New Roles of the Primary Cilium in Autophagy

Figure 1

Primary cilium: structure and function. (a) Longitudinal representation of the primary cilium shows an axoneme center formed by highly stable acetylated microtubules that arise from the basal body parked near the nucleus. The components that are transported to the primary cilium (anterograde transport) rely on intraflagellar transport (IFT) proteins attached to Kinesins motor proteins. Conversely, transport from the primary cilium (retrograde transport) depends on different IFT proteins and dynein motor proteins. (b) Transversal representation of the primary cilium shows a 9 + 0 microtubule array, explaining the nonmotile behavior of the primary cilium. (c) Signaling of the primary cilium. On the left, several receptors present at the primary cilium such as platelet-derived growth factor receptor (PDGFR) for activation of the ERK pathway and Patched-1 (PTCH1) activated by Hh ligand for smoothened (SMO) translocation to the ciliary tip and activation of the transcription factor glioma (GLI). On the right, flow activates mechanosensation pathways by activation of the PC1/PC2 calcium channel and noncanonical activation of the Wnt pathway by increasing the expression of inversin in a calcium dependent mechanism, which participates in the degradation of APC and accumulation of β-catenin.

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