Rab8 GTPase as a regulator of cell shape.

Endogenous Rab8 is found in dynamic cell structures like filopodia, lamellipodia, protrusions, ruffles, and primary cilia. Activation of Rab8 is linked to the formation of these actin containing structures, whereas inhibition of Rab8 affects negatively their appearance. The activity of Rab8 is controlled by specific guanine nucleotide exchange factors and GTPase activating proteins. Rab8 regulates a membrane recycling pathway that is linked to Arf6, EHD1, Myo5, and Rab11. A hypothesis is presented on the role of Rab8 in the formation of new cell surface domains. The review focuses on the function of Rab8 in cell migration, epithelial polarization, neuron differentiation, and ciliogenesis.