Imaging Biological Pathways in Abdominal Aortic Aneurysms Using Positron Emission Tomography.

[Figure: see text].

Orai1 Channel Inhibition Preserves Left Ventricular Systolic Function and Normal Ca2+ Handling After Pressure Overload.

BACKGROUND: Orai1 is a critical ion channel subunit, best recognized as a mediator of store-operated Ca2+ entry (SOCE) in nonexcitable cells. SOCE has recently emerged as a key contributor of cardiac hypertrophy and heart failure but the relevance of Orai1 is still unclear. METHODS: To test the role of these Orai1 channels in the cardiac pathophysiology, a transgenic mouse was generated with cardiomyocyte-specific expression of an ion pore-disruptive Orai1R91W mutant (C-dnO1). Synthetic chemistry and channel screening strategies were used to develop 4-(2,5-dimethoxyphenyl)-N-[(pyridin-4-yl)methyl]aniline (hereafter referred to as JPIII), a small-molecule Orai1 channel inhibitor suitable for in vivo delivery. RESULTS: Adult mice subjected to transverse aortic constriction (TAC) developed cardiac hypertrophy and reduced ventricular function associated with increased Orai1 expression and Orai1-dependent SOCE (assessed by Mn2+ influx). C-dnO1 mice displayed normal cardiac electromechanical function and cellular excitation-contraction coupling despite reduced Orai1-dependent SOCE. Five weeks after TAC, C-dnO1 mice were protected from systolic dysfunction (assessed by preserved left ventricular fractional shortening and ejection fraction) even if increased cardiac mass and prohypertrophic markers induction were observed. This is correlated with a protection from TAC-induced cellular Ca2+ signaling alterations (increased SOCE, decreased [Ca2+]i transients amplitude and decay rate, lower SR Ca2+ load and depressed cellular contractility) and SERCA2a downregulation in ventricular cardiomyocytes from C-dnO1 mice, associated with blunted Pyk2 signaling. There was also less fibrosis in heart sections from C-dnO1 mice after TAC. Moreover, 3 weeks treatment with JPIII following 5 weeks of TAC confirmed the translational relevance of an Orai1 inhibition strategy during hypertrophic insult. CONCLUSIONS: The findings suggest a key role of cardiac Orai1 channels and the potential for Orai1 channel inhibitors as inotropic therapies for maintaining contractility reserve after hypertrophic stress.

Divergent effects of genetic and pharmacological inhibition of Nox2 NADPH oxidase on insulin resistance-related vascular damage.

Insulin resistance leads to excessive endothelial cell (EC) superoxide generation and accelerated atherosclerosis. The principal source of superoxide from the insulin-resistant endothelium is the Nox2 isoform of NADPH oxidase. Here we examine the therapeutic potential of Nox2 inhibition on superoxide generation in saphenous vein ECs (SVECs) from patients with advanced atherosclerosis and type 2 diabetes and on vascular function, vascular damage, and lipid deposition in apolipoprotein E-deficient (ApoE-/-) mice with EC-specific insulin resistance (ESMIRO). To examine the effect of genetic inhibition of Nox2, ESMIRO mice deficient in ApoE-/- and Nox2 (ESMIRO/ApoE-/-/Nox2-/y) were generated and compared with ESMIRO/ApoE-/-/Nox2+/y littermates. To examine the effect of pharmacological inhibition of Nox2, we administered gp91dstat or scrambled peptide to ESMIRO/ApoE-/- mice. SVECs from diabetic patients had increased expression of Nox2 protein with concomitant increase in superoxide generation, which could be reduced by the Nox2 inhibitor gp91dstat. After 12 wk Western diet, ESMIRO/ApoE-/-/Nox2-/y mice had reduced EC superoxide generation and greater aortic relaxation to acetylcholine. ESMIRO/ApoE-/-/Nox2-/y mice developed more lipid deposition in the thoraco-abdominal aorta with multiple foci of elastin fragmentation at the level of the aortic sinus and greater expression of intercellular adhesion molecule-1 (ICAM-1). Gp91dstat reduced EC superoxide and lipid deposition in the thoraco-abdominal aorta of ESMIRO/ApoE-/- mice without causing elastin fragmentation or increased ICAM-1 expression. These results demonstrate that insulin resistance is characterized by increased Nox2-derived vascular superoxide. Complete deletion of Nox2 in mice with EC insulin resistance exacerbates, whereas partial pharmacological Nox2 inhibition protects against, insulin resistance-induced vascular damage.

Correction to: Ectopic delivery of miR-200c diminishes hepatitis C virus infectivity through transcriptional and translational repression of Occludin.

The author would like to correct the errors in the online published article.

Ectopic delivery of miR-200c diminishes hepatitis C virus infectivity through transcriptional and translational repression of Occludin.

Occludin (OCLN) is an essential factor for HCV entry through interacting with other surface receptors. The aim of this study was to investigate the epigenetic regulation of Occludin expression and to study its impact on viral infectivity. microRNAs expression was assessed using qRT-PCR, while OCLN protein expression was investigated by indirect immunofluorescence and Western blotting. Viral infectivity was assessed by measuring viral-load using qRT-PCR. In silico analysis predicted that miR-200c targeted the OCLN 3'UTR, which was further experimentally confirmed. miR-122 was previously validated to target the 3'UTR of OCLN and was used as a control. We report a significant down-regulation of miR-200c in liver tissues of HCV-infected patients. Ectopic expression of both miR-122 and miR-200c in Huh7 cells reduced OCLN mRNA and protein levels. Viral infectivity was significantly reduced by miR-200c but enhanced by miR-122. This work sheds light on miR-200c as a novel regulator of HCV infectivity through the regulation of OCLN.

Side-by-side comparison of published small molecule inhibitors against thapsigargin-induced store-operated Ca2+ entry in HEK293 cells.

Calcium (Ca2+) is a key second messenger in eukaryotes, with store-operated Ca2+ entry (SOCE) being the main source of Ca2+ influx into non-excitable cells. ORAI1 is a highly Ca2+-selective plasma membrane channel that encodes SOCE. It is ubiquitously expressed in mammals and has been implicated in numerous diseases, including cardiovascular disease and cancer. A number of small molecules have been identified as inhibitors of SOCE with a variety of potential therapeutic uses proposed and validated in vitro and in vivo. These encompass both nonselective Ca2+ channel inhibitors and targeted selective inhibitors of SOCE. Inhibition of SOCE can be quantified both directly and indirectly with a variety of assay setups, making an accurate comparison of the activity of different SOCE inhibitors challenging. We have used a fluorescence based Ca2+ addback assay in native HEK293 cells to generate dose-response data for many published SOCE inhibitors. We were able to directly compare potency. Most compounds were validated with only minor and expected variations in potency, but some were not. This could be due to differences in assay setup relating to the mechanism of action of the inhibitors and highlights the value of a singular approach to compare these compounds, as well as the general need for biorthogonal validation of novel bioactive compounds. The compounds observed to be the most potent against SOCE in our study were: 7-azaindole 14d (12), JPIII (17), Synta-66 (6), Pyr 3 (5), GSK5503A (8), CM4620 (14) and RO2959 (7). These represent the most promising candidates for future development of SOCE inhibitors for therapeutic use.

Absence of association between host genetic mutations in the ORAI1 gene and COVID-19 fatality.

The calcium ion channel ORAI1 has emerged as a promising therapeutic target for the Coronavirus Disease 19 (COVID-19)-associated pneumonia, and a pharmacological inhibitor of ORAI1 has now reached clinical trials for severe COVID-19 pneumonia. Whether ORAI1 itself is associated with an increased risk for severe COVID-19 presentation is still unknown. Here, we employed genetic association analysis to investigate the potential association of host genetic polymorphisms of ORAI1 with the risk of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection and its associated COVID-19 fatality in UK Biobank participants from white British background. The analysis showed no significant association between ORAI1 variants and COVID-19 positivity or fatality, despite the well-established roles of ORAI1 in immune response and inflammation and the success of ORAI1 inhibition in clinical trials. Our results suggest that the host genetic polymorphisms of ORAI1 are unlikely to be implicated in the broad variability in symptoms severity among afflicted patients.

ORAI1 Ca2+ Channel as a Therapeutic Target in Pathological Vascular Remodelling.

In the adult, vascular smooth muscle cells (VSMC) are normally physiologically quiescent, arranged circumferentially in one or more layers within blood vessel walls. Remodelling of native VSMC to a proliferative state for vascular development, adaptation or repair is driven by platelet-derived growth factor (PDGF). A key effector downstream of PDGF receptors is store-operated calcium entry (SOCE) mediated through the plasma membrane calcium ion channel, ORAI1, which is activated by the endoplasmic reticulum (ER) calcium store sensor, stromal interaction molecule-1 (STIM1). This SOCE was shown to play fundamental roles in the pathological remodelling of VSMC. Exciting transgenic lineage-tracing studies have revealed that the contribution of the phenotypically-modulated VSMC in atherosclerotic plaque formation is more significant than previously appreciated, and growing evidence supports the relevance of ORAI1 signalling in this pathologic remodelling. ORAI1 has also emerged as an attractive potential therapeutic target as it is accessible to extracellular compound inhibition. This is further supported by the progression of several ORAI1 inhibitors into clinical trials. Here we discuss the current knowledge of ORAI1-mediated signalling in pathologic vascular remodelling, particularly in the settings of atherosclerotic cardiovascular diseases (CVDs) and neointimal hyperplasia, and the recent developments in our understanding of the mechanisms by which ORAI1 coordinates VSMC phenotypic remodelling, through the activation of key transcription factor, nuclear factor of activated T-cell (NFAT). In addition, we discuss advances in therapeutic strategies aimed at the ORAI1 target.

A missense mutation of ErbB2 produces a novel mouse model of stillbirth associated with a cardiac abnormality but lacking abnormalities of placental structure.

BACKGROUND: In humans, stillbirth describes the death of a fetus before birth after 28 weeks gestation, and accounts for approximately 2.6 million deaths worldwide annually. In high-income countries, up to half of stillbirths have an unknown cause and are described as "unexplained stillbirths"; this lack of understanding impairs efforts to prevent stillbirth. There are also few animal models of stillbirth, but those that have been described usually have significant placental abnormalities. This study describes a novel mutant murine model of fetal death with atrial conduction block due to an ErbB2 missense mutation which is not associated with abnormal placental morphology. METHODS: Phenotypic characterisation and histological analysis of the mutant mouse model was conducted. The mRNA distribution of the early cardiomyocyte marker Nkx2-5 was assessed via in situ hybridisation. Cardiac structure was quantified and cellular morphology evaluated by electron microscopy. Immunostaining was employed to quantify placental structure and cell characteristics on matched heterozygous and homozygous mutant placental samples. RESULTS: There were no structural abnormalities observed in hearts of mutant embryos. Comparable Nkx2-5 expression was observed in hearts of mutants and controls, suggesting normal cardiac specification. Additionally, there was no significant difference in the weight, placenta dimensions, giant cell characteristics, labyrinth tissue composition, levels of apoptosis, proliferation or vascularisation between placentas of homozygous mutant mice and controls. CONCLUSION: Embryonic lethality in the ErbB2 homozygous mutant mouse cannot be attributed to placental pathology. As such, we conclude the ErbB2M802R mutant is a model of stillbirth with a non-placental cause of death. The mechanism of the atrial block resulting from ErbB2 mutation and its role in embryonic death is still unclear. Studying this mutant mouse model could identify candidate genes involved in stillbirth associated with structural or functional cardiac defects.

Disruption of Claudin-1 Expression by miRNA-182 Alters the Susceptibility to Viral Infectivity in HCV Cell Models.

HCV entry involves a complex interplay between viral and host molecules. During post-binding interactions, the viral E2 complexes with CD81 receptor for delivery to the tight junction proteins CLDN1 and OCLN, which aid in viral internalization. Targeting HCV entry receptors represents an appealing approach to inhibit viral infectivity. This study aimed at investigating the impact of targeting CLDN1 by microRNAs on HCV infectivity. miR-155 was previously shown to target the 3'UTR of CLDN1 mRNA. Therefore, miR-155 was used as a control in this study. In-silico analysis and luciferase reporter assay were utilized to identify potential targeting miRNAs. The impact of the identified miRNAs on CLDN1 mRNA and protein expression was examined by qRT-PCR, indirect immunofluorescence and western blotting, respectively. The role of the selected miRNAs on HCV infectivity was assessed by measuring the viral load following the ectopic expression of the selected miRNAs. miR-182 was identified in-silico and by experimental validation to target CLDN1. Both miR-155 and miR-182 inhibited CLDN1 mRNA and protein expression in infected Huh7 cells. Ectopic expression of miR-155 increased, while miR-182 reduced the viral load. In conclusion, despite repressing CLDN1, the impact of miR-155 and miR-182 on HCV infectivity is contradictory. Ectopic miR-182 expression is suggested as an upstream regulator of the entry factor CLDN1, harnessing HCV infection.

miR-590-3p Promotes Ovarian Cancer Growth and Metastasis via a Novel FOXA2-Versican Pathway.

miRNAs play important roles in gene regulation, and their dysregulation is associated with many diseases, including epithelial ovarian cancer (EOC). In this study, we determined the expression and function of miR-590-3p in EOC. miR-590-3p levels were higher in high-grade carcinoma when compared with low-grade or tumors with low malignant potential. Interestingly, plasma levels of miR-590-3p were significantly higher in patients with EOC than in subjects with benign gynecologic disorders. Transient transfection of miR-590-3p mimics or stable transfection of mir-590 increased cell proliferation, migration, and invasion. In vivo studies revealed that mir-590 accelerated tumor growth and metastasis. Using a cDNA microarray, we identified forkhead box A2 (FOXA2) and versican (VCAN) as top downregulated and upregulated genes by mir-590, respectively. miR-590-3p targeted FOXA2 3' UTR to suppress its expression. In addition, knockdown or knockout of FOXA2 enhanced cell proliferation, migration, and invasion. Overexpression of FOXA2 decreased, whereas knockout of FOXA2 increased VCAN mRNA and protein levels, which was due to direct binding and regulation of the VCAN gene by FOXA2. Interrogation of the TCGA ovarian cancer database revealed a negative relationship between FOXA2 and VCAN mRNA levels in EOC tumors, and high FOXA2/low VCAN mRNA levels in tumors positively correlated with patient survival. Finally, overexpression of FOXA2 or silencing of VCAN reversed the effects of mir-590. These findings demonstrate that miR-590-3p promotes EOC development via a novel FOXA2-VCAN pathway.Significance: Low FOXA2/high VCAN levels mediate the tumor-promoting effects of miR-590-3p and negatively correlate with ovarian cancer survival. Cancer Res; 78(15); 4175-90. ©2018 AACR.

New genetic variants of LATS1 detected in urinary bladder and colon cancer.

LATS1, the large tumor suppressor 1 gene, encodes for a serine/threonine kinase protein and is implicated in cell cycle progression. LATS1 is down-regulated in various human cancers, such as breast cancer, and astrocytoma. Point mutations in LATS1 were reported in human sarcomas. Additionally, loss of heterozygosity of LATS1 chromosomal region predisposes to breast, ovarian, and cervical tumors. In the current study, we investigated LATS1 genetic variations including single nucleotide polymorphisms (SNPs), in 28 Egyptian patients with either urinary bladder or colon cancers. The LATS1 gene was amplified and sequenced and the expression of LATS1 at the RNA level was assessed in 12 urinary bladder cancer samples. We report, the identification of a total of 29 variants including previously identified SNPs within LATS1 coding and non-coding sequences. A total of 18 variants were novel. Majority of the novel variants, 13, were mapped to intronic sequences and un-translated regions of the gene. Four of the five novel variants located in the coding region of the gene, represented missense mutations within the serine/threonine kinase catalytic domain. Interestingly, LATS1 RNA steady state levels was lost in urinary bladder cancerous tissue harboring four specific SNPs (16045 + 41736 + 34614 + 56177) positioned in the 5'UTR, intron 6, and two silent mutations within exon 4 and exon 8, respectively. This study identifies novel single-base-sequence alterations in the LATS1 gene. These newly identified variants could potentially be used as novel diagnostic or prognostic tools in cancer.