Shh signal and its functional roles in normal and diseased brain

The identification of a Sonic Hedgehog (Shh) signaling pathway in the adult vertebrate central nervous system has paved the way to the characterization of the functional roles of Shh signals in normal and diseased brain. This morphogen is proposed to play a key role in the establishment and maintenance of adult neurogenic niches and to modulate the proliferation of neuronal or glial precursors. Consistent with its role during embryogenesis, alteration of Shh signaling is associated with tumorigenesis while its recruitment in damaged neural tissue might be part of the regenerating process. We will discuss the most recent data of the Hedgehog pathway in the adult brain and its relevance as a novel therapeutic approach for brain diseases including brain tumors.