Primary cilia signalling at a glance

The primary cilium is a solitary, microtubule-based organelle present on most vertebrate cells, where it functions as a central hub for sensing and transducing extracellular signals. This Cell Science at a Glance article highlights how primary cilia integrate key signalling pathways - including Hedgehog, G protein-coupled receptor, TRP ion channel, receptor tyrosine kinase and transforming growth factor β superfamily signalling - to regulate cellular processes, tissue architecture and organ function. We also describe how defects in ciliary structure or signalling give rise to ciliopathies, a diverse group of disorders affecting multiple organs and systems. Finally, we explore emerging insights into how dynamic changes in ciliary composition generate cell type- and context-specific signalling signatures, positioning the cilium as a convergence point for multiple signalling branches that coordinate development and homeostasis in time and space. The accompanying poster provides further detail on signalling modules and specializations across cell types.