using-immunofluorescence-to-detect-pm25-induced-dna-damage-zebrafish

Using Immunofluorescence to Detect PM<sub>2.5</sub>-induced DNA Damage in Zebrafish Embryo Hearts

Ambient fine particulate matter (PM2.5) exposure can lead to cardiac developmental toxicity but the underlying molecular mechanisms are still unclear. ...

Soochow University

As the leading cause of death for gynecological cancers, ovarian cancer (OC) ranks fifth overall for cancer-related death among women. Emerging evidence has indicated that circular RNA (circRNA), recognized as functional non-coding transcripts in eukaryotic cells, may be involved in many physiological or pathological processes. It was reported that circ-ITCH is downregulated in multi cancers and serves as a powerful tumor suppressor among through a competing endogenous RNA (ceRNA) pathway. However, the existence and the role of circ-ITCH in OC was not reported. Here, we found a broad down-regulation of circ-ITCH in OC tissues and cells, which correlates with a worse prognosis in OC patients. Functional studies suggest that circ-ITCH overexpression inhibits the cell viability and motility by CCK8, cell cycle, wound healing assay and invasion assay. It also inhibits the tumorigenesis ability in xenograft NOD mice in vivo. Mechanically, we demonstrated that circ-TCH acts as a ceRNA to sponge miR-145, increases the level of RASA1, and inhibits the malignant progression of OC cells via the circ-ITCH-miR-145-RASA1 axis in vitro and in vivo. Taken together, our findings provide a novel tumor suppressive role regarding circ-ITCH function in the malignant progression of OC.

The circular RNA circ-ITCH suppresses ovarian carcinoma progression through targeting miR-145/RASA1 signaling.

Ovarian cancer (OC) is the leading cause of death from gynecological malignancy. Dual-specificity phosphatases (DUSPs) are proteins that are reported involved in carcinogenesis, but their roles in OC have not be extensively studied. Here, we found that DUSP5 is markedly down-regulated in OC tissues. We reanalyzed DUSP5 expression in OC using published microarray data from the Gene Expression Omnibus (GEO) database and found that patients with low DUSP5 expression have significantly shorter overall survival than those with high expression ( < 0.001). Down-regulation of DUSP5 in OC tissues was immunohistochemically confirmed in tissue microarrays containing 15 normal ovary tissue samples and 60 OC specimens. Functional studies suggest that DUSP5 silence facilitates cell proliferation, migration, and invasion of OC cells in vitro. DUSP5 over-expression inhibits cell proliferation but has no effect on OC cell migration or invasion. Mechanistically, silencing DUSP5 transcriptionally activates interleukin 33 (IL-33) expression and secretion. Blockage of IL-33 with a neutralizing anti-IL33 antibody attenuates the effect of DUSP5 silencing to promote cell proliferation, migration, and invasion. Moreover, recombinant IL-33 protein treatment dramatically promotes OC cell proliferation, migration, and invasion with DUSP5 over-expression. Our study provides proof of principle that DUSP5 down-regulation promotes proliferation, migration, and invasion of OC cells via activation of IL-33 signaling.

Dual-specificity phosphatase 5 suppresses ovarian cancer progression by inhibiting IL-33 signaling.

Recent studies have shown an association between maternal exposure to ambient fine particle matter (PM2.5) and congenital heart defects in the offspring, but the underlying molecular mechanisms are yet to be elucidated. Previously, we demonstrated that extractable organic matter (EOM) from PM2.5 induced heart defects in zebrafish embryos by activating the aromatic hydrocarbon receptor (AHR). Hence, we hypothesized that AHR mediates excessive reactive oxygen species (ROS) production, leading to the cardiac developmental toxicity of PM2.5. To test our hypothesis, we examined AHR activity and ROS levels in the heart of zebrafish embryos under a fluorescence microscope. mRNA expression levels were then quantified using qPCR whereas DNA damage and apoptosis were detected by immunofluorescence. Our results showed that the AHR inhibitor, CH223191 (CH) as well as the ROS scavenger, N-Acetyl-L-cysteine (NAC), significantly mitigated the PM2.5-induced cardiac malformations in zebrafish embryos. Furthermore, both CH and NAC diminished the EOM-elevated ROS generation, DNA damage and apoptosis in the test system. Incidentally, both CH and NAC attenuated the EOM-induced changes in the mRNA expression of genes involved in cardiac development (nkx2.5, sox9b), oxidative stress (nrf2a, nrf2b, gstp1, gstp2, sod2, ho1, cat) and apoptosis (p53, bax). We further confirmed that AHR activity is a necessary condition for EOM-induced ROS generation, DNA damage and apoptosis, through AHR knockdown. However, the ROS scavenger NAC did not counteract the EOM-induced AHR activity. In conclusion, our findings suggest that AHR mediates EOM-induced oxidative stress, resulting in DNA damage and apoptosis, thereby contributing to the cardiac developmental toxicity of PM2.5.

AHR-mediated ROS production contributes to the cardiac developmental toxicity of PM2.5 in zebrafish embryos.

Resveratrol (RSV), a natural polyphenolic compound commonly found in food, has antioxidant and aryl hydrocarbon receptor (AHR) antagonist effects. We have recently demonstrated that AHR mediated reactive oxygen species (ROS) generation contributes to the cardiac developmental toxicity of ambient fine particle matter (PM2.5). Thus, we hypothesized that RSV protects against the cardiac developmental toxicity of PM2.5 by inhibiting ROS generation and AHR activity. To test this concept, we exposed zebrafish embryos to extractable organic matter (EOM) from PM2.5 in the presence or absence of RSV. We found that RSV significantly counteracted EOM-induced cardiac malformations in zebrafish embryos. The EOM-induced ROS production, DNA damage and apoptosis in the heart of zebrafish embryos were also counteracted by RSV supplementation. Furthermore, RSV attenuated EOM-induced changes in the expression of genes involved in cardiac development (nkx2.5, sox9b, axin2), oxidative stress (nrf2a, nrf2b, gstp1, gstp2, sod1, sod2, cat) and apoptosis (p53, bax). However, RSV did not suppress EOM-induced AHR activity. In conclusion, our data indicates that RSV protects against the PM2.5-induced heart malformations by inhibiting oxidative stress rather than through AHR antagonism.

Resveratrol protects against PM2.5-induced heart defects in zebrafish embryos as an antioxidant rather than as an AHR antagonist.

Trichloroethylene (TCE), a widely used organic solvent, is a common environmental pollutant. Increasing evidence indicates that maternal TCE exposure is associated with congenital cardiac defects, but the underlining mechanisms remain largely unknown. In this study, we revealed that TCE exposure significantly induced heart defects and dysfunctions in zebrafish embryos. Heart tissues were dissected and subjected to high throughput sequencing and qPCR to identify differentially expressed miRNAs and mRNAs. The effects of miRNA were further verified by microinjection of antagomir or agomir. Reactive Oxygen Species (ROS) and cell proliferation were measured by using dichlorodihydrofluorescein diacetate (DCFH-DA) and EdU staining, respectively. Our results showed that 19 miRNAs were downregulated whereas 48 miRNAs were upregulated in the heart of zebrafish embryos. The downregulation of miR-133a and the upregulation of miR-182 were further validated. Moreover, we found that miR-133a agomir significantly alleviated the TCE-induced heart defects while miR-133a antagomir mimicked the toxic effect of TCE on heart development. Furthermore, miR-133a agomir significantly counteracted TCE-induced ROS production and excessive cell proliferation in the heart of zebrafish embryos. In conclusion, our results indicate that miR-133a mediates TCE-induced ROS generation, leading to excessive cell proliferation and heart defects.

Downregulation of miR-133a contributes to the cardiac developmental toxicity of trichloroethylene in zebrafish.

Trichloroethylene (TCE), a prevalent environmental contaminant, has been shown to induce cardiac malformations. Resveratrol (RSV) is a natural polyphenolic compound exhibiting protective effects on heart development. To investigate if RSV could protect against TCE-induced heart defects, we exposed zebrafish embryos to TCE (10 ppb) in the presence or absence of RSV (1 μg/mL). Our results showed that RSV significantly attenuated TCE-induced heart defects in zebrafish embryos. The TCE-induced ROS (reactive oxygen species) generation, 8-OHdG (8-hydroxy-2`-deoxyguanosine) formation and cell proliferation were significantly counteracted by RSV. Moreover, RSV attenuated the TCE-induced changes in mRNA expression or activity of genes involved in AHR and Nrf2 signal pathways. We further showed that RSV might inhibit TCE-enhanced cell proliferation by rescuing the downregulation of the p53/p21 axis. In conclusion, our data demonstrates that RSV protects against the cardiac developmental toxicity of TCE by inhibiting AHR activity, oxidative stress and cell proliferation.

Yujie Huang

School of Public Health

Soochow University

Using Immunofluorescence to Detect PM_2.5-induced DNA Damage in Zebrafish Embryo Hearts

Yujie Huang

School of Public Health

Soochow University

Using Immunofluorescence to Detect PM2.5-induced DNA Damage in Zebrafish Embryo Hearts

Using Immunofluorescence to Detect PM_2.5-induced DNA Damage in Zebrafish Embryo Hearts