Abstract 297: Cardiac Transforming-growth-factor β-stimulated Clone 22 Gene Expression By Hypertrophic Stimuli

Objectives: Transforming-growth-factor β-stimulated clone 22 (TSC-22) is a leucine zipper protein expressed in many tissues and possessing various transcription-modulating activities. However, its function in the heart remains largely unknown. The aim of the present study was to characterize the cardiac TSC-22 expression. Methods: Acute pressure overload was accomplished in conscious Sprague-Dawley (SD) rats by intravenous infusion of arginine 8 -vasopressin (AVP, 0.05 μg/kg/min) for 4 hours and subcutaneous infusion of angiotensin II (Ang II, 33 μg/kg/h) with and without Ang II receptor type 1 blocker losartan (400 μg/kg/h) by using osmotic minipumps for 2 weeks. Adenovirus-mediated intramyocardial gene transfer of TSC-22 was performed into left ventricle (LV) of SD rats. Experimental myocardial infarction (MI) was produced by ligation of the left anterior descending coronary artery. Cultured neonatal rat ventricular myocytes (NRVM) were treated with endothelin-1 (ET-1, 100 nM). Results: A significant 1.6-fold increase ( P P P P P P P P Conclusion: These results indicate that TSC-22 expression is rapidly activated in response to pressure overload, MI and in ET-1 treated cultured NRVM. Moreover, adenovirus-mediated overexpression of TSC-22 mRNA was associated with elevated left ventricular BNP mRNA levels.