Sonic Hedgehog (Shh) is a secreted morphogen that is an essential regulator of patterning and growth. The Shh full-length protein undergoes autocleavage in the endoplasmic reticulum to generate the biologically active N-terminal fragment (ShhN), which is destined for secretion. We identified sortilin (Sort1), a member of the VPS10P-domain receptor family, as a new Shh trafficking receptor. We demonstrate that Sort–Shh interact by performing coimmunoprecipitation and proximity ligation assays in transfected cells and that they colocalize at the Golgi. Sort1 overexpression causes re-distribution of ShhN and, to a lesser extent, of full-length Shh to the Golgi and reduces Shh secretion. We show loss of Sort1 can partially rescue Hedgehog-associated patterning defects in a mouse model that is deficient in Shh processing, and we show that Sort1 levels negatively regulate anterograde Shh transport in axons in vitro and Hedgehog-dependent axon–glial interactions in vivo. Taken together, we conclude that Shh and Sort1 can interact at the level of the Golgi and that Sort1 directs Shh away from the pathways that promote its secretion.
The authors declare no competing or financial interests.
C.C., experimental conception, design, data acquisition, analysis, interpretation, manuscript preparation, revision. S.B., experimental conception, design, data acquisition, interpretation, manuscript revision. P.E.B.N., data acquisition, interpretation, manuscript preparation. J.P., experimental conception, design, data acquisition, manuscript revision. C.M., data acquisition, analysis. E.A.B., data interpretation, manuscript preparation. R.R., experimental conception, design, data interpretation. F.A.J., data acquisition, interpretation. C.M., data interpretation, manuscript revision. A.C., data interpretation, manuscript revision. V.A.W., experimental conception, design, data analysis, interpretation, manuscript preparation, revision.
This work was supported by an operating grant [number 97765] from the Canadian Institutes of Health Research to V.A.W.; and a postdoctoral fellowship from Helmholtz-Gemeinschaft to A.C.
Supplementary information available online at http://jcs.biologists.org/lookup/doi/10.1242/jcs.183541.supplemental
- Received November 18, 2015.
- Accepted August 26, 2016.
- © 2016. Published by The Company of Biologists Ltd