| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2003: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2002: ¥1,800,000 (Direct Cost: ¥1,800,000)
|
|---|
| Research Abstract |
1.To examine whether Smad1 activates and plays a role during ischernia-reperfusion of heart in vivo, we generated cardiac-specific Smad1 TG mice by using the α-myosin heavy chain gene promoter. To examine whether Smad1 prevents injury of cardiomyocytes in vivo, we subjected Smad1 TG mice and wild-type mice to ischemia-reperfusion injury induced by 60 minutes of ligation of the left coronary artery and 60 minutes of reperfusion. Histological, TUNEL and DNA ladder analyses showed that Smad1 TG mice presented significantly smaller myocardial infarction and fewer apoptotic deaths of cardiomyocytes than the wild-type mice did. Interestingly, the increased expression of Bcl-xL was more remarkable, whereas caspase 3 was less activated, in the heart of Smad1 TG mice than that in the wild-type mice. These findings suggest that the Smad1 signaling pathway plays a role in cardioprotection against ischemia-reperfusion injury through the induction of Bcl-xL in vivo.
2. Gab1 (Grb2-associated binder-1
… More
), a scaffolding/docking protein, is tyrosine-phosphorylated and associates with protein tyrosine phosphatase SHP2 and p85 phosphatidylinositol 3-kinase upon stimulation with various cytokines and growth factors, including interleukin-6 and leukemia inhibitory factor. We constructed three kinds of adenovirus vectors carrying wild-type Gab1 (AdGab1^<WT>) mutated Gab1 lacking SHP2 binding site (AdGab1^<F627/659>) and β-galactosidase (Adβ-gal). Compared with cardiomyocytes infected with Adb-gal, longitudinal elongation of cardiornyocytes induced by LIE was enhanced in cardiomyocytes infected with AdGab1^<WT> but inhibited in cardiomyocytes infected with AdGab1^<F627/659> Furthermore, activation of extracellular signal-regulated kinase 5 (ERK5) was enhanced in cardiomyocytes infected with AdGab1^<WT> compared with cardiomyocytes infected with Adj3-gal, but repressed in cardiomyocytes infected with AdGab1^<F627/659>. Co-infection of AdGab1^<WT> with adenovirus vector carrying dominant-negative ERK5 abrogated longitudinal elongation of cardiomyocytes induced by LIE. Taken together, these findings indicate that Gabl-SHP2 interaction plays a crucial role in gp13O-dependent longitudinal elongation of cardiomyoctes through activation of ERK5. Less
|
