CCBM: Falk Medical Trust

Aim 1 : DCM is a complex disease characterized by changes in the expression of hundreds, if not thousands, of different genes. Identification of specific patterns of altered gene expression in patients with DCM has not yet been achieved. Achievement of this goal is likely to provide novel insights into disease mechanisms, and to pave the way for new treatment strategies. Aim 1 will use microarrays containing probes for human genes to measure and contrast gene expression in tissue samples obtained from control hearts, and from patients diagnosed with DCM. These data will be used to identify genes, and the pathways in which they participate, which are differentially regulated in end-stage DCM.

Aim 2 : Development and progression of DCM cannot be studied in human patients since it is impossible to obtain serial tissue samples, and early stages are rarely identified. Such studies are possible when using animal models. The goal of Aim 2 is to identify mouse models of DCM relevant to study of the human disease. This species has been selected because, in this species, it is possible to undertake diverse, highly integrative studies of gene expression as well as cell and tissue function. Primary mouse models to be employed are: a) an infarct model; b) a model of autoimmune myocarditis; c) a genetic model of myocardial stunning derived from a mutation of the contractile protein troponin I; and d) a genetic model based on mutation of the contractile protein myosin binding protein C. Aim 2A will use microarrays containing probes for mouse genes to study gene expression in ventricular tissue samples obtained from control and failing mouse hearts. Expressed protein levels for a subset of candidate genes will also be measured. Genes and pathways that are differentially regulated in DCM will be identified. Aim 2B will use information obtained in Aim 2A to custom design microarrays that more fully sample genes composing the regulatory networks identified in Aim 2A.

Aim 3 : Development of mouse models relevant to the study of human DCM will make possible the study of molecular mechanisms triggering transition from normal to failing myocardium. Aim 3 will combine state-of-the-art methods for measuring contractile and pumping ability of the heart in the living organism, contractile properties of isolated muscle tissue, and electrophysiological responses of single cells to fully characterize the phenotype and evolution of mouse cardiomyopathy. These data will be correlated with the detailed gene expression information provided by Aim 2 to clarify relationships between genotype and physiological phenotype in DCM, and will be used to identify key signaling steps that may trigger transition from normal to failing myocardium. Aim 3A will track temporal changes in the ability of the heart to pump (using micro-mimiaturized pressure-volume catheters) that occur during development of the various mouse DCM models, and will contrast these changes with those measured in control mice. Aim 3B will isolate small muscle fibers from the same hearts at the same time points studied in Aim 3A. Muscle fiber function will be assessed by measuring force-length, force-frequency, and force-calcium relations. Muscle responses to specific muscle stimulants will be measured, and excitation-contraction coupling processes will be evaluated. Aim 3C will identify the cellular phenotype of DCM using electrophysiological recording and fluorescent microscopy methods combined with data on cell shortening. These studies will yield detailed information regarding the potential influence of gene-abnormalities on a wide range of response properties of cardiac cells and tissue. Aim 3D will use magnetic resonance imaging techniques to measure mechanical function of failing hearts at each of the time points studied in Aims 3A-C, and to assess changes in heart structure including heart volume, wall thickness, and fiber organization.

[ Return To Project Listing ]