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Essandoh K, Yang L, Wang X, Huang W, Qin D, Hao J, Wang Y, Zingarelli B, Peng T, Fan GC. Blockade of exosome generation with GW4869 dampens the sepsis-induced inflammation and cardiac dysfunction. Biochim Biophys Acta Mol Basis Dis 2015; 1852:2362-71. [PMID: 26300484 DOI: 10.1016/j.bbadis.2015.08.010] [Citation(s) in RCA: 296] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 08/11/2015] [Accepted: 08/12/2015] [Indexed: 01/20/2023]
Abstract
Sepsis is an infection-induced severe inflammatory disorder that leads to multiple organ failure. Amongst organs affected, myocardial depression is believed to be a major contributor to septic death. While it has been identified that large amounts of circulating pro-inflammatory cytokines are culprit for triggering cardiac dysfunction in sepsis, the underlying mechanisms remain obscure. Additionally, recent studies have shown that exosomes released from bacteria-infected macrophages are pro-inflammatory. Hence, we examined in this study whether blocking the generation of exosomes would be protective against sepsis-induced inflammatory response and cardiac dysfunction. To this end, we pre-treated RAW264.7 macrophages with GW4869, an inhibitor of exosome biogenesis/release, followed by endotoxin (LPS) challenge. In vivo, we injected wild-type (WT) mice with GW4869 for 1h prior to endotoxin treatment or cecal ligation/puncture (CLP) surgery. We observed that pre-treatment with GW4869 significantly impaired release of both exosomes and pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) in RAW264.7 macrophages. At 12h after LPS treatment or CLP surgery, WT mice pre-treated with GW4869 displayed lower amounts of exosomes and pro-inflammatory cytokines in the serum than control PBS-injected mice. Accordingly, GW4869 treatment diminished the sepsis-induced cardiac inflammation, attenuated myocardial depression and prolonged survival. Together, our findings indicate that blockade of exosome generation in sepsis dampens the sepsis-triggered inflammatory response and thereby, improves cardiac function and survival.
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Ni R, Zheng D, Wang Q, Yu Y, Chen R, Sun T, Wang W, Fan GC, Greer PA, Gardiner RB, Peng T. Deletion of capn4 Protects the Heart Against Endotoxemic Injury by Preventing ATP Synthase Disruption and Inhibiting Mitochondrial Superoxide Generation. Circ Heart Fail 2015; 8:988-96. [PMID: 26246018 DOI: 10.1161/circheartfailure.115.002383] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Accepted: 08/05/2015] [Indexed: 12/16/2022]
Abstract
BACKGROUND Our recent study has demonstrated that inhibition of calpain by transgenic overexpression of calpastatin reduces myocardial proinflammatory response and dysfunction in endotoxemia. However, the underlying mechanisms remain to be determined. In this study, we used cardiomyocyte-specific capn4 knockout mice to investigate whether and how calpain disrupts ATP synthase and induces mitochondrial superoxide generation during endotoxemia. METHODS AND RESULTS Cardiomyocyte-specific capn4 knockout mice and their wild-type littermates were injected with lipopolysaccharides. Four hours later, calpain-1 protein and activity were increased in mitochondria of endotoxemic mouse hearts. Mitochondrial calpain-1 colocalized with and cleaved ATP synthase-α (ATP5A1), leading to ATP synthase disruption and a concomitant increase in mitochondrial reactive oxygen species generation during lipopolysaccharide stimulation. Deletion of capn4 or upregulation of ATP5A1 increased ATP synthase activity, prevented mitochondrial reactive oxygen species generation, and reduced proinflammatory response and myocardial dysfunction in endotoxemic mice. In cultured cardiomyocytes, lipopolysaccharide induced mitochondrial superoxide generation that was prevented by overexpression of mitochondria-targeted calpastatin or ATP5A1. Upregulation of calpain-1 specifically in mitochondria sufficiently induced superoxide generation and proinflammatory response, both of which were attenuated by ATP5A1 overexpression or mitochondria-targeted superoxide dismutase mimetics. CONCLUSIONS Cardiomyocyte-specific capn4 knockout protects the heart against lipopolysaccharide-induced injury in endotoxemic mice. Lipopolysaccharides induce calpain-1 accumulation in mitochondria. Mitochondrial calpain-1 disrupts ATP synthase, leading to mitochondrial reactive oxygen species generation, which promotes proinflammatory response and myocardial dysfunction during endotoxemia. These findings uncover a novel mechanism by which calpain mediates myocardial dysfunction in sepsis.
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Zheng D, Ma J, Yu Y, Li M, Ni R, Wang G, Chen R, Li J, Fan GC, Lacefield JC, Peng T. Silencing of miR-195 reduces diabetic cardiomyopathy in C57BL/6 mice. Diabetologia 2015; 58:1949-58. [PMID: 25994075 PMCID: PMC4499474 DOI: 10.1007/s00125-015-3622-8] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 04/14/2015] [Indexed: 12/18/2022]
Abstract
AIMS/HYPOTHESIS MicroRNAs (miRs) have been suggested as potential therapeutic targets for heart diseases. Inhibition of miR-195 prevents apoptosis in cardiomyocytes stimulated with palmitate and transgenic overexpression of miR-195 induces cardiac hypertrophy and heart failure. We investigated whether silencing of miR-195 reduces diabetic cardiomyopathy in a mouse model of streptozotocin (STZ)-induced type 1 diabetes. METHODS Type 1 diabetes was induced in C57BL/6 mice (male, 2 months old) by injections of STZ. RESULTS MiR-195 expression was increased and levels of its target proteins (B cell leukaemia/lymphoma 2 and sirtuin 1) were decreased in STZ-induced type 1 and db/db type 2 diabetic mouse hearts. Systemically delivering an anti-miR-195 construct knocked down miR-195 expression in the heart, reduced caspase-3 activity, decreased oxidative stress, attenuated myocardial hypertrophy and improved myocardial function in STZ-induced mice with a concurrent upregulation of B cell leukaemia/lymphoma 2 and sirtuin 1. Diabetes reduced myocardial capillary density and decreased maximal coronary blood flow in mice. Knockdown of miR-195 increased myocardial capillary density and improved maximal coronary blood flow in diabetic mice. Upregulation of miR-195 sufficiently induced apoptosis in cardiomyocytes and attenuated the angiogenesis of cardiac endothelial cells in vitro. Furthermore, inhibition of miR-195 prevented apoptosis in cardiac endothelial cells in response to NEFA, an important feature of diabetes. CONCLUSIONS/INTERPRETATION Therapeutic silencing of miR-195 reduces myocardial hypertrophy and improves coronary blood flow and myocardial function in diabetes, at least in part by reducing oxidative damage, inhibiting apoptosis and promoting angiogenesis. Thus, miR-195 may represent an alternative therapeutic target for diabetic heart diseases.
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Fan GC, Qin D, Wang X, Yang L, Huang W, Wang Y. Abstract 325: miR-223 Negatively Regulate Ischemia/Reperfusion-induced Cardiac Necroptosis. Circ Res 2015. [DOI: 10.1161/res.117.suppl_1.325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
It is well known that myocardial ischemia/reperfusion (I/R) causes myocyte apoptosis and necrosis. For many years, apoptosis was considered to be the only form of gene-regulated cell death, whereas necrosis was thought as a passive accidental cell death. Recent studies, however, clearly indicate that necrosis can be controlled by multiple genes, and RIPK1/3-regulated necrosis, called necroptosis, has gained well attention. We and others previously showed that miR-223, an anti-inflammatory miRNA, was greatly up-regulated in the infarcted heart. To test whether miR-223 regulates I/R-induced cardiac necroptosis, transgenic (TG) mice with cardiac-specific overexpression of miR-223 and miR-223 knockout (KO) mice were used and underwent global no-flow I/R (30min/1h). We observed that TG hearts displayed the better recovery of contractile function (+dP/dt: 92±4%), compared with wild-type (WT) hearts (65±3%). This improvement was accompanied with a 2.4-fold decrease in lactate dehydrogenase (LDH), a marker of necrosis, released from TG hearts, comparable to WTs. By contrast, KO-hearts showed the worse recovery of contractile function (+dP/dt: 41± 3%) than WTs (+dP/dt: 70±4%), and increased LDH release (3-fold). Notably, both TUNEL-staining and DNA fragmentation analysis for cardiac apoptosis showed no difference between groups. Western-blotting assays showed that protein levels of RIPK1, RIPK3 and MLKL, three known mediators in the necroptotic pathway, were reduced in TG hearts, whereas they were increased in KOs, compared to respective WT controls upon I/R. Furthermore, pre-injection of NEC-1s (1.65mg/kg), a specific inhibitor of necroptosis, into miR-223-KO mice, significantly improved cardiac function recovery during I/R, compared to saline-injected KOs. To elucidate the mechanisms underlying the miR-223-mediated cardiac necroptosis, we performed a series of experiments (bioinformatics, luciferase report assay, and western-blotting). Our results showed that miR-223 negatively regulated the expression of TNFR1 and death receptor 6 (DR6), two activators of the necroptotic pathway. Put together, this study indicates that miR-223 could control I/R-induced cardiac necroptosis via targeting the DR6/TNFR1-RIP1/3-MLKL pathway.
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Cai WF, Liu GS, Lam CK, Florea S, Qian J, Zhao W, Pritchard T, Haghighi K, Lebeche D, Lu LJ, Deng J, Fan GC, Hajjar RJ, Kranias EG. Up-regulation of micro-RNA765 in human failing hearts is associated with post-transcriptional regulation of protein phosphatase inhibitor-1 and depressed contractility. Eur J Heart Fail 2015; 17:782-93. [PMID: 26177627 DOI: 10.1002/ejhf.323] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 03/18/2015] [Accepted: 04/17/2015] [Indexed: 11/09/2022] Open
Abstract
AIMS Impaired sarcoplasmic reticulum (SR) Ca(2+) cycling and depressed contractility, a hallmark of human and experimental heart failure, has been partially attributed to increased protein phosphatase 1 (PP-1) activity, associated with down-regulation of its endogenous inhibitor-1. The levels and activity of inhibitor-1 are reduced in failing hearts, contributing to dephosphorylation and inactivation of key calcium cycling proteins. Therefore, we investigated the mechanisms that mediate decreases in inhibitor-1 by post-transcriptional modification. METHODS AND RESULTS Bioinformatics revealed that 17 human microRNAs may serve as modulators of inhibitor-1. However, real-time PCR analysis identified only one of these microRNAs, miR-765, as being increased in human failing hearts concomitant with decreased inhibitor-1 levels. Expression of miR-765 in HEK293 cells or mouse ventricular myocytes confirmed suppression of inhibitor-1 levels through binding of this miR-765 to the 3'-untranslated region of inhibitor-1 mRNA. To determine the functional significance of miR-765 in Ca(2+) cycling, pri-miR-765 as well as a non-translated nucleotide sequence (miR-Ctrl) were expressed in adult mouse ventricular myocytes. The inhibitor-1 expression levels were decreased, accompanied by enhanced PP-1 activity in the miR-765 cardiomyocytes, and these reflected depressed contractile mechanics and Ca(2+) transients, compared with the miR-Ctrl group. The depressive effects were associated with decreases in the phosphorylation of phospholamban and SR Ca(2+) load. These miR-765 negative inotropic effects were abrogated in inhibitor-1-deficient cardiomyocytes, suggesting its apparent specificity for inhibitor-1. CONCLUSIONS miR-765 levels are increased in human failing hearts. Such increases may contribute to depressed cardiac function through reduced inhibitor-1 expression and enhanced PP-1 activity, associated with reduced SR Ca(2+) load.
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Zheng D, Wang G, Li S, Fan GC, Peng T. Calpain-1 induces endoplasmic reticulum stress in promoting cardiomyocyte apoptosis following hypoxia/reoxygenation. Biochim Biophys Acta Mol Basis Dis 2015; 1852:882-92. [PMID: 25660447 DOI: 10.1016/j.bbadis.2015.01.019] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 01/09/2015] [Accepted: 01/31/2015] [Indexed: 12/24/2022]
Abstract
Both calpain activation and endoplasmic reticulum (ER) stress are implicated in ischemic heart injury. However, the role of calpain in ER stress remains largely elusive. This study investigated whether calpain activation causes ER stress, thereby mediating cardiomyocyte apoptosis in an in vitro model of hypoxia/re-oxygenation (H/R). In neonatal mouse cardiomyocytes and rat cardiomyocyte-like H9c2 cells, up-regulation of calpain-1 sufficiently induced ER stress, c-Jun N-terminal protein kinase1/2 (JNK1/2) activation and apoptosis. Inhibition of ER stress or JNK1/2 prevented apoptosis induced by calpain-1. In an in vitro model of H/R-induced injury in cardiomyocytes, H/R was induced by a 24-hour hypoxia followed by a 24-hour re-oxygenation. H/R activated calpain-1, induced ER stress and JNK1/2 activation, and triggered apoptosis. Inhibition of calpain and ER stress blocked JNK1/2 activation and prevented H/R-induced apoptosis. Furthermore, blockade of JNK1/2 signaling inhibited apoptosis following H/R. The role of calpain in ER stress was also demonstrated in an in vivo model of ischemia/reperfusion using transgenic mice over-expressing calpastatin. In summary, calpain-1 induces ER stress and JNK1/2 activation, thereby mediating apoptosis in cardiomyocytes. Accordingly, inhibition of calpain prevents ER stress, JNK1/2 activation and apoptosis in H/R-induced cardiomyocytes. Thus, ER stress/JNK1/2 activation may represent an important mechanism linking calpain-1 to ischemic injury.
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Ailawadi S, Wang X, Gu H, Fan GC. Pathologic function and therapeutic potential of exosomes in cardiovascular disease. Biochim Biophys Acta Mol Basis Dis 2014; 1852:1-11. [PMID: 25463630 DOI: 10.1016/j.bbadis.2014.10.008] [Citation(s) in RCA: 187] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 10/06/2014] [Accepted: 10/09/2014] [Indexed: 02/06/2023]
Abstract
The heart is a very complex conglomeration of organized interactions between various different cell types that all aid in facilitating myocardial function through contractility, sufficient perfusion, and cell-to-cell reception. In order to make sure that all features of the heart work effectively, it is imperative to have a well-controlled communication system among the different types of cells. One of the most important ways that the heart regulates itself is by the use of extracellular vesicles, more specifically, exosomes. Exosomes are types of nano-vesicles, naturally released from living cells. They are believed to play a critical role in intercellular communication through the means of certain mechanisms including direct cell-to-cell contact, long-range signals as well as electrical and extracellular chemical molecules. Exosomes contain many unique features like surface proteins/receptors, lipids, mRNAs, microRNAs, transcription factors and other proteins. Recent studies indicate that the exosomal contents are highly regulated by various stress and disease conditions, in turn reflective of the parent cell status. At present, exosomes are well appreciated to be involved in the process of tumor and infection disease. However, the research on cardiac exosomes is just emerging. In this review, we summarize recent findings on the pathologic effects of exosomes on cardiac remodeling under stress and disease conditions, including cardiac hypertrophy, peripartum cardiomyopathy, diabetic cardiomyopathy and sepsis-induced cardiovascular dysfunction. In addition, the cardio-protective effects of stress-preconditioned exosomes and stem cell-derived exosomes are also summarized. Finally, we discuss how to epigenetically reprogram exosome contents in host cells which makes them beneficial for the heart.
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Wen Z, Huang W, Feng Y, Cai W, Wang Y, Wang X, Liang J, Wani M, Chen J, Zhu P, Chen JM, Millard RW, Fan GC, Wang Y. MicroRNA-377 regulates mesenchymal stem cell-induced angiogenesis in ischemic hearts by targeting VEGF. PLoS One 2014; 9:e104666. [PMID: 25251394 PMCID: PMC4174502 DOI: 10.1371/journal.pone.0104666] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 07/10/2014] [Indexed: 02/07/2023] Open
Abstract
MicroRNAs have been appreciated in various cellular functions, including the regulation of angiogenesis. Mesenchymal-stem-cells (MSCs) transplanted to the MI heart improve cardiac function through paracrine-mediated angiogenesis. However, whether microRNAs regulate MSC induced angiogenesis remains to be clarified. Using microRNA microarray analysis, we identified a microRNA expression profile in hypoxia-treated MSCs and observed that among all dysregulated microRNAs, microRNA-377 was decreased the most significantly. We also validated that vascular endothelial growth factor (VEGF) is a target of microRNA-377 using dual-luciferase reporter assay and Western-blotting. Knockdown of endogenous microRNA-377 promoted tube formation in human umbilical vein endothelial cells. We then engineered rat MSCs with lentiviral vectors to either overexpress microRNA-377 (MSC miR-377) or knockdown microRNA-377 (MSC Anti-377) to investigate whether microRNA-377 regulated MSC-induced myocardial angiogenesis, using MSCs infected with lentiviral empty vector to serve as controls (MSC Null). Four weeks after implantation of the microRNA-engineered MSCs into the infarcted rat hearts, the vessel density was significantly increased in MSC Anti-377-hearts, and this was accompanied by reduced fibrosis and improved myocardial function as compared to controls. Adverse effects were observed in MSC miR-377-treated hearts, including reduced vessel density, impaired myocardial function, and increased fibrosis in comparison with MSC Null-group. These findings indicate that hypoxia-responsive microRNA-377 directly targets VEGF in MSCs, and knockdown of endogenous microRNA-377 promotes MSC-induced angiogenesis in the infarcted myocardium. Thus, microRNA-377 may serve as a novel therapeutic target for stem cell-based treatment of ischemic heart disease.
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Essandoh K, Fan GC. Role of extracellular and intracellular microRNAs in sepsis. Biochim Biophys Acta Mol Basis Dis 2014; 1842:2155-2162. [PMID: 25086335 DOI: 10.1016/j.bbadis.2014.07.021] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2014] [Revised: 07/22/2014] [Accepted: 07/23/2014] [Indexed: 01/09/2023]
Abstract
Sepsis is the major cause of death in the intensive care unit (ICU). Numerous biomarkers have been studied to identify the cause and severity of sepsis but these factors cannot differentiate between infectious and non-infectious inflammatory response. MicroRNAs (miRNAs) are non-coding RNA transcripts that regulate the expression of genes by repressing translation or degrading mRNA. Importantly, miRNAs can be released outside cells and easily detectable in bodily fluids such as blood, sweat, urine and breast milk. Numerous studies have explored the idea of utilizing extracellular miRNAs as biomarkers for sepsis by profiling the dysregulation of miRNAs in blood samples of sepsis patients. So far, miR-223, miR-146a and miR-150 have been identified to have promising prognostic and diagnostic value to sepsis. In addition, various intracellular miRNAs have been implicated to play critical roles in regulating the TLR-NF-κB pathway, which is a well-known inflammatory signaling pathway involved in the process of sepsis. Here, we summarize the recent progress on the role of extracellular and intracellular miRNAs in sepsis. Specifically, we discuss the possible role of circulating miRNA biomarkers for the diagnosis of sepsis and how intracellular miRNAs regulate the inflammatory responses in sepsis.
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Wang X, Huang W, Liu G, Cai W, Millard RW, Wang Y, Chang J, Peng T, Fan GC. Cardiomyocytes mediate anti-angiogenesis in type 2 diabetic rats through the exosomal transfer of miR-320 into endothelial cells. J Mol Cell Cardiol 2014; 74:139-50. [PMID: 24825548 DOI: 10.1016/j.yjmcc.2014.05.001] [Citation(s) in RCA: 312] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 04/14/2014] [Accepted: 05/02/2014] [Indexed: 12/14/2022]
Abstract
Exosomes, nano-vesicles naturally released from living cells, have been well recognized to play critical roles in mediating cell-to-cell communication. Given that diabetic hearts exhibit insufficient angiogenesis, it is significant to test whether diabetic cardiomyocyte-derived exosomes possess any capacity in regulating angiogenesis. In this study, we first observed that both proliferation and migration of mouse cardiac endothelial cells (MCECs) were inhibited when co-cultured with cardiomyocytes isolated from adult Goto-Kakizaki (GK) rats, a commonly used animal model of type 2 diabetes. However, GK-myocyte-mediated anti-angiogenic effects were negated upon addition of GW4869, an inhibitor of exosome formation/release, into the co-cultures. Next, exosomes were purified from the myocyte culture supernatants by differential centrifugation. While exosomes derived from GK myocytes (GK-exosomes) displayed similar size and molecular markers (CD63 and CD81) to those originated from the control Wistar rat myocytes (WT-exosomes), their regulatory role in angiogenesis is opposite. We observed that the MCEC proliferation, migration and tube-like formation were inhibited by GK-exosomes, but were promoted by WT-exosomes. Mechanistically, we found that GK-exosomes encapsulated higher levels of miR-320 and lower levels of miR-126 compared to WT-exosomes. Furthermore, GK-exosomes were effectively taken up by MCECs and delivered miR-320. In addition, transportation of miR-320 from myocytes to MCECs could be blocked by GW4869. Importantly, the exosomal miR-320 functionally down-regulated its target genes (IGF-1, Hsp20 and Ets2) in recipient MCECs, and overexpression of miR-320 inhibited MCEC migration and tube formation. GK exosome-mediated inhibitory effects on angiogenesis were removed by knockdown of miR-320. Together, these data indicate that cardiomyocytes exert an anti-angiogenic function in type 2 diabetic rats through exosomal transfer of miR-320 into endothelial cells. Thus, our study provides a novel mechanism underlying diabetes mellitus-induced myocardial vascular deficiency which may be caused by secretion of anti-angiogenic exosomes from cardiomyocyes.
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Zhang Y, Liu Y, Zhu XH, Zhang XD, Jiang DS, Bian ZY, Zhang XF, Chen K, Wei X, Gao L, Zhu LH, Yang Q, Fan GC, Lau WB, Ma X, Li H. Dickkopf-3 attenuates pressure overload-induced cardiac remodelling. Cardiovasc Res 2014; 102:35-45. [PMID: 24413772 DOI: 10.1093/cvr/cvu004] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
AIMS Dickkopf-3 (DKK3), a secreted protein in the Dickkopf family, is expressed in various tissues, including the heart, and has been shown to play an important role in tissue development. However, the biological function of DKK3 in the heart remains largely unexplored. This study aimed to examine the role of DKK3 in pathological cardiac hypertrophy. METHODS AND RESULTS We performed gain-of-function and loss-of-function studies using DKK3 cardiac-specific transgenic (TG) mice and DKK3 knockout (KO) mice (C57BL/6J background). Cardiac hypertrophy was induced by aortic banding. Cardiac hypertrophy was evaluated by echocardiographic, haemodynamic, pathological, and molecular analyses. Our results demonstrated that the loss of DKK3 exaggerated pressure overload-induced cardiac hypertrophy, fibrosis, and dysfunction, whereas the overexpression of DKK3 protected the heart against pressure overload-induced cardiac remodelling. These beneficial effects were associated with the inhibition of the ASK1-JNK/p38 (apoptosis signal-regulating kinase 1-c-Jun N-terminal kinase/p38) signalling cascade. Parallel in vitro experiments confirmed these in vivo observations. Co-immunoprecipitation experiments suggested that physical interactions occurred between DKK3 and ASK1. Moreover, rescue experiments indicated that, in DKK3 TG mice, the activation of ASK1 using a cardiac-specific conditional ASK1 transgene reduced the functionality of DKK3 in response to pressure overload; furthermore, the inactivation of ASK1 by dominant-negative ASK1 rescued pressure overload-induced cardiac abnormalities in DKK3 KO mice. CONCLUSION Taken together, our findings indicate that DKK3 acts as a cardioprotective regulator of pathological cardiac hypertrophy and that this function largely occurs via the regulation of ASK1-JNK/p38 signalling.
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Jiang DS, Liu Y, Zhou H, Zhang Y, Zhang XD, Zhang XF, Chen K, Gao L, Peng J, Gong H, Chen Y, Yang Q, Liu PP, Fan GC, Zou Y, Li H. Interferon regulatory factor 7 functions as a novel negative regulator of pathological cardiac hypertrophy. Hypertension 2014; 63:713-22. [PMID: 24396025 DOI: 10.1161/hypertensionaha.113.02653] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Cardiac hypertrophy is a complex pathological process that involves multiple factors including inflammation and apoptosis. Interferon regulatory factor 7 (IRF7) is a multifunctional regulator that participates in immune regulation, cell differentiation, apoptosis, and oncogenesis. However, the role of IRF7 in cardiac hypertrophy remains unclear. We performed aortic banding in cardiac-specific IRF7 transgenic mice, IRF7 knockout mice, and the wild-type littermates of these mice. Our results demonstrated that IRF7 was downregulated in aortic banding-induced animal hearts and cardiomyocytes that had been treated with angiotensin II or phenylephrine for 48 hours. Accordingly, heart-specific overexpression of IRF7 significantly attenuated pressure overload-induced cardiac hypertrophy, fibrosis, and dysfunction, whereas loss of IRF7 led to opposite effects. Moreover, IRF7 protected against angiotensin II-induced cardiomyocyte hypertrophy in vitro. Mechanistically, we identified that IRF7-dependent cardioprotection was mediated through IRF7 binding to inhibitor of κB kinase-β, and subsequent nuclear factor-κB inactivation. In fact, blocking nuclear factor-κB signaling with cardiac-specific inhibitors of κBα(S32A/S36A) super-repressor transgene counteracted the adverse effect of IRF7 deficiency. Conversely, activation of nuclear factor-κB signaling via a cardiac-specific conditional inhibitor of κB kinase-β(S177E/S181E) (constitutively active) transgene negated the antihypertrophic effect of IRF7 overexpression. Our data demonstrate that IRF7 acts as a novel negative regulator of pathological cardiac hypertrophy by inhibiting nuclear factor-κB signaling and may constitute a potential therapeutic target for pathological cardiac hypertrophy.
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Liu Y, Jiang XL, Liu Y, Jiang DS, Zhang Y, Zhang R, Chen Y, Yang Q, Zhang XD, Fan GC, Li H. Toll-interacting protein (Tollip) negatively regulates pressure overload-induced ventricular hypertrophy in mice. Cardiovasc Res 2013; 101:87-96. [PMID: 24285748 DOI: 10.1093/cvr/cvt232] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
AIMS Toll-interacting protein (Tollip) is a critical regulator of the Toll-like receptor-mediated signalling pathway. However, the role of Tollip in chronic pressure overload-induced cardiac hypertrophy remains unclear. This study aimed to determine the functional significance of Tollip in the regulation of aortic banding-induced cardiac remodelling and its underlying mechanisms. METHODS AND RESULTS First, we observed that Tollip was down-regulated in human failing hearts and murine hypertrophic hearts, as determined by western blotting and RT-PCR. Using cultured neonatal rat cardiomyocytes, we found that adenovirus vector-mediated overexpression of Tollip limited angiotensin II-induced cell hypertrophy; whereas knockdown of Tollip by shRNA exhibited the opposite effects. We then generated a transgenic (TG) mouse model with cardiac specific-overexpression of Tollip and subjected them to aortic banding (AB) for 8 weeks. When compared with AB-treated wild-type mouse hearts, Tollip-TGs showed a significant attenuation of cardiac hypertrophy, fibrosis, and dysfunction, as measured by echocardiography, immune-staining, and molecular/biochemical analysis. Conversely, a global Tollip-knockout mouse model revealed an aggravated cardiac hypertrophy and accelerated maladaptation to chronic pressure overloading. Mechanistically, we discovered that Tollip interacted with AKT and suppressed its downstream signalling pathway. Pre-activation of AKT in cardiomyocytes largely offset the Tollip-elicited anti-hypertrophic effects. CONCLUSION Our results provide the first evidence that Tollip serves as a negative regulator of pathological cardiac hypertrophy by blocking the AKT signalling pathway.
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Zhang Y, Zhang XF, Gao L, Liu Y, Jiang DS, Chen K, Yang Q, Fan GC, Zhang XD, Huang C. Growth/differentiation factor 1 alleviates pressure overload-induced cardiac hypertrophy and dysfunction. Biochim Biophys Acta Mol Basis Dis 2013; 1842:232-44. [PMID: 24275554 DOI: 10.1016/j.bbadis.2013.11.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 11/15/2013] [Accepted: 11/17/2013] [Indexed: 11/26/2022]
Abstract
Pathological cardiac hypertrophy is a major risk factor for developing heart failure, the leading cause of death in the world. Growth/differentiation factor 1 (GDF1), a transforming growth factor-β family member, is a regulator of cell growth and differentiation in both embryonic and adult tissues. Evidence from human and animal studies suggests that GDF1 may play an important role in cardiac physiology and pathology. However, a critical role for GDF1 in cardiac remodelling has not been investigated. Here, we performed gain-of-function and loss-of-function studies using cardiac-specific GDF1 knockout mice and transgenic mice to determine the role of GDF1 in pathological cardiac hypertrophy, which was induced by aortic banding (AB). The extent of cardiac hypertrophy was evaluated by echocardiographic, hemodynamic, pathological, and molecular analyses. Our results demonstrated that cardiac specific GDF1 overexpression in the heart markedly attenuated cardiac hypertrophy, fibrosis, and cardiac dysfunction, whereas loss of GDF1 in cardiomyocytes exaggerated the pathological cardiac hypertrophy and dysfunction in response to pressure overload. Mechanistically, we revealed that the cardioprotective effect of GDF1 on cardiac remodeling was associated with the inhibition of the MEK-ERK1/2 and Smad signaling cascades. Collectively, our data suggest that GDF1 plays a protective role in cardiac remodeling via the negative regulation of the MEK-ERK1/2 and Smad signaling pathways.
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Jiang DS, Luo YX, Zhang R, Zhang XD, Chen HZ, Zhang Y, Chen K, Zhang SM, Fan GC, Liu PP, Liu DP, Li H. Interferon regulatory factor 9 protects against cardiac hypertrophy by targeting myocardin. Hypertension 2013; 63:119-27. [PMID: 24144649 DOI: 10.1161/hypertensionaha.113.02083] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Pathological cardiac hypertrophy is a major risk factor for heart failure. In this study, we identified interferon regulatory factor 9 (IRF9), a member of the IRF family, as a previously unidentified negative regulator of cardiac hypertrophy. The level of IRF9 expression was remarkably elevated in the hearts from animals with aortic banding-induced cardiac hypertrophy. IRF9-deficient mice exhibited pronounced cardiac hypertrophy after pressure overload, as demonstrated by increased cardiomyocyte size, extensive fibrosis, reduced cardiac function, and enhanced expression of hypertrophy markers, whereas transgenic mice with cardiac-specific overexpression of murine IRF9 exhibited a significant reduction in the hypertrophic response. Mechanistically, IRF9 competes with p300 for binding to the transcription activation domain of myocardin, a coactivator of serum response factor (SRF). This interaction markedly suppresses the transcriptional activity of myocardin because IRF9 overexpression strongly inhibits the ability of myocardin to activate CArG box-dependent reporters. These results provide compelling evidence that IRF9 inhibits the development of cardiac hypertrophy by suppressing the transcriptional activity of myocardin in the heart.
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Jiang DS, Zhang XF, Gao L, Zong J, Zhou H, Liu Y, Zhang Y, Bian ZY, Zhu LH, Fan GC, Zhang XD, Li H. Signal regulatory protein-α protects against cardiac hypertrophy via the disruption of toll-like receptor 4 signaling. Hypertension 2013; 63:96-104. [PMID: 24101669 DOI: 10.1161/hypertensionaha.113.01506] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Signal regulatory protein-α (SIRPA/SIRPα) is a transmembrane protein that is expressed in various tissues, including the heart. Previous studies have demonstrated that SIRPA is involved in multiple biological processes, including macrophage multinucleation, skeletal muscle differentiation, neuronal survival, protection against diabetes mellitus, and negative regulation of immune cells. However, the role of SIRPA in cardiac hypertrophy remains unknown. To examine the role of SIRPA in pathological cardiac hypertrophy, we used SIRPA knockout mice and transgenic mice that overexpressed mouse SIRPA in the heart. Cardiac hypertrophy was evaluated by echocardiographic, hemodynamic, pathological, and molecular analyses. We observed downregulation of SIRPA expression in dilated cardiomyopathy human hearts and in animal hearts after aortic banding surgery. Accordingly, SIRPA(-/-) mice displayed augmented cardiac hypertrophy, which was accompanied by increased cardiac fibrosis and reduced contractile function, as compared with SIRPA(+/+) mice 4 weeks after aortic banding. In contrast, transgenic mice with the cardiac-specific SIRPA overexpression exhibited the opposite phenotype in response to pressure overload. Likewise, SIRPA protected against angiotensin II-induced cardiomyocyte hypertrophy in vitro. Mechanistically, we revealed that SIRPA-mediated protection during cardiac hypertrophy involved inhibition of the Toll-like receptor 4/nuclear factor-κB signaling axis. Furthermore, we demonstrated that the disruption of Toll-like receptor 4 rescued the adverse effects of SIRPA deficiency on pressure overload-triggered cardiac remodeling. Thus, our results identify that SIRPA plays a protective role in cardiac hypertrophy through negative regulation of the Toll-like receptor 4/nuclear factor-κB pathway.
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Li Q, Guo J, Lin X, Yang X, Ma Y, Fan GC, Chang J. An intragenic SRF-dependent regulatory motif directs cardiac-specific microRNA-1-1/133a-2 expression. PLoS One 2013; 8:e75470. [PMID: 24058688 PMCID: PMC3772891 DOI: 10.1371/journal.pone.0075470] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 08/14/2013] [Indexed: 01/18/2023] Open
Abstract
Transcriptional regulation is essential for any gene expression including microRNA expression. MiR-1-1 and miR-133a-2 are essential microRNAs (miRs) involved in cardiac and skeletal muscle development and diseases. Early studies reveal two regulatory enhancers, an upstream and an intragenic, that direct the miR-1-1 and miR-133a-2 transcripts. In this study, we identify a unique serum response factor (SRF) binding motif within the enhancer through bioinformatic approaches. This motif is evolutionarily conserved and is present in a range of organisms from yeast, flies, to humans. We provide evidence to demonstrate that this regulatory motif is SRF-dependent in vitro by electrophoretic mobility shift assay, luciferase activity assay, and endogenous chromatin immunoprecipitation assay followed by DNA sequence confirmation, and in vivo by transgenic lacZ reporter mouse studies. Importantly, our transgenic mice indicate that this motif is indispensable for the expression of miR1-1/133a-2 in the heart, but not necessary in skeletal muscle, while the enhancer is sufficient for miR1-1/133a-2 gene expression in both tissues. The mutation of the motif alone completely abolishes miR-1-1/133a-2 gene expression in the animal heart, but not in the skeletal muscle. Our findings reveal an additional architecture of regulatory complex directing miR-1-1/133a-1 gene expression, and demonstrate how this intragenic enhancer differentially manages the expression of the two miRs in the heart and skeletal muscle, respectively.
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Jiang DS, Bian ZY, Zhang Y, Zhang SM, Liu Y, Zhang R, Chen Y, Yang Q, Zhang XD, Fan GC, Li H. Role of interferon regulatory factor 4 in the regulation of pathological cardiac hypertrophy. Hypertension 2013; 61:1193-202. [PMID: 23589561 DOI: 10.1161/hypertensionaha.111.00614] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
IRF4, a member of the interferon regulatory factor (IRF) family, was previously shown to be restricted in the immune system and involved in the differentiation of immune cells. However, we interestingly observed that IRF4 was also highly expressed in both human and animal hearts. Given that several transcription factors have been shown to regulate the pathological cardiac hypertrophy, we then ask whether IRF4, as a new transcription factor, plays a critical role in pressure overload-elicited cardiac remodeling. A transgenic mouse model with cardiac-specific overexpression of IRF4 was generated and subjected to an aortic banding for 4 to 8 weeks. Our results demonstrated that overexpression of IRF4 aggravated pressure overload-triggered cardiac hypertrophy, fibrosis, and dysfunction. Conversely, IRF4 knockout mice showed an attenuated hypertrophic response to chronic pressure overload. Mechanistically, we discovered that the expression and activation of cAMP response element-binding protein (CREB) were significantly increased in IRF4-overexpressing hearts, while being greatly reduced in IRF4-KO hearts on aortic banding, compared with control hearts, respectively. Similar results were observed in ex vivo cultured neonatal rat cardiomyocytes on the treatment with angiotensin II. Inactivation of CREB by dominant-negative mutation (dnCREB) offset the IRF4-mediated hypertrophic response in angiotensin II-treated myocytes. Furthermore, we identified that the promoter region of CREB contains 3 IRF4 binding sites. Altogether, these data indicate that IRF4 functions as a necessary modulator of hypertrophic response by activating the transcription of CREB in hearts. Thus, our study suggests that IRF4 might be a novel target for the treatment of pathological cardiac hypertrophy and failure.
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69
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Zhu H, Fan GC. Whether Circulating miRNAs or miRNA-Carriers Serve as Biomarkers for Acute Myocardial Infarction. JOURNAL OF BIOMARKERS IN DRUG DEVELOPMENT 2012; 1. [PMID: 25197685 DOI: 10.4172/jbdd.1000e103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Acute myocardial infarction (AMI) remains a major cause of death in the US. An early and reliable diagnosis may warrant immediate initiation of reperfusion therapy to potentially improve the survival rate among the AMI patients. Currently, cardiac troponins (i.e. cTnT and cTnI) and creatine kinase MB (CK-MB) are widely used for AMI diagnosis. However, elevation of these biomarkers is also observed in human patients with myocarditis, aortic dissection, pulmonary embolism, congestive heart failure and renal failure. Furthermore, measurable amounts of troponin proteins are usually not released from damaged myocardium before 4 to 8 h after onset of symptoms, making an early biomarker-based diagnosis of AMI rather difficult. Therefore, new biomarkers with high sensitivity and specificity in early diagnosis of AMI are greatly needed.
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Ma J, Wei M, Wang Q, Li J, Wang H, Liu W, Lacefield JC, Greer PA, Karmazyn M, Fan GC, Peng T. Deficiency of Capn4 gene inhibits nuclear factor-κB (NF-κB) protein signaling/inflammation and reduces remodeling after myocardial infarction. J Biol Chem 2012; 287:27480-9. [PMID: 22753411 DOI: 10.1074/jbc.m112.358929] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Calpain has been implicated in acute myocardial injury after myocardial infarction (MI). However, the causal relationship between calpain and post-MI myocardial remodeling has not been fully understood. This study examined whether deletion of Capn4, essential for calpain-1 and calpain-2 activities, reduces myocardial remodeling and dysfunction following MI, and if yes, whether these effects of Capn4 deletion are associated with NF-κB signaling and inflammatory responses in the MI heart. A novel mouse model with cardiomyocyte-specific deletion of Capn4 (Capn4-ko) was employed. MI was induced by left coronary artery ligation. Deficiency of Capn4 dramatically reduced the protein levels and activities of calpain-1 and calpain-2 in the Capn4-ko heart. In vivo cardiac function was relatively improved in Capn4-ko mice at 7 and 30 days after MI when compared with their wild-type littermates. Deletion of Capn4 reduced apoptosis, limited infarct expansion, prevented left ventricle dilation, and reduced mortality in Capn4-ko mice. Furthermore, cardiomyocyte cross-sectional areas and myocardial collagen deposition were significantly attenuated in Capn4-ko mice, which were accompanied by down-regulation of hypertrophic genes and profibrotic genes. These effects of Capn4 knock-out correlated with restoration of IκB protein and inhibition of NF-κB activation, leading to suppression of proinflammatory cytokine expression and inflammatory cell infiltration in the Capn4-ko heart after MI. In conclusion, deficiency of Capn4 reduces adverse myocardial remodeling and myocardial dysfunction after MI. These effects of Capn4 deletion may be mediated through prevention of IκB degradation and NF-κB activation, resulting in inhibition of inflammatory responses.
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Zhang X, Wang X, Zhu H, Kranias EG, Tang Y, Peng T, Chang J, Fan GC. Hsp20 functions as a novel cardiokine in promoting angiogenesis via activation of VEGFR2. PLoS One 2012; 7:e32765. [PMID: 22427880 PMCID: PMC3299679 DOI: 10.1371/journal.pone.0032765] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 01/30/2012] [Indexed: 01/21/2023] Open
Abstract
Heat shock proteins (Hsps) are well appreciated as intrinsic protectors of cardiomyocytes against numerous stresses. Recent studies have indicated that Hsp20 (HspB6), a small heat shock protein, was increased in blood from cardiomyopathic hamsters. However, the exact source of the increased circulating Hsp20 and its potential role remain obscure. In this study, we observed that the circulating Hsp20 was increased in a transgenic mouse model with cardiac-specific overexpression of Hsp20, compared with wild-type mice, suggesting its origin from cardiomyocytes. Consistently, culture media harvested from Hsp20-overexpressing cardiomyocytes by Ad.Hsp20 infection contained an increased amount of Hsp20, compared to control media. Furthermore, we identified that Hsp20 was secreted through exosomes, independent of the endoplasmic reticulum-Golgi pathway. To investigate whether extracellular Hsp20 promotes angiogenesis, we treated human umbilical vein endothelial cells (HUVECs) with recombinant human Hsp20 protein, and observed that Hsp20 dose-dependently promoted HUVEC proliferation, migration and tube formation. Moreover, a protein binding assay and immunostaining revealed an interaction between Hsp20 and VEGFR2. Accordingly, stimulatory effects of Hsp20 on HUVECs were blocked by a VEGFR2 neutralizing antibody and CBO-P11 (a VEGFR inhibitor). These in vitro data are consistent with the in vivo findings that capillary density was significantly enhanced in Hsp20-overexpressing hearts, compared to non-transgenic hearts. Collectively, our findings demonstrate that Hsp20 serves as a novel cardiokine in regulating myocardial angiogenesis through activation of the VEGFR signaling cascade.
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Wang X, Zhu H, Zhang X, Liu Y, Chen J, Medvedovic M, Li H, Weiss MJ, Ren X, Fan GC. Loss of the miR-144/451 cluster impairs ischaemic preconditioning-mediated cardioprotection by targeting Rac-1. Cardiovasc Res 2012; 94:379-90. [PMID: 22354898 DOI: 10.1093/cvr/cvs096] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
AIMS While a wealth of data has uncovered distinct microRNA (miR) expression alterations in hypertrophic and ischaemic/reperfused (I/R) hearts, little is known about miR regulation and response to ischaemic preconditioning (IPC). METHODS AND RESULTS We analysed miRs in murine hearts preconditioned with six cycles of 4 min ischaemia via coronary artery occlusion, followed by 4 min reperfusion in vivo. Both miRs within the miR-144/451 cluster were the most elevated among a cohort of 21 dysregulated miRs in preconditioned hearts, compared with shams. To investigate the significance of this finding, we examined IPC-mediated cardioprotection within a miR-144/451-knockout (KO) mouse model. Wild-type (WT) hearts exposed to IPC followed by I/R (30 min/24 h) showed a smaller infarction size compared with mice treated with I/R alone. In contrast, IPC failed to protect miR-144/451-KO hearts against infarct caused by I/R treatment. Thus, the miR-144/451 cluster is required for IPC-elicited cardioprotection. Rac-1, a key component of NADPH oxidase, was mostly up-regulated in KO hearts among three bona fide targets (Rac-1, 14-3-3ζ, and CUGBP2) for both miR-144 and miR-451. Accordingly, reactive oxygen species (ROS) levels were markedly increased in KO hearts upon IPC, compared with IPC-WT hearts. Pre-treatment of KO hearts with a Rac-1 inhibitor NSC23766 (20 mg/kg, ip) reduced IPC-triggered ROS levels and restored IPC-elicited cardioprotection. Using antagomiRs, we showed that miR-451 was largely responsible for IPC-mediated cardioprotection. CONCLUSION Loss of the miR-144/451 cluster limits IPC cardioprotection by up-regulating Rac-1-mediated oxidative stress signalling.
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Fan GC. Role of heat shock proteins in stem cell behavior. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 111:305-22. [PMID: 22917237 DOI: 10.1016/b978-0-12-398459-3.00014-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Stress response is well appreciated to induce the expression of heat shock proteins (Hsps) in the cell. Numerous studies have demonstrated that Hsps function as molecular chaperones in the stabilization of intracellular proteins, repairing damaged proteins, and assisting in protein translocation. Various kinds of stem cells (embryonic stem cells, adult stem cells, or induced pluripotent stem cells) have to maintain their stemness and, under certain circumstances, undergo stress. Therefore, Hsps should have an important influence on stem cells. Actually, numerous studies have indicated that some Hsps physically interact with a number of transcription factors as well as intrinsic and extrinsic signaling pathways. Importantly, alterations in Hsp expression have been demonstrated to affect stem cell behavior including self-renewal, differentiation, sensitivity to environmental stress, and aging. This chapter summarizes recent findings related to (1) the roles of Hsps in maintenance of stem cell dormancy, proliferation, and differentiation; (2) the expression signature of Hsps in embryonic/adult stem cells and differentiated stem cells; (3) the protective roles of Hsps in transplanted stem cells; and (4) the possible roles of Hsps in stem cell aging.
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Zhu H, Wang X, Zhang X, Kranias EG, Liang Q, Fan GC. Abstract P046: Hsp20 Promotes Cardiac Autophagy via Interaction with Beclin-1. Circ Res 2011. [DOI: 10.1161/res.109.suppl_1.ap046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hsp20 has been shown to prevent stress-triggered cardiac injury. However, it remains obscure whether Hsp20-elicited cardioprotection is associated with the activation of autophagy. We first assessed cardiac autophagy in a transgenic (TG) mouse model with 10-fold overexpression of Hsp20 by immunoblotting. Levels of two autophagy markers (LC3II and Beclin1) were increased by 1.6- and 2.2-fold, respectively, in Hsp20-hearts, compared to WTs. To examine whether Hsp20 activates autophagic flux in the heart, mice were
i.p.
injected with chloroquine (CQ, 50mg/kg), an inhibitor for autophagosome-lysosome fusion, for 4h. Cadaverine dye-binding analysis showed that autophagy levels were increased by 1.5-fold in CQ-treated Hsp20-hearts compared to saline controls. To examine whether increased autophagy levels contribute to Hsp20-induced cardioprotection, 3-methyladenine (3-MA, an inhibitor for autophgy) was
i.p
. injected into TG mice (30mg/kg). One hour later, hearts were subjected to global no-flow ischemia/reperfusion (I/R: 45min/1h), and showed that contractile function (+dP/dt) was recovered by 93α 5 % in saline-treated Hsp20-hearts, comparable to 74 α 6 % recovery in 3-MA-treated TGs (n=6, p<0.05), indicating that the activation of autophagy by Hsp20 is beneficial for hearts upon I/R. To exclude
in vivo
compensatory effects, Hsp20 was delivered into isolated adult cardiomyocytes by adenoviral vector. Western-blotting analysis indicated that acute expression of Hsp20 increased the levels of LC3II and Beclin1 by ∼2-fold, compared to GFP control. Accordingly, overexpression of Hsp20 augmented myocyte survival upon addition of H
2
O
2
, as related to GFP-control. Furthermore, co-infection with AdBeclin1-siRNA attenuated the protective effects of Hsp20 in myocytes upon H
2
O
2
stress. Excitingly, Hsp20 was found to localize at the LC3-labeled autophagosome. Indeed, co-immunoprecipitation results showed an interaction of Hsp20 with Beclin-1 in the heart. Moreover, a competitive ELISA assay revealed that Hsp20 dose-dependently suppressed the interaction of Beclin1/Bcl-2, a known complex negatively regulating autophagy. In summary, Hsp20 activates cardiac autophagic flux via interaction with Beclin1, thereby confering cadioprotection.
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Haghighi K, Pritchard T, Bossuyt J, Waggoner JR, Yuan Q, Fan GC, Osinska H, Anjak A, Rubinstein J, Robbins J, Bers DM, Kranias EG. The human phospholamban Arg14-deletion mutant localizes to plasma membrane and interacts with the Na/K-ATPase. J Mol Cell Cardiol 2011; 52:773-82. [PMID: 22155237 DOI: 10.1016/j.yjmcc.2011.11.012] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 11/20/2011] [Indexed: 12/18/2022]
Abstract
Depressed Ca-handling in cardiomyocytes is frequently attributed to impaired sarcoplasmic reticulum (SR) function in human and experimental heart failure. Phospholamban (PLN) is a key regulator of SR and cardiac function, and PLN mutations in humans have been associated with dilated cardiomyopathy (DCM). We previously reported the deletion of the highly conserved amino acid residue arginine 14 (nucleic acids 39, 40 and 41) in DCM patients. This basic amino acid is important in maintaining the upstream consensus sequence for PKA phosphorylation of Ser 16 in PLN. To assess the function of this mutant PLN, we introduced the PLN-R14Del in cardiac myocytes of the PLN null mouse. Transgenic lines expressing mutant PLN-R14Del at similar protein levels to wild types exhibited no inhibition of the initial rates of oxalate-facilitated SR Ca uptake compared to PLN-knockouts (PLN-KO). The contractile parameters and Ca-kinetics also remained highly stimulated in PLN-R14Del cardiomyocytes, similar to PLN-KO, and isoproterenol did not further stimulate these hyper-contractile basal parameters. Consistent with the lack of inhibition on SR Ca-transport and contractility, confocal microscopy indicated that the PLN-R14Del failed to co-localize with SERCA2a. Moreover, PLN-R14Del did not co-immunoprecipitate with SERCA2a (as did WT-PLN), but rather co-immunoprecipitated with the sarcolemmal Na/K-ATPase (NKA) and stimulated NKA activity. In addition, studies in HEK cells indicated significant fluorescence resonance energy transfer between PLN-R14Del-YFP and NKAα1-CFP, but not with the NKA regulator phospholemman. Despite the enhanced cardiac function in PLN-R14Del hearts (as in PLN-knockouts), there was cardiac hypertrophy (unlike PLN-KO) coupled with activation of Akt and the MAPK pathways. Thus, human PLN-R14Del is misrouted to the sarcolemma, in the absence of endogenous PLN, and alters NKA activity, leading to cardiac remodeling.
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