GSK3β inhibition and canonical Wnt signaling in mice hearts after myocardial ischemic damage

Unique Splicing of Lrp5 in the Brain: A New Player in Neurodevelopment and Brain Maturation

Low-density lipoprotein receptor-related protein 5 (LRP5) is a constitutively expressed receptor with observed roles in bone homeostasis, retinal development, and cardiac metabolism. However, the function of LRP5 in the brain remains unexplored. This study investigates LRP5's role in the central nervous system by conducting an extensive analysis using RNA-seq tools and in silico assessments. Two protein-coding Lrp5 transcripts are expressed in mice: full-length Lrp5-201 and a truncated form encoded by Lrp5-202. Wt mice express Lrp5-201 in the liver and brain and do not express the truncated form. Lrp5-/- mice express Lrp5-202 in the liver and brain and do not express Lrp5-201 in the liver. Interestingly, Lrp5-/- mouse brains show full-length Lrp5-201 expression, suggesting that LRP5 has a role in preserving brain function during development. Functional gene enrichment analysis on RNA-seq unveils dysregulated expression of genes associated with neuronal differentiation and synapse formation in the brains of Lrp5-/- mice compared to Wt mice. Furthermore, Gene Set Enrichment Analysis highlights downregulated expression of genes involved in retinol and linoleic acid metabolism in Lrp5-/- mouse brains. Tissue-specific alternative splicing of Lrp5 in Lrp5-/- mice supports that the expression of LRP5 in the brain is needed for the correct synthesis of vitamins and fatty acids, and it is indispensable for correct brain development.

Canonical Wnt activator Chir99021 prevents epileptogenesis in the intrahippocampal kainate mouse model of temporal lobe epilepsy

The Wnt signaling pathway mediates the development of dentate granule cell neurons in the hippocampus. These neurons are central to the development of temporal lobe epilepsy and undergo structural and physiological remodeling during epileptogenesis, which results in the formation of epileptic circuits. The pathways responsible for granule cell remodeling during epileptogenesis have yet to be well defined, and represent therapeutic targets for the prevention of epilepsy. The current study explores Wnt signaling during epileptogenesis and for the first time describes the effect of Wnt activation using Wnt activator Chir99021 as a novel anti-epileptogenic therapeutic approach. Focal mesial temporal lobe epilepsy was induced by intrahippocampal kainate (IHK) injection in wild-type and POMC-eGFP transgenic mice. Wnt activator Chir99021 was administered daily, beginning 3 h after seizure induction, and continued up to 21-days. Immature granule cell morphology was quantified in the ipsilateral epileptogenic zone and the contralateral peri-ictal zone 14 days after IHK, targeting the end of the latent period. Bilateral hippocampal electrocorticographic recordings were performed for 28-days, 7-days beyond treatment cessation. Hippocampal behavioral tests were performed after completion of Chir99021 treatment. Consistent with previous studies, IHK resulted in the development of epilepsy after a 14 day latent period in this well-described mouse model. Activation of the canonical Wnt pathway with Chir99021 significantly reduced bilateral hippocampal seizure number and duration. Critically, this effect was retained after treatment cessation, suggesting a durable antiepileptogenic change in epileptic circuitry. Morphological analyses demonstrated that Wnt activation prevented pathological remodeling of the primary dendrite in both the epileptogenic zone and peri-ictal zone, changes in which may serve as a biomarker of epileptogenesis and anti-epileptogenic treatment response in pre-clinical studies. These findings were associated with improved object location memory with Chir99021 treatment after IHK. This study provides novel evidence that canonical Wnt activation prevents epileptogenesis in the IHK mouse model of mesial temporal lobe epilepsy, preventing pathological remodeling of dentate granule cells. Wnt signaling may therefore play a key role in mesial temporal lobe epileptogenesis, and Wnt modulation may represent a novel therapeutic strategy in the prevention of epilepsy.

Canonical Wnt pathway and the LDL receptor superfamily in neuronal cholesterol homeostasis and function

AIMS

There is little information on the regulation of cholesterol homeostasis in the brain. Whether cholesterol crosses the blood-brain barrier is under investigation, but the present understanding is that cholesterol metabolism in the brain is independent from that in peripheral tissues. Lipoprotein receptors from the LDL receptor family (LRPs) have key roles in lipid particle accumulation in cells involved in vascular and cardiac pathophysiology; however, their function on neural cells is unknown.

METHODS AND RESULTS

The expression of LRP5 and the components and targets of its downstream signalling pathway, the canonical Wnt pathway, including β-catenin, LEF1, VEGF, OPN, MMP7, and ADAM10, is analysed in the brains of Wt and Lrp5-/- mice and in a neuroblastoma cell line. LRP5 expression is increased in a time- and dose-dependent manner after lipid loading in neuronal cells; however, it does not participate in cholesterol homeostasis as shown by intracellular lipid accumulation analyses. Neurons challenged with staurosporin and H2O2 display an anti-apoptotic protective role for LRP5.

CONCLUSIONS

For the first time, it has been shown that neurons can accumulate intracellular lipids and lipid uptake is performed mainly by the LDLR, while CD36, LRP1, and LRP5 do not play a major role. In addition, it has been shown that LRP5 triggers the canonical Wnt pathway in neuronal cells to generate pro-survival signals. Finally, Lrp5-/- mice have maintained expression of LRP5 only in the brain supporting the biological plausible concept of the need of brain LRP5 to elicit pro-survival processes and embryonic viability.

CHIR99021 causes inactivation of Tyrosine Hydroxylase and depletion of dopamine in rat brain striatum

CHIR99021, also known as laduviglusib or CT99021, is a Glycogen-synthase kinase 3β (GSK3β) inhibitor, which has been reported as a promising drug for cardiomyocyte regeneration or treatment of sensorial hearing loss. Since the activation of dopamine (DA) receptors regulates dopamine synthesis and they can signal through the β-arrestin pathway and GSK3β, we decided to check the effect of GSK3β inhibitors (CHIR99021, SB216763 and lithium ion) on the control of DA synthesis. Using ex vivo experiments with minces from rat brain striatum, we observed that CHIR99021, but not SB216763 or lithium, causes complete abrogation of both DA synthesis and accumulation, pointing to off-target effects of CHIR99021. This decrease can be attributed to tyrosine hydroxylase (TH) inhibition since the accumulation of l-DOPA in the presence of a DOPA decarboxylase inhibitor was similarly decreased. On the other hand, CHIR99021 caused a dramatic increase in the DOPAC/DA ratio, an indicator of DA metabolization, and hindered DA incorporation into striatum tissue. Tetrabenazine, an inhibitor of DA vesicular transport, also caused DA depletion and DOPAC/DA ratio increase to the same extent as CHIR99021. In addition, both CHIR99021 or SB216763, but not lithium, decreased TH phosphorylation in Ser19, but not in Ser31 or Ser40. These results demonstrate that CHIR99021 can lead to TH inactivation and DA depletion in brain striatum, opening the possibility of its use in DA-related disorders, and shows effects to be considered in future clinical trials. More work is needed to find the mechanism exerted by CHIR99021 on DA accumulation.

Mechanistic study on ursolic acid inhibiting the growth of colorectal cancer cells through the downregulation of TGF-β3 by miR-140-5p

Colorectal cancer (CRC) is a common digestive tract tumor with a high incidence and a poor prognosis. Traditional chemotherapy drugs are usually accompanied by unpleasant side effects, highlighting the importance of exploring new adjunctive drugs. In this study, we aimed to explore the role of ursolic acid (UA) in CRC cells. Specifically, HT-29 cells were treated with UA at different concentrations (10, 20, 30, and 40 μM), and the expression of miR-140-5p, tumor growth factor-β3 (TGF-β3), β-catenin, and cyclin D1 was determined by real-time quantitative PCR. The cell cycle and apoptosis were checked by flow cytometry, and cell proliferation was detected by Cell Counting Kit-8 assay. The HT-29 cell model was established through overexpression (miR-140-5p mimics) and interference (miR-140-5p inhibitor) of miR-140-5p. Western blot was used to detect the protein expression of TGF-β3. We found that UA could inhibit the proliferation of HT-29 cells, block cells in the G1 phase, and promote cell apoptosis. After UA treatment, the expression of miR-140-5p increased and TGF-β3 decreased. Notably, miR-140-5p downregulated the expression of TGF-β3, while the overexpression of miR-140-5p exerted a similar function to UA in HT-29 cells. Additionally, the messenger RNA expression of TGF-β3, β-catenin, and cyclin D1 was decreased in HT-29 cells after UA treatment. In conclusion, UA inhibited CRC cell proliferation and cell cycle and promoted apoptosis by regulating the miR-140-5p/TGF-β3 axis, which may be related to the inhibition of Wnt/β-catenin signaling pathway.

CREB-binding protein and HIF-1α/β-catenin to upregulate miR-322 and alleviate myocardial ischemia-reperfusion injury

Myocardial ischemia/reperfusion injury (MIRI) is a prevalent condition associated with numerous critical clinical conditions. miR-322 has been implicated in MIRI through poorly understood mechanisms. Our preliminary analysis indicated potential interaction of CREB-binding protein (CBP), a transcriptional coactivator and acetyltransferase, with HIF-1α/β-catenin, which might regulate miR-322 expression. We, therefore, hypothesized that CBP/HIF-1α/β-catenin/miR-322 axis might play a role in MIRI. Rat cardiomyocytes subjected to oxygen-glucose deprivation /reperfusion (OGD/R) and Langendorff perfused heart model were used to model MIRI in vitro and in vivo, respectively. We used various techniques such as CCK-8 assay, transferase dUTP nick end labeling staining, western blotting, RT-qPCR, chromatin immunoprecipitation (ChIP), dual-luciferase assay, co-immunoprecipitation (Co-IP), hematoxylin and eosin staining, and TTC staining to assess cell viability, apoptosis, and the levels of CBP, HIF-1α, β-catenin, miR-322, and acetylation. Our results indicate that OGD/R in cardiomyocytes decreased CBP/HIF-1α/β-catenin/miR-322 expression, increased cell apoptosis and cytokines, and reduced cell viability. However, overexpression of CBP or miR-322 suppressed OGD/R-induced cell injury, while knockdown of HIF-1α/β-catenin further exacerbated the damage. HIF-1α/β-catenin bound to miR-322 promoter to promote its expression, while CBP acetylated HIF-1α/β-catenin for stabilization. Overexpression of CBP attenuated MIRI in rats by acetylating HIF-1α/β-catenin to stabilize their expression, resulting in stronger binding of HIF-1α/β-catenin with the miR-322 promoter and subsequent increased miR-322 levels. Therefore, activating CBP/HIF-1α/β-catenin/miR-322 signaling may be a potential approach to treat MIRI.

PM2.5-Induced Cardiac Structural Modifications and Declined Pro-Survival Signalling Pathways Are Responsible for the Inefficiency of GSK-3β Inhibitor in Attenuating Myocardial Ischemia-Reperfusion Injury in Rats

Circulatory GSK3β is recognized as a biomarker and therapeutic target for diseases, including myocardial diseases. However, its potential as a target for myocardial ischemia-reperfusion injury (IR) in the presence of PM2.5 exposure is unclear. Wistar rats underwent IR following either a 21-day or single exposure to PM2.5 at a concentration of 250 µg/m3. The effects of GSK3β inhibitor on cardiac physiology, tissue injury, mitochondrial function, and the PI3K/AKT/GSK3β signalling axis were examined. The inhibitor was not effective in improving hemodynamics or reducing IR-induced infarction in the myocardium exposed to PM2.5 for 21 days. However, for a single-day exposure, the inhibitor showed potential in mitigating cardiac injury. In normal hearts undergoing IR, the inhibitor activated the PI3K/AKT signalling pathway, improved mitochondrial function, and reduced oxidative stress. These positive effects were not observed in PM2.5-exposed rats. Furthermore, the inhibitor stimulated autophagy in hearts exposed to PM2.5 for 21 days and subjected to IR, resulting in increased mTOR expression and decreased AMPK expression. In normal hearts and those exposed to a single dose of PM2.5, the inhibitor effectively activated the PI3K/Akt/AMPK axis. These findings suggest that GSK3β may not be a reliable therapeutic target for IR in the presence of chronic PM2.5 exposure.

GSK3β inhibitor TDZD8 ameliorates brain damage through both ROS scavenging and inhibition of apoptosis in hyperglycaemic subarachnoid haemorrhage rats

Hyperglycaemia is known to be associated with unfavourable outcomes in subarachnoid haemorrhage (SAH), but the pathogenic mechanism is unclear, and there is also a lack of effective therapeutic drugs in clinical practice. Phosphorylation of GSK3β at serine 9 can inhibit its activity to further worsen SAH. The aim of the present study was to evaluate the protective effect and the potential mechanism of the GSK3β inhibitor TDZD8 on brain injury in a hyperglycaemic SAH rat model. Hyperglycaemia was induced by intraperitoneal injection of streptozocin for 3 days. The SAH model was established by injecting fresh autologous femoral artery blood into the prechiasmatic cistern. p-GSK3β (Ser9) expression was induced by intraperitoneal injection of TDZD8 (30 min post-SAH). The expression levels of GSK3β, p-GSK3β, SOD1/2, caspase 3, Bax and Bcl-2 were detected by western blot analysis. Terminal deoxynucleotidyl transferase dUTP nick end-labelling (TUNEL) staining was used to detect neuronal apoptosis of basal temporal lobe. Neurological scores were calculated to determine behavioural recovery. Neuronal survival was detected by Nissl staining. Hyperglycaemia significantly decreased p-GSK3β expression, further exacerbated neurobehavioural deficits and increased oxidative stress and neuronal apoptosis in the brain after SAH compared to normal glycaemic SAH rats and hyperglycaemic rats. In addition, hyperglycaemic SAH rats had obvious oxidative stress and apoptosis. However, TDZD8 effectively decreased cleaved caspase 3 expression and TUNEL-positive cells and increased the Bcl2/Bax ratio, expression of SOD1/2 and activity of superoxide dismutase (SOD) enzyme compared with hyperglycaemic SAH rats. The GSK3β inhibitor TDZD8 has therapeutic potential for hyperglycaemic SAH. The neuroprotective effect of TDZD8 appears to be mediated through its antioxidative and antiapoptotic activity.

Wnt Signaling in Heart Development and Regeneration

PURPOSE OF REVIEW

Cardiovascular diseases are the leading cause of death worldwide, largely due to the limited regenerative capacity of the adult human heart. In contrast, teleost zebrafish hearts possess natural regeneration capacity by proliferation of pre-existing cardiomyocytes after injury. Hearts of mice can regenerate if injured in a few days after birth, which coincides with the transient capacity for cardiomyocyte proliferation. This review tends to elaborate the roles and mechanisms of Wnt/β-catenin signaling in heart development and regeneration in mammals and non-mammalian vertebrates.

RECENT FINDINGS

Studies in zebrafish, mice, and human embryonic stem cells demonstrate the binary effect for Wnt/β-catenin signaling during heart development. Both Wnts and Wnt antagonists are induced in multiple cell types during cardiac development and injury repair. In this review, we summarize composites of the Wnt signaling pathway and their different action routes, followed by the discussion of their involvements in cardiac specification, proliferation, and patterning. We provide overviews about canonical and non-canonical Wnt activity during heart homeostasis, remodeling, and regeneration. Wnt/β-catenin signaling exhibits biphasic and antagonistic effects on cardiac specification and differentiation depending on the stage of embryogenesis. Inhibition of Wnt signaling is beneficial for cardiac wound healing and functional recovery after injury. Understanding of the roles and mechanisms of Wnt signaling pathway in injured animal hearts will contribute to the development of potential therapeutics for human diseased hearts.

Defining the molecular underpinnings controlling cardiomyocyte proliferation

Shortly after birth, mammalian cardiomyocytes (CM) exit the cell cycle and cease to proliferate. The inability of adult CM to replicate renders the heart particularly vulnerable to injury. Restoration of CM proliferation would be an attractive clinical target for regenerative therapies that can preserve contractile function and thus prevent the development of heart failure. Our review focuses on recent progress in understanding the tight regulation of signaling pathways and their downstream molecular mechanisms that underly the inability of CM to proliferate in vivo. In this review, we describe the temporal expression of cell cycle activators e.g., cyclin/Cdk complexes and their inhibitors including p16, p21, p27 and members of the retinoblastoma gene family during gestation and postnatal life. The differential impact of members of the E2f transcription factor family and microRNAs on the regulation of positive and negative cell cycle factors is discussed. This review also highlights seminal studies that identified the coordination of signaling mechanisms that can potently activate CM cell cycle re-entry including the Wnt/Ctnnb1, Hippo, Pi3K-Akt and Nrg1-Erbb2/4 pathways. We also present an up-to-date account of landmark studies analyzing the effect of various genes such as Argin, Dystrophin, Fstl1, Meis1, Pitx2 and Pkm2 that are responsible for either inhibition or activation of CM cell division. All these reports describe bona fide therapeutically targets that could guide future clinical studies toward cardiac repair.

Bacteria-Mediated Oncogenesis and the Underlying Molecular Intricacies: What We Know So Far

Cancers are known to have multifactorial etiology. Certain bacteria and viruses are proven carcinogens. Lately, there has been in-depth research investigating carcinogenic capabilities of some bacteria. Reports indicate that chronic inflammation and harmful bacterial metabolites to be strong promoters of neoplasticity. Helicobacter pylori-induced gastric adenocarcinoma is the best illustration of the chronic inflammation paradigm of oncogenesis. Chronic inflammation, which produces excessive reactive oxygen species (ROS) is hypothesized to cause cancerous cell proliferation. Other possible bacteria-dependent mechanisms and virulence factors have also been suspected of playing a vital role in the bacteria-induced-cancer(s). Numerous attempts have been made to explore and establish the possible relationship between the two. With the growing concerns on anti-microbial resistance and over-dependence of mankind on antibiotics to treat bacterial infections, it must be deemed critical to understand and identify carcinogenic bacteria, to establish their role in causing cancer.

Differential cholesterol uptake in liver cells: A role for PCSK9

The clearance of low-density lipoprotein (LDL) particles from the circulation is regulated by the LDL receptor (LDLR) and proprotein convertase subtilisin/kexin 9 (PCSK9) interaction. Its disruption reduces blood cholesterol levels and delays atherosclerosis progression. Whether other members of the LDLR superfamily are in vivo targets of PCSK9 has been poorly explored. The aim of this work was to study the interaction between PCSK9 and members of the LDLR superfamily in the regulation of liver cholesterol homeostasis in an in vivo low-density lipoprotein receptor related protein 5 (LRP5) deficient mice model challenged with high-fat diet. Our results show that Wt and Lrp5^-/- mice fed a hypercholesterolemic diet (HC) have increased cholesterol ester accumulation and decreased liver LDLR and LRP5 gene and protein expression. Very low-density lipoprotein receptor (VLDLR), LRP6, LRP2, and LRP1 expression levels were analyzed in liver samples and show that they do not participate in Lrp5^-/- liver cholesterol uptake. Immunoprecipitation experiments show that LRP5 forms a complex with PCSK9 in liver-specific fat-storing stellate cells but not in structural HepG2 cells. Hepatic stellate cells silenced for LRP5 and/or PCSK9 expression and challenged with lipids show reduced cholesterol ester accumulation, indicating that both proteins are involved in lipid processing in the liver. Our results indicate that cholesterol esters accumulate in livers of Wt mice in a LDLR-family-members dependent manner as VLDLR, LRP2, and LRP6 show increased expression in HC mice. However, this increase is lost in livers of Lrp5^-/- mice, where scavenger receptors are involved in cholesterol uptake. PCSK9 expression is strongly downregulated in mice livers after HC feeding. However PCSK9 and LRP5 bind in the cytoplasm of fat storing liver cells, indicating that this PCSK9-LRP5 interaction is cell-type specific and that both proteins contribute to lipid uptake.

Preconditioning the rat heart with 5-azacytidine attenuates myocardial ischemia/reperfusion injury via PI3K/GSK3β and mitochondrial KATP signaling axis

5-Azacytidine is well known for its clinical usage in cancer treatments. The present study investigates the role of 5-azacytidine as a cardioprotective agent to ameliorate ischemia/reperfusion (I/R) injury. The cardioprotective effect of 5-azacytidine was evaluated in three experimental models: in vitro, ex vivo, and in vivo. The cardioprotective effect was evaluated via cell viability, hemodynamic indices, infarct size measurement, and assessment of histopathology, oxidative stress, and mitochondrial function. The experiments were repeated in the presence of PI3K/GSK3β and mitochondrial K_ATP (mtK_ATP ) cardioprotective signaling pathway inhibitors to understand the underlying mechanism. 5-Azacytidine improved the cell viability by 29% in I/R-challenged H9C2 cells. Both isolated rat heart and LAD ligation model confirmed the infarct sparing effect of 5-azacytidine against I/R. It also provided a beneficial effect by normalizing the altered hemodynamics, reducing the infarct size and cardiac injury markers, reversing the perturbation of mitochondria, reduced oxidative stress, and improved the pPI3K and pAKT protein expression from I/R. In addition, it also augmented the activation of PI3K/AKT and mtK_ATP signaling pathway, confirmed by using wortmannin (PI3K inhibitor), SB216763 (GSK3β inhibitor), and glibenclamide (mtK_ATP channel closer). The effectiveness of 5-azacytidine as a cardioprotective agent is attributed to its activation of the PI3K/GSK3β and mtK_ATP channel signaling axis, thereby preserving mitochondrial function and reducing oxidative stress.

Microvesicles carrying LRP5 induce macrophage polarization to an anti-inflammatory phenotype

Microvesicles (MV) contribute to cell-to-cell communication through their transported proteins and nucleic acids. MV, released into the extracellular space, exert paracrine regulation by modulating cellular responses after interaction with near and far target cells. MV are released at high concentrations by activated inflammatory cells. Different subtypes of human macrophages have been characterized based on surface epitopes being CD16+ macrophages associated with anti-inflammatory phenotypes. We have previously shown that low-density lipoprotein receptor-related protein 5 (LRP5), a member of the LDLR family that participates in lipid homeostasis, is expressed in macrophage CD16+ with repair and survival functions. The goal of our study was to characterize the cargo and tentative function of macrophage-derived MV, whether LRP5 is delivered into MV and whether these MV are able to induce inflammatory cell differentiation to a specific CD16- or CD16+ phenotype. We show, for the first time, that lipid-loaded macrophages release MV containing LRP5. LDL loading induces increased expression of macrophage pro-inflammatory markers and increased release of MV containing pro-inflammatory markers. Conditioning of fresh macrophages with MV released by Lrp5-silenced macrophages induced the transcription of inflammatory genes and reduced the transcription of anti-inflammatory genes. Thus, MV containing LRP5 induce anti-inflammatory phenotypes in macrophages.

The Potential Role of Inflammation in Modulating Endogenous Hippocampal Neurogenesis After Spinal Cord Injury

Currently there are approximately 291,000 people suffering from a spinal cord injury (SCI) in the United States. SCI is associated with traumatic changes in mobility and neuralgia, as well as many other long-term chronic health complications, including metabolic disorders, diabetes mellitus, non-alcoholic steatohepatitis, osteoporosis, and elevated inflammatory markers. Due to medical advances, patients with SCI survive much longer than previously. This increase in life expectancy exposes them to novel neurological complications such as memory loss, cognitive decline, depression, and Alzheimer's disease. In fact, these usually age-associated disorders are more prevalent in people living with SCI. A common factor of these disorders is the reduction in hippocampal neurogenesis. Inflammation, which is elevated after SCI, plays a major role in modulating hippocampal neurogenesis. While there is no clear consensus on the mechanism of the decline in hippocampal neurogenesis and cognition after SCI, we will examine in this review how SCI-induced inflammation could modulate hippocampal neurogenesis and provoke age-associated neurological disorders. Thereafter, we will discuss possible therapeutic options which may mitigate the influence of SCI associated complications on hippocampal neurogenesis.

Effect of Interventions in WNT Signaling on Healing of Cardiac Injury: A Systematic Review

The wound healing that follows myocardial infarction is a complex process involving multiple mechanisms, such as inflammation, angiogenesis and fibrosis. In the last two decades, the involvement of WNT signaling has been extensively studied and effects on virtually all aspects of this wound healing have been reported. However, as often is the case in a newly emerging field, inconsistent and sometimes even contradictory findings have been reported. The aim of this systematic review is to provide a comprehensive overview of studies in which the effect of interventions in WNT signaling were investigated in in vivo models of cardiac injury. To this end, we used different search engines to perform a systematic search of the literature using the key words "WNT and myocardial and infarction". We categorized the interventions according to their place in the WNT signaling pathway (ligand, receptor, destruction complex or nuclear level). The most consistent improvements of the wound healing response were observed in studies in which the acylation of WNT proteins was inhibited by administering porcupine inhibitors, by inhibiting of the downstream glycogen synthase kinase-3β (GSK3β) and by intervening in the β-catenin-mediated gene transcription. Interestingly, in several of these studies, evidence was presented for activation of cardiomyocyte proliferation around the infarct area. These findings indicate that inhibition of WNT signaling can play a valuable role in the repair of cardiac injury, thereby improving cardiac function and preventing the development of heart failure.

GPX8 is transcriptionally regulated by FOXC1 and promotes the growth of gastric cancer cells through activating the Wnt signaling pathway

BACKGROUND

Glutathione Peroxidase 8 (GPX8) as a member of the glutathione peroxidase (GPx) family plays an important role in anti-oxidation. Besides, dysregulation of GPX8 has been found in gastric cancer, but its detailed molecular mechanism in gastric cancer has not been reported.

METHODS

Our study detected the expression of GPX8 in gastric cancer tissues and cell lines using immunohistochemistry (IHC), western blot and qRT-PCR, and determined the effect of GPX8 on gastric cancer cells using CCK-8, colony formation, transwell migration and invasion assays. Besides, the effect of GPX8 on the Wnt signaling pathway was determined by western blot. Furthermore, the transcription factor of GPX8 was identified by bioinformatics methods, dual luciferase reporter and chromatin immunoprecipitation (CHIP) assays. In addition, the effect of GPX8 on tumor formation was measured by IHC and western blot.

RESULTS

The over-expression of GPX8 was observed in gastric cancer tissues and cells, which facilitated the proliferation, migration and invasion of gastric cancer cells as well as the tumor growth. GPX8 knockdown effectively inhibited the growth of gastric cancer cells and tumors. Moreover, GPX8 could activate the Wnt signaling pathway to promote the cellular proliferation, migration and invasion through. Furthermore, FOXC1 was identified as a transcription factor of GPX8 and mediated GPX8 expression to affect cell development processes.

CONCLUSIONS

These findings contribute to understanding the molecular mechanism of GPX8 in gastric cancer. Additionally, GPX8 can be a potential biomarker for gastric cancer therapy.

Molecular Mechanism of Helicobacter pylori-Induced Gastric Cancer

Introduction

Various types of cancers threaten human life. The role of bacteria in causing cancer is controversial, but it has been determined that the Helicobacter pylori infection is one of the identified risk factors for gastric cancer. Helicobacter pylori infection is highly prevalent, and about half of the world^,s population is infected with it.

Objective

The aim of this study was the role of Helicobacter pylori in the development of gastric cancer.

Method

We obtained information from previously published articles.

Results and Conclusion

The bacterium has various virulence factors, including cytotoxin- associated gene A, vacuolating cytotoxin A, and the different outer membrane proteins that cause cancer by different mechanisms. These virulence factors activate cell signaling pathways such as PI3-kinase/Akt, JAK/STAT and Ras, Raf, and ERK signaling that control cell proliferation. Uncontrolled proliferation can lead to cancer.

The effect of nutraceuticals on multiple signaling pathways in cardiac fibrosis injury and repair

Cardiac fibrosis is one of the most common pathological conditions caused by different heart diseases, including myocardial infarction and diabetic cardiomyopathy. Cardiovascular disease is one of the major causes of mortality worldwide. Cardiac fibrosis is caused by different processes, including inflammatory reactions and oxidative stress. The process of fibrosis begins by changing the balance between production and destruction of extracellular matrix components and stimulating the proliferation and differentiation of cardiac fibroblasts. Many studies have focused on finding drugs with less adverse effects for the treatment of cardiovascular disease. Some studies show that nutraceuticals are effective in preventing and treating diseases, including cardiovascular disease, and that they can reduce the risk. However, big clinical studies to prove the therapeutic properties of all these substances and their adverse effects are lacking so far. Therefore, in this review, we tried to summarize the knowledge on pathways and mechanisms of several nutraceuticals which have shown their usefulness in the prevention of cardiac fibrosis.

Interventions in WNT Signaling to Induce Cardiomyocyte Proliferation: Crosstalk with Other Pathways

Myocardial infarction is a frequent cardiovascular event and a major cause for cardiomyocyte loss. In adult mammals, cardiomyocytes are traditionally considered to be terminally differentiated cells, unable to proliferate. Therefore, the wound-healing response in the infarct area typically yields scar tissue rather than newly formed cardiomyocytes. In the last decade, several lines of evidence have challenged the lack of proliferative capacity of the differentiated cardiomyocyte: studies in zebrafish and neonatal mammals have convincingly demonstrated the regenerative capacity of cardiomyocytes. Moreover, multiple signaling pathways have been identified in these models that-when activated in adult mammalian cardiomyocytes-can reactivate the cell cycle in these cells. However, cardiomyocytes frequently exit the cell cycle before symmetric division into daughter cells, leading to polyploidy and multinucleation. Now that there is more insight into the reactivation of the cell cycle machinery, other prerequisites for successful symmetric division of cardiomyocytes, such as the control of sarcomere disassembly to allow cytokinesis, require more investigation. This review aims to discuss the signaling pathways involved in cardiomyocyte proliferation, with a specific focus on wingless/int-1 protein signaling. Comparing the conflicting results from in vitro and in vivo studies on this pathway illustrates that the interaction with other cells and structures around the infarct is likely to be essential to determine the outcome of these interventions. The extensive crosstalk with other pathways implicated in cardiomyocyte proliferation calls for the identification of nodal points in the cell signaling before cardiomyocyte proliferation can be moved forward toward clinical application as a cure of cardiac disease. SIGNIFICANCE STATEMENT: Evidence is mounting that proliferation of pre-existing cardiomyocytes can be stimulated to repair injury of the heart. In this review article, an overview is provided of the different signaling pathways implicated in cardiomyocyte proliferation with emphasis on wingless/int-1 protein signaling, crosstalk between the pathways, and controversial results obtained in vitro and in vivo.