Fig. 2.

Proteins involved in the SUMOylation pathway associate with cilia. (A) Transfection of MDCK cells with GFP–SUMO (GFP:SUMO3), shows accumulation of SUMO3 at the base of cilia, marked by acetylated α-tubulin. (B) Immunostaining for the basal body protein, γ-tubulin corroborates the enrichment at the base of the cilium. (C) Ectopic expression of GFP–SUMO3 in OSNs reveals enrichment in dendritic knobs and cell bodies in fixed coronal sections of olfactory epithelium. (D) En face images of OSN knobs transduced with GFP–SUMO3 and Arl13b–mCherry (Arl13b:mCherry). The GFP signal is strongest in the knob, but can be seen in the cilia. Inset shows an image from a 1-µm-thick section, in which it is evident that the GFP–SUMO3 signal is strongest as a ring around the knob, at the base of the projecting cilia. (E) When expressed in OSNs by adenovirus transduction, HA–SUMO3 (HA:SUMO3) is enriched in the nucleus and dendritic knobs, with the HA signal not apparent in the cilia layer. (F) Non-cleavable HA–SUMO3-Q89P (HA:SUMO3Q89P), however localizes to olfactory cilia. OSNs were co-transduced with GFP adenovirus to label transduced neurons as a control. Scale bars: 10 μm.