Abstract

Over the years, significant progress has been made in understanding the nature of membrane-associated polarity factors and the molecular mechanisms driving the formation of cortical polarity domains during epithelial cell polarisation. However, how cortical apical-basal polarity translates into intracellular asymmetries remains largely unclear. In particular, the formation of apical-to-basal-oriented non-centrosomal microtubule arrays, which maintain epithelial cell polarity by directing the asymmetric distribution of vesicles and proteins, is not well understood. Based on the Drosophila spectraplakin actin-binding domain, we designed new actin-binding probes that selectively recognised the apical and lateral actin cortices in epithelial cells. Our experiments showed that the actin cortex in polarised epithelial cells is more heterogeneous than previously assumed with different types of actin networks present in the apical and lateral cortical domains. These specialised networks may selectively recruit distinct subsets of actin-binding proteins and play a crucial role in translating the asymmetric distribution of cortical polarity factors into the polarised organisation of microtubules and membrane trafficking.