Establishing cell polarity by the Lgl family proteins

The lethal giant larvae (lgl) gene was first identified more than 30 years ago in Drosophila and characterized as a tumor suppressor gene. Studies in budding yeast, flies and mammals all indicate that the evolutionarily conserved Lgl family proteins play an important role in cell polarity. Sro7/77, the yeast Lgl homologues, are important for the establishment and reinforcement of cell polarity through their localized interaction and kinetic activation of the post-Golgi secretion machinery. As for higher eukaryotes, both in epithelial polarity and asymmetric cell division, the role of Lgl protein is deployed by localizing proteins to the membrane in a polarized fashion. In addition, Lgl is transiently required during the establishment phase of polarity, implicating that Lgl functions at strategic time points for proliferation control. Studies in cancer biology provide direct connections between malfunction of Lgl and formation, progression and metastasis of various cancers. Here, we review recent advances in the field, focusing on the function of the Lgl family in cellular polarization.