Effects of FOS, JUN, TGF-B, and Glucocorticoids on Polarized Membrane Traffic
Final rept. 30 Sep 1997-29 Sep 2000
CALIFORNIA UNIV SAN FRANCISCO
Pagination or Media Count:
In polarized MDCK kidney epithelial cells, components of the plasma membrane fusion machinery, the t-SNARSs syntaxin 2, 3, 4 and SNAP-23 are differentially localized at the apical andor basolateral plasma membrane domains. Here we identify syntaxin-11 as a novel apical and basolateral plasma membrane t-SNARE. Surprisingly, all of these t-SNARSs redistribute to intracellular locations when MDCK cells lose their cellular polarity. Apical SNARSs re-localize to the previously characterized vacuolar apical compartment VAC while basolateral SNAPEs redistribute to a novel organelle that appears to be the basolateral equivalent of the VAC. Both intracellular plasma membrane compartments have an associated prominent actin cytoskeleton and receive membrane traffic from cognate apical or basolateral pathways, respectively. These findings demonstrate a fundamental shift in plasma membrane traffic towards intracellular compartments while protein sorting is preserved when epithelial cells lose their cell polarity.
- Medicine and Medical Research