Modulation of amyloid precursor protein cleavage by γ-secretase activating protein through phase separation.

Aberrant cleavage of amyloid precursor protein (APP) by γ-secretase is closely associated with Alzheimer's disease (AD). γ-secretase activating protein (GSAP) specifically promotes γ-secretase­mediated cleavage of APP. However, the underlying mechanism remains enigmatic. Here, we demonstrate that the 16-kDa C-terminal fragment of GSAP (GSAP-16K) undergoes phase separation in vitro and forms puncta-like condensates in cells. GSAP-16K exerts dual modulation on γ-secretase cleavage; GSAP-16K in dilute phase increases APP­C-terminal 99-residue fragment (C99) cleavage toward preferred production of ß-amyloid peptide 42 (Aß42), but GSAP-16K condensates reduce APP-C99 cleavage through substrate sequestration. Notably, the Aß42/Aß40 ratio is markedly elevated with increasing concentrations of GSAP-16K. GSAP-16K stably associates with APP-C99 through specific sequence elements. These findings mechanistically explain GSAP-mediated modulation of γ-secretase activity that may have ramifications on the development of potential therapeutics.

Circular RNA microarray expression profile in 3,4-benzopyrene/angiotensin II-induced abdominal aortic aneurysm in mice.

Abdominal aortic aneurysm (AAA) is an unpredictable but lethal disease that poses a therapeutic dilemma. Circular RNAs (circRNAs), whose functional roles as transcriptional regulators and microRNA (miRNA) sponges have been shown in former studies, are potential biomarkers for many diseases. AAA in male C57BL/6 J mice was induced by coadministration of angiotensin II (Ang II) and 3,4-benzopyrene (BaP). The circRNA expression profiling was performed using two samples from the control group and two samples from the AAA group. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to confirm the reliability of the microarray results. Among the 14 236 detected circRNAs, 413 showed obvious expression changes (fold change ≥ 2; P < 0.05) between the BaP/Ang II-induced AAA group and control group. Of the 413 that showed significant changes, 271 were upregulated, while the other 142 were downregulated. The expression levels of 10 circRNAs were validated by qRT-PCR. The interactions of the differentially expressed circRNAs with miRNAs were predicted. Immunofluorescence showed prominent vascular smooth muscle cell apoptosis in abdominal aortic tissues in the BaP/Ang II group. Furthermore, a circRNA-miRNA coexpression network based on six apoptosis-related circRNAs was built. The genes regulated by the network mapped to several pathways, including apoptosis, the IL-17 signaling pathway, and vascular endothelial growth factor signaling pathway, all of which are related to AAA formation. This study performed circRNA expression profiling in AAA and the results specifically predicted the regulatory role of circRNAs in AAA pathogenesis.

Comparison of survival for cardiac resynchronization therapy in atrial fibrillation patients with or without atrio-ventricular junction ablation and patients in sinus rhythm: a systematic review and network meta-analysis.

Cardiac resynchronization therapy (CRT) has been established to improve prognosis for patients with heart failure and SR. Whether the benefit observed with CRT on survival was similar in AF patients receiving atrio-ventricular junction ablation (AVJA) or not and patients in SR remains uncertain. The primary purpose of this study was to comprehensively evaluate the impact of CRT on the outcome of survival in atrial fibrillation (AF) patients with or without AVJA and patients in sinus rhythm (SR). Medline, Embase, and the Cochrane Library were searched for inception through June 31, 2018. Two reviewers independently evaluated and extracted data from 4 studies, including a total of 7896 CRT recipients, composed of 554 AF with AVJA (CRT+AF+AVJA), 1071 AF without AVJA (CRT+AF-AVJA), and 6244 SR (CRT+SR). The benefit on survival was comparable between CRT+AF+AVJA and CRT+SR (HR = 1.00; 95% CI, 0.73-1.40). CRT+AF+AVJA and CRT+SR both were associated with significantly higher survival compared with CRT+AF-AVJA, with hazard ratio of 0.64 (95% CI, 0.46-0.91) and 0.63 (95% CI, 0.53-0.75), respectively. The survival benefit was similar for patients with CRT+AF+AVJA and CRT+SR, while it was 36-37% high as compared to CRT+AF-AVJA. Whether aggressive intervention with AVJA in AF should be routinely combined with CRT despite rate-slowing drug treatment is helpful deserves further studies.

Very early recurrence predicts long-term outcome in patients after atrial fibrillation catheter ablation: a prospective study.

BACKGROUND: Long-term recurrence (LR) is a tendency that re-occurs within 3 months after catheter ablation for atrial fibrillation (AF). Whether very early recurrence (VER) within 7 days of post ablation is a prognostic factor of LR or not is unclear. For this reason, present study sought to examine the relationship between VER and LR. METHODS: In this prospective analysis 378 consecutive patients underwent an initial catheter ablation for paroxysmal or persistent AF. The association between VER and LR was analyzed by univariate and multivariate Cox regression, as well as time-dependent receiver operator characteristic (ROC) analysis. RESULTS: After a mean follow-up of 14.71 ± 8.58 months, 81 (65.90%) patients with VER experienced LR and were associated with lower event of free survival from LR (Log rank test, P < 0.001). Multivariate Cox regression analysis revealed that VER (HR = 7.02, 95% CI = 4.78-10.31; P < 0.001), left atrial enlargement (HR = 2.92, 95% CI = 1.88-4.54; P < 0.001), tendency in advanced age (HR = 1.50, 95% CI = 0.99-2.28; P = 0.054), and tendency in male (HR = 0.71, 95% CI = 0.50-1.01; P = 0.060) were independent predictors of LR. According to time-dependent ROC analysis, it was found that VER was more sensitive than common risk factors in predicting LR (0.74 vs 0.66, P < 0.001) and combination model further improved the C statistic for predicting LR (0.82 vs 0.66, P < 0.001). CONCLUSIONS: After a single procedure of catheter ablation, patients with VER were strongly associated with LR and combination of VER and common risk factors could further improve prediction of patients who were at high risk for LR.

Macrophage migration inhibitory factor promoter polymorphisms (-794 CATT5-8): Relationship with soluble MIF levels in coronary atherosclerotic disease subjects.

BACKGROUND: We analyzed the relationship of -794 CATT5-8 MIF polymorphisms with soluble MIF in Coronary Atherosclerotic Disease (CAD) patients. METHODS: A total of 256 patients selected, on which 186 normal-coronary and 70 Coronary artery disease subjects, were recruited in the study (Retrospectively registered). Genotyping of -794 CATT5-8 polymorphisms were performed by PCR and DNA sequencing. Serum MIF levels were measured using an ELISA kit. Patients were classified by coronary angiogram, and CAD based on Gensini's integral degree (angiographic scoring system). RESULTS: The allele frequency and genotype frequency of -794 CATT5-8 did not show any differences in normal-coronary subjects and CAD subjects. In CAD patients, serum MIF levels was lower in CATT (5) subjects than in CATT (7) subjects, while the genotype of -794 CATT5-8 did not show differences in serum MIF levels. In addition, we found a decrease in serum MIF levels in carriers of the (5/5) genotypes the -794 CATT5-8 MIF polymorphisms, although it was not significant. There was no relationship of CAD class and the allele frequency of -794 CATT5-8. CONCLUSIONS: This study found no association between CAD class and -794 CATT5-8 MIF polymorphisms with soluble MIF levels in CAD Subjects. TRIAL REGISTRATION: NCT01750502 (November 2012, Retrospectively registered).

Assessment of fetal left atrial volume and function using a novel left atrial volume tracking method.

BACKGROUND: Several fetal cardiovascular structural defects may alter the hemodynamics of the cardiac chambers resulting in changes in chamber sizes. Quantitative measurements of the sizes of cardiac chambers can augment the diagnostic power of fetal echocardiography. AIMS: Using a new left atrial volume tracking (LAVT) method, time-left atrial volume curves (TLAVCs) can be automatically obtained. The goal of this study was to examine whether this method can be used to evaluate left atrial volume (LAV) and provide reference values for LAV and indices of left atrial function in normal human fetuses. METHODS: Two hundred and four normal human fetuses were enrolled. Using LAVT, the maximal left atrial volume (LAVmax) and minimal left atrial volume (LAVmin) were measured from TLAVCs. Left atrial ejection fraction (EF) was calculated. The maximal left atrial area (LAAmax) and minimal left atrial area (LAAmin) were measured using manual method tracing. RESULTS: Between 21 and 40 weeks, mean LAVmax increased from 0.27 ml to 4.15 ml, and mean LAVmin increased from 0.13 ml to 2.26 ml, respectively, while the EF remained stable at around 0.43. From 21 to 40 weeks, mean LAAmax increased from 0.61 cm2 to 2.64 cm2, and mean LAAmin increased from 0.34 cm2 to 1.53 cm2. CONCLUSIONS: This study establishes reference values for fetal LAV during the second half of gestation. The LAVT method appears to be feasible in estimating fetal LAV and shows potential for assessing left atrial function.

Molecular basis for isoform-selective inhibition of presenilin-1 by MRK-560.

Inhibition of γ-secretase activity represents a potential therapeutic strategy for Alzheimer's disease (AD). MRK-560 is a selective inhibitor with higher potency for Presenilin 1 (PS1) than for PS2, the two isoforms of the catalytic subunit of γ-secretase, although the underlying mechanism remains elusive. Here we report the cryo-electron microscopy (cryo-EM) structures of PS1 and PS2-containing γ-secretase complexes with and without MRK-560 at overall resolutions of 2.9-3.4 Å. MRK-560 occupies the substrate binding site of PS1, but is invisible in PS2. Structural comparison identifies Thr281 and Leu282 in PS1 to be the determinant for isoform-dependent sensitivity to MRK-560, which is confirmed by swapping experiment between PS1 and PS2. By revealing the mechanism for isoform-selective inhibition of presenilin, our work may facilitate future drug discovery targeting γ-secretase.

Antithrombin III Alleviates Myocardial Ischemia/Reperfusion Injury by Inhibiting Excessive Autophagy in a Phosphoinositide 3-Kinase/Akt-Dependent Manner.

Autophagy is fundamental to myocardial ischemia/reperfusion (I/R) injury. Antithrombin III (AT) has been shown to protect cardiomyocytes against I/R injury; however, it is unknown whether it modulates autophagy. The objective of this study was to investigate whether AT regulates autophagy during I/R injury and, if so, to identify the potential mechanism involved. Our study showed that AT attenuated I/R injury in vivo and hypoxia/reoxygenation (H/R) injury in vitro. Autophagy was increased both in H9C2 cardiomyocytes during H/R injury and in mouse hearts following I/R injury. The stimulation of autophagy by rapamycin attenuated the protective effect of AT against H9C2 cell injury, indicating that autophagy is involved in the protective role of AT. Furthermore, the cardioprotective effects of AT were abolished by A6730, a specific Akt inhibitor. This study shows that AT exhibits cardioprotective effects by modulating autophagy during I/R injury in a phosphoinositide 3-kinase/Akt-dependent manner.

RNA sequencing revealing the role of AMP-activated protein kinase signaling in mice myocardial ischemia reperfusion injury.

Long non-coding RNAs (lncRNA) and circular RNAs (circRNA) that sponge miRNAs could indirectly regulate gene expression, contributing to certain biological processes. This study aimed to investigate the role of non-coding RNAs in the pathogenesis of myocardial ischemia reperfusion-injury (MIRI). MIRI in male C57B/6J mice was induced by left anterior descending coronary artery ligation occlusion for 30 min, and 4 h of reperfusion. RNA sequencing was performed to obtain the mRNA and non-coding RNA expression profiles of the MIRI and sham groups. Bioinformatic methods were used to analyze the co-expression RNAs, miRNA binding sites and competitive endogenous RNA (ceRNA) pairs. Differentially expressed RNAs were identified with a cutoff fold change > 2 and p < 0.05. A total of 64 mRNAs were upregulated and 98 mRNAs were downregulated, and 10 lncRNAs were upregulated and 10 lncRNAs were downregulated. All altered (p < 0.05) mRNAs were selected for gene ontology and pathway analysis. The AMP-activated protein kinase (AMPK) signaling pathway was enriched in the downregulated genes, and the activation of AMPK was confirmed by western blotting. The lncRNA co-expression network and ceRNA network base on genes in AMPK signaling pathway were then constructed, revealing that ENSMUST00000147762.7 and TUCP_000184 might be key regulators in MIRI induced AMPK activation. The expression levels of AMPK signaling-related RNAs and those involved in the ceRNA network were validated using qRT-PCR. Overall, this study identified potential new targets on AMPK signaling in MIRI.

Retinol palmitate protects against myocardial ischemia/reperfusion injury via reducing oxidative stress and inhibiting apoptosis.

The purpose of this study was to determine whether retinol palmitate could protect against myocardial ischemia/reperfusion (I/R) injury and explore the underlying mechanism. Retinol palmitate reduced the level of reactive oxygen species and prevented cellular apoptosis. In vivo, retinol palmitate increased superoxide dismutase (SOD) activity and reduced the level of malondialdehyde in I/R mice. Retinol palmitate also decreased myocardial infarct size and reduced cellular apoptosis by suppressing the expression of proapoptotic-related proteins and increasing that of SOD-related proteins. Our results suggest that retinol palmitate pretreatment has a protective effect against myocardial I/R injury by maintaining the balance between intracellular oxidants and antioxidants.

Significance of aquaporins' expression in the prognosis of gastric cancer.

Gastric carcinoma is one of the most lethal malignancy at present with leading cause of cancer-related deaths worldwide. Aquaporins (AQPs) are a family of small, integral membrane proteins, which have been evidenced to play a crucial role in cell migration and proliferation of different cancer cells including gastric cancers. However, the aberrant expression of specific AQPs and its correlation to detect predictive and prognostic significance in gastric cancer remains elusive. In the present study, we comprehensively explored immunohistochemistry based map of protein expression profiles in normal tissues, cancer and cell lines from publicly available Human Protein Atlas (HPA) database. Moreover, to improve our understanding of general gastric biology and guide to find novel predictive prognostic gastric cancer biomarker, we also retrieved 'The Kaplan-Meier plotter' (KM plotter) online database with specific AQPs mRNA to overall survival (OS) in different clinicopathological features. We revealed that ubiquitous expression of AQPs protein can be effective tools to generate gastric cancer biomarker. Furthermore, high level AQP3, AQP9, and AQP11 mRNA expression were correlated with better OS in all gastric patients, whereas AQP0, AQP1, AQP4, AQP5, AQP6, AQP8, and AQP10 mRNA expression were associated with poor OS. With regard to the clinicopathological features including Laurens classification, clinical stage, human epidermal growth factor receptor 2 (HER2) status, and different treatment strategy, we could illustrate significant role of individual AQP mRNA expression in the prognosis of gastric cancer patients. Thus, our results indicated that AQP's protein and mRNA expression in gastric cancer patients provide effective role to predict prognosis and act as an essential agent to therapeutic strategy.

Effects of macrophage migration inhibitory factor on cardiac reperfusion injury in mice with depression induced by constant-darkness.

RATIONALE: Depression is associated with coronary artery disease and increases adverse outcomes and mortality in patients with acute myocardial infarction, but the underlying pathophysiological mechanisms remain unclear. OBJECTIVE: To evaluate the effect of macrophage migration inhibitory factor (MIF) on cardiac ischemia-reperfusion (I/R) injury in mice with constant darkness-induced depression. METHODS AND RESULTS: Twenty C57BL/6 mice (8 weeks old, male) were randomly divided into 2 groups: one group was housed in a 12h light/dark cycle environment (LD) and the other in a constant darkness environment (DD). After 3 weeks, constant darkness-exposed (DD) mice displayed depression-like behavior as indicated by increased immobility in the forced swim test (FST) and lower sucrose preference rate. Western blotting revealed cardiac MIF expression was significantly lower in the DD mice than that in the LD mice. Next, 84 mice were randomly divided into 4 groups: LD sham group, LD I/R group, DD sham group, and DD I/R group. Following ischemia and reperfusion, mice in the DD I/R group had a larger infarct area and lower heart function index than mice in the LD I/R group (P < 0.05 for both). The cardiac pAMPK and pACC expression levels of the DD I/R group were also lower in the DD I/R group (P < 0.05). CONCLUSION: DD-induced depression might cause decreased expression of MIF in the heart, resulting in downregulation of MIF-AMPK signaling and a subsequent adverse outcome after a cardiac I/R injury.

Astragaloside IV Attenuated 3,4-Benzopyrene-Induced Abdominal Aortic Aneurysm by Ameliorating Macrophage-Mediated Inflammation.

Abdominal aortic aneurysm (AAA), characterized by macrophage infiltration-mediated inflammation and oxidative stress, is a potentially fatal disease. Astragaloside IV (AS-IV) has been acknowledged to exhibit antioxidant and anti-inflammatory properties. This study was designed to investigate the protective effect of AS-IV against AAA formation induced by 3,4-benzopyrene (Bap) and angiotensin II (Ang II), and to explore probable mechanisms. Results showed that AS-IV decreased AAA formation, and reduced macrophage infiltration and expression of matrix metalloproteinase. Furthermore, AS-IV abrogated Bap-/Ang II-induced NF-κB activation and oxidative stress. In vitro, AS-IV inhibition of macrophage activation and NF-κB was correlated with increased phosphorylation of phosphatidylinositol 3-kinase (PI3-K)/AKT. Together, our findings suggest that AS-IV has potential as an intervention in the formation of AAA. HIGHLIGHTS: (1)The protective effect of Astragaloside IV (AS-IV) on abdominal aortic aneurysm (AAA) is associated with its suppressing effects on inflammation in the aortic wall.(2)AS-IV abrogated 3,4-benzopyrene (Bap)/angiotensin II (Ang II)-induced nuclear factor-κB (NF-κB) activation and oxidative stress.(3)AS-IV inhibited Bap-induced RAW264.7 macrophage cells activation by inhibiting oxidative stress and NF-κB activation through phosphatidylinositol 3-kinase (PI3-K)/AKT pathway.AS-IV is a potential preventive agent for cigarette smoking-related AAA.

Relation of phosphodiesterase type 5 inhibitors and malignant melanoma: a meta-analysis and systematic review.

Data on the association between using PDE5 inhibitors and malignant melanoma are conflicting. To estimate the relation of using PDE5 inhibitors with risk of malignant melanoma, Medline (Ovid) and Embase (Ovid) databases were searched up to February 2017, and a random effects model was used to calculate the summary risk estimates. Five observational studies were included. Five studies reports encompassed a total of 15,979 melanoma cases occurring among 1, 188,414 participants. The pooled multivariable-adjusted RR of melanoma in patients with using PDE5 inhibitors was 1.12 (95% CI: 1.03-1.21, I2 = 0.48). Findings from this systematic review support that PDE5 inhibitor use is associated with increased risk of melanoma in ED patients, the result remains inclusive and warrants further study in the future.

Amifostine Pretreatment Attenuates Myocardial Ischemia/Reperfusion Injury by Inhibiting Apoptosis and Oxidative Stress.

The present study was aimed at investigating the effect of amifostine on myocardial ischemia/reperfusion (I/R) injury of mice and H9c2 cells cultured with TBHP (tert-butyl hydroperoxide). The results showed that pretreatment with amifostine significantly attenuated cell apoptosis and death, accompanied by decreased reactive oxygen species (ROS) production and lower mitochondrial potential (ΔΨm). In vivo, amifostine pretreatment alleviated I/R injury and decreased myocardial apoptosis and infarct area, which was paralleled by increased superoxide dismutase (SOD) and reduced malondialdehyde (MDA) in myocardial tissues, increased Bcl2 expression, decreased Bax expression, lower cleaved caspase-3 level, fewer TUNEL positive cells, and fewer DHE-positive cells in heart. Our results indicate that amifostine pretreatment has a protective effect against myocardial I/R injury via scavenging ROS.

Microarray Analysis Reveals a Potential Role of lncRNA Expression in 3,4-Benzopyrene/Angiotensin II-Activated Macrophage in Abdominal Aortic Aneurysm.

Abdominal aortic aneurysm (AAA) is a fatal disease, and exposure to 3,4-benzopyrene (Bap) is closely related to the development of AAA. We have found that Bap could impair the biological function of endothelial progenitor cells (EPCs), which are associated with the occurrence of AAA. We have also demonstrated that macrophage activation plays a key role in Bap-induced AAA, but the mechanism is unknown. Here, we used a mouse lncRNA array to investigate the expression signatures of lncRNAs and mRNAs in Bap-activated macrophage. A total of 457 lncRNAs and 219 mRNAs were found to be differentially expressed. The function of differential mRNAs was determined by pathway and Gene Ontology analysis. Eight pathways associated with inflammation were upregulated, and seven pathways including cell apoptosis were downregulated. It was worth noting that AGE-RAGE pathway, which was involved in Bap-induced EPC dysfunction, was significantly upregulated in Bap-activated macrophage and may contribute to AAA formation. Thus, lncRNAs may exert a key role in activated macrophages and intervene the core lncRNAs and may inhibit the occurrence of a series of cascade reactions in the macrophages, which may provide potential targets for AAA caused by smoking.