Ziliogenese

Ziliogenese, also known as ciliogenesis, is the process by which cilia are formed on eukaryotic cells. It encompasses initiation, assembly of the ciliary axoneme, elaboration of the ciliary membrane, and maturation of the basal body that anchors the organelle to the cell surface. There are primary (non-motile) cilia, typically one per cell, and motile cilia, which can be numerous and beat to move fluids.

Ciliogenese begins when cells exit the cell cycle and form a mature basal body from the mother centriole. Distal appendages recruit vesicles and membrane to build the ciliary pocket; CP110 is removed to permit axoneme elongation. The axoneme, a microtubule-based core, grows from the basal body and is extended by intraflagellar transport, powered by kinesin-2 in the anterograde direction and dynein-2 in retrograde transport, carrying tubulin and other components. The transition zone acts as a selective barrier between the ciliary membrane and the cytoplasm, regulating protein entry.

The cilium participates in signaling, including Hedgehog and Wnt pathways, and, in motile forms, generates motion for mucus clearance or fluid flow. Ciliogenesis is tightly coordinated with the cell cycle: primary cilia are resorbed before mitosis and reassemble afterward. Defects in ciliogenesis or ciliary function underlie ciliopathies such as polycystic kidney disease, Bardet-Biedl syndrome, Joubert syndrome, and primary ciliary dyskinesia, reflecting the central role of Ziliogenese in development and homeostasis.