Pathophysiological role of pyrroline-5-carboxylate synthase (P5CS) in cutis laxa with progeroid features

衰老会导致受损细胞的积累和细胞的丢失，从而导致组织功能的进行性下降。通过对细胞凋亡的调控，线粒体作为氧化应激的来源，在这一过程中起着重要的作用。由吡咯烷-5-羧酸还原酶1(PYCR1)和吡咯烷-5-羧酸合成酶(P5CS)突变引起的节段性类孕症，如皮肤松弛，概括了人类按时间顺序衰老的各个方面。这两个基因都是线粒体脯氨酸循环的一部分，但这一代谢途径的紊乱如何导致这种特有的表型仍然不完全清楚。该项目的目的是进一步研究P5CS酶在生理和病理生理学方面的作用。我们最近描述了从头突变导致亚线粒体分布和P5CS蛋白复合体的生化行为的细微变化。不同的体外方法将被用来研究这种酶在线粒体中的靶向性。此外，还将使用复合体分析和免疫沉淀来获得关于P5CS蛋白复合体的知识。此外，还将使用代谢组学研究通过脯氨酸循环和相关代谢途径的代谢通量。为了补充这些体外方法，我们将研究具有不同程度P5CS功能障碍的小鼠模型。这将在组织学、超微结构和分子水平上为P5CS相关皮肤松弛的组织变化提供详细的见解。这些模型还将允许在体内验证已发现的脯氨酸循环和相关代谢途径的变化。这将澄清哪些变化是所观察到的皮肤松弛表型的原因。我们的研究将使我们能够更深入地了解P5CS相关皮肤松弛的病理生理情况，并为未来的治疗策略提供基础。这将进一步有助于阐明脯氨酸循环如何影响线粒体功能和正常的衰老过程。

Aging leads to a progressive decline of tissue function due to the accumulation of damaged cells and cell loss. Through apoptosis regulation and as a source of oxidative stress mitochondria are a major player in this process. Segmental progeroid disorders like cutis laxa caused by mutations in pyrroline-5-carboxylate reductase 1 (PYCR1) and pyrroline-5-carboxylate synthase (P5CS) recapitulate aspects of chronological human aging. Both gene products a part of the mitochondrial proline cycle, but how disturbance of this metabolic pathway leads to this characteristic phenotype is still incompletely understood. The aim of the proposed project is to further investigate the role of the P5CS enzyme in a physiological and pathophysiological context. We recently described de novo mutations leading to subtle changes in sub-mitochondrial distribution and the biochemical behavior of the P5CS protein complex. Different in vitro approaches will be used to investigate the targeting of this enzyme to its destination within the mitochondria. Furthermore, Complexome profiling and immunoprecipitation will be used to gain knowledge about the P5CS protein complex. Additionally, the metabolic flux through the proline cycle and connected metabolic pathways will be investigated using metabolomics. To complement these in vitro approaches, we will investigate a mouse model with different degrees of P5CS dysfunction. This will provide detailed insights into the tissue changes of P5CS-related cutis laxa at a histological, ultrastructural, and molecular level. These model will also allow to verify in vivo the identified alterations of the proline cycle and connected metabolic pathways. This will clarify which alterations are the cause of the observed cutis laxa phenotype.Our study will allow for a deeper understanding of the pathophysiological situation in P5CS-related cutis laxa and will provide the basis for future treatment strategies. It will furthermore help to clarify how the proline cycle influences mitochondrial function and the normal aging processes.