Date on Master's Thesis/Doctoral Dissertation

12-2003

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Physiology and Biophysics

Committee Chair

Ping, Peipei

Author's Keywords

Protein kinase C; Proteomic; Myocardial; Subproteome; Cardioprotection; Akt; Nitric oxide synthase

Subject

Myocardial Infarction--Prevention

Abstract

Ischemic heart disease is the leading cause of mortality and morbidity in Western societies. Thus, understanding the molecular mechanisms to reduce myocardial ischemia and limit infarction size are of great importance. Ample evidence has shown that protein kinase C epsilon (PKCepsilon) play an essential role in the genesis of cardioprotection. In particular, our laboratory has shown that activation of PKCepsilon in the heart is sufficient to significantly reduce myocardial infarction due to coronary artery occlusion. However, the molecular mechanism responsible for PKCepsilon-induced cardioprotection remain unclear. Recently, functional proteomic analysis have demonstrated that PKCepsilon forms signaling complexes with various of proteins, including structural proteins, signaling molecules, stress-activated proteins, transcription al/translational factors, metabolism-related proteins, and PKC-binding domain containing proteins, and the coordination of these molecules contributes to cardioprotection. Despite this information which obtained from whole heart lysates, little is known regarding the cellular mechanisms that regulate the assembly of these protein complexes and the specific manner in which these molecules interact with each. Therefore, this dissertation is focused on the characterization of PKCepsilon subproteome and signaling modules within, as well as their regulation during cardioprotection. PKCepsilon-Akt-eNOS signaling module is chosen as my research paradigm because the individual molecule PKCepsilon, Akt and eNOS has been implicated in the prevention of cell death. In addition, both eNOS and Akt were found to exist in the PKCepsilon complex in our initial studies, suggesting that functional coupling among these molecules may be a heretofore unrecognized protective signaling mechanism. Our data demonstrate that the cardiac PKCepsilon signaling subproteome is comprised of various sizes of protein complexes, and the formation of these complexes and modules is regulated by the subcellular localization and extracellular stimulus. During cardioprotection, activation of PKCepsilon enhances the PKCepsilon-Akt-eNOS module formation, and thus contributes to the regulation of nitric oxide production and hence the manifestation of the cardioprotective phenotype. In conclusion, the present research successfully characterizes the myocardial PKCepsilon subproteome and PKCepsilon-Akt-eNOS signaling modules, which serves as an important step towards our complete understanding of the signaling mechanisms underlying PKCepsilon-mediated card ioprotection and ultimately aids in the development of pharmacological agents to protect the heart.

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