Tyrosine phosphorylation of Kv1.5 is upregulated in intrauterine growth retardation rats with exaggerated pulmonary hypertension

Effects of uteroplacental insufficiency on cardiac development in growth-restricted newborn rats

Fetal growth restriction (FGR) is associated with reduced cardiac function in neonates. Uteroplacental insufficiency (UPI) is the most common cause of FGR. The mechanisms underlying these alterations remain unknown. We hypothesized that UPI would influence cardiac development in offspring rats. Through this study, we evaluated the effects of UPI during pregnancy on heart histology and pulmonary hypertension in growth-restricted newborn rats. On gestation Day 18, either UPI was induced through bilateral uterine vessel ligation (FGR group) or sham surgery (control group) was performed. The right middle lobe of the lung and the heart were harvested for histological and immunohistochemical evaluation on postnatal days 0 and 7. The FGR group exhibited significantly lower body weight, hypertrophy and degeneration of cardiomyocytes, increased intercellular spaces between the cardiomyocytes and collagen deposition, and decreased glycogen deposition and HNK-1 expression compared with the control group on postnatal days 0 and 7. These results suggest that neonates with FGR may have inadequate myocardial reserves, which may cause subsequent cardiovascular compromise in future life. Further studies are required to evaluate the hemodynamic changes in these growth-restricted neonates.

Pulmonary Vascular Remodeling in Pulmonary Hypertension

Pulmonary vascular remodeling is the critical structural alteration and pathological feature in pulmonary hypertension (PH) and involves changes in the intima, media and adventitia. Pulmonary vascular remodeling consists of the proliferation and phenotypic transformation of pulmonary artery endothelial cells (PAECs) and pulmonary artery smooth muscle cells (PASMCs) of the middle membranous pulmonary artery, as well as complex interactions involving external layer pulmonary artery fibroblasts (PAFs) and extracellular matrix (ECM). Inflammatory mechanisms, apoptosis and other factors in the vascular wall are influenced by different mechanisms that likely act in concert to drive disease progression. This article reviews these pathological changes and highlights some pathogenetic mechanisms involved in the remodeling process.

Peptide Inhibitors of Kv1.5: An Option for the Treatment of Atrial Fibrillation

The human voltage gated potassium channel Kv1.5 that conducts the IKur current is a key determinant of the atrial action potential. Its mutations have been linked to hereditary forms of atrial fibrillation (AF), and the channel is an attractive target for the management of AF. The development of IKur blockers to treat AF resulted in small molecule Kv1.5 inhibitors. The selectivity of the blocker for the target channel plays an important role in the potential therapeutic application of the drug candidate: the higher the selectivity, the lower the risk of side effects. In this respect, small molecule inhibitors of Kv1.5 are compromised due to their limited selectivity. A wide range of peptide toxins from venomous animals are targeting ion channels, including mammalian channels. These peptides usually have a much larger interacting surface with the ion channel compared to small molecule inhibitors and thus, generally confer higher selectivity to the peptide blockers. We found two peptides in the literature, which inhibited IKur: Ts6 and Osu1. Their affinity and selectivity for Kv1.5 can be improved by rational drug design in which their amino acid sequences could be modified in a targeted way guided by in silico docking experiments.

Transgenerational inheritance of promoter methylation changes in extrauterine growth restriction-induced pulmonary arterial pressure disorders

Background

This study aimed to investigate the influence of extrauterine growth restriction (EUGR) on pulmonary arterial pressure (PAP) and the transgenerational inheritance of promoter methylation changes in pulmonary vascular endothelial cells (PVECs) of 2 consecutive generations under EUGR stress.

Methods

After modeling, PAP values of F1 and F2 pups were investigated at 9-week-old. The methyl-DNA immune precipitation chip was used to analyze DNA methylation profiling. Differential enrichment peaks (DEPs) and regions of interest (ROIs) were identified, based on which Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and reactome pathway enrichments were analyzed.

Results

The F1 male rats in the EUGR group had significantly increased PAP levels compared to the control group; however, this increase was not observed in female rats. Interestingly, in F2 female rats, the EUGR group had decreased PAP. In the X chromosome of the F1 males, there were 16 differential ROI genes in the F1 generation, while in F2 females, there were 86 differential ROI genes. Similarly, there were 105 DEPs in the F1 generation and 38 DEPs in the F2 generation. In combination with the 5 common ROIs and 14 common DEPs, 18 genes were regarded as the key candidate genes associated with hereditable PAP variation in the EUGR model. Enrichment analysis showed that synaptic and neurotransmitter relative pathways might be involved in the process of EUGR-induced PAH development. Among common DEPs, Smad1 and Serpine1 were also found in 102 PAH-associated genes in the MalaCards database.

Conclusions

Together, there is a transgenerational inheritance of promoter methylation changes in the X chromosome in EUGR-induced PAP disorders, which involves the participation of synaptic and neurotransmitter relative pathways. Also, attenuated methylation of Smad1 and Serpine1 in the promoter region may be a partial driver of PAH in later life.

NADPH oxidase in the vasculature: Expression, regulation and signalling pathways; role in normal cardiovascular physiology and its dysregulation in hypertension

The last 20-25 years have seen an explosion of interest in the role of NADPH oxidase (NOX) in cardiovascular function and disease. In vascular smooth muscle and endothelium, NOX generates reactive oxygen species (ROS) that act as second messengers, contributing to the control of normal vascular function. NOX activity is altered in response to a variety of stimuli, including G-protein coupled receptor agonists, growth-factors, perfusion pressure, flow and hypoxia. NOX-derived ROS are involved in smooth muscle constriction, endothelium-dependent relaxation and smooth muscle growth, proliferation and migration, thus contributing to the fine-tuning of blood flow, arterial wall thickness and vascular resistance. Through reversible oxidative modification of target proteins, ROS regulate the activity of protein tyrosine phosphatases, kinases, G proteins, ion channels, cytoskeletal proteins and transcription factors. There is now considerable, but somewhat contradictory evidence that NOX contributes to the pathogenesis of hypertension through oxidative stress. Specific NOX isoforms have been implicated in endothelial dysfunction, hyper-contractility and vascular remodelling in various animal models of hypertension, pulmonary hypertension and pulmonary arterial hypertension, but also have potential protective effects, particularly NOX4. This review explores the multiplicity of NOX function in the healthy vasculature and the evidence for and against targeting NOX for antihypertensive therapy.

Proteomics analysis of fetal growth restriction and taurine‑treated fetal growth restriction rat brain tissue by 2D DIGE and MALDI‑TOF/TOF MS analysis

Fetal growth restriction (FGR) is caused by placental insufficiency and can lead to short and long‑term neurodevelopmental delays. Taurine, one of the most abundant amino acids in the brain, is critical for the normal growth and development of the nervous system; however, the mechanistic role of taurine in neural growth and development remains unknown. The present study investigated the role of taurine in FGR. Specifically, we explored the proteomic profiles of fetal rats at 6 h postpartum by two‑dimensional difference gel electrophoresis combined with matrix assisted laser desorption ionization‑time‑of‑flight (TOF)/TOF tandem mass spectrometry; the findings were verified via reverse transcription‑quantitative polymerase chain reaction. A total of 31 differentially expressed protein spots were selected. Among these, 31 were matched, including dihydropyrimidinase‑related protein 2 and , CRK and peroxiredoxin 2. Functional analysis using the Gene Ontology database and Ingenuity Pathway Analysis demonstrated that the differentially expressed proteins were mainly associated with neuronal differentiation, 'metabolic process', 'biological regulation' and developmental processes. The present study identified several proteins that were differentially expressed in rats with FGR in the presence or absence of taurine administration. The results of the present study suggest a potential role for taurine in the treatment and prevention of FGR.

The LKB1-AMPK-α1 signaling pathway triggers hypoxic pulmonary vasoconstriction downstream of mitochondria

Hypoxic pulmonary vasoconstriction (HPV), which aids ventilation-perfusion matching in the lungs, is triggered by mechanisms intrinsic to pulmonary arterial smooth muscles. The unique sensitivity of these muscles to hypoxia is conferred by mitochondrial cytochrome c oxidase subunit 4 isoform 2, the inhibition of which has been proposed to trigger HPV through increased generation of mitochondrial reactive oxygen species. Contrary to this model, we have shown that the LKB1-AMPK-α1 signaling pathway is critical to HPV. Spectral Doppler ultrasound revealed that deletion of the AMPK-α1 catalytic subunit blocked HPV in mice during mild (8% O₂) and severe (5% O₂) hypoxia, whereas AMPK-α2 deletion attenuated HPV only during severe hypoxia. By contrast, neither of these genetic manipulations affected serotonin-induced reductions in pulmonary vascular flow. HPV was also attenuated by reduced expression of LKB1, a kinase that activates AMPK during energy stress, but not after deletion of CaMKK2, a kinase that activates AMPK in response to increases in cytoplasmic Ca²⁺ Fluorescence imaging of acutely isolated pulmonary arterial myocytes revealed that AMPK-α1 or AMPK-α2 deletion did not affect mitochondrial membrane potential during normoxia or hypoxia. However, deletion of AMPK-α1, but not of AMPK-α2, blocked hypoxia from inhibiting K_V1.5, the classical "oxygen-sensing" K⁺ channel in pulmonary arterial myocytes. We conclude that LKB1-AMPK-α1 signaling pathways downstream of mitochondria are critical for the induction of HPV, in a manner also supported by AMPK-α2 during severe hypoxia.

Change of voltage-gated potassium channel 1.7 expressions in monocrotaline-induced pulmonary arterial hypertension rat model

Purpose

Abnormal potassium channels expression affects vessel function, including vascular tone and proliferation rate. Diverse potassium channels, including voltage-gated potassium (Kv) channels, are involved in pathological changes of pulmonary arterial hypertension (PAH). Since the role of the Kv1.7 channel in PAH has not been previously studied, we investigated whether Kv1.7 channel expression changes in the lung tissue of a monocrotaline (MCT)-induced PAH rat model and whether this change is influenced by the endothelin (ET)-1 and reactive oxygen species (ROS) pathways.

Methods

Rats were separated into 2 groups: the control (C) group and the MCT (M) group (60 mg/kg MCT). A hemodynamic study was performed by catheterization into the external jugular vein to estimate the right ventricular pressure (RVP), and pathological changes in the lung tissue were investigated. Changes in protein and mRNA levels were confirmed by western blot and polymerase chain reaction analysis, respectively.

Results

MCT caused increased RVP, medial wall thickening of the pulmonary arterioles, and increased expression level of ET-1, ET receptor A, and NADPH oxidase (NOX) 4 proteins. Decreased Kv1.7 channel expression was detected in the lung tissue. Inward-rectifier channel 6.1 expression in the lung tissue also increased. We confirmed that ET-1 increased NOX4 level and decreased glutathione peroxidase-1 level in pulmonary artery smooth muscle cells (PASMCs). ET-1 increased ROS level in PASMCs.

Conclusion

Decreased Kv1.7 channel expression might be caused by the ET-1 and ROS pathways and contributes to MCT-induced PAH.