Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Edwin Zwart is active.

Publication


Featured researches published by Edwin Zwart.


Molecular and Cellular Biology | 2004

Increased Sensitivity to UV Radiation in Mice with a p53 Point Mutation at Ser389

Wendy Bruins; Edwin Zwart; Laura D. Attardi; Tomoo Iwakuma; Esther M. Hoogervorst; Rudolf B. Beems; Barbara Miranda; Conny T. M. van Oostrom; Jolanda van den Berg; Gerard van den Aardweg; Guillermina Lozano; Harry van Steeg; Tyler Jacks; Annemieke de Vries

ABSTRACT Phosphorylation is important for p53 protein stabilization and activation after DNA damage. Serine 389 of p53 is specifically phosphorylated after UV irradiation, whereas gamma radiation activates p53 through a different pathway. To study the in vivo significance of p53 phosphorylation at serine 389, we generated a physiological mouse model in which p53 phosphorylation at serine 389 is abolished by alanine substitution. Homozygous mutant p53.S389A mice are viable and have an apparently normal phenotype. However, cells isolated from these mice are partly compromised in transcriptional activation of p53 target genes and apoptosis after UV irradiation, whereas gamma radiation-induced responses are not affected. Moreover, p53.S389A mice show increased sensitivity to UV-induced skin tumor development, signifying the importance of serine 389 phosphorylation for the tumor-suppressive function of p53.


Nanotoxicology | 2011

Genotoxicity evaluation of amorphous silica nanoparticles of different sizes using the micronucleus and the plasmid lacZ gene mutation assay

Margriet V. D. Z. Park; Henny W. Verharen; Edwin Zwart; Lya G. Hernández; Jan van Benthem; Andreas Elsaesser; Clifford Barnes; George McKerr; C. Vyvyan Howard; Anna Salvati; Iseult Lynch; Kenneth A. Dawson; Wim H. de Jong

Abstract We investigated the potential of four well-characterized amorphous silica nanoparticles to induce chromosomal aberrations and gene mutations using two in vitro genotoxicity assays. Transmission electron microscopy (TEM) was used to verify the manufacturers nominal size of 10, 30, 80 and 400 nm which showed actual sizes of 11, 34, 34 and 248 nm, respectively. The 80 (34) nm silica nanoparticles induced chromosomal aberrations in the micronucleus assay using 3T3-L1 mouse fibroblasts and the 30 (34) and 80 (34) nm silica nanoparticles induced gene mutations in mouse embryonic fibroblasts carrying the lacZ reporter gene. TEM imaging demonstrated that the majority of nanoparticles were localized in vacuoles and not in the nucleus of 3T3-L1 cells, indicating that the observed DNA damage was most likely a result of indirect mechanisms. Further studies are needed to reveal these mechanisms and to determine the biological relevance of the effects of these particular silica nanoparticles in vivo.


Cancer Research | 2005

Mice Expressing a Mammary Gland–Specific R270H Mutation in the p53 Tumor Suppressor Gene Mimic Human Breast Cancer Development

Susan W.P. Wijnhoven; Edwin Zwart; Ewoud N. Speksnijder; Rudolf B. Beems; Kenneth P. Olive; David A. Tuveson; Jos Jonkers; Mirjam M. Schaap; Jolanda van den Berg; Tyler Jacks; Harry van Steeg; Annemieke de Vries

The tumor suppressor gene p53 has an apparent role in breast tumor development in humans, as approximately 30% of sporadic tumors acquire p53 mutations and Li-Fraumeni syndrome patients carrying germ line p53 mutations frequently develop breast tumors at early age. In the present study, conditional expression of a targeted mutation is used to analyze the role of the human R273H tumor-associated hotspot mutation in p53 in mammary gland tumorigenesis. Heterozygous p53(R270H/+)WAPCre mice (with mammary gland-specific expression of the p53.R270H mutation, equivalent to human R273H, at physiologic levels) develop mammary tumors at high frequency, indicating that the R270H mutation predisposes for mammary gland tumor development and acts in a dominant-negative manner in early stages of tumorigenesis. Spontaneous tumor development in these mice is further accelerated by 7,12-dimethylbenz(a)anthracene (DMBA) treatment at young age. The majority of spontaneous and DMBA-induced carcinomas and sarcomas from p53(R270H/+)WAPCre mice is estrogen receptor alpha positive, and expression profiles of genes also implicated in human breast cancer appear similarly altered. As such, p53(R270H/+)WAPCre mice provide a well-suited model system to study the role of p53 in breast tumorigenesis and the responsiveness of mammary gland tumors to chemotherapeutics.


Reproductive Toxicology | 2010

Proteome profiling of mouse embryonic stem cells to define markers for cell differentiation and embryotoxicity

Ahmed M. Osman; Dorien A.M. van Dartel; Edwin Zwart; Marco Blokland; Jeroen L. A. Pennings; Aldert H. Piersma

In search for alternative methods for developmental toxicity testing, we investigated whether embryonic stem cell (ESC) differentiation and its modulation by toxic exposure could be monitored by proteome profiling. We compared the proteomes of mouse ESC, differentiating ESC (DIF) and differentiating ESC exposed to the embryotoxicant monobutyl phthalate (MBP). Experiments were performed in duplicates for each cell culture and the proteins extracted from the cells were separated by one-dimensional SDS-PAGE. The identified proteins were quantified using a label-free quantitative method based on counting the observed peptides as an index of protein abundance. Fifty-seven proteins were upregulated in DIF relative to ESC, whereas 42 proteins were downregulated. Most of the upregulated proteins could be correlated with cardiomyocyte functionality. In contrast, the downregulated proteins were principally pluripotency markers, chaperones and ribosomal proteins. Higher expression levels of enzymes involved in DNA mismatch repair (MSH6) and in methylation reactions (MAT2A, AHCY) were also detected in the ESC, suggesting that these processes are more active in the ESC. In addition, the detection of gluthatione S-transferase alpha 4 (GSTA4) and Park7 DJ-1 protein (antioxidant) in ESC indicates that these cells have potential detoxification mechanisms. Furthermore, MBP affected the expression of 33 proteins, including MYH6, a cardiomyocyte-specific protein, which was significantly downregulated. MBP also affected the expression levels of chaperones, metabolic enzymes and chromatin modulating proteins, suggesting that MBP alters the differentiation process. Western blot analysis of MYH6 and HSPB1 confirmed the proteomic data. In addition, a favorable correlation was observed between protein expression and published changes in the expression of related genes at the transcriptomics level. Together, the results reveal potential protein markers that may be used as endpoints in an ESC based animal free alternative test for embryotoxicity though further studies are required for confirmation.


Cancer Research | 2007

Dominant-Negative but not Gain-of-Function Effects of a p53.R270H Mutation in Mouse Epithelium Tissue after DNA Damage

Susan W.P. Wijnhoven; Ewoud N. Speksnijder; Xiaoling Liu; Edwin Zwart; Conny Th. M. vanOostrom; Rudolf B. Beems; Esther M. Hoogervorst; Mirjam M. Schaap; Laura D. Attardi; Tyler Jacks; Harry van Steeg; Jos Jonkers; Annemieke de Vries

p53 alterations in human tumors often involve missense mutations that may confer dominant-negative or gain-of-function properties. Dominant-negative effects result in inactivation of wild-type p53 protein in heterozygous mutant cells and as such in a p53 null phenotype. Gain-of-function effects can directly promote tumor development or metastasis through antiapoptotic mechanisms or transcriptional activation of (onco)genes. Here, we show, using conditional mouse technology, that epithelium-specific heterozygous expression of mutant p53 (i.e., the p53.R270H mutation that is equivalent to the human hotspot R273H) results in an increased incidence of spontaneous and UVB-induced skin tumors. Expression of p53.R270H exerted dominant-negative effects on latency, multiplicity, and progression status of UVB-induced but not spontaneous tumors. Surprisingly, gain-of-function properties of p53.R270H were not detected in skin epithelium. Apparently, dominant-negative and gain-of-function effects of mutant p53 are highly tissue specific and become most manifest upon stabilization of p53 after DNA damage.


Toxicological Sciences | 2011

Evaluation of benzo(a)pyrene-induced gene mutations in male germ cells.

Nicole Verhofstad; Conny T. M. van Oostrom; Edwin Zwart; Lou M. Maas; Jan van Benthem; Frederik J. Van Schooten; Harry van Steeg; Roger W. L. Godschalk

Polycyclic aromatic hydrocarbons (PAHs) are mutagenic in somatic cells, whereas it remains unclear whether PAHs induce mutations in male germ cells, subsequently increasing health risks in offspring. Although results from the classical specific locus test are negative or inconclusive, recent studies with environmentally exposed animals suggest that PAHs are mutagenic in sperm cells. Therefore, we studied whether benzo(a)pyrene (B[a]P) was able to induce gene mutations in testis and sperm cells of wild-type (Wt) and Xpc(-/-) mice containing the pUR288 lacZ reporter gene. Mice were exposed to B[a]P (13 mg/kg body weight, three times per week) during 1, 4, or 6 weeks and sacrificed 6 weeks after the final exposure to obtain mutations in sperm derived from B[a]P-exposed spermatogonial stem cells. The lacZ gene mutation assay was used to assess mutant frequencies in spleen, testis, and mature sperm, and (32)P-postlabeling was used for the detection of DNA adducts in testis. Successful exposure was confirmed by a dose-related higher mutant frequency in spleen of Xpc(-/-) mice as compared with Wt mice. Mutant frequencies were also increased in all ethyl nitrosourea-exposed samples, which were used as positive control. Although B[a]P-related DNA adducts were detected in testis, mutant frequencies were not increased. On the other hand, B[a]P increased mutant frequencies in sperm of Wt mice, but not in Xpc(-/-) mice, after 6 weeks exposure. Therefore, we conclude that B[a]P can induce gene mutations in spermatogonial cells of mice, but it remains to be elucidated whether these mutations can be transmitted to offspring.


Molecular and Cellular Biology | 2008

The absence of Ser389 phosphorylation in p53 affects the basal gene expression level of many p53-dependent genes and alters the biphasic response to UV exposure in mouse embryonic fibroblasts

Wendy Bruins; Oskar Bruning; Martijs J. Jonker; Edwin Zwart; Tessa V. van der Hoeven; Jeroen L. A. Pennings; Han Rauwerda; Annemieke de Vries; Timo M. Breit

ABSTRACT Phosphorylation is important in p53-mediated DNA damage responses. After UV irradiation, p53 is phosphorylated specifically at murine residue Ser389. Phosphorylation mutant p53.S389A cells and mice show reduced apoptosis and compromised tumor suppression after UV irradiation. We investigated the underlying cellular processes by time-series analysis of UV-induced gene expression responses in wild-type, p53.S389A, and p53−/− mouse embryonic fibroblasts. The absence of p53.S389 phosphorylation already causes small endogenous gene expression changes for 2,253, mostly p53-dependent, genes. These genes showed basal gene expression levels intermediate to the wild type and p53−/−, possibly to readjust the p53 network. Overall, the p53.S389A mutation lifts p53-dependent gene repression to a level similar to that of p53−/− but has lesser effect on p53-dependently induced genes. In the wild type, the response of 6,058 genes to UV irradiation was strictly biphasic. The early stress response, from 0 to 3 h, results in the activation of processes to prevent the accumulation of DNA damage in cells, whereas the late response, from 12 to 24 h, relates more to reentering the cell cycle. Although the p53.S389A UV gene response was only subtly changed, many cellular processes were significantly affected. The early response was affected the most, and many cellular processes were phase-specifically lost, gained, or altered, e.g., induction of apoptosis, cell division, and DNA repair, respectively. Altogether, p53.S389 phosphorylation seems essential for many p53 target genes and p53-dependent processes.


Cancer Research | 2005

Lack of p53 Ser389 Phosphorylation Predisposes Mice to Develop 2-Acetylaminofluorene–Induced Bladder Tumors but not Ionizing Radiation–Induced Lymphomas

Esther M. Hoogervorst; Wendy Bruins; Edwin Zwart; Conny T. M. van Oostrom; Gerard van den Aardweg; Rudolf B. Beems; Jolanda van den Berg; Tyler Jacks; Harry van Steeg; Annemieke de Vries

Cellular activity of the tumor suppressor protein p53 is primarily regulated by posttranslational modifications. Phosphorylation of the COOH terminus, including Ser389, is thought to result in a conformational change of the p53 protein, enhancing DNA binding and transcriptional activity. In vitro studies presented here show that, in addition to UV radiation, Ser389 is phosphorylated upon exposure to 2-acetylaminofluorene (2-AAF). Both agents induce bulky DNA adducts repaired by nucleotide excision repair (NER). In contrast, ionizing radiation, known to induce DNA damage not repaired by NER, does not result in Ser389 phosphorylation. Previously, we have shown that p53.S389A mutant mice, lacking the Ser389 phosphorylation site, are sensitive to developing UV-induced skin tumors. Here, we show that p53.S389A mice are also prone to developing 2-AAF-induced urinary bladder tumors, whereas no increased tumor response was found upon ionizing irradiation. These results provide evidence for our hypothesis that phosphorylation of Ser389 is important for activation of p53 to exert its function as a tumor suppressor not exclusively upon the presence of UV-induced DNA damage, but also upon exposure to other bulky adduct-inducing agents. Analysis of 2-AAF- and UV-induced tumors from p53.S389A mice revealed the presence of additional p53 mutations, indicating that lack of Ser389 phosphorylation by itself is not sufficient to abrogate p53 function in tumor suppression. In addition, analyses of skin tumors of p53.S389A mice revealed an interesting hotspot mutation previously found exclusively in NER-deficient mice and patients.


DNA Repair | 2013

Slow accumulation of mutations in Xpc-/- mice upon induction of oxidative stress.

Joost P.M. Melis; Raoul V. Kuiper; Edwin Zwart; Joke Robinson; Jeroen L. A. Pennings; Conny T. M. van Oostrom; Mirjam Luijten; Harry van Steeg

XPC is one of the key DNA damage recognition proteins in the global genome repair route of the nucleotide excision repair (NER) pathway. Previously, we demonstrated that NER-deficient mouse models Xpa(-/-) and Xpc(-/-) exhibit a divergent spontaneous tumor spectrum and proposed that XPC might be functionally involved in the defense against oxidative DNA damage. Others have mechanistically dissected several functionalities of XPC to oxidative DNA damage sensitivity using in vitro studies. XPC has been linked to regulation of base excision repair (BER) activity, redox homeostasis and recruitment of ATM and ATR to damage sites, thereby possibly regulating cell cycle checkpoints and apoptosis. XPC has additionally been implicated in recognition of bulky (e.g. cyclopurines) and non-bulky DNA damage (8-oxodG). However, the ultimate contribution of the XPC functionality in vivo in the oxidative DNA damage response and subsequent mutagenesis process remains unclear. Our study indicates that Xpc(-/-) mice, in contrary to Xpa(-/-) and wild type mice, have an increased mutational load upon induction of oxidative stress and that mutations arise in a slowly accumulative fashion. The effect of non-functional XPC in vivo upon oxidative stress exposure appears to have implications in mutagenesis, which can contribute to the carcinogenesis process. The levels and rate of mutagenesis upon oxidative stress correlate with previous findings that lung tumors in Xpc(-/-) mice overall arise late in the lifespan and that the incidence of internal tumors in XP-C patients is relatively low in comparison to skin cancer incidence.


Archives of Toxicology | 2012

Dissecting modes of action of non-genotoxic carcinogens in primary mouse hepatocytes

Mirjam M. Schaap; Edwin Zwart; Paul F. K. Wackers; Ilse Huijskens; Bob van de Water; Timo M. Breit; Harry van Steeg; Martijs J. Jonker; Mirjam Luijten

Under REACH, the European Community Regulation on chemicals, the testing strategy for carcinogenicity is based on in vitro and in vivo genotoxicity assays. Given that non-genotoxic carcinogens are negative for genotoxicity and chronic bioassays are no longer regularly performed, this class of carcinogens will go undetected. Therefore, test systems detecting non-genotoxic carcinogens, or even better their modes of action, are required. Here, we investigated whether gene expression profiling in primary hepatocytes can be used to distinguish different modes of action of non-genotoxic carcinogens. For this, primary mouse hepatocytes were exposed to 16 non-genotoxic carcinogens with diverse modes of action. Upon profiling, pathway analysis was performed to obtain insight into the biological relevance of the observed changes in gene expression. Subsequently, both a supervised and an unsupervised comparison approach were applied to recognize the modes of action at the transcriptomic level. These analyses resulted in the detection of three of eight compound classes, that is, peroxisome proliferators, metalloids and skin tumor promotors. In conclusion, gene expression profiles in primary hepatocytes, at least in rodent hepatocytes, appear to be useful to detect some, certainly not all, modes of action of non-genotoxic carcinogens.

Collaboration


Dive into the Edwin Zwart's collaboration.

Top Co-Authors

Avatar

Harry van Steeg

Leiden University Medical Center

View shared research outputs
Top Co-Authors

Avatar

Mirjam M. Schaap

Leiden University Medical Center

View shared research outputs
Top Co-Authors

Avatar

Annemieke de Vries

Centre for Health Protection

View shared research outputs
Top Co-Authors

Avatar

Mirjam Luijten

Centre for Health Protection

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Tyler Jacks

Massachusetts Institute of Technology

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge