rottlerin and Cardiomegaly

High circulating androgen in women with polycystic ovary syndrome (PCOS) may increase the risk of cardiovascular disease in offspring. The aim of the present study is to investigate whether maternal androgen excess in the rat PCOS model would lead to cardiac hypertrophy in offspring. Maternal testosterone propionate (maternal-TP)-treated adult female offspring displayed cardiac hypertrophy associated with local high cardiac dihydrotestosterone (DHT). The molecular markers of cardiac hypertrophy along with androgen receptor (AR) and PKCδ, were increased in the Maternal-TP group. Treatment of primary neonatal rat ventricular cardiomyocytes (NRCMs) and H9c2 cells with DHT significantly increased cell size and upregulated PKCδ expression, which could be attenuated by AR antagonist. Treatment with phorbol 12-myristate 13-acetate (PMA), a PKC activator, significantly increased cell size and upregulated myh7 level. Rottlerin, that may inhibit PKCδ, significantly reduced the hypertrophic effect of DHT and PMA on NRCMs and H9c2 cells. Chromatin immunoprecipitation revealed that AR could bind to Pkcδ promoter. Our results indicate that prenatal exposure to testosterone may induce cardiac hypertrophy in adult female rats through enhanced Pkcδ expression in cardiac myocytes.

Topics: Acetophenones; Androgens; Animals; Animals, Newborn; Benzopyrans; Cardiomegaly; Dihydrotestosterone; Female; Gene Expression Regulation; Humans; Myocytes, Cardiac; Polycystic Ovary Syndrome; Pregnancy; Prenatal Exposure Delayed Effects; Protein Kinase C-delta; Rats; Receptors, Androgen; Signal Transduction; Testosterone; Tetradecanoylphorbol Acetate

A cardiac hypertrophy is defined as an increase in heart mass which may either be beneficial (physiological hypertrophy) or detrimental (pathological hypertrophy). This study was undertaken to establish the role of different protein kinase-C (PKC) isoforms in the regulation of cardiac adaptation during two types of cardiac hypertrophy. Phosphorylation of specific PKC-isoforms and expression of their downstream proteins were studied during physiological and pathological hypertrophy in 24 week male Balb/c mice (Mus musculus) models, by reverse transcriptase-PCR, western blot analysis and M-mode echocardiography for cardiac function analysis. PKC-δ was significantly induced during pathological hypertrophy while PKC-α was exclusively activated during physiological hypertrophy in our study. PKC-δ activation during pathological hypertrophy resulted in cardiomyocyte apoptosis leading to compromised cardiac function and on the other hand, activation of PKC-α during physiological hypertrophy promoted cardiomyocyte growth but down regulated cellular apoptotic load resulting in improved cardiac function. Reversal in PKC-isoform with induced activation of PKC-δ and simultaneous inhibition of phospho-PKC-α resulted in an efficient myocardium to deteriorate considerably resulting in compromised cardiac function during physiological hypertrophy via augmentation of apoptotic and fibrotic load. This is the first report where PKC-α and -δ have been shown to play crucial role in cardiac adaptation during physiological and pathological hypertrophy respectively thereby rendering compromised cardiac function to an otherwise efficient heart by conditional reversal of their activation.

Topics: Acetophenones; Adaptation, Physiological; Animals; Apoptosis; Benzopyrans; Cardiomegaly; Cells, Cultured; Collagen; Disease Models, Animal; Down-Regulation; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; Gene Expression Regulation; Heart; Male; Mice; Mice, Inbred BALB C; Muscle Cells; Myocardium; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Physical Conditioning, Animal; Protein Isoforms; Protein Kinase C-alpha; Protein Kinase C-delta; Proto-Oncogene Proteins c-akt; RNA Interference; RNA, Small Interfering; STAT3 Transcription Factor

1. Cardiomyocyte apoptosis plays an important role in the transition from cardiac hypertrophy to heart failure. Hyper-trophic cardiomyocytes show an increased susceptibility to apoptotic stimuli, but the mechanisms remain unclear. 2. We hypothesized that activated protein kinase Cδ (PKCδ) associated with cardiomyocyte hypertrophy could move from the cytoplasm to mitochondria, and subsequently trigger the apoptotic signalling pathway. 3. Hypertrophy was induced in cultured neonatal rat cardiomyocytes using endothelin-1 (ET-1), insulin-like growth factor-1 (IGF-1), thyroid hormone (T(3) ) or angiotensin-II (AngII). AngII at high concentrations (1 and 10 nmol/L) also induced apoptosis. Hypertrophic cells were then treated with AngII with or without specific inhibitors of the angiotensin receptors AT(1) and AT(2) (losartan and PD123319, respectively), endothelin receptor A (BQ-123) and PKCδ (rottlerin). ET-1 plus AngII had a threefold and significant increase in apoptosis in the hypertrophic cultures compared with AngII alone. In association with the increase in apoptosis, this treatment also promoted mitochondrial translocation of PKCδ, and increased expression of cleaved caspase 9 and activity of caspase 3. All of these increases were modulated by concurrent use of the PKCδ inhibitor, rottlerin. 4. The results suggest that apoptotic signalling in hypertrophic cardiomyocytes is determined by mitochondrial pathways involving PKCδ.

Topics: Acetophenones; Angiotensin II; Animals; Apoptosis; Benzopyrans; Cardiomegaly; Caspase 3; Caspase 9; Cells, Cultured; Endothelin-1; Imidazoles; Insulin-Like Growth Factor I; Mitochondria; Myocytes, Cardiac; Peptides, Cyclic; Protein Kinase C-delta; Protein Transport; Pyridines; Rats; Rats, Sprague-Dawley; Receptor, Angiotensin, Type 1; Receptor, Angiotensin, Type 2; Receptors, Endothelin; Signal Transduction; Triiodothyronine