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1.
J Am Heart Assoc ; 8(16): e012779, 2019 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-31423874

RESUMO

Background Center-based cardiac rehabilitation (CBCR) has been shown to improve outcomes in patients with heart failure (HF). Home-based cardiac rehabilitation (HBCR) can be an alternative to increase access for patients who cannot participate in CBCR. Hybrid cardiac rehabilitation (CR) combines short-term CBCR with HBCR, potentially allowing both flexibility and rigor. However, recent data comparing these initiatives have not been synthesized. Methods and Results We performed a meta-analysis to compare functional capacity and health-related quality of life (hr-QOL) outcomes in HF for (1) HBCR and usual care, (2) hybrid CR and usual care, and (3) HBCR and CBCR. A systematic search in 5 standard databases for randomized controlled trials was performed through January 31, 2019. Summary estimates were pooled using fixed- or random-effects (when I2>50%) meta-analyses. Standardized mean differences (95% CI) were used for distinct hr-QOL tools. We identified 31 randomized controlled trials with a total of 1791 HF participants. Among 18 studies that compared HBCR and usual care, participants in HBCR had improvement of peak oxygen uptake (2.39 mL/kg per minute; 95% CI, 0.28-4.49) and hr-QOL (16 studies; standardized mean difference: 0.38; 95% CI, 0.19-0.57). Nine RCTs that compared hybrid CR with usual care showed that hybrid CR had greater improvements in peak oxygen uptake (9.72 mL/kg per minute; 95% CI, 5.12-14.33) but not in hr-QOL (2 studies; standardized mean difference: 0.67; 95% CI, -0.20 to 1.54). Five studies comparing HBCR with CBCR showed similar improvements in functional capacity (0.0 mL/kg per minute; 95% CI, -1.93 to 1.92) and hr-QOL (4 studies; standardized mean difference: 0.11; 95% CI, -0.12 to 0.34). Conclusions HBCR and hybrid CR significantly improved functional capacity, but only HBCR improved hr-QOL over usual care. However, both are potential alternatives for patients who are not suitable for CBCR.

2.
Clin Cancer Res ; 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31308061

RESUMO

Purpose: Myelodysplastic syndromes (MDS) with deletion of chromosome 7q/7 [-7/(del)7q MDS] is associated with worse outcomes and needs novel insights into pathogenesis. Reduced expression of signaling protein dedicator of cytokinesis 4 (DOCK4) in patients with -7/(del)7q MDS leads to a block in hematopoietic stem cell (HSC) differentiation. Identification of targetable signaling networks downstream of DOCK4 will provide means to restore hematopoietic differentiation in MDS.Experimental design: We utilized phosphoproteomics approaches to identify signaling proteins perturbed as a result of reduced expression of DOCK4 in human HSCs and tested their functional significance in primary model systems.Results: We demonstrate that reduced levels of DOCK4 lead to increased global tyrosine phosphorylation of proteins in primary human HSCs. LYN kinase and phosphatases INPP5D (SHIP1) and PTPN6 (SHP1) displayed greatest levels of tyrosine phosphorylation when DOCK4 expression levels were reduced using DOCK4-specific siRNA. Our data also found that increased phosphorylation of SHIP1 and SHP1 phosphatases were due to LYN kinase targeting these phosphatases as substrates. Increased migration and impediment of HSC differentiation were consequences of these signaling alterations. Pharmacologic inhibition of SHP1 reversed these functional aberrations in HSCs expressing low DOCK4 levels. In addition, differentiation block seen in DOCK4 haplo-insufficient [-7/(del)7q] MDS was rescued by inhibition of SHP1 phosphatase.Conclusions: LYN kinase and phosphatases SHP1 and SHIP1 are perturbed when DOCK4 expression levels are low. Inhibition of SHP1 promotes erythroid differentiation in healthy HSCs and in -7/(del)7q MDS samples with low DOCK4 expression. Inhibitors of LYN, SHP1 and SHIP1 also abrogated increased migratory properties in HSCs expressing reduced levels of DOCK4.

5.
Nat Cell Biol ; 21(5): 640-650, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31011167

RESUMO

Spliceosome mutations are common in myelodysplastic syndromes (MDS) and acute myeloid leukaemia (AML), but the oncogenic changes due to these mutations have not been identified. Here a global analysis of exon usage in AML samples revealed distinct molecular subsets containing alternative spliced isoforms of inflammatory and immune genes. Interleukin-1 receptor-associated kinase 4 (IRAK4) was the dominant alternatively spliced isoform in MDS and AML and is characterized by a longer isoform that retains exon 4, which encodes IRAK4-long (IRAK4-L), a protein that assembles with the myddosome, results in maximal activation of nuclear factor kappa-light-chain-enhancer of B cells (NF-κB) and is essential for leukaemic cell function. Expression of IRAK4-L is mediated by mutant U2 small nuclear RNA auxiliary factor 1 (U2AF1) and is associated with oncogenic signalling in MDS and AML. Inhibition of IRAK4-L abrogates leukaemic growth, particularly in AML cells with higher expression of the IRAK4-L isoform. Collectively, mutations in U2AF1 induce expression of therapeutically targetable 'active' IRAK4 isoforms and provide a genetic link to activation of chronic innate immune signalling in MDS and AML.


Assuntos
Quinases Associadas a Receptores de Interleucina-1/genética , Leucemia Mieloide Aguda/genética , Síndromes Mielodisplásicas/genética , Fator de Processamento U2AF/genética , Processamento Alternativo/genética , Éxons/genética , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Imunidade Inata/genética , Inflamação/genética , Inflamação/patologia , Leucemia Mieloide Aguda/patologia , Masculino , Mutação/genética , Síndromes Mielodisplásicas/patologia , Isoformas de Proteínas/genética , Transdução de Sinais , Spliceossomos/genética
6.
J Clin Invest ; 130: 1612-1625, 2019 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-30702441

RESUMO

Although clear cell renal cell carcinoma (ccRCC) has been shown to result in widespread aberrant cytosine methylation and loss of 5-hydroxymethylcytosine (5hmC), the prognostic impact and therapeutic targeting of this epigenetic aberrancy has not been fully explored. Analysis of 576 primary ccRCC samples demonstrated that loss of 5hmC was strongly associated with aggressive clinicopathologic features and was an independent adverse prognostic factor. Loss of 5hmC also predicted reduced progression-free survival after resection of nonmetastatic disease. The loss of 5hmC in ccRCC was not due to mutational or transcriptional inactivation of ten eleven translocation (TET) enzymes, but to their functional inactivation by l-2-hydroxyglutarate (L2HG), which was overexpressed due to the deletion and underexpression of L2HG dehydrogenase (L2HGDH). Ascorbic acid (AA) reduced methylation and restored genome-wide 5hmC levels via TET activation. Fluorescence quenching of the recombinant TET-2 protein was unaffected by L2HG in the presence of AA. Pharmacologic AA treatment led to reduced growth of ccRCC in vitro and reduced tumor growth in vivo, with increased intratumoral 5hmC. These data demonstrate that reduced 5hmC is associated with reduced survival in ccRCC and provide a preclinical rationale for exploring the therapeutic potential of high-dose AA in ccRCC.

7.
Artigo em Inglês | MEDLINE | ID: mdl-30765295

RESUMO

Circulating plasma levels of endothelin-1 and related peptides generated during the synthesis of endothelin-1 from its precursor molecule pre-proendothelin-1 have been widely studied as potential risk markers for cardiovascular events. The associations of endothelin-1 with aging, blood pressure, lung function, and chronic kidney disease have been described, as have relations between endothelin-1 levels and evidence of cardiac remodeling, including increased left atrial diameter and increased left ventricular mass. Endothelin-1 has been studied as a predictor of and prognostic marker in coronary artery disease, myocardial infarction, and heart failure. The relationship of endothelin-1 levels to mortality in the general population has also been explored. This review examines the current state of knowledge of circulating endothelin-1 levels as they relate to cardiovascular events and prognosis, and explores future directions for research, including using endothelin-1 or related peptide levels to guide personalized treatment regimens and to select patients for primary prevention strategies.

8.
JACC Heart Fail ; 7(2): 98-108, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30704613

RESUMO

OBJECTIVE: To synthesize existing epidemiological data on cardiac dysfunction in HIV. BACKGROUND: Data on the burden and risk of human immunodeficiency virus (HIV) infection-associated cardiac dysfunction have not been adequately synthesized. We performed meta-analyses of extant literature on the frequency of several subtypes of cardiac dysfunction among people living with HIV. METHODS: We searched electronic databases and reference lists of review articles and combined the study-specific estimates using random-effects model meta-analyses. Heterogeneity was explored using subgroup analyses and meta-regressions. RESULTS: We included 63 reports from 54 studies comprising up to 125,382 adults with HIV infection and 12,655 cases of various cardiac dysfunctions. The pooled prevalence (95% confidence interval) was 12.3% (6.4% to 19.7%; 26 studies) for left ventricular systolic dysfunction (LVSD); 12.0% (7.6% to 17.2%; 17 studies) for dilated cardiomyopathy; 29.3% (22.6% to 36.5%; 20 studies) for grades I to III diastolic dysfunction; and 11.7% (8.5% to 15.3%; 11 studies) for grades II to III diastolic dysfunction. The pooled incidence and prevalence of clinical heart failure were 0.9 per 100 person-years (0.4 to 2.1 per 100 person-years; 4 studies) and 6.5% (4.4% to 9.6%; 8 studies), respectively. The combined prevalence of pulmonary hypertension and right ventricular dysfunction were 11.5% (5.5% to 19.2%; 14 studies) and 8.0% (5.2% to 11.2%; 10 studies), respectively. Significant heterogeneity was observed across studies for all the outcomes analyzed (I2 > 70%, p < 0.01), only partly explained by available study level characteristics. There was a trend for lower prevalence of LVSD in studies reporting higher antiretroviral therapy use or lower proportion of acquired immune deficiency syndrome. The prevalence of LVSD was higher in the African region. After taking into account the effect of regional variation, there was evidence of lower prevalence of LVSD in studies published more recently. CONCLUSIONS: Cardiac dysfunction is frequent in people living with HIV. Additional prospective studies are needed to better understand the burden and risk of various forms of cardiac dysfunction related to HIV and the associated mechanisms. (Cardiac dysfunction in people living with HIV-a systematic review and meta-analysis; CRD42018095374).

9.
J Am Heart Assoc ; 8(1): e010110, 2019 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-30620261

RESUMO

Background Image reconstruction thickness may impact quantitative coronary artery calcium scoring (CACS) from lung cancer screening computed tomography (LCSCT), limiting its application in practice. Methods and Results We evaluated Agatston-based quantitative CACS from 1.25-mm LCSCT and cardiac computed tomography for agreement in 87 patients. We then evaluated Agatston-based quantitative CACS from 1.25-, 2.5-, and 5.0-mm slice thickness LCSCT for agreement in 258 patients. Secondary analysis included the impact of slice thickness on predictive value of 4-year outcomes. Median age of patients who underwent 1.25-mm LCSCT and cardiac computed tomography was 63 years (interquartile interval, 57, 68). CACS from 1.25-mm LCSCT and cardiac computed tomography demonstrated a strong Pearson correlation, R=0.9770 (0.965, 0.985), with good agreement. The receiver operating characteristic curve areas under the curve for cardiac computed tomography and LCSCT were comparable at 0.8364 (0.6628, 1.01) and 0.8208 (0.6431, 0.9985), respectively ( P=0.733). Median age of patients who underwent LCSCT with 3 slice thicknesses was 66 years (interquartile interval, 63, 73). Compared with CACS from 1.25-mm scans, CACS from 2.5- and 5.0-mm scans demonstrated strong Pearson correlations, R=0.9949 (0.9935, 0.996) and R=0.9478 (0.9338, 0.959), respectively, though bias was largely negative for 5.0-mm scans. Receiver operating characteristic curve areas under the curve for 1.25-, 2.5-, and 5.0-mm scans were comparable at 0.7040 (0.6307, 0.7772), 0.7063 (0.6327, 0.7799), and 0.7194 (0.6407, 0.7887), respectively ( P=0.6487). When using individualized high-risk thresholds derived from respective receiver operating characteristic curves, all slice thicknesses demonstrated similar prognostic value. Conclusions Slice thickness is an important consideration when interpreting Agatston CACS from LCSCTs. Despite the absence of ECG gating, it appears reasonable to report CACS from either 1.25- or 2.5-mm slice thickness LCSCT to help stratify cardiovascular risk. Conversely, 5.0-mm scans largely underidentify calcium, limiting practical use within the established CACS values used to categorize cardiovascular risk.

10.
J Am Heart Assoc ; 7(18): e009729, 2018 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-30371195

RESUMO

Background Recent studies have demonstrated a continuum in clinical risk related to mean pulmonary artery pressure that begins at >19 mm Hg, which is below the traditional threshold used to define pulmonary hypertension ( PH ) of 25 mm Hg. Because of the implications on patient diagnosis and prognosis, the generalizability and validity of these data need further confirmation. Methods and Results Databases were searched from inception through January 31, 2018, to identify studies comparing all-cause mortality between patients with mildly elevated mean pulmonary artery pressure near but <25 mm Hg versus the referent group. The meta-analysis included 15 nonrandomized studies and 16 482 patients (7451 [45.2%] with measured or calculated mean pulmonary artery pressure of 19-24 mm Hg by right heart catheterization [n=6037] and echocardiography [n=1414] [mild PH ]). The mean duration of follow-up was 5.2 years. Compared with the referent group, mild PH was associated with an increased risk of mortality (risk ratio, 1.52; 95% confidence interval, 1.32-1.74; P<0.001; I2=47%). Secondary analysis using risk-adjusted time-to-event estimates showed a similar result (hazard ratio, 1.19; 95% confidence interval, 1.09-1.31; P<0.001; I2=42%). The findings were consistent between subgroups of right heart catheterization and echocardiography studies ( Pinteraction>0.05). There was evidence of publication bias; however, this did not influence the risk estimate (Duval and Tweedie's trim and fill adjusted risk ratio, 1.34; 95% confidence interval, 1.15-1.56). Conclusions The risk of mortality is increased in patients with mild PH , defined as measured or calculated mean pulmonary artery pressure >19 mm Hg. These data emphasize a need for diagnosing patients with mild PH with consideration to enrollment in PH clinical studies investigating pharmacological and nonpharmacological interventions to attenuate clinical risk and improve outcomes.

11.
J Clin Invest ; 128(12): 5479-5488, 2018 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-30252677

RESUMO

Acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) are associated with disease-initiating stem cells that are not eliminated by conventional therapies. Transcriptomic analysis of stem and progenitor populations in MDS and AML demonstrated overexpression of STAT3 that was validated in an independent cohort. STAT3 overexpression was predictive of a shorter survival and worse clinical features in a large MDS cohort. High STAT3 expression signature in MDS CD34+ cells was similar to known preleukemic gene signatures. Functionally, STAT3 inhibition by a clinical, antisense oligonucleotide, AZD9150, led to reduced viability and increased apoptosis in leukemic cell lines. AZD9150 was rapidly incorporated by primary MDS/AML stem and progenitor cells and led to increased hematopoietic differentiation. STAT3 knockdown also impaired leukemic growth in vivo and led to decreased expression of MCL1 and other oncogenic genes in malignant cells. These studies demonstrate that STAT3 is an adverse prognostic factor in MDS/AML and provide a preclinical rationale for studies using AZD9150 in these diseases.

12.
Blood ; 132(14): 1507-1518, 2018 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-30104217

RESUMO

Adult T-cell leukemia lymphoma (ATLL) is a rare T cell neoplasm that is endemic in Japanese, Caribbean, and Latin American populations. Most North American ATLL patients are of Caribbean descent and are characterized by high rates of chemo-refractory disease and worse prognosis compared with Japanese ATLL. To determine genomic differences between these 2 cohorts, we performed targeted exon sequencing on 30 North American ATLL patients and compared the results with the Japanese ATLL cases. Although the frequency of TP53 mutations was comparable, the mutation frequency in epigenetic and histone modifying genes (57%) was significantly higher, whereas the mutation frequency in JAK/STAT and T-cell receptor/NF-κB pathway genes was significantly lower. The most common type of epigenetic mutation is that affecting EP300 (20%). As a category, epigenetic mutations were associated with adverse prognosis. Dissimilarities with the Japanese cases were also revealed by RNA sequencing analysis of 9 primary patient samples. ATLL samples with a mutated EP300 gene have decreased total and acetyl p53 protein and a transcriptional signature reminiscent of p53-mutated cancers. Most importantly, decitabine has highly selective single-agent activity in the EP300-mutated ATLL samples, suggesting that decitabine treatment induces a synthetic lethal phenotype in EP300-mutated ATLL cells. In conclusion, we demonstrate that North American ATLL has a distinct genomic landscape that is characterized by frequent epigenetic mutations that are targetable preclinically with DNA methyltransferase inhibitors.

13.
Ann Am Thorac Soc ; 15(10): 1186-1196, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30011374

RESUMO

RATIONALE: Although chronic obstructive pulmonary disease has been related to heart failure, the relationship between the restrictive spirometry pattern (forced vital capacity [FVC] < 80% predicted with preserved forced expiratory volume in 1 second [FEV1]/FVC ratio) and heart failure is poorly understood. OBJECTIVES: To determine whether having a restrictive spirometry pattern is associated with incident heart failure hospitalization. METHODS: Community-dwelling African Americans from the Jackson Heart Study (total n = 5,306; analyzed n = 4,210 with spirometry and heart failure outcome data) were grouped by restrictive spirometry (FEV1/FVC ≥ 0.70, FVC < 80%; n = 840), airflow obstruction (FEV1/FVC < 0.70; n = 341), and normal spirometry (FEV1/FVC ≥ 0.70, FVC ≥ 80%; n = 3,029) at the time of baseline examination in 2000-2004. We assessed relationships of echocardiographic parameters and biomarkers with spirometry patterns using regression models. Incident heart failure was defined as an adjudicated hospitalization for heart failure after January 1, 2005 in subjects with no self-reported heart failure history. We used multivariable-adjusted Poisson regression models and Cox proportional hazards models, with death treated as a competing risk in the Cox models, to test associations between spirometry patterns and incident heart failure. We also modeled the association of FVC% predicted with heart failure hospitalization risk using a restricted cubic spline after excluding subjects with airflow obstruction. RESULTS: At the time of baseline spirometry, participants with restrictive spirometry had a median age of 57.2 years (interquartile range, 47.8-64.1); 38.1% were male. Compared with normal spirometry, restrictive spirometry was associated with a higher transmitral early (E) wave velocity to atrial (A) wave velocity ratio, higher pulmonary artery systolic pressure, and higher endothelin levels. After a median follow-up time of 8.0 years, 8.0% of subjects with restrictive spirometry (n = 67) had developed incident heart failure, compared with 3.8% of those with normal spirometry (n = 115) and 10.6% of those with airflow obstruction (n = 36). After risk adjustment, both a restrictive pattern (hazard ratio [HR], 1.5; 95% confidence interval [CI], 1.1-2.0) and airflow obstruction (HR, 1.7; 95% CI, 1.1-2.5) were associated with increased rates of incident heart failure hospitalization compared with normal spirometry. Using flexible modeling, the lowest hazards of heart failure hospitalization were observed around FVC 90-100%, with lower FVC% values associated with an increased incidence of heart failure. CONCLUSIONS: Both a restrictive pattern on spirometry and airflow obstruction identify African Americans with impaired lung health at risk for heart failure.

14.
Sensors (Basel) ; 18(6)2018 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-29890704

RESUMO

The Internet of Things (IoT) utilizes algorithms to facilitate intelligent applications across cities in the form of smart-urban projects. As the majority of devices in IoT are battery operated, their applications should be facilitated with a low-power communication setup. Such facility is possible through the Low-Power Wide-Area Network (LPWAN), but at a constrained bit rate. For long-range communication over LPWAN, several approaches and protocols are adopted. One such protocol is the Long-Range Wide Area Network (LoRaWAN), which is a media access layer protocol for long-range communication between the devices and the application servers via LPWAN gateways. However, LoRaWAN comes with fewer security features as a much-secured protocol consumes more battery because of the exorbitant computational overheads. The standard protocol fails to support end-to-end security and perfect forward secrecy while being vulnerable to the replay attack that makes LoRaWAN limited in supporting applications where security (especially end-to-end security) is important. Motivated by this, an enhanced LoRaWAN security protocol is proposed, which not only provides the basic functions of connectivity between the application server and the end device, but additionally averts these listed security issues. The proposed protocol is developed with two options, the Default Option (DO) and the Security-Enhanced Option (SEO). The protocol is validated through Burrows⁻Abadi⁻Needham (BAN) logic and the Automated Validation of Internet Security Protocols and Applications (AVISPA) tool. The proposed protocol is also analyzed for overheads through system-based and low-power device-based evaluations. Further, a case study on a smart factory-enabled parking system is considered for its practical application. The results, in terms of network latency with reliability fitting and signaling overheads, show paramount improvements and better performance for the proposed protocol compared with the two handshake options, Pre-Shared Key (PSK) and Elliptic Curve Cryptography (ECC), of Datagram Transport Layer Security (DTLS).

17.
Circ Res ; 122(6): 864-876, 2018 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-29437835

RESUMO

RATIONALE: Current methods assessing clinical risk because of exercise intolerance in patients with cardiopulmonary disease rely on a small subset of traditional variables. Alternative strategies incorporating the spectrum of factors underlying prognosis in at-risk patients may be useful clinically, but are lacking. OBJECTIVE: Use unbiased analyses to identify variables that correspond to clinical risk in patients with exercise intolerance. METHODS AND RESULTS: Data from 738 consecutive patients referred for invasive cardiopulmonary exercise testing at a single center (2011-2015) were analyzed retrospectively (derivation cohort). A correlation network of invasive cardiopulmonary exercise testing parameters was assembled using |r|>0.5. From an exercise network of 39 variables (ie, nodes) and 98 correlations (ie, edges) corresponding to P<9.5e-46 for each correlation, we focused on a subnetwork containing peak volume of oxygen consumption (pVo2) and 9 linked nodes. K-mean clustering based on these 10 variables identified 4 novel patient clusters characterized by significant differences in 44 of 45 exercise measurements (P<0.01). Compared with a probabilistic model, including 23 independent predictors of pVo2 and pVo2 itself, the network model was less redundant and identified clusters that were more distinct. Cluster assignment from the network model was predictive of subsequent clinical events. For example, a 4.3-fold (P<0.0001; 95% CI, 2.2-8.1) and 2.8-fold (P=0.0018; 95% CI, 1.5-5.2) increase in hazard for age- and pVo2-adjusted all-cause 3-year hospitalization, respectively, were observed between the highest versus lowest risk clusters. Using these data, we developed the first risk-stratification calculator for patients with exercise intolerance. When applying the risk calculator to patients in 2 independent invasive cardiopulmonary exercise testing cohorts (Boston and Graz, Austria), we observed a clinical risk profile that paralleled the derivation cohort. CONCLUSIONS: Network analyses were used to identify novel exercise groups and develop a point-of-care risk calculator. These data expand the range of useful clinical variables beyond pVo2 that predict hospitalization in patients with exercise intolerance.

18.
J Physiol ; 596(5): 827-855, 2018 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-29313986

RESUMO

KEY POINTS: Abnormal mitochondrial morphology and function in cardiomyocytes are frequently observed under persistent Gq protein-coupled receptor (Gq PCR) stimulation. Cardiac signalling mechanisms for regulating mitochondrial morphology and function under pathophysiological conditions in the heart are still poorly understood. We demonstrate that a downstream kinase of Gq PCR, protein kinase D (PKD) induces mitochondrial fragmentation via phosphorylation of dynamin-like protein 1 (DLP1), a mitochondrial fission protein. The fragmented mitochondria enhance reactive oxygen species generation and permeability transition pore opening in mitochondria, which initiate apoptotic signalling activation. This study identifies a novel PKD-specific substrate in cardiac mitochondria and uncovers the role of PKD on cardiac mitochondria, with special emphasis on the molecular mechanism(s) underlying mitochondrial injury with abnormal mitochondrial morphology under persistent Gq PCR stimulation. These findings provide new insights into the molecular basis of cardiac mitochondrial physiology and pathophysiology, linking Gq PCR signalling with the regulation of mitochondrial morphology and function. ABSTRACT: Regulation of mitochondrial morphology is crucial for the maintenance of physiological functions in many cell types including cardiomyocytes. Small and fragmented mitochondria are frequently observed in pathological conditions, but it is still unclear which cardiac signalling pathway is responsible for regulating the abnormal mitochondrial morphology in cardiomyocytes. Here we demonstrate that a downstream kinase of Gq protein-coupled receptor (Gq PCR) signalling, protein kinase D (PKD), mediates pathophysiological modifications in mitochondrial morphology and function, which consequently contribute to the activation of apoptotic signalling. We show that Gq PCR stimulation induced by α1 -adrenergic stimulation mediates mitochondrial fragmentation in a fission- and PKD-dependent manner in H9c2 cardiac myoblasts and rat neonatal cardiomyocytes. Upon Gq PCR stimulation, PKD translocates from the cytoplasm to the outer mitochondrial membrane (OMM) and phosphorylates a mitochondrial fission protein, dynamin-like protein 1 (DLP1), at S637. PKD-dependent phosphorylation of DLP1 initiates DLP1 association with the OMM, which then enhances mitochondrial fragmentation, mitochondrial superoxide generation, mitochondrial permeability transition pore opening and apoptotic signalling. Finally, we demonstrate that DLP1 phosphorylation at S637 by PKD occurs in vivo using ventricular tissues from transgenic mice with cardiac-specific overexpression of constitutively active Gαq protein. In conclusion, Gq PCR-PKD signalling induces mitochondrial fragmentation and dysfunction via PKD-dependent DLP1 phosphorylation in cardiomyocytes. This study is the first to identify a novel PKD-specific substrate, DLP1 in mitochondria, as well as the functional role of PKD in cardiac mitochondria. Elucidation of these molecular mechanisms by which PKD-dependent enhanced fission mediates cardiac mitochondrial injury will provide novel insight into the relationship among mitochondrial form, function and Gq PCR signalling.

19.
Leuk Lymphoma ; 59(9): 2068-2074, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29164994

RESUMO

Leukemia is characterized by selective overgrowth of malignant hematopoietic stem cells (HSC's) that interfere with HSC differentiation. Cytoreductive chemotherapy can kill rapidly dividing cancerous cells but cannot eradicate the malignant HSC pool leading to relapses. Leukemic stem cells have several dysregulated pathways and the Janus kinases (JAKs) and signal transducer and activator of transcription (STAT) pathway are prominent among them. STAT3 is an important transcription factor that regulates cell growth, proliferation, and inhibits apoptosis. High STAT3 expression in leukemia has been associated with an increased risk for relapse and decreased overall survival. Multiple strategies for interfering with STAT3 activity in leukemic cells include inhibition of STAT3 phosphorylation, interfering with STAT3 interactions, preventing nuclear transfer, inhibiting transcription and causing interference in STAT: DNA binding. A better understanding of key interactions and upstream mediators of STAT3 activity will help facilitate the development of effective cancer therapies and may result in durable remissions.

20.
Am J Respir Cell Mol Biol ; 58(5): 658-667, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29100477

RESUMO

Hyperproliferative endothelial cells (ECs) play an important role in the pathogenesis of pulmonary arterial hypertension (PAH). Anoctamin (Ano)-1, a calcium-activated chloride channel, can regulate cell proliferation and cell cycle in multiple cell types. However, the expression and function of Ano1 in the pulmonary endothelium is unknown. We examined whether Ano1 was expressed in pulmonary ECs and if altering Ano1 activity would affect EC survival. Expression and localization of Ano1 in rat lung microvascular ECs (RLMVECs) was assessed using immunoblot, immunofluorescence, and subcellular fractionation. Cell counts, flow cytometry, and caspase-3 activity were used to assess changes in cell number and apoptosis in response to the small molecule Ano1 activator, Eact. Changes in mitochondrial membrane potential and mitochondrial reactive oxygen species (mtROS) were assessed using 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine, iodide (mitochondrial membrane potential dye) and mitochondrial ROS dye, respectively. Ano1 is expressed in RLMVECs and is enriched in the mitochondria. Activation of Ano1 with Eact reduced RLMVEC counts through increased apoptosis. Ano1 knockdown blocked the effects of Eact. Ano1 activation increased mtROS, reduced mitochondrial membrane potential, increased p38 phosphorylation, and induced release of apoptosis-inducing factor. mtROS inhibition attenuated Eact-mediated p38 phosphorylation. Pulmonary artery ECs isolated from patients with idiopathic PAH (IPAH) had higher expression of Ano1 and increased cell counts compared with control subjects. Eact treatment reduced cell counts in IPAH cells, which was associated with increased apoptosis. In summary, Ano1 is expressed in lung EC mitochondria. Activation of Ano1 promotes apoptosis of pulmonary ECs and human IPAH-pulmonary artery ECs, likely via increased mtROS and p38 phosphorylation, leading to apoptosis.

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