Retroendocytosis of low density lipoprotein. Effect of lysosomal inhibitors on the release of undegraded 125I-low density lipoprotein of altered composition from skin fibroblasts in culture.

摘要: Retroendocytosis of low density lipoprotein (LDL) is a newly identified pathway cellular LDL processing in which that has been internalized via receptors subsequently re-excreted from the cell and not degraded lysosomes. In present study, we examined several characteristics retroendocytosis process as well some physical retroendocytosed LDL. Monkey skin fibroblasts were pulse labeled with 125I-LDL for 4 h at 37 degrees C then washed extensively to remove both surface receptor-bound 125I-LDL. was determined by measuring release trichloroacetic acid-precipitable 125I-material during subsequent 2-h chase period. presence lysosomotropic agents, chloroquine methylamine, absolute amount increased up 3-fold. Without less than 10% cell-associated lost period; this value much 30% agents. processed approximately equivalent degraded. This enhancement seen but observed only when agents Thus, enhanced direct effect but, instead, probably secondary buildup undegraded within cell. As result, under certain conditions, may be quantitatively important alternate absence lysosomal inhibitors, one-third material could have come had removed prior however, surface. The result cytotoxic effects these since [3H]leucine-labeled proteins altered slightly. bulk resulted an active metabolic efflux previously cell.(ABSTRACT TRUNCATED AT 400 WORDS)