Role of lncRNAs and circRNAs in Orofacial Clefts.

Different modes of gene regulation, such as histone modification, transcription factor binding, DNA methylation, and microRNA (miRNA) expression, are critical for the spatiotemporal expression of genes in developing orofacial tissues. Aberrant regulation in any of these modes may contribute to orofacial defects. Noncoding RNAs (ncRNAs), such as long ncRNAs (lncRNAs) and circular RNAs (circRNAs), have been shown to alter miRNA expression, and are thus emerging as novel contributors to gene regulation. Some of these appear to function as 'miRNA sponges', thereby diminishing the availability of these miRNAs to inhibit the expression of target genes. Such ncRNAs are also termed competitive endogenous RNAs (ceRNAs). Here, we examine emerging data that shed light on how lncRNAs and circRNAs may alter miRNA regulation, thus affecting orofacial development and potentially contributing to orofacial clefting.

MicroRNA-Mediated Regulation of BMP Signaling in the Developing Neural Tube.

BACKGROUND: Neural tube (NT) morphogenesis is reliant on the proper temporospatial expression of numerous genes and synchronized crosstalk between diverse signaling cascades and gene regulatory networks governing key cellular processes. MicroRNAs (miRNAs), a group of small non-coding regulatory RNAs, execute defining roles in directing key canonical pathways during embryogenesis. OBJECTIVE: In order to comprehend the mechanistic underpinnings of miRNA regulation of NT morphogenesis, we have identified in the current study various miRNAs and their target mRNAs associated with BMP signaling during critical stages of neurulation. METHODS: We previously demonstrated the expression of several miRNAs during the critical stages of neurulation (gestational days (GD) 8.5, 9.0, and 9.5) employing high-sensitivity, high-coverage microarrays. In the present study, bioinformatic analyses were used to identify miRNAs differentially expressed (DE) in the embryonic NT that target messenger RNAs (mRNAs) associated with the bone morphogenetic protein (BMP) signaling pathway. RNAs extracted from the developing NT were hybridized to both miRNA and mRNA arrays to evaluate miRNA-mRNA interactions. RESULTS: Bioinformatic analysis identified several DE miRNAs that targeted mRNAs encoding members of (and proteins associated with) the BMP signaling pathway - a signaling cascade central to normal NT development. CONCLUSION: Identification of the miRNAs and their mRNA targets associated with BMP signaling facilitates a better understanding of the crucial epigenetic mechanisms underlying normal NT development as well as the pathogenesis of NT defects. The current study supports the notion that miRNAs function as key regulators of neural tube morphogenesis via modulation of the BMP signaling cascade. Altered expression of these miRNAs during neurulation may therefore result in NT defects.

Spatiotemporal Expression and Functional Analysis of miRNA-22 in the Developing Secondary Palate.

OBJECTIVE: Normal development of the embryonic orofacial region requires precise spatiotemporal coordination between numerous genes. MicroRNAs represent small, single-stranded, non-coding molecules that regulate gene expression. This study examines the role of microRNA-22 (miR-22) in murine orofacial ontogeny. METHODS: Spatiotemporal and differential expression of miR-22 (mmu-miR-22-3p) within the developing secondary palate was determined by in situ hybridization and quantitative real-time PCR, respectively. Bioinformatic approaches were used to predict potential mRNA targets of miR-22 and analyze their association with cellular functions indispensable for normal orofacial ontogeny. An in vitro palate organ culture system was used to assess the role of miR-22 in secondary palate development. RESULTS: There was a progressive increase in miR-22 expression from GD12.5 to GD14.5 in palatal processes. On GD12.5 and GD13.5, miR-22 was expressed in the future oral, nasal, and medial edge epithelia. On GD14.5, miR-22 expression was observed in the residual midline epithelial seam (MES), the nasal epithelium and the mesenchyme, but not in the oral epithelium. Inhibition of miR-22 activity in palate organ cultures resulted in failure of MES removal. Bioinformatic analyses revealed potential mRNA targets of miR-22 that may play significant roles in regulating apoptosis, migration, and/or convergence/extrusion, developmental processes that modulate MES removal during palatogenesis. CONCLUSIONS: Results from the current study suggest a key role for miR-22 in the removal of the MES during palatogenesis and that miR-22 may represent a potential contributor to the etiology of cleft palate.

New insights into the antiviral activity of nordihydroguaiaretic acid: Inhibition of dengue virus serotype 1 replication.

BACKGROUND: Dengue virus (DENV) is considered one of the most important pathogens in the world causing 390 million infections each year. Currently, the development of vaccines against DENV presents some shortcomings and there is no antiviral therapy available for its infection. An important challenge is that both treatments and vaccines must be effective against all four DENV serotypes. Nordihydroguaiaretic acid (NDGA), isolated from Larrea divaricata Cav. (Zygophyllaceae) has shown a significant inhibitory effect on a broad spectrum of viruses, including DENV serotypes 2 and 4. PURPOSE: We evaluated the in vitro virucidal and antiviral activity of NDGA on DENV serotype 1 (DENV1), including the study of its mechanism of action, to provide more evidence on its antiviral activity. METHODS: The viability of viral particles was quantified by the plaque-forming unit reduction method. NDGA effects on DENV1 genome and viral proteins were evaluated by qPCR and immunofluorescence, respectively. Lysosomotropic activity was assayed using acridine orange and neutral red dyes. RESULTS: NDGA showed in vitro virucidal and antiviral activity against DENV1. The antiviral effect would be effective within the first 2 h after viral internalization, when the uncoating process takes place. In addition, we determined by qPCR that NDGA decreases the amount of intracellular RNA of DENV1 and, by immunofluorescence, the number of cells infected. These results indicate that the antiviral effect of NDGA would have an intracellular mechanism of action, which is consistent with its ability to be incorporated into host cells. Considering the inhibitory activity of NDGA on the cellular lipid metabolism, we compared the antiviral effect of two inhibitors acting on two different pathways of this type of metabolism: 1) resveratrol that inhibits the sterol regulatory element of binding proteins, and 2) caffeic acid that inhibits the 5-lipoxygenase (5-LOX) enzyme. Only caffeic acid produced an inhibitory effect on DENV1 infection. We studied the lysosomotropic activity of NDGA on host cells and found, for the first time, that this compound inhibited the acidification of cell vesicles which would prevent DENV1 uncoating process. CONCLUSION: The present work contributes to the knowledge of NDGA activity on DENV. We describe its activity on DENV1, a serotype different to those that have been already reported. Moreover, we provide evidence on which stage/s of the viral replication cycle NDGA exerts its effects. We suggest that the mechanism of action of NDGA on DENV1 is related to its lysosomotropic effect, which inhibits the viral uncoating process.

MicroRNAs as epigenetic regulators of orofacial development.

Environmental and genetic factors contribute significantly to the etiology of orofacial clefting, which is one of the most common of human congenital craniofacial malformations. Current biological thought now recognizes that epigenetics represents a fundamental contributing process in embryogenesis. Indeed, many of the mechanisms whereby environmental insults affect key pathways crucial for proper embryonic growth and development are increasingly thought to be mediated via the epigenome. Epigenetic regulators, such as microRNAs (miRNAs), play vital roles in the ontogeny of the orofacial region. Evidence for this comes from conditional knockouts of Dicer or DGCR8, genes encoding key enzymes in the miRNA biosynthetic machinery, in neural crest cells. Such knockouts result in a range of craniofacial/orofacial anomalies, including cleft palate and cleft lip. Epigenetic pathways may thus represent key vehicles in the regulation, and misregulation, of gene expression during normal and abnormal orofacial embryogenesis. Significant strides have been made in the last decade in identifying miRNAs and their target genes involved in lip and palate morphogenesis. Such morphogenetic processes include apoptosis, cell proliferation, cell differentiation, and epithelial-mesenchymal transition (EMT). While some of the miRNA-target gene interactions have been functionally validated, many exhibit causal relationships that await functional confirmation. A plethora of genes associated with cleft palate/cleft lip have now been identified that provides a veritable treasure trove of information that could be harnessed to identify novel miRNA candidates for further analysis. In this review, we summarize studies identifying miRNAs involved in various aspects of lip and palate morphogenesis and whose aberrant expression may result in orofacial clefts.

MicroRNAs as Biomarkers for Birth Defects.

It is estimated that 2-4% of live births will have a birth defect (BD). The availability of biomarkers for the prenatal detection of BDs will facilitate early risk assessment, prompt medical intervention and ameliorating disease severity. miRNA expression levels are often found to be altered in many diseases. There is, thus, a growing interest in determining whether miRNAs, particularly extracellular miRNAs, can predict, diagnose, or monitor BDs. These miRNAs, typically encapsulated in exosomes, are released by cells (including those of the fetus and placenta) into the extracellular milieu, such as blood, urine, saliva and cerebrospinal fluid, thereby enabling interaction with target cells. Exosomal miRNAs are stable, protected from degradation, and retain functionality. The observation that placental and fetal miRNAs can be detected in maternal serum, provides a strong rationale for adopting miRNAs as noninvasive prenatal biomarkers for BDs. In this mini-review, we examine the current state of research involving the use of miRNAs as prognostic and diagnostic biomarkers for BD.

Riga-Fede disease: A systematic review and report of two cases.

AIM: The term Riga-Fede disease has been used historically to describe traumatic ulceration that occurs on the ventral surface of tongue, buccal mucosa, gum or floor of the tongue in newborns and infants. It is most often associated with natal and neonatal teeth in newborns. The painful symptoms may be absent or acute, up to the point of preventing the baby from feeding. The aim of this work is to offer a description of the therapeutic solutions for the treatment of this pathological condition, with a review of the literature and the report of two cases. MATERIALS: A systematic review of the literature of articles presenting Riga-Fede Disease associated with natal and neonatal teeth was performed following the PRISMA protocol (Prefered Reporting Items for Systematic Reviews and Meta-Analyses). This bibliographic search was performed through two databases, PubMed and Google Scholar. CONCLUSION: Extraction and ameloplasty are the most effective treatments in the resolution of the Riga-Fede disease associated with natal/neonatal teeth. In the case of high dental mobility, resulting in an increased risk of exfoliation and possible tooth ingestion/inhalation, extraction is the therapeutic treatment of choice. When nutrition is not compromised, ameloplasty is the treatment of choice, as it is less invasive and more conservative.

Gestational folate deficiency alters embryonic gene expression and cell function.

Folic acid is a nutrient essential for embryonic development. Folate deficiency can cause embryonic lethality or neural tube defects and orofacial anomalies. Folate receptor 1 (Folr1) is a folate binding protein that facilitates the cellular uptake of dietary folate. To better understand the biological processes affected by folate deficiency, gene expression profiles of gestational day 9.5 (gd9.5) Folr1-/- embryos were compared to those of gd9.5 Folr1+/+ embryos. The expression of 837 genes/ESTs was found to be differentially altered in Folr1-/- embryos, relative to those observed in wild-type embryos. The 837 differentially expressed genes were subjected to Ingenuity Pathway Analysis. Among the major biological functions affected in Folr1-/- mice were those related to 'digestive system development/function', 'cardiovascular system development/function', 'tissue development', 'cellular development', and 'cell growth and differentiation', while the major canonical pathways affected were those associated with blood coagulation, embryonic stem cell transcription and cardiomyocyte differentiation (via BMP receptors). Cellular proliferation, apoptosis and migration were all significantly affected in the Folr1-/- embryos. Cranial neural crest cells (NCCs) and neural tube explants, grown under folate-deficient conditions, exhibited marked reduction in directed migration that can be attributed, in part, to an altered cytoskeleton caused by perturbations in F-actin formation and/or assembly. The present study revealed that several developmentally relevant biological processes were compromised in Folr1-/- embryos.

Proposal of a pathway for enteric virus groups detection as indicators of faecal contamination to enhance the evaluation of microbiological quality in freshwater in Argentina.

An environmental survey was conducted in order to assess the frequency of detection of picobirnavirus (PBV), human adenovirus (HAdV) and infective enterovirus (iEV) as indicators of faecal contamination in freshwater, and to determine their potential as reporters of the presence of other enteric viruses, such as group A rotavirus (RVA). The study was carried out over a three-year period (2013-2015) in the San Roque Dam, Córdoba, Argentina. The overall frequency detection was 62.9% for PBV, 64.2% for HAdV and 70.4% for iEV. No significant differences were observed in the rates of detection for any of these viruses through the years studied, and a seasonal pattern was not present. Whenever there was RVA detection in the samples analyzed, there was also detection of iEV and/or HAdV and/or PBV. At least one of the viral groups analyzed was demonstrated in the 100% of the samples with faecal coliforms values within the guideline limits. In this setting, especially in those samples which reveal faecal indicator bacteria within the guideline limit, we propose to carry out a pathway, involving PBV, HAdV and iEV detection in order to enhance the evaluation of microbiological quality in freshwater in Argentina. The proposed methodological strategy could report faecal contamination in water, mainly of human origin, and the condition of the matrix to maintain viral viability. In addition, the viral groups selected could report the presence of RV.

MicroRNA targeting of the non-canonical planar cell polarity pathway in the developing neural tube.

MicroRNAs (miRNAs) provide context-dependent transcriptional regulation of genes comprising signalling networks throughout the developing organism including morphogenesis of the embryonic neural tube (NT). Using a high-sensitivity, high-coverage microarray analysis platform, miRNA expression in the murine embryonic NT during the critical stages of its formation was examined. Analysis of a number of differentially expressed (DE) miRNAs enabled identification of several gene targets associated with cellular processes essential for normal NT development. Using computational pathway analysis, interactive biologic networks and functional relationships connecting DE miRNAs with their targeted messenger RNAs (mRNAs) were identified. Potential mRNA targets and a key signal transduction pathway governing critical cellular processes indispensable for normal mammalian neurulation were also identified. RNA preparations were also used to hybridize both miRNA arrays and mRNA arrays allowing miRNA-mRNA target analysis using data of DE miRNAs and DE mRNAs - co-expressed in the same developing NT tissue samples. Identification of these miRNA targets provides key insight into the epigenetic regulation of NT development as well as into potential mechanistic underpinning of NT defects. SIGNIFICANCE OF THE STUDY: This study underscores the premise that microRNAs are potential coordinators of normal neural tube (NT) formation, via regulation of the crucial, planar cell polarity pathway. Any alteration in their expression during neurulation would result in abnormal NT development.

Developmental toxicity of e-cigarette aerosols.

Maternal smoking during pregnancy represents a major public health concern increasing the risk for low birth weight, congenital anomalies, preterm birth, fetal mortality, and morbidity. In an effort to diminish adverse developmental effects of exposure to cigarette smoking, pregnant women, and women of reproductive age, are increasingly turning to electronic nicotine delivery systems (ENDS), such as e-cigarettes, as an alternative. Given that health risks associated with ENDS use during pregnancy are largely unknown, there is an acute need to determine risks vs. benefits of e-cigarette use by pregnant women. While the most recent Surgeon General's Report on the "Health Consequences of Smoking" states that "the evidence is sufficient to infer that nicotine adversely affects maternal and fetal health during pregnancy, contributing to multiple adverse outcomes," it remains unclear whether use of ENDS represents a "safer alternative" to tobacco smoking during pregnancy. This is due, in part, to the lack of sufficient and conclusive evidence concerning whether or not maternal e-cigarette use adversely affects embryonic/fetal development. While several recent developmental studies have challenged the safety of nicotine inhalation via ENDS, the true risks of smoking e-cigarettes during the first trimester of pregnancy-the period of organogenesis-are largely unknown. Moreover, evidence is emerging that even nicotine-free e-cigarette aerosols may harm the developing conceptus, suggesting that components of e-cigarette liquid, including flavorings, may be developmentally toxicity. Focused human epidemiological analyses, and carefully designed animal studies are critically needed to address the question of the safety of ENDS use during pregnancy.

Evaluation of Rapid Diagnostic Tests for Assessment of Hepatitis B in Resource-Limited Settings.

Chronic Hepatitis B (HBV) is the most important cause of liver disease worldwide. There is a need for low-cost tests to aid in diagnosis and management of HBV infection in resource-limited settings. We evaluated the utility of several rapid diagnostic tests (RDT) in three different continents (Europe, South America, Africa). The HBsAg RDT showed optimal sensitivity and specificity. The anti-HBeAb RDT showed acceptable sensitivity and excellent specificity. Our results suggest that these RDTs could be used for screening and management of HBV.

Impact of prenatal arsenate exposure on gene expression in a pure population of migratory cranial neural crest cells.

Prenatal exposure to arsenic, a naturally occurring toxic element, causes neural tube defects (NTDs) and, in animal models, orofacial anomalies. Since aberrant development or migration of cranial neural crest cells (CNCCs) can also cause similar anomalies within developing embryos, we examined the effects of in utero exposure to sodium arsenate on gene expression patterns in pure populations of CNCCs, isolated by fluorescence activated cell sorting (FACS), from Cre/LoxP reporter mice. Changes in gene expression were analyzed using Affymetrix GeneChip® microarrays and expression of selected genes was verified by TaqMan quantitative real-time PCR. We report, for the first time, arsenate-induced alterations in the expression of a number of novel candidate genes and canonical cascades that may contribute to the pathogenesis of orofacial defects. Ingenuity Pathway and NIH-DAVID analyses revealed cellular response pathways, biological themes, and potential upstream regulators, that may underlie altered fetal programming of arsenate exposed CNCCs.

Inflammation and ventricular-vascular coupling in hypertensive patients with metabolic syndrome.

BACKGROUND AND AIMS: Metabolic syndrome (MetS) is currently considered to raise the risk for type 2 diabetes and cardiovascular events. It has been suggested that part of this risk excess may be due to a cluster of additional factors associated with MetS. We aimed to investigate the role of inflammation on the ventricular-vascular coupling in patients with MetS. METHODS AND RESULTS: We enrolled a total of 227 hypertensive patients (106 with MetS and 121 without MetS) matched for age and gender. Aortic pulse wave velocity (aPWV), intima-media thickness (IMT) and high sensitivity C-reactive protein (CRP) increased according to the number of MetS components. Patients with MetS showed increased aPWV (11.5 ± 3.7 vs. 10.3 ± 2.5 m/s, P = 0.03) compared with controls. In a model adjusted for age, sex, heart rate and mean blood pressure, aPWV resulted increased in patients with CKD (beta 1.29 m/s, 95%CI 0.61-1.96 m/s, P < 0.001) and MetS (beta 0.89 m/s, 95%CI 0.28-1.51 m/s, P = 0.005). After additional adjustment for CRP and IMT, the slope of aPWV was respectively reduced by 16% and 62%, suggesting that inflammation and intima-media thickening could contribute to aortic stiffening in patients with MetS. In these patients, aPWV was also associated with left-ventricular mass index (beta 0.79 g/m2.7, 95%CI 0.05-1.52 g/m2.7, P = 0.05). CONCLUSION: MetS is characterized by an inflammation-dependent acceleration in cardiovascular ageing. This pattern of pathophysiological abnormalities may contribute to amplify the burden of cardiovascular risk in patients with MetS.

B-type natriuretic peptide may predict prognosis in older adults admitted with a diagnosis other than heart failure.

BACKGROUND AND AIMS: The diagnosis of heart failure (HF) in elderly patients is often difficult, due to overlap of typical signs and symptoms with those of comorbidities. B-type Natriuretic Peptide (BNP) predicts diagnosis and prognosis of HF, but little is known on its predictive role of short-term prognosis when admission diagnosis is other than HF. METHODS AND RESULTS: We prospectively recruited 404 consecutive patients (aged≥65 years) hospitalized in the Unit of Internal Medicine, University of Catania, Catania, Italy, with an admission diagnosis other than HF. Clinical examination, laboratory data and BNP were evaluated at the admission. The predictive value of BNP and other variables for in-hospital mortality, thirty-day mortality and three month re-hospitalization was assessed. During hospitalization 48 (12%) patients died; by logistic regression analysis, in-hospital mortality was not predicted by BNP>600 pg/ml (OR = 1.36; CI 95% = 0.60-2.80; p = 0.4), while it was by chronic kidney disease (CKD, p < 0.001), WBC count (p < 0.001), immobilization syndrome (p < 0.008) and age (p = 0.012). After discharge, 54 patients (15%) died within 30 days; in these patients thirty-day mortality was significantly predicted by BNP>600 pg/ml (OR = 2.70; CI 95% = 1.40-5.00; p = 0.001), CKD (p < 0.001), malnutrition (p = 0.029) and age (p = 0.033). Re-hospitalized patients were 97 (32%); three month re-hospitalization was predicted by BNP>600 pg/ml (OR = 12.28; CI 95% = 6.00-24.90; p < 0.001) and anamnestic HF (p = 0.002). CONCLUSIONS: Our study shows that BNP>600 pg/ml, CKD, malnutrition and age predict thirty-day mortality after discharge in elderly patients with an admission diagnosis other than HF, while CKD, WBC count, immobilization syndrome and age predict in-hospital mortality. Three-month re-hospitalization was predicted by BNP>600 pg/ml and anamnestic HF.

Effects of 5-Aza-2'-deoxycytidine (decitabine) on gene expression.

5-Aza-2'-deoxycytidine (AzaD), also known as Decitabine, is a deoxycytidine analog that is typically used to activate methylated and silenced genes by promoter demethylation. However, a survey of the scientific literature indicates that promoter demethylation may not be the only (or, indeed, the major) mechanism by which AzaD affects gene expression. Regulation of gene expression by AzaD can occur in several ways, including some that are independent of DNA demethylation. Results from several studies indicate that the effect of AzaD on gene expression is highly context-dependent and can differ for the same gene under different environmental settings. This may, in part, be due to the nature of the silencing mechanism(s) involved - DNA methylation, repressive histone modifications, or a combination of both. The varied effects of AzaD on such context-dependent regulation of gene expression may underlie some of the diverse responses exhibited by patients undergoing AzaD therapy. In this review, we describe the salient properties of AzaD with particular emphasis on its diverse effects on gene expression, aspects that have barely been discussed in most reviews of this interesting drug.

Enteric Viruses in Surface Waters from Argentina: Molecular and Viable-Virus Detection.

Water resources contaminated with wastewater are an important source for the dissemination of enteric viruses with an impact on the health of the population. The aim of the study was to assess the viral contamination of freshwater from a dam in Argentina by using infectious enterovirus detection, viral RNA amplification, and a genetic characterization of five enteric viruses associated with diarrhea and hepatitis. Enterovirus infectivity (iEV) was evaluated by cell culture and direct immunofluorescence. The detection of the viral genome of rotavirus (RV), human astrovirus (HAstV), norovirus (NoV), hepatitis A virus (HAV), and hepatitis E virus (HEV) was performed by reverse transcriptase PCR (RT-PCR). A total of 48 water samples from 4 monitoring points on the body of the dam from January to December 2012 and 66 water samples from 3 tourist beaches on the edge of the dam from October 2013 to October 2015 were collected monthly. During the first period, the overall viral frequency detection was 52.1% for group A RV, 50% for HAstV, 60.4% for NoV, 22.9% for HAV, 2.1% for HEV, and 64.6% for iEV. The overall frequency detection for the second sampling was 18.2% for RV and HAstV, 31.8% for NoV, 7.57% for HEV, and 66.7% for iEV. There was no detection of HAV during this period. The genotypes and genogroups detected through the study correlated with the most common genomic variants associated with human gastrointestinal and hepatitis illnesses. The results obtained could alert the health systems and environmental sanitation to make decisions for viral control and prevention in our environment.IMPORTANCE The study shows the impact of anthropic contamination of one of the most important tourist water resources in Argentina. This course of recreational water would be a favorable scenario for infection, as well as a reservoir for the enteric viruses, creating a risk for the population exposed to these waters. The results obtained could alert the health systems and environmental sanitation to make decisions for the control and prevention of viral diseases in this environment.

Determinants of orofacial clefting I: Effects of 5-Aza-2'-deoxycytidine on cellular processes and gene expression during development of the first branchial arch.

In this study, we identify gene targets and cellular events mediating the teratogenic action(s) of 5-Aza-2'-deoxycytidine (AzaD), an inhibitor of DNA methylation, on secondary palate development. Exposure of pregnant mice (on gestation day (GD) 9.5) to AzaD for 12h resulted in the complete penetrance of cleft palate (CP) in fetuses. Analysis of cells of the embryonic first branchial arch (1-BA), in fetuses exposed to AzaD, revealed: 1) significant alteration in expression of genes encoding several morphogenetic factors, cell cycle inhibitors and regulators of apoptosis; 2) a decrease in cell proliferation; and, 3) an increase in apoptosis. Pyrosequencing of selected genes, displaying pronounced differential expression in AzaD-exposed 1-BAs, failed to reveal significant alterations in CpG methylation levels in their putative promoters or gene bodies. CpG methylation analysis suggested that the effects of AzaD on gene expression were likely indirect.

Determinants of orofacial clefting II: Effects of 5-Aza-2'-deoxycytidine on gene methylation during development of the first branchial arch.

Defects in development of the secondary palate, which arise from the embryonic first branchial arch (1-BA), can cause cleft palate (CP). Administration of 5-Aza-2'-deoxycytidine (AzaD), a demethylating agent, to pregnant mice on gestational day 9.5 resulted in complete penetrance of CP in fetuses. Several genes critical for normal palatogenesis were found to be upregulated in 1-BA, 12h after AzaD exposure. MethylCap-Seq (MCS) analysis identified several differentially methylated regions (DMRs) in DNA extracted from AzaD-exposed 1-BAs. Hypomethylated DMRs did not correlate with the upregulation of genes in AzaD-exposed 1-BAs. However, most DMRs were associated with endogenous retroviral elements. Expression analyses suggested that interferon signaling was activated in AzaD-exposed 1-BAs. Our data, thus, suggest that a 12-h in utero AzaD exposure demethylates and activates endogenous retroviral elements in the 1-BA, thereby triggering an interferon-mediated response. This may result in the dysregulation of key signaling pathways during palatogenesis, causing CP.

Erratum to: 2016 WSES guidelines on acute calculous cholecystitis.

[This corrects the article DOI: 10.1186/s13017-016-0082-5.].