Cardiomyocyte apoptosis and inflammation can both contribute to cardiac injury after transient ischemia, yet our understanding of the intracellular signaling pathways controlling these processes in the heart remains incomplete. Our preliminary data suggest that signaling via the Death Receptor (DR) adaptor protein, Fas-associated death domain protein (FADD), plays a critical role in both these processes in cardiomyocytes. The goals of this proposal are to define the role of FADD signaling in models of ischemia-reperfusion injury (IRI) and infarction, to identify the downstream mechanisms that mediate these effects, and to explore the potential of FADD inhibition as a therapeutic intervention. This proposal is based on three hypotheses: 1) that FADD signaling is an important determinant of the functional and anatomic consequences of IRI and infarction, 2) that distinct intracellular signaling pathways mediate FADD's effects on cardiomyocyte survival and inflammation, and that 3) the unusual ability of a dominant negative FADD to simultaneously promote cardiomyocyte survival and inhibit inflammatory signaling will mediate substantial benefits in IRI that are sustained over time. To test these hypotheses, cardiac expression of wild-type and dominant negative FADD, will be achieved through somatic gene transfer, to define the role of FADD signaling and identify potential downstream mediators in both in vitro and in vivo models of ischemia.
In Specific Aim 1, we will examine the role of FADD signaling in in vitro models of cardiomyocyte apoptosis.
In Specific Aim 2, we will define the interactions of FADD and inflammatory signaling via NF-kappaB.
In Specific Aim 3, we will evaluate the anatomic and functional consequences of FADD signaling in both acute and chronic in vivo rat models of IRI and infarction. Defining the intracellular pathways that control cardiomyocyte survival and inflammation, and learning to manipulate these pathways in the heart may provide novel therapeutic approaches for the management of ischemic heart disease.
