Up-regulation of Siah1 by ethanol triggers apoptosis in neural crest cells through p38 MAPK-mediated activation of p53 signaling pathway

Nano-TiO2 regulates the MAPK (ERK, P38) pathway to promote apoptosis and inhibit proliferation of human colon cells

BACKGROUND

Nano titanium dioxides (TiO2) are widely used in drug development, food additives and packaging materials. Although several studies have demonstrated the poisonousness of TiO2 in vivo and in vitro, the underlying molecular mechanisms have not been fully revealed.

METHODS

Characterization of TiO2 by FTIR, XRD, TEM and DLS. The NCM460 cell line, representing normal colon epithelial cells, was utilized as a model to assess the impact of TiO2 nanoparticles (TiO2-NPs) on cell proliferation and apoptosis. The potential molecular mechanisms underlying its toxic effects were investigated through transcriptome analysis, RT-qPCR, and western blot experiments.

RESULTS

The particle size of the TiO2-NPs used is about 25 nm, which has typical characteristics of anatase. TiO2-NPs at a concentration of 30-60 μg/mL will cause changes in colon cell morphology, decreased proliferation ability, and increased number of apoptotic cells. TiO2-NPs at a concentration of 6 μg/mL did not significantly modify the transcriptome expression profile of colon cells; while 30 μg/mL had a significant effect, leading to up-regulation of gene expression. The differentially expressed genes predominantly modulate the MAPK signaling pathway, TNF signaling pathway, cytokine-cytokine receptor interaction, and other related pathways. Further, western blot analysis revealed that higher concentrations of TiO2-NPs (30-60 μg/mL) could up-regulate the expression of P53, P21 and Bax, while down-regulating the expression of Bcl2 by regulating the MAPK (ERK, P38) signaling pathway. Simultaneously, it also promoted the decreased in Fos protein expression and inhibited the phosphorylation of Jun and Fos.

CONCLUSION

This study demonstrates that TiO2-NPs may exert potential toxic effects on colon cells, and therefore the intake of TiO2-NPs should be strictly regulated in practical applications.

Alcohol exposure suppresses ribosome biogenesis and causes nucleolar stress in cranial neural crest cells

Prenatal alcohol exposure (PAE) causes cognitive impairment and a distinctive craniofacial dysmorphology, due in part to apoptotic losses of the pluripotent cranial neural crest cells (CNCs) that form facial bones and cartilage. We previously reported that PAE rapidly represses expression of >70 ribosomal proteins (padj = 10-E47). Ribosome dysbiogenesis causes nucleolar stress and activates p53-MDM2-mediated apoptosis. Using primary avian CNCs and the murine CNC line O9-1, we tested whether nucleolar stress and p53-MDM2 signaling mediates this apoptosis. We further tested whether haploinsufficiency in genes that govern ribosome biogenesis, using a blocking morpholino approach, synergizes with alcohol to worsen craniofacial outcomes in a zebrafish model. In both avian and murine CNCs, pharmacologically relevant alcohol exposure (20mM, 2hr) causes the dissolution of nucleolar structures and the loss of rRNA synthesis; this nucleolar stress persisted for 18-24hr. This was followed by reduced proliferation, stabilization of nuclear p53, and apoptosis that was prevented by overexpression of MDM2 or dominant-negative p53. In zebrafish embryos, low-dose alcohol or morpholinos directed against ribosomal proteins Rpl5a, Rpl11, and Rps3a, the Tcof homolog Nolc1, or mdm2 separately caused modest craniofacial malformations, whereas these blocking morpholinos synergized with low-dose alcohol to reduce and even eliminate facial elements. Similar results were obtained using a small molecule inhibitor of RNA Polymerase 1, CX5461, whereas p53-blocking morpholinos normalized craniofacial outcomes under high-dose alcohol. Transcriptome analysis affirmed that alcohol suppressed the expression of >150 genes essential for ribosome biogenesis. We conclude that alcohol causes the apoptosis of CNCs, at least in part, by suppressing ribosome biogenesis and invoking a nucleolar stress that initiates their p53-MDM2 mediated apoptosis. We further note that the facial deficits that typify PAE and some ribosomopathies share features including reduced philtrum, upper lip, and epicanthal distance, suggesting the facial deficits of PAE represent, in part, a ribosomopathy.

SIAH1 facilitates the migration and invasion of gastric cancer cells through promoting the ubiquitination and degradation of RECK

Siah E3 ubiquitin protein ligase 1 (SIAH1) has been reported to participate in the development of several human cancers, including gastric cancer. However, the effect and mechanism of SIAH1 on the migration and invasion of gastric cancer cells need be further explored. Here, we first analyzed the clinical value of SIAH1 in gastric cancer, and found that SIAH1 was up-regulated in gastric cancer and associated with a poor prognosis. In addition, silencing of SIAH1 significantly inhibited the migration and invasion of gastric cancer cells through inhibiting the expression of matrix metalloproteinase-9 (MMP9), while overexpression of SIAH1 had the opposite effect. Molecularly, we provided the evidence that reversion-inducing cysteine-rich protein with Kazal motifs (RECK) was a potential substrate of SIAH1. We determined that SIAH1 could destabilize RECK through promoting its ubiquitination and degradation via proteasome pathway. We also found RECK was involved in SIAH1-regulated gastric cancer cell migration and invasion. In conclusion, SIAH1 is up-regulated in gastric cancer, which promotes the migration and invasion of gastric cancer cells through regulating RECK-MMP9 pathway.

Alcohol Exposure Induces Nucleolar Stress and Apoptosis in Mouse Neural Stem Cells and Late-Term Fetal Brain

Prenatal alcohol exposure (PAE) is a leading cause of neurodevelopmental disability through its induction of neuronal growth dysfunction through incompletely understood mechanisms. Ribosome biogenesis regulates cell cycle progression through p53 and the nucleolar cell stress response. Whether those processes are targeted by alcohol is unknown. Pregnant C57BL/6J mice received 3 g alcohol/kg daily at E8.5-E17.5. Transcriptome sequencing was performed on the E17.5 fetal cortex. Additionally, primary neural stem cells (NSCs) were isolated from the E14.5 cerebral cortex and exposed to alcohol to evaluate nucleolar stress and p53/MDM2 signaling. Alcohol suppressed KEGG pathways involving ribosome biogenesis (rRNA synthesis/processing and ribosomal proteins) and genes that are mechanistic in ribosomopathies (Polr1d, Rpl11; Rpl35; Nhp2); this was accompanied by nucleolar dissolution and p53 stabilization. In primary NSCs, alcohol reduced rRNA synthesis, caused nucleolar loss, suppressed proliferation, stabilized nuclear p53, and caused apoptosis that was prevented by dominant-negative p53 and MDM2 overexpression. Alcohol's actions were dose-dependent and rapid, and rRNA synthesis was suppressed between 30 and 60 min following alcohol exposure. The alcohol-mediated deficits in ribosomal protein expression were correlated with fetal brain weight reductions. This is the first report describing that pharmacologically relevant alcohol levels suppress ribosome biogenesis, induce nucleolar stress in neuronal populations, and involve the ribosomal/MDM2/p53 pathway to cause growth arrest and apoptosis. This represents a novel mechanism of alcohol-mediated neuronal damage.

Exploring the roles of noncoding RNAs in craniofacial abnormalities: A systematic review

Congenital craniofacial abnormalities are congenital anomalies of variable expressivity and severity with a recognizable set of abnormalities, which are derived from five identifiable primordial structures. They can occur unilaterally or bilaterally and include various malformations such as cleft lip with/without palate, craniosynostosis, and craniofacial microsomia. To date, the molecular etiology of craniofacial abnormalities is largely unknown. Noncoding RNAs (ncRNAs), including microRNAs, long ncRNAs, circular RNAs and PIWI-interacting RNAs, function as major regulators of cellular epigenetic hallmarks via regulation of various molecular and cellular processes. Recently, aberrant expression of ncRNAs has been implicated in many diseases, including craniofacial abnormalities. Consequently, this review focuses on the role and mechanism of ncRNAs in regulating craniofacial development in the hope of providing clues to identify potential therapeutic targets.

Exosome-shuttled miR-126 mediates ethanol-induced disruption of neural crest cell-placode cell interaction by targeting SDF1

During embryonic development, 2 populations of multipotent stem cells, cranial neural crest cells (NCCs) and epibranchial placode cells (PCs), are anatomically adjacent to each other. The coordinated migration of NCCs and PCs plays a major role in the morphogenesis of craniofacial skeletons and cranial nerves. It is known that ethanol-induced dysfunction of NCCs and PCs is a key contributor to the defects of craniofacial skeletons and cranial nerves implicated in fetal alcohol spectrum disorder (FASD). However, how ethanol disrupts the coordinated interaction between NCCs and PCs was not elucidated. To fill in this gap, we established a well-designed cell coculture system to investigate the reciprocal interaction between human NCCs (hNCCs) and human PCs (hPCs), and also monitored the migration behavior of NCCs and PCs in zebrafish embryos. We found that ethanol exposure resulted in a disruption of coordinated hNCCs-hPCs interaction, as well as in zebrafish embryos. Treating hNCCs-hPCs with exosomes derived from ethanol-exposed hNCCs (ExoEtOH) mimicked ethanol-induced impairment of hNCCs-hPCs interaction. We also observed that SDF1, a chemoattractant, was downregulated in ethanol-treated hPCs and zebrafish embryos. Meanwhile, miR-126 level in ExoEtOH was significantly higher than that in control exosomes (ExoCon). We further validated that ExoEtOH-encapsulated miR-126 from hNCCs can be transferred to hPCs to suppress SDF1 expression in hPCs. Knockdown of SDF1 replicated ethanol-induced abnormalities either in vitro or in zebrafish embryos. On the contrary, overexpression of SDF1 or inhibiting miR-126 strongly rescued ethanol-induced impairment of hNCCs-hPCs interaction and developmental defects.

Neural crest cells and fetal alcohol spectrum disorders: Mechanisms and potential targets for prevention

Fetal alcohol spectrum disorders (FASD) are a group of preventable and nongenetic birth defects caused by prenatal alcohol exposure that can result in a range of cognitive, behavioral, emotional, and functioning deficits, as well as craniofacial dysmorphology and other congenital defects. During embryonic development, neural crest cells (NCCs) play a critical role in giving rise to many cell types in the developing embryos, including those in the peripheral nervous system and craniofacial structures. Ethanol exposure during this critical period can have detrimental effects on NCC induction, migration, differentiation, and survival, leading to a broad range of structural and functional abnormalities observed in individuals with FASD. This review article provides an overview of the current knowledge on the detrimental effects of ethanol on NCC induction, migration, differentiation, and survival. The article also examines the molecular mechanisms involved in ethanol-induced NCC dysfunction, such as oxidative stress, altered gene expression, apoptosis, epigenetic modifications, and other signaling pathways. Furthermore, the review highlights potential therapeutic strategies for preventing or mitigating the detrimental effects of ethanol on NCCs and reducing the risk of FASD. Overall, this article offers a comprehensive overview of the current understanding of the impact of ethanol on NCCs and its role in FASD, shedding light on potential avenues for future research and intervention.

Bioinformatics Analysis of Hub Genes Involved in Alcohol-Related Hemifacial Microsomia Pathogenesis

OBJECTIVE

Alcohol is a recognized teratogen, and alcohol exposure increases the risk for hemifacial microsomia (HFM) of the fetus during maternal pregnancy. The present study aimed to explore potential mechanisms and verify hub genes of HFM associated with alcohol by bioinformatics methods.

METHODS

First, HFM and alcohol pathogenic genes were obtained. Thereafter, a protein-protein interactional (PPI) network was constructed. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses and molecular complex detection were performed by Metascape. Finally, we used the cytoHubba plugin to screen the hub genes.

RESULTS

A total of 43 HFM genes and 50 optimal alcohol candidate genes were selected. The PPI networks for pathogenic genes contained 93 nodes and 503 edges. Functional enrichment analysis largely focused on tissue formation and development. Two modules were identified from the PPI network, and 10 hub genes were screened out. The genes most relevant to alcohol-induced HFM pathogenesis included CTNNB1, TP53, MYC, HDAC1, and SOX2.

CONCLUSIONS

This study identified some significant hub genes, pathways, and modules of HFM related to alcohol by bioinformatics analyses. Our results suggest that the CTNNB1, TP53, MYC, HDAC1, and SOX B1 gene subfamilies may have played a major role in alcohol-induced HFM.

Up-regulation of microRNA-34a mediates ethanol-induced impairment of neural crest cell migration in vitro and in zebrafish embryos through modulating epithelial-mesenchymal transition by targeting Snail1

Prenatal ethanol exposure can impair neural crest cell (NCC) development, including NCC survival, differentiation and migration, contributing to the craniofacial dysmorphology in Fetal Alcohol Spectrum Disorders (FASD). Epithelial-mesenchymal transition (EMT) plays an important role in regulating the migration of NCCs. The objective of this study is to determine whether ethanol exposure can suppress NCC migration through inhibiting EMT and whether microRNA-34a (miR-34a) is involved in the ethanol-induced impairment of EMT in NCCs. We found that exposure to 100 mM ethanol significantly inhibited the migration of NCCs. qRT-PCR and Western Blot analysis revealed that exposure to ethanol robustly reduced the mRNA and protein expression of Snail1, a critical transcriptional factor that has a pivotal role in the regulation of EMT. Ethanol exposure also significantly increased the mRNA expression of the Snail1 target gene E-cadherin1 and inhibited EMT in NCCs. We also found that exposure to ethanol significantly elevated the expression of miR-34a that targets Snail1 in NCCs. In addition, down-regulation of miR-34a prevented ethanol-induced repression of Snail1 and diminished ethanol-induced upregulation of Snail1 target gene E-cadherin1 in NCCs. Inhibition of miR-34a restored EMT and prevented ethanol-induced inhibition of NCC migration in vitro and in zebrafish embryos in vivo. These results demonstrate that ethanol-induced upregulation of miR-34a contributes to the impairment of NCC migration through suppressing EMT by targeting Snail1.

Loss of tumor protein 53 protects against alcohol-induced facial malformations in mice and zebrafish

BACKGROUND

Alcohol exposure during the gastrulation stage of development causes the craniofacial and brain malformations that define fetal alcohol syndrome. These malformations, such as a deficient philtrum, are exemplified by a loss of midline tissue and correspond, at least in part, to regionally selective cell death in the embryo. The tumor suppressor protein Tp53 is an important mechanism for cell death, but the role of Tp53 in the consequences of alcohol exposure during the gastrulation stage has yet to be examined. The current studies used mice and zebrafish to test whether genetic loss of Tp53 is a conserved mechanism to protect against the effects of early developmental stage alcohol exposure.

METHODS

Female mice, heterozygous for a mutation in the Tp53 gene, were mated with Tp53 heterozygous males, and the resulting embryos were exposed during gastrulation on gestational day 7 (GD 7) to alcohol (two maternal injections of 2.9 g/kg, i.p., 4 h apart) or a vehicle control. Zebrafish mutants or heterozygotes for the tp53^zdf1  M214K mutation and their wild-type controls were exposed to alcohol (1.5% or 2%) beginning 6 h postfertilization (hpf), the onset of gastrulation.

RESULTS

Examination of GD 17 mice revealed that eye defects were the most common phenotype among alcohol-exposed fetuses, occurring in nearly 75% of the alcohol-exposed wild-type fetuses. Tp53 gene deletion reduced the incidence of eye defects in both the heterozygous and mutant fetuses (to about 35% and 20% of fetuses, respectively) and completely protected against alcohol-induced facial malformations. Zebrafish (4 days postfertilization) also demonstrated alcohol-induced reductions of eye size and trabeculae length that were less common and less severe in tp53 mutants, indicating a protective effect of tp53 deletion.

CONCLUSIONS

These results identify an evolutionarily conserved role of Tp53 as a pathogenic mechanism for alcohol-induced teratogenesis.

Tanshinone IIA alleviates acute ethanol-induced myocardial apoptosis mainly through inhibiting the expression of PDCD4 and activating the PI3K/Akt pathway

Myocardial apoptosis contributes to acute ethanol-induced cardiac injury. Improving immoderate apoptosis has become the potential therapeutic strategy for acute ethanol-induced heart damage. Previous studies reported that Tanshinone IIA (Tan IIA), a key ingredient extracted from Salvia miltiorrhiza Bunge, performed an anti-apoptotic role against acute ethanol-related cell damage. In this study, we investigated whether Tan IIA protected the acute ethanol-induced cardiac damage in vivo and in vitro. C57BL/6 mice were treated with acute ethanol and then treated with Tan IIA. The results showed that Tan IIA significantly improved heart function and blocked myocardial apoptosis. Acute ethanol exposure induced H9C2 cells apoptosis. Treatment with Tan IIA abrogated acute ethanol-induced H9C2 cells apoptosis. Mechanistically, Tan IIA inhibited apoptosis by downregulating the programmed cell death protein 4 (PDCD4) expression and activating the phosphoinositide 3-kinase (PI3K)/Akt pathway. Furthermore, PDCD4 overexpression abrogated Tan IIA-mediated anti-apoptotic role and activation on the PI3K/Akt pathway. Interestingly, the PI3K inhibitor (LY294002) application significantly attenuated the main protective effects of Tan IIA. In conclusion, Tan IIA improves acute ethanol-induced myocardial apoptosis mainly through regulating the PDCD4 expression and activating the PI3K/Akt signaling pathway. We provide evidence that Tan IIA is a new treatment approach for acute ethanol-induced heart damage.

Bioinformatics analysis of candidate genes involved in ethanol-induced microtia pathogenesis based on a human genome database: GeneCards

OBJECTIVE

Ethanol used by women during pregnancy increases the risk for microtia in the foetus. Traditionally, laboratory experiments and Mouse Genome Informatics (MGI) have been used to explore microtia pathogenesis. The aim of this study was to screen and verify hub genes involved in ethanol-induced microtia and to explore the potential molecular mechanisms.

METHODS

Overlapping genes related to ethanol and microtia were acquired from the GeneCards database and filtered by confidence score. These genes were further analysed via bioinformatics. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis results were visualized with the clusterProfiler R package. A protein-protein interaction (PPI) network was constructed based on data from the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database.

RESULTS

Overall, 41 genes related to both ethanol and microtia were identified. The genes most relevant to ethanol-induced microtia pathogenesis included FGFR-2, FGFR-3, FGF-8, TP53, IGF1, SHH, CTNNB1, and PAX6, among others. Most genes were strongly enriched for tissue and organ development in GO analysis. Additionally, many genes were enriched in the Ras, FoxO, MAPK, and PI3K-Akt signalling pathways in KEGG analysis.

CONCLUSIONS

Bioinformatics analysis was conducted on genes currently known to be related to ethanol-induced microtia pathogenesis. We propose that mechanisms involving FGF-family genes, TP53, IGF1 and SHH contribute significantly to ethanol-induced microtia and the accompanying malformation of other structures.

Treatment and Prevention of Neurocristopathies

Neurocristopathies form a heterogeneous group of rare diseases caused by abnormal development of neural crest cells. Heterogeneity of neurocristopathies directly relates to the nature of these migratory and multipotent cells, which generate dozens of specialized cell types throughout the body. Neurocristopathies are thus characterized by congenital malformations of tissues/organs that otherwise appear to have very little in common, such as the craniofacial skeleton and enteric nervous system. Treatment options are currently very limited, mainly consisting of corrective surgeries. Yet, as reviewed here, analyses of normal and pathological neural crest development in model organisms have opened up the possibility for better treatment options involving cellular and molecular approaches. These approaches provide hope that some neurocristopathies might soon be curable or preventable.

Sulforaphane Protects Against Ethanol-Induced Apoptosis in Human Neural Crest Cells Through Diminishing Ethanol-Induced Hypermethylation at the Promoters of the Genes Encoding the Inhibitor of Apoptosis Proteins

The neural crest cell (NCC) is a multipotent progenitor cell population that is sensitive to ethanol and is implicated in the Fetal Alcohol Spectrum Disorders (FASD). Studies have shown that sulforaphane (SFN) can prevent ethanol-induced apoptosis in NCCs. This study aims to investigate whether ethanol exposure can induce apoptosis in human NCCs (hNCCs) through epigenetically suppressing the expression of anti-apoptotic genes and whether SFN can restore the expression of anti-apoptotic genes and prevent apoptosis in ethanol-exposed hNCCs. We found that ethanol exposure resulted in a significant increase in the expression of DNMT3a and the activity of DNMTs. SFN treatment diminished the ethanol-induced upregulation of DNMT3a and dramatically reduced the activity of DNMTs in ethanol-exposed hNCCs. We also found that ethanol exposure induced hypermethylation at the promoter regions of two inhibitor of apoptosis proteins (IAP), NAIP and XIAP, in hNCCs, which were prevented by co-treatment with SFN. SFN treatment also significantly diminished ethanol-induced downregulation of NAIP and XIAP in hNCCs. The knockdown of DNMT3a significantly enhanced the effects of SFN on preventing the ethanol-induced repression of NAIP and XIAP and apoptosis in hNCCs. These results demonstrate that SFN can prevent ethanol-induced apoptosis in hNCCs by preventing ethanol-induced hypermethylation at the promoter regions of the genes encoding the IAP proteins and diminishing ethanol-induced repression of NAIP and XIAP through modulating DNMT3a expression and DNMT activity.

NO66 overexpression rescues ethanol-induced cell apoptosis in human AC16 cardiomyocytes by suppressing PTEN and activating the PI3K/Akt signaling

Previously, Nucleolar protein 66 (NO66) was reported to be closely associated with alcohol exposure-induced injury. However, the role of NO66 in alcohol-induced cytotoxicity remains unclear. In this study, we explored the potential effect and mechanism of NO66 on ethanol-induced apoptosis in human AC16 cardiomyocytes. The AC16 cell lines with NO66 and phosphatase and tensin homolog (PTEN) overexpression were constructed. Cell counting kit-8 (CCK-8), lactate dehydrogenase (LDH) assay, Annexin V-FITC/PI staining, and flow cytometry were used to evaluate the cell viability, membrane damage, and apoptosis, respectively. Quantitative real-time PCR (qRT-PCR) and western blot analysis were applied to measure mRNA and protein expression. The results showed that acute ethanol exposure markedly augmented cytotoxicity and reduced NO66 level in AC16 cardiomyocytes. Overexpression of NO66 partially reversed ethanol-induced apoptosis. NO66 upregulation reversed the decrease in phosphorylation of protein kinase B (Akt) and B-cell lymphoma-2/Bcl-2-associated x (Bcl-2/Bax) ratio and the increase in PTEN, p53, and caspase-3 activity induced by ethanol treatment. Meanwhile, the application of PI3K inhibitor (LY294002) and PTEN overexpression attenuated the inhibition efficiency of NO66 on cell apoptosis. In addition, PTEN overexpression weakened the effect of NO66 on PI3K/Akt activation, without affecting the level of NO66. Our data suggested that NO66 overexpression might play an anti-apoptotic role in ethanol-induced cell injury via reducing PTEN and upregulating the PI3K/Akt pathway.

TEOA Inhibits Proliferation and Induces DNA Damage of Diffuse Large B-Cell Lymphoma Cells Through Activation of the ROS-Dependent p38 MAPK Signaling Pathway

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of lymphoma, accounting for approximately 30% to 40% of non-Hodgkin’s lymphomas (NHL). The administration of rituximab significantly improved the outcomes of DLBCL; however, the unavoidable development of resistance limits the long-term efficacy. Therefore, a new generation of less toxic drugs with higher chemotherapy response is required to prevent or reverse chemoresistance. TEOA is a pentacyclic triterpenoid compound isolated from the roots of Actinidia eriantha. Studies have confirmed that TEOA has significant cytotoxicity on gastrointestinal cancer cells. However, there are no relevant reports on DLBCL cells. In this study, we investigated the potential molecular mechanism of the anticancer activity of TEOA in DLBCL cells. The results demonstrated that TEOA inhibited proliferation and induced apoptosis in time-and dose-dependent manners. TEOA induced reactive oxygen species (ROS) generation, which was reversed by N-acetyl cysteine (NAC). TEOA induced DNA damage, increased the level of γ-H2AX, and the phosphorylation of CHK1 and CHK2. In addition, TEOA induced the activation of the p38 MAPK pathway and pretreated with p38 inhibitor SB20358 or ROS scavenger could block TEOA-induced DNA damage. Taken together, these results suggest that ROS mediated activation of the p38 MAPK signal pathway plays an important role in initiating TEOA-induced DNA damage.

MicroRNA-135a Protects Against Ethanol-Induced Apoptosis in Neural Crest Cells and Craniofacial Defects in Zebrafish by Modulating the Siah1/p38/p53 Pathway

MicroRNAs (miRNAs) are small non-coding RNAs that are involved in various biological processes, including apoptosis, by regulating gene expression. This study was designed to test the hypothesis that ethanol-induced downregulation of miR-135a contributes to ethanol-induced apoptosis in neural crest cells (NCCs) by upregulating Siah1 and activating the p38 mitogen-activated protein kinase (MAPK)/p53 pathway. We found that treatment with ethanol resulted in a significant decrease in miR-135a expression in both NCCs and zebrafish embryos. Ethanol-induced downregulation of miR-135a resulted in the upregulation of Siah1 and the activation of the p38 MAPK/p53 pathway and increased apoptosis in NCCs and zebrafish embryos. Ethanol exposure also resulted in growth retardation and developmental defects that are characteristic of fetal alcohol spectrum disorders (FASD) in zebrafish. Overexpression of miRNA-135a significantly reduced ethanol-induced upregulation of Siah1 and the activation of the p38 MAPK/p53 pathway and decreased ethanol-induced apoptosis in NCCs and zebrafish embryos. In addition, ethanol-induced growth retardation and craniofacial defects in zebrafish larvae were dramatically diminished by the microinjection of miRNA-135a mimics. These results demonstrated that ethanol-induced downregulation of miR-135a contributes to ethanol-induced apoptosis in NCCs by upregulating Siah1 and activating the p38 MAPK/p53 pathway and that the overexpression of miRNA-135a can protect against ethanol-induced apoptosis in NCCs and craniofacial defects in a zebrafish model of FASD.

Hippocampal transcriptome analysis following maternal separation implicates altered RNA processing in a mouse model of fetal alcohol spectrum disorder

Background

Fetal alcohol spectrum disorders (FASD) are common, seen in 1–5% of the population in the USA and Canada. Children diagnosed with FASD are not likely to remain with their biological parents, facing early maternal separation and foster placements throughout childhood.

Methods

We model FASD in mice via prenatal alcohol exposure and further induce early life stress through maternal separation. We use RNA-seq followed by clustering of expression profiles through weighted gene co-expression network analysis (WGCNA) to analyze transcriptomic changes that result from the treatments. We use reverse transcription qPCR to validate these changes in the mouse hippocampus.

Results

We report an association between adult hippocampal gene expression and prenatal ethanol exposure followed by postnatal separation stress that is related to behavioral changes. Expression profile clustering using WGCNA identifies a set of transcripts, module 19, associated with anxiety-like behavior (r = 0.79, p = 0.002) as well as treatment group (r = 0.68, p = 0.015). Genes in this module are overrepresented by genes involved in transcriptional regulation and other pathways related to neurodevelopment. Interestingly, one member of this module, Polr2a, polymerase (RNA) II (DNA directed) polypeptide A, is downregulated by the combination of prenatal ethanol and postnatal stress in an RNA-Seq experiment and qPCR validation (q = 2e−12, p = 0.004, respectively).

Conclusions

Together, transcriptional control in the hippocampus is implicated as a potential underlying mechanism leading to anxiety-like behavior via environmental insults. Further research is required to elucidate the mechanism involved and use this insight towards early diagnosis and amelioration strategies involving children born with FASD.

N6-methyladenosine mediates arsenite-induced human keratinocyte transformation by suppressing p53 activation

N⁶-methyladenosine (m⁶A), the most abundant and reversible RNA modification, plays critical a role in tumorigenesis. However, whether m⁶A can regulate p53, a leading antitumor protein remains poorly understood. In this study, we explored the regulatory role of m⁶A on p53 activation using an arsenite-transformed keratinocyte model, the HaCaT-T cell line. We created the cell line by exposing human keratinocyte HaCaT cells to 1 μM arsenite for 5 months. We found that the cells exhibited an increased m⁶A level along with an aberrant expression of the methyltransferases, demethylase, and readers of m⁶A. Moreover, the cells exhibited decreased p53 activity and reduced p53 phosphorylation, acetylation, and transactivation with a high nucleus export rate of p53. Knockdown of the m⁶A methyltransferase, METTL3 significantly decreased m⁶A level, restoring p53 activation and inhibiting cellular transformation phenotypes in the arsenite-transformed cells. Further, using both a bioinformatics analysis and experimental approaches, we demonstrated that m⁶A downregulated the expression of the positive p53 regulator, PRDM2, through the YTHDF2-promoted decay of PRDM2 mRNAs. We showed that m⁶A upregulated the expression of the negative p53 regulator, YY1 and MDM2 through YTHDF1-stimulated translation of YY1 and MDM2 mRNA. Taken together, our study revealed the novel role of m⁶A in mediating arsenite-induced human keratinocyte transformation by suppressing p53 activation. This study further sheds light on the mechanisms of arsenic carcinogenesis via RNA epigenetics.

Sphingolipids and the link between alcohol and cancer

Epidemiological evidence underscores alcohol consumption as a strong risk factor for multiple cancer types, with liver cancer being most commonly associated with alcohol intake. While mechanisms linking alcohol consumption to malignant tumor development are not fully understood, the likely players in ethanol-induced carcinogenesis are genotoxic stress caused by formation of acetaldehyde, increased oxidative stress, and altered nutrient metabolism, including the impairment of methyl transfer reactions. Alterations of sphingolipid metabolism and associated signaling pathways are another potential link between ethanol and cancer development. In particular, ceramides are involved in the regulation of cellular proliferation, differentiation, senescence, and apoptosis and are known to function as important regulators of malignant transformation as well as tumor progression. However, to date, the cross-talk between ceramides and alcohol in cancer disease is largely an open question and only limited data are available on this subject. Most studies linking ceramide to cancer considered liver steatosis as the underlying mechanism, which is not surprising taking into consideration that ceramide pathways are an integral part of the overall lipid metabolism. This review summarizes the latest studies pointing to ceramide as an important mediator of cancer-promoting effects of chronic alcohol consumption and underscores the necessity of understanding the role of sphingolipids and lipid signaling in response to alcohol in order to prevent and/or successfully manage diseases caused by alcohol.

Li-Dan-He-Ji Improves Infantile Cholestasis Hepatopathy Through Inhibiting Calcium-Sensing Receptor-Mediated Hepatocyte Apoptosis

Infantile cholestatic hepatopathy (ICH) is a clinical syndrome characterized by the accumulation of cytotoxic bile acids in infancy, leading to serious liver cirrhosis or liver failure. The aetiology of ICH is complicated and some of them is unknown. Regardless of the aetiology, the finial pathology of ICH is hepatocyte apoptosis caused by severe and persistent cholestasis. It is already known that activation of calcium-sensing receptor (CaSR) could lead to the apoptosis of cardiomyocytes. However, the mechanism by CaSR-mediated cholestasis-related hepatocyte apoptosis is not fully understood. Li-Dan-He-Ji (LDHJ), a Traditional Chinese Medicine prescription, was developed to treat ICH. Another aim of this study was to investigate the possible mechanisms of LDHJ in cholestasis-related hepatocyte apoptosis. Using the primary hepatocytes, we first investigated the molecular mechanism of CaSR-mediated hepatocyte apoptosis in cholestasis. Then we prepared LDHJ granules and used ultra-high-performance liquid chromatography to identify the predominant drugs; confirmed the stability of the main substances; and for cell experiments screened forsythoside-A, emodin and chlorogenic acid as the three active substances of LDHJ granules. In the young rats with ANIT-induced intrahepatic cholestasis and the primary hepatocytes with TCDC-induced cholestasis-related hepatocyte apoptosis, the levels of liver injury and cholestasis-related biomarkers, calcium-sensing receptor (CaSR), hepatocyte apoptosis, Bax/Bcl-2 ratio, Cytochrome-C, caspase-3, phosphorylated-c-Jun NH₂-terminal kinase (p-JNK)/JNK, and p-P38/P38 were all increased, while the levels of p-extracellular signal-regulated kinase (p-ERK)/ERK were decreased. However, LDHJ granules and its three active substances effectively reversed these changes. Furthermore, the three active substances reduced the increases in the intracellular calcium concentration ([Ca²⁺]_i) and ROS levels and attenuated the dissipation of the mitochondria membrane potential in the TCDC-induced primary hepatocytes. The opposite results were obtained from the TCDC-induced primary hepatocytes treated with an agonist of CaSR (GdCl₃) plus forsythoside-A, emodin or chlorogenic acid. Based on the results from in vivo and in vitro studies, LDHJ functions as an antagonist of CaSR to regulate hepatocyte apoptosis in cholestasis through the mitochondrial pathway and mitogen-activated protein kinase pathway.

Downregulation of Siah1 promotes colorectal cancer cell proliferation and migration by regulating AKT and YAP ubiquitylation and proteasome degradation

Background

Colorectal cancer (CRC) is one of the most common malignant tumors in the world. Siah E3 ubiquitin protein ligase 1 (Siah1) has been identified as a tumor suppressor gene and plays an important role in the development of malignant tumors. However, the potential role and molecular mechanism of Siah1 in the development and progression of CRC is still unclear.

Methods

To explore the role and molecular mechanism of Siah1 in the development and progression of CRC, we examined the expression of Siah1 in CRC tissue samples and analyzed its association with progression and prognosis in CRC. In addition, overexpression and knockdown of Siah1 was used to investigate its activity in CRC cells. We also use bioinformatics to analyze and verify the significant roles of Siah1 in critical signaling pathways of CRC.

Results

We found that the expression of Siah1 was significantly downregulated in CRC tissues, and low expression of Siah1 was associated with aggressive TNM staging and poor survival of CRC patients. Moreover, we revealed that overexpression of Siah1 in CRC cells markedly inhibited CRC cell proliferation and invasion in vitro and in vivo, while knockdown of Siah1 enhanced CRC cell proliferation and invasion. Furthermore, we found that Siah1 prohibited cell proliferation and invasion in CRC partially through promoting AKT (the serine-threonine protein kinase) and YAP (yes associated protein) ubiquitylation and proteasome degradation to regulate the activity of MAPK(mitogen-activated protein kinase 1), PI3K-AKT (phosphatidylinositol 3-kinase-the serine-threonine protein kinase) and Hippo signaling pathways.

Conclusions

These findings suggested that Siah1 is a novel potential prognostic biomarker and plays a tumor suppressor role in the development and progression of CRC.

Alcohol-mediated calcium signals dysregulate pro-survival Snai2/PUMA/Bcl2 networks to promote p53-mediated apoptosis in avian neural crest progenitors

BACKGROUND

Prenatal alcohol exposure causes distinctive craniofacial anomalies that arise, in part, from the apoptotic elimination of neural crest (NC) progenitors that form the face. This vulnerability of NC to alcohol is puzzling as they normally express the transcriptional repressor Snail1/2 (in chick Snai2), which suppresses apoptosis and promotes their migration. Here, we investigate alcohol's impact upon Snai2 function.

METHODS

Chick cranial NC cells were treated with acute alcohol (52 mM, 2 hr). We evaluated NC migration, gene expression, proliferation, and apoptosis thereafter.

RESULTS

Transient alcohol exposure induced Snai2 (191% ± 23%; p = .003) and stimulated NC migration (p = .0092). An alcohol-induced calcium transient mediated this Snai2 induction, and BAPTA-AM blocked whereas ionomycin mimicked these pro-migratory effects. Alcohol suppressed CyclinD1 protein content (59.1 ± 12%, p = .007) and NC proliferation (19.7 ± 5.8%, p < .001), but these Snai2-enriched cells still apoptosed in response to alcohol. This was explained because alcohol induced p53 (198 ± 29%, p = .023), and the p53 antagonist pifithrin-α prevented their apoptosis. Moreover, alcohol counteracted Snai2's pro-survival signals, and Bcl2 was repressed (68.5 ± 6.0% of controls, p = .016) and PUMA was not induced, while ATM (1.32-fold, p = .01) and PTEN (1.30-fold, p = .028) were elevated.

CONCLUSIONS

Alcohol's calcium transient uncouples the Snai2/p53 regulatory loop that normally prevents apoptosis during EMT. This represents a novel pathway in alcohol's neurotoxicity, and complements demonstrations that alcohol suppresses PUMA in mouse NC. We propose that the NCs migratory behavior, and their requirement for Snai2/p53 co-expression, makes them vulnerable to stressors that dysregulate Snai2/p53 interactions, such as alcohol.

MicroRNA-34a mediates ethanol-induced impairment of neural differentiation of neural crest cells by targeting autophagy-related gene 9a

Neural crest cells (NCCs) are multipotent progenitor cells that are sensitive to ethanol and are implicated in Fetal Alcohol Spectrum Disorders (FASD). The objective of this study is to test whether ethanol exposure can inhibit the neural differentiation of NCCs by inhibiting autophagy and whether miR-34a is involved in ethanol-induced inhibition of autophagy in NCCs. We found that ethanol exposure resulted in the inhibition of neural differentiation of NCCs. Exposure to ethanol also significantly decreased autophagy in NCCs, as indicated by a decreased LC3II/I ratio and an elevated expression of p62 protein. Knockdown of p62 restored the expression of the neurogenesis genes, NF and Mash1, in ethanol-exposed NCCs, suggesting that ethanol exposure can inhibit the neural differentiation of NCCs by inhibiting autophagy. We also found that ethanol exposure resulted in a significant increase in miR-34a expression in NCCs. Inhibition of miR-34a restored the expression of Atg9a, a direct target of miR-34a and significantly decreased ethanol-induced inhibition of autophagy in NCCs. Down-regulation of miR-34a also prevented ethanol-induced inhibition of neural differentiation of NCCs. These results demonstrate that ethanol-induced inhibition of neural differentiation of NCCs is mediated by the miR-34a through targeting Atg9a.

Effects of ethanol on human periodontal ligament fibroblasts subjected to static compressive force

Consumption of toxic substances such as alcohol is widespread in the general population and thus also in patients receiving orthodontic treatment. Since human periodontal ligament (hPDL) fibroblasts play a key role in orthodontic tooth movement (OTM) by expressing cytokines and chemokines, we wanted to clarify whether ethanol modulates the physiological activity and expression pattern of hPDL fibroblasts during static compressive force application. We pre-incubated hPDL fibroblasts for 24 h with different ethanol concentrations, corresponding to casual (0.041% blood alcohol concentration [BAC], % by volume) and excessive (0.179%) alcohol consumption. At each ethanol concentration, we incubated the cells for another 48 h with and without an additional physiological compressive force of 2 g/cm² occurring during orthodontic tooth movement in compression areas of the periodontal ligament. Thereafter, we analyzed expression and secretion of genes and proteins involved in OTM regulation by RT-qPCR and ELISA. We also performed co-culture experiments to observe hPDL-fibroblast-mediated osteoclastogenesis. We observed no effects of ethanol on cytotoxicity or cell viability of hPDL fibroblasts in the applied concentrations. Ethanol showed an enhancing effect on angiogenesis and activity of alkaline phosphatase. Simultaneously, ethanol reduced the induction of IL-6 and increased prostaglandin E₂ synthesis as well as hPDL-fibroblast-mediated osteoclastogenesis without affecting the RANK-L/OPG-system. hPDL fibroblasts thus seem to be a cell type quite resistant to ethanol, as no cytotoxic effects or influence on cell viability were detected. High ethanol concentrations, however, seem to promote bone formation and angiogenesis. Ethanol at 0.179% also enhanced hPDL-induced osteoclastogenesis, indicating increased bone resorption and thus tooth movement velocity to be expected during orthodontic therapy.

Exon level machine learning analyses elucidate novel candidate miRNA targets in an avian model of fetal alcohol spectrum disorder

Gestational alcohol exposure causes fetal alcohol spectrum disorder (FASD) and is a prominent cause of neurodevelopmental disability. Whole transcriptome sequencing (RNA-Seq) offer insights into mechanisms underlying FASD, but gene-level analysis provides limited information regarding complex transcriptional processes such as alternative splicing and non-coding RNAs. Moreover, traditional analytical approaches that use multiple hypothesis testing with a false discovery rate adjustment prioritize genes based on an adjusted p-value, which is not always biologically relevant. We address these limitations with a novel approach and implemented an unsupervised machine learning model, which we applied to an exon-level analysis to reduce data complexity to the most likely functionally relevant exons, without loss of novel information. This was performed on an RNA-Seq paired-end dataset derived from alcohol-exposed neural fold-stage chick crania, wherein alcohol causes facial deficits recapitulating those of FASD. A principal component analysis along with k-means clustering was utilized to extract exons that deviated from baseline expression. This identified 6857 differentially expressed exons representing 1251 geneIDs; 391 of these genes were identified in a prior gene-level analysis of this dataset. It also identified exons encoding 23 microRNAs (miRNAs) having significantly differential expression profiles in response to alcohol. We developed an RDAVID pipeline to identify KEGG pathways represented by these exons, and separately identified predicted KEGG pathways targeted by these miRNAs. Several of these (ribosome biogenesis, oxidative phosphorylation) were identified in our prior gene-level analysis. Other pathways are crucial to facial morphogenesis and represent both novel (focal adhesion, FoxO signaling, insulin signaling) and known (Wnt signaling) alcohol targets. Importantly, there was substantial overlap between the exomes themselves and the predicted miRNA targets, suggesting these miRNAs contribute to the gene-level expression changes. Our novel application of unsupervised machine learning in conjunction with statistical analyses facilitated the discovery of signaling pathways and miRNAs that inform mechanisms underlying FASD.

The role of p53 in developmental syndromes

While it is well appreciated that loss of the p53 tumor suppressor protein promotes cancer, growing evidence indicates that increased p53 activity underlies the developmental defects in a wide range of genetic syndromes. The inherited or de novo mutations that cause these syndromes affect diverse cellular processes, such as ribosome biogenesis, DNA repair, and centriole duplication, and analysis of human patient samples and mouse models demonstrates that disrupting these cellular processes can activate the p53 pathway. Importantly, many of the developmental defects in mouse models of these syndromes can be rescued by loss of p53, indicating that inappropriate p53 activation directly contributes to their pathogenesis. A role for p53 in driving developmental defects is further supported by the observation that mouse strains with broad p53 hyperactivation, due to mutations affecting p53 pathway components, display a host of tissue-specific developmental defects, including hematopoietic, neuronal, craniofacial, cardiovascular, and pigmentation defects. Furthermore, germline activating mutations in TP53 were recently identified in two human patients exhibiting bone marrow failure and other developmental defects. Studies in mice suggest that p53 drives developmental defects by inducing apoptosis, restraining proliferation, or modulating other developmental programs in a cell type-dependent manner. Here, we review the growing body of evidence from mouse models that implicates p53 as a driver of tissue-specific developmental defects in diverse genetic syndromes.

Cyanidin-3- O-glucoside at Low Doses Protected against 3-Chloro-1,2-propanediol Induced Testis Injury and Improved Spermatogenesis in Male Rats

In recent decades, the capability of mankind spermatogenesis is declining due to various threats. Anthocyanins as colorful polyphenols possess beneficial functions for the organisms, including Leydig cells, but their effects on male spermatogenesis remain underexplored. In our study, the protective effect of cyanidin-3- O-glucoside (C3G) was investigated on the 3-chloro-1,2-propanediol (3-MCPD) caused rat spermatogenic disorders. At low doses, C3G improved the number and motility of the sperms, alleviating the seminiferous tubule injury. Interestingly, C3G showed no influence on sexual hormone but increased the androgen receptor expression. Meanwhile, C3G reduced the oxidative stress and number of apoptotic cells and promoted the integrity of the blood-testis barrier in the testis. Additionally, C3G mediated the activation of p-ERK, p-JNK, and p53, which are related to the protection of Sertoli cells and spermatogenesis. In conclusion, C3G protected against the 3-MCPD caused testis damage and spermatogenic disorders under appropriate doses, which indicates the potential protection of anthocyanins on male reproduction.

Tp53 Mutation Inhibits Ubiquitination and Degradation of WISP1 via Down-Regulation of Siah1 in Pancreatic Carcinogenesis

Wnt1 inducible signaling pathway protein-1 (WISP1) may play an important role in promoting carcinogenesis. However, the biological function and underlying mechanism of WISP1 in pancreatic carcinogenesis still remains enigmatic. In this study, immunochemistry staining showed that protein levels of WISP1 were more significantly upregulated in pancreatic ductal adenocarcinoma (PDAC) tissues with Tp53 mutation than in PDAC tissues with Tp53 wild-type. In addition, a significant correlation was observed between increased malignant phenotype of tumors from well-differentiated adenocarcinoma tissues to moderately- or poorly-differentiated adenocarcinoma tissues shifting from cytoplasmic expression to nuclear accumulation of WISP1. Interestingly, WISP1 expression was correlated with the poor prognosis in PDAC patients with Tp53 mutation. Also, the biological function analysis showed that WISP1 may act as a potential oncogene in PDAC cells. In addition, immunofluorescence analysis showed that Tp53 mutation promoted WISP1 expression in PanIN and PDAC cells, while Siah E3 Ubiquitin Protein Ligase 1 (Siah1) inhibited WISP1 expression in PDAC cells. Moreover, through immunoprecipitation, immunoblotting analysis, in vitro binding assay, and ubiquitination assay, we found that Tp53 mutation inhibited ubiquitination and degradation of Siah1-dependent WISP1. Therefore, Tp53 mutation-Siah1-WISP1 is a new signaling pathway, playing an important role in pancreatic carcinogenesis.

Acute dose of melatonin via Nrf2 dependently prevents acute ethanol-induced neurotoxicity in the developing rodent brain

BACKGROUND

Melatonin is a well-known potent endogenous antioxidant pharmacological agent with significant neuroprotective actions. Here in the current study, we explored the nuclear factor erythroid 2-related factor 2 (Nrf2) gene-dependent antioxidant mechanism underlying the neuroprotective effects of the acute melatonin against acute ethanol-induced elevated reactive oxygen species (ROS)-mediated neuroinflammation and neurodegeneration in the developing rodent brain.

METHODS

In vivo rat pups were co-treated with a single dose of acute ethanol (5 g/kg, subcutaneous (S.C.)) and a single dose of acute melatonin (20 mg/kg, intraperitoneal (I.P.)). Four hours after a single S.C. and I.P. injections, all of the rat pups were sacrificed for further biochemical (Western blotting, ROS- assay, LPO-assay, and immunohistochemical) analyses. In order to corroborate the in vivo results, we used the in vitro murine-hippocampal HT22 and microglial BV2 cells, which were subjected to knockdown with small interfering RNA (siRNA) of Nrf2 genes and exposed with melatonin (100 μM) and ethanol (100 mM) and proceed for further biochemical analyses.

RESULTS

Our biochemical, immunohistochemical, and immunofluorescence results demonstrate that acute melatonin significantly upregulated the master endogenous antioxidant Nrf2 and heme oxygenase-1, consequently reversing the acute ethanol-induced elevated ROS and oxidative stress in the developing rodent brain, and in the murine-hippocampal HT22 and microglial BV2 cells. In addition, acute melatonin subsequently reduced the activated MAPK-p-P38-JNK pathways and attenuated neuroinflammation by decreasing the expression of activated gliosis and downregulated the p-NF-K-B/p-IKKβ pathway and decreased the expression levels of other inflammatory markers in the developing rodent brain and BV2 cells. Of note, melatonin acted through the Nrf2-dependent mechanism to attenuate neuronal apoptosis in the postnatal rodent brain and HT22 cells. Immunohistofluorescence results also showed that melatonin prevented ethanol-induced neurodegeneration in the developing rodent brain. The in vitro results indicated that melatonin induced neuroprotection via Nrf2-dependent manner and reduced ethanol-induced neurotoxicity.

CONCLUSIONS

The pleiotropic and potent neuroprotective antioxidant characteristics of melatonin, together with our in vivo and in vitro findings, suppose that acute melatonin could be beneficial to prevent and combat the acute ethanol-induced neurotoxic effects, such as elevated ROS, neuroinflammation, and neurodegeneration in the developing rodent brain.

Iron overload induces G1 phase arrest and autophagy in murine preosteoblast cells

This study aimed to investigate the cell cycle arrest and autophagy induced by iron overload in MC3T3-E1 cells. MC3T3-E1 cells were cultured in different concentrations of ferric ammonium citrate (FAC), and Perls' Prussian blue reaction was used to detect the iron levels of the cells. CCK-8 assays were used to detect the growth of MC3T3-E1. The level of reactive oxygen species (ROS) within cells was investigated with DCFH-DA. PI staining was used to analyze the cell cycle distribution of MC3T3-E1 cells. Finally, the expression levels of cell cycle related proteins, autophagy related proteins, AKT, p38 MAPK, Stat3, and their downstream proteins were detected with Western blot assays. The results showed that the iron levels of MC3T3-E1 cells increased with increasing concentrations of FAC. High levels of ferric ion inhibited proliferation of MC3T3-E1 cells and increased their ROS levels. Additionally, iron overload induced G1arrest in MC3T3-E1 cells and down-regulated the expression of Cyclin D₁ , Cyclin D₃ , CDK2, CDK4 and CDK6, but up-regulated p27 Kip1. In addition, the expression levels of Beclin-1 and LC3 II increased, but that of p62 decreased. Further experiments showed that the phosphorylation of AKT and its downstream proteins p-GSK-3β(Ser9) and p-mTOR (Ser2448) were decreased. The levels of p-p38 and p53 were up-regulated while those of cdc25A and p-ERK 1/2 were down-regulated. Phosphorylation of Stat3 and its downstream proteins was all decreased. These results show that iron overload generates ROS, blocks the PI3K/AKT and Jak/Stat3 signal pathways, and activates p38 MAPK, subsequently inducing G1 arrest and autophagy in MC3T3-E1 cells.

Sulforaphane restores acetyl-histone H3 binding to Bcl-2 promoter and prevents apoptosis in ethanol-exposed neural crest cells and mouse embryos

Sulforaphane (SFN) is an isothiocyanate derived from cruciferous vegetables. SFN's cytoprotective properties have been demonstrated in several models associated with a variety of disorders. Our recent studies have shown that SFN protects against ethanol-induced oxidative stress and apoptosis in neural crest cells (NCCs), an ethanol-sensitive cell population implicated in Fetal Alcohol Spectrum Disorders (FASD). This study is designed to test the hypothesis that SFN can prevent ethanol-induced apoptosis in NCCs by inhibiting HDAC and increasing histone acetylation at the Bcl-2 promoter. We found that exposure to 50mM ethanol resulted in a significant increase in HDAC activities in NCCs. Treatment with SFN decreased the activities of HDAC in ethanol-exposed NCCs. We also found that SFN treatment significantly increased the expression of acetyl-histone H3 in NCCs treated with ethanol. ChIP-qPCR assay revealed that ethanol exposure significantly decreased acetyl-histone H3 binding to the Bcl-2 promoter while supplementing with SFN reversed the ethanol-induced reduction in acetyl-histone H3 binding to the Bcl-2 promoter. In addition, SFN treatment restored the expression of Bcl-2 in ethanol-exposed NCCs and diminished ethanol-induced apoptosis in NCCs. Treatment with SFN also significantly diminished apoptosis in mouse embryos exposed to ethanol in vivo. These results demonstrate that SFN can epigenetically restore the expression of Bcl-2 and attenuate ethanol-induced apoptosis by increasing histone acetylation at the Bcl-2 promoter and suggest that SFN may prevent FASD through epigenetic regulation of the expression of anti-apoptotic genes.

In Utero Alcohol Exposure and the Alteration of Histone Marks in the Developing Fetus: An Epigenetic Phenomenon of Maternal Drinking

Ethanol is well known for its teratogenic effects during fetal development. Maternal alcohol consumption allows the developing fetus to experience the detrimental effects of alcohol exposure. Alcohol-mediated teratogenic effects can vary based on the dosage and the length of exposure. The specific mechanism of action behind this teratogenic effect is still unknown. Previous reports demonstrated that alcohol participates in epigenetic alterations, especially histone modifications during fetal development. Additional research is necessary to understand the correlation between major epigenetic events and alcohol-mediated teratogenesis such as that observed in fetal alcohol spectrum disorder (FASD). Here, we attempted to collect all the available information concerning alcohol-mediated histone modifications during gestational fetal development. We hope that this review will aid researchers to further examine the issues associated with ethanol exposure.

Fetal Alcohol Exposure: The Common Toll

Alcohol has always been present in human life, and currently it is estimated that 50% of women of childbearing age consume alcohol. It has become increasingly clear over the last years that alcohol exposure during fetal development can have detrimental effects on various organ systems, and these effects are exerted by alcohol through multiple means, including effects on free radical formation, cellular apoptosis, as well as gene expression. Fetal alcohol exposure can lead to a spectrum of short term as well as long-term problems, with Fetal Alcohol Syndrome being on the more severe end of that spectrum. This syndrome is morbid, yet preventable, and is characterized by midfacial hypoplasia, thin upper lip, widely spaced small eyes, long smooth philtrum and inner epicanthal folds. Other findings include growth restriction as well as various neurodevelopmental abnormalities. This article is the first comprehensive review combining the molecular as well as the gross physiological and anatomical effects of alcohol exposure during pregnancy on various organ systems in the body. Our knowledge of these various mechanisms is crucial for our understanding of how alcohol exposure during fetal development can lead to its detrimental effects.

Toxicogenomic analysis identifies the apoptotic pathway as the main cause of hepatotoxicity induced by tributyltin

Tributyltin (TBT) is one of the most widely used organotin biocides, which has severe endocrine-disrupting effects on marine species and mammals. Given that TBT accumulates at higher levels in the liver than in any other organ, and it acts mainly as a hepatotoxic agent, it is important to clearly delineate the hepatotoxicity of TBT. However, most of the available studies on TBT have focused on observations at the cellular level, while studies at the level of genes and proteins are limited; therefore, the molecular mechanisms of TBT-induced hepatotoxicity remains largely unclear. In the present study, we applied a toxicogenomic approach to investigate the effects of TBT on gene expression in the human normal liver cell line HL7702. Gene expression profiling identified the apoptotic pathway as the major cause of hepatotoxicity induced by TBT. Flow cytometry assays confirmed that medium- and high-dose TBT treatments significantly increased the number of apoptotic cells, and more cells underwent late apoptosis in the high-dose TBT group. The genes encoding heat shock proteins (HSPs), kinases and tumor necrosis factor receptors mediated TBT-induced apoptosis. These findings revealed novel molecular mechanisms of TBT-induced hepatotoxicity, and the current microarray data may also provide clues for future studies.