Characterization of caveolae from rat heart: Localization of postreceptor signal transduction molecules and their rearrangement after norepinephrine stimulation

• Published in: Journal of cellular biochemistry Vol. 77; no. 4; pp. 529 - 539
• Main Authors: De Luca, Antonio, Sargiacomo, Massimo, Puca, Annibale, Sgaramella, Giuseppe, De Paolis, Paola, Frati, Giacomo, Morisco, Carmine, Trimarco, Bruno, Volpe, Massimo, Condorelli, Gianluigi
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 15.06.2000
• Subjects: adrenergic; Adrenergic alpha-Agonists - pharmacology; Animals; Blood Pressure - drug effects; caveolae; Caveolin 3; Caveolins; Cell Membrane - drug effects; Cell Membrane - metabolism; Cell Membrane - physiology; Cells, Cultured; Centrifugation, Density Gradient; GTP-Binding Proteins - metabolism; heart; Heart - drug effects; Immunoblotting; Male; Membrane Proteins - metabolism; Myocardium - metabolism; myocytes; Norepinephrine - pharmacology; Rats; Rats, Wistar; Signal Transduction
• ISSN: 0730-2312; 1097-4644
• DOI: 10.1002/(SICI)1097-4644(20000615)77:4<529::AID-JCB2>3.0.CO;2-X

Caveolae are plasma membrane subcompartments that have been implicated in signal transduction. In many cellular systems, caveolae are rich in signal transduction molecules such as G proteins and receptor‐associated tyrosine kinases. An important structural component of the caveolae is caveolin. Recent evidence show that among the caveolin gene family, caveolin‐3 is expressed in skeletal and cardiac muscle and caveolae are present in cardiac myocyte cells. Both the ANP receptor as well as the muscarinic receptor have been localized to the caveolae of cardiac myocytes in culture. These findings prompted us to conduct a further analysis of cardiac caveolae. In order to improve our understanding of the mechanisms of signal transduction regulation in cardiac myocytes, we isolated cardiac caveolae by discontinuous sucrose density gradient centrifugation from rat ventricles and rat neonatal cardiocytes. Our analysis of caveolar content demonstrates that heterotrimeric G proteins, p21ras and receptor‐associated tyrosine kinases are concentrated within these structures. We also show that adrenergic stimulation induces an increase in the amount of diverse α‐ and β‐subunits of G proteins, as well as p21ras, in both in vivo and in vitro experimental settings. Our data show that cardiac caveolae are an important site of signal transduction regulation. This finding suggests a potential role for these structures in physiological and pathological states. J. Cell. Biochem. 77:529–539, 2000. © 2000 Wiley‐Liss, Inc.