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. Author manuscript; available in PMC: 2009 Jun 1.
Published in final edited form as: Dev Cell. 2008 Sep;15(3):344–357. doi: 10.1016/j.devcel.2008.08.012

Figure 3. Autophagy-Dependent Regulation of Shh Signaling.

Figure 3

The morphogen sonic hedgehog (Shh) is involved in several aspects of vertebrate development. The model shown is speculative, and autophagy-independent effects may also explain the phenotypes of ambra1, becn1, and UVRAG targeted mutant mice. (A) In wild-type embryos at e9.5, Shh expression is retained within the notochord (Not). At the same developmental stage, ambra1-deficient embryos show Shh expression diffused in the ventral half of the neural tube (NT) and in the floor plate. (B) In the absence of Ambra1, the interaction between Beclin 1 and Vps34 is impaired and autophagy cannot proceed. In addition to the control of Shh signaling during dorso-ventral (D/V) differentiation of the neural tube, autophagy may be involved in regulating the left-right (L/R) axis. In fact, in wild-type embryos, Shh also signals the establishment of the left-right axis in the node cells (see text). In UVRAG mutant humans and Drosophila, the left-right axis symmetry is disturbed, leading to heterotaxy. This could be a consequence of incorrect Shh distribution within the node.