Planar cell polarity (PCP) signalling is implicated in the migration of facial branchiomotor (FBM) neurons during vertebrate brain development but how exactly does it function during this process? Cecilia Moens and colleagues now propose that PCP pathway components and a newly identified protein – Nance-Horan syndrome-like 1b (Nhsl1b) – have essential cell-autonomous functions during neuronal migration in zebrafish (see p. ). The researchers identify nhsl1b as a gene required for FBM neuron migration in a forward genetic screen. Nhsl1b localises to FBM neuron membrane protrusions, they report, and interacts with the PCP component Scribble (Scrib) to control FBM neuron migration. In cell transplantation experiments, they show that FBM neuron migration requires the cell-autonomous functions of Nhsl1b, Scrib and the PCP component Vangl2, in addition to the non-cell-autonomous roles of Scrib and Vangl2, which polarise the epithelial cells in the environment of the migrating neurons. The researchers propose, therefore, that Nhsl1b is a neuronal PCP effector that functions in migrating neurons to execute directed cell movements.
