Dynamics of epithelial cell polarity in Drosophila: how to regulate the regulators?

Apico-basal polarity is a hallmark of epithelial tissues. The integrated activity of several evolutionarily conserved protein complexes is essential to control epithelial polarity during development and homeostasis. Many components of these protein complexes were originally identified in genetic screens performed in Drosophila or Caenorhabditis elegans due to defects in cell polarity. With time, it became obvious that these protein complexes not only control various aspects of apico-basal polarity, but also perform a plethora of other functions, such as growth control, organization of endocytic activity, regulation of signaling and asymmetric cell division, to mention just a few. Here we summarize some results mostly obtained from studies in Drosophila to elucidate how variation in protein composition and modification of individual components contribute to make polarity complexes versatile platforms to fulfill a variety of functions.