Diacylglycerol Kinases in Ventricular Remodeling

二酰基甘油激酶（Diacylglycerol kinases，DGK）是一种抑制PKC活性的酶，目前已克隆出α、β、γ、ε和β-DGK五种同工酶，它们在大鼠脑中以独特的方式表达，而在心脏中的表达和作用尚不清楚。我们研究了DGK同工酶是否在大鼠心脏中表达，并在心肌梗死（MI）后不同时间点定位和定量这些同工酶的表达。北方印迹分析和原位杂交组织化学显示，正常大鼠心脏有α、ε和ε同工酶的表达，而α同工酶的表达很低。然后，我们详细的时空分布的DGK同工酶的mRNA在MI后3，7和21天使用原位杂交。心肌梗死后3d和7 d，心肌坏死区心肌细胞周围及边缘区表达增强，心肌梗死后21 d，心肌梗死区肉芽组织中心表达增强，免疫组化结果显示，心肌梗死后3d和7 d，心肌坏死区心肌细胞周围及边缘区表达增强，心肌梗死后21 d，心肌梗死区肉芽组织中心表达增强。与此相反，在整个实验过程中，ε同工酶在存活的左心室中的表达占主导地位。竞争性RT-PCR定量支持这些发现。与假手术组相比，未治疗组存活心肌ε同工酶mRNA表达下调29%。这是完全正常的治疗与巯甲丙脯酸21天后，心肌梗死，这是与减少13%的心脏/体重比。我们首次证明了三种DGK同工酶在心脏中表达，并且每种同工酶在MI后的LV重塑中可能发挥不同的功能作用。

Diacylglycerol kinases (DGKs) attenuate the activity of PKC.Five DGK isozymes, α, β, γ, ε and ζ have been cloned and are revealed to be expressed in their unique patterns in the rat brain, whereas little is known about the expression and roles in hearts. We investigated whether DGK isozymes are expressed in rat hearts and localized and quantified the expression of these isozymes at different time points after myocardial infarction (MI). Northern blot analysis and in situ hybridization histochemistry revealed that α, ε and ζ isozymes are expressed in normal rat hearts, while α isozyme expression was very low. We then detailed the spatiotemporal distribution of mRNA for DGK isozymes at 3, 7 and 21 days after MI using in situ hybridization. Enhanced ζ isozyme expression was detected around the necrotic myocytes and at the border zone, with little expression in the necrotic area 3 and 7 days after MI.The ζ isozyme expression was detected in the center of the granulation tissue in the infarct area 21 days after MI.Immunohistochemistry revealed that granulocytes and macrophages were responsible for the increased ζ isozyme expression. In contrast, the expression of ε isozyme was predominant in the viable left ventricle throughout the experiment. Quantitative support by competitive RT-PCR was obtained for these findings. The expression of ε isozyme mRNA is downregulated by 29% in the viable myocardium of untreated MI rats compared with sham-operated rats. This was completely normalized by the treatment with captopril for 21 days after MI, which was associated with a 13% reduction in the heart /body weight ratio. We demonstrated, for the first time, that three DGK isozymes are expressed in the heart and that each isozyme may play different functional roles in LV remodeling after MI.