Novel combinations of variations in KCNQ1 were associated with patients with long QT syndrome or Jervell and Lange-Nielsen syndrome.

OBJECTIVES: Long QT syndrome (LQTS) is one of the primary causes of sudden cardiac death (SCD) in youth. Studies have identified mutations in ion channel genes as key players in the pathogenesis of LQTS. However, the specific etiology in individual families remains unknown. METHODS: Three unrelated Chinese pedigrees diagnosed with LQTS or Jervell and Lange-Nielsen syndrome (JLNS) were recruited clinically. Whole exome sequencing (WES) was performed and further validated by multiplex ligation-dependent probe amplification (MLPA) and Sanger sequencing. RESULTS: All of the probands in our study experienced syncope episodes and featured typically prolonged QTc-intervals. Two probands also presented with congenital hearing loss and iron-deficiency anemia and thus were diagnosed with JLNS. A total of five different variants in KCNQ1, encoding a subunit of the voltage-gated potassium channel, were identified in 3 probands. The heterozygous variants, KCNQ1 c.749T > C was responsible for LQTS in Case 1, transmitting in an autosomal dominant pattern. Two patterns of compound heterozygous variants were responsible for JLNS, including a large deletion causing loss of the exon 16 and missense variant c.1663 C > T in Case 2, and splicing variant c.605-2 A > G and frame-shift variant c.1265del in Case 3. To our knowledge, the compound heterozygous mutations containing a large deletion and missense variant were first reported in patients with JLNS. CONCLUSION: Our study expanded the LQTS genetic spectrum, thus favoring disease screening and diagnosis, personalized treatment, and genetic consultation.

Next-generation sequencing identified novel Desmoplakin frame-shift variant in patients with Arrhythmogenic cardiomyopathy.

BACKGROUND: Arrhythmogenic cardiomyopathy (AC) is one of the leading causes for sudden cardiac death (SCD). Recent studies have identified mutations in cardiac desmosomes as key players in the pathogenesis of AC. However, the specific etiology in individual families remains largely unknown. METHODS: A 4-generation family presenting with syncope, lethal ventricular arrhythmia and SCD was recruited. Targeted next generation sequencing (NGS) was performed and validated by Sanger sequencing. Plasmids containing the mutation and wild type (WT) were constructed. Real-time PCR, western-blot and immunofluorescence were performed to detect the functional change due to the mutation. RESULTS: The proband, a 56-year-old female, presented with recurrent palpitations and syncope. An ICD was implanted due to her family history of SCD/ aborted SCD. NGS revealed a novel heterozygous frame-shift variant (c.832delG) in Desmoplakin (DSP) among 5 family members. The variant led to frame-shift and premature termination, producing a truncated protein. Cardiac magnetic resonance (CMR) of the family members carrying the same variant shown myocardium thinning and fatty infiltration in the right ventricular, positive bi-ventricular late gadolinium enhancement and severe RV dysfunction, fulfilling the diagnostic criteria of AC. HEK293T cells transfected with mutant plasmids expressed truncated DSP mRNA and protein, upregulation of nuclear junction plakoglobin (JUP) and downregulation of ß-catenin, when compared with WT. CONCLUSION: We infer that the novel c.832delG variant in DSP was associated with AC in this family, likely through Wnt/ß-catenin signaling pathway.

Characterization of viral genomic mutations in novel influenza A (H7N9)-infected patients: the association between oseltamivir-resistant variants and viral shedding duration.

Since February 2013, human infections with the novel influenza A H7N9 virus have occurred in eastern China. It is important to detect mutations in viral genes and analyze the clinical features of patients and viral shedding duration related to neuraminidase inhibitor (NAI) resistance. We collected clinical specimens from 31 hospitalized H7N9 patients and sequenced NA, PB2, HA, and M gene fragments. Of the 31 identified patients, 7 (22.6%) carried the R292K substitution in NA, 30 (96.8%), 3 (9.7%), and 5 (16.1%) carried E627K, Q591K, and D701N mutations in PB2, respectively, and 2 (6.5%) carried both E627K and D701N mutations in PB2. All 26 identified patients harbored Q226L mutations and possessed only a single arginine (R) at cleavage sites in the HA and a S31N mutation in M2. Among 7 NA-R292K mutated patients, 3 died and 4 were discharged. There was no significant difference in the days that patients started oseltamivir treatment after symptom onset between NA-R292K mutant and NA-R292 wild-type patients (median days, 7 vs 6, P = 0.374). NA-R292K mutant patients had a significantly longer duration of viral shedding than NA-R292 wild-type patients after oseltamivir treatment (median days, 10 vs 5, P = 0.022). The mutation of R292K in NA conferring the potential ability of oseltamivir resistance resulted in prolonged viral duration and poor outcome and should be taken into consideration in the clinical management of infected patients.

Serum Circulating miR-150 is a Predictor of Post-Acute Myocardial Infarction Heart Failure.

Patients with ischemic heart disease are associated with poor prognosis, and their number has increased globally. Therefore, biomarkers that could predict post-acute myocardial infarction (AMI) heart failure (HF) would be helpful to guide appropriate treatment. Based on the diagnosis on admission and results of echocardiogram performed on admission and 1 year after discharge, the current study recruited 54 patients with post-AMI HF, 59 patients with post-AMI non-HF, and 59 healthy controls. Eight candidate microRNAs (miRs) were screened through real-time quantitative PCR. Serum circulating miR-150 level in the post-AMI HF group was significantly lower than the post-AMI non-HF group (0.4 ± 0.3 versus 0.7 ± 0.3, P < 0.001). Further analysis showed that serum circulating miR-150 level was associated with ejection fraction (EF) 1 year after discharge (P < 0.001). Receiver operating characteristic curve (ROC) analysis found that area under the ROC (AUC) was 0.616 (95%CI = 0.511-0.721, P = 0.034) when BNP was used to predict post-AMI HF, whereas AUC improved to 0.764 (95%CI = 0.674-0.855, P < 0.001) when miR-150 was used. The combination of BNP and miR-150 significantly improved the AUC to 0.807 (95%CI = 0.727-0.886, P < 0.001). Finally, multivariate logistic regression analysis revealed that either LVEF on admission or serum circulating miR-150 level was independently associated with post-AMI HF. Serum circulating miR-150 is a novel biomarker to predict post-AMI HF. Further large sample prospective clinical research is needed to validate its role in the future.

Changes of circulating Th22 cells in children with hand, foot, and mouth disease caused by enterovirus 71 infection.

Interleukin (IL)-22+CD4+T (Th22) cells play crucial roles in the pathogenesis of autoimmune diseases and infectious diseases, although the role of Th22 cells remains largely unclear in children with hand, foot, and mouth disease (HFMD) caused by enterovirus 71 (EV71). This study aims to explore the role of circulating IL-22+IL-17A-CD4+T (cTh22) cells in children with EV71-associated HFMD. We found that during the acute stage of illness, the frequencies of cTh22 and circulating IL-22+IL-17A+CD4+T (IL-22+cTh17) cells in CD4+T cells infrom affected patients, and especially in severely affected patients, were significantly higher than in healthy controls (HC). The major source of IL-22 production was cTh22 cells, partially from cTh17 cells. Moreover, the protein and mRNA levels of IL-22, IL-17A, IL-23, IL-6, and TNF-α were significantly different among the mild patients, severe patients and HC, as well as AHR and RORγt mRNA levels. A positive correlation was found between plasma IL-22 levels and cTh22 cell frequencies, and cTh17 cell and IL-22+ cTh17 cell frequencies. Furthermore, the frequencies of cTh22 were significantly decreased in the convalescent patients. Our findings indicated that cTh22 cells could play critical roles in the pathogenesis of EV71 infection, and are potential therapeutic targets for patients with EV71-associated HFMD.

Simultaneous detection of influenza A subtypes of H3N2 virus, pandemic (H1N1) 2009 virus and reassortant avian H7N9 virus in humans by multiplex one-step real-time RT-PCR assay.

BACKGROUND: Influenza A virus is a leading causative pathogen of human acute respiratory infection. Recently, the co-circulation of pandemic (H1N1) 2009 and seasonal H3N2 viruses was reported, and sporadic cases with reassortant avian H7N9 virus are continually reported in China. We aimed to establish a multiplex one-step real-time reverse transcription-polymerase chain reaction (rRT-PCR) assay to simultaneously detect and discriminate FluA subtypes, including human seasonal H3N2 virus, pandemic (H1N1) 2009 virus and reassortant avian H7N9 virus, in one reaction tube. METHODS: Clinical samples, including throat swabs and sputum, were collected from the patients with influenza-like illness (ILIs). Total viral RNA from each sample or viral culture was extracted, and the specific detection of FluA virus and its subtypes was performed using a multiplex rRT-PCR assay. RESULTS: The limitation of detection (LOD) of the multiplex assay was 5.4 × 10-2 50% tissue culture infective dose (TCID50) per reaction or 4.8 × 101 copies per reaction for each virus of the three viruses. For simultaneously detecting the three viruses, the LOD was 1.8 × 10-2 TCID50 per reaction or 1.6 × 10 copies per reaction for testing the total FluA virus RNA and 5.6 × 10-2 TCID50 per reaction or 5.1 × 10 copies per reaction for the H3, H1, and H7 genes in one reaction tube. The multiplex assay specifically detected these viruses, and no cross-reaction with other pathogens was found. Moreover, the assay had reliable clinical sensitivity (100%) and valuable clinical specificity (>95%). The detection of FluA with the matrix (M) gene contributed to the further determination of these subtypes, and the Rnase P gene (RP) was considered an internal control to favourably evaluate the quality of the clinical samples. CONCLUSIONS: These findings indicate that the multiplex assay can simultaneously detect and discriminate FluA subtypes with reliable sensitivity and specificity, which is required for the early clinical diagnosis and viral surveillance of patients with FluA infection.

Common miR-590 Variant rs6971711 Present Only in African Americans Reduces miR-590 Biogenesis.

MicroRNAs (miRNAs) are recognized as important regulators of cardiac development, hypertrophy and fibrosis. Recent studies have demonstrated that genetic variations which cause alterations in miRNA:target interactions can lead to disease. We hypothesized that genetic variations in miRNAs that regulate cardiac hypertrophy/fibrosis might be involved in generation of the cardiac phenotype in patients diagnosed with hypertrophic cardiomyopathy (HCM). To investigate this question, we Sanger sequenced 18 miRNA genes previously implicated in myocyte hypertrophy/fibrosis and apoptosis, using genomic DNA isolated from the leukocytes of 199 HCM patients. We identified a single nucleotide polymorphism (rs6971711, C57T SNP) at the 17th position of mature miR-590-3p (= 57th position of pre-miR-590) that is common in individuals of African ancestry. SNP frequency was higher in African American HCM patients (n = 55) than ethnically-matched controls (n = 100), but the difference was not statistically significant (8.2% vs. 6.5%; p = 0.5). Using a cell culture system, we discovered that presence of this SNP resulted in markedly lower levels of mature miR-590-5p (39 ± 16%, p<0.003) and miR-590-3p (20 ± 2%, p<0.003), when compared with wild-type (WT) miR-590, without affecting levels of pri-miR-590 and pre-miR-590. Consistent with this finding, the SNP resulted in reduced target suppression when compared to WT miR-590 (71% suppression by WT vs 60% suppression by SNP, p<0.03). Since miR-590 can regulate TGF-ß, Activin A and Akt signaling, SNP-induced reduction in miR-590 biogenesis could influence cardiac phenotype by de-repression of these signaling pathways. Since the SNP is only present in African Americans, population studies in this patient population would be valuable to investigate effects of this SNP on myocyte function and cardiac physiology.

Characterization of endonuclease G and mitochondria-sarcoplasmic reticulum-related proteins during cardiac hypertrophy.

Endonuclease G (Endo G) is a novel determinant of cardiac hypertrophy. Here, we report the characterization of Endo G and mitochondria-sarcoplasmic reticulum-related proteins during cardiac hypertrophy, and hypothesize that Endo G regulate mitochondrial function partly through Mfn2 and Jp2 during cardiac hypertrophy. Our results show that Endo G levels gradually increased at the beginning of phenylephrine-induced cardiac hypertrophy, accompanied by an abnormal mitochondrial membrane potential. The up-regulation of Mfn2, Jp2, and Endo G appeared at an early stage of cardiac hypertrophy, whereas PGC1α was not up-regulated until a later stage. Abolishing Endo G with siRNA led to the uncoupling of the mitochondrial electron transport chain from ATP production and decreased PGC1α expression, likely by affecting the juxtaposition of the mitochondria and the sarcoplasmic reticulum via Mfn2 and Jp2. Furthermore, abolishing Jp2 altered the expression of Endo G expression and induced mitochondrial dysfunction, suggesting that mitochondrial abnormalities in cardiac hypertrophy are most likely caused by Endo G. Taken together, our study established a link between Endo G and mitochondrial function during cardiac hypertrophy, partly through the effects of Endo G on Mfn2 and Jp2, and revealed a role for Endo G in the crosstalk between the processes controlled by Mfn2 and Jp2 in maladaptive cardiac hypertrophy.

Detection of a novel avian influenza A (H7N9) virus in humans by multiplex one-step real-time RT-PCR assay.

BACKGROUND: A novel avian influenza A (H7N9) virus emerged in eastern China in February 2013. 413 confirmed human cases, including 157 deaths, have been recorded as of July 31, 2014. METHODS: Clinical specimens, including throat swabs, sputum or tracheal aspirates, etc., were obtained from patients exhibiting influenza-like illness (ILIs), especially from those having pneumonia and a history of occupational exposure to poultry and wild birds. RNA was extracted from these samples and a multiplex one-step real-time RT-PCR assay was developed to specifically detect the influenza A virus (FluA). PCR primers targeted the conserved M and Rnase P (RP) genes, as well as the hemagglutinin and neuraminidase genes of the H7N9 virus. RESULTS: The multiplex assay specifically detected the avian H7N9 virus, and no cross-reaction with other common respiratory pathogens was observed. The detection limit of the assay was approximately 0.05 50% tissue culture infective doses (TCID50), or 100 copies per reaction. Positive detection of the H7N9 virus in sputum/tracheal aspirates was higher than in throat swabs during the surveillance of patients with ILIs. Additionally, detection of the matrix (M) and Rnase P genes aided in the determination of the novel avian H7N9 virus and ensured the quality of the clinical samples. CONCLUSIONS: These results demonstrate that the multiplex assay detected the novel avian H7N9 virus with high specificity and sensitivity, which is essential for the early diagnosis and treatment of infected patients.

Increased frequency of circulating follicular helper T cells in children with hand, foot, and mouth disease caused by enterovirus 71 infection.

Enterovirus 71 (EV71) is a major causative agent of hand, foot, and mouth disease (HFMD) in children. The role of T follicular helper (TFH) cells in EV71-infected children remains unclear in regulating humoral immunity. The frequency of circulating ICOS(high)/PD-1(high)CXCR5(+)CD4(+) TFH cells in the children with mild and severe EV71 infection and healthy controls (HC) was detected by flow cytometry, respectively. IL-21 and IL-6 mRNA expression and their serum levels, Bcl-6 mRNA expression, and specific neutralizing antibodies against EV71 (NAb-EV71) were measured. In the acute stage of patients with EV71 infection, increased frequencies of circulating TFH cells with ICOS(high) and PD-1(high) expression in the mild and severe patients were observed, and the positive correlations among the frequencies of circulating TFH cells and the serum levels of IL-21, IL-6, and NAb-EV71 titres were detected, respectively. Moreover, the expressions of IL-6 and IL-21 mRNA in PBMCs from patients were also significantly higher than those of HC. However, further analysis did not reveal any significant differences between mild and severe patients. These data indicate a role of TFH cells and associated cytokines in modulating the humoral response during the pathogenesis of EV71 infection.

Avian-origin influenza A(H7N9) infection in influenza A(H7N9)-affected areas of China: a serological study.

Serological surveillance conducted in areas of an outbreak of influenza A(H7N9) infection in China found no seropositivity for antibodies specific for avian-origin influenza A(H7N9) among 1129 individuals of the general population, whereas >6% of 396 poultry workers were positive (on the basis of a hemagglutination inhibition titer of ≥ 80) for this subtype, confirming that infected poultry is the principal source of human infections and that subclinical infections are possible. Fourteen days after symptom onset, elevated levels of antibodies to A(H7N9) were found in 65.8% of patients (25/38) who survived but in only 28.6% of those (2/7) who died, suggesting that the presence of antibodies may improve clinical outcome in infected patients.

Prolyl hydroxylase domain protein 2 regulates the intracellular cyclic AMP level in cardiomyocytes through its interaction with phosphodiesterase 4D.

Cyclic adenosine 3',5'-monophosphate (cAMP), which is synthesized by adenylyl cyclase (AC) and degraded by phosphodiesterase (PDE), plays crucial roles in the regulation of multiple cellular functions and physiological processes. Prolyl hydroxylase domain (PHD) proteins, which belong to a family of dioxygenases that function as oxygen sensors through their hydroxylation activity, have been implicated in multiple signaling pathways. Here, we aimed to determine whether PHD played a role in regulating intracellular cAMP level in cardiomyocytes. Through the overexpression/knockdown of the PHD gene and the measurement of the cAMP content, we found that PHD2, but not PHD1 or PHD3, acts as a regulator of intracellular cAMP. In neonatal rat cardiomyocytes and H9c2 cells, the overexpression of PHD2 increased the intracellular cAMP level, whereas the PHD2 knockdown reduced it. There was no alteration in the AC expression or activity in cells that overexpressed or downregulated PHD2. The overexpression of PHD2 decreased both the protein expression and the activity of phosphodiesterase 4D (PDE4D), whereas the PHD2 knockdown increased the PDE4D expression and activity. Co-immunoprecipitation experiments revealed a direct binding between PHD2 and PDE4D and liquid chromatography-tandem mass spectrometry analyses identified the specific hydroxylation sites on PDE4D. In conclusion, PHD2 may directly interact with PDE4D to function as a novel regulator of the intracellular cAMP levels in cardiomyocytes.

Prolyl hydroxylase 2: a novel regulator of ß2 -adrenoceptor internalization.

Adrenergic receptor (AR)-mediated signalling is modulated by oxygen levels. Prolyl hydroxylases (PHDs) are crucial for intracellular oxygen sensing and organism survival. However, it remains to be clarified whether or how PHDs are involved in the regulation of ß(2) -adrenoceptor (ß(2) -AR) signalling. Here we show that PHD2 can modulate the rate of ß(2) -AR internalization through interactions with ß-arrestin 2. PHD2 hydroxylates ß-arrestin 2 at the proline (Pro)(176), Pro(179) and Pro(181) sites, which retards the recruitment of ß-arrestin 2 to the plasma membrane and inhibits subsequent co-internalization with ß(2) -AR into the cytosol. ß(2) -AR internalization is critical to control the temporal and spatial aspects of ß(2) -AR signalling. Identifying novel regulators of ß(2) -AR internalization will enable us to develop new strategies to manipulate receptor signalling and provide potential targets for drug development in the prevention and treatment of diseases associated with ß(2) -AR signalling dysregulation.

Prolyl hydroxylase 3 interacts with Bcl-2 to regulate doxorubicin-induced apoptosis in H9c2 cells.

Prolyl hydroxylases (PHDs) are dioxygenases that use oxygen as a co-substrate to hydroxylate proline residues. Three PHD isoforms (PHD1, PHD2 and PHD3) have been identified in mammalian cells. PHD3 expression is upregulated in some cardiac diseases such as cardiomyopathy, myocardial ischemia-reperfusion injury and congestive heart failure, all of which are associated with apoptosis. However, the role of PHDs in cardiomyocyte apoptosis remains unknown. Here, we have found that exposure of embryonic rat heart-derived H9c2 cells to doxorubicin (DOX) induced cell apoptosis as evaluated by caspase-3/7 activity, mitochondrial membrane potential (Δψm) and cell viability, and that this apoptosis was linked to PHD3 upregulation. PHD inhibition or PHD3 silencing substantially ameliorated DOX-induced apoptosis, but PHD1 or PHD2 knockdown did not significantly influence apoptosis. Furthermore, immunoprecipitation experiments showed that PHD3 upregulation reduced the formation of the Bax-Bcl-2 complex, inhibiting the anti-apoptotic effect of Bcl-2. Thus, PHD3 upregulation may be partially responsible for DOX-induced cardiomyocyte apoptosis via its interaction with Bcl-2. Inhibition of PHD3 is likely to be cardioprotective against apoptosis in some heart disorders.

A novel GATA6 mutation in patients with tetralogy of Fallot or atrial septal defect.

GATA6 is a member of the GATA family of transcription factors, and its expression and functions overlap with those of GATA4 during heart development. Mutations in GATA4 have been related to human congenital heart diseases (CHDs) in several studies, whereas mutations in GATA6 have only recently been reported in patients with persistent truncus arteriosus. Animal experiments have revealed critical roles for GATA6 in the development of the myocardium and cardiac morphogenesis, thereby highlighting the potential involvement of GATA6 defects in the pathogenesis of CHDs. Here, we screened the GATA6 in 270 individuals with sporadic CHDs by direct sequencing. After identification of the mutation, a luciferase reporter assay and real-time quantitative polymerase chain reaction were performed to detect functional changes in the mutant transcription factor. The same heterozygous missense mutation (Ser184Asn) was identified in three patients, including one with tetralogy of Fallot and two with atrial septal defects. This mutation was not found in 500 unrelated ethnically matched healthy subjects. Direct sequencing of this region in the parents of these three patients revealed the same mutation in one of the parents for each patient, and one of the parent carriers presented with a bicuspid aortic valve. Biological analysis revealed clearly decreased transcriptional activity of GATA6 Ser184Asn in vitro. All these data suggest that GATA6 Ser184Asn is a novel mutation associated with CHDs and has an important role in disease pathogenesis.

beta2- but not beta1-adrenoceptor activation modulates intracellular oxygen availability.

beta-Adrenoceptors (beta-ARs) play a critical role in the regulation of cardiovascular function. Intracellular oxygen homeostasis is crucial for the survival of cardiomyocytes. However, it is still unclear whether beta-AR activation can modulate intracellular oxygen. Here we used mitochondrial and cytosolic target Renilla luciferase to detect intracellular oxygen concentration. Pharmacological experiments revealed that beta2-AR activation specifically regulates intracellular oxygen in cardiomyocytes and COS7 cells. This effect was abrogated by inhibitory G protein (Gi) inhibition, endothelial nitric oxide synthase (eNOS) blockade, and NO scavenging, implicating that the beta2-AR-Gi-eNOS pathway is involved in this regulation. beta2-AR activation increased the AMP/ATP ratio, AMPK activity, ROS production and prolyl hydroxylase activity. These effects also contribute to the regulation of beta2-AR signalling, thus providing an additional layer of complexity to enforce the specificity of beta1-AR and beta2-AR signalling. Collectively, the study provides novel insight into the modulation of oxygen homeostasis, broadens the scope of beta2-AR function, and may have crucial implications for beta2-AR signalling regulation.