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1.
Life (Basel) ; 13(12)2023 Dec 15.
Article En | MEDLINE | ID: mdl-38137946

Inflammation plays a pivotal role in the development and progression of inflammatory bowel disease (IBD), by contributing to tissue damage and exacerbating the immune response. The investigation of serotonin receptor 2A (5-HT2A) ligands and transient receptor potential (TRP) channel ligands is of significant interest due to their potential to modulate key inflammatory pathways, mitigate the pathological effects of inflammation, and offer new avenues for therapeutic interventions in IBD. This study investigates the anti-inflammatory effects of 5-HT2A ligands, including psilocybin, 4-AcO-DMT, and ketanserin, in combination with TRP channel ligands, including capsaicin, curcumin, and eugenol, on the inflammatory response induced by tumor necrosis factor (TNF)-α and interferon (IFN)-γ in human 3D EpiIntestinal tissue. Enzyme-linked immunosorbent assay was used to assess the expression of pro-inflammatory markers TNF-α, IFN-γ, IL-6, IL-8, MCP-1, and GM-CSF. Our results show that psilocybin, 4-AcO-DMT, and eugenol significantly reduce TNF-α and IFN-γ levels, while capsaicin and curcumin decrease these markers to a lesser extent. Psilocybin effectively lowers IL-6 and IL-8 levels, but curcumin, capsaicin, and 4-AcO-DMT have limited effects on these markers. In addition, psilocybin can significantly decrease MCP-1 and GM-CSF levels. While ketanserin lowers IL-6 and GM-CSF levels, there are no effects seen on TNF-α, IFN-γ, IL-8, or MCP-1. Although synergistic effects between 5-HT2A and TRP channel ligands are minimal in this study, the results provide further evidence of the anti-inflammatory effects of psilocybin and eugenol. Further research is needed to understand the mechanisms of action and the feasibility of using these compounds as anti-inflammatory therapies for conditions like IBD.

2.
Curr Issues Mol Biol ; 45(8): 6743-6774, 2023 Aug 15.
Article En | MEDLINE | ID: mdl-37623246

Intestinal inflammation and dysbiosis can lead to inflammatory bowel diseases (IBD) and systemic inflammation, affecting multiple organs. Developing novel anti-inflammatory therapeutics is crucial for preventing IBD progression. Serotonin receptor type 2A (5-HT2A) ligands, including psilocybin (Psi), 4-Acetoxy-N,N-dimethyltryptamine (4-AcO-DMT), and ketanserin (Ket), along with transient receptor potential (TRP) channel ligands like capsaicin (Cap), curcumin (Cur), and eugenol (Eug), show promise as anti-inflammatory agents. In this study, we investigated the cytotoxic and anti-inflammatory effects of Psi, 4-AcO-DMT, Ket, Cap, Cur, and Eug on human small intestinal epithelial cells (HSEIC). HSEIC were exposed to tumor necrosis factor (TNF)-α and interferon (IFN)-γ for 24 h to induce an inflammatory response, followed by treatment with each compound at varying doses (0-800 µM) for 24 to 96 h. The cytotoxicity was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and protein expression by Western blot (WB) analysis. As single treatments, Psi (40 µM), Cur (0.5 µM), and Eug (50 µM) significantly reduced COX-2 levels without cytotoxic effects. When combined, Psi (40 µM) and Cur (0.5 µM) exhibited synergy, resulting in a substantial decrease in COX-2 protein levels (-28× fold change), although the reduction in IL-6 was less pronounced (-1.6× fold change). Psi (20 µM) and Eug (25 µM) demonstrated the most favorable outcomes, with significant decreases in COX-2 (-19× fold change) and IL-6 (-10× fold change) protein levels. Moreover, the combination of Psi and Eug did not induce cytotoxic effects in vitro at any tested doses. This study is the first to explore the anti-inflammatory potential of psilocybin and 4-AcO-DMT in the intestines while highlighting the potential for synergy between the 5-HT2A and TRP channel ligands, specifically Psi and Eug, in alleviating the TNF-α/IFN-γ-induced inflammatory response in HSEIC. Further investigations should evaluate if the Psi and Eug combination has the therapeutic potential to treat IBD in vivo.

3.
Molecules ; 28(6)2023 Mar 14.
Article En | MEDLINE | ID: mdl-36985596

Inflammation is an organism's biological defense mechanism. Acute and chronic inflammation of the body triggers the production of pro- and anti-inflammatory pathways that can affect the content of cytokines in the brain and thus cause brain inflammation. Disorders such as depression and posttraumatic stress disorder (PTSD) are often associated with elevated inflammation. Recently, positive and promising clinical results of psilocybin for the treatment of depression and PTSD were reported. Thus, we decided to test whether psilocybin alone or in combination with eugenol, an anti-inflammatory and antioxidant agent, would prevent the increase in or decrease the content of cytokines in the brain of C57BL/6J mice injected with lipopolysaccharides (LPS). Two experiments were performed, one with pre-treatment of mice through gavage with psilocybin (0.88 mg/kg), eugenol (17.6 mg/kg), or combinations of psilocybin and eugenol (1:10, 1:20, or 1:50), followed by intraperitoneal injection of LPS, and the second, post-treatment, with initial injection with LPS, followed by treatment with psilocybin, eugenol, or their combination. Brain tissues were collected, and cytokines were analyzed by qRT-PCR, Western blot, and ELISA. Data were analyzed with a one-way ANOVA followed by Tukey's post hoc test or with multiple unpaired t-tests. LPS upregulated mRNA expression of COX-2, TNF-α, IL-1ß, and IL-6. All pre-treatments decreased the expression of COX-2 and TNF-α, with psilocybin alone and in 1:50 combination, with eugenol being the most effective. In the post-treatment, all combinations of psilocybin and eugenol were effective in reducing inflammation, with the 1:50 ratio displaying the most prominent results in reducing the mRNA content of tested cytokines. Western blot analysis confirmed the effect on COX-2 and IL-1ß proteins. Finally, the ELISA showed that post-treatment with psilocybin + eugenol (1:50) demonstrated the best results, decreasing the expression of multiple markers including IL-6 and IL-8. This demonstrates the anti-inflammatory effects of a combination of psilocybin and eugenol in the brain of animals with systemically induced inflammation.


Encephalitis , Tumor Necrosis Factor-alpha , Mice , Animals , Tumor Necrosis Factor-alpha/metabolism , Lipopolysaccharides/adverse effects , Eugenol/pharmacology , Eugenol/therapeutic use , Interleukin-6 , Psilocybin/pharmacology , Psilocybin/therapeutic use , Cyclooxygenase 2/genetics , Mice, Inbred C57BL , Cytokines/metabolism , Inflammation/chemically induced , Inflammation/drug therapy , Inflammation/metabolism , Anti-Inflammatory Agents/therapeutic use , RNA, Messenger
4.
PLoS One ; 10(8): e0133292, 2015.
Article En | MEDLINE | ID: mdl-26308334

Despite its cultivation as a source of food, fibre and medicine, and its global status as the most used illicit drug, the genus Cannabis has an inconclusive taxonomic organization and evolutionary history. Drug types of Cannabis (marijuana), which contain high amounts of the psychoactive cannabinoid Δ9-tetrahydrocannabinol (THC), are used for medical purposes and as a recreational drug. Hemp types are grown for the production of seed and fibre, and contain low amounts of THC. Two species or gene pools (C. sativa and C. indica) are widely used in describing the pedigree or appearance of cultivated Cannabis plants. Using 14,031 single-nucleotide polymorphisms (SNPs) genotyped in 81 marijuana and 43 hemp samples, we show that marijuana and hemp are significantly differentiated at a genome-wide level, demonstrating that the distinction between these populations is not limited to genes underlying THC production. We find a moderate correlation between the genetic structure of marijuana strains and their reported C. sativa and C. indica ancestry and show that marijuana strain names often do not reflect a meaningful genetic identity. We also provide evidence that hemp is genetically more similar to C. indica type marijuana than to C. sativa strains.


Cannabis/genetics , Genotyping Techniques , Cannabis/classification , Phylogeny , Polymorphism, Single Nucleotide , Species Specificity
5.
BMC Genomics ; 15: 681, 2014 Aug 13.
Article En | MEDLINE | ID: mdl-25128291

BACKGROUND: High density stress, also known as intraspecies competition, causes significant yield losses in a wide variety of crop plants. At the same time, increases in density tolerance through selective breeding and the concomitant ability to plant crops at a higher population density has been one of the most important factors in the development of high yielding modern cultivars. RESULTS: Physiological changes underlying high density stress were examined in Oryza sativa plants over the course of a life cycle by assessing differences in gene expression and metabolism. Moreover, the nitrogen limitation was examined in parallel with high density stress to gain a better understanding of physiological responses specific to high density stress. While both nitrogen limitation and high density resulted in decreased shoot fresh weight, tiller number, plant height and chlorophyll content, high density stress alone had a greater impact on physiological factors. Decreases in aspartate and glutamate concentration were found in plants grown under both stress conditions; however, high density stress had a more significant effect on the concentration of these amino acids. Global transcriptome analysis revealed a large proportion of genes with altered expression in response to both stresses. The presence of ethylene-associated genes in a majority of density responsive genes was investigated further. Expression of ethylene biosynthesis genes ACC synthase 1, ACC synthase 2 and ACC oxidase 7 were found to be upregulated in plants under high density stress. Plants at high density were also found to up regulate ethylene-associated genes and senescence genes, while cytokinin response and biosynthesis genes were down regulated, consistent with higher ethylene production. CONCLUSIONS: High density stress has similar but greater impact on plant growth and development compared to nitrogen limitation. Global transcriptome changes implicate ethylene as a volatile signal used to communicate proximity in under dense population growth condition and suggest a role for phytohormones in high density stress response in rice plants.


Ethylenes/metabolism , Gene Expression Profiling , Metabolomics , Nitrogen/metabolism , Oryza/genetics , Oryza/metabolism , Stress, Physiological , Aspartic Acid/metabolism , Genes, Plant/genetics , Glutamic Acid/metabolism , Oryza/growth & development , Oryza/physiology
6.
Plant Physiol ; 162(1): 132-44, 2013 May.
Article En | MEDLINE | ID: mdl-23548780

Chloroplast biogenesis has been well documented in higher plants, yet the complex methods used to regulate chloroplast activity under fluctuating environmental conditions are not well understood. In rice (Oryza sativa), the CYTOKININ-RESPONSIVE GATA TRANSCRIPTION FACTOR1 (Cga1) shows increased expression following light, nitrogen, and cytokinin treatments, while darkness and gibberellin reduce expression. Strong overexpression of Cga1 produces dark green, semidwarf plants with reduced tillering, whereas RNA interference knockdown results in reduced chlorophyll and increased tillering. Coexpression, microarray, and real-time expression analyses demonstrate a correlation between Cga1 expression and the expression of important nucleus-encoded, chloroplast-localized genes. Constitutive Cga1 overexpression increases both chloroplast biogenesis and starch production but also results in delayed senescence and reduced grain filling. Growing the transgenic lines under different nitrogen regimes indicates potential agricultural applications for Cga1, including manipulation of biomass, chlorophyll/chloroplast content, and harvest index. These results indicate a conserved mechanism by which Cga1 regulates chloroplast development in higher plants.


Chloroplasts/physiology , GATA Transcription Factors/genetics , Gene Expression Regulation, Plant , Oryza/genetics , Plant Growth Regulators/metabolism , Biomass , Chlorophyll/analysis , Chlorophyll/metabolism , Cytokinins/metabolism , Darkness , Flowers/cytology , Flowers/genetics , Flowers/growth & development , Flowers/physiology , GATA Transcription Factors/metabolism , Gene Expression , Gene Expression Profiling , Gibberellins/metabolism , Light , Nitrogen/metabolism , Oligonucleotide Array Sequence Analysis , Oryza/cytology , Oryza/growth & development , Oryza/physiology , Photosynthesis , Plant Leaves/genetics , Plant Leaves/growth & development , Plant Leaves/physiology , Plant Proteins/genetics , Plant Proteins/metabolism , Plants, Genetically Modified , RNA Interference , Seeds/cytology , Seeds/genetics , Seeds/growth & development , Seeds/physiology , Starch/analysis , Starch/metabolism
7.
PLoS One ; 6(11): e26765, 2011.
Article En | MEDLINE | ID: mdl-22102866

Chloroplast development is an important determinant of plant productivity and is controlled by environmental factors including amounts of light and nitrogen as well as internal phytohormones including cytokinins and gibberellins (GA). The paralog GATA transcription factors GNC and CGA1/GNL up-regulated by light, nitrogen and cytokinin while also being repressed by GA signaling. Modifying the expression of these genes has previously been shown to influence chlorophyll content in Arabidopsis while also altering aspects of germination, elongation growth and flowering time. In this work, we also use transgenic lines to demonstrate that GNC and CGA1 exhibit a partially redundant control over chlorophyll biosynthesis. We provide novel evidence that GNC and CGA1 influence both chloroplast number and leaf starch in proportion to their transcript level. GNC and CGA1 were found to modify the expression of chloroplast localized GLUTAMATE SYNTHASE (GLU1/Fd-GOGAT), which is the primary factor controlling nitrogen assimilation in green tissue. Altering GNC and CGA1 expression was also found to modulate the expression of important chlorophyll biosynthesis genes (GUN4, HEMA1, PORB, and PORC). As previously demonstrated, the CGA1 transgenic plants demonstrated significantly altered timing to a number of developmental events including germination, leaf production, flowering time and senescence. In contrast, the GNC transgenic lines we analyzed maintain relatively normal growth phenotypes outside of differences in chloroplast development. Despite some evidence for partial divergence, results indicate that regulation of both GNC and CGA1 by light, nitrogen, cytokinin, and GA acts to modulate nitrogen assimilation, chloroplast development and starch production. Understanding the mechanisms controlling these processes is important for agricultural biotechnology.


Amino Acid Oxidoreductases/metabolism , Arabidopsis Proteins/metabolism , Arabidopsis/metabolism , Chlorophyll/biosynthesis , GATA Transcription Factors/metabolism , Plant Leaves/metabolism , Amino Acid Oxidoreductases/genetics , Arabidopsis/genetics , Arabidopsis/growth & development , Arabidopsis Proteins/genetics , Chloroplasts/metabolism , Chromatin Immunoprecipitation , Cytokinins/pharmacology , GATA Transcription Factors/genetics , Gene Expression Regulation, Plant , Gibberellins/pharmacology , Nitrogen/metabolism , Plant Leaves/genetics , Plant Leaves/growth & development , Plants, Genetically Modified/genetics , Plants, Genetically Modified/growth & development , Plants, Genetically Modified/metabolism , RNA, Messenger/genetics , RNA, Plant/genetics , Real-Time Polymerase Chain Reaction , Starch/metabolism
8.
Aging (Albany NY) ; 3(6): 609-20, 2011 Jun.
Article En | MEDLINE | ID: mdl-21685513

Younger individuals are more prone to develop cancer upon ionizing radiation (IR) exposure. Radiation-induced tumors are associated with inefficient repair of IR-induced DNA damage and genome instability. Phosphorylation of histone H2AX (γ-H2AX) is the initial event in repair of IR-induced DNA damage on the chromatin flanking the DNA strand breaks. This step is crucially important for the repair of DNA strand breaks and for the maintenance of genome stability. We studied the molecular underpinnings of the age-related IR effects using an animal model. By assaying for IR-induced γ-H2AX foci we analyzed the induction and repair of the DNA strand breaks in spleen, thymus, liver, lung, kidney, cerebellum, hippocampus, frontal cortex and olfactory bulb of 7, 14, 24, 30 and 45 days old male and female mice as a function of age. We demonstrate that tissues of younger animals are much more susceptible to IR-induced DNA damage. Younger animals exhibited higher levels of γ-H2AX formation which partially correlated with cellular proliferation and expression of DNA repair proteins. Induction and persistence of γ-H2AX foci was the highest in lymphoid organs (thymus and spleen) of 7 and 14 day old mice. The lowest focal induction was seen in lung and brain of young animals. The mechanisms of cell and tissue-specificity of in vivo IR responses need to be further dissected. This study provides a roadmap for the future analyses of DNA damage and repair induction in young individuals.


Aging/physiology , DNA Damage , DNA/radiation effects , Age Factors , Animals , Brain/anatomy & histology , Brain/pathology , Brain/radiation effects , Cell Proliferation/radiation effects , Child , DNA Breaks, Double-Stranded , DNA Repair , Female , Histones/genetics , Histones/metabolism , Humans , Male , Mice , Phosphorylation , Radiation, Ionizing
9.
J Exp Bot ; 59(11): 2933-44, 2008.
Article En | MEDLINE | ID: mdl-18552353

Plants can survive a limiting nitrogen (N) supply by developing a set of N limitation adaptive responses. However, the Arabidopsis nla (nitrogen limitation adaptation) mutant fails to produce such responses, and cannot adapt to N limitation. In this study, the nla mutant was utilized to understand further the effect of NLA on Arabidopsis adaptation to N limitation. Grown with limiting N, the nla mutant could not accumulate anthocyanins and instead produced an N limitation-induced early senescence phenotype. In contrast, when supplied with limiting N and limiting phosphorus (Pi), the nla mutants accumulated abundant anthocyanins and did not show the N limitation-induced early senescence phenotype. These results support the hypothesis that Arabidopsis has a specific pathway to control N limitation-induced anthocyanin synthesis, and the nla mutation disrupts this pathway. However, the nla mutation does not affect the Pi limitation-induced anthocyanin synthesis pathway. Therefore, Pi limitation induced the nla mutant to accumulate anthocyanins under N limitation and allowed this mutant to adapt to N limitation. Under N limitation, the nla mutant had a significantly down-regulated expression of many genes functioning in anthocyanin synthesis, and an enhanced expression of genes involved in lignin production. Correspondingly, the nla mutant grown with limiting N showed a significantly lower production of anthocyanins (particularly cyanidins) and an increase in lignin contents compared with wild-type plants. These data suggest that NLA controls Arabidopsis adaptability to N limitation by channelling the phenylpropanoid metabolic flux to the induced anthocyanin synthesis, which is important for Arabidopsis to adapt to N limitation.


Anthocyanins/biosynthesis , Arabidopsis Proteins/metabolism , Arabidopsis/physiology , Nitrogen/metabolism , Phosphorus/metabolism , Ubiquitin-Protein Ligases/metabolism , Arabidopsis/genetics , Arabidopsis Proteins/genetics , Biosynthetic Pathways , Gene Expression Regulation , Lignin/biosynthesis , Mutation , Phenotype , Ubiquitin-Protein Ligases/genetics
10.
Int J Radiat Oncol Biol Phys ; 66(2): 327-30, 2006 Oct 01.
Article En | MEDLINE | ID: mdl-16965987

PURPOSE: Although modern cancer radiation therapy has led to increased patient survival rates, the risk of radiation treatment-related complications is becoming a growing problem. Among various complications, radiation also poses a threat to the progeny of exposed parents. It causes transgenerational genome instability that is linked to transgenerational carcinogenesis. Although the occurrence of transgenerational genome instability, which manifests as elevated delayed and nontargeted mutation, has been well documented, the mechanisms by which it arises remain obscure. We hypothesized that epigenetic alterations may play a pivotal role in the molecular etiology of transgenerational genome instability. METHODS AND MATERIALS: We studied the levels of cytosine DNA methylation in somatic tissues of unexposed offspring upon maternal, paternal, or combined parental exposure. RESULTS: We observed a significant loss of global cytosine DNA methylation in the thymus tissue of the offspring upon combined parental exposure. The loss of DNA methylation was paralleled by a significant decrease in the levels of maintenance (DNMT1) and de novo methyltransferases DNMT3a and 3b and methyl-CpG-binding protein MeCP2. Along with profound changes in DNA methylation, we noted a significant accumulation of DNA strand breaks in thymus, which is a radiation carcinogenesis target organ. CONCLUSIONS: The observed changes were indicative of a profound epigenetic dysregulation in the offspring, which in turn could lead to genome destabilization and possibly could serve as precursor for transgenerational carcinogenesis. Future studies are clearly needed to address the cellular and carcinogenic repercussions of those changes.


DNA Methylation/radiation effects , Epigenesis, Genetic/radiation effects , Genomic Instability/genetics , Maternal Exposure , Paternal Exposure , Animals , Cytosine/metabolism , DNA (Cytosine-5-)-Methyltransferase 1 , DNA (Cytosine-5-)-Methyltransferases/metabolism , DNA Damage , DNA Methyltransferase 3A , Female , Histones/metabolism , Liver/metabolism , Male , Mice , Mice, Inbred C57BL , Random Allocation , Spleen/metabolism , Thymus Gland/metabolism , Whole-Body Irradiation , DNA Methyltransferase 3B
11.
Plant Cell Physiol ; 47(6): 736-42, 2006 Jun.
Article En | MEDLINE | ID: mdl-16608867

Here we analyzed the influence of salt stress on plant genome stability. Homologous recombination events were detected in transgenic Arabidopsis plants that carried in their genome a beta-glucuronidase recombination marker. Recombination events were scored as blue sectors using a stereo microscope. Exposure to 50 mM salt resulted in a 3.0-fold increase in recombination frequency. To analyze the organ and tissue specificity of recombination events, we examined cross-sections of leaves, stems and roots. We found that nearly 30% of recombination events in plants grown under normal conditions and nearly 50% of events in plants grown on salt were undetected by the conventional method. Most of the recombination events represented a cluster/group of cells (12 on average), although events with single cells were also detected. Recombination events were very frequent in leaf mesophyll cells. On average, individual recombination events located on leaves contained more cells than events located on roots or stems. Analysis of recombination events in cross-sectioned tissue of salt-treated plants revealed a shift in the distribution of recombination events towards the vascular tissue. We discuss the significance of the finding for plant stress physiology.


Arabidopsis/drug effects , Arabidopsis/genetics , Recombination, Genetic/drug effects , Sodium Chloride/pharmacology , Arabidopsis/physiology , Chromosome Breakage/genetics , DNA, Plant/analysis , DNA, Plant/genetics , Gene Frequency , Genetic Markers/genetics , Genomic Instability/drug effects , Genomic Instability/genetics , Glucuronidase/analysis , Glucuronidase/genetics , Plant Leaves/chemistry , Plant Leaves/cytology , Plant Leaves/drug effects , Plant Leaves/genetics , Plant Roots/chemistry , Plant Roots/cytology , Plant Roots/drug effects , Plant Roots/genetics , Plant Stems/chemistry , Plant Stems/cytology , Plant Stems/drug effects , Plant Stems/genetics , Plants, Genetically Modified , Sequence Homology, Nucleic Acid
12.
Mutat Res ; 595(1-2): 145-55, 2006 Mar 20.
Article En | MEDLINE | ID: mdl-16442571

In this paper we analysed the genome stability of various Arabidopsis thaliana plant organs using a transgenic recombination system. The system was based on two copies of non-functional GUS (lines #651 and #11) or LUC (line #15D8) reporter genes serving as a recombination substrate. Both reporter assays showed that recombination in flowers or stems were rare events. Most of the recombination sectors were found in leaves and roots, with leaves having over 2-fold greater number of the recombination events per single cell genome as compared to roots. The recombination events per single genome were 9.7-fold more frequent on the lateral half of the leaves than on the medial halves. This correlated with a 2.5-fold higher metabolic activity in the energy source (lateral) versus energy sink (medial) of leaves. Higher metabolic activity was paralleled by a higher anthocyanin production in lateral halves. The level of double strand break (DSB) occurrence was also different among plant organs; the highest level was observed in roots and the lowest in leaves. High level of DSBs strongly positively correlated with the activity of the key repair enzymes, AtKU70 and AtRAD51. The ratio of AtRAD51 to AtKU70 expression was the highest in leaves, supporting the more active involvement of homologous recombination pathway in the repair of DSBs in this organ. Western blot analysis confirmed the real time PCR expression data for AtKU70 gene.


Plants/anatomy & histology , Plants/genetics , Recombination, Genetic/genetics , Sequence Homology , Anthocyanins/biosynthesis , Arabidopsis/anatomy & histology , Arabidopsis/genetics , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , DNA/metabolism , DNA Damage/genetics , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Gene Expression Profiling , Gene Expression Regulation, Plant , Genome, Plant/genetics , Hydrogen Peroxide/metabolism , Organ Specificity , Plant Leaves/enzymology , Plant Leaves/genetics , Plant Leaves/metabolism , Plants, Genetically Modified , Rad51 Recombinase/genetics , Rad51 Recombinase/metabolism , Ribulose-Bisphosphate Carboxylase/metabolism
13.
Carcinogenesis ; 27(3): 465-74, 2006 Mar.
Article En | MEDLINE | ID: mdl-16272168

Retinoblastoma (RB) tumor suppressor is a key regulator of apoptosis, a central mediator of the proliferative block induced by ionizing radiation (IR) and a binding target for a variety of proteins that regulate its activity. One of the recently discovered and the least investigated of these is the novel Rb-binding protein RBBP9/BOG. We studied the effects of acute and chronic low dose radiation (LDR) exposure on the induction of RBBP9 and RB signaling pathway in vivo in mouse spleen and found that RBBP9 played a pivotal role in IR responses in vivo. We observed that chronic LDR exposure led to a significant increase of RBBP9 expression in males and a significant decrease in females. Elevated RBBP9 expression in males was paralleled by a pronounced dephosphorylation of RB and a significant drop of PCNA and cyclin A expression. On the contrary, chronic exposure in females led to decreased levels of RBBP9 and increased levels of hyperphosphorylated RB (ppRB) in spleen. Decreased levels of ppRB in spleen of chronically exposed males were correlated with strongly elevated apoptotic rates. In females, the radiation-induced increase of apoptotic index was much less pronounced. Quite surprisingly, the observed sex-specific signaling changes did not result in the sex-specificity of cellular proliferation. The molecular mechanisms and possible repercussions of the radiation-induced sex differences in cellular proliferation and apoptosis are discussed.


Apoptosis/radiation effects , Cell Cycle Proteins/physiology , Intracellular Signaling Peptides and Proteins/physiology , Neoplasm Proteins/physiology , Radiation Injuries/physiopathology , Animals , Cell Proliferation , Dose-Response Relationship, Radiation , Female , Humans , Male , Mice , Mice, Inbred C57BL , Phosphorylation , Radiation Injuries/genetics , Radiation, Ionizing , Retinoblastoma Protein/metabolism , Serine Proteases , Sex Factors , Signal Transduction , Spleen/physiology
14.
Mol Cancer Res ; 3(10): 553-61, 2005 Oct.
Article En | MEDLINE | ID: mdl-16254189

Thymus, an important component of hematopoietic tissue, is a well-documented "target" of radiation carcinogenesis. Both acute and fractionated irradiation result in a high risk of leukemia and thymic lymphoma. However, the exact mechanisms underlying radiation-induced predisposition to leukemia and lymphoma are still unknown, and the contributions of genetic and epigenetic mechanisms in particular have yet to be defined. Global DNA hypomethylation is a well-known characteristic of cancer cells. Recent studies have also shown that tumor cells undergo prominent changes in histone methylation, particularly a substantial loss of trimethylation of histone H4-Lys20 and demethylation of genomic DNA. These losses are considered a universal marker of malignant transformation. In the present study, we investigated the effect of low-dose radiation exposure on the accumulation of DNA lesions and alterations of DNA methylation and histone H4-Lys20 trimethylation in the thymus tissue using an in vivo murine model. For the first time, we show that fractionated whole-body application of 0.5 Gy X-ray leads to decrease in histone H4-Lys20 trimethylation in the thymus. The loss of histone H4-Lys20 trimethylation was accompanied by a significant decrease in global DNA methylation as well as the accumulation of DNA damage as monitored by persistence of histone gammaH2AX foci in the thymus tissue of mice exposed to fractionated irradiation. Altered DNA methylation was associated with reduced expression of maintenance (DNMT1) and, to a lesser extent, de novo DNA methyltransferase DNMT3a in exposed animals. Expression of another de novo DNA methyltransferase DNMT3b was decreased only in males. Irradiation also resulted in approximately 20% reduction in the levels of methyl-binding proteins MeCP2 and MBD2. Our results show the involvement of epigenetic alterations in radiation-induced responses in vivo. These changes may play a role in genome destabilization that ultimately leads to cancer.


DNA Damage , DNA Methylation/radiation effects , DNA/radiation effects , Histones/metabolism , Histones/radiation effects , Thymus Gland/radiation effects , Animals , DNA (Cytosine-5-)-Methyltransferases/metabolism , Dose Fractionation, Radiation , Dose-Response Relationship, Radiation , Female , Gene Expression , Male , Methylation/radiation effects , Mice , Mice, Inbred C57BL , Thymus Gland/enzymology , Whole-Body Irradiation
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