Distribution of the surface antigen HAM-4 and cytoskeleton during reformation of bile-canalicular structures in rat primary cultured hepatocytes

The distribution of rat bile-canalicular surface antigen (HAM-4 antigen) and cytoskeletal elements (microtubules, actin filaments, and cytokeratin filaments) was examined during the reformation of bile-canalicular structures (BC-structures) in primary cultures of dissociated hepatocytes obtained following collagenase perfusion. HAM-4 antigen, which initially dispersed after cell dissociation, became focused into regions of cell-to-cell contact even before formation of BC-structures. Typical bile-canalicular microvilli also appeared in these regions before the intercellular spaces were completely closed. Finally, after in vitro reformation of BC, HAM-4 antigen was localized specifically at the BC-surface. The process of BC-reformation and the intracellular organization of actin and cytokeratin filaments were not significantly affected by microtubule inhibitors (nocodazole, colcemid, and colchicine). However, the localization of HAM-4 antigen molecules at the surface of BC was disrupted by these inhibitors, suggesting that the distribution of HAM-4 antigen, which represents a marker for the reconstruction of surface polarity, is dependent on microtubule function.