Adenovirus-mediated overexpression of cardiac troponin I-interacting kinase promotes cardiomyocyte hypertrophy.

1. Cardiac troponin I-interacting kinase (TNNI3K) is a novel cardiac-specific kinase gene. Quantitative real-time reverse transcription polymerase chain reaction analysis showed a significant increase in TNNI3K mRNA expression in hypertrophic cardiomyocytes induced by endothelin-1 (ET-1). The aim of the present study was to investigate the effects of TNNI3K on neonate rat cardiomyocyte hypertrophy induced by ET-1. 2. Adenoviruses were amplified in 293A cells. To determine a reasonable adenovirus infection dose cardiomyocytes were infected with an adenovirus carrying human TNNI3K (Ad-TNNI3K) at varying multiplicity of infection (MOI) and the expression of TNNI3K was analysed by western blot. 3. Cardiomyocytes were infected with either a control adenovirus carrying green fluorescent protein (Ad-GFP) or Ad-TNNI3K. Compared with Ad-GFP, the Ad-TNNI3K induced an increase in sarcomere organization, cell surface area, (3) H-leucine incorporation and ß-MHC re-expression. This type of hypertrophic phenomenon is similar to that observed in Ad-GFP-infected hypertrophic cardiomyocytes induced by ET-1. To determine the functional role of TNNI3K in ET-1-induced hypertrophic cardiomyocytes, the cells were infected with Ad-GFP or Ad-TNNI3K. Ad-TNNI3K induced an increase in sarcomere organization, cell surface area and (3) H-leucine incorporation compared with Ad-GFP. 4. These results suggest that TNNI3K overexpression induces cardiomyocytes hypertrophy and accelerates hypertrophy in hypertrophic cardiomyocytes. Therefore, TNNI3K might be an interesting target for the clinical treatment of hypertrophy.

[Effects of tongxinluo on mini-swine vascular endothelial integrity and myocardial no-reflow in early reperfusion of acute myocardial infarction].

OBJECTIVE: To assess the effects of tongxinluo on vascular endothelial integrity and myocardial no-reflow in early reperfusion of acute myocardial infarction. METHODS: Forty mini-swines were divided into five groups randomly, sham group, control group, low dose (0.1 g/kg), medium dose (0.2 g/kg) and high dose (0.4 g/kg) groups of Tongxinluo. It was administered at 2 hours pre-reperfusion. Animals except in sham group were subjected to 1.5 hour of coronary occlusion followed by 3 hours of reperfusion. Content of VE-cadherin, beta-catenin, matrix metalloproteinase (MMP)-2 and 9 in myocardium were evaluated; no-reflow area was examined with myocardial contrast echocardiography (MCE) at 1.5 hour of AMI and 3 hours of reperfusion. RESULTS: (1) Compared with that of normal myocardium, content of VE-cadherin and beta-catenin decreased in reperfusion and no-reflow myocardium while MMP-2 and 9 increased significantly (all P < 0.05); (2) Compared with that of control group, a high dose of Tongxinluo could increase significantly the content of VE-cadherin in both reperfusion and no-reflow myocardium, (22.2 +/- 3.2)% vs (32.0 +/- 3.9)% and (14.5 +/- 2.8)% vs (28.3 +/- 2.2)% respectively, beta-catenin, (20.5 +/- 3.5)% vs (27.3 +/- 2.9)% and (13.3 +/- 2.1)% vs (20.6 +/- 2.4)%, while reduce MMP-2, (48.3 +/- 4.1)% vs (29.4 +/- 3.5)% and (57.3 +/- 4.3)% vs (38.2 +/- 4.0)% respectively, MMP-9, (55.6 +/- 4.0)% vs (34.3 +/- 3.5)% and (62.4 +/- 4.8)% vs (44.4 +/- 4.1)%, all P < 0.05; (3) Compared with that of control group, a high dose of Tongxinluo could reduce significantly both no-reflow area, (6.6 +/- 1.7) cm2 vs (4.7 +/- 1.5) cm2, P < 0.05, and percentage (90.8 +/- 3.8)% vs (71.4 +/- 4.1)%, P < 0.05, at 3 hours of reperfusion. CONCLUSION: A high dose of tongxinluo could effectively maintain the integrity of vascular endothelium and attenuate no-reflow area in early reperfusion of acute myocardial infarction.

[Glycolytic and fatty acid metabolic enzyme changes early after acute myocardial ischemia].

OBJECTIVE: To explore the changes of mRNA and protein expressions of glycolytic and fatty acid metabolic enzymes early after acute myocardial ischemia. METHODS: Twelve dogs were randomly divided into 3 groups (sham, 20 min ischemia and 40 min ischemia, n = 4 each). Myocardial samples from ischemic and nonischemic zone were obtained for histology examination, and the mRNA expressions for Phosphofructokinase (PFK), Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), GLUT1, GLUT4, Medium-chain acyl-CoA dehydrogenase (MCAD) and Heart-fatty acid binding protein (H-FABP) were determined by Real Time PCR-SYBR Green RT-PCR. GLUT1 protein expression was determined by immunohistochemistry. The apoptotic cardiomyocytes was evaluated by TUNEL. RESULTS: Compared to sham hearts, H-FABP mRNA was decreased in nonischemic and ischemic zone (P < 0.05) while GLUT1 mRNA expression was significantly increased in nonischemic and ischemic zone (P < 0.05) in dogs underwent 20 and 40 min ischemia. PFK mRNA tended to be higher in ischemic myocardium (P = 0.065) and GAPDH, MCAD as well as GLUT4 remained unchanged post ischemia (all P > 0.05). Positive GLUT1 protein staining was visualized in ischemic myocardium of hearts underwent 20 and 40 min ischemia. The myocardial apoptosis cells was 6.4% +/- 0.9% in sham hearts, 28.0% +/- 3.7% in hearts underwent 20 min ischemia (P < 0.05 vs. sham) and 38.4% +/- 1.9% in hearts underwent 40 min ischemia (P < 0.05 vs. sham). CONCLUSIONS: Significant down and up-regulated glycolytic and fatty acid metabolic enzymes early after myocardial ischemia suggested that these enzymes might play an important role in acute myocardial ischemia.

TNNI3K is a novel mediator of myofilament function and phosphorylates cardiac troponin I.

The phosphorylation of cardiac troponin I (cTnI) plays an important role in the contractile dysfunction associated with heart failure. Human cardiac troponin I-interacting kinase (TNNI3K) is a novel cardiac-specific functional kinase that can bind to cTnI in a yeast two-hybrid screen. The purpose of this study was to investigate whether TNNI3K can phosphorylate cTnI at specific sites and to examine whether the phosphorylation of cTnI caused by TNNI3K can regulate cardiac myofilament contractile function. Co-immunoprecipitation was performed to confirm that TNNI3K could interact with cTnI. Kinase assays further indicated that TNNI3K did not phosphorylate cTnI at Ser23/24 and Ser44, but directly phosphorylated Ser43 and Thr143 in vitro. The results obtained for adult rat cardiomyocytes also indicated that enhanced phosphorylation of cTnI at Ser43 and Thr143 correlated with rTNNI3K (rat TNNI3K) overexpression, and phosphorylation was reduced when rTNNI3K was knocked down. To determine the contractile function modulated by TNNI3K-mediated phosphorylation of cTnI, cardiomyocyte contraction was studied in adult rat ventricular myocytes. The contraction of cardiomyocytes increased with rTNNI3K overexpression and decreased with rTNNI3K knockdown. We conclude that TNNI3K may be a novel mediator of cTnI phosphorylation and contribute to the regulation of cardiac myofilament contraction function.

TNNI3K is a novel mediator of myofilament function and phosphorylates cardiac troponin I

The phosphorylation of cardiac troponin I (cTnI) plays an important role in the contractile dysfunction associated with heart failure. Human cardiac troponin I-interacting kinase (TNNI3K) is a novel cardiac-specific functional kinase that can bind to cTnI in a yeast two-hybrid screen. The purpose of this study was to investigate whether TNNI3K can phosphorylate cTnI at specific sites and to examine whether the phosphorylation of cTnI caused by TNNI3K can regulate cardiac myofilament contractile function. Co-immunoprecipitation was performed to confirm that TNNI3K could interact with cTnI. Kinase assays further indicated that TNNI3K did not phosphorylate cTnI at Ser23/24 and Ser44, but directly phosphorylated Ser43 and Thr143 in vitro. The results obtained for adult rat cardiomyocytes also indicated that enhanced phosphorylation of cTnI at Ser43 and Thr143 correlated with rTNNI3K (rat TNNI3K) overexpression, and phosphorylation was reduced when rTNNI3K was knocked down. To determine the contractile function modulated by TNNI3K-mediated phosphorylation of cTnI, cardiomyocyte contraction was studied in adult rat ventricular myocytes. The contraction of cardiomyocytes increased with rTNNI3K overexpression and decreased with rTNNI3K knockdown. We conclude that TNNI3K may be a novel mediator of cTnI phosphorylation and contribute to the regulation of cardiac myofilament contraction function.