Transcellular transport of low density lipoprotein through cultured newborn rat skin epidermal cell monolayer

Epidermal cells from newborn rat skin were cultured on type IV collagen-coated Millipore filter, and the transport of low density lipoprotein (LDL) labeled with Rhodamine B isothiocyanate (RB-LDL) through the cultured cell layer was examined. The transport of RB-LDL was dependent on temperature and biological energy. The transport was low at 17 degrees C, but above 20 degrees C, it became high with increase in temperature up to 37 degrees C. The transport was markedly inhibited by the energy inhibitors 2-deoxyglucose and NaN3. Furthermore, the transport was saturable at the RB-LDL concentration of about 300 micrograms/ml and the activation energy of the transport was determined as 104.6 kJ/mol. No degradation product of LDL (apoprotein B) was observed during LDL transport through the cultured cell layer. The transport of RB-LDL through skin epidermal cells in culture is suggested to be mediated by transcytotic vesicles, but not by endocytosis and exocytosis via the lysosomal system, nor through cellular junctions.