Effects of FOS, JUN, TGF-B, Glucocorticoids on Polarized Membrane Traffic
Annual rept. 30 Sep 1998-29 Sep 1999
CALIFORNIA UNIV SAN FRANCISCO
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In polarized epithelial cells, components of the membrane fusion machinery, the t-SNAREs syntaxin 2, 3, 4 and SNAP-23 are differentially localized at the apical andor basolateral plasma membrane domains. Surprisingly, all of these t-SNAREs redistribute to intracellular locations when MDCK or mammary cells lose their cellular polarity. Apical SNAREs re-localize to the previously characterized vacuolar apical compartment VAC while basolateral SNAREs redistribute to a novel organelle that appears to be the basolateral equivalent of the VAC. Both intracellular plasma membrane compartments are associated with the 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.
- Anatomy and Physiology
- Medicine and Medical Research