Diethyl phthalate enhances expression of SIRT1 and DNMT3a during apoptosis in PC12 cells

Organism-derived phthalate derivatives as bioactive natural products

Phthalates are widely used in polymer materials as a plasticizer. These compounds possess potent toxic variations depending on their chemical structures. However, a growing body of evidence indicates that phthalate compounds are undoubtedly discovered in secondary metabolites of organisms, including plants, animals and microorganisms. This review firstly summarizes biological sources of various phthalates and their bioactivities reported during the past few decades as well as their environmental toxicities and public health risks. It suggests that these organisms are one of important sources of natural phthalates with diverse profiles of bioactivity and toxicity.

Glycolic Acid Silences Inflammasome Complex Genes, NLRC4 and ASC, by Inducing DNA Methylation in HaCaT Cells

AHAs (α-hydroxy acids), including glycolic acid (GA), have been widely used in cosmetic products and superficial chemical peels. Inflammasome complex has been shown to play critical roles in inflammatory pathways in human keratinocytes. However, the anti-inflammatory mechanism of GA is still unknown. The aim of this study is to investigate the relationship between the expression of the inflammasome complex and epigenetic modification to elucidate the molecular mechanism of the anti-inflammatory effect of GA in HaCaT cells. We evaluated NLRP3, NLRC4, AIM2, and ASC inflammasome complex gene expression on real-time polymerase chain reaction (PCR). Methylation changes were detected in these genes following treatment with DNA methyltransferase (DNMT) inhibitor 5-aza-2'-deoxycytidine (5-Aza) with or without the addition of GA using methylation-specific PCR (MSP). GA inhibited the expressions of these inflammasome complex genes, and the decreases in the expressions of mRNA were reversed by 5-Aza treatment. Methylation was detected in NLRC4 and ASC on MSP, but not in NLRP3 or AIM2. GA decreased NLRC4 and ASC gene expression by increasing not only DNA methyltransferase 3B (DNMT-3B) protein level, but also total DNMT activity. Furthermore, silencing of DNMT-3B (shDNMT-3B) increased the expressions of NLRC4 and ASC. Our data demonstrated that GA treatment induces hypermethylation of promoters of NLRC4 and ASC genes, which may subsequently lead to the hindering of the assembly of the inflammasome complex in HaCaT cells. These results highlight the anti-inflammatory potential of GA-containing cosmetic agents in human skin cells and demonstrate for the first time the role of aberrant hypermethylation in this process.

Developmental profiles and expression of the DNA methyltransferase genes in the fathead minnow (Pimephales promelas) following exposure to di-2-ethylhexyl phthalate

DNA methylation is an epigenetic regulator of gene expression, and this process has been shown to be disrupted by environmental contaminants. Di-2-(ethylhexyl) phthalate (DEHP) and related phthalate esters have been shown to affect development in early life stages of fish and can alter genomic methylation patterns in vertebrates. The objectives of this study were the following: (1) Describe the expression patterns of the DNA methyltransferase (dnmt) genes during early fathead minnow (FHM) development. These genes are critical for methylation and imprinting during development. (2) Determine the effects of DEHP on the development of FHM larvae [1 and 14 days post-hatch (dph)]. (3) Determine the effect of DEHP on dnmt expression and global methylation status in larval FHM. FHMs were first collected over a developmental time course [1, 3, 5, 6, and 14 days post-fertilization (dpf)] to investigate the expression patterns of five dnmt isoforms. The expression of dnmt1 and dnmt7 was relatively high in embryos at 1 dpf but was variable in expression, and these transcripts were later expressed at a lower level (>3 dpf); dnmt3 was significantly higher in embryos at 1 dpf compared to those at 3 dpf. Dnmt6 showed more of a constitutive pattern of expression during the first 2 weeks of development, and the mRNA levels of dnmt8 were higher in embryos at 5 and 6 dpf compared to those at 1 and 3 dpf, corresponding to the hatching period of the embryos. A waterborne exposure to three concentrations of DEHP (1, 10 and 100 µg/L) was conducted on 1-day FHM embryos for 24 h and on larval fish for 2 weeks, ending at 14 dpf. DEHP did not negatively affect survival, hatch rate, or the expression of dnmt isoforms in FHMs. There were no differences in global cytosine methylation following DEHP treatments in 14 dpf larvae, suggesting that environmentally relevant levels of DEHP may not affect global methylation at this stage of FHM development. However, additional targeted methylome studies are required to determine whether specific gene promoters are differently methylated following exposure to DEHP. This study offers new insight into the roles of the dnmt enzymes during FHM development.

Screening of phthalate esters in 47 branded perfumes

In the last few years, the use of phthalates in perfumes has gained attention because these chemicals are sometimes added intentionally as a solvent and a fixative. Five phthalate esters, dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), benzyl butyl phthalate (BBP), and diethyl hexyl phthalate (DEHP), were measured in 47 branded perfumes using headspace solid phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS). The results revealed considerable amounts of phthalate in all 47 brands with detection frequencies > limit of quantitation in the following order: DEP (47/47) > DMP (47/47) > BBP (47/47) > DEHP (46/47) > DBP (23/45). Of the 47 brands, 68.1, 72.3, 85.1, 36.2, and 6.7 % had DEP, DMP, BBP, DEHP, and DBP levels, respectively, above their reported threshold limits. Of these phthalates, DEP was found to have the highest mean value (1621.625 ppm) and a maximum of 23,649.247 ppm. The use of DEP in the perfume industry is not restricted because it does not pose any known health risks for humans. DMP had the second highest level detected in the perfumes, with a mean value of 30.202 ppm and a maximum of 405.235 ppm. Although DMP may have some uses in cosmetics, it is not as commonly used as DEP, and again, there are no restrictions on its use. The levels of BBP were also high, with a mean value of 8.446 ppm and a maximum of 186.770 ppm. Although the EU banned the use of BBP in cosmetics, 27 of the tested perfumes had BBP levels above the threshold limit of 0.1 ppm. The mean value of DEHP found in this study was 5.962 ppm, and a maximum was 147.536 ppm. In spite of its prohibition by the EU, 7/28 perfumes manufactured in European countries had DEHP levels above the threshold limit of 1 ppm. The DBP levels were generally low, with a mean value of 0.0305 ppm and a maximum value of 0.594 ppm. The EU banned the use of DBP in cosmetics; however, we found three brands that were above the threshold limit of 0.1 ppm, and all were manufactured in European countries. The results of this study are alarming and definitely need to be brought to the attention of the public and health regulators. Although some phthalate compounds are still used in cosmetics, many scientists and environmental activists have argued that phthalates are endocrine-disrupting chemicals that have not been yet proven to be safe for any use, including cosmetics. Phthalates may also have different degrees of estrogenic modes of action. Furthermore, we should not dismiss the widespread use of phthalates in everyday products and exposure to these chemicals from sources such as food, medications, and other personal care products.

Changes in the expression of epigenetic factors during copper-induced apoptosis in PC12 cells

Despite extensive research on copper toxicity the mechanisms involved are not fully characterized. There have been many recent reports concerning the relationship between epigenetic factors and cell metabolism, but the effects of copper exposure on epigenetic factors have not been investigated. In this study, an in vitro culture system was employed to study the influence of copper on apoptosis and epigenetic factors in PC12 cells. When PC12 cells were exposed to copper, DNA damage was observed as DNA fragmentation. In addition, cytosolic cytochrome c levels were increased by copper treatment. These results suggested that copper induced apoptosis via an oxidative stress pathway. This was consistent with the observation that copper-induced apoptosis was enhanced by further oxidative stress induced by exposing cells to H₂O₂. In addition, the epigenetic factors were significantly increased in apoptotic cells following exposure to copper and oxidative stress.

Green tea extract increases mRNA expression of enzymes which influence epigenetic marks in newborn female offspring from undernourished pregnant mother

Biochemical and toxicological properties of catechin remain unclear, e.g.; how catechin affects female offspring from undernourished pregnant dams. Here, to elucidate effects of low prenatal protein on female offspring health status, changes of enzymes which modify epigenetic marks related with metabolism in kidneys from newborns were investigated after continuously administering catechin extracted from green tea to lactating maternal rats after pregnant undernourishment. We found that green tea extract intake during lactation up-regulated the activation of AMP-activated protein kinase in young female offspring from protein-restricted dams and modulated the AMP-activated protein kinase pathway in the kidney. This pathway was indicated to be stimulated by SIRT1 gene expression. The feeding of green tea extract to protein-restricted dams during lactation is likely to up-regulate AMP-activated protein kinase activation and may partly lead to alterations of the AMP-activated protein kinase pathway in female offspring kidneys. In addition, energy metabolism in fetal and offspring period with green tea extract administration might be related to enzymes which modify epigenetic marks such as DNA methyltransferase 1 and 3a.