Identification of Hypoxia Induced Metabolism Associated Genes in Pulmonary Hypertension.

Objective: Pulmonary hypertension (PH) associated with hypoxia and lung disease (Group 3) is the second most common form of PH and associated with increased morbidity and mortality. This study was aimed to identify hypoxia induced metabolism associated genes (MAGs) for better understanding of hypoxic PH. Methods: Rat pulmonary arterial smooth muscle cells (PASMCs) were isolated and cultured in normoxic or hypoxic condition for 24 h. Cells were harvested for liquid chromatography-mass spectrometry analysis. Functional annotation of distinguishing metabolites was performed using Metaboanalyst. Top 10 enriched metabolite sets were selected for the identification of metabolism associated genes (MAGs) with a relevance score >8 in Genecards. Transcriptomic data from lungs of hypoxic PH in mice/rats or of PH patients were accessed from Gene Expression Omnibus (GEO) database or open-access online platform. Connectivity Map analysis was performed to identify potential compounds to reverse the metabolism associated gene profile under hypoxia stress. The construction and module analysis of the protein-protein interaction (PPI) network was performed. Hub genes were then identified and used to generate LASSO model to determine its accuracy to predict occurrence of PH. Results: A total of 36 altered metabolites and 1,259 unique MAGs were identified in rat PASMCs under hypoxia. 38 differentially expressed MAGs in mouse lungs of hypoxic PH were revealed, with enrichment in multi-pathways including regulation of glucose metabolic process, which might be reversed by drugs such as blebbistatin. 5 differentially expressed MAGs were displayed in SMCs of Sugen 5416/hypoxia induced PH rats at the single cell resolution. Furthermore, 6 hub genes (Cat, Ephx1, Gpx3, Gstm4, Gstm5, and Gsto1) out of 42 unique hypoxia induced MAGs were identified. Higher Cat, Ephx1 and lower Gsto1 were displayed in mouse lungs under hypoxia (all p < 0.05), in consistent with the alteration in lungs of PH patients. The hub gene-based LASSO model can predict the occurrence of PH (AUC = 0.90). Conclusion: Our findings revealed six hypoxia-induced metabolism associated hub genes, and shed some light on the molecular mechanism and therapeutic targets in hypoxic PH.

Corrigendum: Identification of Hypoxia Induced Metabolism Associated Genes in Pulmonary Hypertension.

[This corrects the article DOI: 10.3389/fphar.2021.753727.].

DNA methyltransferase 3B deficiency unveils a new pathological mechanism of pulmonary hypertension.

DNA methylation plays critical roles in vascular pathology of pulmonary hypertension (PH). The underlying mechanism, however, remains undetermined. Here, we demonstrate that global DNA methylation was elevated in the lungs of PH rat models after monocrotaline administration or hypobaric hypoxia exposure. We showed that DNA methyltransferase 3B (DNMT3B) was up-regulated in both PH patients and rodent models. Furthermore, Dnmt3b -/- rats exhibited more severe pulmonary vascular remodeling. Consistently, inhibition of DNMT3B promoted proliferation/migration of pulmonary artery smooth muscle cells (PASMCs) in response to platelet-derived growth factor-BB (PDGF-BB). In contrast, overexpressing DNMT3B in PASMCs attenuated PDGF-BB-induced proliferation/migration and ameliorated hypoxia-mediated PH and right ventricular hypertrophy in mice. We also showed that DNMT3B transcriptionally regulated inflammatory pathways. Our results reveal that DNMT3B is a previously undefined mediator in the pathogenesis of PH, which couples epigenetic regulations with vascular remodeling and represents a therapeutic target to tackle PH.

The features of rare pathogenic BMPR2 variants in pulmonary arterial hypertension: Comparison between patients and reference population.

BACKGROUND: Mutations in the gene encoding bone morphogenetic protein receptor type 2 (BMPR2) are the most common genetic risk factors underlying pulmonary arterial hypertension (PAH). However, the features of PAH-related BMPR2 rare variants remain unclear. We propose that the discrepancy of BMPR2 rare variants landscape between patients with PAH and reference population would be important to address the genetic background of PAH-related variants. METHODS: We genotyped BMPR2 rare variants in 670 Chinese patients with pulmonary arterial hypertension. The BMPR2 rare variants were screened in 10,508 reference people from two exome databases. RESULTS: The prevalence of rare BMPR2 variants in patients with PAH was significantly higher compared to the reference population (21.5%, 144/670 vs 0.87%, 91/10508, p = 1.3 × 10-118). In patients with PAH, 49% of identified BMPR2 rare variants were loss-of-function or splicing. These BMPR2 rare variants were only observed in 1% of the reference population (p = 9.0 × 10-12). Arg491, which is absent in the reference population, represented as hot-spot site (14.6%, 21/144) in PAH patients. BMPR2 missense mutations in PAH patients were more likely distributed in extracellular ligand-binding domain (ECD, 29.7% vs 11.1%, p < 0.001). Compared with Non-PAH-related variations, PAH-related missense variants tend to alter the amino acid electric status (51.4% vs 23.3%, p < 0.001). CONCLUSIONS: BMPR2 variants located in extracellular ligand-binding domain or altered the amino acid electric status are more pathogenic.

Spermine promotes pulmonary vascular remodelling and its synthase is a therapeutic target for pulmonary arterial hypertension.

Pathological mechanisms of pulmonary arterial hypertension (PAH) remain largely unexplored. Effective treatment of PAH remains a challenge. The aim of this study was to discover the underlying mechanism of PAH through functional metabolomics and to help develop new strategies for prevention and treatment of PAH.Metabolomic profiling of plasma in patients with idiopathic PAH was evaluated through high-performance liquid chromatography mass spectrometry, with spermine identified to be the most significant and validated in another independent cohort. The roles of spermine and spermine synthase were examined in pulmonary arterial smooth muscle cells (PASMCs) and rodent models of pulmonary hypertension.Using targeted metabolomics, plasma spermine levels were found to be higher in patients with idiopathic PAH compared to healthy controls. Spermine administration promoted proliferation and migration of PASMCs and exacerbated vascular remodelling in rodent models of pulmonary hypertension. The spermine-mediated deteriorative effect can be attributed to a corresponding upregulation of its synthase in the pathological process. Inhibition of spermine synthase in vitro suppressed platelet-derived growth factor-BB-mediated proliferation of PASMCs, and in vivo attenuated monocrotaline-mediated pulmonary hypertension in rats.Plasma spermine promotes pulmonary vascular remodelling. Inhibiting spermine synthesis could be a therapeutic strategy for PAH.

Association of Rare PTGIS Variants With Susceptibility and Pulmonary Vascular Response in Patients With Idiopathic Pulmonary Arterial Hypertension.

Importance: Idiopathic pulmonary arterial hypertension (IPAH) is a fatal disease with high heritability; however, the bone morphogenetic protein receptor 2 (BMPR2) gene only accounts for 17% of IPAH. The genetic basis of IPAH needs further investigation. Objective: To identify novel IPAH susceptibility genes other than BMPR2. Design, Setting, and Participants: This 2-stage, case-control genetic association study enrolled 230 patients with IPAH from 2 referral pulmonary hypertension centers in China. Eligible patients had no BMPR2 variants and were compared with 968 healthy control participants. Data were collected from January 1, 2000, to July 31, 2015, and analyzed from August 1, 2015, to May 30, 2018. Exposures: PTGIS rare variants. Main Outcomes and Measures: Whole-genome sequencing was performed to identify putative IPAH genes in a discovery cohort, with validation in an independent referral cohort. Correlation of genotype and hemodynamic characteristics was then evaluated at baseline and after pulmonary vasodilator testing. Functional assessments were conducted to analyze the effects of identified genetic variants on transcript splicing, enzymatic activity, and endothelial cell phenotypes. Results: Among 230 patients with IPAH (164 female [71.3%]; mean [SD] age, 34 [18] years), an enrichment of rare variants in a gene encoding prostacyclin synthase (PTGIS) was identified in the discovery cohort. The association of PTGIS rare variants with IPAH was confirmed in the replication cohort. In the combined data set, PTGIS rare variants were found in 14 of 230 cases (6.1%) and 8 of 968 controls (0.8%) (odds ratio, 7.8; 95% CI, 3.2-18.8; P = 5 × 10-6, logistic regression). Compared with patients without PTGIS variants, inhaled iloprost induced a more significant decrease of pulmonary vascular resistance (difference in the least square mean, -21.7%; 95% CI, -31.4% to -12.0%; P < .001, linear regression model) and an increase of cardiac index (difference in the least square mean, 18.3%; 95% CI, 8.8%-27.8%; P < .001, linear regression model) in patients with PTGIS variants. The minigene assay indicated that the c.521 + 1G>A variant resulted in aberrant messenger RNA transcripts. The functional studies showed that the 2 missense rare variants (R252Q and A447T) resulted in a decrease in prostacyclin production and increased cell death of pulmonary microvascular endothelial cells. Conclusions and Relevance: This study identified 3 rare loss-of-function variants in the PTGIS gene from 2 independent cohorts with IPAH. The genetic variants of PTGIS predispose pulmonary vascular responses to the iloprost stimulation. These findings suggest that PTGIS variants may be involved in the pathogenesis of IPAH.

Circulating Plasma Metabolomic Profiles Differentiate Rodent Models of Pulmonary Hypertension and Idiopathic Pulmonary Arterial Hypertension Patients.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a severe progressive disease with systemic metabolic dysregulation. Monocrotaline (MCT)-induced and hypoxia-induced pulmonary hypertension (PH) rodent models are the most widely used preclinical models, however, whether or not these preclinical models recapitulate metabolomic profiles of PAH patients remain unclear. METHODS: In this study, a targeted metabolomics panel of 126 small molecule metabolites was conducted. We applied it to the plasma of the 2 preclinical rodent models of PH and 30 idiopathic pulmonary arterial hypertension (IPAH) patients as well as 30 healthy controls to comparatively assess the metabolomic profiles of PAH patients and rodent models. RESULTS: Significantly different metabolomics profiling and pathways were shown among the 2 classical rodent models and IPAH patients. Pathway analysis demonstrated that methionine metabolism and urea cycle metabolism were the most significant pathway involved in the pathogenesis of hypoxia-induced PH model and MCT-induced model, respectively, and both of them were also observed in the dysregulated pathways in IPAH patients. CONCLUSIONS: These 2 models may develop PAH through different metabolomic pathways and each of the 2 classical PH model resembles IPAH patients in certain aspects.

Association of interleukin-6 and interleukin-10 expression, gene polymorphisms, and Takayasu arteritis in a Chinese Han population.

Takayasu arteritis (TA) is a chronic inflammatory disease. Interleukin (IL)-6 and IL-10 are important cytokines involved in the immune response of TA in some ethnicities. We investigated whether the single-nucleotide polymorphism (SNP) of IL-6 and IL-10 genes and their expressions were associated with TA in a Chinese Han population. One hundred eighty-four TA patients and 235 healthy controls (HC) were recruited. DNA and RNA were extracted from peripheral blood cells. Genotyping of IL-6 and -10 was performed using polymerase chain reaction-ligase detection reaction (PCR-LDR). The mRNA levels of IL-6 and IL-10 were semi-quantified using reverse transcription polymerase chain reaction (RT-PCR) and real-time polymerase chain reaction (real-time PCR). Plasma levels of them were examined by enzyme-linked immunosorbent assay (ELISA). The mRNA levels of IL-6 in active phase of TA were higher than those in stable phase (p = 0.015); the IL-10 in active phase was lower compared with stable phase (p = 0.046). Plasma levels of IL-6 in TA were higher than those in HC (p = 0.024). Plasma levels of IL-10 showed no difference between the two groups (p = 0.264). Plasma levels of IL-6 in active phase were increased than those in stable phase (p = 0.043) while those of IL-10 were decreased in active phase (p = 0.041). We found no significant differences between TA and HC in the frequency of any of the variations in the SNPs of IL-6 and IL-10 genes. The expression levels of both cytokines were associated with the disease status, indicating that they may serve as potential biomarkers for monitoring disease activity.

Germline BMP9 mutation causes idiopathic pulmonary arterial hypertension.

BACKGROUND: Idiopathic pulmonary arterial hypertension (IPAH) is a rare disease with high heritability. Although several predisposing genes have been linked to IPAH, the genetic aetiology remains unknown for a large number of IPAH cases. METHODS: We conducted an exome-wide gene-based burden analysis on two independent case-control studies, including a total of 331 IPAH cases and 10 508 controls. Functional assessments were conducted to analyse the effects of genetic mutations on protein biosynthesis and function. RESULTS: The gene encoding human bone morphogenetic protein 9 (BMP9) was identified as a novel genetic locus displaying exome-wide association with IPAH in the discovery cohort (OR 18.8; p=1.9×10-11). This association was authenticated in the independent replication cohort (p=1.0×10-5). Collectively, the rare coding mutations in BMP9 occurred in 6.7% of cases, ranking this gene second to BMPR2, comprising a combined significance of 2.7×10-19 (OR 21.2). Intriguingly, the patients with BMP9 mutations had lower plasma levels of BMP9 than those without. Functional studies showed that the BMP9 mutations led to reduced BMP9 secretion and impaired anti-apoptosis ability in pulmonary arterial endothelial cells. CONCLUSION: We identify BMP9 as an IPAH culprit gene.

Inhibition of CRTH2-mediated Th2 activation attenuates pulmonary hypertension in mice.

Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by progressive pulmonary artery (PA) remodeling. T helper 2 cell (Th2) immune response is involved in PA remodeling during PAH progression. Here, we found that CRTH2 (chemoattractant receptor homologous molecule expressed on Th2 cell) expression was up-regulated in circulating CD3+CD4+ T cells in patients with idiopathic PAH and in rodent PAH models. CRTH2 disruption dramatically ameliorated PA remodeling and pulmonary hypertension in different PAH mouse models. CRTH2 deficiency suppressed Th2 activation, including IL-4 and IL-13 secretion. Both CRTH2+/+ bone marrow reconstitution and CRTH2+/+ CD4+ T cell adoptive transfer deteriorated hypoxia + ovalbumin-induced PAH in CRTH2-/- mice, which was reversed by dual neutralization of IL-4 and IL-13. CRTH2 inhibition alleviated established PAH in mice by repressing Th2 activity. In culture, CRTH2 activation in Th2 cells promoted pulmonary arterial smooth muscle cell proliferation through activation of STAT6. These results demonstrate the critical role of CRTH2-mediated Th2 response in PAH pathogenesis and highlight the CRTH2 receptor as a potential therapeutic target for PAH.

Metabolic reprogramming of the urea cycle pathway in experimental pulmonary arterial hypertension rats induced by monocrotaline.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a rare systemic disorder associated with considerable metabolic dysfunction. Although enormous metabolomic studies on PAH have been emerging, research remains lacking on metabolic reprogramming in experimental PAH models. We aim to evaluate the metabolic changes in PAH and provide new insight into endogenous metabolic disorders of PAH. METHOD: A single subcutaneous injection of monocrotaline (MCT) (60 mg kg- 1) was used for rats to establish PAH model. Hemodynamics and right ventricular hypertrophy were adopted to evaluate the successful establishment of PAH model. Plasma samples were assessed through targeted metabolomic profiling platform to quantify 126 endogenous metabolites. Orthogonal partial least squares discriminant analysis (OPLS-DA) was used to discriminate between MCT-treated model and control groups. Metabolite Set Enrichment Analysis was adapted to exploit the most disturbed metabolic pathways. RESULTS: Endogenous metabolites of MCT treated PAH model and control group were well profiled using this platform. A total of 13 plasma metabolites were significantly altered between the two groups. Metabolite Set Enrichment Analysis highlighted that a disruption in the urea cycle pathway may contribute to PAH onset. Moreover, five novel potential biomarkers in the urea cycle, adenosine monophosphate, urea, 4-hydroxy-proline, ornithine, N-acetylornithine, and two candidate biomarkers, namely, O-acetylcarnitine and betaine, were found to be highly correlated with PAH. CONCLUSION: The present study suggests a new role of urea cycle disruption in the pathogenesis of PAH. We also found five urea cycle related biomarkers and another two candidate biomarkers to facilitate early diagnosis of PAH in metabolomic profile.

Whole-exome sequencing improves genetic testing accuracy in pulmonary artery hypertension.

Sanger sequencing, the traditional "gold standard" for mutation detection, has been wildly used in genetic testing of pulmonary artery hypertension (PAH). However, with the advent of whole-exome sequencing (WES), few studies have compared the accuracy of WES and Sanger sequencing in routine genetic testing of PAH. PAH individuals were enrolled from Fu Wai Hospital and Shanghai Pulmonary Hospital. WES was used to analyze DNA samples from 120 PAH patients whose bone morphogenetic protein receptor type 2 (BMPR2) mutation statuses had been previously studied using Sanger sequencing. The Sanger sequencing and WES agreement was 98.3% (118/120) with near-perfect agreement (κ coefficient = 0.848). There was no significant difference between the two methods on the McNemar-Bowker test ( P > 0.05). Twenty-one BMPR2 mutation carriers and 99 non-carriers were detected by Sanger sequencing. Among the 21 BMPR2 carriers detected by Sanger sequencing, one variant (c.1040 T > A) was not found by WES. Among the 99 BMPR2 non-carriers, WES detected an extra mutation carrier (c.76 + 1 G > C) missed by Sanger sequencing. Both false-positive and false-negative results were highly conserved and were re-analyzed by Sanger sequencing. WES improved the accuracy of Sanger sequencing and detected 1% (1/99) false-positive and 4.8% (1/21) false-negative results of Sanger sequencing. No false-positive and false-negative results of WES were identified in our analysis. WES is non-inferior to Sanger sequencing and may play a more important role in genetic testing of PAH patients in the future.

Acute Iloprost Inhalation Improves Right Ventricle Function in Pulmonary Artery Hypertension: A Cardiac Magnetic Resonance Study.

Background: Right ventricle (RV) function is among the most important prognostic factors for pulmonary arterial hypertension (PAH) patients. Inhaled iloprost, an inhaled member of the prostacyclin family, is effective for the treatment of severe PAH and acute RV failure. However, the acute effects of iloprost on RV physiology have not been thoroughly explored in the past. Materials and Methods: This prospective study involved 69 incident PAH patients, including 23 idiopathic PAH (IPAH) patients, 26 patients with PAH associated with connective tissue disease (CTD-PAH) and 20 with PAH associated with congenital heart disease (CHD-PAH). All patients underwent both right heart catheterization and cardiac magnetic resonance imaging at baseline and 20 min after 5 µg iloprost inhalation. Results: Acute iloprost inhalation reduced PVR from 13 ± 7 to 10 ± 6 Wood U (P < 0.001), increased RV ejection fraction (RVEF) from 31 ± 11 to 35 ± 12 % (P < 0.001), increased RV stroke volume from 53 ± 21 to 57 ± 22 ml (P < 0.001) and decreased RV end-diastolic volume from 179 ± 67 to 172 ± 69 ml (P < 0.001). Acute iloprost inhalation-induced RVEF improvement was correlated with the degree of PVR reduction (P < 0.001) in IPAH patients, but not in CTD-PAH or CHD-PAH patients. Conclusion: Acute iloprost inhalation improved RVEF, RV stroke volume and decreased RV volume in IPAH and CTD-PAH patients. Iloprost-induced RVEF increase was proportional to PVR reduction in IPAH patients, but not in CTD-PAH or CHD-PAH patients.

Overexpression of Cardiac-Specific Kinase TNNI3K Promotes Mouse Embryonic Stem Cells Differentiation into Cardiomyocytes.

Backgroud/Aims: The biological function of cardiac troponin I-interacting kinase (TNNI3K), a cardiac-specific functional kinase, is largely unknown. We investigated the effect of human TNNI3K (hTNNI3K) on the differentiation of mouse embryonic stem cells (mESCs) into cardiomyocytes. METHODS: First, the time-space expression of endogenous Tnni3k was detected by real-time polymerase chain reaction (PCR) and western blotting at 16 different time-points over a period of 28 days. Further, action potentials and calcium current with/without 5 µM nifedipine were measured by patch clamp for mESC-derived cardiomyocytes. HTNNI3K and mouse-derived siRNA were transfected into mESC using lentivirus vector to induce hTNNI3K overexpression and knock-down, respectively. RESULTS: The number of troponin-T (cTnT) positive cells was greater in the group with TNNI3K overexpression as compared to that in control group, while less such cells were detected in the mTnni3k knock-down group as evaluated on flow cytometry (FCM) and ImageXpress Micro system. After upregulation of connexin43, cardiac troponin-I (Ctni), Ctni, Gata4 were detected in mESCs with TNNI3K overexpression; however, overexpression of α-Actinin and Mlc2v was not detected. Interestingly, Ctnt, connexin40 and connexin45, the markers of ventricular, atrial, and pacemaker cells, respectively, were detected in by real-time PCR in TNNI3K overexpression group. CONCLUSION: our study indicated that TNNI3K overexpression promoted mESC differentiating into beating cardiomyocytes and induced up-regulating expression of cTnT by PKCε signal pathway, which suggested a modulation of TNNI3K activity as a potential therapeutic approach for ischemic cardiac disease.

Increased levels of plasma CXC-Chemokine Ligand 10, 12 and 16 are associated with right ventricular function in patients with idiopathic pulmonary arterial hypertension.

OBJECTIVE: To investigate plasma levels of CXC-Chemokine Ligand 10 (CXCL10), CXC-Chemokine Ligand 12 (CXCL12) and CXC-Chemokine Ligand 16 (CXCL16) in patients with idiopathic pulmonary arterial hypertension (IPAH). METHODS: Plasma levels of biomarkers were measured by enzyme-linked immunosorbent assay in 61 patients with IPAH and 20 healthy volunteers. RESULTS: Plasma CXCL10, CXCL12 and CXCL16 concentrations were increased significantly in IPAH patients compared with controls, and significantly correlated with N-terminal pro-brain natriuretic peptide, tricuspid annulus plane systolic excursion and right ventricular ejection fraction. CONCLUSIONS: Increased levels of CXCL10, CXCL12 and CXCL16 are associated with right ventricular dysfunction in patients with IPAH.

Elevated plasma YKL-40 as a prognostic indicator in patients with idiopathic pulmonary arterial hypertension.

BACKGROUND AND OBJECTIVE: Pulmonary vascular remodelling and inflammation have been implicated in pulmonary arterial hypertension (PAH). YKL-40, a marker of tissue remodelling and inflammation, has recently been recognized as a risk predictor of cardiovascular and inflammatory diseases. The study aimed to investigate a potential role of YKL-40 in predicting prognosis in idiopathic PAH (IPAH). METHODS: Plasma YKL-40 levels were measured in 82 IPAH patients without current or previous PAH-specific treatment during right heart catheterization and in 54 healthy volunteers. Concurrent data included clinical, haemodynamic and biochemical variables. RESULTS: Plasma YKL-40 levels were increased in IPAH patients compared with control subjects (median, interquartile range: IPAH: 24.90, 17.68-39.78 ng/mL; controls: 16.58, 14.20-19.64 ng/mL; P < 0.001). YKL-40 levels correlated with cardiac index (r = -0.244, P = 0.027) and N-terminal pro-brain natriuretic peptide (NT-proBNP, r = 0.263, P = 0.017). After a median follow-up of 578 days, YKL-40 outperformed NT-proBNP, uric acid, and 6-min walk distance in receiver operating characteristic (ROC) analyses in predicting both clinical worsening (area under the curve (AUC) 0.681) and death (AUC 0.717). Compared with patients with YKL-40 below the ROC-derived cut-off point (24.5 ng/mL), the high YKL-40 group showed higher pulmonary vascular resistance and serum uric acid levels, and showed more clinical worsening events and deaths in Kaplan-Meier analyses. Plasma YKL-40 was independently associated with clinical worsening in univariate and multivariate Cox analyses (all P < 0.05). CONCLUSIONS: Plasma YKL-40 might serve as a promising indicator of disease severity and prognosis in patients with IPAH.

Inhibitory effect of iron on in vitro proliferation of smooth muscle cells.

BACKGROUND: Iron is a biocorrodible metal that might be used in bioabsorbable stents. This study investigated the effects at the cellular and protein levels of soluble divalent iron (ferrous gluconate) and soluble trivalent iron (ferric chloride) on the proliferation of human aortic smooth muscle cell (HASMC) in vitro. METHODS: The water-soluble tetrazolium (WST-1) test was used to evaluate the effect of iron on proliferation of HASMC and Western blotting was used to measure the levels of signaling proteins involved in proliferative and apoptosis pathways. RESULTS: HASMC proliferation was inhibited in a concentration dependent manner after treatment with soluble divalent and trivalent iron at concentrations of 100-500 µmol/L. Western blotting analysis showed that the proliferating cell nuclear antigen (PCNA) expression following treatment with soluble divalent iron and trivalent iron at 100, 300 and 500 µmol/L was reduced compared to the control. The PCNA expression decreased with increasing iron concentration and to a greater extent with the trivalent iron than with the divalent iron treatment group. The p53 expression was markedly increased in a concentration dependent manner in both iron treatment groups. CONCLUSION: The soluble divalent iron and, to a greater degree trivalent iron, inhibited HASMC proliferation in a dosedependent manner, which may be attributed to reduction of PCNA expression and increase of p53 expression.

TNNI3K is a novel mediator of myofilament function and phosphorylates cardiac troponin I.

The phosphorylation of cardiac troponin I (cTnI) plays an important role in the contractile dysfunction associated with heart failure. Human cardiac troponin I-interacting kinase (TNNI3K) is a novel cardiac-specific functional kinase that can bind to cTnI in a yeast two-hybrid screen. The purpose of this study was to investigate whether TNNI3K can phosphorylate cTnI at specific sites and to examine whether the phosphorylation of cTnI caused by TNNI3K can regulate cardiac myofilament contractile function. Co-immunoprecipitation was performed to confirm that TNNI3K could interact with cTnI. Kinase assays further indicated that TNNI3K did not phosphorylate cTnI at Ser23/24 and Ser44, but directly phosphorylated Ser43 and Thr143 in vitro. The results obtained for adult rat cardiomyocytes also indicated that enhanced phosphorylation of cTnI at Ser43 and Thr143 correlated with rTNNI3K (rat TNNI3K) overexpression, and phosphorylation was reduced when rTNNI3K was knocked down. To determine the contractile function modulated by TNNI3K-mediated phosphorylation of cTnI, cardiomyocyte contraction was studied in adult rat ventricular myocytes. The contraction of cardiomyocytes increased with rTNNI3K overexpression and decreased with rTNNI3K knockdown. We conclude that TNNI3K may be a novel mediator of cTnI phosphorylation and contribute to the regulation of cardiac myofilament contraction function.

TNNI3K is a novel mediator of myofilament function and phosphorylates cardiac troponin I

The phosphorylation of cardiac troponin I (cTnI) plays an important role in the contractile dysfunction associated with heart failure. Human cardiac troponin I-interacting kinase (TNNI3K) is a novel cardiac-specific functional kinase that can bind to cTnI in a yeast two-hybrid screen. The purpose of this study was to investigate whether TNNI3K can phosphorylate cTnI at specific sites and to examine whether the phosphorylation of cTnI caused by TNNI3K can regulate cardiac myofilament contractile function. Co-immunoprecipitation was performed to confirm that TNNI3K could interact with cTnI. Kinase assays further indicated that TNNI3K did not phosphorylate cTnI at Ser23/24 and Ser44, but directly phosphorylated Ser43 and Thr143 in vitro. The results obtained for adult rat cardiomyocytes also indicated that enhanced phosphorylation of cTnI at Ser43 and Thr143 correlated with rTNNI3K (rat TNNI3K) overexpression, and phosphorylation was reduced when rTNNI3K was knocked down. To determine the contractile function modulated by TNNI3K-mediated phosphorylation of cTnI, cardiomyocyte contraction was studied in adult rat ventricular myocytes. The contraction of cardiomyocytes increased with rTNNI3K overexpression and decreased with rTNNI3K knockdown. We conclude that TNNI3K may be a novel mediator of cTnI phosphorylation and contribute to the regulation of cardiac myofilament contraction function.

Dicycloplatin differentially inhibits proliferation of human aortic smooth muscle and endothelial cells: potential for use in drug-eluting stents.

BACKGROUND: Dicycloplatin is a relatively safe third generation platinum-complex anti-cancer drug. The present study focused on the effects of dicycloplatin on in vitro proliferation and apoptosis of human aortic smooth muscle cells (HASMC) and human aortic endothelial cells (HAEC). METHODS: Proliferation of HASMC and HAEC, DNA content, and cellular levels of proliferation- and apoptosis-related proteins were assessed using the (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS) assay, flow cytometry and Western blotting assays, respectively. RESULTS: Dicycloplatin at 10 ng/ml significantly inhibited HASMC proliferation, however, 10 µg/ml were required to significantly inhibit HAEC proliferation. Cell cycle analysis showed that dicycloplatin was a non-specific inhibitor of the cell cycle. Although dicycloplatin significantly decreased proliferating cell nuclear antigen (PCNA) expression in HASMC at all concentrations tested, it did not significantly affect PCNA expression in HAEC; Bax and p53 protein expression was upregulated in dicycloplatin groups. CONCLUSIONS: Dicycloplatin at nanogram concentrations significantly inhibits HASMC proliferation, although the effect is relatively weaker than that of sirolimus. In contrast, the effect of dicycloplatin on inhibition of HAEC proliferation is much less pronounced than that on HASMC. The latter characteristics point to the potential for use of dicycloplatin in drug-eluting stents.