Cell–cell contacts: ​Tight junctions visualized via ZO-1

High magnification timelapse

Low magnification timelapse

Figure. Timelapse movies of ZO-1 in tight junctions. Timelapse movies of live hiPS cells expressing mEGFP-tagged tight junction protein ZO-1 imaged on a spinning-disk confocal microscope. Images were collected in 3D every 3 min for 1.5 hrs (left) or for 15 hrs (right). Images are maximum intensity projections; playback speed is 910x (left) and 1800x (right) real time.

Observations

• ZO-1 is a tight junction-associated protein that connects adjacent epithelial cells near the apical surface. The tight junctions form a continuous ring around the cell, limiting passage of molecules between the top and bottom of the cells or the tissues they comprise.
• In hiPS cells, ZO-1 forms a ring around each cell near the apical surface. Due to this localization, it is a good marker for the apical cell periphery as the cells grow, divide and move around within the colony.
• The ZO-1 band becomes less coherent and widens during cell division, perhaps due to a release of tension between cells.
• During division, ZO-1 forms rosette-like structures as neighboring cells maintain tight contact with each other when another cell is expelled from the epithelial ‘sheet’. This rosette is resolved as cells move within the colony, grow and divide.