The SARS Coronavirus E Protein Interacts with PALS1 and Alters Tight Junction Formation and Epithelial Morphogenesis

Teoh, Kim-Tat; Siu, Yu-Lam; Chan, Wing-Lim; Schlüter, Marc A.; Liu, Chia-Jen; Peiris, J. S. Malik; Bruzzone, Roberto; Margolis, Benjamin; Nal, Béatrice

We initially verified that the majority (61%) of MDCKII-eGFP-PALS1 cells (540/885) formed single lumen cysts with distinct apicobasal polarity (Figure 5, A and C). As expected, control MDCKII cysts expressing either eGFP or eGFP-PALS1 and HcRed fluorescent protein showed a similar percentage of cysts with single lumens and maintained polarity (data not shown). In both MDCKII-eGFP-PALS1 and MDCKII-eGFP-PALS1, HcRed cells, eGFP-PALS1 was found on apical membranes of the cysts, facing the internal lumen and present at TJ as indicated by its colocalization with the tight junction associated protein ZO-1 (Figure 5A and data not shown). HcRed fluorescent protein was diffusely distributed in the cytoplasm of the latter cells (data not shown). Together, these results strongly suggest that epithelial polarity in the two control cell lines, MDCKII eGFP-PALS1 and MDCKII eGFP-PALS1, HcRed, is maintained.