A Chinese hamster ovary cell line with a temperature-conditional defect in receptor recycling is pleiotropically...

We have previously described the isolation of a Chinese hamster ovary cell line, TfT1.11, that has a pleiotropic, temperature-conditional defect in receptor recycling (Cain, C. C., Wilson, R. B., and Murphy, R. F. (1991) J. Biol. Chem. 266, 11746-11752). These cells show a rapid loss of cell surface receptors upon temperature shift due to a reduction in the rate of receptor recycling. We show here that, in addition to altered receptor recycling, TfT1.11 cells show three defects in lysosome biogenesis. At the nonpermissive temperature, they 1) redistribute at least one lysosomal enzyme from lysosomes to endosomes, 2) fail to transfer fluid-phase material from early endosomes to later compartments, and 3) fail to accumulate fluid-phase markers due to increased efflux of internalized material. The results suggest that the processes of recycling from the endosome and movement of material from endosomes to lysosomes are tightly linked.