Primary cilium (PC)

The primary cilium is a solitary, non-motile, microtubule-based organelle that projects from the surface of most mammalian cells, acting as a specialized sensory antenna (Satir et al., 2010, PubMed). It serves as a critical hub for various signaling pathways, most notably the Hedgehog (Hh), Wnt, and G protein-coupled receptor (GPCR) pathways, which are essential for embryonic development and adult tissue homeostasis (Goetz & Anderson, 2010, Nature Reviews Genetics). Mutations in genes governing ciliary structure or function lead to a broad class of genetic disorders known as ciliopathies, characterized by polycystic kidneys, retinal degeneration, and skeletal abnormalities (Reiter & Leroux, 2017, Nature Reviews Molecular Cell Biology). In oncology, the primary cilium plays a dual role, either promoting or suppressing tumor growth depending on the oncogenic drivers and the specific signaling context, such as in medulloblastoma or basal cell carcinoma (Higgins et al., 2019, Frontiers in Cell and Developmental Biology). While the organelle itself is not a single molecular target, many therapeutic agents, such as Vismodegib, specifically target proteins like Smoothened that must localize to the cilium to function (FDA, 2012). Emerging research also explores the modulation of ciliary assembly and disassembly as a strategy to control aberrant signaling in various diseases (Anvarian et al., 2019, Nature Reviews Nephrology).

Other names

Non-motile ciliumSensory cilium9+0 cilium

Drugs typically target specific receptors or transducers localized within the primary cilium, such as Smoothened (SMO) in the Hedgehog pathway, or modulate ciliary assembly and disassembly processes to influence downstream signaling cascades (Anvarian et al., 2019, Nature Reviews Nephrology; FDA, 2012).