Ethanol-induced expression of ET-1 and ET-BR in liver sinusoidal endothelial cells and human endothelial cells involves hypoxia-inducible factor-1alpha and microrNA-199

Chronic alcohol drinking: Liver and pancreatic cancer?

Cancer is a multifactorial disease that results from complex interactions of numerous risk factors - genetic and environmental - over time, eventually leading to the diseased phenotypes. Thus, while epidemiological studies can point to risk factors, they cannot determine cause and effect relationships, and are unable to give biological and clinical insights into carcinogenesis. The link between any risk factor and carcinogenesis needs to be validated in experimental models. This is particularly true in epidemiological studies on alcohol consumption and its consequences. While there is no doubt that heavy alcohol consumption has devastating health effects, the inconsistencies in alcohol-related epidemiological studies and cancer suffer from possible sources of the variability in outcomes, ranging from inaccuracy of self-report of consumption to the problem of correlating cancer that started decades earlier to current or recent alcohol consumption. To further study the interactions between alcohol and cancer, the use of "Molecular Pathological Epidemiology" (MPE) advocated by Ogino et al. for dissecting the interplay between etiological factors, cellular and molecular characteristics, and disease progression in cancer is appropriate. MPE does not consider cancer as a single entity, rather it integrates analyses of epidemiological studies with the macroenvironment and molecular and microenvironment. This approach allows investigating the relationships between potential etiological agents and cancer based on molecular signatures. More research is needed to fully elucidate the link between heavy alcohol consumption and pancreatic cancer, and to further investigate the roles of acetaldehyde and FAEEs in pancreatic carcinogenesis.

Liver sinusoidal endothelial cells (LSECs) function and NAFLD; NO-based therapy targeted to the liver

Liver sinusoidal endothelial cells (LSECs) present unique, highly specialised endothelial cells in the body. Unlike the structure and function of typical, vascular endothelial cells, LSECs are comprised of fenestrations, display high endocytic capacity and play a prominent role in maintaining overall liver homeostasis. LSEC dysfunction has been regarded as a key event in multiple liver disorders; however, its role and diagnostic, prognostic and therapeutic significance in nonalcoholic fatty liver disease (NAFLD) is still neglected. The purpose of this review is to provide an overview of the importance of LSECs in NAFLD. Attention is focused on the LSECs-mediated NO-dependent mechanisms in NAFLD development. We briefly describe the unique, highly specialised phenotype of LSECs and consequences of LSEC dysfunction on function of hepatic stellate cells (HSC) and hepatocytes. The potential efficacy of liver selective NO donors against liver steatosis and novel treatment approaches to modulate LSECs-driven liver pathology including NAFLD are also highlighted.

MicroRNA responses to environmental liver carcinogens: Biological and clinical significance

A large number of biological, chemical, and dietary factors have been implicated in the development of liver cancer. These involve complex and protracted interactions between genetic, epigenetic, and environmental factors. The survival rate for patients diagnosed with late-stage liver cancer is currently low due to the aggressive nature of the disease and resistance to therapy. An increasing body of evidence has offered support for the crucial role of non-coding microRNA (miRNA) in directing hepatic responses to environmental risk factors for liver cancer. In this review we focus on miRNA responses to environmental liver cancer risk factors and their potential biological and clinical significance.

Phosphorylation dynamics of radixin in hypoxia-induced hepatocyte injury

The most prominent ezrin-radixin-moesin protein in hepatocytes is radixin, which is localized primarily at the canalicular microvilli and appears to be important in regulation of cell polarity and in localizing the multidrug resistance-associated protein 2 (Mrp-2) function. Our aim was to investigate how hypoxia affects radixin distribution and Mrp-2 function. We created wild-type and mutant constructs (in adenoviral vectors), which were expressed in WIF-B cells. The cellular distribution of Mrp-2 and radixin was visualized by fluorescence microscopy, and a 5-chloromethylfluorescein diacetate (CMFDA) assay was used to measure Mrp-2 function. Under usual conditions, cells infected with wild-type radixin, nonphosphorylatable radixin-T564A, and radixin-T564D (active phospho-mimicking mutant) were found to be heavily expressed in canalicular membrane compartment vacuoles, typically colocalizing with Mrp-2. In contrast, after hypoxia for 24 h, both endogenous and overexpressed wild-type radixin and the radixin-T564A mutant were found to be translocated to the cytoplasmic space. However, distribution of the radixin-T564D mutant, which mimics constant phosphorylation, was remarkably different, being associated with canalicular membranes even in hypoxic conditions. This dominant-active construct also prevented dissociation of radixin from the plasma membrane. Hypoxia also led to Mrp-2 mislocalization and caused Mrp-2 to be dissociated from radixin; the radixin phospho-mimicking mutant (T564D) abrogated this effect of hypoxia. Finally, hypoxia diminished the secretory response (measured using the CMFDA assay) in WIF-B cells, and the dominant-active construct (radixin-T567D) rescued this phenotype. Taken collectively, these findings suggest that radixin regulates Mrp-2 localization and function in hepatocytes and is important in hypoxic liver injury.

NADPH Oxidases in Chronic Liver Diseases

Oxidative stress is a common feature observed in a wide spectrum of chronic liver diseases including viral hepatitis, alcoholic, and nonalcoholic steatohepatitis. The nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs) are emerging as major sources of reactive oxygen species (ROS). Several major isoforms are expressed in the liver, including NOX1, NOX2, and NOX4. While the phagocytic NOX2 has been known to play an important role in Kupffer cell and neutrophil phagocytic activity and inflammation, the nonphagocytic NOX homologues are increasingly recognized as key enzymes in oxidative injury and wound healing. In this review, we will summarize the current advances in knowledge on the regulatory pathways of NOX activation, their cellular distribution, and their role in the modulation of redox signaling in liver diseases.

Emerging role of microRNAs in modulating endothelin-1 expression in gastric cancer

Endothelin-1 (ET-1) is a small 21-amino acid peptide that is known to exert diverse biological effects on a wide variety of tissues and cell types through its own receptors. The ET-1-ETRA axis is frequently dysfunctional in numerous types of carcinomas, and contributes to the promotion of cell growth and migration. microRNAs (miRNAs) are small non-coding RNAs that play a critical role in carcinogenesis through mRNA degradation or the translational inhibition of cancer-associated protein-coding genes. However, the role of ET-1 and the relationship between ET-1 and miRNAs in gastric cancer remain unknown. Results of the analysis of the database of The Cancer Genome Atlas (TCGA) revealed that ET-1 is significantly overexpressed in gastric cancer cells when compared with its expression in adjacent normal cells. Exogenous ET-1 significantly enhanced gastric cancer cell proliferation, implying that ET-1 plays an oncogenic role in gastric cancer carcinogenesis. Using a luciferase reporter assay we showed that 18 miRNA candidates had a significant silencing effect on ET-1 expression by up to 20% in HEK293T cells. Among them, 5 miRNAs (miR-1, miR-101, miR-125A, miR-144 and let-7c) were shown to be involved in ET-1 silencing through post-transcriptional modulation in gastric cancer. Our data also revealed that DNA hypermethylation contributes to the silenced miR-1 expression in gastric cancer cells. The ectopic expression of miR-1 significantly inhibited AGS cell proliferation by suppressing ET-1 expression. Overall, our study revealed that ET-1 overexpression may be due to DNA hypermethylation resulting in the silencing of miR-1 expression in gastric cancer cells. In addition, we identified several miRNAs as potential modulators for ET-1 in gastric cancer, which may be used as targets for gastric cancer therapy.

MicroRNAs: the fine modulators of liver development and function

MicroRNAs are a class of small non-coding RNAs involved in the transcriptional and post-transcriptional regulation of gene expression. The function of miRNAs in liver disease including hepatocellular carcinoma (HCC), hepatitis, and alcoholic liver disease, have been widely studied and extensively reviewed. Increasing evidence demonstrates that miRNAs also play a critical role in normal liver development and in the fine-tuning of fundamental biological liver processes. In this review, we highlight the most recent findings on the role of miRNAs in liver specification and differentiation, liver cell development, as well as in the many metabolic functions of the liver, including glucose, lipid, iron and drug metabolism. These findings demonstrate an important role of miRNAs in normal liver development and function. Further researches will be needed to fully understand how miRNAs regulate liver generation and metabolic function, which should then lead to greater insights in liver biology and perhaps open up the possibility to correct errors that cause liver diseases or metabolic disorders.

Endothelial progenitor cells and a stromal cell-derived factor-1α analogue synergistically improve survival in sepsis

RATIONALE

Endothelial progenitor cells (EPCs) have been associated with human sepsis but their role is incompletely understood. Stromal cell-derived factor (SDF)-1α facilitates EPC recruitment and is elevated in murine sepsis models. Previous studies have demonstrated that the SDF-1α analog CTCE-0214 (CTCE) is beneficial in polymicrobial sepsis induced by cecal ligation and puncture (CLP) in mice.

OBJECTIVES

We hypothesized that exogenously administered EPCs are also beneficial in CLP sepsis and that CTCE provides synergistic benefit.

METHODS

Mice were subjected to CLP and administered EPCs at varying doses, CTCE, or a combination of the two. Mouse survival, plasma miRNA expression, IL-10 production, and lung vascular leakage were determined. The in vitro effect of CTCE on miRNA expression and EPC function were determined.

MEASUREMENTS AND MAIN RESULTS

Survival was improved with EPC therapy at a threshold of 10(6) cells. In coculture studies, EPCs augmented LPS-induced macrophage IL-10 production. In vivo EPC administration in sepsis increased plasma IL-10, suppressed lung vascular leakage, attenuated liver and kidney injury, and augmented miR-126 and -125b expression, which regulate endothelial cell function and/or inflammation. When subthreshold numbers of EPCs were coadministered with CTCE in CLP mice they synergistically improved survival. We demonstrated that CTCE recruits endogenous EPCs in septic mice. In in vitro analysis, CTCE enhanced EPC proliferation, angiogenesis, and prosurvival signaling while inhibiting EPC senescence. These cellular effects were, in part, explained by the effect of CTCE on miR-126, -125b, -34a, and -155 expression in EPCs.

CONCLUSIONS

EPCs and CTCE represent important potential therapeutic strategies in sepsis.

Maternal alcohol consumption in pregnancy enhances arterial stiffness and alters vasodilator function that varies between vascular beds in fetal sheep

While the impact of alcohol consumption by pregnant women on fetal neurodevelopment has received much attention, the effects on the cardiovascular system are not well understood. We hypothesised that repeated exposure to alcohol (ethanol) in utero would alter fetal arterial reactivity and wall stiffness, key mechanisms leading to cardiovascular disease in adulthood. Ethanol (0.75 g (kg body weight)(-1)) was infused intravenously into ewes over 1 h daily for 39 days in late pregnancy (days 95-133 of pregnancy, term ∼147 days). Maternal and fetal plasma ethanol concentrations at the end of the hour were ∼115 mg dl(-1), and then declined to apparent zero over 8 h. At necropsy (day 134), fetal body weight and fetal brain-body weight ratio were not affected by alcohol infusion. Small arteries (250-300 μm outside diameter) from coronary, renal, mesenteric, femoral (psoas) and cerebral beds were isolated. Endothelium-dependent vasodilatation sensitivity was reduced 10-fold in coronary resistance arteries, associated with a reduction in endothelial nitric oxide synthase mRNA (P = 0.008). Conversely, vasodilatation sensitivity was enhanced 10-fold in mesenteric and renal resistance arteries. Arterial stiffness was markedly increased (P = 0.0001) in all five vascular beds associated with an increase in elastic modulus and, in cerebral vessels, with an increase in collagen Iα mRNA. Thus, we show for the first time that fetal arteries undergo marked and regionally variable adaptations as a consequence of repeated alcohol exposure. These alcohol-induced vascular effects occurred in the apparent absence of fetal physical abnormalities or fetal growth restriction.

The up-regulation of endothelin-1 and down-regulation of miRNA-125a-5p, -155, and -199a/b-3p in human atherosclerotic coronary artery

BACKGROUND

Previous studies have reported important roles of endothelin-1 (ET-1) and angiotensin II (Ang II) in the pathogenesis of atherosclerosis. However, the expression of these two proteins and the underlying mechanisms in human atherosclerotic coronary arteries are largely unknown.

METHODS

We examined the expression of ET-1 and Ang II in pericardial fluid and coronary arteries from 25 individuals (n = 25) using enzyme-linked immuno sorbent assay (ELISA) and immunohistochemistry. Twelve patients died from acute coronary syndrome were classified as atherosclerotic plaque group (AP group) (n = 12), while 13 patients died from other causes were classified as non-AP group (n = 13). Meanwhile, we performed reverse transcription-polymerase chain reaction (RT-PCR) to measure the expression of six microRNAs targeting ET-1 in formalin-fixed, paraffin-embedded coronary arteries.

RESULTS

Our data showed that ET-1 was significantly higher in both pericardial fluid and coronary arteries from AP group. However, Ang II showed no significant difference in pericardial fluid between the two groups, while it was even significantly lower in coronary arteries from AP group. Besides, miR-125a-5p, miR-155, and miR-199a/b-3p, which suppressed the expression of ET-1, were down-regulated in the coronary arteries from AP group.

CONCLUSION

The up-regulation of ET-1, regulated by miR-125a-5p, miR-155, and miR-199a/b-3p, indicated that ET-1 played an important role in human coronary atherosclerosis.

SUMMARY

We focused on the human coronary arteries with atherosclerotic plaques. The expression of ET-1, as well as its upstream miRNAs, was determined. Unlike any of previous study regarding miRNAs expression, we could exclude the discrepancy of artery-bed-specific miRNA expression. Besides, our data indicated, to some degree, that ET-1 might play a more vital role than Ang II in coronary atherosclerosis.

MicroRNA regulation of endothelin-1 mRNA in renal collecting duct cells

AIMS

Recently, microRNAs (miRNAs) have been implicated in control of Edn1 mRNA in several tissues. Here we examined the role of miRNA action on Edn1 mRNA expression in renal distal collecting duct cells.

MAIN METHODS

A microarray study was conducted to provide a comprehensive assessment of miRNAs present in a murine inner medullary collecting duct (mIMCD-3) cell line. The experiment was designed as a comparison between mIMCD-3 cells grown in the presence and absence of aldosterone. Argonaute (Ago) immunoprecipitation experiments were used to investigate binding of the RNA induced silencing complex (RISC) to Edn1 mRNA.

KEY FINDINGS

Thirty-four miRNAs were detected in very high abundance in mIMCD-3 cells, and a large number of others were present at lower levels. The microarray experiments were validated by quantitative PCR analysis of selected miRNAs. The microarray data, in combination with in silico examination of the Edn1 3' UTR provided a panel of candidate miRNAs that could act upon the Edn1 expression. Edn1 mRNA was co-immunoprecipitated with an Argonaute protein antibody, and this interaction was blocked by anti-miR-709 oligonucleotides.

SIGNIFICANCE

These results define the miRNA landscape of the mIMCD-3 cell line. Moreover, Edn1 was shown to interact with Argonaute protein suggesting that it is a target of the RNA induced silencing complex (RISC).

Toxic damage increases angiogenesis and metastasis in fibrotic livers via PECAM-1

Excessive ethanol consumption is one of the main causes of liver fibrosis. However, direct effects of ethanol exposure on endothelial cells and their contribution to fibrogenesis and metastasis were not investigated. Therefore we analysed whether ethanol directly affects endothelial cells and if this plays a role during fibrogenesis and metastasis in the liver. Murine and human endothelial cells were exposed to ethanol for up to 72 hours. In vitro, effects on VEGF, HIF-1alpha, PECAM-1, and endothelial cell functions were analysed. In vivo, effects of continuous liver damage on blood vessel formation and metastasis were analysed by PECAM-1 immunohistochemistry. Ethanol increased HIF-1alpha and VEGF levels in murine and human endothelial cells. This resulted in enhanced intracellular signal transduction, and PECAM-1 expression as well as tube formation and wound healing. In vivo, toxic liver damage increased angiogenesis during fibrogenesis. Metastasis was also enhanced in fibrotic livers and located to PECAM-1 positive blood vessels compared to nonfibrotic mice. In conclusion, ethanol had strong effects on endothelial cells, which—at least in part—led to a profibrotic and prometastatic environment mediated by PECAM-1. Blockade of increased PECAM-1 expression could be a promising tool to inhibit fibrogenesis and metastasis in the liver.

The functional role of microRNAs in alcoholic liver injury

The function of microRNAs (miRNAs) during alcoholic liver disease (ALD) has recently become of great interest in biological research. Studies have shown that ALD associated miRNAs play a crucial role in the regulation of liver-inflammatory agents such as tumour necrosis factor-alpha (TNF-α), one of the key inflammatory agents responsible for liver fibrosis (liver scarring) and the critical contributor of alcoholic liver disease. Lipopolysaccharide (LPS), a component of the cell wall of gram-negative bacteria, is responsible for TNF-α release by Kupffer cells. miRNAs are the critical mediators of LPS signalling in Kupffer cells, hepatocytes and hepatic stellate cells. Certain miRNAs, in particular miR-155 and miR-21, show a positive correlation in up-regulation of LPS signalling when they are exposed to ethanol. ALD is related to enhanced gut permeability that allows the levels of LPS to increase, leads to increased secretion of TNF-α by the Kupffer cells and subsequently promotes alcoholic liver injury through specific miRNAs. Meanwhile, two of the most frequently dysregulated miRNAs in steatohepatitis, miR-122 and miR-34a are the critical mediators in ethanol/LPS activated survival signalling during ALD. In this review, we summarize recent findings regarding the experimental and clinical aspects of functions of specific microRNAs, focusing mainly on inflammation and cell survival after ethanol/LPS treatment, and advances on the role of circulating miRNAs in human alcoholic disorders.

The profibrotic role of endothelin-1: is the door still open for the treatment of fibrotic diseases?

The endothelin (ET) system consists of two G-protein-coupled receptors (ETA and ETB), three peptide ligands (ET-1, ET-2 and ET-3), and two activating peptidases (endothelin-converting enzyme-, ECE-1 and ECE-2). While initially described as a vasoregulatory factor, shown to influence several cardiovascular diseases, from hypertension to heart failure, ET-1, the predominant form in most cells and tissues, has expanded its pathophysiological relevance by recent evidences implicating this factor in the regulation of fibrosis. In this article, we review the current knowledge of the role of ET-1 in the development of fibrosis, with particular focus on the regulation of its biosynthesis and the molecular mechanisms involved in its profibrotic actions. We summarize also the contribution of ET-1 to fibrotic disorders in several organs and tissues. The development and availability of specific ET receptor antagonists have greatly stimulated a number of clinical trials in these pathologies that unfortunately have so far given negative or inconclusive results. This review finally discusses the circumstances underlying these disappointing results, as well as provides basic and clinical researchers with arguments to keep exploring the complex physiology of ET-1 and its therapeutic potential in the process of fibrosis.

MicroRNAs in liver disease

Small, noncoding microRNAs (miRNAs) regulate diverse biological functions in the liver and increasing evidence suggests that they have a role in liver pathology. This Review summarizes advances in the field of miRNAs in liver diseases, inflammation and cirrhosis. MicroRNA-122, the most abundant miRNA in hepatocytes, has well-defined roles in HCV replication, and data indicate that it also serves as a viable therapeutic target. The role of miR-122 is also emerging in other liver diseases. Ample evidence exists for the important regulatory potential of other miRNAs in conditions associated with liver inflammation related to alcohol use, the metabolic syndrome or autoimmune processes. In addition, a broad array of miRNAs have been associated with the development of liver fibrosis both in animal models and human studies. The significance of the function and cellular distribution of miRNAs in the liver and the potential of miRNAs as a means of communication between cells and organs is discussed as well as the emerging utility of circulating miRNAs as biomarkers of different forms of liver damage and as early markers of disease and progression in hepatocellular carcinoma. Importantly, miRNA modulation in the liver represents a new therapeutic approach in the treatment armamentarium of hepatologists in the future.

MicroRNAs in Liver Disease: Bench to Bedside

MicroRNAs (miRs) are small non-coding RNAs that negatively regulate gene expression by pairing with partially complementary target sequences in the 3'UTRs of mRNAs to promote degradation and/or block translation. Aberrant miR expression is associated with development of multiple diseases including hepatic diseases. The role of miRs in the regulation of gene expression and rapid progress in the field of microRNA research are resulting in momentum toward development of diagnostic markers and novel therapeutic strategies for human liver diseases. Recent studies provide clear evidence that miRs are abundant in the liver and modulate a diverse spectrum of biological functions, thereby supporting an association between alterations of miR homeostasis and pathological liver diseases. Here we review the role of miRs in liver as their physiological and pathological importance has been demonstrated in metabolism, immunity, viral hepatitis, oncogenesis, fatty liver diseases (alcoholic and non-alcoholic), drug-induced liver injury, fibrosis as well as acute liver failure.

MiR-214 promotes the alcohol-induced oxidative stress via down-regulation of glutathione reductase and cytochrome P450 oxidoreductase in liver cells

BACKGROUND

The involvement of oxidative stress in the pathophysiological process of alcohol-induced liver injury has been studied for decades. However, the role of microRNAs (miRNAs) targeting to oxidative stress genes in the pathogenesis of alcohol-induced liver injury has not yet been determined. The aim of this study was to identify the targeting of miR-214 to both glutathione reductase (GSR) and cytochrome P450 oxidoreductase (POR) genes and elucidate their impact on alcohol-induced oxidative stress in liver cells.

METHODS

The miR-214 expression vector and reporter vectors of GSR and POR 3'-UTR were constructed. Human hepatoma cell (Bel7402), human embryonic kidney 293 cell (HEK293), and rat normal hepatocyte (BRL) were transfected and stimulated with ethanol (EtOH). Wistar rats were fed with EtOH for 4 weeks. The GSR and POR protein levels were detected by Western blot, and their activities were measured using the spectrophotometric method. The miR-214 expression was detected by real-time PCR. The index of oxidative stress including the total antioxidant capacity (T-AOC) and malondialdehyde (MDA) level was detected by commercial kits.

RESULTS

miR-214 bound specifically to the GSR and POR 3'-UTR and repressed the expressions and activities of both GSR and POR. EtOH up-regulated the miR-214 expression, down-regulated the GSR and POR protein levels and activities, and induced the oxidative stress in human and rat liver cells. EtOH-fed Wistar rats further confirmed that alcohol up-regulates the miR-214 expression in liver and repressed both GSR and POR in vivo.

CONCLUSIONS

These findings demonstrated a new mechanism by which the alcohol repressed the GSR and POR expression via up-regulation of miR-214 and in turn induced oxidative stress in liver cells.

An emerging role for microRNA in the regulation of endothelin-1

Endothelin-1 (ET-1) is a peptide signaling molecule serving diverse functions in many different tissues such as the vasculature and the kidney. The primary mechanism thought to control ET-1 bioavailability is the rate of transcription from the ET-1 gene (EDN1), but recent research suggests that EDN1 expression is attenuated by microRNA (miRNA)—mediated regulation. The action of specific miRNAs on EDN1 mRNA appears to vary greatly in a tissue specific manner. This review provides a summary of our current understanding of miRNA-EDN1 interaction.

Epigenetics of hypoxic pulmonary arterial hypertension following intrauterine growth retardation rat: epigenetics in PAH following IUGR

Background

Accumulating evidence reveals that intrauterine growth retardation (IUGR) can cause varying degrees of pulmonary arterial hypertension (PAH) later in life. Moreover, epigenetics plays an important role in the fetal origin of adult disease. The goal of this study was to investigate the role of epigenetics in the development of PAH following IUGR.

Methods

The IUGR rats were established by maternal undernutrition during pregnancy. Pulmonary vascular endothelial cells (PVEC) were isolated from the rat lungs by magnetic-activated cell sorting (MACS). We investigated epigenetic regulation of the endothelin-1 (ET-1) gene in PVEC of 1-day and 6-week IUGR rats, and response of IUGR rats to hypoxia.

Results

The maternal nutrient restriction increased the histone acetylation and hypoxia inducible factor-1α (HIF-1α) binding levels in the ET-1 gene promoter of PVEC in IUGR newborn rats, and continued up to 6 weeks after birth. These epigenetic changes could result in an IUGR rat being highly sensitive to hypoxia later in life, causing more significant PAH or pulmonary vascular remodeling.

Conclusions

These findings suggest that epigenetics is closely associated with the development of hypoxic PAH following IUGR, further providing a new insight for improved prevention and treatment of IUGR-related PAH.

Ethanol alters alveolar fluid balance via Nadph oxidase (NOX) signaling to epithelial sodium channels (ENaC) in the lung

Chronic alcohol consumption is associated with increased incidence of ICU-related morbidity and mortality, primarily from acute respiratory distress syndrome (ARDS). However, the mechanisms involved are unknown. One explanation is that alcohol regulates epithelial sodium channels (ENaC) via oxidant signaling to promote a pro- injury environment. We used small rodent models to mimic acute and chronic alcohol consumption and tested the hypothesis that ethanol (EtOH) would affect lung fluid clearance by up-regulating ENaC activity in the lung. Fluorescence labeling of rat lung slices and in vivo mouse lung revealed an increase in ROS production in response to acute EtOH exposure. Using western blots and fluorescein-5-maleimide labeling, we conclude that EtOH exposure modifies cysteines of α-ENaC while data from single channel patch clamp analysis confirm that 0.16% EtOH increased ENaC activity in rat alveolar cells. In vivo lung fluid clearance demonstrated a latent increase in fluid clearance in mice receiving EtOH diet. Ethanol mice given a tracheal instillation of LPS demonstrated early lung fluid clearance compared to caloric control mice and C57Bl/6 mice. Standard biochemical techniques reveal that chronic EtOH consumption resulted in greater protein expression of the catalytic gp91^phox subunit and the obligate Rac1 protein. Collectively these data suggest that chronic EtOH consumption may lead to altered regulation of ENaC, contributing to a ‘pro-injury’ environment in the alcohol lung.

Endothelin-2, the forgotten isoform: emerging role in the cardiovascular system, ovarian development, immunology and cancer

Endothelin-2 [ET-2; also known as vasoactive intestinal contractor (VIC), in rodents] differs from endothelin-1 (ET-1) by only two amino acids, and unlike the third isoform, endothelin-3 (ET-3), it has the same affinity as ET-1 for both ET(A) and ET(B) receptors. It is often assumed that ET-2 would mimic the actions of the more abundant ET-1 and current pharmacological interventions used to inhibit the ET system would also block the actions of ET-2. These assumptions have focused research on ET-1 with ET-2 studied in much less detail. Recent research suggests that our understanding of the ET family requires re-evaluation. Although ET-2 is very similar in structure as well as pharmacology to ET-1, and may co-exist in the same tissue compartments, there is converging evidence for an important and distinct ET-2 pathway. Specifically is has been demonstrated that ET-2 has a key role in ovarian physiology, with ET-2-mediated contraction proposed as a final signal facilitating ovulation. Furthermore, ET-2 may also have a pathophysiological role in heart failure, immunology and cancer. Comparison of ET-2 versus ET-1 mRNA expression suggests this may be accomplished at the level of gene expression but differences may also exist in peptide synthesis by enzymes such as endothelin converting enzymes (ECEs) and chymase, which may allow the two pathways to be distinguished pharmacologically and become separate drug targets. LINKED ARTICLES This article is part of a themed section on Endothelin. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.168.issue-1.

Epigenetic effects of ethanol on the liver and gastrointestinal system

The widening web of epigenetic regulatory mechanisms also encompasses ethanol-induced changes in the gastrointestinal (GI)-hepatic system. In the past few years, increasing evidence has firmly established that alcohol modifies several epigenetic parameters in the GI tract and liver. The major pathways affected include DNA methylation, different site-specific modifications in histone proteins, and microRNAs. Ethanol metabolism, cell-signaling cascades, and oxidative stress have been implicated in these responses. Furthermore, ethanol-induced fatty liver (i.e., steatohepatitis) and progression of liver cancer (i.e., hepatic carcinoma) may be consequences of the altered epigenetics. Modification of gene and/or protein expression via epigenetic changes also may contribute to the cross-talk among the GI tract and the liver as well as to systemic changes involving other organs. Thus, epigenetic effects of ethanol may have a central role in the various pathophysiological responses induced by ethanol in multiple organs and mediated via the liver-GI axis.

OxymiRs in cutaneous development, wound repair and regeneration

The state of tissue oxygenation is widely recognized as a major microenvironmental cue that is known to regulate the expression of coding genes. Recent works have extended that knowledge to demonstrate that the state of tissue oxygenation may potently regulate the expression of microRNAs (miRs). Collectively, such miRs that are implicated in defining biological outcomes in response to a change in the state of tissue oxygenation may be referred to as oxymiRs. Broadly, oxymiRs may be categorized into three groups: (A) the existence (expression and/or turnover) of which is directly influenced by changes in the state of tissue oxygenation; (B) the existence of which is indirectly (e.g. oxygen-sensitive proteins, metabolites, pH, etc.) influenced by changes in the state of tissue oxygenation; and (C) those that modify biological outcomes to changes in the state of tissue oxygenation by targeting oxygen sensing pathways. This work represents the first review of how oxymiRs may regulate development, repair and regeneration. Currently known oxymiRs may affect the functioning of a large number of coding genes which have hitherto fore never been linked to oxygen sensing. Many of such target genes have been validated and that number is steadily growing. Taken together, our understanding of oxymiRs has vastly expanded the implications of changes in the state of tissue oxygenation. This emerging paradigm has major implications in untangling the complexities underlying diseases associated with ischemia and related hypoxic insult such as chronic wounds.

Association of adrenomedullin gene polymorphisms and blood pressure in a Chinese population

Genetic factors may determine an individual's blood pressure (BP) level and risk for hypertension. This study aimed to examine the associations between genetic variants of the adrenomedullin (ADM) gene and essential hypertension, as well as BP levels, in a Chinese Han population. In this study, 2410 hypertensive patients and 2346 normal controls were recruited. Three tagging single-nucleotide polymorphisms (SNPs) based on the HapMap CHB data were selected and genotyped. No significant associations between the three SNPs of the ADM gene and hypertension status were observed. However, SNP rs4399321 was found to be associated with BP levels among the controls. GG homozygotes for this SNP had higher systolic BP (SBP) levels than carriers of the A allele (P=0.002). Particularly in non-drinkers, GG homozygotes had significantly higher SBP (116.9±0.9 vs. 113.7±0.3 mm Hg, P=0.001) and diastolic (74.0±0.7 vs. 72.6±0.2 mm Hg, P=0.046) BP levels than carriers of the A allele. Neither rs4910118 nor rs7944706 was associated with BP levels in the controls either before or after being stratified by drinking status. The results of this study showed that genetic variations in the ADM gene were not associated with the risk of hypertension in a Chinese population. However, the genotype at common variation rs4399321 may influence the BP level in normotensive subjects, especially among non-drinkers. In addition, replications in other populations and further functional studies are required to confirm and interpret the association of ADM with BP.

MicroRNA-1 inhibits proliferation of hepatocarcinoma cells by targeting endothelin-1

AIMS

MicroRNA-1 (miR-1) has been demonstrated as a tumor-suppressive miRNA, which shows a down-regulated pattern in several human malignancies including hepatocellular carcinoma (HCC). However, the pathophysiologic roles of miR-1 and their mechanisms in HCC tumorigenesis are still not totally elucidated.

MAIN METHODS

Pre-miR-1 was cloned into pSuper plasmid to overexpress the miR-1 in hepatoma cells. Real-time PCR and Western blot were applied to detect miR-1, ET-1 mRNA and protein levels respectively. Dual luciferase reporter assay was conducted to investigate the binding site of miR-1 on 3'UTR of ET-1 mRNA. Proliferation of hepatoma cells was evaluated by MTT assay.

KEY FINDINGS

We observed that over-expression of miR-1 by miRNA-expressing plasmid transfection in HepG2 and Hep3B cells significantly reduced the proliferation of these cells. To explore the mechanism, we examined the potential target genes of miR-1 by bioinformatics. A potent mitogen, Endothelin-1 (ET-1), attracted our attention. Elevated expression of ET-1 but reduced miR-1 level was detected both in human liver cancer tissues and in hepatoma cell lines using Western Blot and miRNA real-time PCR respectively. By the over-expression and inhibition of miR-1 in HepG2 and Hep3B, we confirmed that miR-1 negatively regulated ET-1 expression in hepatoma cells. A luciferase reporter assay showed that miR-1 regulation was established by pairing to a complementary binding site within the ET-1 3'UTR. Finally, attenuated proliferation of hepatoma cells by over-expression of miR-1 could be partially restored by exogenous ET-1 treatment.

SIGNIFICANCE

Our findings demonstrate that miR-1 could inhibit ET-1 expression to attenuate the proliferation of hepatoma cells.

The endothelin axis in uterine leiomyomas: new insights

The endothelin axis, comprising endothelin-1 (ET-1) and its receptors (ETA and ETB), is involved in the pathophysiology of different human tumors. Here we review conventional approaches and gene expression profiling indicating the association of ET-1 and its cognate receptors with human and rat leiomyomas, the most common benign tumors of myometrium. Specifically, ET-1/ETA interactions affect human and rat leiomyoma cell proliferation through protein kinase C and mitogen-activated protein kinase-dependent signaling pathways. Recent experiments demonstrate that the ET-1 axis exerts a potent antiapoptotic effect involving sphingolipid metabolism and prostaglandin-endoperoxide synthase 2/prostaglandin system in the rat Eker leiomyoma tumor-derived ELT3 cell line. Evidence supports that steroid hormones, growth factors, and extracellular matrix are key regulators of the leiomyoma growth. Interestingly, the ET-1 axis is under steroid hormones and can cooperate with these growth factors. Therefore, ET-1 alone or in association with these factors could contribute to the complex regulation of uterine tumor growth, such as proliferation, survival, and extracellular matrix production. This review summarizes current knowledge and emerging data on ET-1 in uterine leiomyoma pathology.

MicroRNAs: Small but amazing, and their association with endothelin

MicroRNAs (miRNAs) are small non-coding RNA molecules involved in the expressional regulation of genes by inhibiting gene translation. MicroRNAs are recruited and incorporated into the miRISC, ribonucleoprotein complex, targeting specific mRNAs through mechanisms specific for a miRNA sequence. Here we review the biogenesis, regulation, and monitoring of miRNAs, as well as the current evidence for potential roles of miRNAs in human diseases associated with activation of the endothelin system. These diseases include cancer, kidney disease, cardiovascular diseases, inflammatory diseases, infectious diseases, and blood diseases, that may all be aggravated by aberrant miRNA expression. In this review we will also discuss regulatory mechanisms determining production of miRNA as well as measuring or targeting miRNAs as potential novel approaches for diagnosis and treatment. Targeting miRNAs possibly will allow one to detect diseases or to interfere with the progression of diseases associated with activation of the endothelin system.

Environmental exposures, epigenetics and cardiovascular disease

PURPOSE OF REVIEW

Epigenetic modifications are heritable alterations of the genome, which can govern gene expression without altering the DNA sequence. The purpose of this review is to render an overview of the possible mechanisms of epigenetic regulation of gene expression in response to environmental pollutants leading to cardiovascular diseases (CVD).

RECENT FINDINGS

An era of cataloging epigenetic marks of the various diseased states has recently commenced, including those within the genes responsible for atherosclerosis, ischemia, hypertension and heart failure. From varied study approaches directed either toward the general understanding of the key pathway regulatory genes, or sampling population cohorts for global and gene-specific changes, it has been possible to identify several epigenetic signatures of environmental exposure relevant to CVD. Signatures of epigenetic dysregulation can be detected in peripheral blood samples, even within a few hours of environmental exposure. However, the field now faces the demand for thorough, systematic, rationalized approaches to establish the relation of exposure-driven epigenetic changes to clinical outcomes, by using sophisticated and reliable research designs and tools.

SUMMARY

An understanding of chromatin remodelling in response to environmental stimuli conducive to CVD is emerging, with the promise of novel diagnostic and therapeutic candidates.

MicroRNAs in liver disease

MicroRNAs are small noncoding RNA molecules that regulate gene expression posttranscriptionally through complementary base pairing with thousands of messenger RNAs. They regulate diverse physiological, developmental, and pathophysiological processes. Recent studies have uncovered the contribution of microRNAs to the pathogenesis of many human diseases, including liver diseases. Moreover, microRNAs have been identified as biomarkers that can often be detected in the systemic circulation. We review the role of microRNAs in liver physiology and pathophysiology, focusing on viral hepatitis, liver fibrosis, and cancer. We also discuss microRNAs as diagnostic and prognostic markers and microRNA-based therapeutic approaches for liver disease.

Endothelin-1 activation of ETB receptors leads to a reduced cellular proliferative rate and an increased cellular footprint

Endothelin-1 (ET-1) is a vasoactive peptide which signals through two G-protein coupled receptors, endothelin receptor A (ETA) and B (ETB). We determined that ET-1 activation of its ETB receptor in stably cDNA transfected CHO cells leads to a 55% reduction in cell number by end-point cell counting and a 35% decrease in cell growth by a real-time cell-substrate impedance-based assay after 24h of cell growth. When CHO ETB cells were synchronized in the late G1 cell cycle phase, ET-1 delayed their S phase progression compared to control by 30% as determined by [(3)H]-thymidine incorporation. On the other hand, no such delay was observed during late G2/M to G1 transit when cells were treated with ET-1 after release from mitotic arrest. Using the cell-substrate impedance-based assay, we observed that ET-1 induces opposing morphological changes in CHO ETA and CHO ETB cells with ETB causing an increase in the cell footprint and ETA a decrease. Likewise, in pulmonary artery smooth muscle cells, which express both ETA and ETB receptors, ET-1 induces an ETA-dependent contraction and an ETB dependent dilation. These results are shedding light on a possible beneficial role for ETB in diseases involving ET-1 dysfunction such as pulmonary hypertension.

Adenosine triphosphate-binding cassette transporter genes up-regulation in untreated hepatocellular carcinoma is mediated by cellular microRNAs

Adenosine triphosphate (ATP)-binding cassette (ABC) transporters are drug efflux pumps responsible for the multidrug resistance phenotype causing hepatocellular carcinoma (HCC) treatment failure. Here we studied the expression of 15 ABC transporters relevant for multidrug resistance in 19 paired HCC patient samples (16 untreated, 3 treated by chemotherapeutics). Twelve ABC transporters showed up-regulation in HCC compared with adjacent healthy liver. These include ABCA2, ABCB1, ABCB6, ABCC1, ABCC2, ABCC3, ABCC4, ABCC5, ABCC10, ABCC11, ABCC12, and ABCE1. The expression profile and function of some of these transporters have not been associated with HCC thus far. Because cellular microRNAs (miRNAs) are involved in posttranscriptional gene silencing, we hypothesized that regulation of ABC expression in HCC might be mediated by miRNAs. To study this, miRNAs were profiled and dysregulation of 90 miRNAs was shown in HCC compared with healthy liver, including up-regulation of 11 and down-regulation of 79. miRNA target sites in ABC genes were bioinformatically predicted and experimentally verified in vitro using luciferase reporter assays. In total, 13 cellular miRNAs were confirmed that target ABCA1, ABCC1, ABCC5, ABCC10, and ABCE1 genes and mediate changes in gene expression. Correlation analysis between ABC and miRNA expression in individual patients revealed an inverse relationship, providing an indication for miRNA regulation of ABC genes in HCC.

CONCLUSION

Up-regulation of ABC transporters in HCC occurs prior to chemotherapeutic treatment and is associated with miRNA down-regulation. Up-regulation of five ABC genes appears to be mediated by 13 cellular miRNAs in HCC patient samples. miRNA-based gene therapy may be a novel and promising way to affect the ABC profile and overcome clinical multidrug resistance.

MicroRNA-217 promotes ethanol-induced fat accumulation in hepatocytes by down-regulating SIRT1

Ethanol-mediated inhibition of hepatic sirtuin 1 (SIRT1) plays a crucial role in the pathogenesis of alcoholic fatty liver disease. Here, we investigated the underlying mechanisms of this inhibition by identifying a new hepatic target of ethanol action, microRNA-217 (miR-217). The role of miR-217 in the regulation of the effects of ethanol was investigated in cultured mouse AML-12 hepatocytes and in the livers of chronically ethanol-fed mice. In AML-12 hepatocytes and in mouse livers, chronic ethanol exposure drastically and specifically induced miR-217 levels and caused excess fat accumulation. Further studies revealed that overexpression of miR-217 in AML-12 cells promoted ethanol-mediated impairments of SIRT1 and SIRT1-regulated genes encoding lipogenic or fatty acid oxidation enzymes. More importantly, miR-217 impairs functions of lipin-1, a vital lipid regulator, in hepatocytes. Taken together, our novel findings suggest that miR-217 is a specific target of ethanol action in the liver and may present as a potential therapeutic target for treating human alcoholic fatty liver disease.

Endothelial dysfunction in the regulation of cirrhosis and portal hypertension

Portal hypertension is caused by an increased intrahepatic resistance, a major consequence of cirrhosis. Endothelial dysfunction in liver sinusoidal endothelial cells (LSECs) decreases the production of vasodilators, such as nitric oxide, and favours vasoconstriction. This contributes to an increased vascular resistance in the intrahepatic/sinusoidal microcirculation and develops portal hypertension. Portal hypertension, in turn, causes endothelial dysfunction in the extrahepatic, i.e. splanchnic and systemic, circulation. Unlike dysfunction in LSECs, endothelial dysfunction in the splanchnic and systemic circulation causes overproduction of vasodilator molecules, leading to arterial vasodilation. In addition, portal hypertension leads to the formation of portosystemic collateral vessels. Both arterial vasodilation and portosystemic collateral vessel formation exacerbate portal hypertension by increasing the blood flow through the portal vein. Pathological consequences, such as oesophageal varices and ascites, result. While the sequence of pathological vascular events in cirrhosis and portal hypertension has been elucidated, the underlying cellular and molecular mechanisms causing endothelial dysfunctions are not yet fully understood. This review article summarizes the current cellular and molecular studies on endothelial dysfunctions found during the development of cirrhosis and portal hypertension with a focus on the intra- and extrahepatic circulations. The article ends by discussing the future directions of the study for endothelial dysfunction.

Roles of microRNAs in the liver

MicroRNAs (miRNAs) are a group of small non-coding RNAs that function as endogenous silencers of numerous target genes. Hundreds of human miRNAs have been identified in the human genome, and they are expressed in a tissue-specific manner and play important roles in cell proliferation, apoptosis, and differentiation. Numerous studies have shown that miRNAs participate in a variety of physiological and pathological processes in the liver. In this review, we will discuss the roles of miRNAs in the processes of liver regeneration (LR), liver immune responses, and the pathogenesis of liver fibrosis and hepatocellular carcinoma (HCC).

MicroRNA Signature in Alcoholic Liver Disease

Alcoholic liver disease (ALD) is a major global health problem. Chronic alcohol use results in inflammation and fatty liver, and in some cases, it leads to fibrosis and cirrhosis or hepatocellular carcinoma. Increased proinflammatory cytokines, particularly TNF alpha, play a central role in the pathogenesis of ALD. TNF alpha is tightly regulated at transcriptional and posttranscriptional levels. Recently, microRNAs (miRNAs) have been shown to modulate gene functions. The role of miRNAs in ALD is getting attention, and recent studies suggest that alcohol modulates miRNAs. Recently, we showed that alcohol induces miR-155 expression both in vitro (RAW 264.7 macrophage) and in vivo (Kupffer cells, KCs of alcohol-fed mice). Induction of miR-155 contributed to increased TNF alpha production and to the sensitization of KCs to produce more TNF alpha in response to LPS. In this paper, we summarize the current knowledge of miRNAs in ALD and also report increased expression of miR-155 and miR-132 in the total liver as well as in isolated hepatocytes and KCs of alcohol-fed mice. Our novel finding of the alcohol-induced increase of miRNAs in hepatocytes and KCs after alcohol feeding provides further insight into the evolving knowledge regarding the role of miRNAs in ALD.

MicroRNA response to environmental mutagens in liver

During the recent few years, microRNAs emerged as key molecules in the regulation of mammalian cell functions. It was also shown that their altered expression can promote pathologic conditions, such as cancer and other common diseases. Because environmental exposure to biological, chemical or physical agents may be responsible for human diseases, including cancer, uncovering relationships between exposure to environmental carcinogens and expression of microRNAs may help to disclose early mechanisms of disease and it may potentially lead to the development of useful indicators of toxic exposure or novel biomarkers for carcinogenicity testing. The unique expression profile of microRNAs in different types and at different stages of cancer coupled to their remarkable stability in tissues and in serum/plasma suggests that these little molecules may find application as sensitive biomarkers. This review will concentrate on the alterations in microRNA expression in response to environmental factors in relation to the risk of developing liver cancer.

Chronic ethanol consumption reduces adrenomedullin-induced relaxation in the isolated rat aorta

Adrenomedullin (AM) is a peptide that displays cardiovascular protective activity. We investigated the effects of chronic ethanol consumption on vascular reactivity to AM and the expression of AM system components in the rat aorta. Male Wistar rats were treated with ethanol (20% vol/vol) for 6 weeks. Vascular reactivity experiments were performed in the isolated rat aorta. Metalloproteinase-2 (MMP-2) levels were determined by gelatin zymography. Nitrite and nitrate generation was measured by chemiluminescence. Protein and mRNA levels of pre-pro-AM, calcitonin receptor-like receptor (CRLR) and RAMP1, 2, and 3 (receptor-activity-modifying proteins) were assessed by western blot and quantitative real-time polymerase chain reaction, respectively. Ethanol intake reduced AM-induced relaxation in endothelium-intact rat aortas, whereas calcitonin gene-related peptide-, acetylcholine-, and sodium nitroprusside-induced relaxation were not affected by ethanol intake. N(G)-nitro-l-arginine-methyl-ester (l-NAME), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, and tetraethylammonium reduced AM-induced relaxation in aortic rings from both control and ethanol-treated rats. Ethanol consumption did not alter basal levels of nitrate and nitrite, nor did it affect the expression of MMP-2 in the rat aorta. Ethanol consumption increased mRNA levels of pre-pro-AM and RAMP1. Protein levels of AM, CRLR, and RAMP1, 2, and 3 were not affected by ethanol consumption. The major findings of the present study are that ethanol consumption reduces the vascular relaxation induced by AM and changes the mRNA expression of the components of the AM system in the vasculature. This response could be one of the mechanisms by which ethanol predisposes individuals to vascular dysfunction and hypertension.

Heme oxygenase 1 is induced by miR-155 via reduced BACH1 translation in endothelial cells

Heme oxygenase 1 (HO-1) is a stress-inducible enzyme that degrades redox-active heme-producing biliverdin, carbon monoxide, and Fe(2+). It protects cells under various stress conditions and mediates anti-inflammatory and vasodilatory effects in the endothelium. The expression of HMOX1, the HO-1 gene, is highly inducible and its transcriptional regulation is complex. HMOX1 is induced by various proinflammatory stimuli via NF-κB in human endothelial cells, but functional NF-κB-binding elements have not been identified from the human gene. However, the regulation of HMOX1 by the antioxidant-response element is firmly established, with the transcription factor BACH1 serving as a repressor and Nrf2 as an enhancer. miR-155 is one of the TNFα-inducible endothelial microRNAs predicted to bind to the BACH1 mRNA. Oligonucleotides mimicking miR-155 efficiently inhibited BACH1 protein translation, resulting in a concentration-dependent increase in HMOX1 mRNA and protein expression in human umbilical vein endothelial cells. Moreover, endogenous miR-155 was upregulated by TNFα via an NF-κB-dependent mechanism with a subsequent increase in HMOX1 expression. We propose that increased HMOX1 expression in endothelial cells by TNFα results from miR-155-induced repression of BACH1 rather than direct induction of HMOX1 via NF-κB, and that miR-155 is cytoprotective during inflammation by elevating HO-1 expression in endothelial cells.

myMIR: a genome-wide microRNA targets identification and annotation tool

miRNA target genes prediction represents a crucial step in miRNAs functional characterization. In this context, the challenging issue remains predictions accuracy and recognition of false positive results. In this article myMIR, a web based system for increasing reliability of miRNAs predicted targets lists, is presented. myMIR implements an integrated pipeline for computing ranked miRNA::target lists and provides annotations for narrowing them down. The system relies on knowledge base data, suitably integrated in order to extend the functional characterization of targeted genes to miRNAs, by highlighting the search on over-represented annotation terms. Validation results show a dramatic reduction in the quantity of predictions and an increase in the sensitivity, when compared to other methods. This improves the predictions accuracy and allows the formulation of novel hypotheses on miRNAs functional involvement.

Ethanol consumption alters the expression and reactivity of adrenomedullin in the rat mesenteric arterial bed

AIMS

Adrenomedullin (AM) is a peptide that displays cardiovascular protective activity. We investigated the effects of chronic ethanol consumption on arterial blood pressure, vascular reactivity to AM and the expression of AM system components in the rat mesenteric arterial bed (MAB).

METHODS

Male Wistar rats were treated with ethanol (20% vol/vol) for 6 weeks. Systolic, diastolic and mean arterial blood pressure were monitored in conscious rats. Vascular reactivity experiments were performed on isolated rat MAB. Matrix metalloproteinase-2 (MMP-2) levels were determined by gelatin zymography. Nitrite and nitrate generation were measured by chemiluminescence. Protein and mRNA levels of pre-pro-AM, CRLR (calcitonin receptor-like receptor) and RAMP1, 2 and 3 (receptor activity-modifying proteins) were assessed by western blot and quantitative real-time polymerase chain reaction, respectively.

RESULTS

Ethanol consumption induced hypertension and decreased the relaxation induced by AM and acetylcholine in endothelium-intact rat MAB. Phenylephrine-induced contraction was increased in endothelium-intact MAB from ethanol-treated rats. Ethanol consumption did not alter basal levels of nitrate and nitrite, nor did it affect the expression of MMP-2 or the net MMP activity in the rat MAB. Ethanol consumption increased mRNA levels of pre-pro-AM and protein levels of AM in the rat MAB. Finally, no differences in protein levels or mRNA of CRLR and RAMP1, 2 and 3 were observed after treatment with ethanol.

CONCLUSION

Our study demonstrates that ethanol consumption increases blood pressure and the expression of AM in the vasculature and reduces the relaxation induced by this peptide in the rat MAB.

RNA-Seq analyses generate comprehensive transcriptomic landscape and reveal complex transcript patterns in hepatocellular carcinoma

RNA-seq is a powerful tool for comprehensive characterization of whole transcriptome at both gene and exon levels and with a unique ability of identifying novel splicing variants. To date, RNA-seq analysis of HBV-related hepatocellular carcinoma (HCC) has not been reported. In this study, we performed transcriptome analyses for 10 matched pairs of cancer and non-cancerous tissues from HCC patients on Solexa/Illumina GAII platform. On average, about 21.6 million sequencing reads and 10.6 million aligned reads were obtained for samples sequenced on each lane, which was able to identify >50% of all the annotated genes for each sample. Furthermore, we identified 1,378 significantly differently expressed genes (DEGs) and 24, 338 differentially expressed exons (DEEs). Comprehensive function analyses indicated that cell growth-related, metabolism-related and immune-related pathways were most significantly enriched by DEGs, pointing to a complex mechanism for HCC carcinogenesis. Positional gene enrichment analysis showed that DEGs were most significantly enriched at chromosome 8q21.3–24.3. The most interesting findings were from the analysis at exon levels where we characterized three major patterns of expression changes between gene and exon levels, implying a much complex landscape of transcript-specific differential expressions in HCC. Finally, we identified a novel highly up-regulated exon-exon junction in ATAD2 gene in HCC tissues. Overall, to our best knowledge, our study represents the most comprehensive characterization of HBV-related HCC transcriptome including exon level expression changes and novel splicing variants, which illustrated the power of RNA-seq and provided important clues for understanding the molecular mechanisms of HCC pathogenesis at system-wide levels.

microRNAs: Fad or future of liver disease

microRNAs (miRs) are small non-coding RNAs that regulate both mRNA and protein expression of target genes, which results in alterations in mRNA stability or translation inhibition. miRs influence at least one third of all human transcripts and are known regulators of various important cellular growth and differentiation factors. miRs have recently emerged as key regulatory molecules in chronic liver disease. This review details recent contributions to the field of miRs that influence liver development and the broad spectrum of disease, from non-alcoholic fatty liver disease to fibrosis/cirrhosis, with particular emphasis on hepatic stellate cells and potential use of miRs as therapeutic tools.

Upregulation of MiR-155 in nasopharyngeal carcinoma is partly driven by LMP1 and LMP2A and downregulates a negative prognostic marker JMJD1A

The role of microRNA-155 (miR-155) has been associated with oncogenesis of several human tumors. However the expression pattern of miR-155 has not been investigated in nasopharyngeal carcinoma (NPC). The present study was to assess miR-155 expression pattern and its possible function in NPC, to identify its targets and evaluate their clinical applications in NPC. MiR-155 was found to be upregulated in two Epstein-Barr virus (EBV) negative NPC derived cell lines CNE1 and TW03, as well as in NPC clinical samples by quantitative Real-time PCR and in situ hybridization detection. EBV encoded LMP1 and LMP2A could further enhance the expression of miR-155 in NPC CNE1 and TW03 cells. JMJD1A and BACH1 were identified as putative targets of miR-155 in a bioinformatics screen. Overexpression of miR-155 downregulated a luciferase transcript fused to the 3′UTR of JMJD1A and BACH1. MiR-155 mimic could downregulate the expression of JMJD1A and BACH1, while miR-155 inhibitor could upregulate JMJD1A expression in NPC cell lines. Moreover, downregulation of JMJD1A was significantly correlated with N stage in TNM classification (p = 0.023), a lower five-year survival rate (p = 0.021), and a lower five-year disease-free survival rate (p = 0.049) of NPC patients. Taken together, up-regulation of miR-155 in NPC is partly driven by LMP1 and LMP2A, and results in downregulation of JMJD1A, which is associated with N stage and poor prognosis of NPC patients. The potential of miR-155 and JMJD1A as therapeutic targets in NPC should be further investigated.

Regulation of Axl receptor tyrosine kinase expression by miR-34a and miR-199a/b in solid cancer

Axl is a receptor that induces proliferation, migration and invasion in cancer. In this study, we show that specific microRNAs (miRNAs) target the 3'-UTR of Axl. Luciferase-reporter assays with wild-type and deleted miR-34 and miR-199a/b seed sequences of Axl 3'-UTR confirmed the specificity of targeting. An inverse correlation between Axl protein and miR-34a expression in a panel of non-small cell lung cancer (NSCLC), colorectal cancer (CRC) and breast cancer (BRC) cell lines was observed, while miR-199a/b expression was completely suppressed. Pre-miR transfection inhibited in vitro migration and invasion and, in vivo, reduced the number of distant lung- or liver-metastases in a chorion-allantoic-membrane (CAM) assay. Moreover, methylation-specific PCR on bisulfite-converted DNA obtained from the cell lines showed that the miR-34a promoter methylation status was inversely correlated with its expression, and that miR-199a/b promoter regions were methylated in all cells tested. In a panel of NSCLC tissues (n=44), miR-34a and miR-199a/b were found to be downregulated and significantly co-expressed. A lower expression of all three miRs was significantly associated with squamous histotypes, and, in a preliminary series, NSCLC patients with miR-34a upregulation showed a positive association towards a longer survival. These results indicate that Axl receptor expression can be regulated by miR-34a and miR-199a/b, which are suppressed by promoter methylation in solid cancer cells.

Cigarette smoke exposure up-regulates endothelin receptor B in human pulmonary artery endothelial cells: molecular and functional consequences

BACKGROUND AND PURPOSE

Pulmonary arteries from smokers and chronic obstructive pulmonary disease patients show abnormal endothelium-dependent vascular reactivity. We studied the effect of cigarette smoke extract (CSE) on endothelin receptor B (ET(B) ) expression in human pulmonary artery endothelial cells (HPAECs) and its role in endothelial dysfunction.

EXPERIMENTAL APPROACH

ET(B) receptor expression was measured by real time RT-PCR, Western blot and immunofluorescence. Cell contraction, intracellular Ca(2+) , F/G-actin, RhoA activity, myosin light chain phosphorylation, ET, NO, thromboxane (Tx)A(2) and reactive oxygen species (ROS) were measured by traction microscopy, fluorescence microscopy, phalloidin fluorescence, colorimetric assay, Western blot, elisa and DCFDA fluorescence respectively.

KEY RESULTS

Cigarette smoke extract dose-dependently increased ET(B) receptor expression in HPAECs after 24h incubation. CSE-induced ET(B) expression was attenuated by bosentan, the ET(B) receptor antagonist BQ788, the Rho kinase antagonist Y27632 and the antioxidant N-acetylcysteine. A monoclonal antibody to ET-1 prevented CSE-induced ET(B) receptor overexpression. Twenty-four hour exposure to ET-1 dose-dependently increased ET(B) receptor expression, mimicking the effect of CSE. CSE-induced ET(B) receptor overexpression caused greater cell contraction; increased intracellular Ca(2+) ; increased F/G-actin and RhoA activity; increased myosin light chain phosphorylation; augmented TxA(2) and ROS production; and decreased NO after acute ET-1 (10nM). These effects were attenuated by bosentan, BQ788, Y27632 and N-acetylcysteine.

CONCLUSIONS AND IMPLICATION

Cigarette smoke extract induced ET(B) receptor overexpression by a feed forward mechanism mediated partly by ET release, promoting HPAEC dysfunction and attenuated by ET(B) receptor blockade, Rho kinase and ROS inhibition. These results provide support for the use of bosentan in CS-related endothelial dysfunction.

MicroRNA-125a/b-5p inhibits endothelin-1 expression in vascular endothelial cells

BACKGROUND

Endothelin-1 (ET-1) is considered to be one of the most potent and long-lasting vasoconstrictive peptides, but the mechanisms on the regulation of ET-1 expression are not fully understood.

METHOD AND RESULTS

In this study, we found that microRNA (miR)-125a-5p and miR-125b-5p are highly expressed in vascular endothelial cells (VECs), which can be regulated by oxidized low-density lipoprotein (oxLDL). To explore the function of miR-125a/b-5p in VECs, we examined the roles of potential targets of miR-125a/b-5p that could influence endothelium function. We found that both miR-125a/b-5p can suppress oxLDL-induced ET-1 expression by directly targeting 3' untranslated region of prepro-endothelin-1 (preproET-1) mRNA determined by luciferase reporter assay, western blot, and enzyme immunometric assay. Consistently, inhibitors of miR-125a/b-5p can directly enhance preproET-1 expression. The decreased expressions of miR-125a-5p and miR-125b-5p are negatively associated with upregulation of preproET-1 expression in aorta of stroke-prone spontaneously hypertensive rats (SHR-SPs).

CONCLUSION

Our finding demonstrated that endothelial miR-125a/b-5p inhibits ET-1 expression in VECs, which revealed a novel miRNA-mediated mechanism in vasomotor homeostasis.