Klinik für Anästhesiologie und Intensivmedizin, Universitätsklinikum Essen, Hufelandstr. 55, D-45122 Essen, Germany.
Proc Am Thorac Soc. 2010 Feb;7(1):91-6. doi: 10.1513/pats.200906-035JS.
The ubiquitin-proteasome system is the major intracellular pathway for protein degradation in eukaryotes, and it also generates oligopeptides for antigen presentation. However, the 20S proteasome is also associated with the cell's outer membrane, and observations indicate its physiologic presence and biological activity in the extracellular alveolar space (i.e., in the epithelial lining fluid). Furthermore, its concentration is increased in the adult respiratory distress syndrome, acute lung injury, and other inflammatory lung disease. While its cellular origin, potential extracellular biological role, and mechanisms for extracellular transport are hitherto unclear, extracellular alveolar proteasomes could have a role in protein clearance, digestion of alveolar debris, modification or activation of secreted precursor proteins, and/or antigen processing, both in health and lung disease. This article summarizes available information on the extracellular alveolar proteasome and its possible role in alveolar maintainance, lung injury, and repair.
泛素-蛋白酶体系统是真核细胞中蛋白降解的主要细胞内途径，它还产生用于抗原呈递的寡肽。然而，20S 蛋白酶体也与细胞的外膜相关联，并且观察到其在细胞外肺泡空间（即上皮衬里液）中的生理存在和生物活性。此外，其浓度在成人呼吸窘迫综合征、急性肺损伤和其他炎症性肺病中增加。虽然其细胞起源、潜在的细胞外生物学作用以及细胞外运输的机制尚不清楚，但细胞外肺泡蛋白酶体可能在蛋白质清除、肺泡碎片消化、分泌前体蛋白的修饰或激活以及/或抗原处理中发挥作用，无论是在健康还是在肺部疾病中。本文总结了关于细胞外肺泡蛋白酶体及其在肺泡维持、肺损伤和修复中的可能作用的现有信息。
