Phosphodiesterase 1 signalsomes: the utility of peptide disruptors for pulmonary arterial hypertension

环磷酸腺苷(CAMP)是一种普遍表达的第二信使，它在控制细胞反应中起着关键作用，细胞反应调节着体内广泛的生理过程。CAMP的区域化是cAMP动态时空调控的关键，cAMP动力学决定了cAMP在细胞中的功能。磷酸二酯酶(PDE)是cAMP的水解酶，通过形成特定的蛋白质复合体(信号体)将cAMP限制在亚细胞内，从而支持第二信使的区域化。这种蛋白质复合体还包括cAMP的膜结合蛋白(G蛋白偶联受体)、支架蛋白(A激酶锚定蛋白)和下游介体(蛋白激酶A)。对PDE信号体的鉴定发现了PDE特异的蛋白质复合体，其中许多与心力衰竭、癌症和认知能力下降有关。PDE-蛋白质界面的图谱和新型多肽干扰物的合理设计揭示了这种复合体在细胞功能中的作用。细胞通透性多肽破碎剂对传统小分子具有较高的靶向性，是药物发现的一个令人兴奋的领域。我们发现，PDE家族的一个成员PDE1C在形成肺动脉平滑肌细胞(PASMCs)的cAMP梯度中起着关键作用，其表达和活性的增加是导致肺动脉高压时cAMP降低和PASMC增殖增加的原因(PAH，Murray等，2007)。最近，我们发现PDE1C通过与前列环素(IP)受体相互作用并促进其降解来限制前列环素类似物的疗效，这些类似物目前已被临床批准用于治疗PAH。使用各种分子和生化方法以及“肽芯片”技术(Baillie教授，Blair等人，2019)，该项目旨在定义这个令人兴奋的新发现的PDE1C/IP信号体的相互作用蛋白质、亚细胞定位和功能。此外，我们将利用合成生物学和化学技术开发新型的肽干扰物，包括细胞通透性环肽(Dr Houssen，Iresse等人，2020)，以阐明PDE1C/IP复合体在PASMC中的功能意义及其在PAH中的作用。这个博士项目汇集了阿伯丁大学和格拉斯哥大学在肺部生理学、药理学、生物化学、合成生物学和化学方面的专业知识，将提供最佳的培训环境，并为学生提供一套非常理想的技能。预计这些目标的完成将促进我们对PDE1信号体细胞功能的理解，并发现治疗疾病的新的多肽疗法。

The ubiquitously expressed second messenger, cyclic AMP (cAMP), plays a key role in controlling cellular responses that regulate a wide number of physiological processes throughout the body. Compartmentalization of cAMP is key in the spatio-temporal control of cAMP dynamics that determines its function in cells. Phosphodiesterases (PDEs), which hydrolyse cAMP, underpin compartmentalization of the second messenger by forming specific protein complexes (signalsomes) that restrict cAMP within subcellular compartments. Such protein complexes also include membrane-bound proteins (G protein-coupled receptors), scaffolding proteins (A kinase anchoring proteins) and downstream mediators (protein kinase A) of cAMP. Identification of PDE signalsomes has uncovered PDE-specific protein complexes, many of which are implicated in heart failure, cancer and cognitive decline. Mapping of PDE-protein interfaces and the rational design of novel peptide disrupters has uncovered the role of such complexes in cell function. Cell permeable peptide disrupters, which have higher target specificity to traditional small molecules, represent an exciting area of drug discovery. We have shown a specific PDE family member, PDE1C, plays a pivotal role in shaping cAMP gradients in pulmonary artery smooth muscle cells (PASMCs) and its increased expression and activity accounts for lower cAMP and increased PASMC proliferation in pulmonary arterial hypertension (PAH, Murray et al., 2007). More recently we find PDE1C limits the efficacy of prostacyclin analogues, which are currently clinically approved for PAH, by interacting with the prostacyclin (IP) receptor and enhancing its degradation. Using a variety of molecular and biochemical approaches together with 'peptide chip' technology (Professor Baillie, Blair et al., 2019), this project aims to define the interacting proteins, subcellular localisation and function of this exciting newly discovered PDE1C/IP signalsome. Furthermore, we will develop novel peptide disruptors, including cell permeable cyclic peptides (Dr Houssen, Idress et al., 2020) using synthetic biology and chemistry, to elucidate the functional significance of the PDE1C/IP complex in PASMC and its role in PAH. This PhD project brings together areas of expertise in pulmonary physiology, pharmacology, biochemistry, synthetic biology and chemistry from the University of Aberdeen and University of Glasgow, which will offer an optimal training environment and provide the student with a set of highly desirable skills. It is expected that completion of the aims will advance our understanding of the cellular function of PDE1 signalsomes and uncover novel peptide therapeutics for diseases.