Wattiaux R, Jadot M, Dubois F, Wattiaux-De Coninck S
Laboratoire de Chimie Physiologique, Facultés Universitaires Notre-Dame de la Paix, Namur, Belgium.
Biochem Biophys Res Commun. 1996 Mar 27;220(3):569-74. doi: 10.1006/bbrc.1996.0444.
To study the transfer of phagocytosed components from phagosomes to lysosomes, we have investigated phagocytosis by rat liver of killed Staphylococcus aureus labelled with (125)I tyramine cellobiose. Lysosomes were identified by injecting the animals with Triton WR1339, a non ionic detergent that is endocytosed by the liver and accumulates in lysosomes, causing a marked decrease of their density; that allows these organelles to be well separated from other particles in a density gradient. Bacteria were quickly taken up by the liver; their uptake is followed by a slow degradation as ascertained by the increase of acid-soluble radioactivity in the homogenates with time. Triton WR1339 injection does not affect the uptake and the degradation of the particles. Differential centrifugation of homogenates shows that at any time after injection, most of the radioactivity is recovered in the mitochondrial fractions. Distributions of acid precipitable and acid soluble radioactivities amongst subcellular structures present in mitochondrial fractions were studied by isopycnic centrifugation in sucrose gradients, at increasing times after bacteria injection. Results show that: 1) acid-precipitable radioactivity is quasi-exclusively present in gradient fractions of high density, well separated from the fractions where there are recovered lysosomes; 2) with time, acid-soluble radioactivity is more and more associated with lysosomes, however, a significant proportion can be detected for many hours after injection, in gradient fractions where acid-precipitable radioactivity is located. The most plausible explanation of our observations is that phagocytosed particles are degraded in phagosomes and that the degradation products are delivered to lysosomes, probably by a vesicular process.
为了研究吞噬体中吞噬成分向溶酶体的转移，我们利用用（125）I 纤维二糖酪胺标记的死金黄色葡萄球菌，对大鼠肝脏的吞噬作用进行了研究。通过给动物注射 Triton WR1339（一种非离子去污剂，可被肝脏内吞并积聚在溶酶体中，导致其密度显著降低）来识别溶酶体；这使得这些细胞器能够在密度梯度中与其他颗粒很好地分离。细菌很快被肝脏摄取；随着时间的推移，匀浆中酸溶性放射性增加，这表明摄取后细菌会缓慢降解。注射 Triton WR1339 并不影响颗粒的摄取和降解。对匀浆进行差速离心表明，注射后任何时间，大部分放射性都在线粒体部分中回收。在注射细菌后的不同时间，通过在蔗糖梯度中进行等密度离心，研究了线粒体部分中存在的亚细胞结构之间酸沉淀性和酸溶性放射性的分布。结果表明：1）酸沉淀性放射性几乎只存在于高密度的梯度部分中，与回收溶酶体的部分很好地分离；2）随着时间的推移，酸溶性放射性与溶酶体的关联越来越大，然而，在注射后许多小时内，在酸沉淀性放射性所在的梯度部分中仍可检测到相当一部分。对我们观察结果最合理的解释是，吞噬的颗粒在吞噬体中降解，降解产物可能通过囊泡过程传递到溶酶体中。
