Myosin-X functions in polarized epithelial cells

Prior research has shown that Myosin-X (Myo10) plays a role in filopodia formation in nonpolarized cells. However, its function in polarized epithelial cells remained unclear. Established knowledge includes the role of E-cadherin and ZO-1 in junction assembly. This gap motivated investigations into Myo10's function in epithelial polarity. No prior work had resolved how Myo10 contributes to junction maturation or barrier function. That uncertainty drove the use of polarized epithelial models like MDCK cells. Researchers propose that Myo10 may influence junctional recruitment and paracellular permeability. This gap motivated the calcium-switch experiments to track Myo10 localization. That uncertainty drove the use of GFP tagging to visualize its distribution.

This study aimed to determine how Myo10 functions in polarized epithelial cells. The specific problem addressed was whether Myo10 contributes to junction formation and epithelial morphogenesis. The motivation came from observing Myo10 expression in epithelial-rich tissues like the kidney. The researchers propose that Myo10 may regulate junctional recruitment of E-cadherin and ZO-1. This gap motivated the use of MDCK II cells as a model system. That uncertainty drove calcium-switch experiments to track Myo10 localization. The researchers propose that Myo10 may influence tight junction barrier formation. This gap motivated the use of TER measurements to assess barrier maturation.

The study used Madin-Darby canine kidney II cells as a model system. Calcium-switch experiments were conducted to induce junction assembly. Green fluorescent protein was fused to Myo10 for localization tracking. Total internal reflection fluorescence microscopy was used to image basal filopodia-like structures. Knockdown of Myo10 was achieved using RNA interference techniques. Transepithelial electrical resistance was measured to assess barrier function. Paracellular permeability was tested using fluorescent dextrans. Three-dimensional culture models were used to examine lumen formation defects.

Calcium-switch experiments showed Myo10 localizes to lateral membrane junctions and basal filopodia. Myo10 knockdown delayed recruitment of E-cadherin and ZO-1 to junctions. Peak transepithelial electrical resistance was delayed in Myo10 knockdown cells. Despite eventual TER maturation, Myo10 knockdown cells showed increased paracellular permeability. Myo10 knockdown caused mitotic spindle misorientation in polarized cells. Three-dimensional cysts with Myo10 knockdown had lumen formation defects. These findings suggest Myo10 contributes to junction formation and epithelial morphogenesis. The strongest evidence comes from delayed junctional protein recruitment and altered permeability.

The authors propose that Myo10 functions in junction formation and epithelial morphogenesis. They suggest that Myo10 contributes to the recruitment of E-cadherin and ZO-1 during junction assembly. Myo10 knockdown delayed tight junction barrier maturation, as shown by TER measurements. The authors propose that Myo10 may regulate paracellular permeability in polarized cells. Myo10 knockdown led to mitotic spindle misorientation in epithelial cells. Three-dimensional cysts with Myo10 knockdown had lumen formation defects. These findings suggest Myo10 is involved in epithelial morphogenesis. The authors suggest that Myo10 may coordinate junctional recruitment and barrier regulation.