Project description:Insults to cellular health cause p53 protein accumulation and loss of p53 function leads to tumorigenesis. Thus, p53 has to be tightly controlled. Here we report that the BTB/POZ domain transcription factor PATZ1 (MAZR), previously known for its transcriptional suppressor functions in T lymphocytes, is a crucial regulator of p53. The novel inhibitory role of PATZ1 on the p53 protein marks it as a proto-oncogene. PATZ1 deficient cells have reduced proliferative capacity which we assess by RNASeq and real time cell growth rate analysis. PATZ1 modifies the expression of p53 target genes associated with cell proliferation gene ontology terms. Moreover, PATZ1 regulates several genes involved in cellular adhesion and morphogenesis. Significantly, treatment with the DNA damage inducing drug doxorubicin results in the loss of the PATZ1 transcription factor, as p53 accumulates. We find that PATZ1 binds to p53 and inhibits p53 dependent transcription activation. We examine the mechanism of this functional inhibitory interaction and demonstrate that PATZ1 excludes p53 from DNA binding. This study documents PATZ1 as a novel player in the p53 pathway. RNA-seq was used to define differentially expressed genes in wild-type and PATZ1-/- MEFs. Each sample was represented in triplicate.
Project description:Insults to cellular health cause p53 protein accumulation and loss of p53 function leads to tumorigenesis. Thus, p53 has to be tightly controlled. Here we report that the BTB/POZ domain transcription factor PATZ1 (MAZR), previously known for its transcriptional suppressor functions in T lymphocytes, is a crucial regulator of p53. The novel inhibitory role of PATZ1 on the p53 protein marks it as a proto-oncogene. PATZ1 deficient cells have reduced proliferative capacity which we assess by RNASeq and real time cell growth rate analysis. PATZ1 modifies the expression of p53 target genes associated with cell proliferation gene ontology terms. Moreover, PATZ1 regulates several genes involved in cellular adhesion and morphogenesis. Significantly, treatment with the DNA damage inducing drug doxorubicin results in the loss of the PATZ1 transcription factor, as p53 accumulates. We find that PATZ1 binds to p53 and inhibits p53 dependent transcription activation. We examine the mechanism of this functional inhibitory interaction and demonstrate that PATZ1 excludes p53 from DNA binding. This study documents PATZ1 as a novel player in the p53 pathway.
Project description:Insults to cellular health cause p53 protein accumulation and loss of p53 function leads to tumorigenesis. Thus, p53 has to be tightly controlled. Here we report that the BTB/POZ domain transcription factor PATZ1 (MAZR), previously known for its transcriptional suppressor functions in T lymphocytes, is a crucial regulator of p53. The novel inhibitory role of PATZ1 on the p53 protein marks it as a proto-oncogene. PATZ1 deficient cells have reduced proliferative capacity which we assess by RNASeq and real time cell growth rate analysis. PATZ1 modifies the expression of p53 target genes associated with cell proliferation gene ontology terms. Moreover, PATZ1 regulates several genes involved in cellular adhesion and morphogenesis. Significantly, treatment with the DNA damage inducing drug doxorubicin results in the loss of the PATZ1 transcription factor, as p53 accumulates. We find that PATZ1 binds to p53 and inhibits p53 dependent transcription activation. We examine the mechanism of this functional inhibitory interaction and demonstrate that PATZ1 excludes p53 from DNA binding. This study documents PATZ1 as a novel player in the p53 pathway.
2017-07-29 | GSE71529 | GEO
Project description:PATZ1 is a DNA damage responsive transcription factor that inhibits p53 function [with and without doxorubicin treatment]
Project description:The goal of this experiment was to determine the role of the lncRNA DINO in the DNA damage response in regulating transcription factor occupancy of human fibroblasts. DINO, an inducible long noncoding in respose to DNA damage, is required for cell cycle arrest and induction of several p53 regulated genes. We hypothesized that ATACseq in DINO-depleted cells may uncover a role for DINO in transcription factor recruitment to p53 responsive genes following DNA damage.
Project description:Integrated-systems model of oxidative stress connecting NRF2 and p53 signaling pathways. Additional crosstalk linking oxidative stress to p53 inhibition, p53 to NRF2 through p21, and NRF2 to MDM2 was incorporated in this model. The NRF2 pathway was encoded as first- and second-order rate equations for KEAP1 oxidation and NRF2 stabilization; NRF2-mediated transcription of antioxidant enzymes was modeled as a Hill function. The p53 pathway was reconstructed from a delay differential equation model of p53 signaling in response to DNA damage. To adapt the p53 DNA-damage model to respond to oxidative stress, we used a first-order oxidation reaction of ATM/CHEK2 by intracellular H2O2.
The integrated base model of NRF2–p53 oxidative-stress signaling contains 42 reactions and 22 ordinary differential equations (ODEs).
Project description:Liver cancer is the third most common cause of cancer death in the world. POZ/BTB and AT-hook-containing zinc finger protein 1 (PATZ1) is a transcription factor associated with various cancers. However, the role of PATZ1 in cancer progression remains controversial. Here we report that PATZ1 regulates cell proliferation by directly regulating CDKN1B (p27) in hepatocellular carcinoma HepG2 cells. PATZ1 level was found to be ectopically expressed in hepatocellular carcinoma cells compared to normal primary human hepatocytes, thus affirming its relevance in liver cancer. Our gene expression microarray and PATZ1 ChIP-seq analysis further revealed strong enrichment in gene ontology terms related to cellular proliferation. Importantly, siRNA-mediated PATZ1 knockdown in HepG2 cells led to an increased rate of colony formation, elevated Ki-67 expression and greater S phase entry. Furthermore, the increased cancer cell proliferation was accompanied with suppressed expression of the cyclin-dependent kinase inhibitor CDKN1B. Consistently, PATZ1 binds to the genomic loci flanking the transcriptional start site of CDKN1B and positively regulates its promoter activity. Additionally, we found that PATZ1 associates with p53 and the absence of p53 abrogated the PATZ1-mediated regulation of CDKN1B expression. In conclusion, our study provides novel mechanistic insights into the role of PATZ1 in liver cancer progression, thereby providing a promising therapeutic intervention to alleviate tumor burden in liver cancer.
Project description:Liver cancer is the third most common cause of cancer death in the world. POZ/BTB and AT-hook-containing zinc finger protein 1 (PATZ1) is a transcription factor associated with various cancers. However, the role of PATZ1 in cancer progression remains controversial. Here we report that PATZ1 regulates cell proliferation by directly regulating CDKN1B (p27) in hepatocellular carcinoma HepG2 cells. PATZ1 level was found to be ectopically expressed in hepatocellular carcinoma cells compared to normal primary human hepatocytes, thus affirming its relevance in liver cancer. Our gene expression microarray and PATZ1 ChIP-seq analysis further revealed strong enrichment in gene ontology terms related to cellular proliferation. Importantly, siRNA-mediated PATZ1 knockdown in HepG2 cells led to an increased rate of colony formation, elevated Ki-67 expression and greater S phase entry. Furthermore, the increased cancer cell proliferation was accompanied with suppressed expression of the cyclin-dependent kinase inhibitor CDKN1B. Consistently, PATZ1 binds to the genomic loci flanking the transcriptional start site of CDKN1B and positively regulates its promoter activity. Additionally, we found that PATZ1 associates with p53 and the absence of p53 abrogated the PATZ1-mediated regulation of CDKN1B expression. In conclusion, our study provides novel mechanistic insights into the role of PATZ1 in liver cancer progression, thereby providing a promising therapeutic intervention to alleviate tumor burden in liver cancer.
Project description:P53 inactivation occurs in about 50% of human cancers, where p53-driven p21 activity is devoid and p27 becomes essential for the establishment of the G1/S checkpoint upon DNA damage. Here, we show that the E2F1-responsive lncRNA LIMp27 selectively represses p27 expression and contributes to proliferation, tumorigenicity, and treatment resistance in p53-defective colon adenocarcinoma (COAD) cells. LIMp27 competes with p27 mRNA for binding to cytoplasmically localized hnRNA0, which otherwise stabilizes p27 mRNA leading to cell cycle arrest at the G0/G1 phase. In response to DNA damage, LIMp27 is upregulated in both wild-type and p53-mutant COAD cells, whereas cytoplasmic hnRNPA0 is only increased in p53-mutant COAD cells due to translocation from the nucleus. Moreover, high LIMp27 expression is associated with poor survival of p53-mutant but not wild-type p53 COAD patients. These results uncover a lncRNA mechanism that promotes p53-defective cancer pathogenesis and suggest that LIMp27 may constitute a target for the treatment of such cancers.
Project description:After DNA damage, cells activate p53, a tumor suppressor gene, and select a cell fate (e.g., DNA repair, cell cycle arrest, or apoptosis). Recently, a p53 oscillatory behavior was observed following DNA damage. However, the relationship between this p53 oscillation and cell-fate selection is unclear. Here, we present a novel model of the DNA damage signaling pathway that includes p53 and whole cell cycle regulation and explore the relationship between p53 oscillation and cell fate selection. The simulation run without DNA damage qualitatively realized experimentally observed data from several cell cycle regulators, indicating that our model was biologically appropriate. Moreover, the comprehensive sensitivity analysis for the proposed model was implemented by changing the values of all kinetic parameters, which revealed that the cell cycle regulation system based on the proposed model has robustness on a fluctuation of reaction rate in each process. Simulations run with four different intensities of DNA damage, i.e. Low-damage, Medium-damage, High-damage, and Excess-damage, realized cell cycle arrest in all cases. Low-damage, Medium-damage, High-damage, and Excess-damage corresponded to the DNA damage caused by 100, 200, 400, and 800 J/m(2) doses of UV-irradiation, respectively, based on expression of p21, which plays a crucial role in cell cycle arrest. In simulations run with High-damage and Excess-damage, the length of the cell cycle arrest was shortened despite the severe DNA damage, and p53 began to oscillate. Cells initiated apoptosis and were killed at 400 and 800 J/m(2) doses of UV-irradiation, corresponding to High-damage and Excess-damage, respectively. Therefore, our model indicated that the oscillatory mode of p53 profoundly affects cell fate selection.