Intrafibrillar and perinuclear mitochondrial heterogeneity in adult cardiac myocytes

We hypothesized that thromboxane A2 (TxA2) receptor stimulation directly induces apoptosis in adult cardiac myocytes. To investigate this, we exposed cultured adult rat ventricular myocytes (ARVM) to a TxA2 mimetic [1S-[1α,2α(Z),3β(1E,3S*),4α]]-7-[3-[3-hydroxy-4-(4-iodophenoxy)-1-butenyl]-7-oxabicyclo[2.2.1]hept-2-yl]-5-heptenoic acid (I-BOP) for 24 h. Stimulation with I-BOP induced apoptosis in a dose-dependent manner and was completely prevented by a TxA2 receptor antagonist, SQ-29548. We further investigated the role of protein kinase C (PKC) in this process. TxA2 stimulation resulted in membrane translocation of PKC-ζ but not PKC-α, -βII, -δ, and -ε at 3 min and 1 h. The activation of PKC-ζ by I-BOP was confirmed using an immune complex kinase assay. Treatment of ARVM with a cell-permeable PKC-ζ pseudosubstrate peptide (ζ-PS) significantly attenuated apoptosis by I-BOP. In addition, I-BOP treatment decreased baseline Akt activity and its decrease was reversed by treatment with ζ-PS. The inhibition of phosphatidylinositol 3-kinase upstream of Akt by wortmannin or LY-294002 abolished the antiapoptotic effect of ζ-PS. Therefore, our results suggest that the activation of PKC-ζ modulates TxA2 receptor-mediated apoptosis at least, in part, through Akt activity in adult cardiac myocytes.

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Morphometric analysis of the contractile apparatus in cultured adult cardiac myocytes

Journal of Molecular and Cellular Cardiology ◽

10.1016/0022-2828(89)91614-3 ◽

1989 ◽

Vol 21 ◽

pp. S38 ◽

Cited By ~ 2

Author(s):

M DECKER

Keyword(s):

Cardiac Myocytes ◽

Morphometric Analysis ◽

Contractile Apparatus ◽

Adult Cardiac Myocytes

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Myofilament Protein Phosphorylation by PKC in Genetically Engineered Adult Cardiac Myocytes

Cardiac Cell and Gene Transfer ◽

10.1385/1-59259-350-x:159 ◽

2003 ◽

pp. 159-166

Author(s):

Margaret V. Westfall

Keyword(s):

Protein Phosphorylation ◽

Cardiac Myocytes ◽

Genetically Engineered ◽

Adult Cardiac Myocytes

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Abstract 194: Phosphodiesterase 3 Controls Basal cGMP Levels And Regulates cGMP/cAMP Cross-talk In Adult Mouse Ventricular Cardiomyocytes

Circulation Research ◽

10.1161/res.113.suppl_1.a194 ◽

2013 ◽

Vol 113 (suppl_1) ◽

Author(s):

Konrad Götz ◽

Viacheslav Nikolaev

Keyword(s):

Cardiac Myocytes ◽

Cross Talk ◽

Adult Mouse ◽

Temporal Dynamics ◽

Cardiac Contractility ◽

Resonance Energy ◽

Direct Stimulation ◽

Specific Expression ◽

Cgmp Production ◽

Adult Cardiac Myocytes

PURPOSE: cGMP is an important second messenger which is involved in the regulation of cardiac contractility and pathological hypertrophy. In cardiomyocytes, signaling by cGMP is organized in microdomains and is considered cardioprotective. Especially in adult cardiac myocytes, measurements of cGMP have been challenging and little is known about the spatio-temporal dynamics of cGMP. Here we developed a transgenic mouse model to visualize cGMP dynamis in adult cardiac myocytes. Methods: We generated transgenic mice with cardiomyocyte-specific expression of a highly sensitive fluorescence resonance energy transfer (FRET)-based cGMP biosensor red cGES-DE5 and performed FRET measurements in freshly isolated adult mouse ventricular myocytes. To analyze cGMP/cAMP crosstalk, FRET experiments were performed in cardiomyocytes isolated from mice transgenically expressing the cAMP sensor Epac1-camps. Results: Basal cytosolic cGMP levels were very low (~10 nM), but could be markedly increased by stimulation with natriuretic peptides (CNP>>ANP). In contrast, direct stimulation of the soluble guanylyl cyclase (sGC) with NO-donors such as SNAP showed no effect. However, constitutive activity of this cyclase contributes to basal cGMP production, since a clear decrease of basal cGMP levels was observed after stimulation with the sGC inhibitor ODQ. This basal cGMP production is regulated by phosphodiesterase (PDE) activity. Unexpectedly, PDE3 is most important in controlling basal cGMP levels, whereas PDE2 and PDE5 are much less active. We could also show that cGMP pools produced by GC-B after CNP stimulation are mainly regulated by PDE3, so that the receptor and this PDE form one functional unit important for the regulation of cGMP/cAMP cross-talk. Conclusion: In summary, we performed the first FRET-based measurements of cGMP in adult cardiomyocytes and we could highlight the key role of PDE3 in the regulation of basal cGMP levels and cGMP/cAMP cross-talk.

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