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Articles by J. i Abe
Total Records ( 2 ) for J. i Abe
  C. L Miller , M Oikawa , Y Cai , A. P Wojtovich , D. J Nagel , X Xu , H Xu , V Florio , S. D Rybalkin , J. A Beavo , Y. F Chen , J. D Li , B. C Blaxall , J. i Abe and C. Yan
 

Rationale: Cyclic nucleotide phosphodiesterases (PDEs) through the degradation of cGMP play critical roles in maintaining cardiomyocyte homeostasis. Ca2+/calmodulin (CaM)-activated cGMP-hydrolyzing PDE1 family may play a pivotal role in balancing intracellular Ca2+/CaM and cGMP signaling; however, its function in cardiomyocytes is unknown.

Objective: Herein, we investigate the role of Ca2+/CaM-stimulated PDE1 in regulating pathological cardiomyocyte hypertrophy in neonatal and adult rat ventricular myocytes and in the heart in vivo.

Methods and Results: Inhibition of PDE1 activity using a PDE1-selective inhibitor, IC86340, or downregulation of PDE1A using siRNA prevented phenylephrine induced pathological myocyte hypertrophy and hypertrophic marker expression in neonatal and adult rat ventricular myocytes. Importantly, administration of the PDE1 inhibitor IC86340 attenuated cardiac hypertrophy induced by chronic isoproterenol infusion in vivo. Both PDE1A and PDE1C mRNA and protein were detected in human hearts; however, PDE1A expression was conserved in rodent hearts. Moreover, PDE1A expression was significantly upregulated in vivo in the heart and myocytes from various pathological hypertrophy animal models and in vitro in isolated neonatal and adult rat ventricular myocytes treated with neurohumoral stimuli such as angiotensin II (Ang II) and isoproterenol. Furthermore, PDE1A plays a critical role in phenylephrine-induced reduction of intracellular cGMP- and cGMP-dependent protein kinase (PKG) activity and thereby cardiomyocyte hypertrophy in vitro.

Conclusions: These results elucidate a novel role for Ca2+/CaM-stimulated PDE1, particularly PDE1A, in regulating pathological cardiomyocyte hypertrophy via a cGMP/PKG-dependent mechanism, thereby demonstrating Ca2+ and cGMP signaling cross-talk during cardiac hypertrophy.

  T. E Kimura , J Jin , M Zi , S Prehar , W Liu , D Oceandy , J. i Abe , L Neyses , A. H Weston , E. J Cartwright and X. Wang
 

Rationale: Mitogen-activated protein kinase (MAPK) pathways provide a critical connection between extrinsic and intrinsic signals to cardiac hypertrophy. Extracellular signal-regulated protein kinase (ERK)5, an atypical MAPK is activated in the heart by pressure overload. However, the role of ERK5 plays in regulating hypertrophic growth and hypertrophy-induced apoptosis is not completely understood.

Objective: Herein, we investigate the in vivo role and signaling mechanism whereby ERK5 regulates cardiac hypertrophy and hypertrophy-induced apoptosis.

Methods and Results: We generated and examined the phenotypes of mice with cardiomyocyte-specific deletion of the erk5 gene (ERK5cko). In response to hypertrophic stress, ERK5cko mice developed less hypertrophic growth and fibrosis than controls. However, increased apoptosis together with upregulated expression levels of p53 and Bad were observed in the mutant hearts. Consistently, we found that silencing ERK5 expression or specific inhibition of its kinase activity using BIX02189 in neonatal rat cardiomyocytes (NRCMs) reduced myocyte enhancer factor (MEF)2 transcriptional activity and blunted hypertrophic responses. Furthermore, the inhibition of MEF2 activity in NRCMs using a non-DNA binding mutant form of MEF2 was found to attenuate the ERK5-regulated hypertrophic response.

Conclusions: These results reveal an important function of ERK5 in cardiac hypertrophic remodeling and cardiomyocyte survival. The role of ERK5 in hypertrophic remodeling is likely to be mediated via the regulation of MEF2 activity.

 
 
 
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