- The sensory organelle cilium is involved in sensing and transducing important signaling cascades inalmost all cells of our body. These ciliary-mediated pathways affect cellular homeostasis and metabolisms profoundly. However, it is almost completely unknown whether the cellular metabolic state affects the assembly of cilia. This study is to investigate how O-linked -N-acetylglucosamine (O-GlcNAc), a sensor of cellular nutrients, regulates the cilia length. Pharmacologic or genetic inhibition of O-GlcNAcylation led to longer cilia, and vice versa. Further biochemical assays revealed that both -tubulin and HDAC6 (histone deacetylase 6) were O-GlcNAcylated invivo. Invitro enzymatic assays showed that O-GlcNAcylation of either tubulin or HDAC6 promoted microtubule disassembly, which likely in turn caused ciliary shortening. Taken together, these results uncovered a negative regulatory role of O-GlcNAc in modulating the ciliary microtubule assembly. The cross talk between O-GlcNAc and cilium is likely critical for fine-tuning the cellular response to nutrients.