Nanoarchitecture and Molecular Interactions of Epithelial Cell Junction Proteins Revealed by Super‐Resolution Microscopy

• Published in: The FASEB journal 2021-05, Vol.35 (S1), p.n/a, Article fasebj.2021.35.S1.00117
• Main Authors: Naser, Amna, Guiler, William, Lu, Qun, Chen, Yan‐Hua
• Format: Article
• Language: English
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.2021.35.S1.00117

Epithelial cells are polarized with defined apical tight junctions (TJs), lateral adherens junctions (AJs), and basal integrin‐matrix interactions. However, it is increasingly recognized that their characteristic resident proteins can be found in each other's territories and demonstrate previously unrecognized functions. This study presents the nanoarchitecture and nano‐colocalization of cell junction proteins in culture and in intestinal tissue by Stochastic Optical Reconstruction Microscopy (STORM). STORM allows for resolution of approximately 20 nm in the xy plane and 50 nm in the z plane. The Z‐axial view of non‐cancerous MDCK‐II cell AJ proteins, β‐catenin and p120ctn, showed greatest expression density towards the apical milieu of AJ. This is accompanied by the distinctive displacement of p120ctn being apical to β‐catenin. Towards the basal direction, p120ctn and β‐catenin become increasingly colocalized. Interestingly, this topography is lost in metastatic prostate cancer PC3 cells, in that p120ctn localization becomes basal to β‐catenin. The deletion of TJ protein claudin‐7 is sufficient in altering the polarity of p120ctn to basal β‐catenin localization, like that seen in PC3 cells compared to MDCK‐II. Loss of claudin‐7 also significantly altered localization and distribution of many cell junction proteins. Therefore, STORM revealed the regional nanoarchitecture of cellular junctions that were previously unavailable, providing new insights in their potential trans‐compartmental modulation of protein functions.