Overexpression of Bone Morphogenetic Protein 10 in Myocardium Disrupts Cardiac Postnatal Hypertrophic Growth
Hanying Chen^‡1, Weidong Yong^‡1, Shuxun Ren^§, Weihua Shen^‡, Yongzheng He^‡, Karen A. Cox^¶, Wuqiang Zhu^‡, Wei Li^‡, Mark Soonpaa^‡, R. Mark Payne^‡, Diego Franco^||, Loren J. Field^‡, Vicki Rosen^¶, Yibin Wang^§, and Weinian Shou^‡2
‡Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Division of Pediatric Cardiology, Indiana University School of Medicine, Indianapolis, Indiana 46202, the ^§Departments of Anesthesiology, Physiology, and Medicine, Molecular Biology Institute, University of California, Los Angeles, California 90095, the ^¶Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Massachusetts 02115, and the ^||Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain
J. Biol. Chem., Vol. 281, Issue 37, 27481-27491, September 15, 2006

• > Postnatal cardiac hypertrophies have traditionally been classified into physiological or pathological hypertrophies. Both of them are induced by hemodynamic load. Cardiac postnatal hypertrophic growth is regarded as a part of the cardiac maturation process that is independent of the cardiac working load. However, the functional significance of this biological event has not been determined, mainly because of the difficulty in creating an experimental condition for testing the growth potential of functioning heart in the absence of hemodynamic load. Recently, we generated a novel transgenic mouse model (MHC-BMP10) in which the cardiac-specific growth factor bone morphogenetic protein 10 (BMP10) is overexpressed in postnatal myocardium. These MHC-BMP10 mice appear to have normal cardiogenesis throughout embryogenesis, but develop to smaller hearts within 6 weeks after birth. MHC-BMP10 hearts are about half the normal size with 100% penetrance. Detailed morphometric analysis of cardiomyocytes clearly indicated that the compromised cardiac growth in MHC-BMP10 mice was solely because of defect in cardiomyocyte postnatal hypertrophic growth. Physiological analysis further demonstrated that the responses of these hearts to both physiological (e.g. exercise-induced hypertrophy) and pathological hypertrophic stimuli remain normal. In addition, the MHC-BMP10 mice develop subaortic narrowing and concentric myocardial thickening without obstruction by four weeks of age. Systematic analysis of potential intracellular pathways further suggested a novel genetic pathway regulating this previously undefined cardiac postnatal hypertrophic growth event. This is the first demonstration that cardiac postnatal hypertrophic growth can be specifically modified genetically and dissected out from physiological and pathological hypertrophies.
  
  NOTE: Transthoracic echocardiograms were performed using a high resolution Vevo 660 and 770 Imaging System (VisualSonics Inc, Toronto) equipped with a 35 MHz scan probe.