Calcineurin/NFAT Activation-Dependence of Leptin Synthesis and Vascular Growth in Response to Mechanical Stretch

RyR2 Stabilizer Attenuates Cardiac Hypertrophy by Downregulating TNF-α/NF-κB/NLRP3 Signaling Pathway through Inhibiting Calcineurin

The effect of Ryanodine receptor2 (RyR2) and its stabilizer on cardiac hypertrophy is not well known. C57/BL6 mice underwent transverse aortic contraction (TAC) or sham surgery were administered dantrolene, the RyR2 stabilizer, or control drug. Dantrolene significantly alleviated TAC-induced cardiac hypertrophy in mice, and RNA sequencing was performed implying calcineurin/NFAT3 and TNF-α/NF-κB/NLRP3 as critical signaling pathways. Further expression analysis and Western blot with heart tissue as well as neonatal rat cardiomyocyte (NRCM) model confirmed dantrolene decreases the activation of calcineurin/NFAT3 signaling pathway and TNF-α/NF-κB/NLRP3 signaling pathway, which was similar to FK506 and might be attenuated by calcineurin overexpression. The present study shows for the first time that RyR2 stabilizer dantrolene attenuates cardiac hypertrophy by inhibiting the calcineurin, therefore downregulating the TNF-α/NF-κB/NLRP3 pathway.

Loss of IP3R-BKCa Coupling Is Involved in Vascular Remodeling in Spontaneously Hypertensive Rats

Mechanisms by which BK_Ca (large-conductance calcium-sensitive potassium) channels are involved in vascular remodeling in hypertension are not fully understood. Vascular smooth muscle cell (VSMC) proliferation and vascular morphology were compared between hypertensive and normotensive rats. BK_Ca channel activity, protein expression, and interaction with IP3R (inositol 1,4,5-trisphosphate receptor) were examined using patch clamp, Western blot analysis, and coimmunoprecipitation. On inside-out patches of VSMCs, the Ca²⁺-sensitivity and voltage-dependence of BK_Ca channels were similar between hypertensive and normotensive rats. In whole-cell patch clamp configuration, treatment of cells with the IP3R agonist, Adenophostin A (AdA), significantly increased BK_Ca channel currents in VSMCs of both strains of rats, suggesting IP3R-BK_Ca coupling; however, the AdA-induced increases in BK_Ca currents were attenuated in VSMCs of hypertensive rats, indicating possible IP3R-BK_Ca decoupling, causing BK_Ca dysfunction. Co-immunoprecipitation and Western blot analysis demonstrated that BK_Ca and IP3R proteins were associated together in VSMCs; however, the association of BK_Ca and IP3R proteins was dramatically reduced in VSMCs of hypertensive rats. Genetic disruption of IP3R-BK_Ca coupling using junctophilin-2 shRNA dramatically augmented Ang II-induced proliferation in VSMCs of normotensive rats. Subcutaneous infusion of NS1619, a BK_Ca opener, to reverse BK_Ca dysfunction caused by IP3R-BK_Ca decoupling significantly attenuated vascular hypertrophy in hypertensive rats. In summary, the data from this study demonstrate that loss of IP3R-BK_Ca coupling in VSMCs induces BK_Ca channel dysfunction, enhances VSMC proliferation, and thus, may contribute to vascular hypertrophy in hypertension.

Interruption of TRPC6-NFATC1 signaling inhibits NADPH oxidase 4 and VSMCs phenotypic switch in intracranial aneurysm

Intracranial aneurysm (IA) is a frequent cerebrovascular disorder with unclear pathogenesis. The vascular smooth muscle cells (VSMCs) phenotypic switch is essential for IA formation. It has been reported that Ca2+ overload and excessive reactive oxygen species (ROS) are involved in VSMCs phenotypic switch. The transient receptor potential canonical 6 (TRPC6) and NADPH oxidase 4 (NOX4) are the main pathway to participate in Ca2+ overload and ROS production in VSMCs. Ca2+ overload can activate calcineurin (CN), leading to nuclear factor of activated T cell (NFAT) dephosphorylation to regulate the target gene's transcription. We hypothesized that activation of TRPC6-NFATC1 signaling may upregulate NOX4 and involve in VSMCs phenotypic switch contributing to the progression of IA. Our results showed that the expressions of NOX4, p22phox, p47phox, TRPC6, CN and NFATC1 were significantly increased, and VSMCs underwent a significant phenotypic switch in IA tissue and cellular specimens. The VIVIT (NFATC1 inhibitor) and BI-749327 (TRPC6 inhibitor) treatment reduced the expressions of NOX4, p22phox and p47phox and the production of ROS, and significantly improved VSMCs phenotypic switch in IA rats and cells. Consistent results were obtained from IA Trpc6 knockout (Trpc6-/-) mice. Furthermore, the results also revealed that NFATC1 could regulate NOX4 transcription by binding to its promoter. Our findings reveal that interrupting the TRPC6-NFATC1 signaling inhibits NOX4 and improves VSMCs phenotypic switch in IA, and regulating Ca2+ homeostasis may be an important therapeutic strategy for IA.

RhoA Signaling in Neurodegenerative Diseases

Ras homolog gene family member A (RhoA) is a small GTPase of the Rho family involved in regulating multiple signal transduction pathways that influence a diverse range of cellular functions. RhoA and many of its downstream effector proteins are highly expressed in the nervous system, implying an important role for RhoA signaling in neurons and glial cells. Indeed, emerging evidence points toward a role of aberrant RhoA signaling in neurodegenerative diseases such as Parkinson’s disease, Alzheimer’s disease, Huntington’s disease, and amyotrophic lateral sclerosis. In this review, we summarize the current knowledge of RhoA regulation and downstream cellular functions with an emphasis on the role of RhoA signaling in neurodegenerative diseases and the therapeutic potential of RhoA inhibition in neurodegeneration.

Involvement of caveolae in hyperglycemia-induced changes in adiponectin and leptin expressions in vascular smooth muscle cells

Hyperglycemia exerts various harmful effects on the vasculature. Studies have shown an association between the levels of the adipokines leptin and adiponectin (APN) and vascular complications in diabetes mellitus. The aim of our study was to investigate the molecular mechanisms mediated by APN and leptin that are involved in hyperglycemia-induced vascular remodeling, especially at the level of oxidative stress and actin cytoskeleton dynamics. Rat aorta organ culture was used to investigate the effect of hyperglycemia on APN and leptin protein expression in vascular smooth muscle cells (VSMCs) using Western blot analysis and immunohistochemistry. Hyperglycemia lead to a significant increase in APN synthesis in VSMCs, mainly through caveolae, but this increase failed to provide vascular protection because of the decreased expression of APN receptors, especially AdipoR2, which was assessed by qPCR. In addition, hyperglycemia significantly upregulated leptin expression in VSMCs through caveolae and the RhoA/ROCK pathway. These variations lead to a marked increase in reactive oxygen species (ROS) production, detected by dihydroethidium (DHE) staining, and in NADPH oxidase type 4 (Nox4) expression. Moreover, Nox4 mediated the synthesis of APN in hyperglycemia in VSMCs. Finally, hyperglycemia activated the RhoA/ROCK pathway and subsequently induced the polymerization of globular actin (G-actin) into filamentous actin (F-actin), decreasing the G/F-actin ratio. Taken together, these data show that hyperglycemia increases oxidative stress and changes actin cytoskeleton dynamics in the aorta via caveolae, favoring vascular remodeling.

Vascular Health Triad in Humans With Hypertension-Not the Usual Suspects

Hypertension (HTN) affects more than one-third of the US population and remains the top risk factor for the development of cardiovascular disease (CVD). Identifying the underlying mechanisms for developing HTN are of critical importance because the risk of developing CVD doubles with ∼20 mmHg increase in systolic blood pressure (BP). Endothelial dysfunction, especially in the resistance arteries, is the primary site for initiation of sub-clinical HTN. Furthermore, inflammation and reactive oxygen and nitrogen species (ROS/RNS) not only influence the endothelium independently, but also have a synergistic influence on each other. Together, the interplay between inflammation, ROS and vascular dysfunction is referred to as the vascular health triad, and affects BP regulation in humans. While the interplay of the vascular health triad is well established, new underlying mechanistic targets are under investigation, including: Inducible nitric oxide synthase, hydrogen peroxide, hydrogen sulfide, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and nuclear factor activated T cells. This review outlines the role of these unusual suspects in vascular health and function in humans. This review connects the dots using these unusual suspects underlying inflammation, ROS and vascular dysfunction especially in individuals at risk of or with diagnosed HTN based on novel studies performed in humans.

Between Inflammation and Autophagy: The Role of Leptin-Adiponectin Axis in Cardiac Remodeling

Cardiac remodeling is the process by which the heart adapts to stressful stimuli, such as hypertension and ischemia/reperfusion; it ultimately leads to heart failure upon long-term exposure. Autophagy, a cellular catabolic process that was originally considered as a mechanism of cell death in response to detrimental stimuli, is thought to be one of the main mechanisms that controls cardiac remodeling and induces heart failure. Dysregulation of the adipokines leptin and adiponectin, which plays essential roles in lipid and glucose metabolism, and in the pathophysiology of the neuroendocrine and cardiovascular systems, has been shown to affect the autophagic response in the heart and to contribute to accelerate cardiac remodeling. The obesity-associated protein leptin is a pro-inflammatory, tumor-promoting adipocytokine whose elevated levels in obesity are associated with acute cardiovascular events, and obesity-related hypertension. Adiponectin exerts anti-inflammatory and anti-tumor effects, and its reduced levels in obesity correlate with the pathogenesis of obesity-associated cardiovascular diseases. Leptin- and adiponectin-induced changes in autophagic flux have been linked to cardiac remodeling and heart failure. In this review, we describe the different molecular mechanisms of hyperleptinemia- and hypoadiponectinemia-mediated pathogenesis of cardiac remodeling and the involvement of autophagy in this process. A better understanding of the roles of leptin, adiponectin, and autophagy in cardiac functions and remodeling, and the exact signal transduction pathways by which they contribute to cardiac diseases may well lead to discovery of new therapeutic agents for the treatment of cardiovascular remodeling.

Vascular Cells Proteome Associated with Bradykinin and Leptin Inflammation and Oxidative Stress Signals

Among the primary contributors to cardiovascular diseases are inflammation and oxidative imbalance within the vessel walls as well as the fibrosis of rat aortic smooth muscle cell (RASMC). Bradykinin (BK) and leptin are inflammatory modulators that are linked to vascular injury. In this study, we employed tandem LC-MS/MS to identify protein signatures that encompass protein abundance in RASMC treated with BK or leptin followed by systems biology analyses to gain insight into the biological pathways and processes linked to vascular remodeling. In the study, 1837 proteins were identified in control untreated RASMC. BK altered the expression of 72 (4%) and 120 (6.5%) proteins, whereas leptin altered the expression of 189 (10.2%) and 127 (6.5%) proteins after 24 and 48 h, respectively, compared to control RASMC. BK increased the protein abundance of leptin receptor, transforming growth factor-β. On the other hand, leptin increased the protein abundance of plasminogen activator inhibitor 1 but decreased the protein abundance of cofilin. BK and leptin induced the expression of inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β) and pathway analysis revealed the activation of mitogen-activated protein kinases (MAPKs) and AKT pathways. The proteome profile in response to BK and leptin revealed mechanistic interplay of multiple processes that modulate inflammation and oxidative stress signals in the vasculature.

Advances in Cardiovascular Biomarker Discovery

Cardiovascular diseases are the leading causes of mortality worldwide. Among them, hypertension and its pathological complications pose a major risk for the development of other cardiovascular diseases, including heart failure and stroke. Identifying novel and early stage biomarkers of hypertension and other cardiovascular diseases is of paramount importance in predicting and preventing the major morbidity and mortality associated with these diseases. Biomarkers of such diseases or predisposition to their development are identified by changes in a specific indicator’s expression between healthy individuals and patients. These include changes in protein and microRNA (miRNA) levels. Protein profiling using mass spectrometry and miRNA screening utilizing microarray and sequencing have facilitated the discovery of proteins and miRNA as biomarker candidates. In this review, we summarized some of the different, promising early stage protein and miRNA biomarker candidates as well as the currently used biomarkers for hypertension and other cardiovascular diseases. Although a number of promising markers have been identified, it is unlikely that a single biomarker will unambiguously aid in the classification of these diseases. A multi-marker panel-strategy appears useful and promising for classifying and refining risk stratification among patients with cardiovascular disease.

Stachydrine hydrochloride suppresses phenylephrine-induced pathological cardiac hypertrophy by inhibiting the calcineurin/nuclear factor of activated T-cell signalling pathway

The calcineurin (CaN)/nuclear factor of activated T-cell (NFAT) signalling pathway plays an important role in pathological cardiac hypertrophy. Here, we investigated the potential effects of stachydrine hydrochloride, a bioactive constituent extracted from the Chinese herb Leonurus japonicus Houtt. (Yimucao), on pathological cardiac hypertrophy during chronic α1-adrenergic receptor (α1-AR) activation and the underlying mechanisms. First, by transcriptome analysis, we determined that pathological hypertrophy models could be prepared after phenylephrine stimulation. In primary cultured neonatal rat ventricular myocytes, stachydrine hydrochloride reduced phenylephrine-induced cardiomyocyte surface area and the mRNA expression of cardiac hypertrophy biomarkers (atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), and β-myosin heavy chain/α-myosin heavy chain (β-MHC/α-MHC)). In addition, phenylephrine stimulation potently induced activation of the CaN/NFAT pathway. Interestingly, stachydrine hydrochloride inhibited CaN activation and reduced NFATc3 nuclear translocation in phenylephrine-stimulated neonatal rat ventricular myocytes. In mice treated with phenylephrine, stachydrine hydrochloride treatment decreased cardiac hypertrophy and regulated heart function. Collectively, our data show that stachydrine hydrochloride decreases cardiac hypertrophy in phenylephrine-stimulated hearts by inhibiting the CaN/NFAT pathway, which might contribute to alleviation of pathological cardiac hypertrophy and cardiac dysfunction by stachydrine hydrochloride after phenylephrine stimulation This also indicated that governing of CaN/NFAT pathway might serve as a preventive or therapeutic strategy for pathological cardiac hypertrophy.

Adults with Down syndrome challenge another paradigm: When aging no longer entails arterial hypertension

The paradigmatic relationship between aging and atherosclerotic cardiovascular events does not apply to all patient populations. Though trisomy 21 (T21) and its phenotypic expression, Down syndrome (DS), are conditions that involve premature aging, the cardiovascular system of adults with DS appears to be particularly spared from this early senescence. Despite a higher prevalence of some classic cardiovascular risk factors in adults with DS than in the general population, such as dyslipidemia, obesity, or sedentarism, these individuals do not develop hypertension or suffer major cardiovascular events as they age. The protective factors that prevent the development of hypertension in T21 are not well established. Genes like RCAN1 and DYRK1A, both on chromosome 21 and over-expressed in adults with DS, appear to play a major role in cardiovascular prevention. Their regulation of the renin-angiotensin-aldosterone system (RAAS) and neprilysin synthesis could underlie the constitutive protection against arterial hypertension in adults with DS and explain the absence of increased arterial stiffness in this population. A better understanding of these molecular pathways could have enormous implications for the clinical management of adults with DS and might foster the development of novel therapeutic targets in cardiovascular prevention for the general population.

Molecular Mechanisms of Adiponectin-Induced Attenuation of Mechanical Stretch-Mediated Vascular Remodeling

Hypertension induces vascular hypertrophy, which changes blood vessels structurally and functionally, leading to reduced tissue perfusion and further hypertension. It is also associated with dysregulated levels of the circulating adipokines leptin and adiponectin (APN). Leptin is an obesity-associated hormone that promotes vascular smooth muscle cell (VSMC) hypertrophy. APN is a cardioprotective hormone that has been shown to attenuate hypertrophic cardiomyopathy. In this study, we investigated the molecular mechanisms of hypertension-induced VSMC remodeling and the involvement of leptin and APN in this process. To mimic hypertension, the rat portal vein (RPV) was mechanically stretched, and the protective effects of APN on mechanical stretch-induced vascular remodeling and the molecular mechanisms involved were examined by using 10 μg/ml APN. Mechanically stretching the RPV significantly decreased APN protein expression after 24 hours and APN mRNA expression in a time-dependent manner in VSMCs. The mRNA expression of the APN receptors AdipoR1, AdipoR2, and T-cadherin significantly increased after 15 hours of stretch. The ratio of APN/leptin expression in VSMCs significantly decreased after 24 hours of mechanical stretch. Stretching the RPV for 3 days increased the weight and [³H]-leucine incorporation significantly, whereas APN significantly reduced hypertrophy in mechanically stretched vessels. Stretching the RPV for 10 minutes significantly decreased phosphorylation of LKB1, AMPK, and eNOS, while APN significantly increased p-LKB1, p-AMPK, and p-eNOS in stretched vessels. Mechanical stretch significantly increased p-ERK1/2 after 10 minutes, whereas APN significantly reduced stretch-induced ERK1/2 phosphorylation. Stretching the RPV also significantly increased ROS generation after 1 hour, whereas APN significantly decreased mechanical stretch-induced ROS production. Exogenous leptin (3.1 nM) markedly increased GATA-4 nuclear translocation in VSMCs, whereas APN significantly attenuated leptin-induced GATA-4 nuclear translocation. Our results decipher molecular mechanisms of APN-induced attenuation of mechanical stretch-mediated vascular hypertrophy, with the promising potential of ultimately translating this protective hormone into the clinic.

ROCK1 induces dopaminergic nerve cell apoptosis via the activation of Drp1-mediated aberrant mitochondrial fission in Parkinson's disease

Dopamine deficiency is mainly caused by apoptosis of dopaminergic nerve cells in the substantia nigra of the midbrain and the striatum and is an important pathologic basis of Parkinson’s disease (PD). Recent research has shown that dynamin-related protein 1 (Drp1)-mediated aberrant mitochondrial fission plays a crucial role in dopaminergic nerve cell apoptosis. However, the upstream regulatory mechanism remains unclear. Our study showed that Drp1 knockdown inhibited aberrant mitochondrial fission and apoptosis. Importantly, we found that ROCK1 was activated in an MPP⁺-induced PD cell model and that ROCK1 knockdown and the specific ROCK1 activation inhibitor Y-27632 blocked Drp1-mediated aberrant mitochondrial fission and apoptosis of dopaminergic nerve cells by suppressing Drp1 dephosphorylation/activation. Our in vivo study confirmed that Y-27632 significantly improved symptoms in a PD mouse model by inhibiting Drp1-mediated aberrant mitochondrial fission and apoptosis. Collectively, our findings suggest an important molecular mechanism of PD pathogenesis involving ROCK1-regulated dopaminergic nerve cell apoptosis via the activation of Drp1-induced aberrant mitochondrial fission.

Researchers in China have revealed how a protein molecule plays an early part in the molecular steps that can lead to Parkinson’s disease, which is caused by the death of nerve cells that make the neurotransmitter dopamine. Disruption of mitochondria, the energy-generating bodies inside cells, was already known to lead to the death of dopamine-producing cells. Rong Zhang, Guobing Li and colleagues at The Second Affiliated Hospital of Army Medical University in Chongqing, China traced the chain of cause and effect back to a protein called ROCK-1. Using a mouse model of Parkinson’s disease, they found that ROCK-1 activates another protein previously shown to trigger the disruption of mitochondria. ROCK-1’s early role in the sequence might make it a suitable target for treatment using drugs that inhibit its activity.

Leptin, An Adipokine With Central Importance in the Global Obesity Problem

Leptin has central importance in the global obesity and cardiovascular disease problem. Leptin is principally secreted by adipocytes and acts in the hypothalamus to suppress appetite and food intake, increase energy expenditure, and regulate body weight. Based on clinical translation of specific and networked actions, leptin affects the cardiovascular system and may be a marker and driver of cardiometabolic risk factors with interventions that are actionable by cardiologists. Leptin subnetwork analysis demonstrates a statistically significant role for ethnoculturally and socioeconomically appropriate lifestyle intervention in cardiovascular disease. Emergent mechanistic components and potential diagnostic or therapeutic targets include hexokinase 3, urocortins, clusterin, sialic acid-binding immunoglobulin-like lectin 6, C-reactive protein, platelet glycoprotein VI, albumin, pentraxin 3, ghrelin, obestatin prepropeptide, leptin receptor, neuropeptide Y, and corticotropin-releasing factor receptor 1. Emergent associated symptoms include weight change, eating disorders, vascular necrosis, chronic fatigue, and chest pain. Leptin-targeted therapies are reported for lipodystrophy and leptin deficiency, but they are investigational for leptin resistance, obesity, and other chronic diseases.

Effects of a traditional Chinese medicine formula and its extraction on muscle fiber characteristics in finishing pigs, porcine cell proliferation and isoforms of myosin heavy chain gene expression in myocytes

Objective

This study evaluated the effects of a traditional Chinese medicine formula (TCMF) on muscle fiber characteristics in finishing pigs and the effects of the formula’s extract (distilled water, ethyl acetate and petroleum ether extraction) on porcine cell proliferation and isoforms of myosin heavy chain (MyHC) gene expression in myocytes.

Methods

In a completely randomized design, ninety pigs were assigned to three diets with five replications per treatment and six pigs per pen. The diets included the basal diet (control group), TCMF1 (basal diet+2.5 g/kg TCMF) and TCMF2 (basal diet+5 g/kg TCMF). The psoas major muscle was obtained from pigs at the end of the experiment. Muscle fiber characteristics in the psoas major muscle were analyzed using myosin ATPase staining. Cell proliferation was measured using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) dye and cytometry. Isoforms of MyHC gene expression were detected by real-time quantitative polymerase chain reaction.

Results

The final body weight and carcass weight of finishing pigs were increased by TCMF1 (p<0.05), while the psoas major muscle cross-sectional area was increased by TCMF (p<0.05). The cross-sectional area and diameter of psoas major muscle fiber I, IIA, and IIB were increased by TCMF2 (p<0.05). The cross-sectional area and fiber diameter of psoas major muscle fiber IIA and IIB were increased by diet supplementation with TCMF1 (p<0.05). Psoas major muscle fiber IIA and IIB fiber density from the pigs fed the TCMF1 diet and the type IIB fiber density from the pigs fed the TCMF2 diet were lower compared to pigs fed the control diet (p<0.05). Pigs fed TCMF2 had a higher composition of type I fiber and a lower percentage of type IIB fiber in the psoas major muscle (p<0.05). The expression levels of MyHC I, MyHC IIa, and MyHC IIx mRNA increased and the amount of MyHC IIb mRNA decreased in the psoas major muscle from TCMF2, whereas MyHC I and MyHC IIx mRNA increased in the psoas major muscle from TCMF1 (p<0.05). Peroxisome proliferator-activated receptor γ coactivator-1α and CaN mRNA expression in the psoas major muscle were up-regulated by TCMF (p<0.05). Porcine skeletal muscle satellite cell proliferation was promoted by 4 μg/mL and 20 μg/mL TCMF water extraction (p<0.05). Both 1 μg/mL and 5 μg/mL of TCMF water extraction increased MyHC IIa, MyHC IIb, and MyHC IIx mRNA expression in porcine myocytes (p<0.05), while MyHC I mRNA expression in porcine myocytes was decreased by 5 μg/mL TCMF water extraction (p<0.05). Porcine myocyte MyHC I and MyHC IIx mRNA expression were increased, and MyHC IIa and MyHC IIb mRNA expression were down-regulated by 5 μg/mL TCMF ethyl acetate extraction (p<0.05). MyHC I and MyHC IIa mRNA expression in porcine myocytes were increased, and the MyHC IIb mRNA expression was decreased by 1 μg/mL TCMF ethyl acetate extraction (p<0.05). Four isoforms of MyHC mRNA expression in porcine myocytes were reduced by 5 μg/mL TCMF petroleum ether extraction (p<0.05). MyHC IIa mRNA expression in porcine myocytes increased and MyHC IIb mRNA expression decreased by 1 μg/mL in a TCMF petroleum ether extraction (p<0.05).

Conclusion

These results indicated that TCMF amplified the psoas major muscle cross-sectional area through changing muscle fiber characteristics in finishing pigs. This effect was confirmed as TCMF extraction promoted porcine cell proliferation and affected isoforms of MyHC gene expression in myocytes.