This is a revised grant application to study PKC alpha in the alcoholic heart. IGF1 is an essential cytokine that is required for normal development of the heart, and it may play a critical physiological role in the normal adult heart as well as influence various pathological conditions. Our laboratory finds that IGF1 activates PKC alpha in adult rat cardiomyocytes, and this results in PKC alpha-dependent activation of MAP kinase, protein synthesis and gene expression. However, in cardiomyocytes from chronic alcohol-exposed rats, there is reduced activation of PKC alpha by IGF1, loss of IGF1-dependent protein synthesis and a significant increase in the unstimulated (basal) state of the IGF1 receptor. Since chronic alcohol exerts such a profound effect on the IGF1 signaling pathway, an examination of how PKC alpha is involved in these changes may uncover novel cellular mechanisms associated with chronic alcohol-induced damage to the heart.
The first aim of this research proposal (1) will be to determine how chronic alcohol alters IGF1-induced PKC alpha activation. What are the changes brought about by chronic alcohol exposure that suppress activation of PKC alpha (e.g. alterations in the IGF1 receptor activation, including the possible involvement of PKC, and the downstream influence on the activities of phospholipase C gamma, PI3 kinase and intracellular tyrosine kinases.
The second aim of this proposal (2) will be to study how alterations in IGF1 signaling affect PKC alpha-dependent regulation of protein synthesis and gene expression. Results from cDNA Expression Arrays indicate that the expression of several essential cardiac-specific genes which are involved in excitation-contraction coupling and cell metabolism (e.g. GIRK4, carnitine palmoyltyl transferase, HSP60, G2/M-specific cyclin G), are regulated by PKC alpha-dependent activation by IGF1. This part of the grant proposal will be done in collaboration with the Daniel Baugh Institute at Thomas Jefferson University, using its BioRobotics MicroGridTAS system for microarray analysis of gene expression. The last aim (3) of the proposal will examine how long term alcohol consumption alters the IGF1 signal transduction pathway using the laboratory's model, the chronic alcohol-fed rat fed a diet containing 37% alcohol for various time points of alcohol exposure (e.g. 2 weeks, 2 months, 4 months, 6 months, 10 months). A comparison of the cardiac Ca2+ channel activity, PKC activation and protein synthesis will be made. The objective is to better define the sequence of events that are associated with alcohol-impaired alterations in IGF1 signaling.
| Ila, Richard; Solem, Michele (2006) Chronic-alcohol exposure alters IGF1 signaling in H9c2 cells via changes in PKC delta. Alcohol 39:169-78 |
| Maniar, Ruchita; Pecherskaya, Anna; Ila, Richard et al. (2005) PKC alpha-dependent regulation of the IGF1 receptor in adult and embryonic rat cardiomyocytes. Mol Cell Biochem 275:15-24 |
