Browsing by Author "Drosatos, Konstantinos"
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Item Open Access Genomic Binding Patterns of Forkhead Box Protein O1 Reveal Its Unique Role in Cardiac Hypertrophy(Circulation, 2020-09) Pfleger, Jessica; Coleman, Ryan C; Ibetti, Jessica; Roy, Rajika; Kyriazis, Ioannis D; Gao, Erhe; Drosatos, Konstantinos; Koch, Walter JBackground: Cardiac hypertrophic growth is mediated by robust changes in gene expression and changes that underlie the increase in cardiomyocyte size. The former is regulated by RNA polymerase II (pol II) de novo recruitment or loss; the latter involves incremental increases in the transcriptional elongation activity of pol II that is preassembled at the transcription start site. The differential regulation of these distinct processes by transcription factors remains unknown. Forkhead box protein O1 (FoxO1) is an insulin-sensitive transcription factor that is also regulated by hypertrophic stimuli in the heart. However, the scope of its gene regulation remains unexplored. Methods: To address this, we performed FoxO1 chromatin immunoprecipitation–deep sequencing in mouse hearts after 7 days of isoproterenol injections (3 mg·kg −1 ·mg −1 ), transverse aortic constriction, or vehicle injection/sham surgery. Results: Our data demonstrate increases in FoxO1 chromatin binding during cardiac hypertrophic growth, which positively correlate with extent of hypertrophy. To assess the role of FoxO1 on pol II dynamics and gene expression, the FoxO1 chromatin immunoprecipitation–deep sequencing results were aligned with those of pol II chromatin immunoprecipitation–deep sequencing across the chromosomal coordinates of sham- or transverse aortic constriction–operated mouse hearts. This uncovered that FoxO1 binds to the promoters of 60% of cardiac-expressed genes at baseline and 91% after transverse aortic constriction. FoxO1 binding is increased in genes regulated by pol II de novo recruitment, loss, or pause-release. In vitro, endothelin-1– and, in vivo, pressure overload–induced cardiomyocyte hypertrophic growth is prevented with FoxO1 knockdown or deletion, which was accompanied by reductions in inducible genes, including Comtd1 in vitro and Fstl1 and Uck2 in vivo. Conclusions: Together, our data suggest that FoxO1 may mediate cardiac hypertrophic growth via regulation of pol II de novo recruitment and pause-release; the latter represents the majority (59%) of FoxO1-bound, pol II–regulated genes after pressure overload. These findings demonstrate the breadth of transcriptional regulation by FoxO1 during cardiac hypertrophy, information that is essential for its therapeutic targeting.Item Open Access Loss of dynamic regulation of G protein-coupled receptor kinase 2 by nitric oxide leads to cardiovascular dysfunction with aging.(American journal of physiology. Heart and circulatory physiology, 2020-05) Lieu, Melissa; Traynham, Christopher J; de Lucia, Claudio; Pfleger, Jessica; Piedepalumbo, Michela; Roy, Rajika; Petovic, Jennifer; Landesberg, Gavin; Forrester, Steven J; Hoffman, Matthew; Grisanti, Laurel A; Yuan, Ancai; Gao, Erhe; Drosatos, Konstantinos; Eguchi, Satoru; Scalia, Rosario; Tilley, Douglas G; Koch, Walter JNitric oxide (NO) and S-nitrosothiol (SNO) are considered cardio- and vasoprotective substances. We now understand that one mechanism in which NO/SNOs provide cardiovascular protection is through their direct inhibition of cardiac G protein-coupled receptor (GPCR) kinase 2 (GRK2) activity via S-nitrosylation of GRK2 at cysteine 340 (C340). This maintains GPCR homeostasis, including β-adrenergic receptors, through curbing receptor GRK2-mediated desensitization. Previously, we have developed a knockin mouse (GRK2-C340S) where endogenous GRK2 is resistant to dynamic S-nitrosylation, which led to increased GRK2 desensitizing activity. This unchecked regulation of cardiac GRK2 activity resulted in significantly more myocardial damage after ischemic injury that was resistant to NO-mediated cardioprotection. Although young adult GRK2-C340S mice show no overt phenotype, we now report that as these mice age, they develop significant cardiovascular dysfunction due to the loss of SNO-mediated GRK2 regulation. This pathological phenotype is apparent as early as 12 mo of age and includes reduced cardiac function, increased cardiac perivascular fibrosis, and maladaptive cardiac hypertrophy, which are common maladies found in patients with cardiovascular disease (CVD). There are also vascular reactivity and aortic abnormalities present in these mice. Therefore, our data demonstrate that a chronic and global increase in GRK2 activity is sufficient to cause cardiovascular remodeling and dysfunction, likely due to GRK2's desensitizing effects in several tissues. Because GRK2 levels have been reported to be elevated in elderly CVD patients, GRK2-C340 mice can give insight into the aged-molecular landscape leading to CVD.NEW & NOTEWORTHY Research on G protein-coupled receptor kinase 2 (GRK2) in the setting of cardiovascular aging is largely unknown despite its strong established functions in cardiovascular physiology and pathophysiology. This study uses a mouse model of chronic GRK2 overactivity to further investigate the consequences of long-term GRK2 on cardiac function and structure. We report for the first time that chronic GRK2 overactivity was able to cause cardiac dysfunction and remodeling independent of surgical intervention, highlighting the importance of GRK activity in aged-related heart disease.Item Open Access Myocardial Strain and Cardiac Output are Preferable Measurements for Cardiac Dysfunction and Can Predict Mortality in Septic Mice.(Journal of the American Heart Association, 2019-05) Hoffman, Matthew; Kyriazis, Ioannis D; Lucchese, Anna M; de Lucia, Claudio; Piedepalumbo, Michela; Bauer, Michael; Schulze, P Christian; Bonios, Michael J; Koch, Walter J; Drosatos, KonstantinosBackground Sepsis is the overwhelming host response to infection leading to shock and multiple organ dysfunction. Cardiovascular complications greatly increase sepsis-associated mortality. Although murine models are routinely used for preclinical studies, the benefit of using genetically engineered mice in sepsis is countered by discrepancies between human and mouse sepsis pathophysiology. Therefore, recent guidelines have called for standardization of preclinical methods to document organ dysfunction. We investigated the course of cardiac dysfunction and myocardial load in different mouse models of sepsis to identify the optimal measurements for early systolic and diastolic dysfunction. Methods and Results We performed speckle-tracking echocardiography and assessed blood pressure, plasma inflammatory cytokines, lactate, B-type natriuretic peptide, and survival in mouse models of endotoxemia or polymicrobial infection (cecal ligation and puncture, [ CLP ]) of moderate and high severity. We observed that myocardial strain and cardiac output were consistently impaired early in both sepsis models. Suppression of cardiac output was associated with systolic dysfunction in endotoxemia or combined systolic dysfunction and reduced preload in the CLP model. We found that cardiac output at 2 hours post- CLP is a negative prognostic indicator with high sensitivity and specificity that predicts mortality at 48 hours. Using a known antibiotic (ertapenem) treatment, we confirmed that this approach can document recovery. Conclusions We propose a non-invasive approach for assessment of cardiac function in sepsis and myocardial strain and strain rate as preferable measures for monitoring cardiovascular function in sepsis mouse models. We further show that the magnitude of cardiac output suppression 2 hours post- CLP can be used to predict mortality.Item Open Access Restricting mitochondrial GRK2 post-ischemia confers cardioprotection by reducing myocyte death and maintaining glucose oxidation(Science Signaling, 2018-12-11) Sato, Priscila Y; Chuprun, J Kurt; Grisanti, Laurel A; Woodall, Meryl C; Brown, Brett R; Roy, Rajika; Traynham, Christopher J; Ibetti, Jessica; Lucchese, Anna M; Yuan, Ancai; Drosatos, Konstantinos; Tilley, Doug G; Gao, Erhe; Koch, Walter JPreventing GRK2 from localizing to mitochondria lessens the damage induced by myocardial infarction.