Michael Kapiloff, Postdoctoral Faculty Sponsor
Background: The Ca2+/calmodulin-dependent phosphatase calcineurin is a key regulator of cardiac myocyte hypertrophy in disease. An unexplained paradox is how the Abeta isoform of calcineurin (CaNAbeta) is required for induction of pathological myocyte hypertrophy, despite calcineurin Aalpha expression in the same cells. In addition, it is unclear how the pleiotropic second messenger Ca2+ drives excitation-contraction coupling, while not stimulating hypertrophy via calcineurin in the normal heart. Elucidation of the mechanisms conferring this selectively in calcineurin signaling should reveal new strategies for targeting the phosphatase in disease. Methods: Primary adult rat ventricular myocytes were studied for morphology and intracellular signaling. New Forster Resonance Energy Transfer (FRET) reporters were used to assay Ca2+ and calcineurin activity in living cells. Conditional gene deletion and adeno-associated virus (AAV)-mediated gene delivery in the mouse were used to study calcineurin signaling following transverse aortic constriction in vivo. Results: Cdc42-interacting protein (CIP4/TRIP10) was identified as a new polyproline domain-dependent scaffold for CaNAbeta2 by yeast-2-hybrid screen. Cardiac myocyte-specific CIP4 gene deletion in mice attenuated pressure overload-induced pathological cardiac remodeling and heart failure. Accordingly, blockade of CaNAbeta polyproline-dependent anchoring using a competing peptide inhibited concentric hypertrophy in cultured myocytes, while disruption of anchoring in vivo using an AAV gene therapy vector inhibited cardiac hypertrophy and improved systolic function after pressure overload. Live cell FRET biosensor imaging of cultured myocytes revealed that Ca2+ levels and calcineurin activity associated with the CIP4 compartment were increased by neurohormonal stimulation, but minimally by pacing. Conversely, Ca2+ levels and calcineurin activity detected by non-localized FRET sensors were induced by pacing and minimally by neurohormonal stimulation, providing functional evidence for differential intracellular compartmentation of Ca2+ and calcineurin signal transduction. Conclusions: These results support a structural model for Ca2+ and CaNAbeta compartmentation in cells based upon an isoform-specific mechanism for calcineurin protein-protein interaction and localization. This mechanism provides an explanation for the specific role of CaNAbeta in hypertrophy and its selective activation under conditions of pathologic stress. Disruption of CaNAbeta polyproline-dependent anchoring constitutes a rational strategy for therapeutic targeting of CaNAbeta-specific signaling responsible for pathological cardiac remodeling in cardiovascular disease deserving of further pre-clinical investigation.
View details for DOI 10.1161/CIRCULATIONAHA.119.044893
View details for PubMedID 32611257
Although aortic regurgitation (AR) is a clinically important condition that is becoming increasingly common, few relevant murine models and mechanistic studies exist for this condition. In this study, we attempted to delineate the pathological and molecular changes and address the roles of some potentially relevant molecules in an animal model of surgically induced AR.AR was induced by puncturing the aortic valve leaflets in C57BL/6J mice under echocardiographic guidance.As early as 1 week following AR, the left ventricles (LV) displayed marked impairments in diastolic function and coronary flow reserve (CFR), as well as cardiac hypertrophy and chamber dilatation at both end-systole and end-diastole. LV free wall thickening and cardiomyocyte hypertrophy in LV were observed 2 weeks following of AR while a decline in ejection fraction was not seen until after 4 weeks. Nppa (natriuretic peptide A) and Nppb (natriuretic peptide B) increased over time, in conjunction with prominent Akt activation as well as slight CaMKII (Ca2+/calmodulin-dependent protein kinase II) activation and biphasic changes in ?-arrestin-2 expression. Treatment of AR mice with Akt inhibition exacerbated the eccentric hypertrophy, while neither inhibition of CaMKII nor ?-arrestin-2 overexpression influenced the response to AR.Our structural, functional, molecular and therapeutic analyses reveal that Akt, but not CaMKII or ?-arrestin-2, plays a regulatory role in the development of LV remodeling after AR in Mice. These results may shed important light on therapeutic targets for volume overloaded cardiomyopathy.
View details for DOI 10.21037/atm.2020.01.51
View details for PubMedID 32309366
View details for PubMedCentralID PMC7154424
The intercalated disc (ID), a highly organized adhesion structure connecting neighboring cardiomyocytes, fulfills mechanical and electrical signaling communication to ensure normal heart function. Lipoprotein receptor-related protein 6 (LRP6) is a co-receptor inducing canonical Wnt/beta-catenin signaling. It was recently reported that LRP6 deficiency in cardiomyocytes predisposes to arrhythmia independent of Wnt signaling. However, whether LRP6 directly regulates the structure of IDs requires further investigation. The aim of the present study was to explore the role of LRP6 in IDs and the potential underlying mechanisms by inducible cardiac-specific LRP6 knockout mice. The results revealed that LRP6 was predominately expressed in the cell membrane, including the IDs of cardiomyocytes. Tamoxifen-inducible cardiac-specific LRP6 knockout mice displayed overt cardiac dysfunction and disruption of ID structure. Further analysis revealed that cardiac LRP6 deficiency induced the imbalance of ID component proteins, characterized by the sharply decreased expression of connexin 43 (Cx43) and the significantly increased expression of N-cadherin, desmoplakin and gamma-catenin in tissue lysates or membrane fraction from the left ventricle. STRING database analysis indicated that beta-catenin, but no other ID-associated proteins, interacted with LRP6. Our immunoprecipitation analysis demonstrated that LRP6 strongly interacted with Cx43, N-cadherin and gamma-catenin, and weakly interacted with beta-catenin, while there was no association with desmoplakin. In response to LRP6 deficiency, the recruitment of beta- or gamma-catenin to N-cadherin was increased, but they displayed little interaction with Cx43. In conclusion, LRP6 is required to maintain the integrity of ID structure and the balance of ID proteins, and the interaction between LRP6 and Cx43, N-cadherin and gamma-catenin may be involved in this process.
View details for DOI 10.1111/gtc.12727
View details for PubMedID 31609038
We recently reported low-density lipoprotein receptor-related protein 6 (LRP6) decreased in dilated cardiomyopathy hearts, and cardiac-specific knockout mice displayed lethal heart failure through activation of dynamin-related protein 1 (Drp1). We also observed lipid accumulation in LRP6 deficiency hearts, but the detailed molecular mechanisms are unclear. Here, we detected fatty acids components in LRP6 deficiency hearts and explored the potential molecular mechanisms. Fatty acid analysis by GC-FID/MS revealed cardiac-specific LRP6 knockout induced the higher level of total fatty acids and some medium-long-chain fatty acids (C16:0, C18:1n9 and C18:2n6) than in control hearts. Carnitine palmitoyltransferase 1b (CPT1b), a rate-limiting enzyme of mitochondrial ?-oxidation in adult heart, was sharply decreased in LRP6 deficiency hearts, coincident with the activation of Drp1. Drp1 inhibitor greatly improved cardiac dysfunction and attenuated the increase in total fatty acids and fatty acids C16:0, C18:1n9 in LRP6 deficiency hearts. It also greatly inhibited the decrease in the cardiac expression of CPT1b and the transcriptional factors CCCTC-binding factor (CTCF) and c-Myc induced by cardiac-specific LRP6 knockout in mice. C-Myc but not CTCF was identified to regulate CPT1b expression and lipid accumulation in cardiomyocytes in vitro. The present study indicated cardiac-specific LRP6 knockout induced lipid accumulation by Drp1/CPT1b pathway in adult mice, and c-Myc is involved in the process. It suggests that LRP6 regulates fatty acid metabolism in adult heart.
View details for DOI 10.1007/s00441-019-03126-3
View details for PubMedID 31811407
By employing a proteomic analysis on supernatant of mechanically stretched cardiomyocytes, we found that stretch induced a significantly high level of ?-2 microglobulin (?2M), a non-glycosylated protein, which is related to inflammatory diseases but rarely known in cardiovascular diseases. The present data showed that serum ?2M level was increased in patients with hypertension and further increased in patients with chronic heart failure (HF) as compared with control group, and the high level of serum ?2M level correlated to cardiac dysfunction in these patients. In pressure overload mice model by transverse aortic constriction (TAC), ?2M levels in serum and heart tissue increased progressively in a time-dependent manner. Exogenous ?2M showed pro-fibrotic effects in cultured cardiac fibroblasts but few effects in cardiomyocytes. Adeno-associated virus 9 (AAV9)-mediated knockdown of ?2M significantly reduced cardiac ?2M level and inhibited myocardial fibrosis and cardiac dysfunction but not cardiac hypertrophy at 4 weeks after TAC. In vitro, mechanical stretch induced the rapid secretion of ?2M mainly from cardiomyocytes by activation of extracellular-regulated protein kinase (ERK). Conditional medium (CM) from mechanically stretched cardiomyocytes activated cultured cardiac fibroblasts, and the effect was partly abolished by CM from ?2M-knockdown cardiomyocytes. In vivo, knockdown of ?2M inhibited the increase in phosphorylation of epidermal growth factor receptor (EGFR) induced by TAC. In cultured cardiac fibroblasts, inhibition of EGFR significantly attenuated the ?2M-induced the activation of EGFR and pro-fibrotic responses. The present study suggests that ?2M is a paracrine pro-fibrotic mediator and associated with cardiac dysfunction in response to pressure overload.
View details for DOI 10.1042/CS20180486
View details for Web of Science ID 000443728700009
View details for PubMedID 30072448
We aimed to study urotensin II (UII) in acute myocardial infarction (AMI) patients before and after percutaneous coronary intervention (PCI) and to investigate its interaction with angiotensin II (ATII) in post-AMI myocardial remodeling. In this clinical study, 63 AMI patients and 66 controls were included. Levels of UII, ATII, and NT-B-type natriuretic peptide (NT-BNP) were determined. Participants were followed up for 2 years to observe clinical outcomes. In cell biology experiments, ATII and UII were added into cardiomyocytes and fibroblasts individually or in combination. Effects of ATII and UII on cardiac hypertrophy and fibrosis were observed. UII levels increased significantly after AMI (P < 0.001), especially after PCI (P = 0.0009), and was an independent predictor of death (OR 0.007, P = 0.005). UII correlated negatively with hypertension risk stratifications (P = 0.047) and the number of coronary artery lesions (P = 0.029), whereas it correlated positively with left ventricular ejection fraction (P = 0.0395). Myocardial ERK phosphorylations (P = 0.0041) were promoted and the expressions of cardiac hypertrophy-related genes (BNP, ANP) were upregulated in cells treated with ATII and UII (P < 0.005). The ATII+UII group also had significant increases of matrix metalloproteinase-2 (MMP-2), metalloproteinase-9 (MMP9), and fibronectin expressions, as well as collagen type I, III, MMP2, and MMP9 gene transcriptions (all P < 0.05). The UII level rose in AMI and was a predictor of death, but at the right concentration it may also have a cardioprotective role. Our findings suggest that UII and ATII have synergistic effects on cardiomyocyte remodeling. UII may play a role in the myocardial healing process post-AMI.
View details for Web of Science ID 000449193400001
View details for PubMedID 30265851
Lipoprotein receptor-related protein 6 (LRP6) binds to Wnt ligands to transduce signal by stabilization of ?-catenin, which has been involved in the regulation of embryonic development and metabolism et al. Here, we observed LRP6 decreased in human hearts with dilated cardiomyopathy (DCM), and it also decreased in cultured cardiomyocytes under glucose- deprivation (GD). Knockdown of LRP6 greatly inhibited cell viability in cardiomyocytes under GD, but it didn't induce the effect in cardiomyocytes at baseline. Overexpression of LRP6 increased the cell viability in GD-cardiomyocytes. To explore potential molecular mechanisms, we detected the phosphorylation of dynamin-related protein 1(Drp1) and active ?-catenin in cardiomyocytes under GD. Knockdown of LRP6 enhanced p-Drp1(S616) level while it didn't alter the p-Drp1(S637) and active ?-catenin level in GD-cardiomyocytes. Drp1 inhibitor significantly suppressed the increase in p-Drp1 at S616 and improved the cell viability in GD-cardiomyocytes with knockdown of LRP6. Further analysis showed that knockdown of LRP6 also increased the phosphorylation of mammalian target of rapamycin (mTOR), and Drp1 inhibitor greatly inhibited the increase in p-mTOR level in GD-cardiomyocytes. The present study indicated that knockdown of LRP6 inhibited the cell viability by activation of Drp1 in GD-cardiomyocytes, and the phosphorylation of mTOR may be involved in the process. It suggests that LRP6 can prevent cardiomyocytes from death in nutrition-deprived condition.
View details for DOI 10.1016/j.biopha.2018.04.134
View details for Web of Science ID 000433328800166
View details for PubMedID 29864925
Left ventricular hypertrophy (LVH) is causally related to increased morbidity and mortality following acute myocardial infarction (AMI) via still unknown mechanisms. Although rapamycin exerts cardioprotective effects against myocardial ischemia/reperfusion (MI/R) injury in normal animals, whether rapamycin-elicited cardioprotection is altered in the presence of LVH has yet to be determined. Pressure overload induced cardiac hypertrophied mice and sham-operated controls were exposed to AMI by coronary artery ligation, and treated with vehicle or rapamycin 10 min before reperfusion. Rapamycin produced marked cardioprotection in normal control mice, whereas pressure overload induced cardiac hypertrophied mice manifested enhanced myocardial injury, and was refractory to rapamycin-elicited cardioprotection evidenced by augmented infarct size, aggravated cardiomyocyte apoptosis, and worsening cardiac function. Rapamycin alleviated MI/R injury via ERK-dependent antioxidative pathways in normal mice, whereas cardiac hypertrophied mice manifested markedly exacerbated oxidative/nitrative stress after MI/R evidenced by the increased iNOS/gp91phox expression, superoxide production, total NO metabolites, and nitrotyrosine content. Moreover, scavenging superoxide or peroxynitrite by selective gp91phox assembly inhibitor gp91ds-tat or ONOO- scavenger EUK134 markedly ameliorated MI/R injury, as shown by reduced myocardial oxidative/nitrative stress, alleviated myocardial infarction, hindered cardiomyocyte apoptosis, and improved cardiac function in aortic-banded mice. However, no additional cardioprotective effects were achieved when we combined rapamycin and gp91ds-tat or EUK134 in ischemic/reperfused hearts with or without LVH. These results suggest that cardiac hypertrophy attenuated rapamycin-induced cardioprotection by increasing oxidative/nitrative stress and scavenging superoxide/peroxynitrite protects the hypertrophied heart from MI/R.
View details for DOI 10.1042/CS20171471
View details for Web of Science ID 000427982800009
View details for PubMedID 29175946
Low density lipoprotein receptor-related protein 6 (LRP6), a wnt co-receptor, regulates multiple functions in various organs. However, the roles of LRP6 in the adult heart are not well understood. Methods: We observed LRP6 expression in heart with end-stage dilated cardiomyopathy (DCM) by western blot. Tamoxifen-inducible cardiac-specific LRP6 knockout mouse was constructed. Hemodynamic and echocardiographic analyses were performed to these mice. Results: Cardiac LRP6 expression was dramatically decreased in patients with end-stage dilated cardiomyopathy (DCM) compared to control group. Tamoxifen-inducible cardiac-specific LRP6 knockout mice developed acute heart failure and mitochondrial dysfunction with reduced survival. Proteomic analysis suggests the fatty acid metabolism disorder involving peroxisome proliferator-activated receptors (PPARs) signaling in the LRP6 deficient heart. Accumulation of mitochondrial targeting to autophagosomes and lipid droplet were observed in LRP6 deletion hearts. Further analysis revealed cardiac LRP6 deletion suppressed autophagic degradation and fatty acid utilization, coinciding with activation of dynamin-related protein 1 (Drp1) and downregulation of nuclear TFEB (Transcription factor EB). Injection of Mdivi-1, a Drp1 inhibitor, not only promoted nuclear translocation of TFEB, but also partially rescued autophagic degradation, improved PPARs signaling, and attenuated cardiac dysfunction induced by cardiac specific LRP6 deletion. Conclusions: Cardiac LRP6 deficiency greatly suppressed autophagic degradation and fatty acid utilization, and subsequently leads to lethal dilated cardiomyopathy and cardiac dysfunction through activation of Drp1 signaling. It suggests that heart failure progression may be attenuated by therapeutic modulation of LRP6 expression.
View details for DOI 10.7150/thno.22177
View details for Web of Science ID 000417132600003
View details for PubMedID 29344294
View details for PubMedCentralID PMC5771081
Remote ischemic preconditioning (RIPC) is one of the most powerful intrinsic cardioprotective strategies discovered so far and experimental data indicate that comorbidity may interfere with the protection by RIPC. Therefore, we investigate whether RIPC-induced cardioprotection was intact in hypercholesterolemic rat hearts exposed to ischemia reperfusion in vivo. Normal or hypercholesterolemic rat hearts were exposed to 30?min of ischemia and 2?h of reperfusion, with or without RIPC, PI3K inhibitor wortmannin, MEK-ERK1/2 inhibitor PD98059, GSK3? inhibitor SB216763. Infarct size, apoptosis, MG53, PI3K-p85, p-Akt, p-ERK1/2, p-GSK3?, and cleaved Caspase-3 were determined. RIPC reduced infarct size, limited cardiomyocyte apoptosis following IR that was blocked by wortmannin but not PD98059. RIPC triggered unique cardioprotective signaling including MG53, phosphorylation of Akt, and glycogen synthase kinase-3ß (GSK3?) in concert with reduced proapoptotic active caspase-3. In contrast, RIPC failed to reduce myocardial necrosis and apoptosis as well as to increase the phosphorylated Akt and GSK3? in hypercholestorolemic myocardium. Importantly, we found that inhibition of GSK with SB216763 reduced myocardial infarct size in healthy and hypercholesterolemic hearts, but no additional cardioprotective effect was achieved when combined with RIPC. Our results suggest that acute GSK3? inhibition may provide a novel therapeutic strategy for hypercholesterolemic patients during acute myocardial infarction, whereas RIPC is less effective due to signaling events that adversely affect GSK3?.
View details for DOI 10.1097/SHK.0000000000000737
View details for Web of Science ID 000395517400015
View details for PubMedID 27559699
Ryanodine receptor type 2 (RyR-2), the main Ca2+ release channel from sarcoplasmic reticulum in cardiomyocytes, plays a vital role in the regulation ofmyocardial contractile function and cardiac hypertrophy. However, the role of RyR-2 in cardiac fibrosis during the development of cardiac hypertrophy remains unclear.In this study, we examined whether RyR-2 regulates TGF?1, which is secreted from cardiomyocytes and exerts on cardiac fibrosis using cultured cardiomyocytes and cardiac fibroblasts of neonatal rats. The expression of RyR-2 was found only in cardiomyocytesbut not in cardiac fibroblasts. Mechanical stretch induced upregulation of TGF?1 in cardiomyocytes and RyR-2 knockdown significantly suppressed the upregulation of TGF?1 expression. The transcript levels of collagen genes were also decreased in fibroblasts compare with wild type, although the expression of both two kinds was higher than those in stationary cardiomyocytes (non-stretch). With the inhibition of the TGF?1-neutralizing antibody, the expression of collagen genes has no significant difference between the mechanically stretched cardiomyocytes and non-stretchedones. These results indicate that RyR-2 regulated TGF?1 expression in mechanically stretched cardiomyocytes and TGF?1 promoted collagen formation of cardiac fibroblasts by a paracrine mechanism.RyR-2 in mechanical stretch could promote the development of cardiac fibrosis involving TGF?1-dependent paracrine mechanism. Our findings provided more insight into comprehensively understanding the molecular role of RyR-2 in regulating cardiac fibrosis.
View details for DOI 10.1536/ihj.16-572
View details for PubMedID 29162778
Angiotensin II (AngII) type 1 receptor blockers (ARBs) have been effectively used in hypertension and cardiac remodeling. However, the differences among them are still unclear. We designed this study to examine and compare the effects of several ARBs widely used in clinics, including Olmesartan, Candesartan, Telmisartan, Losartan, Valsartan and Irbesartan, on the ACE-AngII-AT1 axis and the ACE2-Ang(1-7)-Mas axis during the development of cardiac remodeling after pressure overload. Although all of the six ARBs, attenuated the development of cardiac hypertrophy and heart failure induced by transverse aortic constriction (TAC) for 2 or 4weeks in the wild-type mice evaluated by echocardiography and hemodynamic measurements, the degree of attenuation by Olmesartan, Candesartan and Losartan tended to be larger than that of the other three drugs tested. Additionally, the degree of downregulation of the ACE-AngII-AT1 axis and upregulation of the ACE2-Ang(1-7)-Mas axis was higher in response to Olmesartan, Candesartan and Losartan administration in vivo and in vitro. Moreover, in angiotensinogen-knockdown mice, TAC-induced cardiac hypertrophy and heart failure were inhibited by Olmesartan, Candesartan and Losartan but not by Telmisartan, Valsartan and Irbesartan administration. Furthermore, only Olmesartan and Candesartan could downregulate the ACE-AngII-AT1 axis and upregulate the ACE2-Ang(1-7)-Mas axis in vitro. Our data suggest that Olmesartan, Candesartan and Losartan could effectively inhibit pressure overload-induced cardiac remodeling even when with knockdown of Ang II, possibly through upregulation of the expression of the ACE2-Ang(1-7)-Mas axis and downregulation of the expression of the ACE-AngII-AT1 axis. In contrast, Telmisartan, Valsartan and Irbesartan only played a role in the presence of AngII, and Losartan had no effect in the presence of AngII in vitro.
View details for DOI 10.1016/j.yjmcc.2016.05.012
View details for Web of Science ID 000382800100020
View details for PubMedID 27210827
To investigate whether nucleosome assembly protein 1-like 1 (Nap1l1) regulates the proliferation of induced pluripotent stem cells (iPSC) and the potential mechanisms.Nap1l1-knockdown-iPSC and Nap1l1-overexpression-iPSC were constructed by transfection of lentiviral particles. The proliferation of iPSC was detected by MTT analysis, and cell cycle was analyzed by flow cytometry.Nap1l1 overexpression promoted iPSC proliferation and induced G2/M transition compared to their control iPSC while Nap1l1-knockdown-iPSC dramatically displayed the reduced proliferation and accumulated G2/M phase cells. Further analysis showed that Nap1l1 overexpression in iPSC increased the expression of cyclin B1, downregulated the expression of p21 and p27, while knockdown of Nap1l1 showed the opposite effects. In addition, overexpression of Nap1l1 promoted the phosphorylation of AKT and ERK in iPSC, while knockdown of Nap1l1 inhibited the effects. However, these effects displayed in Nap1l1-overexpression-iPSC were greatly suppressed by the inhibition of AKT or ERK signaling.The results indicate that Nap1l1 promotes the proliferation of iPSC attributable to G2/M transition caused by downregulation of p27 and p21, and upregulation of cyclin B1, the activation of AKT or ERK is involved in the process. The present study has revealed a novel molecular mechanism involved in the proliferation of iPSC.
View details for DOI 10.1159/000438634
View details for Web of Science ID 000369329600031
View details for PubMedID 26824453
We previously showed that Qiliqiangxin (QL) capsules could ameliorate cardiac hypertrophy and remodeling in a mouse model of pressure overload. Here, we compared the effects of QL alone with those of QL combined with the following 3 types of antihypertensive drugs on cardiac remodeling and dysfunction induced by pressure overload for 4 weeks in mice: an angiotensin II type 1 receptor (AT1-R) blocker (ARB), an angiotensin-converting enzyme inhibitor (ACEI), and a ?-adrenergic receptor (?-AR) blocker (BB). Adult male mice (C57B/L6) were subjected to either transverse aortic constriction or sham operation for 4 weeks, and the drugs (or saline) were orally administered through gastric tubes. Cardiac function and remodeling were evaluated through echocardiography, catheterization, histology, and analysis of hypertrophic gene expression. Cardiomyocyte apoptosis and autophagy, AT1-R and ?1-AR expression, and cell proliferation-related molecules were also examined. Although pressure overload-induced cardiac remodeling and dysfunction, hypertrophic gene reprogramming, AT1-R and ?1-AR expression, and ERK phosphorylation were significantly attenuated by QL alone, QL + ARB, QL + ACEI, and QL + BB, the attenuation was stronger in the combination treatment groups. Moreover, apoptosis was reduced to a larger extent by each combination treatment than by QL alone, whereas autophagy was more strongly attenuated by either QL + ARB or QL + ACEI. None of the treatments significantly upregulated ErbB2 or ErbB4 phosphorylation, and none significantly downregulated C/EBP? expression. Therefore, the effects of QL on chronic pressure overload-induced cardiac remodeling may be significantly increased when QL is combined with an ARB, an ACEI, or a BB.
View details for DOI 10.1097/FJC.0000000000000230
View details for Web of Science ID 000356370300017
View details for PubMedID 25806688
View details for PubMedCentralID PMC4461387
Plasma urotensin II (UII) has been observed to be raised in patients with acute myocardial infarction; suggesting a possible cardiac protective role for this peptide. However, the molecular mechanism is unclear. Here, we treated cultured cardiomyocytes with H2O2 to induce oxidative stress; observed the effect of UII on H2O2-induced apoptosis and explored potential mechanisms. UII pretreatment significantly reduced the number of apoptotic cardiomyocytes induced by H2O2; and it partly abolished the increase of pro-apoptotic protein Bax and the decrease of anti-apoptotic protein Bcl-2 in cardiomyocytes induced by H2O2. SiRNA targeted to the urotensin II receptor (UT) greatly inhibited these effects. Further analysis revealed that UII increased the production of hydrogen sulfide (H2S) and the level of cystathionine-?-lyase (CSE) by activating the ERK signaling in H2O2-treated-cardiomyocytes. Si-CSE or ERK inhibitor not only greatly inhibited the increase in CSE level or the phosphorylation of ERK induced by UII but also reversed anti-apoptosis of UII in H2O2-treated-cadiomyocytes. In conclusion, UII rapidly promoted the phosphorylation of ERK and upregulated CSE level and H2S production, which in turn activated ERK signaling to protect cardiomyocytes from apoptosis under oxidative stress. These results suggest that increased plasma UII level may protect cardiomyocytes at the early-phase of acute myocardial infarction in patients.
View details for DOI 10.3390/ijms160612482
View details for Web of Science ID 000357492800040
View details for PubMedID 26047336
View details for PubMedCentralID PMC4490456
Cardiac side population cells (CSPs) are promising cell resource for the regeneration in diseased heart as intrinsic cardiac stem cells. However, the relative low ratio of CSPs in the heart limited the ability of CSPs to repair heart and improve cardiac function effectively under pathophysiological condition. Which factors limiting the proliferation of CSPs in diseased heart are unclear. Here, we show that urotensin II (UII) regulates the proliferation of CSPs by c-Jun N-terminal kinase (JNK) and low density lipoprotein receptor-related protein 6 (LRP6) signalling during pressure overload. Pressure overload greatly upregulated UII level in plasma, UII receptor (UT) antagonist, urantide, promoted CSPs proliferation and improved cardiac dysfunction during chronic pressure overload. In cultured CSPs subjected to mechanical stretch (MS), UII significantly inhibited the proliferation by UT. Nanofluidic proteomic immunoassay showed that it is the JNK activation, but not the extracellular signal-regulated kinase signalling, that involved in the UII-inhibited- proliferation of CSPs during pressure overload. Further analysis in vitro indicated UII-induced-phospho-JNK regulates phosphorylation of LRP6 in cultured CSPs after MS, which is important in the inhibitory effect of UII on the CSPs during pressure overload. In conclusion, UII inhibited the proliferation of CSPs by JNK/LRP6 signalling during pressure overload. Pharmacological inhibition of UII promotes CSPs proliferation in mice, offering a possible therapeutic approach for cardiac failure induced by pressure overload.
View details for DOI 10.1111/jcmm.12230
View details for Web of Science ID 000335861500011
View details for PubMedID 24447593
View details for PubMedCentralID PMC4119391