DEVELOPING A TET-OFF MOUSE MODEL TO TEST THE EFFECT OF CHANGING FETAL CTNT EXPRESSION ON CARDIOMYOPATHY SEVERITY

Abstract

The sarcomeric dilated cardiomyopathy caused by the tropomyosin mutation Asp230Asn (D230N) shows a ‘bimodal’ distribution of disease severity. A potential explanation for this change in severity is the shift of cardiac Troponin T from its fetal (cTnT1) to adult (cTnT3) isoform because of its binding and proximity to tropomyosin. To explore this, a mouse model was generated that constitutively expresses cTnT1. To test the role of temporal isoform switching in vivo an inducible Tet-Off fetal mouse was generated. This gives us the ability to see if D230N mouse hearts recover of systolic function in response to changing presence of fetal cTnT. In the Tet-OFF system, doxycycline is used to control the expression of a gene of interest, fetal cTnT. Mice founders of different fetal expression levels, were treated longitudinally to observe their responsiveness to doxycycline. Mice were also treated with doxycycline and then removed from the drug to test the recovery of the cardiac protein. To ensure no confounding levels of endogenous fetal were present expression level testing, levels of endogenous fetal were characterized in non-transgenic mice in early life. This research will allow us to further test the effect of cTnT1 in altering disease severity in sarcomeric dilated cardiomyopathies.