Integration of cAMP signaling and the ubiquitin system in the control of primary cilium

The primary cilium is an antenna-like sensory organelle able to receive extracellular signals and it is localized on the surface of most human cells. In my thesis, I investigated the connection between G-protein coupled receptor (GPCR) signaling and the ubiquitin proteasome system (UPS) pathway in the control of cilium stability. I identified, at pericentriolar region, a trimeric complex composed by PCM1, NEK10 and PKA. I demonstrated that NEK10 has a crucial role in ciliogenesis. Phosphorylation by PKA primes NEK10 to proteasomal degradation. Disappearance of NEK10 promotes cilia resorption. I identified CHIP as the E3 ubiquitin ligase responsible of NEK10 ubiquitination and I demonstrated that CHIP mediates the effects of cAMP on primary cilium stability. Derangement of this control mechanism was observed in proliferative and genetic disorders. Collectively, the findings unveil a pericentriolar kinase signalosome that efficiently links the cAMP cascade with the ubiquitin-proteasome system, controlling essential aspects of ciliogenesis.