Figure 2

Ciliary signaling. (A) Mechanosensation. Flow induces cilia bending, the polycystin complex is a Ca²⁺ channel and causes an increase of intracellular Ca²⁺ levels that acts as a second messenger. In PKD, the polycystin complex fails to elevate intracellular Ca²⁺ hence mechanosensation is perturbed, leading to inappropriate responses and eventually cyst formation. (B) Schematic representation of Hh-signaling in normal conditions with and without Hh-ligand present. Abnormal Hh-signaling in the absence of primary cilia or in retrograde dynein-2 mutants.