Analysis of cardiac gene expression in response to isoproterenol-induced heart failure (part 1). Mus musculus

Myoglobin knockout mice (myo-/-) adapt to the loss of myoglobin by the activation of a variety of compensatory mechanisms on the structural and functional level. In order to analyze to what extent myo-/- mice would tolerate cardiac stress we used the model of chronic isoproterenol application to induce cardiac hypertrophy in myo-/- mice and wild type (WT) controls. After 14 d of isoproterenol infusion cardiac hypertrophy in WT and myo-/- mice reached a similar level. WT mice developed lung oedema and left ventricular dilatation indicating the development of heart failure. In contrast, myo-/- mice displayed conserved cardiac function and no signs of heart failure. Analysis of the cardiac gene expression profile using 40 k mouse oligonucleotide arrays showed that isoproterenol affected the expression of 180 genes in WT but only 92 genes of myo-/- hearts. Only 40 of these genes were regulated in WT and myo-/- hearts. Whereas in WT hearts a prononced induction of genes of the extracellular matrix occurred suggesting a higher level of remodelling, in myo-/- hearts genes of carbon metabolism and genes linked to inhibition of apoptosis and muscular repair were altered. Interestingly, a subset of genes which was altered in myo-/- mice already under basal conditions was differentially expressed in WT hearts under isoproterenol treatment. In summary, our data show, that the genetic background (WT, myo-/-) has a major impact on cardiac gene expression even in the context of an aggressive hypertrophy model such as chronic isoproterenol stimulation. Keywords: gene expression profiling of isoproterenol induced heart failure in WT and myo-/- mice Overall design: We analysed the cardiac gene expression profiles in a total of 32 hearts subdivided into 4 groups (8 WT vehicle, 8 WT ISO, 8 myo-/- vehicle, 8 myo-/- ISO).