March 1, 2013

There are a handful of major signaling modules in development, and I’m fascinated every time a paper comes out showing a new role for one of these pathways, or how multiple pathways interact.  I admire the resourcefulness of cells in using a limited number of proteins to get an unlimited number of things done.  Today’s image is from a paper showing the role of PCP signaling in primary cilia assembly.

The PCP (polar cell polarity) signaling pathway is important in establishing cell polarity throughout development.  PCP signaling has also been linked to the formation and function of cilia, microtubule-based organelles, and a recent study investigates the mechanism between the two.  Primary cilia are solitary cilia that reside on most vertebrate cells and function in signaling, and Zilber and colleagues found that Fuzzy, a PCP signaling effector protein, is involved in primary cilium formation.  Fuzzy localizes to the basal body of cilia, and is necessary to drive Golgi-derived vesicles to the primary cilium.  Fuzzy regulates the localization of Dishevelled, a core PCP protein, to the basal body, and without Fuzzy, PCP signaling is inhibited (while activating the canonical Wnt pathway).  The images above show migrating mammalian cells at the edge of a wound in control (left) and Fuzzy mutant cells (right).  Wound-healing is controlled by PCP signaling in vertebrates, but the role of Fuzzy was unknown.  In control cells, the Golgi network (green) is polarized in front of the nucleus in most migrating cells.  In Fuzzy mutants, the Golgi network is oriented randomly in most cells (asterisks), and cell migration covered less of the initial wound area than in control cells (direction of migration indicated by white arrow).

Zilber, Y., Babayeva, S., Seo, J., Liu, J., Mootin, S., & Torban, E. (2013). The PCP effector Fuzzy controls cilial assembly and signaling by recruiting Rab8 and Dishevelled to the primary cilium Molecular Biology of the Cell, 24 (5), 555-565 DOI: 10.1091/mbc.E12-06-0437