Diacylglycerol Kinases in Ventricular Remodeling

二酰基甘油激酶（DGKs）减弱PKC的活性。5种DGK同工酶，α, β, γ， ε和ζ在大鼠大脑中以其独特的模式表达，而在心脏中的表达和作用知之甚少。我们研究了DGK同工酶是否在大鼠心脏中表达，并定位和量化了这些同工酶在心肌梗死（MI）后不同时间点的表达。Northern blot和原位杂交组织化学分析显示，α、ε和ζ同工酶在正常大鼠心脏中均有表达，而α同工酶表达极低。然后，我们使用原位杂交技术详细分析了心肌梗死后3,7和21天DGK同工酶mRNA的时空分布。mi后第3天和第7天，在坏死肌细胞周围和边缘区检测到ζ同工酶的表达增强，坏死区几乎没有表达。mi后第21天，在梗死区肉芽组织中心检测到ζ同工酶的表达，免疫组化表明，ζ同工酶的表达增加是由粒细胞和巨噬细胞引起的。相反，ε同工酶在整个实验过程中都在活左心室中占优势。通过竞争性RT-PCR获得了这些发现的定量支持。与假手术大鼠相比，未治疗心肌梗死大鼠活心肌中ε同工酶mRNA表达下调29%。心肌梗死后用卡托普利治疗21天，这种情况完全正常化，心脏/体重比降低13%。我们首次证明了三种DGK同工酶在心脏中表达，并且每种同工酶可能在心肌梗死后的左室重构中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.