Rab14: Role in Cell Polarity and Junction Formation

Abstract

The establishment of polarity in epithelial cells is dependent on the proper distribution of polarity proteins to the apical or basolateral domain. In addition, these cells are dependent on the necessary trafficking of junctional proteins to cells junctions for cell-cell interactions. Rab GTPases are involved in a number of membrane trafficking pathways in the cell. Here we show Rab14's role in regulating the establishment of polarity and junction formation in epithelial cells. Cyst culture was used to show inactive-Rab14 affects single lumen formation and targeting of gp135, an apically targeted protein, thus showing Rab14 may regulate epithelial polarity. In addition, calcium-switch experiments were used to show that not only do cells expressing inactive Rab14 take longer to lose their cell-to-cell contact, but they also regain their contacts more quickly, indicating Rab14 may be playing a role in junction formation. This was further supported by immunostaining experiments examining the distribution of junctional proteins; increased amounts of these proteins at the junction in inactive-Rab14 at the end-point showed that Rab14 may be involved in endocytosis or recycling of junctional components.