranslated region of the protein tyrosine phosphatase μ (PTPμ). Previous studies indicated that PTPμ suppresses cell migration and is downregulated in glioblastoma. Significantly, we found that miR-221 and -222 over-expression induced a downregulation of PTPμ as analyzed by both western blot and real-time PCR. Furthermore, miR-222 and -221 induced an increase in cell migration and growth in soft agar in glioma cells. Interestingly, the re-expression of PTPμ gene was able to revert the miR-222 and -221 effects on cell migration. Furthermore, we found an inverse correlation between miR-221 and -222 and PTPμ in human glioma cancer samples. In conclusion, our results suggest that miR-221 and -222 regulate glioma tumorigenesis at least in part through the control of PTPμ protein expression.

show abstract

Section: Resultsmentioning

confidence: 91%

miR-221/222 overexpession in human glioblastoma increases invasiveness by targeting the protein phosphate PTPμ

et al. 2011

View full text Add to dashboard Cite

show abstract

“…Accordingly, the distribution of regions accessible to DNase I in the promoter of the VEGF-A locus appeared to be specific to the cell type and was essential in the design of TF ZF s targeting VEGF-A. 9,27 The differences in activity may also reflect variations in the availability of interacting accessory factors among cell types and their localization on the chromosomes. Accordingly, complex regulation mechanisms involving abundant signaling pathways and transcription factors in ICAM-1 expression have been revealed to be cell-type specific.…”

Section: Discussionmentioning

confidence: 99%

In Vivo Selection of Combinatorial Libraries and Designed Affinity Maturation of Polydactyl Zinc Finger Transcription Factors for ICAM-1 Provides New Insights into Gene Regulation

Magnenat

Blancafort

Barbas

2004

Journal of Molecular Biology

View full text Add to dashboard Cite

Zinc finger DNA-binding domains can be combined to create new proteins of desired DNA-binding specificity. By shuffling our repertoire of modified zinc finger domains to create randomly generated polydactyl zinc finger proteins with transcriptional regulatory domains, we developed large combinatorial libraries of zinc finger transcription factors (TF ZF s). Millions of TF ZF s can then be simultaneously screened in mammalian cells. Here, we successfully isolated specific TF ZF s that significantly positively and negatively modulate the transcription of the ICAM-1 gene in primary and cancer cells, which are relevant to ICAM-1 biology and tumor development. We show that TF ZF s can work in a general and in a cell-type specific manner depending on the regulatory domain and the zinc finger protein. We show that a TF ZF that interacts directly with the ICAM-1 promoter at an overlapping NF-kB binding enhancer can overcome or synergistically cooperate with NF-kB induction of ICAM-1. For this TF ZF , rational design was used to optimize the binding of the zinc finger protein to its DNA element and the resulting TF ZF demonstrated a direct correlation between increased affinity and efficiency of target gene regulation. Thus, combining library and affinity maturation approaches generated superior TF ZF s that may find further applications in therapeutic research and in ICAM-1 biology, and also provided novel mechanistic insights into the biology of transcription factors. Transcription factor libraries provide genome-wide approaches that can be applied towards the development of TF ZF s specific for virtually any gene or desired phenotype and may lead to the discovery of new genetic functions and pathways.

show abstract

“…Human HEK293 nuclei were treated with DNase I as described (17). Genomic DNA isolation, restriction enzyme digestion, and Southern blot analysis were then carried out as described (5,7) except that the restriction enzymes and probe used were as indicated in Fig.…”

Section: Mapping Of Dnase I-accessible Chromatin Regions In Chk2 Locusmentioning

confidence: 99%

Zinc-finger protein-targeted gene regulation: Genomewide single-gene specificity

Tan

Guschin

Davalos

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

138

126

View full text Add to dashboard Cite

Zinc-finger protein transcription factors (ZFP TFs)D efects in transcriptional regulation underlie numerous disease states, most notably cancer (1). A major goal of current strategies for correcting such defects is to achieve sufficient specificity of action (2). Designed zinc-finger protein transcription factors (ZFP TFs) emulate natural transcriptional control mechanisms and therefore provide an attractive tool for precisely regulating gene expression. Accurate control of gene expression is important for understanding gene function (target validation) and for developing therapeutics to treat disease (3). We and others have used engineered ZFP TFs to either activate or repress a variety of endogenous gene targets (4-11). For these proteins, or any other gene-regulation technology, to succeed as tools in drug discovery or direct agents in the clinic, their specificity of action within the genome must be precise, a challenging criterion to meet given the size and complexity of the human genome. Recent studies with small interfering RNA (12, 13) and antisense DNA͞RNA (14) have illuminated the magnitude of the task of achieving single-gene specificity in regulating the human genome.We focus here on the use of ZFP TFs in the area of oncology and specifically on the emerging role of checkpoint kinase 2 (CHK2). CHK2 acts as a key integrator of DNA-damage signals regulating cell-cycle progression, DNA repair, and cell death by phosphorylating a variety of substrates, including the p53 tumor suppressor protein (15, 16). Here we show that a designed ZFP TF targeted to a unique 18-bp recognition sequence in the promoter of the CHK2 gene binds the intended site within chromatin and represses CHK2 transcription in vivo. Moreover, repression of CHK2 by this engineered ZFP TF occurs with remarkable specificity, while simultaneously reducing CHK2 protein to levels that functionally ablate the action of this kinase. Finally, we show that constitutive expression of the ZFP TF in telomerase-immortalized, untransformed human fibroblasts provides stable repression of the CHK2 gene and results in loss of DNA-damage-induced CHK2-dependent phosphorylation of p53 on Ser-20. These data demonstrate that ZFP TFs can be exquisitely specific, yet potent repressors of gene expression and, therefore, are potentially powerful reagents for target validation and therapeutic interventions in vivo.

show abstract

Activation of Vascular Endothelial Growth Factor A Transcription in Tumorigenic Glioblastoma Cell Lines by an Enhancer with Cell Type-specific DNase I Accessibility

Cited by 29 publications

References 35 publications

miR-221/222 overexpession in human glioblastoma increases invasiveness by targeting the protein phosphate PTPμ

miR-221/222 overexpession in human glioblastoma increases invasiveness by targeting the protein phosphate PTPμ

In Vivo Selection of Combinatorial Libraries and Designed Affinity Maturation of Polydactyl Zinc Finger Transcription Factors for ICAM-1 Provides New Insights into Gene Regulation

Zinc-finger protein-targeted gene regulation: Genomewide single-gene specificity

Contact Info

Product

Resources

About