NPY Impairs Cell Viability and Mitochondrial Membrane Potential Through Ca2+ and p38 Signaling Pathways in Neonatal Rat Cardiomyocytes

PIN1-mediated ROS production is involved in antagonism of N-acetyl-L-cysteine against arsenic-induced hepatotoxicity

Arsenic, a widely existing environmental contaminant, is recognized to be toxic to multiple organs. Exposure to arsenic results in liver damage via excessive production of reactive oxidative species (ROS). PIN1 regulates the levels of ROS. N-acetyl-L-cysteine (NAC) is an ROS scavenger that protects the hepatic functions. Whether PIN1 plays a regulatory role in NAC-mediated antagonism against arsenic hepatotoxicity remains largely unknown. In our study, the protective effects of NAC against arsenic (NaAsO2)-induced hepatotoxicity were evaluated in vitro and in vivo. Arsenic exposure induced cytotoxicity by increasing the intracellular ROS production, impairing mitochondrial function and inducing apoptosis in L02 hepatocytes. Overexpression of PIN1 markedly protected against arsenic cytotoxicity, decreased ROS levels, and mitigated mitochondrial dysfunction and apoptosis in L02 cells. However, loss of PIN1 further aggravated arsenic-induced cytotoxicity and abolished the protective effects of NAC in L02 cells. An in vivo study showed that pretreatment with NAC rescued arsenic-induced liver injury by restoring liver function and suppressing hepatic oxidative stress. Overexpression of PIN1 in mice transfected with AAV-Pin1 relieved arsenic-induced liver dysfunction and hepatic oxidative stress. Taken together, our study identified PIN1 as a novel intervention target for antagonizing arsenic-induced hepatotoxicity, highlighting a new pharmacological mechanism of NAC targeting PIN1 in antagonism against arsenic toxicity.

Activation of Neuropeptide Y2 Receptor Can Inhibit Global Cerebral Ischemia-Induced Brain Injury

Cardiopulmonary arrest (CA) can greatly impact a patient's life, causing long-term disability and death. Although multi-faceted treatment strategies against CA have improved survival rates, the prognosis of CA remains poor. We previously reported asphyxial cardiac arrest (ACA) can cause excessive activation of the sympathetic nervous system (SNS) in the brain, which contributes to cerebral blood flow (CBF) derangements such as hypoperfusion and, consequently, neurological deficits. Here, we report excessive activation of the SNS can cause enhanced neuropeptide Y levels. In fact, mRNA and protein levels of neuropeptide Y (NPY, a 36-amino acid neuropeptide) in the hippocampus were elevated after ACA-induced SNS activation, resulting in a reduced blood supply to the brain. Post-treatment with peptide YY3-36 (PYY3-36), a pre-synaptic NPY2 receptor agonist, after ACA inhibited NPY release and restored brain circulation. Moreover, PYY3-36 decreased neuroinflammatory cytokines, alleviated mitochondrial dysfunction, and improved neuronal survival and neurological outcomes. Overall, NPY is detrimental during/after ACA, but attenuation of NPY release via PYY3-36 affords neuroprotection. The consequences of PYY3-36 inhibit ACA-induced 1) hypoperfusion, 2) neuroinflammation, 3) mitochondrial dysfunction, 4) neuronal cell death, and 5) neurological deficits. The present study provides novel insights to further our understanding of NPY's role in ischemic brain injury.

Neuropeptide Y and its receptors are expressed in chicken skeletal muscle and regulate mitochondrial function

Neuropeptide Y (NPY) is a highly conserved 36-amino acid neurotransmitter, which is primarily expressed in the mammalian arcuate nucleus of the hypothalamus. It is a potent orexigenic neuropeptide, stimulating appetite and inducing feed intake in a variety of species. Recent research has shown that NPY and its receptors can be expressed by peripheral tissues, but their role is not yet well defined. Specifically, this information is particularly sparse in avian species. Therefore, the aim of this study was to determine the expression of NPY and its receptors, and determine their regulation by environmental and nutritional stressors, in the skeletal muscle of avian species using in vivo and in vitro approaches. Here, we show that NPY and its receptors are expressed in chicken breast and leg muscle as well as in quail myoblast (QM7) cell line. Intraperitoneal injection of recombinant NPY increased feed intake in 9-d old chicks and upregulated the expression of NPY and NPY receptors in breast and leg muscle, suggesting autocrine and/or paracrine roles for NPY. Additionally, NPY is able to modulate the mitochondrial network. In breast muscle, a low dose of NPY upregulated (P < 0.05) the expression of genes involved in ATP production (uncoupling protein, UCP; nuclear factor erythroid 2 like 2, NFE2L2) and dynamics (mitofusin 1, MFN1), while a high dose decreased (P < 0.05) markers of mitochondrial dynamics (mitofusin 2, MFN2; OPA1 mitochondrial dynamin like GTPase, OPA1) and increased (P < 0.05) genes involved in mitochondrial biogenesis (D-loop, peroxisome proliferator activated receptor gamma, PPARG). In leg muscle, NPY decreased (P < 0.05) markers of mitochondrial biogenesis and ATP synthesis (D-loop; peroxisome proliferator activated receptor alpha, PCG1A; peroxisome proliferator-activated receptor gamma, coactivator 1 beta, PPARGC1B; PPARG; NFE2L2). In QM7 cells, genes associated with mitochondrial biogenesis, dynamics, and ATP synthesis were all upregulated (P < 0.05), even though basal respiration and ATP production were decreased (P < 0.05) with NPY treatment as measured by XF Flux analysis. Together, these data show that the NPY system is expressed in avian skeletal muscle and plays a role in mitochondrial function.

Neuropeptide Y Induces Cardiomyocyte Hypertrophy via Attenuating miR-29a-3p in Neonatal Rat Cardiomyocytes

BACKGROUND

Neuropeptide Y (NPY) has been well known to induce Cardiomyocyte Hypertrophy (CH), which is possibly caused by disruption of cardiac cell energy balance. As mitochondria is losely related to energy metabolism, in this study, we investigated the changes in mitochondrial Dynamics-related protein (Drp1) expression under the action of NPY. miRNA-29a, a endogenous noncoding small molecule RNA which is involved in many cardiac diseases, by using a bioinformatics tool, we found a potential binding site of miRNA-29a on the Drp1 mRNA, and suggesting that miRNA-29a might play a regulatory role.

OBJECTIVE

To investigate the role of miR-29a-3p in the process of NPY-induced CH, and further explore it's predicted relationship with Drp1.

METHODS

The expression levels of miR-29a-3p and Atrial Natriuretic Peptide (ANP) were performed by the method of fluorescence quantitative PCR, in addition, expression of Drp1 in treated and control groups were performed by western blot analysis.] Results: We found NPY leads to the CH and up-regulation of ANP expression levels. We also found significant up-regulation of Drp1 expression and down-regulation of miR-29a-3p expression in NPY-treated cells. The decrease in miR-29a-3p expression may lead the increase expression level of Drp1. We found that the expression of ANP increased after NPY treatment. When Drp1 protein was silenced, the high expression of ANP was inhibited.

CONCLUSION

In this study, we found up-regulation of Drp1 in cells treated with NPY. Drp1 mRNA is a predicted target for miR-29a-3p, and the expression of Drp1 was attenuated by miR-29a-3p. Therefore, NPY leads to down-regulation of miR-29a-3p expression, up-regulation of Drp1 expression, and NPY leads to CH. Correspondingly, miR-29a-3p can counteract the effects of NPY. This may be a new way, which could be used in diagnosis and treatment plan for CH.

The Effects of Neuropeptide Y Overexpression on the Mouse Model of Doxorubicin-Induced Cardiotoxicity

Doxorubicin is a potent anticancer drug with cardiotoxicity hampering its use. Neuropeptide Y (NPY) is the most abundant neuropeptide in the heart and a co-transmitter of the sympathetic nervous system that plays a role in cardiac diseases. The aim of this work was to study the impact of NPY on doxorubicin-induced cardiotoxicity. Transgenic mice overexpressing NPY in noradrenergic neurons (NPY-OE^DβH) and wild-type mice were treated with a single dose of doxorubicin. Doxorubicin caused cardiotoxicity in both genotypes as demonstrated by decreased weight gain, tendency to reduced ejection fraction, and changes in the expression of several genes relevant to cardiac pathology. Doxorubicin resulted in a tendency to lower ejection fraction in NPY-OE^DβH mice more than in wild-type mice. In addition, gain in the whole body lean mass gain was decreased only in NPY-OE^DβH mice, suggesting a more severe impact of doxorubicin in this genotype. The effects of doxorubicin on genes expressed in the heart were similar between NPY-OE^DβH and wild-type mice. The results demonstrate that doxorubicin at a relatively low dose caused significant cardiotoxicity. There were differences between NPY-OE^DβH and wild-type mice in their responses to doxorubicin that suggest NPY to increase susceptibility to cardiotoxicity. This may point to the therapeutic implications as suggested for NPY system in other cardiovascular diseases.

Effects of epidermal growth factor on transforming growth factor-beta1-induced epithelial-mesenchymal transition and potential mechanism in human corneal epithelial cells

AIM

To evaluate the effects of epidermal growth factor (EGF) on transforming growth factor-beta1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) in human corneal epithelial cells (HCECs).

METHODS

HCECs were cultured and treated with TGF-β1 for establishing the model of EMT in vitro. Biological effect of EGF on TGF-β1-induced EMT was evaluated. Proteins and mRNAs expression changes of E-cadherin, N-cadherin and Fibronectin (EMT-relative markers) after TGF-β1 or TGF-β1 combined EGF treatment were detected by Western blot and RT-PCR, respectively. Viability and migration of HCECs were measured by CCK-8, transwell cell migration assay and cell scratch wound healing assay. Activation of Smad2, ERK, p38, JNK and Akt signaling pathways were evaluated by Western blot. Inhibitors of relevant signaling pathways were added to the HCECs to explore the key signal mechanism.

RESULTS

With treatment of TGF-β1 only, three EMT-relative proteins and mRNA expression showed that EMT up-regulated in a concentration-dependent and time-dependent manner, with significantly decreasing cell viability (TGF-β1≥5 ng/mL, P<0.05) and increasing cell migration (TGF-β1≥5 ng/mL, P<0.01). The phosphorylation of Smad2 and p38 was a key process of TGF-β1-induced EMT. Meanwhile, EMT-relative proteins and mRNA expression showed that EGF inhibited TGF-β1-indued EMT, with significantly increasing cell viability (EGF≥10 ng/mL, P<0.01). It was noteworthy that EGF significantly enhanced cell migration although EMT was inhibited (EGF≥10 ng/mL, P<0.01), and the blockage of p38 (by SB202190, a p38 inhibitor) was a potential mechanism of this phenomenon.

CONCLUSION

EGF inhibits TGF-β1-induced EMT via suppressive p38, and promotes cells proliferation and migration in a non-EMT process by inhibiting p38 pathway.

Deletion of Neuropeptide Y Attenuates Cardiac Dysfunction and Apoptosis During Acute Myocardial Infarction

Increasing neuropeptide Y (NPY) has been shown to be a risk factor for cardiovascular diseases. However, its role and mechanism in myocardial infarction (MI) have not yet been fully understood. H9c2 cells and neonatal rat ventricular myocytes with loss of function of NPY and rats with global knockout were used in this study. MI model of rats was induced by the ligation of left coronary artery, and the extent of MI was analyzed through echocardiographic, pathological, and molecular analyses. Our data demonstrated that NPY expression was significantly increased in MI rats and hypoxia/hydrogen peroxide (H₂O₂)-treated cardiomyocytes. At the same time, NPY-knockout rats exhibited a remarkable decrease in infarct size, serum lactate dehydrogenase activity, cardiomyocyte apoptosis, and caspase-3 expression and activity and a strong improvement in heart contractile function compared with MI rats. Meanwhile, NPY small interfering RNA (siRNA) inhibited the cell apoptosis in H₂O₂-treated H9c2 cells and hypoxia-treated neonatal rat ventricular myocytes. NPY deletion increased miR-499 expression and decreased FoxO4 expression in MI in vivo and in vitro. Moreover, NPY type 1 receptor antagonist BIBO3304 can reverse miR-499 decrease and FoxO4 increase in H₂O₂-induced cardiomyocytes. NPY siRNA inhibited cell apoptosis in H₂O₂-treated H9c2 cells that were reversed by miR-499 inhibitor. Additionally, FoxO4 was validated as the direct target of miR-499. Moreover, BIBO3304 and FoxO4 siRNA significantly increased the cell activity, inhibited the cell apoptosis, and decreased caspase-3 expression and activity in H₂O₂-treated cardiomyocytes that NPY presented the opposite effect. Collectively, deletion of NPY reduced myocardial ischemia, improved cardiac function, and inhibited cardiomyocyte apoptosis by NPY type 1 receptor–miR-499–FoxO4 axis, which provides a new treatment for MI.

The Role of Neuropeptide Y in Cardiovascular Health and Disease

Neuropeptide Y (NPY) is an abundant sympathetic co-transmitter, widely found in the central and peripheral nervous systems and with diverse roles in multiple physiological processes. In the cardiovascular system it is found in neurons supplying the vasculature, cardiomyocytes and endocardium, and is involved in physiological processes including vasoconstriction, cardiac remodeling, and angiogenesis. It is increasingly also implicated in cardiovascular disease pathogenesis, including hypertension, atherosclerosis, ischemia/infarction, arrhythmia, and heart failure. This review will focus on the physiological and pathogenic role of NPY in the cardiovascular system. After summarizing the NPY receptors which predominantly mediate cardiovascular actions, along with their signaling pathways, individual disease processes will be considered. A thorough understanding of these roles may allow therapeutic targeting of NPY and its receptors.