References of "Pfeifer, Gerd P."
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See detailThe tumour suppressor Ras-association domain family protein 1A (RASSF1A) regulates TNF-alpha signalling in cardiomyocytes.
Mohamed, Tamer M. A.; Zi, Min; Prehar, Sukhpal et al

in Cardiovascular research (2014), 103(1), 47-59

AIMS: Tumour necrosis factor-alpha (TNF-alpha) plays a key role in the regulation of cardiac contractility. Although cardiomyocytes are known to express the TNF-alpha receptors (TNFRs), the mechanism of ... [more ▼]

AIMS: Tumour necrosis factor-alpha (TNF-alpha) plays a key role in the regulation of cardiac contractility. Although cardiomyocytes are known to express the TNF-alpha receptors (TNFRs), the mechanism of TNF-alpha signal transmission is incompletely understood. The aim of this study was to investigate whether the tumour suppressor Ras-association domain family protein 1 isoform A (RASSF1A) modulates TNF-alpha signalling in cardiomyocytes. METHODS AND RESULTS: We used RASSF1A knockout (RASSF1A(-/-)) mice and wild-type (WT) littermates in this study. Acute stimulation with a low dose of TNF-alpha (10 microg/kg iv) increased cardiac contractility and intracellular calcium transients' amplitude in WT mice. In contrast, RASSF1A(-/-) mice showed a blunted contractile response. Mechanistically, RASSF1A was essential in the formation of the TNFR complex (TNFRC), where it functions as an adaptor molecule to facilitate the recruitment of TNFR type 1-associated death domain protein and TNFR-associated factor 2 to form the TNF-alpha receptor complex. In the absence of RASSF1A, signal transmission from the TNF-alpha receptor complex to the downstream effectors, such as cytoplasmic phospholipase A2 and protein kinase A, was attenuated leading to the reduction in the activation of calcium handling molecules, such as L-type Ca(2+) channel and ryanodine receptors. CONCLUSION: Our data indicate an essential role of RASSF1A in regulating TNF-alpha signalling in cardiomyocytes, with RASSF1A being key in the formation of the TNFRC and in signal transmission to the downstream targets. [less ▲]

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See detailTumor suppressor Ras-association domain family 1 isoform A is a novel regulator of cardiac hypertrophy.
Oceandy, Delvac; Pickard, Adam; Prehar, Sukhpal et al

in Circulation (2009), 120(7), 607-16

BACKGROUND: Ras signaling regulates a number of important processes in the heart, including cell growth and hypertrophy. Although it is known that defective Ras signaling is associated with Noonan ... [more ▼]

BACKGROUND: Ras signaling regulates a number of important processes in the heart, including cell growth and hypertrophy. Although it is known that defective Ras signaling is associated with Noonan, Costello, and other syndromes that are characterized by tumor formation and cardiac hypertrophy, little is known about factors that may control it. Here we investigate the role of Ras effector Ras-association domain family 1 isoform A (RASSF1A) in regulating myocardial hypertrophy. METHODS AND RESULTS: A significant downregulation of RASSF1A expression was observed in hypertrophic mouse hearts, as well as in failing human hearts. To further investigate the role of RASSF1A in cardiac (patho)physiology, we used RASSF1A knock-out (RASSF1A(-)(/)(-)) mice and neonatal rat cardiomyocytes with adenoviral overexpression of RASSF1A. Ablation of RASSF1A in mice significantly enhanced the hypertrophic response to transverse aortic constriction (64.2% increase in heart weight/body weight ratio in RASSF1A(-)(/)(-) mice compared with 32.4% in wild type). Consistent with the in vivo data, overexpression of RASSF1A in cardiomyocytes markedly reduced the cellular hypertrophic response to phenylephrine stimulation. Analysis of molecular signaling events in isolated cardiomyocytes indicated that RASSF1A inhibited extracellular regulated kinase 1/2 activation, likely by blocking the binding of Raf1 to active Ras. CONCLUSIONS: Our data establish RASSF1A as a novel inhibitor of cardiac hypertrophy by modulating the extracellular regulated kinase 1/2 pathway. [less ▲]

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