Publications by authors named "Dong-Qing Hu"

17 Publications

  • Page 1 of 1

Transcriptomic and Functional Analyses of Mitochondrial Dysfunction in Pressure Overload-Induced Right Ventricular Failure.

J Am Heart Assoc 2021 Feb 30;10(4):e017835. Epub 2021 Jan 30.

Department of Pediatrics (Cardiology) Stanford University Palo Alto CA.

Background In complex congenital heart disease patients such as those with tetralogy of Fallot, the right ventricle (RV) is subject to pressure overload, leading to RV hypertrophy and eventually RV failure. The mechanisms that promote the transition from stable RV hypertrophy to RV failure are unknown. We evaluated the role of mitochondrial bioenergetics in the development of RV failure. Methods and Results We created a murine model of RV pressure overload by pulmonary artery banding and compared with sham-operated controls. Gene expression by RNA-sequencing, oxidative stress, mitochondrial respiration, dynamics, and structure were assessed in pressure overload-induced RV failure. RV failure was characterized by decreased expression of electron transport chain genes and mitochondrial antioxidant genes (aldehyde dehydrogenase 2 and superoxide dismutase 2) and increased expression of oxidant stress markers (heme oxygenase, 4-hydroxynonenal). The activities of all electron transport chain complexes decreased with RV hypertrophy and further with RV failure (oxidative phosphorylation: sham 552.3±43.07 versus RV hypertrophy 334.3±30.65 versus RV failure 165.4±36.72 pmol/(s×mL), <0.0001). Mitochondrial fission protein DRP1 (dynamin 1-like) trended toward an increase, while MFF (mitochondrial fission factor) decreased and fusion protein OPA1 (mitochondrial dynamin like GTPase) decreased. In contrast, transcription of electron transport chain genes increased in the left ventricle of RV failure. Conclusions Pressure overload-induced RV failure is characterized by decreased transcription and activity of electron transport chain complexes and increased oxidative stress which are associated with decreased energy generation. An improved understanding of the complex processes of energy generation could aid in developing novel therapies to mitigate mitochondrial dysfunction and delay the onset of RV failure.
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http://dx.doi.org/10.1161/JAHA.120.017835DOI Listing
February 2021

Circulating whole genome miRNA expression corresponds to progressive right ventricle enlargement and systolic dysfunction in adults with tetralogy of Fallot.

PLoS One 2020 11;15(11):e0241476. Epub 2020 Nov 11.

Division of Cardiology, Department of Pediatrics, Stanford University, Stanford, California, United States of America.

Introduction: The adult congenital heart disease population with repaired tetralogy of Fallot (TOF) is subject to chronic volume and pressure loading leading to a 40% probability of right ventricular (RV) failure by the 3rd decade of life. We sought to identify a non-invasive signature of adverse RV remodeling using peripheral blood microRNA (miRNA) profiling to better understand the mechanisms of RV failure.

Methods: Demographic, clinical data, and blood samples were collected from adults with repaired TOF (N = 20). RNA was isolated from the buffy coat of peripheral blood and whole genome miRNA expression was profiled using Agilent's global miRNA microarray platform. Fold change, pathway analysis, and unbiased hierarchical clustering of miRNA expression was performed and correlated to RV size and function assessed by echocardiography performed at or near the time of blood collection.

Results: MiRNA expression was profiled in the following groups: 1. normal RV size (N = 4), 2. mild/moderate RV enlargement (N = 11) and 3. severe RV enlargement (N = 5). 267 miRNAs were downregulated, and 66 were upregulated across the three groups (fold change >2.0, FDR corrected p<0.05) as RV enlargement increased and systolic function decreased. qPCR validation of a subset of these miRNAs identified increasing expression of miRNA 28-3p, 433-3p, and 371b-3p to be associated with increasing RV size and decreasing RV systolic function. Unbiased hierarchical clustering of all patients based on miRNA expression demonstrates three distinct patient clusters that largely coincide with progressive RV enlargement. Pathway analysis of dysregulated miRNAs demonstrates up and downregulation of cell cycle pathways, extracellular matrix proteins and fatty acid synthesis. HIF 1α signaling was downregulated while p53 signaling was predicted to be upregulated.

Conclusion: Adults with TOF have a distinct miRNA profile with progressive RV enlargement and dysfunction implicating cell cycle dysregulation and upregulation in extracellular matrix and fatty acid metabolism. These data suggest peripheral blood miRNA can provide insight into the mechanisms of RV failure and can potentially be used for monitoring disease progression and to develop RV specific therapeutics to prevent RV failure in TOF.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0241476PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7657553PMC
December 2020

Noncanonical WNT Activation in Human Right Ventricular Heart Failure.

Front Cardiovasc Med 2020 7;7:582407. Epub 2020 Oct 7.

Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States.

No medical therapies exist to treat right ventricular (RV) remodeling and RV failure (RVF), in large part because molecular pathways that are specifically activated in pathologic human RV remodeling remain poorly defined. Murine models have suggested involvement of Wnt signaling, but this has not been well-defined in human RVF. Using a candidate gene approach, we sought to identify genes specifically expressed in human pathologic RV remodeling by assessing the expression of 28 WNT-related genes in the RVs of three groups: explanted nonfailing donors (NF, = 29), explanted dilated and ischemic cardiomyopathy, obtained at the time of cardiac transplantation, either with preserved RV function (pRV, = 78) or with RVF ( = 35). We identified the noncanonical WNT receptor ROR2 as transcriptionally strongly upregulated in RVF compared to pRV and NF (Benjamini-Hochberg adjusted < 0.05). ROR2 protein expression correlated linearly to mRNA expression ( = 0.41, = 8.1 × 10) among all RVs, and to higher right atrial to pulmonary capillary wedge ratio in RVF ( = 0.40 = 3.0 × 10). Utilizing Masson's trichrome and ROR2 immunohistochemistry, we identified preferential ROR2 protein expression in fibrotic regions by both cardiomyocytes and noncardiomyocytes. We compared RVF with high and low ROR2 expression, and found that high ROR2 expression was associated with increased expression of the WNT5A/ROR2/Ca responsive protease calpain-μ, cleavage of its target FLNA, and FLNA phosphorylation, another marker of activation downstream of ROR2. ROR2 protein expression as a continuous variable, correlated strongly to expression of calpain-μ ( = 0.25), total FLNA ( = 0.67), calpain cleaved FLNA ( = 0.32) and FLNA phosphorylation ( = 0.62, < 0.05 for all). We demonstrate robust reactivation of a fetal WNT gene program, specifically its noncanonical arm, in human RVF characterized by activation of ROR2/calpain mediated cytoskeleton protein cleavage.
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http://dx.doi.org/10.3389/fcvm.2020.582407DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7575695PMC
October 2020

4HNE Impairs Myocardial Bioenergetics in Congenital Heart Disease-Induced Right Ventricular Failure.

Circulation 2020 Oct 18;142(17):1667-1683. Epub 2020 Aug 18.

Department of Pediatrics (Cardiology) (HT.V.H., N.S., S.L.P., S. Ranjbarvairi, D-Q.H., M.Z., G.F., D.B., S. Reddy), Stanford University, Palo Alto, CA.

Background: In patients with complex congenital heart disease, such as those with tetralogy of Fallot, the right ventricle (RV) is subject to pressure overload stress, leading to RV hypertrophy and eventually RV failure. The role of lipid peroxidation, a potent form of oxidative stress, in mediating RV hypertrophy and failure in congenital heart disease is unknown.

Methods: Lipid peroxidation and mitochondrial function and structure were assessed in right ventricle (RV) myocardium collected from patients with RV hypertrophy with normal RV systolic function (RV fractional area change, 47.3±3.8%) and in patients with RV failure showing decreased RV systolic function (RV fractional area change, 26.6±3.1%). The mechanism of the effect of lipid peroxidation, mediated by 4-hydroxynonenal ([4HNE] a byproduct of lipid peroxidation) on mitochondrial function and structure was assessed in HL1 murine cardiomyocytes and human induced pluripotent stem cell-derived cardiomyocytes.

Results: RV failure was characterized by an increase in 4HNE adduction of metabolic and mitochondrial proteins (16 of 27 identified proteins), in particular electron transport chain proteins. Sarcomeric (myosin) and cytoskeletal proteins (desmin, tubulin) also underwent 4HNE adduction. RV failure showed lower oxidative phosphorylation (moderate RV hypertrophy, 287.6±19.75 versus RV failure, 137.8±11.57 pmol/[sec×mL]; =0.0004), and mitochondrial structural damage. Using a cell model, we show that 4HNE decreases cell number and oxidative phosphorylation (control, 388.1±23.54 versus 4HNE, 143.7±11.64 pmol/[sec×mL]; <0.0001). Carvedilol, a known antioxidant did not decrease 4HNE adduction of metabolic and mitochondrial proteins and did not improve oxidative phosphorylation.

Conclusions: Metabolic, mitochondrial, sarcomeric, and cytoskeletal proteins are susceptible to 4HNE-adduction in patients with RV failure. 4HNE decreases mitochondrial oxygen consumption by inhibiting electron transport chain complexes. Carvedilol did not improve the 4HNE-mediated decrease in oxygen consumption. Strategies to decrease lipid peroxidation could improve mitochondrial energy generation and cardiomyocyte survival and improve RV failure in patients with congenital heart disease.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.120.045470DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7606813PMC
October 2020

Differential Impacts on Bacterial Composition and Abundance in Rhizosphere Compartments between Al-Tolerant and Al-Sensitive Soybean Genotypes in Acidic Soil.

J Microbiol Biotechnol 2020 Aug;30(8):1169-1179

Institute for Plant Molecular Biology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, P.R. China.

In this study, two soybean genotypes . aluminum-tolerant Baxi 10 (BX10) and aluminum-sensitive Bendi 2 (BD2) were used as plant materials and the acidic red soil was used as growth medium. The soil layers from the inside to the outside of the root are: rhizospheric soil after washing (WRH), rhizospheric soil after brushing (BRH) and rhizospheric soil at two sides (SRH), respectively. The rhizosphere bacterial communities were analyzed by high-throughput sequencing of V4 hypervariable regions of 16S rRNA gene (16S rDNA) amplicons via Illumina MiSeq. The results of alpha diversity showed that the BRH and SRH of BX10 were significantly lower on community richness than that of BD2, while the WRH existed no significant difference between BX10 and BD2. Among the three sampling compartments of the same soybean genotype, WRH had the lowest community richness and diversity while existed the highest coverage. Beta diversity analysis results displayed no significant difference for any compartment between the two genotypes, or among the three different sampling compartments for any same soybean genotype. However, the relative abundance of major bacterial taxa specifically nitrogen-fixating and/or aluminum-tolerant bacteria was significantly different in the compartments of the BRH and/or SRH at phylum and genus levels depicting genotype dependent variations in rhizosphere bacterial community. Strikingly, as compared with BRH and SRH, the WRH within the same genotype (BX10 or BD2) always had an enrichment effect on rhizosphere bacteria associated with nitrogen-fixation.
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http://dx.doi.org/10.4014/jmb.2003.03018DOI Listing
August 2020

Novel mechanisms for organic acid-mediated aluminium tolerance in roots and leaves of two contrasting soybean genotypes.

AoB Plants 2017 Nov 17;9(6):plx064. Epub 2017 Nov 17.

Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China.

Aluminium (Al) toxicity is one of the most important limiting factors for crop yield in acidic soils. However, the mechanisms that confer Al tolerance still remain largely unknown. To understand the molecular mechanism that confers different tolerance to Al, we performed global transcriptome analysis to the roots and leaves of two contrasting soybean genotypes, BX10 (Al-tolerant) and BD2 (Al-sensitive) under 0 and 50 μM Al treatments, respectively. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed that the expression levels of the genes involved in lipid/carbohydrate metabolism and jasmonic acid (JA)-mediated signalling pathway were highly induced in the roots and leaves of both soybean genotypes. The gene encoding enzymes, including pyruvate kinase, phosphoenolpyruvate carboxylase, ATP-citrate lyase and glutamate-oxaloacetate transaminase 2, associated with organic acid metabolism were differentially expressed in the BX10 roots. In addition, the genes involved in citrate transport were differentially expressed. Among these genes, was down-regulated only in BD2, whereas the other two multidrug and toxic compound extrusion genes were up-regulated in both soybean genotypes. These findings confirmed that BX10 roots secreted more citrate than BD2 to withstand Al stress. The gene encoding enzymes or regulators, such as lipoxygenase, 12-oxophytodienoate reductase, acyl-CoA oxidase and jasmonate ZIM-domain proteins, involved in JA biosynthesis and signalling were preferentially induced in BD2 leaves. This finding suggests that the JA defence response was activated, possibly weakening the growth of aerial parts because of excessive resource consumption and ATP biosynthesis deficiency. Our results suggest that the Al sensitivity in some soybean varieties could be attributed to the low level of citrate metabolism and exudation in the roots and the high level of JA-mediated defence response in the leaves.
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http://dx.doi.org/10.1093/aobpla/plx064DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5739043PMC
November 2017

Physiological Mitochondrial Fragmentation Is a Normal Cardiac Adaptation to Increased Energy Demand.

Circ Res 2018 01 12;122(2):282-295. Epub 2017 Dec 12.

From the Department of Pediatrics (Cardiology) (M.C., G.F., K.N., M.Z., K.K., G.J., D.-Q.H., S.R., E.S., D.B.) and Cardiovascular Research Institute (M.C., G.F., M.Z., K.K., G.J., D.-Q.H., S.R., E.S., D.B.), Stanford University, CA; and Molecular Cardiology Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA (A.S., R.A.G.).

Rationale: Mitochondria play a dual role in the heart, responsible for meeting energetic demands and regulating cell death. Paradigms have held that mitochondrial fission and fragmentation are the result of pathological stresses, such as ischemia, are an indicator of poor mitochondrial health, and lead to mitophagy and cell death. However, recent studies demonstrate that inhibiting fission also results in decreased mitochondrial function and cardiac impairment, suggesting that fission is important for maintaining cardiac and mitochondrial bioenergetic homeostasis.

Objective: The purpose of this study is to determine whether mitochondrial fission and fragmentation can be an adaptive mechanism used by the heart to augment mitochondrial and cardiac function during a normal physiological stress, such as exercise.

Methods And Results: We demonstrate a novel role for cardiac mitochondrial fission as a normal adaptation to increased energetic demand. During submaximal exercise, physiological mitochondrial fragmentation results in enhanced, rather than impaired, mitochondrial function and is mediated, in part, by β1-adrenergic receptor signaling. Similar to pathological fragmentation, physiological fragmentation is induced by activation of dynamin-related protein 1; however, unlike pathological fragmentation, membrane potential is maintained and regulators of mitophagy are downregulated. Inhibition of fission with P110, Mdivi-1 (mitochondrial division inhibitor), or in mice with cardiac-specific dynamin-related protein 1 ablation significantly decreases exercise capacity.

Conclusions: These findings demonstrate the requirement for physiological mitochondrial fragmentation to meet the energetic demands of exercise, as well as providing additional support for the evolving conceptual framework, where mitochondrial fission and fragmentation play a role in the balance between mitochondrial maintenance of normal physiology and response to disease.
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http://dx.doi.org/10.1161/CIRCRESAHA.117.310725DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5775047PMC
January 2018

miR-21 is associated with fibrosis and right ventricular failure.

JCI Insight 2017 May 4;2(9). Epub 2017 May 4.

Department of Pediatrics, Division of Cardiology, Stanford University, Stanford, California, USA.

Combined pulmonary insufficiency (PI) and stenosis (PS) is a common long-term sequela after repair of many forms of congenital heart disease, causing progressive right ventricular (RV) dilation and failure. Little is known of the mechanisms underlying this combination of preload and afterload stressors. We developed a murine model of PI and PS (PI+PS) to identify clinically relevant pathways and biomarkers of disease progression. Diastolic dysfunction was induced (restrictive RV filling, elevated RV end-diastolic pressures) at 1 month after generation of PI+PS and progressed to systolic dysfunction (decreased RV shortening) by 3 months. RV fibrosis progressed from 1 month (4.4% ± 0.4%) to 3 months (9.2% ± 1%), along with TGF-β signaling and tissue expression of profibrotic miR-21. Although plasma miR-21 was upregulated with diastolic dysfunction, it was downregulated with the onset of systolic dysfunction), correlating with RV fibrosis. Plasma miR-21 in children with PI+PS followed a similar pattern. A model of combined RV volume and pressure overload recapitulates the evolution of RV failure unique to patients with prior RV outflow tract surgery. This progression was characterized by enhanced TGF-β and miR-21 signaling. miR-21 may serve as a plasma biomarker of RV failure, with decreased expression heralding the need for valve replacement.
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http://dx.doi.org/10.1172/jci.insight.91625DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5414555PMC
May 2017

Time-dependent evolution of functional vs. remodeling signaling in induced pluripotent stem cell-derived cardiomyocytes and induced maturation with biomechanical stimulation.

FASEB J 2016 Apr 16;30(4):1464-79. Epub 2015 Dec 16.

*Division of Cardiology, Department of Pediatrics, Stanford Cardiovascular Institute, Division of Cardiovascular Medicine, Department of Medicine, and Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, California, USA; Department of Mechanical Engineering, Stanford University School of Engineering, Stanford, California, USA; and Departments of Pharmacology and Medicine, University of California, San Diego, San Diego, California, USA

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are a powerful platform for uncovering disease mechanisms and assessing drugs for efficacy/toxicity. However, the accuracy with which hiPSC-CMs recapitulate the contractile and remodeling signaling of adult cardiomyocytes is not fully known. We used β-adrenergic receptor (β-AR) signaling as a prototype to determine the evolution of signaling component expression and function during hiPSC-CM maturation. In "early" hiPSC-CMs (less than or equal to d 30), β2-ARs are a primary source of cAMP/PKA signaling. With longer culture, β1-AR signaling increases: from 0% of cAMP generation at d 30 to 56.8 ± 6.6% by d 60. PKA signaling shows a similar increase: 15.7 ± 5.2% (d 30), 49.8 ± 0.5% (d 60), and 71.0 ± 6.1% (d 90). cAMP generation increases 9-fold from d 30 to 60, with enhanced coupling to remodeling pathways (e.g., Akt and Ca(2+)/calmodulin-dependent protein kinase type II) and development of caveolin-mediated signaling compartmentalization. By contrast, cardiotoxicity induced by chronic β-AR stimulation, a major component of heart failure, develops much later: 5% cell death at d 30vs 55% at d 90. Moreover, β-AR maturation can be accelerated by biomechanical stimulation. The differential maturation of β-AR functionalvs remodeling signaling in hiPSC-CMs has important implications for their use in disease modeling and drug testing. We propose that assessment of signaling be added to the indices of phenotypic maturation of hiPSC-CMs.-Jung, G., Fajardo, G., Ribeiro, A. J. S., Kooiker, K. B., Coronado, M., Zhao, M., Hu, D.-Q., Reddy, S., Kodo, K., Sriram, K., Insel, P. A., Wu, J. C., Pruitt, B. L., Bernstein, D. Time-dependent evolution of functionalvs remodeling signaling in induced pluripotent stem cell-derived cardiomyocytes and induced maturation with biomechanical stimulation.
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http://dx.doi.org/10.1096/fj.15-280982DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4799510PMC
April 2016

Selective inhibition of spleen tyrosine kinase (SYK) with a novel orally bioavailable small molecule inhibitor, RO9021, impinges on various innate and adaptive immune responses: implications for SYK inhibitors in autoimmune disease therapy.

Arthritis Res Ther 2013 Oct 4;15(5):R146. Epub 2013 Oct 4.

Introduction: Spleen tyrosine kinase (SYK) is a key integrator of intracellular signals triggered by activated immunoreceptors, including Bcell receptors (BCR) and Fc receptors, which are important for the development and function of lymphoid cells. Given the clinical efficacy of Bcell depletion in the treatment of rheumatoid arthritis and multiple sclerosis, pharmacological modulation of Bcells using orally active small molecules that selectively target SYK presents an attractive alternative therapeutic strategy.

Methods: A SYK inhibitor was developed and assayed in various in vitro systems and in the mouse model of collagen-induced arthritis (mCIA).

Results: A novel ATP-competitive inhibitor of SYK, 6-[(1R,2S)-2-Amino-cyclohexylamino]-4-(5,6-dimethyl-pyridin-2-ylamino)-pyridazine-3-carboxylic acid amide, designated RO9021, with an adequate kinase selectivity profile and oral bioavailability, was developed. In addition to suppression of BCR signaling in human peripheral blood mononuclear cells (PBMC) and whole blood, FcγR signaling in human monocytes, and FcϵR signaling in human mast cells, RO9021 blocked osteoclastogenesis from mouse bone marrow macrophages in vitro. Interestingly, Toll-like Receptor (TLR) 9 signaling in human Bcells was inhibited by RO9021, resulting in decreased levels of plasmablasts, immunoglobulin (Ig) M and IgG upon B-cell differentiation. RO9021 also potently inhibited type I interferon production by human plasmacytoid dendritic cells (pDC) upon TLR9 activation. This effect is specific to TLR9 as RO9021 did not inhibit TLR4- or JAK-STAT-mediated signaling. Finally, oral administration of RO9021 inhibited arthritis progression in the mCIA model, with observable pharmacokinetics (PK)-pharmacodynamic (PD) correlation.

Conclusions: Inhibition of SYK kinase activity impinges on various innate and adaptive immune responses. RO9021 could serve as a starting point for the development of selective SYK inhibitors for the treatment of inflammation-related and autoimmune-related disorders.
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http://dx.doi.org/10.1186/ar4329DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3978604PMC
October 2013

Deletion of the β2-adrenergic receptor prevents the development of cardiomyopathy in mice.

J Mol Cell Cardiol 2013 Oct 3;63:155-64. Epub 2013 Aug 3.

Department of Pediatrics, Stanford University, Stanford, CA, USA.

Beta adrenergic receptor (β-AR) subtypes act through diverse signaling cascades to modulate cardiac function and remodeling. Previous in vitro studies suggest that β1-AR signaling is cardiotoxic whereas β2-AR signaling is cardioprotective, and may be the case during ischemia/reperfusion in vivo. The objective of this study was to assess whether β2-ARs also play a cardioprotective role in the pathogenesis of non-ischemic forms of cardiomyopathy. To dissect the role of β1 vs β2-ARs in modulating MLP (Muscle LIM Protein) cardiomyopathy, we crossbred MLP-/- with β1-/- or β2-/- mice. Deletion of the β2-AR improved survival, cardiac function, exercise capacity and myocyte shortening; by contrast haploinsufficency of the β1-AR reduced survival. Pathologic changes in Ca(2+) handling were reversed in the absence of β2-ARs: peak Ca(2+) and SR Ca(2+) were decreased in MLP-/- and β1+/-/MLP-/- but restored in β2-/-MLP-/-. These changes were associated with reversal of alterations in troponin I and phospholamban phosphorylation. Gi inhibition increased peak and baseline Ca(2+), recapitulating changes observed in the β2-/-/MLP-/-. The L-type Ca(2+) blocker verapamil significantly decreased cardiac function in β2-/-MLP-/- vs WT. We next tested if the protective effects of β2-AR ablation were unique to the MLP model using TAC-induced heart failure. Similar to MLP, β2-/- mice demonstrated delayed progression of heart failure with restoration of myocyte shortening and peak Ca(2+) and Ca(2+) release. Deletion of β2-ARs prevents the development of MLP-/- cardiomyopathy via positive modulation of Ca(2+) due to removal of inhibitory Gi signaling and increased phosphorylation of troponin I and phospholamban. Similar effects were seen after TAC. Unlike previous models where β2-ARs were found to be cardioprotective, in these two models, β2-AR signaling appears to be deleterious, potentially through negative regulation of Ca(2+) dynamics.
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http://dx.doi.org/10.1016/j.yjmcc.2013.07.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3791213PMC
October 2013

Physiologic and molecular characterization of a murine model of right ventricular volume overload.

Am J Physiol Heart Circ Physiol 2013 May 15;304(10):H1314-27. Epub 2013 Mar 15.

Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305, USA.

Pulmonary insufficiency (PI) is a common long-term sequel after repair of tetralogy of Fallot, causing progressive right ventricular (RV) dilation and failure. We describe the physiologic and molecular characteristics of the first murine model of RV volume overload. PI was created by entrapping the pulmonary valve leaflets with sutures. Imaging, catheterization, and exercise testing were performed at 1, 3, and 6 mo and compared with sham controls. RNA from the RV free wall was hybridized to Agilent whole genome oligonucleotide microarrays. Volume overload resulted in RV enlargement, decreased RV outflow tract shortening fraction at 1 mo followed by normalization at 3 and 6 mo (39 ± 2, 44 ± 2, and 41 ± 2 vs. 46 ± 3% in sham), early reversal of early and late diastolic filling velocities (E/A ratio) followed by pseudonormalization (0.87 ± 0.08, 0.82 ± 0.08, and 0.96 ± 0.08 vs. 1.04 ± 0.03; P < 0.05), elevated end-diastolic pressure (7.6 ± 0.7, 6.9 ± 0.8, and 7 ± 0.5 vs. 2.7 ± 0.2 mmHg; P < 0.05), and decreased exercise duration (26 ± 0.4, 26 ± 1, and 22 ± 1.3 vs. 30 ± 1.1 min; P < 0.05). Subendocardial RV fibrosis was evident by 1 mo. At 1 mo, 372 genes were significantly downregulated. Mitochondrial pathways and G protein-coupled receptor signaling were the most represented categories. At 3 mo, 434 genes were upregulated and 307 downregulated. While many of the same pathways continued to be downregulated, TNF-α, transforming growth factor-β(1) (TGF-β(1)), p53-signaling, and extracellular matrix (ECM) remodeling transitioned from down- to upregulated. We describe a novel murine model of chronic RV volume overload recapitulating aspects of the clinical disease with gene expression changes suggesting early mitochondrial bioenergetic dysfunction, enhanced TGF-β signaling, ECM remodeling, and apoptosis.
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http://dx.doi.org/10.1152/ajpheart.00776.2012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3652064PMC
May 2013

3-Amido pyrrolopyrazine JAK kinase inhibitors: development of a JAK3 vs JAK1 selective inhibitor and evaluation in cellular and in vivo models.

J Med Chem 2013 Jan 19;56(1):345-56. Epub 2012 Dec 19.

Hoffmann-La Roche, 340 Kingsland Street, Nutley, New Jersey 07110, USA.

The Janus kinases (JAKs) are involved in multiple signaling networks relevant to inflammatory diseases, and inhibition of one or more members of this class may modulate disease activity or progression. We optimized a new inhibitor scaffold, 3-amido-5-cyclopropylpyrrolopyrazines, to a potent example with reasonable kinome selectivity, including selectivity for JAK3 versus JAK1, and good biopharmaceutical properties. Evaluation of this analogue in cellular and in vivo models confirmed functional selectivity for modulation of a JAK3/JAK1-dependent IL-2 stimulated pathway over a JAK1/JAK2/Tyk2-dependent IL-6 stimulated pathway.
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http://dx.doi.org/10.1021/jm301646kDOI Listing
January 2013

Dynamic microRNA expression during the transition from right ventricular hypertrophy to failure.

Physiol Genomics 2012 May 27;44(10):562-75. Epub 2012 Mar 27.

Department of Pediatrics, Stanford University School of Medicine, Stanford, California 94305, USA.

MicroRNAs (miRs) are small, noncoding RNAs that are emerging as crucial regulators of cardiac remodeling in left ventricular hypertrophy (LVH) and failure (LVF). However, there are no data on their role in right ventricular hypertrophy (RVH) and failure (RVF). This is a critical question given that the RV is uniquely at risk in patients with congenital right-sided obstructive lesions and in those with systemic RVs. We have developed a murine model of RVH and RVF using pulmonary artery constriction (PAC). miR microarray analysis of RV from PAC vs. control demonstrates altered miR expression with gene targets associated with cardiomyocyte survival and growth during hypertrophy (miR 199a-3p) and reactivation of the fetal gene program during heart failure (miR-208b). The transition from hypertrophy to heart failure is characterized by apoptosis and fibrosis (miRs-34, 21, 1). Most are similar to LVH/LVF. However, there are several key differences between RV and LV: four miRs (34a, 28, 148a, and 93) were upregulated in RVH/RVF that are downregulated or unchanged in LVH/LVF. Furthermore, there is a corresponding downregulation of their putative target genes involving cell survival, proliferation, metabolism, extracellular matrix turnover, and impaired proteosomal function. The current study demonstrates, for the first time, alterations in miRs during the process of RV remodeling and the gene regulatory pathways leading to RVH and RVF. Many of these alterations are similar to those in the afterload-stressed LV. miRs differentially regulated between the RV and LV may contribute to the RVs increased susceptibility to heart failure.
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http://dx.doi.org/10.1152/physiolgenomics.00163.2011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3426410PMC
May 2012

RN486, a selective Bruton's tyrosine kinase inhibitor, abrogates immune hypersensitivity responses and arthritis in rodents.

J Pharmacol Exp Ther 2012 Apr 6;341(1):90-103. Epub 2012 Jan 6.

Department of Inflammation Discovery, Hoffmann-la-Roche, 340 Kingsland Street, Nutley, NJ 07110, USA.

Genetic mutation and pharmacological inhibition of Bruton's tyrosine kinase (Btk) both have been shown to prevent the development of collagen-induced arthritis (CIA) in mice, providing a rationale for the development of Btk inhibitors for treating rheumatoid arthritis (RA). In the present study, we characterized a novel Btk inhibitor, 6-cyclopropyl-8-fluoro-2-(2-hydroxymethyl-3-{1-methyl-5-[5-(4-methyl-piperazin-1-yl)-pyridin-2-ylamino]-6-oxo-1,6-dihydro-pyridin-3-yl}-phenyl)-2H-isoquinolin-1-one (RN486), in vitro and in rodent models of immune hypersensitivity and arthritis. We demonstrated that RN486 not only potently and selectively inhibited the Btk enzyme, but also displayed functional activities in human cell-based assays in multiple cell types, blocking Fcε receptor cross-linking-induced degranulation in mast cells (IC(50) = 2.9 nM), Fcγ receptor engagement-mediated tumor necrosis factor α production in monocytes (IC(50) = 7.0 nM), and B cell antigen receptor-induced expression of an activation marker, CD69, in B cells in whole blood (IC(50) = 21.0 nM). RN486 displayed similar functional activities in rodent models, effectively preventing type I and type III hypersensitivity responses. More importantly, RN486 produced robust anti-inflammatory and bone-protective effects in mouse CIA and rat adjuvant-induced arthritis (AIA) models. In the AIA model, RN486 inhibited both joint and systemic inflammation either alone or in combination with methotrexate, reducing both paw swelling and inflammatory markers in the blood. Together, our findings not only demonstrate that Btk plays an essential and conserved role in regulating immunoreceptor-mediated immune responses in both humans and rodents, but also provide evidence and mechanistic insights to support the development of selective Btk inhibitors as small-molecule disease-modifying drugs for RA and potentially other autoimmune diseases.
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http://dx.doi.org/10.1124/jpet.111.187740DOI Listing
April 2012

Selective pharmacological blockade of the TRPV1 receptor suppresses sensory reflexes of the rodent bladder.

J Urol 2009 Aug 18;182(2):776-85. Epub 2009 Jun 18.

Roche Palo Alto, Palo Alto, California 94304, USA.

Purpose: We investigated the pharmacological effect of TRPV1 antagonists in anesthetized rodent models of bladder function.

Materials And Methods: The TRPV1 antagonists JNJ17203212 and JYL1421 were evaluated in the anesthetized rat volume induced micturition reflex model. JNJ17203212 was further evaluated in this model in capsaicin (Sigma) desensitized rats, and in rat capsaicin and mouse citric acid models of irritant induced detrusor overactivity.

Results: Systemic JNJ17203212 and JYL1421 administration in the anesthetized rat volume induced micturition reflex model resulted in an increased micturition threshold volume. JNJ17203212 also decreased bladder contraction amplitude but JYL1421 had no effect. Capsaicin desensitization significantly increased baseline micturition threshold volume and decreased bladder contraction amplitude in the volume induced micturition reflex model compared to those in sham treated controls and JNJ17203212 produced no further effect after capsaicin desensitization. JNJ17203212 was also effective in 2 models of irritant induced detrusor overactivity, preventing the decrease in micturition threshold volume and the increase in bladder contraction amplitude observed with intravesical instillation of 10 microM capsaicin, and the decreased voiding interval induced by intravesical citric acid.

Conclusions: The TRPV1 antagonists JNJ17203212 and JYL1421 increased the threshold for activation of the micturition reflex in the anesthetized rat volume induced micturition reflex model. This effect appeared to be mediated by capsaicin sensitive afferents. JNJ17203212 also inhibited detrusor overactivity induced by intravesical capsaicin and intravesical citric acid. These data extend our understanding of the role of TRPV1 in sensory modulation of the micturition reflex under nonirritant and inflammatory conditions.
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http://dx.doi.org/10.1016/j.juro.2009.03.085DOI Listing
August 2009

[The prevalence and risk factors for coronary stenosis in patients with cerebral infarction].

Zhonghua Nei Ke Za Zhi 2008 Aug;47(8):658-60

Department and Interventional Therapy, Zhangye People's Hospital in Gansu Province, Zhangye 734000, China.

Objective: To study the morbidity rate of and relevance to coronary stenosis in cerebral infarction patients.

Methods: CT coronary angiography was performed in 112 cases of cerebral infarction after CT cerebral angiography. Multivariate logistic regression analysis was carried out between the clinical data and coronary stenosis.

Results: In 112 cases receiving CT cerebral angiography, the morbidity rate of coronary stenosis was 46.4%. In 95 cerebral infarction patients, the morbidity rate of coronary stenosis was 51.6%. Multivariate logistic analysis showed that age, hypertension, hyperlipidemia, significant narrowing of cerebral artery were identified as independent predictors for coronary stenosis.

Conclusions: Heart examination with 64 row CT should be routinely performed after cerebral angiography in cerebral infarction patients, especially in those with age greater than 65 years, hypertension, hyperlipidemia and significant narrowing of cerebral artery so as to detect coronary stenosis early.
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August 2008