| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2004: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2003: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
The T-box gene family, which contains a DNA-binding domain of about 200 amino acids (T-box), is a new member of transcription factors. T-box genes thought to be concerned with many developmental processes. We have isolated a Tbx20 gene from chick embryo and found its strong expression in the embryonic heart. In situ hybridization showed that Tbx20 gene expressed in the precardiac mesoderm, and thereafter, in the looped heart, its transcripts were localized in the outflow tract (OT), bulbus cordis, atrioventricular (AV) canal and atrium. Moreover Tbx20 gene expressed strongly in the endocardial cushion tissue of OT and AV regions. Results suggest that Tbx20 gene may play an imporatant role in the cardiogenesis. And Tbx2,-5 and -20 were expressed during atrium development. Developmental anatomy shows that right and left atrium are developed from the sinus venosus, primitive atrium and dorsal mesocardium via the sequential embryonic processes such as, incorporation of the sinus venosus to the atrium, atrial septation and pulmonary venous development. However, mechanisms regulating these processes remain unknown. We examined expression patterns of Tbx2,-5,-20 in the developing atrium from stage 14 to 27 by in situ hybridization. Results suggest that differentially expressed Tbx2,-5,-20 may play an important role in the atrial development, such as septation and pulmonary venous development. Then, to determine whether Tbx20 is necessary for cushion tissue formation, we constructed Tbx20-engrailed2 (dominant negative form to Tbx20) and transfected into AV explants of stage 13 hearts on collagen gel lattice. Results indicated that Tbx20-engrailed2 inhibited endothelial to mesencymal transformation in vitro. These results suggested that Tbx20 may play a important role in cushion tissue formation during chick heart development.
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