Jeffery D Molkentin

Howard Hughes Medical Institute, Ashburn, Virginia, United States

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Publications (370)3252.57 Total impact

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    ABSTRACT: There are 3 protein phosphatase 1 (PP1) catalytic isoforms (α, β and γ) encoded within the mammalian genome. These 3 gene products share ~90% amino acid homology within their catalytic domains but each has unique N- and C-termini that likely underlie distinctive subcellular localization or functionality. In this study, we assessed the effect associated with loss of each PP1 isoform in the heart using a conditional Cre-loxP targeting approach in mice. Ppp1ca-loxP, Ppp1cb-loxP and Ppp1cc-oxP alleles were crossed with either an Nkx2.5-Cre knock-in containing allele for early embryonic deletion or a tamoxifen inducible α-myosin heavy chain (αMHC)-MerCreMer transgene for adult and cardiac-specific deletion. We determined that while deletion of Ppp1ca (PP1α) or Ppp1cc (PP1γ) had little effect on the whole heart, deletion of Ppp1cb (PP1β) resulted in concentric remodeling of the heart, interstitial fibrosis and contractile dysregulation, using either the embryonic or adult-specific Cre-expressing alleles. However, myocytes isolated from Ppp1cb deleted hearts surprisingly showed enhanced contractility. Mechanistically we found that deletion of any of the 3 PP1 gene-encoding isoforms had no effect on phosphorylation of phospholamban, nor were Ca(2+) handling dynamics altered in adult myocytes from Ppp1cb deleted hearts. However, loss of Ppp1cb from the heart, but not Ppp1ca or Ppp1cc, resulted in elevated phosphorylation of myofilament proteins such as myosin light chain 2 and cardiac myosin binding protein C, consistent with an enriched localization profile of this isoform to the sarcomeres. These results suggest a unique functional role for the PP1β isoform in affecting cardiac contractile function.
    Journal of Molecular and Cellular Cardiology 09/2015; DOI:10.1016/j.yjmcc.2015.08.018 · 4.66 Impact Factor
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    ABSTRACT: Canonical protein phosphatase 3/calcineurin signaling is central to numerous physiological processes. Here we provide evidence that calcineurin plays a pivotal role in controlling systemic energy and body weight homeostasis. Knockdown of calcineurin in Drosophila melanogaster led to a decrease in body weight and energy stores, and increased energy expenditure. In mice, global deficiency of catalytic subunit Ppp3cb, and tissue-specific ablation of regulatory subunit Ppp3r1 from skeletal muscle, but not adipose tissue or liver, led to protection from high-fat-diet-induced obesity and comorbid sequelæ. Ser637 hyperphosphorylation of dynamin-related protein 1 (Drp1) in skeletal muscle of calcineurin-deficient mice was associated with mitochondrial elongation into power-cable-shaped filaments and increased mitochondrial respiration, but also with attenuated exercise performance. Our data suggest that calcineurin acts as highly conserved pivot for the adaptive metabolic responses to environmental changes such as high-fat, high-sugar diets or exercise.
    Cell metabolism 09/2015; DOI:10.1016/j.cmet.2015.08.022 · 17.57 Impact Factor
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    ABSTRACT: Abstract—We have previously shown,that the calcium-calmodulin‐regulated phosphatase calcineurin (PP2B) is sufficient to induce cardiac hypertrophy that transitions to heart failure in transgenic mice. Given the rapid onset of heart failure in these mice, we hypothesized that calcineurin signaling would stimulate myocardial cell apoptosis. However, utilizing multiple approaches, we determined that calcineurin-mediated hypertrophy protected cardiac myocytes from apoptosis, suggesting a model,of heart failure that is independent,of apoptosis. Adenovirally mediated,gene,transfer of a
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    ABSTRACT: Stromal interaction molecule 1 (STIM1) is a Ca(2+) sensor that partners with Orai1 to elicit Ca(2+) entry in response to endoplasmic reticulum (ER) Ca(2+) store depletion. While store-operated Ca(2+) entry (SOCE) is important for maintaining ER Ca(2+) homeostasis in non-excitable cells, it is unclear what role it plays in the heart, although STIM1 is expressed in the heart and upregulated during disease. Here we analyzed transgenic mice with STIM1 overexpression in the heart to model the known increase of this protein in response to disease. As expected, STIM1 transgenic myocytes showed enhanced Ca(2+) entry following store depletion and partial co-localization with the type 2 ryanodine receptor (RyR2) within the sarcoplasmic reticulum (SR), as well as enrichment around the sarcolemma. STIM1 transgenic mice exhibited sudden cardiac death as early as 6weeks of age, while mice surviving past 12weeks of age developed heart failure with hypertrophy, induction of the fetal gene program, histopathology and mitochondrial structural alterations, loss of ventricular functional performance and pulmonary edema. Younger, pre-symptomatic STIM1 transgenic mice exhibited enhanced pathology following pressure overload stimulation or neurohumoral agonist infusion, compared to controls. Mechanistically, cardiac myocytes isolated from STIM1 transgenic mice displayed spontaneous Ca(2+) transients that were prevented by the SOCE blocker SKF-96365, increased L-type Ca(2+) channel (LTCC) current, and enhanced Ca(2+) spark frequency. Moreover, adult cardiac myocytes from STIM1 transgenic mice showed both increased diastolic Ca(2+) and maximal transient amplitude but no increase in total SR Ca(2+) load. Associated with this enhanced Ca(2+) profile was an increase in cardiac nuclear factor of activated T-cells (NFAT) and Ca(2+)/calmodulin-dependent kinase II (CaMKII) activity. We conclude that STIM1 has an unexpected function in the heart where it alters communication between the sarcolemma and SR resulting in greater Ca(2+) flux and a leaky SR compartment. Copyright © 2015. Published by Elsevier Ltd.
    Journal of Molecular and Cellular Cardiology 08/2015; 87. DOI:10.1016/j.yjmcc.2015.07.032 · 4.66 Impact Factor
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    ABSTRACT: In the heart, augmented Ca(2+) fluxing drives contractility and ATP generation through mitochondrial Ca(2+) loading. Pathologic mitochondrial Ca(2+) overload with ischemic injury triggers mitochondrial permeability transition pore (MPTP) opening and cardiomyocyte death. Mitochondrial Ca(2+) uptake is primarily mediated by the mitochondrial Ca(2+) uniporter (MCU). Here, we generated mice with adult and cardiomyocyte-specific deletion of Mcu, which produced mitochondria refractory to acute Ca(2+) uptake, with impaired ATP production, and inhibited MPTP opening upon acute Ca(2+) challenge. Mice lacking Mcu in the adult heart were also protected from acute ischemia-reperfusion injury. However, resting/basal mitochondrial Ca(2+) levels were normal in hearts of Mcu-deleted mice, and mitochondria lacking MCU eventually loaded with Ca(2+) after stress stimulation. Indeed, Mcu-deleted mice were unable to immediately sprint on a treadmill unless warmed up for 30 min. Hence, MCU is a dedicated regulator of short-term mitochondrial Ca(2+) loading underlying a "fight-or-flight" response that acutely matches cardiac workload with ATP production. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
    Cell Reports 06/2015; 12(1). DOI:10.1016/j.celrep.2015.06.002 · 8.36 Impact Factor
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    A R Burr · J D Molkentin
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    ABSTRACT: Muscular dystrophy (MD) refers to a clinically and genetically heterogeneous group of degenerative muscle disorders characterized by progressive muscle wasting and often premature death. Although the primary defect underlying most forms of MD typically results from a loss of sarcolemmal integrity, the secondary molecular mechanisms leading to muscle degeneration and myofiber necrosis is debated. One hypothesis suggests that elevated or dysregulated cytosolic calcium is the common transducing event, resulting in myofiber necrosis in MD. Previous measurements of resting calcium levels in myofibers from dystrophic animal models or humans produced equivocal results. However, recent studies in genetically altered mouse models have largely solidified the calcium hypothesis of MD, such that models with artificially elevated calcium in skeletal muscle manifest fulminant dystrophic-like disease, whereas models with enhanced calcium clearance or inhibited calcium influx are resistant to myofiber death and MD. Here, we will review the field and the recent cadre of data from genetically altered mouse models, which we propose have collectively mostly proven the hypothesis that calcium is the primary effector of myofiber necrosis in MD. This new consensus on calcium should guide future selection of drugs to be evaluated in clinical trials as well as gene therapy-based approaches.Cell Death and Differentiation advance online publication, 19 June 2015; doi:10.1038/cdd.2015.65.
    Cell death and differentiation 06/2015; 22(9). DOI:10.1038/cdd.2015.65 · 8.18 Impact Factor
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    ABSTRACT: Acute pancreatitis is caused by toxins that induce acinar cell calcium overload, zymogen activation, cytokine release and cell death, yet is without specific drug therapy. Mitochondrial dysfunction has been implicated but the mechanism not established. We investigated the mechanism of induction and consequences of the mitochondrial permeability transition pore (MPTP) in the pancreas using cell biological methods including confocal microscopy, patch clamp technology and multiple clinically representative disease models. Effects of genetic and pharmacological inhibition of the MPTP were examined in isolated murine and human pancreatic acinar cells, and in hyperstimulation, bile acid, alcoholic and choline-deficient, ethionine-supplemented acute pancreatitis. MPTP opening was mediated by toxin-induced inositol trisphosphate and ryanodine receptor calcium channel release, and resulted in diminished ATP production, leading to impaired calcium clearance, defective autophagy, zymogen activation, cytokine production, phosphoglycerate mutase 5 activation and necrosis, which was prevented by intracellular ATP supplementation. When MPTP opening was inhibited genetically or pharmacologically, all biochemical, immunological and histopathological responses of acute pancreatitis in all four models were reduced or abolished. This work demonstrates the mechanism and consequences of MPTP opening to be fundamental to multiple forms of acute pancreatitis and validates the MPTP as a drug target for this disease. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to
    Gut 06/2015; DOI:10.1136/gutjnl-2014-308553 · 14.66 Impact Factor
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    ABSTRACT: During apoptosis the pro-death Bcl-2 family members Bax and Bak induce mitochondrial outer membrane permeabilization (MOMP) to mediate cell death. Recently, it was shown that Bax and Bak are also required for mitochondrial permeability transition pore (MPTP)-dependent necrosis, where, in their non-oligomeric state, they enhance permeability characteristics of the outer mitochondrial membrane. Necroptosis is another form of regulated necrosis involving the death receptors and receptor interacting protein kinases (RIP proteins, by Ripk genes). Here, we show cells or mice deficient for Bax/Bak or cyclophilin D, a protein that regulates MPTP opening, are resistant to cell death induced by necroptotic mediators. We show that Bax/Bak oligomerization is required for necroptotic cell death and that this oligomerization reinforces MPTP opening. Mechanistically, we observe mixed lineage kinase domain-like (MLKL) protein and cofilin-1 translocation to the mitochondria following necroptosis induction, while expression of the mitochondrial matrix isoform of the antiapoptotic Bcl-2 family member, myeloid cell leukemia 1 (Mcl-1), is significantly reduced. Some of these effects are lost with necroptosis inhibition in Bax/Bak1 double null, Ppif-/-, or Ripk3-/- fibroblasts. Hence, downstream mechanisms of cell death induced by necroptotic stimuli utilize both Bax/Bak to generate apoptotic pores in the outer mitochondrial membrane as well as MPTP opening in association with known mitochondrial death modifying proteins.
    PLoS ONE 06/2015; 10(6):e0130520. DOI:10.1371/journal.pone.0130520 · 3.23 Impact Factor
  • Jason Karch · Jeffery D Molkentin
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    ABSTRACT: Although the molecular effectors of apoptotic cell death have been largely annotated over the past 30 years, leading to a strong biological understanding of this process and its importance in cell biology, cell death through necrosis has only recently been accepted as a similarly regulated process with definable molecular effectors. The mitochondria are important and central mediators of both apoptosis and regulated necrosis. In apoptosis, the B-cell leukemia/lymphoma 2 (Bcl-2) family members Bcl-2-associated protein x (Bax) and Bcl-2 homologues antagonist/killer (Bak) undergo oligomerization in the outer mitochondrial membrane resulting in the release of apoptosis inducing substrates and the activation of caspases and nucleases. In contrast, during necrosis the mitochondria become dysfunctional and maladaptive in conjunction with reactive oxygen species production and the loss of ATP production, in part through opening of the mitochondrial permeability transition pore. Although regulated necrosis is caspase-independent, recent evidence has shown that it still requires the apoptotic regulators Bax/Bak, which can regulate the permeability characteristics of the outer mitochondrial membrane in their nonoligomerized state. Here, we review the nonapoptotic side of Bcl-2 family, specifically the role of Bax/Bak in regulated necrotic cell death. We will also discuss how these Bcl-2 family member effectors could be part of a larger integrated network that ultimately decides the fate of a given cell somewhere within a molecular continuum between apoptosis and regulated necrosis. © 2015 American Heart Association, Inc.
    Circulation Research 05/2015; 116(11):1800-1809. DOI:10.1161/CIRCRESAHA.116.305421 · 11.02 Impact Factor
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    ABSTRACT: Radiocontrast agents are required for radiographic procedures, but these agents can injure tissues by unknown mechanisms. We investigated whether exposure of pancreatic tissues to radiocontrast agents during endoscopic retrograde cholangiopancreatography (ERCP) causes pancreatic inflammation, and studied the effects of these agents on human cell lines and in mice. We exposed mouse and human acinar cells to the radiocontrast agent iohexol (Omnipaque) and measured intracellular release of Ca(2+), calcineurin activation (using a luciferase reporter), activation of nuclear factor-κB (NF-κB, using a luciferase reporter), and cell necrosis (via propidium iodide uptake). We infused the radiocontrast agent into the pancreatic ducts of wild type mice (C57BL/6) to create a mouse model of post-ERCP pancreatitis; some mice were given intraperitoneal injections of the calcineurin inhibitor FK506 before and after infusion of the radiocontrast agent. CnAβ(-/-) mice were also used. This experiment was also performed in mice given infusions of AAV6-NF-κB-luciferase, to assess activation of this transcription factor in vivo. Incubation of mouse and human acinar cells, but not HEK293 or COS7 cells, with iohexol led to a peak and then plateau in Ca(2+) signaling, along with activation of the transcription factors NF-κB and NFAT. Suppressing Ca(2+) signaling or calcineurin with BAPTA, cyclosporine A, or FK506 prevented activation of NF-κB and acinar cell injury. Calcineurin Aβ-deficient mice were protected against induction of pancreatic inflammation by iohexol. The calcineurin inhibitor FK506 prevented contrast-induced activation of NF-κB in pancreata of mice; this was observed by live imaging of mice given infusions of AAV6- NF-kB-luciferase. Radiocontrast agents cause pancreatic inflammation in mice, via activation of NF-κB, Ca(2+) signaling, and calcineurin. Calcineurin inhibitors might be developed to prevent post-ERCP pancreatitis in patients. Copyright © 2015 AGA Institute. Published by Elsevier Inc. All rights reserved.
    Gastroenterology 05/2015; 149(3). DOI:10.1053/j.gastro.2015.05.004 · 16.72 Impact Factor
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    ABSTRACT: The matricellular secreted protein, connective tissue growth factor (CTGF), is upregulated in response to cardiac injury or with transforming growth factor β (TGFβ) stimulation, where it has been suggested to function as a fibrotic effector. Here we generated transgenic mice with inducible cardiac-specific CTGF overexpression, mice with cardiac-specific expression of an activated TGFβ mutant protein, mice with cardiac-specific deletion of Ctgf, and mice in which Ctgf was also deleted from fibroblasts in the heart. Remarkably, neither gain nor loss of CTGF in the heart affected cardiac pathology and propensity toward early lethality due to TGFβ over activation in the heart. Also, neither heart-specific Ctgf deletion nor CTGF overexpression altered cardiac remodeling and function with aging or after multiple acute stress stimuli. Cardiac fibrosis was also unchanged by modulation of CTGF levels in the heart with aging, pressure overload, agonist infusion or TGFβ overexpression. However, CTGF did mildly alter the overall cardiac response to TGFβ when pressure overload stimulation was applied. CTGF has been proposed to function as a critical TGFβ effector in underlying tissue remodeling and fibrosis throughout the body, although our results suggest that CTGF is of minimal importance and is an unlikely therapeutic vantage point for the heart. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
    Molecular and Cellular Biology 04/2015; 35(12). DOI:10.1128/MCB.00199-15 · 4.78 Impact Factor
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    ABSTRACT: Sarcolipin (SLN) is a regulator of sarco(endo)plasmic reticulum calcium ATPase (SERCA) in skeletal muscle. Recent studies using SLN null mice have identified SLN as a key player in muscle thermogenesis and metabolism. In this study, we exploited a SLN overexpression (Sln(OE)) mouse model to determine whether increased SLN level affected muscle contractile properties, exercise capacity/ fatigue and metabolic rate in whole animals and isolated muscle. We found that Sln(OE) mice are more resistant to fatigue and can run significantly longer distance than wild type (WT). Studies with isolated extensor digitorum longus (EDL) muscle show that Sln(OE) EDL produces higher twitch force than WT. The force-frequency curves were not different between WT and Sln(OE) EDLs, but at lower frequencies the pyruvate induced potentiation of force was significantly higher in Sln(OE) EDL. SLN overexpression did not alter the twitch and force frequency curve in isolated soleus muscle. However, during a 10 minute fatigue protocol both EDL and soleus from Sln(OE) mice fatigued significantly less than WT muscles. Interestingly, Sln(OE) muscles showed higher carnitine palmitoyl transferase-1 protein expression, which could enhance fatty acid metabolism. In addition, lactate dehydrogenase expression was higher in Sln(OE) EDL suggesting increased glycolytic capacity. We also found an increase in store operated calcium entry (SOCE), in isolated flexor digitorum brevis fibers of Sln(OE) than WT mice. These data allow us to conclude that increased SLN expression improves skeletal muscle performance during prolonged muscle activity, by increasing SOCE and muscle energetics. Copyright © 2014, Journal of Applied Physiology.
    Journal of Applied Physiology 02/2015; 118(8):jap.01066.2014. DOI:10.1152/japplphysiol.01066.2014 · 3.06 Impact Factor
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    ABSTRACT: Duchenne muscular dystrophy (DMD) is characterized by progressive muscle wasting secondary to repeated muscle damage and inadequate repair. Elevations in intracellular free Ca2+ have been implicated in disease progression and SERCA1 overexpression has been shown to ameliorate the dystrophic phenotype in mdx mice. The purpose of this study was to assess the effects of SERCA1 overexpression in the more severe mdx/Utr-/- mouse model of DMD. Mice overexpressing SERCA1 were crossed with mdx/Utr+/- mice to generate mdx/Utr-/-/+SERCA1 mice and compared to wild-type (WT), WT/+SERCA1, mdx/+SERCA1 and genotype controls. Mice were assessed at ~12 weeks of age for changes in Ca2+-handling, muscle mass, quadriceps torque, markers of muscle damage and response to repeated eccentric contractions. SERCA1 overexpressing mice had a 2- to 3-fold increase in maximal SR Ca2+ ATPase activity compared to WT which was associated with normalization in body mass for both mdx/+SERCA1 and mdx/Utr-/-/+SERCA1. Torque deficit in the quadriceps after eccentric injury was 2.7-fold greater in mdx/Utr-/- vs. WT mice, but only 1.5-fold greater in mdx/Utr-/-/+SERCA1 vs. WT mice, an attenuation of 44%. Markers of muscle damage (% central nucleated fibres, necrotic area, and serum creatine kinase levels) were higher in both mdx and mdx/Utr-/- vs. WT and all were attenuated by overexpression of SERCA1. These data indicate that SERCA1 overexpression ameliorates functional impairments and cellular markers of damage in a more severe mouse model of DMD. These findings support targeting intracellular Ca2+ control as a therapeutic approach for DMD.
    AJP Cell Physiology 02/2015; 308(9). DOI:10.1152/ajpcell.00341.2014 · 3.78 Impact Factor
  • Jennifer Q Kwong · Jeffery D Molkentin
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    ABSTRACT: Prolonged mitochondrial permeability transition pore (MPTP) opening results in mitochondrial energetic dysfunction, organelle swelling, rupture, and typically a type of necrotic cell death. However, acute opening of the MPTP has a critical physiologic role in regulating mitochondrial Ca(2+) handling and metabolism. Despite the physiological and pathological roles that the MPTP orchestrates, the proteins that comprise the pore itself remain an area of ongoing investigation. Here, we will discuss the molecular composition of the MPTP and its role in regulating cardiac physiology and disease. A better understanding of MPTP structure and function will likely suggest novel cardioprotective therapeutic approaches. Copyright © 2015 Elsevier Inc. All rights reserved.
    Cell Metabolism 02/2015; 21(2):206-214. DOI:10.1016/j.cmet.2014.12.001 · 17.57 Impact Factor
  • Jop H van Berlo · Jeffery D Molkentin
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    ABSTRACT: Cardiac regeneration is a rapidly evolving and controversial field of research. The identification some 12 years ago of progenitor cells that reside within the heart spurred enthusiasm for cell-based regenerative therapies. However, recent evidence has called into question both the presence of a biologically important stem cell population in the heart and the ability of exogenously derived cells to promote regeneration through direct formation of new cardiomyocytes. Here, we discuss recent developments that suggest an emerging consensus on the ability of different cell types to regenerate the adult mammalian heart.
    Nature Medicine 12/2014; 20(12):1386-93. DOI:10.1038/nm.3764 · 27.36 Impact Factor
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    ABSTRACT: Latent transforming growth factor-β (TGFβ) binding proteins (LTBPs) bind to inactive TGFβ in the extracellular matrix. In mice, muscular dystrophy symptoms are intensified by a genetic polymorphism that changes the hinge region of LTBP, leading to increased proteolytic susceptibility and TGFβ release. We have found that the hinge region of human LTBP4 was also readily proteolysed and that proteolysis could be blocked by an antibody to the hinge region. Transgenic mice were generated to carry a bacterial artificial chromosome encoding the human LTBP4 gene. These transgenic mice displayed larger myofibers, increased damage after muscle injury, and enhanced TGFβ signaling. In the mdx mouse model of Duchenne muscular dystrophy, the human LTBP4 transgene exacerbated muscular dystrophy symptoms and resulted in weaker muscles with an increased inflammatory infiltrate and greater LTBP4 cleavage in vivo. Blocking LTBP4 cleavage may be a therapeutic strategy to reduce TGFβ release and activity and decrease inflammation and muscle damage in muscular dystrophy.
    Science translational medicine 10/2014; 6(259):259ra144. DOI:10.1126/scitranslmed.3010018 · 15.84 Impact Factor
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    ABSTRACT: The Ras-related guanosine triphosphatase RhoA mediates pathological cardiac hypertrophy, but also promotes cell survival and is cardioprotective after ischemia/reperfusion injury. To understand how RhoA mediates these opposing roles in the myocardium, we generated mice with a cardiomyocyte-specific deletion of RhoA. Under normal conditions, the hearts from these mice showed functional, structural, and growth parameters similar to control mice. Additionally, the hearts of the cardiomyocyte-specific, RhoA-deficient mice subjected to transverse aortic constriction (TAC)-a procedure that induces pressure overload and, if prolonged, heart failure-exhibited a similar amount of hypertrophy as those of the wild-type mice subjected to TAC. Thus, neither normal cardiac homeostasis nor the initiation of compensatory hypertrophy required RhoA in cardiomyocytes. However, in response to chronic TAC, hearts from mice with cardiomyocyte-specific deletion of RhoA showed greater dilation, with thinner ventricular walls and larger chamber dimensions, and more impaired contractile function than those from control mice subjected to chronic TAC. These effects were associated with aberrant calcium signaling, as well as decreased activity of extracellular signal-regulated kinases 1 and 2 (ERK1/2) and AKT. In addition, hearts from mice with cardiomyocyte-specific RhoA deficiency also showed less fibrosis in response to chronic TAC, with decreased transcriptional activation of genes involved in fibrosis, including myocardin response transcription factor (MRTF) and serum response factor (SRF), suggesting that the fibrotic response to stress in the heart depends on cardiomyocyte-specific RhoA signaling. Our data indicated that RhoA regulates multiple pathways in cardiomyocytes, mediating both cardioprotective (hypertrophy without dilation) and cardio-deleterious effects (fibrosis).
    Science Signaling 10/2014; 7(348):ra100. DOI:10.1126/scisignal.2005262 · 6.28 Impact Factor
  • Lei Li · Yi Chen · Jessica Doan · Jason Murray · Jeffery D Molkentin · Qinghang Liu
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    ABSTRACT: Background: Programmed necrosis (necroptosis) plays an important role in development, tissue homeostasis, and disease pathogenesis. The molecular mechanisms that regulate necroptosis in the heart and its physiological relevance in myocardial remodeling and heart failure remain largely unknown. Methods and results: Here, we identified an obligate function for TAK1 (transforming growth factor β-activated kinase 1, gene name Map3k7) in regulating necroptotic myocyte death, myocardial remodeling, and heart failure propensity. Cardiac-specific ablation of Map3k7 in mice induced spontaneous apoptosis and necroptosis that led to adverse remodeling and heart failure, and these effects were abolished by ablation of tumor necrosis factor receptor-1. Mechanistically, TAK1 functions as a molecular switch in tumor necrosis factor receptor-1 signaling by regulating the formation of 2 cell death complexes, RIP 1 (receptor-interacting protein 1)-FADD (Fas-associated protein with death domain)-caspase 8 and RIP1-RIP3, a process that is dependent on FADD and caspase 8 as scaffolding molecules. Importantly, inhibition of RIP1 or RIP3 largely blocked necroptotic cell death, adverse remodeling, and heart failure in TAK1-deficient mice. Conclusions: These results indicate that TAK1 functions as a key survival factor in the heart by directly antagonizing necroptosis, which is critical for the maintenance of myocardial homeostasis and the prevention of adverse myocardial remodeling.
    Circulation 10/2014; 130(24). DOI:10.1161/CIRCULATIONAHA.114.011195 · 14.43 Impact Factor
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    ABSTRACT: Background Calcium dependent signaling mechanisms play a critical role in platelet activation. Unlike calcium-activated protease and kinase, the contribution of calcium-activated protein serine/threonine phosphatase in platelet activation is poorly understood.Objective To assess the role of catalytic subunit of protein phosphatase 2B (PP2B) or calcineurin in platelet function.ResultsHere, we showed that an increase in PP2B activity was associated with agonist-induced activation of human and murine platelets. Pharmacological inhibitors of the catalytic subunit of protein phosphatase 2B (PP2B-A) such as cyclosporine A (CsA) or tacrolimus (FK506) potentiated aggregation of human platelets. Murine platelets lacking the β isoform of PP2B-A (PP2B-Aβ-/-) displayed increased aggregation with low doses of agonist concentrations. Loss of PP2B-Aβ did not affect agonist-induced integrin αIIbβ3 inside-out signaling, but increased basal Src activation and outside-in αIIbβ3 signaling to p38 mitogen activated protein kinase (MAPK), with a concomitant enhancement in platelet spreading on immobilized fibrinogen and greater fibrin clot retraction. Fibrinogen induced increased p38 activation in PP2B-Aβ-/- platelets were blocked by Src inhibitor. Both PP2B-Aβ-/- platelets and PP2B-Aβ depleted human embryonal kidney 293 αIIbβ3 cells displayed increased adhesion to immobilized fibrinogen. Filamin A, an actin crosslinking phosphoprotein that is known to associate with β3 was dephosphorylated on Ser2152 in fibrinogen adhered wild type but not in PP2B-Aβ-/- platelets. In a FeCl3 injury thrombosis model, PP2B-Aβ-/- mice showed decreased time to occlusion in the carotid artery.Conclusion These observations suggest that PP2B-Aβ by suppressing outside-in αIIbβ3 integrin signaling limits platelet response to vascular injury.This article is protected by copyright. All rights reserved.
    Journal of Thrombosis and Haemostasis 10/2014; 12(12). DOI:10.1111/jth.12761 · 5.72 Impact Factor
  • Jeffery D Molkentin
    Circulation Research 09/2014; 115(8):e21-3. DOI:10.1161/CIRCRESAHA.114.305011 · 11.02 Impact Factor

Publication Stats

28k Citations
3,252.57 Total Impact Points


  • 2009–2015
    • Howard Hughes Medical Institute
      Ashburn, Virginia, United States
    • Hannover Medical School
      • Department of Cardiology and Angiology
      Hanover, Lower Saxony, Germany
    • Washington University in St. Louis
      • Center for Pharmacogenomics
      Saint Louis, MO, United States
    • Duke University
      Durham, North Carolina, United States
    • University of Maryland, Baltimore
      • Department of Physiology
      Baltimore, Maryland, United States
  • 2001–2015
    • University of Cincinnati
      • • Department of Pediatrics
      • • Department of Molecular and Cellular Physiology
      Cincinnati, Ohio, United States
    • Massachusetts General Hospital
      • Division of Cardiology
      Boston, MA, United States
  • 1998–2014
    • Cincinnati Children's Hospital Medical Center
      • • Division of Molecular Cardiovascular Biology
      • • Department of Pediatrics
      Cincinnati, Ohio, United States
  • 2013
    • Temple University
      Filadelfia, Pennsylvania, United States
  • 2007–2012
    • University of Washington Seattle
      • Department of Physiology and Biophysics
      Seattle, WA, United States
    • University of Oslo
      Kristiania (historical), Oslo, Norway
    • University of Cologne
      Köln, North Rhine-Westphalia, Germany
    • Albany Medical College
      • Center for Immunology and Microbial Disease
      Albany, New York, United States
  • 2011
    • Shanghai Jiao Tong University
      Shanghai, Shanghai Shi, China
  • 1996–2011
    • University of Texas Southwestern Medical Center
      • Department of Molecular Biology
      Dallas, Texas, United States
    • The American Society for Biochemistry and Molecular Biology
      Порт-Артур, Texas, United States
  • 2004–2007
    • Boston University
      • Department of Biology
      Boston, Massachusetts, United States
    • University of Freiburg
      Freiburg, Baden-Württemberg, Germany
  • 2006
    • University of Helsinki
      • Department of Physical Sciences
      Helsinki, Uusimaa, Finland
  • 2002–2006
    • University of Toronto
      • Division of Cardiology
      Toronto, Ontario, Canada
  • 2003–2004
    • Maastricht University
      • Department of Cardiology
      Maestricht, Limburg, Netherlands
  • 2000
    • Harvard University
      Cambridge, Massachusetts, United States
  • 1996–1999
    • University of Texas at Dallas
      • Molecular Biology
      Richardson, Texas, United States
  • 1993–1997
    • Medical College of Wisconsin
      • • Department of Physiology
      • • Department of Biochemistry
      Milwaukee, Wisconsin, United States