Mchr1 and Sstr3 colocalize in a subset of hippocampal neuronal cilia.

(A–F) Representative image of the CA1 region of the hippocampus from an adult WT mouse colabeled for Mchr1 (green) and Sstr3 (red). Nuclei are stained with DRAQ5 (blue). Labeling for Mchr1 (A) and Sstr3 (B) reveals the presence of Mchr1- and Sstr3-positive cilia in the hippocampus. Merged image (C) shows colocalization of Mchr1 and Sstr3 on a subset of neuronal cilia. Zoomed in image (D–F) reveals a subset of neuronal cilia that are positive for Mchr1 only (arrow) and a subset that are positive for both Mchr1 and Sstr3 (arrowhead). (G–I) Colabeling of day 7 WT hippocampal neurons with antibodies to Mchr1 (green) and Sstr3 (red). Nuclei are stained with DRAQ5 (blue). Merged image (I) shows Mchr1 and Sstr3 colocalization within the same cilium in vitro. (J) Quantification of day 7 WT hippocampal neurons colabeled for Mchr1 and AC3 or Sstr3 and AC3 reveals that Mchr1localizes to 25.73±3.53% (n = 239) of AC3-positive cilia and Sstr3 localizes to 61.46±4.12% (n = 221) of AC3-positive cilia. (K) Graphical representation of the quantification of day 7 WT hippocampal neurons colabeled for Mchr1 and Sstr3 shows Sstr3 colocalizes to 54.43±5.78% (n = 67) of Mchr1-positive cilia. Scale bars represent 10 µm.