Canivet B, Gorden P, Carpentier J L, Orci L, Freychet P
Mol Cell Endocrinol. 1981 Sep;23(3):311-20. doi: 10.1016/0303-7207(81)90128-3.
It has recently been shown that, when [125I]glucagon is incubated with isolated rat hepatocytes at 37 degrees, the radiolabeled material is progressively internalized by the cell and is found to associate preferentially with lysosome-like structures. To assess the role of this process in the degradation of the hormone, the degradation of [125I]glucagon by isolated rat hepatocytes was examined both in incubation media and in cell extracts, after exposure of the radiolabelled hormone to hepatocytes in the absence and in the presence of lysosomotropic agents NH4Cl (8 mmoles/l) or chloroquine (10 micromoles/l); bacitracin (0.8 mg/ml, i.e. 0.6 mmoles/l) was present in all experimental conditions to minimize extracellular degradation. Neither NH4Cl nor chloroquine altered the time course and steady-state binding of [125I]glucagon, or the degradation of the hormone in incubation media. However, both agents partially inhibited the degradation of cell-associated [125I]glucagon in steady-state conditions. In dissociation experiments, NH4Cl, and even more so chloroquine, decreased the rate and the extent of release of radiolabelled material from the cells. Moreover, after 60 min dissociation, the presence of either agent resulted in less degradation of both cell-associated [125I]glucagon and that released into the medium. These results suggest that lysosomes are involved in the intracellular degradation of glucagon.
最近有研究表明，当将[125I]胰高血糖素与分离的大鼠肝细胞在37摄氏度下孵育时，放射性标记物质会逐渐被细胞内化，并发现其优先与溶酶体样结构结合。为了评估这一过程在激素降解中的作用，在不存在和存在溶酶体促渗剂NH4Cl（8毫摩尔/升）或氯喹（10微摩尔/升）的情况下，将放射性标记的激素与肝细胞接触后，在孵育培养基和细胞提取物中检测了分离的大鼠肝细胞对[125I]胰高血糖素的降解情况；在所有实验条件下均加入杆菌肽（0.8毫克/毫升，即0.6毫摩尔/升）以尽量减少细胞外降解。NH4Cl和氯喹均未改变[125I]胰高血糖素的时间进程和稳态结合，也未改变孵育培养基中激素的降解情况。然而，在稳态条件下，这两种试剂均部分抑制了细胞相关的[125I]胰高血糖素的降解。在解离实验中，NH4Cl，尤其是氯喹，降低了放射性标记物质从细胞中释放的速率和程度。此外，在解离60分钟后，任一试剂的存在都会导致细胞相关的[125I]胰高血糖素和释放到培养基中的胰高血糖素的降解减少。这些结果表明溶酶体参与了胰高血糖素的细胞内降解。
