Heart transplantation in a patient with chloroquine-induced cardiomyopathy.

We present the first report of a patient who underwent heart transplantation (HT) after endomyocardial biopsy (EMB) and revealed chloroquine-induced cardiomyopathy (CIC). This patient, who was treated with chloroquine for 6 years, developed a restrictive cardiomyopathy that progressed to congestive heart failure (CHF) resistant to medical management.

Alterations in protein kinase C isoenzyme expression and autophosphorylation during the progression of pressure overload-induced left ventricular hypertrophy.

Cardiomyocytes express several isoenzymes of protein kinase C (PKC), which as a group have been implicated in the induction of left ventricular hypertrophy (LVH) and its transition to heart failure. Individual PKC isoenzymes also require transphosphorylation and autophosphorylation for enzymatic activity. To determine whether PKC isoenzyme expression and autophosphorylation are altered during LVH progression in vivo, suprarenal abdominal aortic coarctation was performed in Sprague-Dawley rats. Quantitative Western blotting was performed on LV tissue 1, 8 and 24 weeks after aortic banding, using antibodies specific for total PKCalpha, PKCdelta and PKCepsilon, and their C-terminal autophosphorylation sites. Aortic banding produced sustained hypertension and gradually developing LVH that progressed to diastolic heart failure over time. PKCepsilon levels and autophosphorylation were not significantly different from sham-operated controls during any stage of LVH progression. PKCalpha expression levels were also unaffected during the induction of LVH, but increased 3.2 +/- 0.8 fold during the transition to heart failure. In addition, there was a high degree of correlation between PKCalpha levels and the degree of LVH in 24 week banded animals. However, autophosphorylated PKCalpha was not increased at any time point. In contrast, PKCdelta autophosphorylation was increased prior to the development of LVH, and also during the transition to heart failure. The increased PKCdelta autophosphorylation in 1 week banded rats was not accompanied by an increase in total PKCdelta, whereas total PKCdelta levels were markedly increased (6.0 +/- 1.7 fold) in 24 week banded animals. Furthermore, both phosphorylated and total PKCdelta levels were highly correlated with the degree of LVH in 24 week banded rats. In summary, we provide indirect evidence to indicate that PKCdelta may be involved in the induction of pressure overload LVH, whereas both PKCdelta and PKCalpha may be involved in the transition to heart failure.

Isoenzyme-selective regulation of SERCA2 gene expression by protein kinase C in neonatal rat ventricular myocytes.

Patients with cardiac hypertrophy and heart failure display abnormally slowed myocardial relaxation, which is associated with downregulation of sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA2) gene expression. We previously showed that SERCA2 downregulation can be simulated in cultured neonatal rat ventricular myocytes (NRVM) by treatment with the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA). However, NRVM express three different PMA-sensitive PKC isoenzymes (PKCalpha, PKCepsilon, and PKCdelta), which may be differentially regulated and have specific functions in the cardiomyocyte. Therefore, in this study we used adenoviral vectors encoding wild-type (wt) and kinase-defective, dominant negative (dn) mutant forms of PKCalpha, PKCepsilon, and PKCdelta to analyze their individual effects in regulating SERCA2 gene expression in NRVM. Overexpression of wtPKCepsilon and wtPKCdelta, but not wtPKCalpha, was sufficient to downregulate SERCA2 mRNA levels, as assessed by Northern blotting and quantitative, real-time RT-PCR (69 +/- 7 and 61 +/- 9% of control levels for wtPKCepsilon and wtPKCdelta, respectively; P < 0.05 for each adenovirus; n = 8 experiments). Conversely, overexpression of all three dnPKCs appeared to significantly increase SERCA2 mRNA levels (dnPKCdelta > dnPKCepsilon > dnPKCalpha). dnPKCdelta overexpression produced the largest increase (2.8 +/- 1.0-fold; n = 11 experiments). However, PMA treatment was still sufficient to downregulate SERCA2 mRNA levels despite overexpression of each dominant negative mutant. These data indicate that the novel PKC isoenzymes PKCepsilon and PKCdelta selectively regulate SERCA2 gene expression in cardiomyocytes but that neither PKC alone is necessary for this effect if the other novel PKC can be activated.

PYK2 expression and phosphorylation increases in pressure overload-induced left ventricular hypertrophy.

Proline-rich tyrosine kinase 2 (PYK2) is a member of the focal adhesion kinase (FAK) family of nonreceptor protein tyrosine kinases. PYK2 has been implicated in linking G protein-coupled receptors to activation of mitogen-activated protein kinase cascades and cellular growth in a variety of cell types. To determine whether PYK2 expression and phosphorylation is altered in left ventricular (LV) myocardium undergoing LV hypertrophy (LVH) and heart failure in vivo, suprarenal abdominal aortic coarctation was performed in 160-g male Sprague-Dawley rats. Immunohistochemistry and Western blotting were performed on LV tissue 1, 8, and 24 wk after aortic banding. Aortic banding produced sustained hypertension and gradually developing LVH. PYK2 levels were increased 1.8 +/- 0.2-, 2.7 +/- 0.6-, and 2.0 +/- 0.2-fold in 1-, 8-, and 24-wk banded animals compared with their respective sham-operated controls. The increase in PYK2 expression was paralleled by an increase in PYK2 phosphorylation, both of which preceded the development of LVH. Immunohistochemistry revealed that enhanced PYK2 expression occurred predominantly in the cardiomyocyte population. Furthermore, there was a high degree of correlation (R = 0.75; P < 0.001) between the level of PYK2 and the degree of LVH in 24-wk sham and banded animals. In contrast, FAK levels and FAK phosphorylation were not increased before the development of LVH. However, there was a high degree of correlation (R = 0.68; P < 0.001) between the level of FAK and the degree of LVH in 24-wk sham and banded rats. There was also a significant increase in the ratio of phosphospecific anti-FAK to FAK at this time point. These data are consistent with a role for PYK2 in the induction of pressure overload-induced cardiomyocyte hypertrophy, and suggest that PYK2 and FAK have distinctly different roles in LVH progression.