The Hedgehog Signaling Pathway: Where Did It Come From?

The Hedgehog Signaling Pathway: Where Did It Come From?

Hausmann G, von Mering C, Basler K, 2009.

PLoS Biol 7(6): e1000146. doi:10.1371/journal.pbio.1000146

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Complex body plans require sophisticated cell–cell signaling pathways. How these pathways evolved is often not very well understood. Here, we argue that the Hedgehog (Hh) signaling pathway may have arisen from systems that were originally designed for the transport and homeostasis of certain bacterial sterol analogs—the hopanoids. We propose a possible scenario for the evolution of Hh signaling and discuss how evolutionary considerations can shed light on the mysterious communication between the membrane-bound Hh transducers Patched (Ptc) and Smoothened (Smo).