A static pressure sensitive receptor APJ promote H9c2 cardiomyocyte hypertrophy via PI3K-autophagy pathway

The role of endothelial cell in cardiac hypertrophy: Focusing on angiogenesis and intercellular crosstalk

Cardiac hypertrophy is characterized by cardiac structural remodeling, fibrosis, microvascular rarefaction, and chronic inflammation. The heart is structurally organized by different cell types, including cardiomyocytes, fibroblasts, endothelial cells, and immune cells. These cells highly interact with each other by a number of paracrine or autocrine factors. Cell-cell communication is indispensable for cardiac development, but also plays a vital role in regulating cardiac response to damage. Although cardiomyocytes and fibroblasts are deemed as key regulators of hypertrophic stimulation, other cells, including endothelial cells, also exert important effects on cardiac hypertrophy. More particularly, endothelial cells are the most abundant cells in the heart, which make up the basic structure of blood vessels and are widespread around other cells in the heart, implicating the great and inbuilt advantage of intercellular crosstalk. Cardiac microvascular plexuses are essential for transport of liquids, nutrients, molecules and cells within the heart. Meanwhile, endothelial cell-mediated paracrine signals have multiple positive or negative influences on cardiac hypertrophy. However, a comprehensive discussion of these influences and consequences is required. This review aims to summarize the basic function of endothelial cells in angiogenesis, with an emphasis on angiogenic molecules under hypertrophic conditions. The secondary objective of the research is to fully discuss the key molecules involved in the intercellular crosstalk and the endothelial cell-mediated protective or detrimental effects on other cardiac cells. This review provides a more comprehensive understanding of the overall role of endothelial cells in cardiac hypertrophy and guides the therapeutic approaches and drug development of cardiac hypertrophy.

Apelin/ELABELA-APJ system in cardiac hypertrophy: Regulatory mechanisms and therapeutic potential

Heart failure is one of the most significant public health problems faced by millions of medical researchers worldwide. And pathological cardiac hypertrophy is considered one of the possible factors of increasing the risk of heart failure. Here, we introduce apelin/ELABELA-APJ system as a novel therapeutic target for cardiac hypertrophy, bringing about new directions in clinical treatment. Apelin has been proven to regulate cardiac hypertrophy through various pathways. And an increasing number of studies on ELABELA, the newly discovered endogenous ligand, suggest it can alleviate cardiac hypertrophy through mechanisms similar or different to apelin. In this review, we elaborate on the role that apelin/ELABELA-APJ system plays in cardiac hypertrophy and the intricate mechanisms that apelin/ELABELA-APJ affect cardiac hypertrophy. We also illuminate and make comparisons of the newly designed peptides and small molecules as agonists and antagonists for APJ, updating the breakthroughs in this field.

Elabela: A Novel Biomarker for Right Ventricular Pressure Overload in Children With Pulmonary Stenosis or Pulmonary Atresia With Intact Ventricular Septum

Background: Assessing right ventricular overload in children is challenging. We conducted this study involving children with pulmonary valvular stenosis (PS) or pulmonary atresia with intact ventricular septum (PA/IVS) to evaluate the potential of a new endogenous ligand of apelin receptor, Elabela (ELA), as a potential biomarker for right heart overload.

Methods: In this prospective cohort study, a total of 118 congenital heart diseases patients with right ventricle outflow tract obstruction were recruited from 2018 to 2019. Among them, 44 isolated PS and 7 PA/IVS patients were selected. Their venous blood was collected, and all patients underwent an echocardiographic examination. Among them, post-operative blood was collected from 24 patients with PS after percutaneous balloon pulmonary valvuloplasty. The plasma ELA concentration was measured using enzyme-linked immunosorbent assay.

Results: The ELA was significantly associated with the peak transvalvular pulmonary gradient (r = −0.62; p = 0.02), thus reflecting the severity of PS or PA/IVS. The ELA significantly increased at 3 days after intervention, when mechanical obstruction of the right outflow tract was relieved. Based on the receiver-operator characteristic curve results, ELA could be a risk factor for duct dependence in patients with critical PS or PA/IVS who are younger than 6 months (AUC: 0.82).

Conclusion: ELA concentration and severity of PS or PA/IVS had a significant negative correlation, indicating that ELA might be a novel biomarker for right ventricular afterload and reflect the immediate pressure changes in the right heart. Furthermore, ELA could predict duct-dependency in PS and PA/IVS patients, as valuable as classical echocardiographic indexes.

Stretch-Induced Biased Signaling in Angiotensin II Type 1 and Apelin Receptors for the Mediation of Cardiac Contractility and Hypertrophy

The myocardium has an intrinsic ability to sense and respond to mechanical load in order to adapt to physiological demands. Primary examples are the augmentation of myocardial contractility in response to increased ventricular filling caused by either increased venous return (Frank-Starling law) or aortic resistance to ejection (the Anrep effect). Sustained mechanical overload, however, can induce pathological hypertrophy and dysfunction, resulting in heart failure and arrhythmias. It has been proposed that angiotensin II type 1 receptor (AT1R) and apelin receptor (APJ) are primary upstream actors in this acute myocardial autoregulation as well as the chronic maladaptive signaling program. These receptors are thought to have mechanosensing capacity through activation of intracellular signaling via G proteins and/or the multifunctional transducer protein, β-arrestin. Importantly, ligand and mechanical stimuli can selectively activate different downstream signaling pathways to promote inotropic, cardioprotective or cardiotoxic signaling. Studies to understand how AT1R and APJ integrate ligand and mechanical stimuli to bias downstream signaling are an important and novel area for the discovery of new therapeutics for heart failure. In this review, we provide an up-to-date understanding of AT1R and APJ signaling pathways activated by ligand versus mechanical stimuli, and their effects on inotropy and adaptive/maladaptive hypertrophy. We also discuss the possibility of targeting these signaling pathways for the development of novel heart failure therapeutics.

Hydrostatic pressure suppresses fibrotic changes via Akt/GSK-3 signaling in human cardiac fibroblasts

Mechanical stresses play important roles in the process of constructing and modifying heart structure. It has been well established that stretch force acting on cardiac fibroblasts induces fibrosis. However, the effects of compressive force, that is, hydrostatic pressure (HP), have not been well elucidated. We thus evaluated the effects of HP using a pressure‐loading apparatus in human cardiac fibroblasts (HCFs) in vitro. In this study, high HP (200 mmHg) resulted in significant phosphorylation of Akt in HCFs. HP then greatly inhibited glycogen synthase kinase 3 (GSK‐3)α, which acts downstream of the PI3K/Akt pathway. Similarly, HP suppressed mRNA transcription of inflammatory cytokine‐6, collagen I and III, and matrix metalloproteinase 1, compared with an atmospheric pressure condition. Furthermore, HP inhibited collagen matrix production in a three‐dimensional HCF culture. Taken together, high HP suppressed the differentiation of fibroblasts into the myofibroblast phenotype. HP under certain conditions suppressed cardiac fibrosis via Akt/GSK‐3 signaling in HCFs. These results might help to elucidate the pathology of some types of heart disease.

Cardiac Tissue Chips (CTCs) for Modeling Cardiovascular Disease

OBJECTIVE

Cardiovascular research and regenerative strategies have been significantly limited by the lack of relevant cell culture models that can recreate complex hemodynamic stresses associated with pressure-volume changes in the heart.

METHODS

To address this issue, we designed a biomimetic cardiac tissue chip (CTC) model where encapsulated cardiac cells can be cultured in three-dimensional (3-D) fibres and subjected to hemodynamic loading to mimic pressure-volume changes seen in the left ventricle. These 3-D fibres are suspended within a microfluidic chamber between two posts and integrated within a flow loop. Various parameters associated with heart function, like heart rate, peak-systolic pressure, end-diastolic pressure and volume, end-systolic pressure and volume, and duration ratio between systolic and diastolic, can all be precisely manipulated, allowing culture of cardiac cells under developmental, normal, and disease states.

RESULTS

We describe two examples of how the CTC can significantly impact cardiovascular research by reproducing the pathophysiological mechanical stresses associated with pressure overload and volume overload. Our results using H9c2 cells, a cardiomyogenic cell line, clearly show that culture within the CTC under pathological hemodynamic loads accurately induces morphological and gene expression changes, similar to those seen in both hypertrophic and dilated cardiomyopathy. Under pressure overload, the cells within the CTC see increased hypertrophic remodeling and fibrosis, whereas cells subject to prolonged volume overload experience significant changes to cellular aspect ratio through thinning and elongation of the engineered tissue.

CONCLUSIONS

These results demonstrate that the CTC can be used to create highly relevant models where hemodynamic loading and unloading are accurately reproduced for cardiovascular disease modeling.

Whole transcriptome sequencing reveals biologically significant RNA markers and related regulating biological pathways in cardiomyocyte hypertrophy induced by high glucose

Cardiomyocyte hypertrophy is a physiological adaptation used in an attempt to augment or preserve cardiac function for short periods. Long-term cardiomyocyte hypertrophy often progresses to heart failure. Previous studies have presented comprehensive mechanisms underlying cardiomyocyte hypertrophy, such as signaling pathways, marker genes, and marker miRNAs or lncRNAs. However, the mechanism in RNA level is still unclear. In this study, we used the whole transcriptome technology on cardiomyocety hypertrophy cells, which were cultured with a high concentration of d-glucose. Many differentially expressed markers, including genes, lncRNAs, miRNAs, and circRNAs were identified. Further quantitative real-time PCR verified the highly specific expressed genes, such as Eid1, Timm8b, Mrpl50, Dusp18, Abrc1, Klf13, and Igf1. Moreover, the functional pathways were also enriched with the differentially expressed lncRNA, miRNA, and circRNA. Our study gives new insights into cardiomyocyte hypertrophy and makes great progress in comprehending its mechanism.

Antioxidant N-acetylcysteine inhibits maladaptive myocyte autophagy in pressure overload induced cardiac remodeling in rats

Increased oxidative stress and myocyte autophagy co-exist in cardiac remodeling. However, it is unclear whether oxidative stress mediates maladaptive myocyte autophagy in pathological ventricular remodeling. In this study, we tested the hypothesis that antioxidants prevent maladaptive myocyte autophagy in pressure overload-induced left ventricular (LV) remodeling. Sprague-Dawley rats underwent abdominal aortic constriction (AAC) or sham operation. The animals were randomized to receive an antioxidant N-acetylcysteine (NAC), an autophagy inhibitor 3-methyladenine (3-MA) or placebo treatment for 2 weeks. We measured LV structure and function by echocardiography and hemodynamics, myocyte autophagy and oxidative stress assessed by 8-hydroxy-2-deoxyguanosine (8-OHdG). AAC rats exhibited increased LV hypertrophy assessed by LV wall thickness and myocyte cross-sectional area. NAC prevented LV hypertrophy in AAC rats. There were no significant differences in LV fractional shortening, end-diastolic dimension and the maximal rate of LV pressure rise among the groups. AAC rats showed an increase in myocardial 8-OHdG that was prevented by NAC. The expression of LC3 II protein, a marker of autophagy, was increased at 2 weeks after AAC. Immunohistochemical scores further confirmed the increase in LC3 expression in AAC rats. The expression of autophagic proteins Beclin1 and Atg12 and ERK activity were also increased in AAC rats. NAC prevented the increases in LC3 II protein, LC3 scores, Beclin1, Atg12 and ERK activity in AAC rats. Inhibition of autophagy by 3-MA prevented LV hypertrophy after pressure overload. These findings suggest that antioxidants may be of value to prevent pressure overload-induced cardiac remodeling through inhibition of maladaptive myocyte autophagy.

The Role of Apelin in Cardiovascular Diseases, Obesity and Cancer

Apelin is an endogenous peptide identified as a ligand of the G protein-coupled receptor APJ. Apelin belongs to the family of adipokines, which are bioactive mediators released by adipose tissue. Extensive tissue distribution of apelin and its receptor suggests, that it could be involved in many physiological processes including regulation of blood pressure, body fluid homeostasis, endocrine stress response, cardiac contractility, angiogenesis, and energy metabolism. Additionally, this peptide participates in pathological processes, such as heart failure, obesity, diabetes, and cancer. In this article, we review current knowledge about the role of apelin in organ and tissue pathologies. We also summarize the mechanisms by which apelin and its receptor mediate the regulation of physiological and pathological processes. Moreover, we put forward an indication of apelin as a biomarker predicting cardiac diseases and various types of cancer. A better understanding of the function of apelin and its receptor in pathologies might lead to the development of new medical compounds.

The endoplasmic reticulum stress-autophagy pathway is involved in apelin-13-induced cardiomyocyte hypertrophy in vitro

Apelin is the endogenous ligand for the G protein-coupled receptor APJ, and plays important roles in the cardiovascular system. Our previous studies showed that apelin-13 promotes the hypertrophy of H9c2 rat cardiomyocytes through the PI3K-autophagy pathway. The aim of this study was to explore what roles ER stress and autophagy played in apelin-13-induced hypertrophy of cardiomyocytes in vitro. Treatment of H9c2 cells with apelin-13 (0.001-2 μmol/L) dose-dependently increased the production of ROS and the expression levels of NADPH oxidase 4 (NOX4). Knockdown of Nox4 with siRNAs effectively prevented the reduction of GSH/GSSG ratio in apelin-13-treated cells. Furthermore, apelin-13 treatment dose-dependently increased the expression of Bip and CHOP, two ER stress markers, in the cells. Knockdown of APJ or Nox4 with the corresponding siRNAs, or application of NADPH inhibitor DPI blocked apelin-13-induced increases in Bip and CHOP expression. Moreover, apelin-13 treatment increased the formation of autophagosome and ER fragments and the LC3 puncta in the ER of the cells. Knockdown of APJ, Nox4, Bip or CHOP with the corresponding siRNAs, or application of DPI or salubrinal attenuated apelin-13-induced overexpression of LC3-II/I and beclin 1. Finally, knockdown of Nox4, Bip or CHOP with the corresponding siRNAs, or application of salubrinal significantly suppressed apelin-13-induced increases in the cell diameter, volume and protein contents. Our results demonstrate that ER stress-autophagy is involved in apelin-13-induced H9c2 cell hypertrophy.

Load-dependent effects of apelin on murine cardiomyocytes

The apelin peptide is described as one of the most potent inotropic agents, produced endogenously in a wide range of cells, including cardiomyocytes. Despite positive effects on cardiac contractility in multicellular preparations, as well as indications of cardio-protective actions in several diseases, its effects and mechanisms of action at the cellular level are incompletely understood.

Here, we report apelin effects on dynamic mechanical characteristics of single ventricular cardiomyocytes, isolated from mouse models (control, apelin-deficient [Apelin-KO], apelin-receptor KO mouse [APJ-KO]), and rat. Dynamic changes in maximal velocity of cell shortening and relaxation were monitored. In addition, more traditional indicators of inotropic effects, such as maximum shortening (in mechanically unloaded cells) or peak force development (in auxotonic contracting cells, preloaded using the carbon fibre technique) were studied.

The key finding is that, using Apelin-KO cardiomyocytes exposed to different preloads with the 2-carbon fibre technique, we observe a lowering of the slope of the end-diastolic stress-length relation in response to 10 nM apelin, an effect that is preload-dependent. This suggests a positive lusitropic effect of apelin, which could explain earlier counter-intuitive findings on an apelin-induced increase in contractility occurring without matching rise in oxygen consumption.

Bone morphogenetic protein‑9 promotes the differentiation of mouse spleen macrophages into osteoclasts via the ALK1 receptor and ERK 1/2 pathways in vitro

It has been confirmed that bone morphogenetic protein-9 (BMP-9) promotes the differentiation of osteoblasts. However, the ways in which BMP-9 exerts its effects on the differentiation of osteoclasts and bone resorption remain to be elucidated. The present study was designed to investigate the roles and the molecular mechanism of BMP-9 on the proliferation and differentiation of osteoclast precursors in vitro. Mouse spleen macrophages (RAW 264.7 cells) were cultured in the presence of receptor activator for nuclear factor-κb ligand (RANKL) in vitro. Following treatment with different concentrations of BMP-9, a number of parameters were quantitatively monitored. Cell proliferation was determined using an MTT assay. The expression levels of cell BMP receptor-IA (BMPR-IA), BMPR-IB, BMPR-II and anaplastic lymphoma kinase 1 (ALK1) receptor were detected by ELISA, the small mothers against decapentaplegic pathway, extracellular signal-regulated kinase (ERK)1/2 pathways and markers of osteoclast differentiation were detected by western blotting. The results showed that treatment with BMP-9 alone promoted mouse spleen macrophage proliferation, and the differentiation into osteoclasts occurred only in the presence of RANK. The promoting effect of BMP-9 on cell proliferation and osteoclast differentiation occurred in dose-dependent manner. In addition, BMP-9 significantly upregulated the expression of the ALK1 receptor and inhibited the ERK1/2 pathway. The inhibition of the ERK1/2 pathways was ameliorated by transfection with small interfering (si)RNA ALK1. The effect of BMP-9 on osteoclast differentiation was reduced by transfection with siRNA ALK1, however, the effect was enhanced by the ERK1/2 pathway inhibitor, U0126. The results of the present study demonstrated that BMP-9 promoted the osteoclast differentiation of osteoclast precursors via binding to the ALK1 receptor on the cell surface, and inhibiting the ERK1/2 signaling pathways in the cell.

Apelin/APJ system as a therapeutic target in diabetes and its complications

The G-protein-coupled receptor APJ and its endogenous ligand apelin are widely expressed in many peripheral tissues and central nervous system, including adipose tissue, skeletal muscles and hypothalamus. Apelin/APJ system, involved in numerous physiological functions like angiogenesis, fluid homeostasis and energy metabolism regulation, is notably implicated in the development of different pathologies such as diabetes and its complications. Increasing evidence suggests that apelin regulates insulin sensitivity, stimulates glucose utilization and enhances brown adipogenesis in different tissues associated with diabetes. Moreover, apelin is also involved in the regulation of diabetic complications via binding to APJ receptor. Apelin improves diabetes-induced kidney hypertrophia, normalizes obesity-associated cardiac hypertrophy and negatively promotes retinal angiogenesis in diabetic retinopathy. In this review, we provide a comprehensive overview about the role of apelin/APJ system in different tissues related with diabetes. Furthermore, we describe the pathogenesis of diabetic complications associated with apelin/APJ system. Finally, agonists and antagonists targeted to APJ receptor are described in the literature. Thus, we highlight apelin/APJ system as a novel therapeutic target for pharmacological intervention in treating diabetes and its complications.

The role of autophagy in cardiac hypertrophy

Autophagy is conserved in nature from lower eukaryotes to mammals and is an important self-cannibalizing, degradative process that contributes to the elimination of superfluous materials. Cardiac hypertrophy is primarily characterized by excess protein synthesis, increased cardiomyocyte size, and thickened ventricular walls and is a major risk factor that promotes arrhythmia and heart failure. In recent years, cardiomyocyte autophagy has been considered to play a role in controlling the hypertrophic response. However, the beneficial or aggravating role of cardiomyocyte autophagy in cardiac hypertrophy remains controversial. The exact mechanism of cardiomyocyte autophagy in cardiac hypertrophy requires further study. In this review, we summarize the controversies associated with autophagy in cardiac hypertrophy and provide insights into the role of autophagy in the development of cardiac hypertrophy. We conclude that future studies should emphasize the relationship between autophagy and the different stages of cardiac hypertrophy, as well as the autophagic flux and selective autophagy. Autophagy will be a potential therapeutic target for cardiac hypertrophy.

Endoplasmic reticulum stress: a novel mechanism and therapeutic target for cardiovascular diseases

Endoplasmic reticulum is a principal organelle responsible for folding, post-translational modifications and transport of secretory, luminal and membrane proteins, thus palys an important rale in maintaining cellular homeostasis. Endoplasmic reticulum stress (ERS) is a condition that is accelerated by accumulation of unfolded/misfolded proteins after endoplasmic reticulum environment disturbance, triggered by a variety of physiological and pathological factors, such as nutrient deprivation, altered glycosylation, calcium depletion, oxidative stress, DNA damage and energy disturbance, etc. ERS may initiate the unfolded protein response (UPR) to restore cellular homeostasis or lead to apoptosis. Numerous studies have clarified the link between ERS and cardiovascular diseases. This review focuses on ERS-associated molecular mechanisms that participate in physiological and pathophysiological processes of heart and blood vessels. In addition, a number of drugs that regulate ERS was introduced, which may be used to treat cardiovascular diseases. This review may open new avenues for studying the pathogenesis of cardiovascular diseases and discovering novel drugs targeting ERS.

The mechanosensitive APJ internalization via clathrin-mediated endocytosis: A new molecular mechanism of cardiac hypertrophy

The G protein-coupled receptor APJ elicits cellular response to diverse extracellular stimulus. Accumulating evidence reveals that APJ receptor plays a prominent role in the cardiomyocyte adapting to hypertrophic stimulation. At present, it remains obscure that the regulatory mechanism of APJ receptor in myocardial hypertrophy. The natural endogenous ligands apelin and Elabela as well as agonists maintain high affinity for the APJ receptor and drive its internalization. Ligand-activated receptor internalization is mainly performed by clathrin-mediated endocytic pathway. Simultaneously, clathrin-mediated endocytosis takes participate in the occurrence and development of cardiac hypertrophy. In this study, we hypothesize that natural ligands and agonists induce the mechanosensitive APJ internalization via clathrin-mediated endocytosis. APJ internalization may contribute to the development of cardiac hypertrophy. The mechanosensitive APJ internalization via clathrin-mediated endocytosis may be a new molecular mechanism of cardiac hypertrophy.

Apelin-13 promotes cardiomyocyte hypertrophy via PI3K-Akt-ERK1/2-p70S6K and PI3K-induced autophagy

Apelin is highly expressed in rat left ventricular hypertrophy Sprague Dawley rat models, and it plays a crucial role in the cardiovascular system. The aim this study was to clarify whether apelin-13 promotes hypertrophy in H9c2 rat cardiomyocytes and to investigate its underlying mechanism. The cardiomyocyte hypertrophy was observed by measuring the diameter, volume, and protein content of H9c2 cells. The activation of autophagy was evaluated by observing the morphology of autophagosomes by transmission electron microscopy, observing the subcellular localization of LC3 by light microscopy, and detecting the membrane-associated form of LC3 by western blot analysis. The phosphatidylinositol 3-kinase (PI3K) signaling pathway was identified and the proteins expression was detected using western blot analysis. The results revealed that apelin-13 increased the diameter, volume, and protein content of H9c2 cells and promoted the phosphorylation of PI3K, Akt, ERK1/2, and p70S6K. Apelin-13 activated the PI3K-Akt-ERK1/2-p70S6K pathway. PI3K inhibitor LY294002, Akt inhibitor 1701-1, ERK1/2 inhibitor PD98059 attenuated the increase of the cell diameter, volume, protein content induced by apelin-13. Apelin-13 increased the autophagosomes and up-regulated the expressions of beclin 1 and LC3-II/I both transiently and stably. The autophagy inhibitor 3MA ameliorated the increase of cell diameter, volume, and protein content that were induced by apelin-13. These results suggested that apelin-13 promotes H9c2 rat cardiomyocyte hypertrophy via PI3K-Akt-ERK1/2-p70S6K and PI3K-induced autophagy.

Hypoxia promotes bone marrow-derived mesenchymal stem cell proliferation through apelin/APJ/autophagy pathway

Bone marrow-derived mesenchymal stem cells (BMSCs) are a population of multipotent progenitors that have the capacity of proliferation and differentiation into mesenchymal lineage cells. The regulatory peptide apelin is the endogenous ligand for the G protein-coupled receptor APJ. Apelin, which can enhance BMSC proliferation, has mitogenic effects on a wide variety of cell types. We hypothesized that the increased apelin/APJ might be involved in the occurrence and development of hypoxia-induced BMSC proliferation. BMSCs from the bone marrow of 8- to 10-week-old C57BL/6J mice were cultured under either normoxia (21% oxygen) or hypoxia (1% oxygen) condition. Cell proliferation was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and 5-bromo-2'-deoxyuridine assay. Expressions of hypoxia-inducible factor (HIF)-1α, apelin, APJ, Beclin-1, and LC3II/LC3I were detected by western blot analysis. Results suggested that hypoxia enhanced the proliferation of BMSC in a time-dependent manner. The expressions of HIF-1α, apelin, APJ, Beclin-1, and LC3II/LC3I were increased in BMSCs induced by hypoxia. Small interfering RNA (siRNA)-HIF-1α that inhibited the hypoxia-induced expressions of apelin, APJ, Beclin-1, and LC3II/LC3I prevented hypoxia-induced BMSC proliferation. siRNA-APJ that inhibited the hypoxia-induced expressions of Beclin-1 and LC3II/LC3I reversed hypoxia-induced BMSC proliferation. siRNA-Beclin-1 also abolished hypoxia-induced cell proliferation. These data suggested that the apelin/APJ/autophagy signaling pathway might be involved in hypoxia-induced BMSC proliferation.

Effects of hydraulic pressure on cardiomyoblasts in a microfluidic device

We employed a microfluidic device to study the effects of hydraulic pressure on cardiomyoblast H9c2. The 170 mm Hg pressure increased the cellular area and the expression of atrial natriuretic peptide. With the same device, we demonstrated that the effects of hydraulic pressure on the cardiomyoblast could be reduced by the inhibitor of focal adhesion kinase. This mechanical-chemical antagonism could lead to a potential therapeutic strategy of hypertension-induced cardiac hypertrophy.