PDE4D9及其抑制剂在糖尿病心肌细胞SERCA2a活性及细胞收缩功能的调控机制

糖尿病心肌病（DCM）是糖尿病患者死亡率高的重要原因，恢复肌浆网钙离子ATP酶2a（SERCA2a）表达或活性是治疗DCM的关键。课题组报道了DCM心肌细胞中磷酸二酯酶4D（PDE4D）高表达，减弱钙离子循环和心肌收缩力。前期研究显示PDE4D9为主要升高亚型，但其亚细胞定位、对SERCA2a活性、钙离子循环和心肌收缩力的影响无报道。本课题将在以往工作基础上，体外用不同亚细胞定位蛋白激酶A探针和PDE4D9显性抑制（DN）多肽，以其他亚型DN多肽为对照；体内给予DCM小鼠AAV9-PDE4D9-DN治疗和用PDE4D9-/-小鼠建立DCM模型，采用荧光共振能量转移、定磷法和等温滴定量热等技术，阐明PDE4D9对SERCA2a活性和心功能的影响，分析二者相互作用关系，为进一步揭示DCM病理机制，确定PDE4D9为治疗靶点，创制解除PDE4D9对SERCA2a抑制的新型抗DCM药提供实验依据。

The high mortality of patients with diabetes mellitus is primarily due to diabetic cardiomyopathy (DCM), and rescue the expression or activity of sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) is the key strategy of treating DCM. We previously reported that the expression of PDE4D was significantly increased in DCM myocytes and leading to the impaired calcium recycle and contractility. Our preliminary data showed that PDE4D9 is the most upregulated PDE4D isotype, however, its subcellular location, its influence on SERCA2a activity and the therapeutic effect of specific PDE4D9 inhibitor on DCM is extremely unclear. Based on the previous research, to elucidate the effect of PDE4D9 on SERCA2a activity and heart function in DCM, and explore the interaction between PDE4D9 and SERCA2a, we will apply anchored protein kinase A biosensors and the dominant negative (DN) PDE4D9 inhibitory peptide, other PDE4D isoform-DN peptide was used as controls in vitro, treat wide type DCM mouse with AAV9-PDE4D9-DN in vivo, and induce DCM model in PDE4D9-/- mouse. Multiple advanced research techniques including fluorescence resonance energy transfer, phosphorus quantitative method and isothermal titration calorimetry will be used. The data will shed light on the pathological mechanism of DCM, conform that PDE4D9 is a promising therapeutic target for DCM, and more importantly, offer experimental proofs for developing novel DCM therapeutic drugs that relieving the suppression of SERCA2a activity by PDE4D9.