237. Gene Expression Profiles in Diabetic Cardiomyopathy Following SERCA2a Gene Transfer

Abstract

Diabetes is associated with impaired cardiac function in both humans and animals. As a consequence of myocardial dysfunction, the expression of several genes within the heart is altered. Our aim is to investigate the changes in gene expression profiles accompanying diabetic cardiomyopathy and to identify molecular and cellular pathways and genes that may contribute to cardiac remodeling as a result of the disease and/or its phenotypic rescue by restoration of the sarcoplasmic reticulum calcium ATPase pump (SERCA2a) through adenoviral gene transfer. Using Otsuka Long-Evans Tokushima Fatty (OLETF) rat model of type II diabetes and the Agilent rat chip, which contains oligonucleotide probe sets for 22,000 rat genes, we performed analyses of gene expression by comparing differential changes in age and sex-matched control versus diabetic hearts and diabetic hearts that received gene transfer of SERCA2a (which we previously showed to induce functional improvement in heart failure). Microarray results of selected genes were verified with quantitative real-time PCR and immunoblotting. After normalization and filtration of the data and using a 2-fold cut- off, we found that diabetes has differentially induced the expression of 743 genes (216 up- and 527 down-regulated) which take part in many cellular processes. Our analysis indicates that diabetic cardiomyopathy appears to be, in general, associated with a downregulation of transcripts. Diabetic cardiomyopathic hearts have reduced levels of SERCA2a. Adenoviral gene transfer targeted to these hearts differentially induced the expression of 76 genes and appears, in general, to reverse the transcriptional profile induced by diabetes. Functional gene ontology classification of these genes indicated that SERCA2a restoration is associated with global changes in the cytoskeleton, in cellular energetics and metabolism, in calcium cycling, and in intracellular signaling and transcription regulation pathways. There are also 17 genes of unknown function that are specifically regulated by SERCA overexpression in diabetic hearts. The biological role of some of these novel genes are currently being pursued in other projects. Altogether this investigation provided valuable insight into the pathophysiology of cardiac remodeling and the role of SERCA2a normalization of multiple pathways in diabetes.